xref: /freebsd/sys/netinet/tcp_stacks/rack.c (revision 0957b409)
1 /*-
2  * Copyright (c) 2016-2018 Netflix, Inc.
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions
6  * are met:
7  * 1. Redistributions of source code must retain the above copyright
8  *    notice, this list of conditions and the following disclaimer.
9  * 2. Redistributions in binary form must reproduce the above copyright
10  *    notice, this list of conditions and the following disclaimer in the
11  *    documentation and/or other materials provided with the distribution.
12  *
13  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
14  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
16  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
17  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
18  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
19  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
20  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
21  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
22  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
23  * SUCH DAMAGE.
24  *
25  */
26 
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
29 
30 #include "opt_inet.h"
31 #include "opt_inet6.h"
32 #include "opt_ipsec.h"
33 #include "opt_tcpdebug.h"
34 
35 #include <sys/param.h>
36 #include <sys/module.h>
37 #include <sys/kernel.h>
38 #ifdef TCP_HHOOK
39 #include <sys/hhook.h>
40 #endif
41 #include <sys/lock.h>
42 #include <sys/malloc.h>
43 #include <sys/lock.h>
44 #include <sys/mutex.h>
45 #include <sys/mbuf.h>
46 #include <sys/proc.h>		/* for proc0 declaration */
47 #include <sys/socket.h>
48 #include <sys/socketvar.h>
49 #include <sys/sysctl.h>
50 #include <sys/systm.h>
51 #ifdef NETFLIX_STATS
52 #include <sys/stats.h>
53 #endif
54 #include <sys/refcount.h>
55 #include <sys/queue.h>
56 #include <sys/smp.h>
57 #include <sys/kthread.h>
58 #include <sys/kern_prefetch.h>
59 
60 #include <vm/uma.h>
61 
62 #include <net/route.h>
63 #include <net/vnet.h>
64 
65 #define TCPSTATES		/* for logging */
66 
67 #include <netinet/in.h>
68 #include <netinet/in_kdtrace.h>
69 #include <netinet/in_pcb.h>
70 #include <netinet/ip.h>
71 #include <netinet/ip_icmp.h>	/* required for icmp_var.h */
72 #include <netinet/icmp_var.h>	/* for ICMP_BANDLIM */
73 #include <netinet/ip_var.h>
74 #include <netinet/ip6.h>
75 #include <netinet6/in6_pcb.h>
76 #include <netinet6/ip6_var.h>
77 #include <netinet/tcp.h>
78 #define	TCPOUTFLAGS
79 #include <netinet/tcp_fsm.h>
80 #include <netinet/tcp_log_buf.h>
81 #include <netinet/tcp_seq.h>
82 #include <netinet/tcp_timer.h>
83 #include <netinet/tcp_var.h>
84 #include <netinet/tcp_hpts.h>
85 #include <netinet/tcpip.h>
86 #include <netinet/cc/cc.h>
87 #ifdef NETFLIX_CWV
88 #include <netinet/tcp_newcwv.h>
89 #endif
90 #include <netinet/tcp_fastopen.h>
91 #ifdef TCPDEBUG
92 #include <netinet/tcp_debug.h>
93 #endif				/* TCPDEBUG */
94 #ifdef TCP_OFFLOAD
95 #include <netinet/tcp_offload.h>
96 #endif
97 #ifdef INET6
98 #include <netinet6/tcp6_var.h>
99 #endif
100 
101 #include <netipsec/ipsec_support.h>
102 
103 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
104 #include <netipsec/ipsec.h>
105 #include <netipsec/ipsec6.h>
106 #endif				/* IPSEC */
107 
108 #include <netinet/udp.h>
109 #include <netinet/udp_var.h>
110 #include <machine/in_cksum.h>
111 
112 #ifdef MAC
113 #include <security/mac/mac_framework.h>
114 #endif
115 #include "sack_filter.h"
116 #include "tcp_rack.h"
117 #include "rack_bbr_common.h"
118 
119 uma_zone_t rack_zone;
120 uma_zone_t rack_pcb_zone;
121 
122 #ifndef TICKS2SBT
123 #define	TICKS2SBT(__t)	(tick_sbt * ((sbintime_t)(__t)))
124 #endif
125 
126 struct sysctl_ctx_list rack_sysctl_ctx;
127 struct sysctl_oid *rack_sysctl_root;
128 
129 #define CUM_ACKED 1
130 #define SACKED 2
131 
132 /*
133  * The RACK module incorporates a number of
134  * TCP ideas that have been put out into the IETF
135  * over the last few years:
136  * - Matt Mathis's Rate Halving which slowly drops
137  *    the congestion window so that the ack clock can
138  *    be maintained during a recovery.
139  * - Yuchung Cheng's RACK TCP (for which its named) that
140  *    will stop us using the number of dup acks and instead
141  *    use time as the gage of when we retransmit.
142  * - Reorder Detection of RFC4737 and the Tail-Loss probe draft
143  *    of Dukkipati et.al.
144  * RACK depends on SACK, so if an endpoint arrives that
145  * cannot do SACK the state machine below will shuttle the
146  * connection back to using the "default" TCP stack that is
147  * in FreeBSD.
148  *
149  * To implement RACK the original TCP stack was first decomposed
150  * into a functional state machine with individual states
151  * for each of the possible TCP connection states. The do_segement
152  * functions role in life is to mandate the connection supports SACK
153  * initially and then assure that the RACK state matches the conenction
154  * state before calling the states do_segment function. Each
155  * state is simplified due to the fact that the original do_segment
156  * has been decomposed and we *know* what state we are in (no
157  * switches on the state) and all tests for SACK are gone. This
158  * greatly simplifies what each state does.
159  *
160  * TCP output is also over-written with a new version since it
161  * must maintain the new rack scoreboard.
162  *
163  */
164 static int32_t rack_precache = 1;
165 static int32_t rack_tlp_thresh = 1;
166 static int32_t rack_reorder_thresh = 2;
167 static int32_t rack_reorder_fade = 60000;	/* 0 - never fade, def 60,000
168 						 * - 60 seconds */
169 static int32_t rack_pkt_delay = 1;
170 static int32_t rack_inc_var = 0;/* For TLP */
171 static int32_t rack_reduce_largest_on_idle = 0;
172 static int32_t rack_min_pace_time = 0;
173 static int32_t rack_min_pace_time_seg_req=6;
174 static int32_t rack_early_recovery = 1;
175 static int32_t rack_early_recovery_max_seg = 6;
176 static int32_t rack_send_a_lot_in_prr = 1;
177 static int32_t rack_min_to = 1;	/* Number of ms minimum timeout */
178 static int32_t rack_tlp_in_recovery = 1;	/* Can we do TLP in recovery? */
179 static int32_t rack_verbose_logging = 0;
180 static int32_t rack_ignore_data_after_close = 1;
181 /*
182  * Currently regular tcp has a rto_min of 30ms
183  * the backoff goes 12 times so that ends up
184  * being a total of 122.850 seconds before a
185  * connection is killed.
186  */
187 static int32_t rack_tlp_min = 10;
188 static int32_t rack_rto_min = 30;	/* 30ms same as main freebsd */
189 static int32_t rack_rto_max = 30000;	/* 30 seconds */
190 static const int32_t rack_free_cache = 2;
191 static int32_t rack_hptsi_segments = 40;
192 static int32_t rack_rate_sample_method = USE_RTT_LOW;
193 static int32_t rack_pace_every_seg = 1;
194 static int32_t rack_delayed_ack_time = 200;	/* 200ms */
195 static int32_t rack_slot_reduction = 4;
196 static int32_t rack_lower_cwnd_at_tlp = 0;
197 static int32_t rack_use_proportional_reduce = 0;
198 static int32_t rack_proportional_rate = 10;
199 static int32_t rack_tlp_max_resend = 2;
200 static int32_t rack_limited_retran = 0;
201 static int32_t rack_always_send_oldest = 0;
202 static int32_t rack_sack_block_limit = 128;
203 static int32_t rack_use_sack_filter = 1;
204 static int32_t rack_tlp_threshold_use = TLP_USE_TWO_ONE;
205 
206 /* Rack specific counters */
207 counter_u64_t rack_badfr;
208 counter_u64_t rack_badfr_bytes;
209 counter_u64_t rack_rtm_prr_retran;
210 counter_u64_t rack_rtm_prr_newdata;
211 counter_u64_t rack_timestamp_mismatch;
212 counter_u64_t rack_reorder_seen;
213 counter_u64_t rack_paced_segments;
214 counter_u64_t rack_unpaced_segments;
215 counter_u64_t rack_saw_enobuf;
216 counter_u64_t rack_saw_enetunreach;
217 
218 /* Tail loss probe counters */
219 counter_u64_t rack_tlp_tot;
220 counter_u64_t rack_tlp_newdata;
221 counter_u64_t rack_tlp_retran;
222 counter_u64_t rack_tlp_retran_bytes;
223 counter_u64_t rack_tlp_retran_fail;
224 counter_u64_t rack_to_tot;
225 counter_u64_t rack_to_arm_rack;
226 counter_u64_t rack_to_arm_tlp;
227 counter_u64_t rack_to_alloc;
228 counter_u64_t rack_to_alloc_hard;
229 counter_u64_t rack_to_alloc_emerg;
230 
231 counter_u64_t rack_sack_proc_all;
232 counter_u64_t rack_sack_proc_short;
233 counter_u64_t rack_sack_proc_restart;
234 counter_u64_t rack_runt_sacks;
235 counter_u64_t rack_used_tlpmethod;
236 counter_u64_t rack_used_tlpmethod2;
237 counter_u64_t rack_enter_tlp_calc;
238 counter_u64_t rack_input_idle_reduces;
239 counter_u64_t rack_tlp_does_nada;
240 
241 /* Temp CPU counters */
242 counter_u64_t rack_find_high;
243 
244 counter_u64_t rack_progress_drops;
245 counter_u64_t rack_out_size[TCP_MSS_ACCT_SIZE];
246 counter_u64_t rack_opts_arry[RACK_OPTS_SIZE];
247 
248 static void
249 rack_log_progress_event(struct tcp_rack *rack, struct tcpcb *tp, uint32_t tick,  int event, int line);
250 
251 static int
252 rack_process_ack(struct mbuf *m, struct tcphdr *th,
253     struct socket *so, struct tcpcb *tp, struct tcpopt *to,
254     uint32_t tiwin, int32_t tlen, int32_t * ofia, int32_t thflags, int32_t * ret_val);
255 static int
256 rack_process_data(struct mbuf *m, struct tcphdr *th,
257     struct socket *so, struct tcpcb *tp, int32_t drop_hdrlen, int32_t tlen,
258     uint32_t tiwin, int32_t thflags, int32_t nxt_pkt);
259 static void
260 rack_ack_received(struct tcpcb *tp, struct tcp_rack *rack,
261     struct tcphdr *th, uint16_t nsegs, uint16_t type, int32_t recovery);
262 static struct rack_sendmap *rack_alloc(struct tcp_rack *rack);
263 static struct rack_sendmap *
264 rack_check_recovery_mode(struct tcpcb *tp,
265     uint32_t tsused);
266 static void
267 rack_cong_signal(struct tcpcb *tp, struct tcphdr *th,
268     uint32_t type);
269 static void rack_counter_destroy(void);
270 static int
271 rack_ctloutput(struct socket *so, struct sockopt *sopt,
272     struct inpcb *inp, struct tcpcb *tp);
273 static int32_t rack_ctor(void *mem, int32_t size, void *arg, int32_t how);
274 static void
275 rack_do_segment(struct mbuf *m, struct tcphdr *th,
276     struct socket *so, struct tcpcb *tp, int32_t drop_hdrlen, int32_t tlen,
277     uint8_t iptos);
278 static void rack_dtor(void *mem, int32_t size, void *arg);
279 static void
280 rack_earlier_retran(struct tcpcb *tp, struct rack_sendmap *rsm,
281     uint32_t t, uint32_t cts);
282 static struct rack_sendmap *
283 rack_find_high_nonack(struct tcp_rack *rack,
284     struct rack_sendmap *rsm);
285 static struct rack_sendmap *rack_find_lowest_rsm(struct tcp_rack *rack);
286 static void rack_free(struct tcp_rack *rack, struct rack_sendmap *rsm);
287 static void rack_fini(struct tcpcb *tp, int32_t tcb_is_purged);
288 static int
289 rack_get_sockopt(struct socket *so, struct sockopt *sopt,
290     struct inpcb *inp, struct tcpcb *tp, struct tcp_rack *rack);
291 static int32_t rack_handoff_ok(struct tcpcb *tp);
292 static int32_t rack_init(struct tcpcb *tp);
293 static void rack_init_sysctls(void);
294 static void
295 rack_log_ack(struct tcpcb *tp, struct tcpopt *to,
296     struct tcphdr *th);
297 static void
298 rack_log_output(struct tcpcb *tp, struct tcpopt *to, int32_t len,
299     uint32_t seq_out, uint8_t th_flags, int32_t err, uint32_t ts,
300     uint8_t pass, struct rack_sendmap *hintrsm);
301 static void
302 rack_log_sack_passed(struct tcpcb *tp, struct tcp_rack *rack,
303     struct rack_sendmap *rsm);
304 static void rack_log_to_event(struct tcp_rack *rack, int32_t to_num);
305 static int32_t rack_output(struct tcpcb *tp);
306 static void
307 rack_hpts_do_segment(struct mbuf *m, struct tcphdr *th,
308     struct socket *so, struct tcpcb *tp, int32_t drop_hdrlen, int32_t tlen,
309     uint8_t iptos, int32_t nxt_pkt, struct timeval *tv);
310 
311 static uint32_t
312 rack_proc_sack_blk(struct tcpcb *tp, struct tcp_rack *rack,
313     struct sackblk *sack, struct tcpopt *to, struct rack_sendmap **prsm,
314     uint32_t cts);
315 static void rack_post_recovery(struct tcpcb *tp, struct tcphdr *th);
316 static void rack_remxt_tmr(struct tcpcb *tp);
317 static int
318 rack_set_sockopt(struct socket *so, struct sockopt *sopt,
319     struct inpcb *inp, struct tcpcb *tp, struct tcp_rack *rack);
320 static void rack_set_state(struct tcpcb *tp, struct tcp_rack *rack);
321 static int32_t rack_stopall(struct tcpcb *tp);
322 static void
323 rack_timer_activate(struct tcpcb *tp, uint32_t timer_type,
324     uint32_t delta);
325 static int32_t rack_timer_active(struct tcpcb *tp, uint32_t timer_type);
326 static void rack_timer_cancel(struct tcpcb *tp, struct tcp_rack *rack, uint32_t cts, int line);
327 static void rack_timer_stop(struct tcpcb *tp, uint32_t timer_type);
328 static uint32_t
329 rack_update_entry(struct tcpcb *tp, struct tcp_rack *rack,
330     struct rack_sendmap *rsm, uint32_t ts, int32_t * lenp);
331 static void
332 rack_update_rsm(struct tcpcb *tp, struct tcp_rack *rack,
333     struct rack_sendmap *rsm, uint32_t ts);
334 static int
335 rack_update_rtt(struct tcpcb *tp, struct tcp_rack *rack,
336     struct rack_sendmap *rsm, struct tcpopt *to, uint32_t cts, int32_t ack_type);
337 static int32_t tcp_addrack(module_t mod, int32_t type, void *data);
338 static void
339 rack_challenge_ack(struct mbuf *m, struct tcphdr *th,
340     struct tcpcb *tp, int32_t * ret_val);
341 static int
342 rack_do_close_wait(struct mbuf *m, struct tcphdr *th,
343     struct socket *so, struct tcpcb *tp, struct tcpopt *to, int32_t drop_hdrlen,
344     int32_t tlen, uint32_t tiwin, int32_t thflags, int32_t nxt_pkt);
345 static int
346 rack_do_closing(struct mbuf *m, struct tcphdr *th,
347     struct socket *so, struct tcpcb *tp, struct tcpopt *to, int32_t drop_hdrlen,
348     int32_t tlen, uint32_t tiwin, int32_t thflags, int32_t nxt_pkt);
349 static void
350 rack_do_drop(struct mbuf *m, struct tcpcb *tp);
351 static void
352 rack_do_dropafterack(struct mbuf *m, struct tcpcb *tp,
353     struct tcphdr *th, int32_t thflags, int32_t tlen, int32_t * ret_val);
354 static void
355 rack_do_dropwithreset(struct mbuf *m, struct tcpcb *tp,
356 	struct tcphdr *th, int32_t rstreason, int32_t tlen);
357 static int
358 rack_do_established(struct mbuf *m, struct tcphdr *th,
359     struct socket *so, struct tcpcb *tp, struct tcpopt *to, int32_t drop_hdrlen,
360     int32_t tlen, uint32_t tiwin, int32_t thflags, int32_t nxt_pkt);
361 static int
362 rack_do_fastnewdata(struct mbuf *m, struct tcphdr *th,
363     struct socket *so, struct tcpcb *tp, struct tcpopt *to, int32_t drop_hdrlen,
364     int32_t tlen, uint32_t tiwin, int32_t nxt_pkt);
365 static int
366 rack_do_fin_wait_1(struct mbuf *m, struct tcphdr *th,
367     struct socket *so, struct tcpcb *tp, struct tcpopt *to, int32_t drop_hdrlen,
368     int32_t tlen, uint32_t tiwin, int32_t thflags, int32_t nxt_pkt);
369 static int
370 rack_do_fin_wait_2(struct mbuf *m, struct tcphdr *th,
371     struct socket *so, struct tcpcb *tp, struct tcpopt *to, int32_t drop_hdrlen,
372     int32_t tlen, uint32_t tiwin, int32_t thflags, int32_t nxt_pkt);
373 static int
374 rack_do_lastack(struct mbuf *m, struct tcphdr *th,
375     struct socket *so, struct tcpcb *tp, struct tcpopt *to, int32_t drop_hdrlen,
376     int32_t tlen, uint32_t tiwin, int32_t thflags, int32_t nxt_pkt);
377 static int
378 rack_do_syn_recv(struct mbuf *m, struct tcphdr *th,
379     struct socket *so, struct tcpcb *tp, struct tcpopt *to, int32_t drop_hdrlen,
380     int32_t tlen, uint32_t tiwin, int32_t thflags, int32_t nxt_pkt);
381 static int
382 rack_do_syn_sent(struct mbuf *m, struct tcphdr *th,
383     struct socket *so, struct tcpcb *tp, struct tcpopt *to, int32_t drop_hdrlen,
384     int32_t tlen, uint32_t tiwin, int32_t thflags, int32_t nxt_pkt);
385 static int
386 rack_drop_checks(struct tcpopt *to, struct mbuf *m,
387     struct tcphdr *th, struct tcpcb *tp, int32_t * tlenp, int32_t * thf,
388     int32_t * drop_hdrlen, int32_t * ret_val);
389 static int
390 rack_process_rst(struct mbuf *m, struct tcphdr *th,
391     struct socket *so, struct tcpcb *tp);
392 struct rack_sendmap *
393 tcp_rack_output(struct tcpcb *tp, struct tcp_rack *rack,
394     uint32_t tsused);
395 static void tcp_rack_xmit_timer(struct tcp_rack *rack, int32_t rtt);
396 static void
397      tcp_rack_partialack(struct tcpcb *tp, struct tcphdr *th);
398 
399 static int
400 rack_ts_check(struct mbuf *m, struct tcphdr *th,
401     struct tcpcb *tp, int32_t tlen, int32_t thflags, int32_t * ret_val);
402 
403 int32_t rack_clear_counter=0;
404 
405 
406 static int
407 sysctl_rack_clear(SYSCTL_HANDLER_ARGS)
408 {
409 	uint32_t stat;
410 	int32_t error;
411 
412 	error = SYSCTL_OUT(req, &rack_clear_counter, sizeof(uint32_t));
413 	if (error || req->newptr == NULL)
414 		return error;
415 
416 	error = SYSCTL_IN(req, &stat, sizeof(uint32_t));
417 	if (error)
418 		return (error);
419 	if (stat == 1) {
420 #ifdef INVARIANTS
421 		printf("Clearing RACK counters\n");
422 #endif
423 		counter_u64_zero(rack_badfr);
424 		counter_u64_zero(rack_badfr_bytes);
425 		counter_u64_zero(rack_rtm_prr_retran);
426 		counter_u64_zero(rack_rtm_prr_newdata);
427 		counter_u64_zero(rack_timestamp_mismatch);
428 		counter_u64_zero(rack_reorder_seen);
429 		counter_u64_zero(rack_tlp_tot);
430 		counter_u64_zero(rack_tlp_newdata);
431 		counter_u64_zero(rack_tlp_retran);
432 		counter_u64_zero(rack_tlp_retran_bytes);
433 		counter_u64_zero(rack_tlp_retran_fail);
434 		counter_u64_zero(rack_to_tot);
435 		counter_u64_zero(rack_to_arm_rack);
436 		counter_u64_zero(rack_to_arm_tlp);
437 		counter_u64_zero(rack_paced_segments);
438 		counter_u64_zero(rack_unpaced_segments);
439 		counter_u64_zero(rack_saw_enobuf);
440 		counter_u64_zero(rack_saw_enetunreach);
441 		counter_u64_zero(rack_to_alloc_hard);
442 		counter_u64_zero(rack_to_alloc_emerg);
443 		counter_u64_zero(rack_sack_proc_all);
444 		counter_u64_zero(rack_sack_proc_short);
445 		counter_u64_zero(rack_sack_proc_restart);
446 		counter_u64_zero(rack_to_alloc);
447 		counter_u64_zero(rack_find_high);
448 		counter_u64_zero(rack_runt_sacks);
449 		counter_u64_zero(rack_used_tlpmethod);
450 		counter_u64_zero(rack_used_tlpmethod2);
451 		counter_u64_zero(rack_enter_tlp_calc);
452 		counter_u64_zero(rack_progress_drops);
453 		counter_u64_zero(rack_tlp_does_nada);
454 	}
455 	rack_clear_counter = 0;
456 	return (0);
457 }
458 
459 
460 
461 static void
462 rack_init_sysctls()
463 {
464 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
465 	    SYSCTL_CHILDREN(rack_sysctl_root),
466 	    OID_AUTO, "rate_sample_method", CTLFLAG_RW,
467 	    &rack_rate_sample_method , USE_RTT_LOW,
468 	    "What method should we use for rate sampling 0=high, 1=low ");
469 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
470 	    SYSCTL_CHILDREN(rack_sysctl_root),
471 	    OID_AUTO, "data_after_close", CTLFLAG_RW,
472 	    &rack_ignore_data_after_close, 0,
473 	    "Do we hold off sending a RST until all pending data is ack'd");
474 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
475 	    SYSCTL_CHILDREN(rack_sysctl_root),
476 	    OID_AUTO, "tlpmethod", CTLFLAG_RW,
477 	    &rack_tlp_threshold_use, TLP_USE_TWO_ONE,
478 	    "What method do we do for TLP time calc 0=no-de-ack-comp, 1=ID, 2=2.1, 3=2.2");
479 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
480 	    SYSCTL_CHILDREN(rack_sysctl_root),
481 	    OID_AUTO, "min_pace_time", CTLFLAG_RW,
482 	    &rack_min_pace_time, 0,
483 	    "Should we enforce a minimum pace time of 1ms");
484 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
485 	    SYSCTL_CHILDREN(rack_sysctl_root),
486 	    OID_AUTO, "min_pace_segs", CTLFLAG_RW,
487 	    &rack_min_pace_time_seg_req, 6,
488 	    "How many segments have to be in the len to enforce min-pace-time");
489 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
490 	    SYSCTL_CHILDREN(rack_sysctl_root),
491 	    OID_AUTO, "idle_reduce_high", CTLFLAG_RW,
492 	    &rack_reduce_largest_on_idle, 0,
493 	    "Should we reduce the largest cwnd seen to IW on idle reduction");
494 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
495 	    SYSCTL_CHILDREN(rack_sysctl_root),
496 	    OID_AUTO, "bb_verbose", CTLFLAG_RW,
497 	    &rack_verbose_logging, 0,
498 	    "Should RACK black box logging be verbose");
499 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
500 	    SYSCTL_CHILDREN(rack_sysctl_root),
501 	    OID_AUTO, "sackfiltering", CTLFLAG_RW,
502 	    &rack_use_sack_filter, 1,
503 	    "Do we use sack filtering?");
504 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
505 	    SYSCTL_CHILDREN(rack_sysctl_root),
506 	    OID_AUTO, "delayed_ack", CTLFLAG_RW,
507 	    &rack_delayed_ack_time, 200,
508 	    "Delayed ack time (200ms)");
509 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
510 	    SYSCTL_CHILDREN(rack_sysctl_root),
511 	    OID_AUTO, "tlpminto", CTLFLAG_RW,
512 	    &rack_tlp_min, 10,
513 	    "TLP minimum timeout per the specification (10ms)");
514 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
515 	    SYSCTL_CHILDREN(rack_sysctl_root),
516 	    OID_AUTO, "precache", CTLFLAG_RW,
517 	    &rack_precache, 0,
518 	    "Where should we precache the mcopy (0 is not at all)");
519 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
520 	    SYSCTL_CHILDREN(rack_sysctl_root),
521 	    OID_AUTO, "sblklimit", CTLFLAG_RW,
522 	    &rack_sack_block_limit, 128,
523 	    "When do we start paying attention to small sack blocks");
524 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
525 	    SYSCTL_CHILDREN(rack_sysctl_root),
526 	    OID_AUTO, "send_oldest", CTLFLAG_RW,
527 	    &rack_always_send_oldest, 1,
528 	    "Should we always send the oldest TLP and RACK-TLP");
529 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
530 	    SYSCTL_CHILDREN(rack_sysctl_root),
531 	    OID_AUTO, "rack_tlp_in_recovery", CTLFLAG_RW,
532 	    &rack_tlp_in_recovery, 1,
533 	    "Can we do a TLP during recovery?");
534 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
535 	    SYSCTL_CHILDREN(rack_sysctl_root),
536 	    OID_AUTO, "rack_tlimit", CTLFLAG_RW,
537 	    &rack_limited_retran, 0,
538 	    "How many times can a rack timeout drive out sends");
539 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
540 	    SYSCTL_CHILDREN(rack_sysctl_root),
541 	    OID_AUTO, "minrto", CTLFLAG_RW,
542 	    &rack_rto_min, 0,
543 	    "Minimum RTO in ms -- set with caution below 1000 due to TLP");
544 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
545 	    SYSCTL_CHILDREN(rack_sysctl_root),
546 	    OID_AUTO, "maxrto", CTLFLAG_RW,
547 	    &rack_rto_max, 0,
548 	    "Maxiumum RTO in ms -- should be at least as large as min_rto");
549 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
550 	    SYSCTL_CHILDREN(rack_sysctl_root),
551 	    OID_AUTO, "tlp_retry", CTLFLAG_RW,
552 	    &rack_tlp_max_resend, 2,
553 	    "How many times does TLP retry a single segment or multiple with no ACK");
554 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
555 	    SYSCTL_CHILDREN(rack_sysctl_root),
556 	    OID_AUTO, "recovery_loss_prop", CTLFLAG_RW,
557 	    &rack_use_proportional_reduce, 0,
558 	    "Should we proportionaly reduce cwnd based on the number of losses ");
559 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
560 	    SYSCTL_CHILDREN(rack_sysctl_root),
561 	    OID_AUTO, "recovery_prop", CTLFLAG_RW,
562 	    &rack_proportional_rate, 10,
563 	    "What percent reduction per loss");
564 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
565 	    SYSCTL_CHILDREN(rack_sysctl_root),
566 	    OID_AUTO, "tlp_cwnd_flag", CTLFLAG_RW,
567 	    &rack_lower_cwnd_at_tlp, 0,
568 	    "When a TLP completes a retran should we enter recovery?");
569 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
570 	    SYSCTL_CHILDREN(rack_sysctl_root),
571 	    OID_AUTO, "hptsi_reduces", CTLFLAG_RW,
572 	    &rack_slot_reduction, 4,
573 	    "When setting a slot should we reduce by divisor");
574 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
575 	    SYSCTL_CHILDREN(rack_sysctl_root),
576 	    OID_AUTO, "hptsi_every_seg", CTLFLAG_RW,
577 	    &rack_pace_every_seg, 1,
578 	    "Should we pace out every segment hptsi");
579 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
580 	    SYSCTL_CHILDREN(rack_sysctl_root),
581 	    OID_AUTO, "hptsi_seg_max", CTLFLAG_RW,
582 	    &rack_hptsi_segments, 6,
583 	    "Should we pace out only a limited size of segments");
584 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
585 	    SYSCTL_CHILDREN(rack_sysctl_root),
586 	    OID_AUTO, "prr_sendalot", CTLFLAG_RW,
587 	    &rack_send_a_lot_in_prr, 1,
588 	    "Send a lot in prr");
589 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
590 	    SYSCTL_CHILDREN(rack_sysctl_root),
591 	    OID_AUTO, "minto", CTLFLAG_RW,
592 	    &rack_min_to, 1,
593 	    "Minimum rack timeout in milliseconds");
594 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
595 	    SYSCTL_CHILDREN(rack_sysctl_root),
596 	    OID_AUTO, "earlyrecoveryseg", CTLFLAG_RW,
597 	    &rack_early_recovery_max_seg, 6,
598 	    "Max segments in early recovery");
599 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
600 	    SYSCTL_CHILDREN(rack_sysctl_root),
601 	    OID_AUTO, "earlyrecovery", CTLFLAG_RW,
602 	    &rack_early_recovery, 1,
603 	    "Do we do early recovery with rack");
604 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
605 	    SYSCTL_CHILDREN(rack_sysctl_root),
606 	    OID_AUTO, "reorder_thresh", CTLFLAG_RW,
607 	    &rack_reorder_thresh, 2,
608 	    "What factor for rack will be added when seeing reordering (shift right)");
609 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
610 	    SYSCTL_CHILDREN(rack_sysctl_root),
611 	    OID_AUTO, "rtt_tlp_thresh", CTLFLAG_RW,
612 	    &rack_tlp_thresh, 1,
613 	    "what divisor for TLP rtt/retran will be added (1=rtt, 2=1/2 rtt etc)");
614 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
615 	    SYSCTL_CHILDREN(rack_sysctl_root),
616 	    OID_AUTO, "reorder_fade", CTLFLAG_RW,
617 	    &rack_reorder_fade, 0,
618 	    "Does reorder detection fade, if so how many ms (0 means never)");
619 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
620 	    SYSCTL_CHILDREN(rack_sysctl_root),
621 	    OID_AUTO, "pktdelay", CTLFLAG_RW,
622 	    &rack_pkt_delay, 1,
623 	    "Extra RACK time (in ms) besides reordering thresh");
624 	SYSCTL_ADD_S32(&rack_sysctl_ctx,
625 	    SYSCTL_CHILDREN(rack_sysctl_root),
626 	    OID_AUTO, "inc_var", CTLFLAG_RW,
627 	    &rack_inc_var, 0,
628 	    "Should rack add to the TLP timer the variance in rtt calculation");
629 	rack_badfr = counter_u64_alloc(M_WAITOK);
630 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
631 	    SYSCTL_CHILDREN(rack_sysctl_root),
632 	    OID_AUTO, "badfr", CTLFLAG_RD,
633 	    &rack_badfr, "Total number of bad FRs");
634 	rack_badfr_bytes = counter_u64_alloc(M_WAITOK);
635 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
636 	    SYSCTL_CHILDREN(rack_sysctl_root),
637 	    OID_AUTO, "badfr_bytes", CTLFLAG_RD,
638 	    &rack_badfr_bytes, "Total number of bad FRs");
639 	rack_rtm_prr_retran = counter_u64_alloc(M_WAITOK);
640 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
641 	    SYSCTL_CHILDREN(rack_sysctl_root),
642 	    OID_AUTO, "prrsndret", CTLFLAG_RD,
643 	    &rack_rtm_prr_retran,
644 	    "Total number of prr based retransmits");
645 	rack_rtm_prr_newdata = counter_u64_alloc(M_WAITOK);
646 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
647 	    SYSCTL_CHILDREN(rack_sysctl_root),
648 	    OID_AUTO, "prrsndnew", CTLFLAG_RD,
649 	    &rack_rtm_prr_newdata,
650 	    "Total number of prr based new transmits");
651 	rack_timestamp_mismatch = counter_u64_alloc(M_WAITOK);
652 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
653 	    SYSCTL_CHILDREN(rack_sysctl_root),
654 	    OID_AUTO, "tsnf", CTLFLAG_RD,
655 	    &rack_timestamp_mismatch,
656 	    "Total number of timestamps that we could not find the reported ts");
657 	rack_find_high = counter_u64_alloc(M_WAITOK);
658 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
659 	    SYSCTL_CHILDREN(rack_sysctl_root),
660 	    OID_AUTO, "findhigh", CTLFLAG_RD,
661 	    &rack_find_high,
662 	    "Total number of FIN causing find-high");
663 	rack_reorder_seen = counter_u64_alloc(M_WAITOK);
664 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
665 	    SYSCTL_CHILDREN(rack_sysctl_root),
666 	    OID_AUTO, "reordering", CTLFLAG_RD,
667 	    &rack_reorder_seen,
668 	    "Total number of times we added delay due to reordering");
669 	rack_tlp_tot = counter_u64_alloc(M_WAITOK);
670 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
671 	    SYSCTL_CHILDREN(rack_sysctl_root),
672 	    OID_AUTO, "tlp_to_total", CTLFLAG_RD,
673 	    &rack_tlp_tot,
674 	    "Total number of tail loss probe expirations");
675 	rack_tlp_newdata = counter_u64_alloc(M_WAITOK);
676 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
677 	    SYSCTL_CHILDREN(rack_sysctl_root),
678 	    OID_AUTO, "tlp_new", CTLFLAG_RD,
679 	    &rack_tlp_newdata,
680 	    "Total number of tail loss probe sending new data");
681 
682 	rack_tlp_retran = counter_u64_alloc(M_WAITOK);
683 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
684 	    SYSCTL_CHILDREN(rack_sysctl_root),
685 	    OID_AUTO, "tlp_retran", CTLFLAG_RD,
686 	    &rack_tlp_retran,
687 	    "Total number of tail loss probe sending retransmitted data");
688 	rack_tlp_retran_bytes = counter_u64_alloc(M_WAITOK);
689 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
690 	    SYSCTL_CHILDREN(rack_sysctl_root),
691 	    OID_AUTO, "tlp_retran_bytes", CTLFLAG_RD,
692 	    &rack_tlp_retran_bytes,
693 	    "Total bytes of tail loss probe sending retransmitted data");
694 	rack_tlp_retran_fail = counter_u64_alloc(M_WAITOK);
695 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
696 	    SYSCTL_CHILDREN(rack_sysctl_root),
697 	    OID_AUTO, "tlp_retran_fail", CTLFLAG_RD,
698 	    &rack_tlp_retran_fail,
699 	    "Total number of tail loss probe sending retransmitted data that failed (wait for t3)");
700 	rack_to_tot = counter_u64_alloc(M_WAITOK);
701 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
702 	    SYSCTL_CHILDREN(rack_sysctl_root),
703 	    OID_AUTO, "rack_to_tot", CTLFLAG_RD,
704 	    &rack_to_tot,
705 	    "Total number of times the rack to expired?");
706 	rack_to_arm_rack = counter_u64_alloc(M_WAITOK);
707 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
708 	    SYSCTL_CHILDREN(rack_sysctl_root),
709 	    OID_AUTO, "arm_rack", CTLFLAG_RD,
710 	    &rack_to_arm_rack,
711 	    "Total number of times the rack timer armed?");
712 	rack_to_arm_tlp = counter_u64_alloc(M_WAITOK);
713 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
714 	    SYSCTL_CHILDREN(rack_sysctl_root),
715 	    OID_AUTO, "arm_tlp", CTLFLAG_RD,
716 	    &rack_to_arm_tlp,
717 	    "Total number of times the tlp timer armed?");
718 	rack_paced_segments = counter_u64_alloc(M_WAITOK);
719 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
720 	    SYSCTL_CHILDREN(rack_sysctl_root),
721 	    OID_AUTO, "paced", CTLFLAG_RD,
722 	    &rack_paced_segments,
723 	    "Total number of times a segment send caused hptsi");
724 	rack_unpaced_segments = counter_u64_alloc(M_WAITOK);
725 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
726 	    SYSCTL_CHILDREN(rack_sysctl_root),
727 	    OID_AUTO, "unpaced", CTLFLAG_RD,
728 	    &rack_unpaced_segments,
729 	    "Total number of times a segment did not cause hptsi");
730 	rack_saw_enobuf = counter_u64_alloc(M_WAITOK);
731 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
732 	    SYSCTL_CHILDREN(rack_sysctl_root),
733 	    OID_AUTO, "saw_enobufs", CTLFLAG_RD,
734 	    &rack_saw_enobuf,
735 	    "Total number of times a segment did not cause hptsi");
736 	rack_saw_enetunreach = counter_u64_alloc(M_WAITOK);
737 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
738 	    SYSCTL_CHILDREN(rack_sysctl_root),
739 	    OID_AUTO, "saw_enetunreach", CTLFLAG_RD,
740 	    &rack_saw_enetunreach,
741 	    "Total number of times a segment did not cause hptsi");
742 	rack_to_alloc = counter_u64_alloc(M_WAITOK);
743 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
744 	    SYSCTL_CHILDREN(rack_sysctl_root),
745 	    OID_AUTO, "allocs", CTLFLAG_RD,
746 	    &rack_to_alloc,
747 	    "Total allocations of tracking structures");
748 	rack_to_alloc_hard = counter_u64_alloc(M_WAITOK);
749 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
750 	    SYSCTL_CHILDREN(rack_sysctl_root),
751 	    OID_AUTO, "allochard", CTLFLAG_RD,
752 	    &rack_to_alloc_hard,
753 	    "Total allocations done with sleeping the hard way");
754 	rack_to_alloc_emerg = counter_u64_alloc(M_WAITOK);
755 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
756 	    SYSCTL_CHILDREN(rack_sysctl_root),
757 	    OID_AUTO, "allocemerg", CTLFLAG_RD,
758 	    &rack_to_alloc_emerg,
759 	    "Total alocations done from emergency cache");
760 	rack_sack_proc_all = counter_u64_alloc(M_WAITOK);
761 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
762 	    SYSCTL_CHILDREN(rack_sysctl_root),
763 	    OID_AUTO, "sack_long", CTLFLAG_RD,
764 	    &rack_sack_proc_all,
765 	    "Total times we had to walk whole list for sack processing");
766 
767 	rack_sack_proc_restart = counter_u64_alloc(M_WAITOK);
768 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
769 	    SYSCTL_CHILDREN(rack_sysctl_root),
770 	    OID_AUTO, "sack_restart", CTLFLAG_RD,
771 	    &rack_sack_proc_restart,
772 	    "Total times we had to walk whole list due to a restart");
773 	rack_sack_proc_short = counter_u64_alloc(M_WAITOK);
774 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
775 	    SYSCTL_CHILDREN(rack_sysctl_root),
776 	    OID_AUTO, "sack_short", CTLFLAG_RD,
777 	    &rack_sack_proc_short,
778 	    "Total times we took shortcut for sack processing");
779 	rack_enter_tlp_calc = counter_u64_alloc(M_WAITOK);
780 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
781 	    SYSCTL_CHILDREN(rack_sysctl_root),
782 	    OID_AUTO, "tlp_calc_entered", CTLFLAG_RD,
783 	    &rack_enter_tlp_calc,
784 	    "Total times we called calc-tlp");
785 	rack_used_tlpmethod = counter_u64_alloc(M_WAITOK);
786 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
787 	    SYSCTL_CHILDREN(rack_sysctl_root),
788 	    OID_AUTO, "hit_tlp_method", CTLFLAG_RD,
789 	    &rack_used_tlpmethod,
790 	    "Total number of runt sacks");
791 	rack_used_tlpmethod2 = counter_u64_alloc(M_WAITOK);
792 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
793 	    SYSCTL_CHILDREN(rack_sysctl_root),
794 	    OID_AUTO, "hit_tlp_method2", CTLFLAG_RD,
795 	    &rack_used_tlpmethod2,
796 	    "Total number of runt sacks 2");
797 	rack_runt_sacks = counter_u64_alloc(M_WAITOK);
798 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
799 	    SYSCTL_CHILDREN(rack_sysctl_root),
800 	    OID_AUTO, "runtsacks", CTLFLAG_RD,
801 	    &rack_runt_sacks,
802 	    "Total number of runt sacks");
803 	rack_progress_drops = counter_u64_alloc(M_WAITOK);
804 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
805 	    SYSCTL_CHILDREN(rack_sysctl_root),
806 	    OID_AUTO, "prog_drops", CTLFLAG_RD,
807 	    &rack_progress_drops,
808 	    "Total number of progress drops");
809 	rack_input_idle_reduces = counter_u64_alloc(M_WAITOK);
810 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
811 	    SYSCTL_CHILDREN(rack_sysctl_root),
812 	    OID_AUTO, "idle_reduce_oninput", CTLFLAG_RD,
813 	    &rack_input_idle_reduces,
814 	    "Total number of idle reductions on input");
815 	rack_tlp_does_nada = counter_u64_alloc(M_WAITOK);
816 	SYSCTL_ADD_COUNTER_U64(&rack_sysctl_ctx,
817 	    SYSCTL_CHILDREN(rack_sysctl_root),
818 	    OID_AUTO, "tlp_nada", CTLFLAG_RD,
819 	    &rack_tlp_does_nada,
820 	    "Total number of nada tlp calls");
821 	COUNTER_ARRAY_ALLOC(rack_out_size, TCP_MSS_ACCT_SIZE, M_WAITOK);
822 	SYSCTL_ADD_COUNTER_U64_ARRAY(&rack_sysctl_ctx, SYSCTL_CHILDREN(rack_sysctl_root),
823 	    OID_AUTO, "outsize", CTLFLAG_RD,
824 	    rack_out_size, TCP_MSS_ACCT_SIZE, "MSS send sizes");
825 	COUNTER_ARRAY_ALLOC(rack_opts_arry, RACK_OPTS_SIZE, M_WAITOK);
826 	SYSCTL_ADD_COUNTER_U64_ARRAY(&rack_sysctl_ctx, SYSCTL_CHILDREN(rack_sysctl_root),
827 	    OID_AUTO, "opts", CTLFLAG_RD,
828 	    rack_opts_arry, RACK_OPTS_SIZE, "RACK Option Stats");
829 	SYSCTL_ADD_PROC(&rack_sysctl_ctx,
830 	    SYSCTL_CHILDREN(rack_sysctl_root),
831 	    OID_AUTO, "clear", CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_MPSAFE,
832 	    &rack_clear_counter, 0, sysctl_rack_clear, "IU", "Clear counters");
833 }
834 
835 static inline int32_t
836 rack_progress_timeout_check(struct tcpcb *tp)
837 {
838 	if (tp->t_maxunacktime && tp->t_acktime && TSTMP_GT(ticks, tp->t_acktime)) {
839 		if ((ticks - tp->t_acktime) >= tp->t_maxunacktime) {
840 			/*
841 			 * There is an assumption that the caller
842 			 * will drop the connection so we will
843 			 * increment the counters here.
844 			 */
845 			struct tcp_rack *rack;
846 			rack = (struct tcp_rack *)tp->t_fb_ptr;
847 			counter_u64_add(rack_progress_drops, 1);
848 #ifdef NETFLIX_STATS
849 			TCPSTAT_INC(tcps_progdrops);
850 #endif
851 			rack_log_progress_event(rack, tp, ticks, PROGRESS_DROP, __LINE__);
852 			return (1);
853 		}
854 	}
855 	return (0);
856 }
857 
858 
859 static void
860 rack_log_to_start(struct tcp_rack *rack, uint32_t cts, uint32_t to, int32_t slot, uint8_t which)
861 {
862 	if (rack->rc_tp->t_logstate != TCP_LOG_STATE_OFF) {
863 		union tcp_log_stackspecific log;
864 
865 		memset(&log.u_bbr, 0, sizeof(log.u_bbr));
866 		log.u_bbr.flex1 = TICKS_2_MSEC(rack->rc_tp->t_srtt >> TCP_RTT_SHIFT);
867 		log.u_bbr.flex2 = to;
868 		log.u_bbr.flex3 = rack->r_ctl.rc_hpts_flags;
869 		log.u_bbr.flex4 = slot;
870 		log.u_bbr.flex5 = rack->rc_inp->inp_hptsslot;
871 		log.u_bbr.flex6 = rack->rc_tp->t_rxtcur;
872 		log.u_bbr.flex8 = which;
873 		log.u_bbr.inhpts = rack->rc_inp->inp_in_hpts;
874 		log.u_bbr.ininput = rack->rc_inp->inp_in_input;
875 		TCP_LOG_EVENT(rack->rc_tp, NULL,
876 		    &rack->rc_inp->inp_socket->so_rcv,
877 		    &rack->rc_inp->inp_socket->so_snd,
878 		    BBR_LOG_TIMERSTAR, 0,
879 		    0, &log, false);
880 	}
881 }
882 
883 static void
884 rack_log_to_event(struct tcp_rack *rack, int32_t to_num)
885 {
886 	if (rack->rc_tp->t_logstate != TCP_LOG_STATE_OFF) {
887 		union tcp_log_stackspecific log;
888 
889 		memset(&log.u_bbr, 0, sizeof(log.u_bbr));
890 		log.u_bbr.inhpts = rack->rc_inp->inp_in_hpts;
891 		log.u_bbr.ininput = rack->rc_inp->inp_in_input;
892 		log.u_bbr.flex8 = to_num;
893 		log.u_bbr.flex1 = rack->r_ctl.rc_rack_min_rtt;
894 		log.u_bbr.flex2 = rack->rc_rack_rtt;
895 		TCP_LOG_EVENT(rack->rc_tp, NULL,
896 		    &rack->rc_inp->inp_socket->so_rcv,
897 		    &rack->rc_inp->inp_socket->so_snd,
898 		    BBR_LOG_RTO, 0,
899 		    0, &log, false);
900 	}
901 }
902 
903 static void
904 rack_log_rtt_upd(struct tcpcb *tp, struct tcp_rack *rack, int32_t t,
905     uint32_t o_srtt, uint32_t o_var)
906 {
907 	if (tp->t_logstate != TCP_LOG_STATE_OFF) {
908 		union tcp_log_stackspecific log;
909 
910 		memset(&log.u_bbr, 0, sizeof(log.u_bbr));
911 		log.u_bbr.inhpts = rack->rc_inp->inp_in_hpts;
912 		log.u_bbr.ininput = rack->rc_inp->inp_in_input;
913 		log.u_bbr.flex1 = t;
914 		log.u_bbr.flex2 = o_srtt;
915 		log.u_bbr.flex3 = o_var;
916 		log.u_bbr.flex4 = rack->r_ctl.rack_rs.rs_rtt_lowest;
917 		log.u_bbr.flex5 = rack->r_ctl.rack_rs.rs_rtt_highest;
918 		log.u_bbr.flex6 = rack->r_ctl.rack_rs.rs_rtt_cnt;
919 		log.u_bbr.rttProp = rack->r_ctl.rack_rs.rs_rtt_tot;
920 		log.u_bbr.flex8 = rack->r_ctl.rc_rate_sample_method;
921 		TCP_LOG_EVENT(tp, NULL,
922 		    &rack->rc_inp->inp_socket->so_rcv,
923 		    &rack->rc_inp->inp_socket->so_snd,
924 		    BBR_LOG_BBRRTT, 0,
925 		    0, &log, false);
926 	}
927 }
928 
929 static void
930 rack_log_rtt_sample(struct tcp_rack *rack, uint32_t rtt)
931 {
932 	/*
933 	 * Log the rtt sample we are
934 	 * applying to the srtt algorithm in
935 	 * useconds.
936 	 */
937 	if (rack->rc_tp->t_logstate != TCP_LOG_STATE_OFF) {
938 		union tcp_log_stackspecific log;
939 		struct timeval tv;
940 
941 		/* Convert our ms to a microsecond */
942 		log.u_bbr.flex1 = rtt * 1000;
943 		log.u_bbr.timeStamp = tcp_get_usecs(&tv);
944 		TCP_LOG_EVENTP(rack->rc_tp, NULL,
945 		    &rack->rc_inp->inp_socket->so_rcv,
946 		    &rack->rc_inp->inp_socket->so_snd,
947 		    TCP_LOG_RTT, 0,
948 		    0, &log, false, &tv);
949 	}
950 }
951 
952 
953 static inline void
954 rack_log_progress_event(struct tcp_rack *rack, struct tcpcb *tp, uint32_t tick,  int event, int line)
955 {
956 	if (rack_verbose_logging && (tp->t_logstate != TCP_LOG_STATE_OFF)) {
957 		union tcp_log_stackspecific log;
958 
959 		memset(&log.u_bbr, 0, sizeof(log.u_bbr));
960 		log.u_bbr.inhpts = rack->rc_inp->inp_in_hpts;
961 		log.u_bbr.ininput = rack->rc_inp->inp_in_input;
962 		log.u_bbr.flex1 = line;
963 		log.u_bbr.flex2 = tick;
964 		log.u_bbr.flex3 = tp->t_maxunacktime;
965 		log.u_bbr.flex4 = tp->t_acktime;
966 		log.u_bbr.flex8 = event;
967 		TCP_LOG_EVENT(tp, NULL,
968 		    &rack->rc_inp->inp_socket->so_rcv,
969 		    &rack->rc_inp->inp_socket->so_snd,
970 		    BBR_LOG_PROGRESS, 0,
971 		    0, &log, false);
972 	}
973 }
974 
975 static void
976 rack_log_type_bbrsnd(struct tcp_rack *rack, uint32_t len, uint32_t slot, uint32_t cts)
977 {
978 	if (rack->rc_tp->t_logstate != TCP_LOG_STATE_OFF) {
979 		union tcp_log_stackspecific log;
980 
981 		memset(&log.u_bbr, 0, sizeof(log.u_bbr));
982 		log.u_bbr.inhpts = rack->rc_inp->inp_in_hpts;
983 		log.u_bbr.ininput = rack->rc_inp->inp_in_input;
984 		log.u_bbr.flex1 = slot;
985 		log.u_bbr.flex7 = (0x0000ffff & rack->r_ctl.rc_hpts_flags);
986 		log.u_bbr.flex8 = rack->rc_in_persist;
987 		TCP_LOG_EVENT(rack->rc_tp, NULL,
988 		    &rack->rc_inp->inp_socket->so_rcv,
989 		    &rack->rc_inp->inp_socket->so_snd,
990 		    BBR_LOG_BBRSND, 0,
991 		    0, &log, false);
992 	}
993 }
994 
995 static void
996 rack_log_doseg_done(struct tcp_rack *rack, uint32_t cts, int32_t nxt_pkt, int32_t did_out, int way_out)
997 {
998 	if (rack->rc_tp->t_logstate != TCP_LOG_STATE_OFF) {
999 		union tcp_log_stackspecific log;
1000 		log.u_bbr.flex1 = did_out;
1001 		log.u_bbr.flex2 = nxt_pkt;
1002 		log.u_bbr.flex3 = way_out;
1003 		log.u_bbr.flex4 = rack->r_ctl.rc_hpts_flags;
1004 		log.u_bbr.flex7 = rack->r_wanted_output;
1005 		log.u_bbr.flex8 = rack->rc_in_persist;
1006 		TCP_LOG_EVENT(rack->rc_tp, NULL,
1007 		    &rack->rc_inp->inp_socket->so_rcv,
1008 		    &rack->rc_inp->inp_socket->so_snd,
1009 		    BBR_LOG_DOSEG_DONE, 0,
1010 		    0, &log, false);
1011 	}
1012 }
1013 
1014 
1015 static void
1016 rack_log_type_just_return(struct tcp_rack *rack, uint32_t cts, uint32_t tlen, uint32_t slot, uint8_t hpts_calling)
1017 {
1018 	if (rack->rc_tp->t_logstate != TCP_LOG_STATE_OFF) {
1019 		union tcp_log_stackspecific log;
1020 
1021 		memset(&log.u_bbr, 0, sizeof(log.u_bbr));
1022 		log.u_bbr.inhpts = rack->rc_inp->inp_in_hpts;
1023 		log.u_bbr.ininput = rack->rc_inp->inp_in_input;
1024 		log.u_bbr.flex1 = slot;
1025 		log.u_bbr.flex2 = rack->r_ctl.rc_hpts_flags;
1026 		log.u_bbr.flex7 = hpts_calling;
1027 		log.u_bbr.flex8 = rack->rc_in_persist;
1028 		TCP_LOG_EVENT(rack->rc_tp, NULL,
1029 		    &rack->rc_inp->inp_socket->so_rcv,
1030 		    &rack->rc_inp->inp_socket->so_snd,
1031 		    BBR_LOG_JUSTRET, 0,
1032 		    tlen, &log, false);
1033 	}
1034 }
1035 
1036 static void
1037 rack_log_to_cancel(struct tcp_rack *rack, int32_t hpts_removed, int line)
1038 {
1039 	if (rack->rc_tp->t_logstate != TCP_LOG_STATE_OFF) {
1040 		union tcp_log_stackspecific log;
1041 
1042 		memset(&log.u_bbr, 0, sizeof(log.u_bbr));
1043 		log.u_bbr.inhpts = rack->rc_inp->inp_in_hpts;
1044 		log.u_bbr.ininput = rack->rc_inp->inp_in_input;
1045 		log.u_bbr.flex1 = line;
1046 		log.u_bbr.flex2 = 0;
1047 		log.u_bbr.flex3 = rack->r_ctl.rc_hpts_flags;
1048 		log.u_bbr.flex4 = 0;
1049 		log.u_bbr.flex6 = rack->rc_tp->t_rxtcur;
1050 		log.u_bbr.flex8 = hpts_removed;
1051 		TCP_LOG_EVENT(rack->rc_tp, NULL,
1052 		    &rack->rc_inp->inp_socket->so_rcv,
1053 		    &rack->rc_inp->inp_socket->so_snd,
1054 		    BBR_LOG_TIMERCANC, 0,
1055 		    0, &log, false);
1056 	}
1057 }
1058 
1059 static void
1060 rack_log_to_processing(struct tcp_rack *rack, uint32_t cts, int32_t ret, int32_t timers)
1061 {
1062 	if (rack->rc_tp->t_logstate != TCP_LOG_STATE_OFF) {
1063 		union tcp_log_stackspecific log;
1064 
1065 		memset(&log.u_bbr, 0, sizeof(log.u_bbr));
1066 		log.u_bbr.flex1 = timers;
1067 		log.u_bbr.flex2 = ret;
1068 		log.u_bbr.flex3 = rack->r_ctl.rc_timer_exp;
1069 		log.u_bbr.flex4 = rack->r_ctl.rc_hpts_flags;
1070 		log.u_bbr.flex5 = cts;
1071 		TCP_LOG_EVENT(rack->rc_tp, NULL,
1072 		    &rack->rc_inp->inp_socket->so_rcv,
1073 		    &rack->rc_inp->inp_socket->so_snd,
1074 		    BBR_LOG_TO_PROCESS, 0,
1075 		    0, &log, false);
1076 	}
1077 }
1078 
1079 static void
1080 rack_counter_destroy()
1081 {
1082 	counter_u64_free(rack_badfr);
1083 	counter_u64_free(rack_badfr_bytes);
1084 	counter_u64_free(rack_rtm_prr_retran);
1085 	counter_u64_free(rack_rtm_prr_newdata);
1086 	counter_u64_free(rack_timestamp_mismatch);
1087 	counter_u64_free(rack_reorder_seen);
1088 	counter_u64_free(rack_tlp_tot);
1089 	counter_u64_free(rack_tlp_newdata);
1090 	counter_u64_free(rack_tlp_retran);
1091 	counter_u64_free(rack_tlp_retran_bytes);
1092 	counter_u64_free(rack_tlp_retran_fail);
1093 	counter_u64_free(rack_to_tot);
1094 	counter_u64_free(rack_to_arm_rack);
1095 	counter_u64_free(rack_to_arm_tlp);
1096 	counter_u64_free(rack_paced_segments);
1097 	counter_u64_free(rack_unpaced_segments);
1098 	counter_u64_free(rack_saw_enobuf);
1099 	counter_u64_free(rack_saw_enetunreach);
1100 	counter_u64_free(rack_to_alloc_hard);
1101 	counter_u64_free(rack_to_alloc_emerg);
1102 	counter_u64_free(rack_sack_proc_all);
1103 	counter_u64_free(rack_sack_proc_short);
1104 	counter_u64_free(rack_sack_proc_restart);
1105 	counter_u64_free(rack_to_alloc);
1106 	counter_u64_free(rack_find_high);
1107 	counter_u64_free(rack_runt_sacks);
1108 	counter_u64_free(rack_enter_tlp_calc);
1109 	counter_u64_free(rack_used_tlpmethod);
1110 	counter_u64_free(rack_used_tlpmethod2);
1111 	counter_u64_free(rack_progress_drops);
1112 	counter_u64_free(rack_input_idle_reduces);
1113 	counter_u64_free(rack_tlp_does_nada);
1114 	COUNTER_ARRAY_FREE(rack_out_size, TCP_MSS_ACCT_SIZE);
1115 	COUNTER_ARRAY_FREE(rack_opts_arry, RACK_OPTS_SIZE);
1116 }
1117 
1118 static struct rack_sendmap *
1119 rack_alloc(struct tcp_rack *rack)
1120 {
1121 	struct rack_sendmap *rsm;
1122 
1123 	counter_u64_add(rack_to_alloc, 1);
1124 	rack->r_ctl.rc_num_maps_alloced++;
1125 	rsm = uma_zalloc(rack_zone, M_NOWAIT);
1126 	if (rsm) {
1127 		return (rsm);
1128 	}
1129 	if (rack->rc_free_cnt) {
1130 		counter_u64_add(rack_to_alloc_emerg, 1);
1131 		rsm = TAILQ_FIRST(&rack->r_ctl.rc_free);
1132 		TAILQ_REMOVE(&rack->r_ctl.rc_free, rsm, r_next);
1133 		rack->rc_free_cnt--;
1134 		return (rsm);
1135 	}
1136 	return (NULL);
1137 }
1138 
1139 static void
1140 rack_free(struct tcp_rack *rack, struct rack_sendmap *rsm)
1141 {
1142 	rack->r_ctl.rc_num_maps_alloced--;
1143 	if (rack->r_ctl.rc_tlpsend == rsm)
1144 		rack->r_ctl.rc_tlpsend = NULL;
1145 	if (rack->r_ctl.rc_next == rsm)
1146 		rack->r_ctl.rc_next = NULL;
1147 	if (rack->r_ctl.rc_sacklast == rsm)
1148 		rack->r_ctl.rc_sacklast = NULL;
1149 	if (rack->rc_free_cnt < rack_free_cache) {
1150 		memset(rsm, 0, sizeof(struct rack_sendmap));
1151 		TAILQ_INSERT_TAIL(&rack->r_ctl.rc_free, rsm, r_next);
1152 		rack->rc_free_cnt++;
1153 		return;
1154 	}
1155 	uma_zfree(rack_zone, rsm);
1156 }
1157 
1158 /*
1159  * CC wrapper hook functions
1160  */
1161 static void
1162 rack_ack_received(struct tcpcb *tp, struct tcp_rack *rack, struct tcphdr *th, uint16_t nsegs,
1163     uint16_t type, int32_t recovery)
1164 {
1165 #ifdef NETFLIX_STATS
1166 	int32_t gput;
1167 #endif
1168 #ifdef NETFLIX_CWV
1169 	u_long old_cwnd = tp->snd_cwnd;
1170 #endif
1171 
1172 	INP_WLOCK_ASSERT(tp->t_inpcb);
1173 	tp->ccv->nsegs = nsegs;
1174 	tp->ccv->bytes_this_ack = BYTES_THIS_ACK(tp, th);
1175 	if ((recovery) && (rack->r_ctl.rc_early_recovery_segs)) {
1176 		uint32_t max;
1177 
1178 		max = rack->r_ctl.rc_early_recovery_segs * tp->t_maxseg;
1179 		if (tp->ccv->bytes_this_ack > max) {
1180 			tp->ccv->bytes_this_ack = max;
1181 		}
1182 	}
1183 	if (tp->snd_cwnd <= tp->snd_wnd)
1184 		tp->ccv->flags |= CCF_CWND_LIMITED;
1185 	else
1186 		tp->ccv->flags &= ~CCF_CWND_LIMITED;
1187 
1188 	if (type == CC_ACK) {
1189 #ifdef NETFLIX_STATS
1190 		stats_voi_update_abs_s32(tp->t_stats, VOI_TCP_CALCFRWINDIFF,
1191 		    ((int32_t) tp->snd_cwnd) - tp->snd_wnd);
1192 		if ((tp->t_flags & TF_GPUTINPROG) &&
1193 		    SEQ_GEQ(th->th_ack, tp->gput_ack)) {
1194 			gput = (((int64_t) (th->th_ack - tp->gput_seq)) << 3) /
1195 			    max(1, tcp_ts_getticks() - tp->gput_ts);
1196 			stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_GPUT,
1197 			    gput);
1198 			/*
1199 			 * XXXLAS: This is a temporary hack, and should be
1200 			 * chained off VOI_TCP_GPUT when stats(9) grows an
1201 			 * API to deal with chained VOIs.
1202 			 */
1203 			if (tp->t_stats_gput_prev > 0)
1204 				stats_voi_update_abs_s32(tp->t_stats,
1205 				    VOI_TCP_GPUT_ND,
1206 				    ((gput - tp->t_stats_gput_prev) * 100) /
1207 				    tp->t_stats_gput_prev);
1208 			tp->t_flags &= ~TF_GPUTINPROG;
1209 			tp->t_stats_gput_prev = gput;
1210 #ifdef NETFLIX_CWV
1211 			if (tp->t_maxpeakrate) {
1212 				/*
1213 				 * We update t_peakrate_thr. This gives us roughly
1214 				 * one update per round trip time.
1215 				 */
1216 				tcp_update_peakrate_thr(tp);
1217 			}
1218 #endif
1219 		}
1220 #endif
1221 		if (tp->snd_cwnd > tp->snd_ssthresh) {
1222 			tp->t_bytes_acked += min(tp->ccv->bytes_this_ack,
1223 			    nsegs * V_tcp_abc_l_var * tp->t_maxseg);
1224 			if (tp->t_bytes_acked >= tp->snd_cwnd) {
1225 				tp->t_bytes_acked -= tp->snd_cwnd;
1226 				tp->ccv->flags |= CCF_ABC_SENTAWND;
1227 			}
1228 		} else {
1229 			tp->ccv->flags &= ~CCF_ABC_SENTAWND;
1230 			tp->t_bytes_acked = 0;
1231 		}
1232 	}
1233 	if (CC_ALGO(tp)->ack_received != NULL) {
1234 		/* XXXLAS: Find a way to live without this */
1235 		tp->ccv->curack = th->th_ack;
1236 		CC_ALGO(tp)->ack_received(tp->ccv, type);
1237 	}
1238 #ifdef NETFLIX_STATS
1239 	stats_voi_update_abs_ulong(tp->t_stats, VOI_TCP_LCWIN, tp->snd_cwnd);
1240 #endif
1241 	if (rack->r_ctl.rc_rack_largest_cwnd < tp->snd_cwnd) {
1242 		rack->r_ctl.rc_rack_largest_cwnd = tp->snd_cwnd;
1243 	}
1244 #ifdef NETFLIX_CWV
1245 	if (tp->cwv_enabled) {
1246 		/*
1247 		 * Per RFC 7661: The behaviour in the non-validated phase is
1248 		 * specified as: o  A sender determines whether to increase
1249 		 * the cwnd based upon whether it is cwnd-limited (see
1250 		 * Section 4.5.3): * A sender that is cwnd-limited MAY use
1251 		 * the standard TCP method to increase cwnd (i.e., the
1252 		 * standard method permits a TCP sender that fully utilises
1253 		 * the cwnd to increase the cwnd each time it receives an
1254 		 * ACK). * A sender that is not cwnd-limited MUST NOT
1255 		 * increase the cwnd when ACK packets are received in this
1256 		 * phase (i.e., needs to avoid growing the cwnd when it has
1257 		 * not recently sent using the current size of cwnd).
1258 		 */
1259 		if ((tp->snd_cwnd > old_cwnd) &&
1260 		    (tp->cwv_cwnd_valid == 0) &&
1261 		    (!(tp->ccv->flags & CCF_CWND_LIMITED))) {
1262 			tp->snd_cwnd = old_cwnd;
1263 		}
1264 		/* Try to update pipeAck and NCWV state */
1265 		if (TCPS_HAVEESTABLISHED(tp->t_state) &&
1266 		    !IN_RECOVERY(tp->t_flags)) {
1267 			uint32_t data = sbavail(&(tp->t_inpcb->inp_socket->so_snd));
1268 
1269 			tcp_newcwv_update_pipeack(tp, data);
1270 		}
1271 	}
1272 	/* we enforce max peak rate if it is set. */
1273 	if (tp->t_peakrate_thr && tp->snd_cwnd > tp->t_peakrate_thr) {
1274 		tp->snd_cwnd = tp->t_peakrate_thr;
1275 	}
1276 #endif
1277 }
1278 
1279 static void
1280 tcp_rack_partialack(struct tcpcb *tp, struct tcphdr *th)
1281 {
1282 	struct tcp_rack *rack;
1283 
1284 	rack = (struct tcp_rack *)tp->t_fb_ptr;
1285 	INP_WLOCK_ASSERT(tp->t_inpcb);
1286 	if (rack->r_ctl.rc_prr_sndcnt > 0)
1287 		rack->r_wanted_output++;
1288 }
1289 
1290 static void
1291 rack_post_recovery(struct tcpcb *tp, struct tcphdr *th)
1292 {
1293 	struct tcp_rack *rack;
1294 
1295 	INP_WLOCK_ASSERT(tp->t_inpcb);
1296 	rack = (struct tcp_rack *)tp->t_fb_ptr;
1297 	if (CC_ALGO(tp)->post_recovery != NULL) {
1298 		tp->ccv->curack = th->th_ack;
1299 		CC_ALGO(tp)->post_recovery(tp->ccv);
1300 	}
1301 	/*
1302 	 * Here we can in theory adjust cwnd to be based on the number of
1303 	 * losses in the window (rack->r_ctl.rc_loss_count). This is done
1304 	 * based on the rack_use_proportional flag.
1305 	 */
1306 	if (rack->r_ctl.rc_prop_reduce && rack->r_ctl.rc_prop_rate) {
1307 		int32_t reduce;
1308 
1309 		reduce = (rack->r_ctl.rc_loss_count * rack->r_ctl.rc_prop_rate);
1310 		if (reduce > 50) {
1311 			reduce = 50;
1312 		}
1313 		tp->snd_cwnd -= ((reduce * tp->snd_cwnd) / 100);
1314 	} else {
1315 		if (tp->snd_cwnd > tp->snd_ssthresh) {
1316 			/* Drop us down to the ssthresh (1/2 cwnd at loss) */
1317 			tp->snd_cwnd = tp->snd_ssthresh;
1318 		}
1319 	}
1320 	if (rack->r_ctl.rc_prr_sndcnt > 0) {
1321 		/* Suck the next prr cnt back into cwnd */
1322 		tp->snd_cwnd += rack->r_ctl.rc_prr_sndcnt;
1323 		rack->r_ctl.rc_prr_sndcnt = 0;
1324 	}
1325 	EXIT_RECOVERY(tp->t_flags);
1326 
1327 
1328 #ifdef NETFLIX_CWV
1329 	if (tp->cwv_enabled) {
1330 		if ((tp->cwv_cwnd_valid == 0) &&
1331 		    (tp->snd_cwv.in_recovery))
1332 			tcp_newcwv_end_recovery(tp);
1333 	}
1334 #endif
1335 }
1336 
1337 static void
1338 rack_cong_signal(struct tcpcb *tp, struct tcphdr *th, uint32_t type)
1339 {
1340 	struct tcp_rack *rack;
1341 
1342 	INP_WLOCK_ASSERT(tp->t_inpcb);
1343 
1344 	rack = (struct tcp_rack *)tp->t_fb_ptr;
1345 	switch (type) {
1346 	case CC_NDUPACK:
1347 /*		rack->r_ctl.rc_ssthresh_set = 1;*/
1348 		if (!IN_FASTRECOVERY(tp->t_flags)) {
1349 			rack->r_ctl.rc_tlp_rtx_out = 0;
1350 			rack->r_ctl.rc_prr_delivered = 0;
1351 			rack->r_ctl.rc_prr_out = 0;
1352 			rack->r_ctl.rc_loss_count = 0;
1353 			rack->r_ctl.rc_prr_sndcnt = tp->t_maxseg;
1354 			rack->r_ctl.rc_prr_recovery_fs = tp->snd_max - tp->snd_una;
1355 			tp->snd_recover = tp->snd_max;
1356 			if (tp->t_flags & TF_ECN_PERMIT)
1357 				tp->t_flags |= TF_ECN_SND_CWR;
1358 		}
1359 		break;
1360 	case CC_ECN:
1361 		if (!IN_CONGRECOVERY(tp->t_flags)) {
1362 			TCPSTAT_INC(tcps_ecn_rcwnd);
1363 			tp->snd_recover = tp->snd_max;
1364 			if (tp->t_flags & TF_ECN_PERMIT)
1365 				tp->t_flags |= TF_ECN_SND_CWR;
1366 		}
1367 		break;
1368 	case CC_RTO:
1369 		tp->t_dupacks = 0;
1370 		tp->t_bytes_acked = 0;
1371 		EXIT_RECOVERY(tp->t_flags);
1372 		tp->snd_ssthresh = max(2, min(tp->snd_wnd, tp->snd_cwnd) / 2 /
1373 		    tp->t_maxseg) * tp->t_maxseg;
1374 		tp->snd_cwnd = tp->t_maxseg;
1375 		break;
1376 	case CC_RTO_ERR:
1377 		TCPSTAT_INC(tcps_sndrexmitbad);
1378 		/* RTO was unnecessary, so reset everything. */
1379 		tp->snd_cwnd = tp->snd_cwnd_prev;
1380 		tp->snd_ssthresh = tp->snd_ssthresh_prev;
1381 		tp->snd_recover = tp->snd_recover_prev;
1382 		if (tp->t_flags & TF_WASFRECOVERY)
1383 			ENTER_FASTRECOVERY(tp->t_flags);
1384 		if (tp->t_flags & TF_WASCRECOVERY)
1385 			ENTER_CONGRECOVERY(tp->t_flags);
1386 		tp->snd_nxt = tp->snd_max;
1387 		tp->t_badrxtwin = 0;
1388 		break;
1389 	}
1390 
1391 	if (CC_ALGO(tp)->cong_signal != NULL) {
1392 		if (th != NULL)
1393 			tp->ccv->curack = th->th_ack;
1394 		CC_ALGO(tp)->cong_signal(tp->ccv, type);
1395 	}
1396 #ifdef NETFLIX_CWV
1397 	if (tp->cwv_enabled) {
1398 		if (tp->snd_cwv.in_recovery == 0 && IN_RECOVERY(tp->t_flags)) {
1399 			tcp_newcwv_enter_recovery(tp);
1400 		}
1401 		if (type == CC_RTO) {
1402 			tcp_newcwv_reset(tp);
1403 		}
1404 	}
1405 #endif
1406 }
1407 
1408 
1409 
1410 static inline void
1411 rack_cc_after_idle(struct tcpcb *tp, int reduce_largest)
1412 {
1413 	uint32_t i_cwnd;
1414 
1415 	INP_WLOCK_ASSERT(tp->t_inpcb);
1416 
1417 #ifdef NETFLIX_STATS
1418 	TCPSTAT_INC(tcps_idle_restarts);
1419 	if (tp->t_state == TCPS_ESTABLISHED)
1420 		TCPSTAT_INC(tcps_idle_estrestarts);
1421 #endif
1422 	if (CC_ALGO(tp)->after_idle != NULL)
1423 		CC_ALGO(tp)->after_idle(tp->ccv);
1424 
1425 	if (tp->snd_cwnd == 1)
1426 		i_cwnd = tp->t_maxseg;		/* SYN(-ACK) lost */
1427 	else
1428 		i_cwnd = tcp_compute_initwnd(tcp_maxseg(tp));
1429 
1430 	if (reduce_largest) {
1431 		/*
1432 		 * Do we reduce the largest cwnd to make
1433 		 * rack play nice on restart hptsi wise?
1434 		 */
1435 		if (((struct tcp_rack *)tp->t_fb_ptr)->r_ctl.rc_rack_largest_cwnd  > i_cwnd)
1436 			((struct tcp_rack *)tp->t_fb_ptr)->r_ctl.rc_rack_largest_cwnd = i_cwnd;
1437 	}
1438 	/*
1439 	 * Being idle is no differnt than the initial window. If the cc
1440 	 * clamps it down below the initial window raise it to the initial
1441 	 * window.
1442 	 */
1443 	if (tp->snd_cwnd < i_cwnd) {
1444 		tp->snd_cwnd = i_cwnd;
1445 	}
1446 }
1447 
1448 
1449 /*
1450  * Indicate whether this ack should be delayed.  We can delay the ack if
1451  * following conditions are met:
1452  *	- There is no delayed ack timer in progress.
1453  *	- Our last ack wasn't a 0-sized window. We never want to delay
1454  *	  the ack that opens up a 0-sized window.
1455  *	- LRO wasn't used for this segment. We make sure by checking that the
1456  *	  segment size is not larger than the MSS.
1457  *	- Delayed acks are enabled or this is a half-synchronized T/TCP
1458  *	  connection.
1459  */
1460 #define DELAY_ACK(tp, tlen)			 \
1461 	(((tp->t_flags & TF_RXWIN0SENT) == 0) && \
1462 	((tp->t_flags & TF_DELACK) == 0) && 	 \
1463 	(tlen <= tp->t_maxseg) &&		 \
1464 	(tp->t_delayed_ack || (tp->t_flags & TF_NEEDSYN)))
1465 
1466 static inline void
1467 rack_calc_rwin(struct socket *so, struct tcpcb *tp)
1468 {
1469 	int32_t win;
1470 
1471 	/*
1472 	 * Calculate amount of space in receive window, and then do TCP
1473 	 * input processing. Receive window is amount of space in rcv queue,
1474 	 * but not less than advertised window.
1475 	 */
1476 	win = sbspace(&so->so_rcv);
1477 	if (win < 0)
1478 		win = 0;
1479 	tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt));
1480 }
1481 
1482 static void
1483 rack_do_drop(struct mbuf *m, struct tcpcb *tp)
1484 {
1485 	/*
1486 	 * Drop space held by incoming segment and return.
1487 	 */
1488 	if (tp != NULL)
1489 		INP_WUNLOCK(tp->t_inpcb);
1490 	if (m)
1491 		m_freem(m);
1492 }
1493 
1494 static void
1495 rack_do_dropwithreset(struct mbuf *m, struct tcpcb *tp, struct tcphdr *th,
1496     int32_t rstreason, int32_t tlen)
1497 {
1498 	if (tp != NULL) {
1499 		tcp_dropwithreset(m, th, tp, tlen, rstreason);
1500 		INP_WUNLOCK(tp->t_inpcb);
1501 	} else
1502 		tcp_dropwithreset(m, th, NULL, tlen, rstreason);
1503 }
1504 
1505 /*
1506  * The value in ret_val informs the caller
1507  * if we dropped the tcb (and lock) or not.
1508  * 1 = we dropped it, 0 = the TCB is still locked
1509  * and valid.
1510  */
1511 static void
1512 rack_do_dropafterack(struct mbuf *m, struct tcpcb *tp, struct tcphdr *th, int32_t thflags, int32_t tlen, int32_t * ret_val)
1513 {
1514 	/*
1515 	 * Generate an ACK dropping incoming segment if it occupies sequence
1516 	 * space, where the ACK reflects our state.
1517 	 *
1518 	 * We can now skip the test for the RST flag since all paths to this
1519 	 * code happen after packets containing RST have been dropped.
1520 	 *
1521 	 * In the SYN-RECEIVED state, don't send an ACK unless the segment
1522 	 * we received passes the SYN-RECEIVED ACK test. If it fails send a
1523 	 * RST.  This breaks the loop in the "LAND" DoS attack, and also
1524 	 * prevents an ACK storm between two listening ports that have been
1525 	 * sent forged SYN segments, each with the source address of the
1526 	 * other.
1527 	 */
1528 	struct tcp_rack *rack;
1529 
1530 	if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) &&
1531 	    (SEQ_GT(tp->snd_una, th->th_ack) ||
1532 	    SEQ_GT(th->th_ack, tp->snd_max))) {
1533 		*ret_val = 1;
1534 		rack_do_dropwithreset(m, tp, th, BANDLIM_RST_OPENPORT, tlen);
1535 		return;
1536 	} else
1537 		*ret_val = 0;
1538 	rack = (struct tcp_rack *)tp->t_fb_ptr;
1539 	rack->r_wanted_output++;
1540 	tp->t_flags |= TF_ACKNOW;
1541 	if (m)
1542 		m_freem(m);
1543 }
1544 
1545 
1546 static int
1547 rack_process_rst(struct mbuf *m, struct tcphdr *th, struct socket *so, struct tcpcb *tp)
1548 {
1549 	/*
1550 	 * RFC5961 Section 3.2
1551 	 *
1552 	 * - RST drops connection only if SEG.SEQ == RCV.NXT. - If RST is in
1553 	 * window, we send challenge ACK.
1554 	 *
1555 	 * Note: to take into account delayed ACKs, we should test against
1556 	 * last_ack_sent instead of rcv_nxt. Note 2: we handle special case
1557 	 * of closed window, not covered by the RFC.
1558 	 */
1559 	int dropped = 0;
1560 
1561 	if ((SEQ_GEQ(th->th_seq, (tp->last_ack_sent - 1)) &&
1562 	    SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) ||
1563 	    (tp->rcv_wnd == 0 && tp->last_ack_sent == th->th_seq)) {
1564 
1565 		INP_INFO_RLOCK_ASSERT(&V_tcbinfo);
1566 		KASSERT(tp->t_state != TCPS_SYN_SENT,
1567 		    ("%s: TH_RST for TCPS_SYN_SENT th %p tp %p",
1568 		    __func__, th, tp));
1569 
1570 		if (V_tcp_insecure_rst ||
1571 		    (tp->last_ack_sent == th->th_seq) ||
1572 		    (tp->rcv_nxt == th->th_seq) ||
1573 		    ((tp->last_ack_sent - 1) == th->th_seq)) {
1574 			TCPSTAT_INC(tcps_drops);
1575 			/* Drop the connection. */
1576 			switch (tp->t_state) {
1577 			case TCPS_SYN_RECEIVED:
1578 				so->so_error = ECONNREFUSED;
1579 				goto close;
1580 			case TCPS_ESTABLISHED:
1581 			case TCPS_FIN_WAIT_1:
1582 			case TCPS_FIN_WAIT_2:
1583 			case TCPS_CLOSE_WAIT:
1584 			case TCPS_CLOSING:
1585 			case TCPS_LAST_ACK:
1586 				so->so_error = ECONNRESET;
1587 		close:
1588 				tcp_state_change(tp, TCPS_CLOSED);
1589 				/* FALLTHROUGH */
1590 			default:
1591 				tp = tcp_close(tp);
1592 			}
1593 			dropped = 1;
1594 			rack_do_drop(m, tp);
1595 		} else {
1596 			TCPSTAT_INC(tcps_badrst);
1597 			/* Send challenge ACK. */
1598 			tcp_respond(tp, mtod(m, void *), th, m,
1599 			    tp->rcv_nxt, tp->snd_nxt, TH_ACK);
1600 			tp->last_ack_sent = tp->rcv_nxt;
1601 		}
1602 	} else {
1603 		m_freem(m);
1604 	}
1605 	return (dropped);
1606 }
1607 
1608 /*
1609  * The value in ret_val informs the caller
1610  * if we dropped the tcb (and lock) or not.
1611  * 1 = we dropped it, 0 = the TCB is still locked
1612  * and valid.
1613  */
1614 static void
1615 rack_challenge_ack(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, int32_t * ret_val)
1616 {
1617 	INP_INFO_RLOCK_ASSERT(&V_tcbinfo);
1618 
1619 	TCPSTAT_INC(tcps_badsyn);
1620 	if (V_tcp_insecure_syn &&
1621 	    SEQ_GEQ(th->th_seq, tp->last_ack_sent) &&
1622 	    SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) {
1623 		tp = tcp_drop(tp, ECONNRESET);
1624 		*ret_val = 1;
1625 		rack_do_drop(m, tp);
1626 	} else {
1627 		/* Send challenge ACK. */
1628 		tcp_respond(tp, mtod(m, void *), th, m, tp->rcv_nxt,
1629 		    tp->snd_nxt, TH_ACK);
1630 		tp->last_ack_sent = tp->rcv_nxt;
1631 		m = NULL;
1632 		*ret_val = 0;
1633 		rack_do_drop(m, NULL);
1634 	}
1635 }
1636 
1637 /*
1638  * rack_ts_check returns 1 for you should not proceed. It places
1639  * in ret_val what should be returned 1/0 by the caller. The 1 indicates
1640  * that the TCB is unlocked and probably dropped. The 0 indicates the
1641  * TCB is still valid and locked.
1642  */
1643 static int
1644 rack_ts_check(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, int32_t tlen, int32_t thflags, int32_t * ret_val)
1645 {
1646 
1647 	/* Check to see if ts_recent is over 24 days old.  */
1648 	if (tcp_ts_getticks() - tp->ts_recent_age > TCP_PAWS_IDLE) {
1649 		/*
1650 		 * Invalidate ts_recent.  If this segment updates ts_recent,
1651 		 * the age will be reset later and ts_recent will get a
1652 		 * valid value.  If it does not, setting ts_recent to zero
1653 		 * will at least satisfy the requirement that zero be placed
1654 		 * in the timestamp echo reply when ts_recent isn't valid.
1655 		 * The age isn't reset until we get a valid ts_recent
1656 		 * because we don't want out-of-order segments to be dropped
1657 		 * when ts_recent is old.
1658 		 */
1659 		tp->ts_recent = 0;
1660 	} else {
1661 		TCPSTAT_INC(tcps_rcvduppack);
1662 		TCPSTAT_ADD(tcps_rcvdupbyte, tlen);
1663 		TCPSTAT_INC(tcps_pawsdrop);
1664 		*ret_val = 0;
1665 		if (tlen) {
1666 			rack_do_dropafterack(m, tp, th, thflags, tlen, ret_val);
1667 		} else {
1668 			rack_do_drop(m, NULL);
1669 		}
1670 		return (1);
1671 	}
1672 	return (0);
1673 }
1674 
1675 /*
1676  * rack_drop_checks returns 1 for you should not proceed. It places
1677  * in ret_val what should be returned 1/0 by the caller. The 1 indicates
1678  * that the TCB is unlocked and probably dropped. The 0 indicates the
1679  * TCB is still valid and locked.
1680  */
1681 static int
1682 rack_drop_checks(struct tcpopt *to, struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, int32_t * tlenp,  int32_t * thf, int32_t * drop_hdrlen, int32_t * ret_val)
1683 {
1684 	int32_t todrop;
1685 	int32_t thflags;
1686 	int32_t tlen;
1687 
1688 	thflags = *thf;
1689 	tlen = *tlenp;
1690 	todrop = tp->rcv_nxt - th->th_seq;
1691 	if (todrop > 0) {
1692 		if (thflags & TH_SYN) {
1693 			thflags &= ~TH_SYN;
1694 			th->th_seq++;
1695 			if (th->th_urp > 1)
1696 				th->th_urp--;
1697 			else
1698 				thflags &= ~TH_URG;
1699 			todrop--;
1700 		}
1701 		/*
1702 		 * Following if statement from Stevens, vol. 2, p. 960.
1703 		 */
1704 		if (todrop > tlen
1705 		    || (todrop == tlen && (thflags & TH_FIN) == 0)) {
1706 			/*
1707 			 * Any valid FIN must be to the left of the window.
1708 			 * At this point the FIN must be a duplicate or out
1709 			 * of sequence; drop it.
1710 			 */
1711 			thflags &= ~TH_FIN;
1712 			/*
1713 			 * Send an ACK to resynchronize and drop any data.
1714 			 * But keep on processing for RST or ACK.
1715 			 */
1716 			tp->t_flags |= TF_ACKNOW;
1717 			todrop = tlen;
1718 			TCPSTAT_INC(tcps_rcvduppack);
1719 			TCPSTAT_ADD(tcps_rcvdupbyte, todrop);
1720 		} else {
1721 			TCPSTAT_INC(tcps_rcvpartduppack);
1722 			TCPSTAT_ADD(tcps_rcvpartdupbyte, todrop);
1723 		}
1724 		*drop_hdrlen += todrop;	/* drop from the top afterwards */
1725 		th->th_seq += todrop;
1726 		tlen -= todrop;
1727 		if (th->th_urp > todrop)
1728 			th->th_urp -= todrop;
1729 		else {
1730 			thflags &= ~TH_URG;
1731 			th->th_urp = 0;
1732 		}
1733 	}
1734 	/*
1735 	 * If segment ends after window, drop trailing data (and PUSH and
1736 	 * FIN); if nothing left, just ACK.
1737 	 */
1738 	todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd);
1739 	if (todrop > 0) {
1740 		TCPSTAT_INC(tcps_rcvpackafterwin);
1741 		if (todrop >= tlen) {
1742 			TCPSTAT_ADD(tcps_rcvbyteafterwin, tlen);
1743 			/*
1744 			 * If window is closed can only take segments at
1745 			 * window edge, and have to drop data and PUSH from
1746 			 * incoming segments.  Continue processing, but
1747 			 * remember to ack.  Otherwise, drop segment and
1748 			 * ack.
1749 			 */
1750 			if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) {
1751 				tp->t_flags |= TF_ACKNOW;
1752 				TCPSTAT_INC(tcps_rcvwinprobe);
1753 			} else {
1754 				rack_do_dropafterack(m, tp, th, thflags, tlen, ret_val);
1755 				return (1);
1756 			}
1757 		} else
1758 			TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop);
1759 		m_adj(m, -todrop);
1760 		tlen -= todrop;
1761 		thflags &= ~(TH_PUSH | TH_FIN);
1762 	}
1763 	*thf = thflags;
1764 	*tlenp = tlen;
1765 	return (0);
1766 }
1767 
1768 static struct rack_sendmap *
1769 rack_find_lowest_rsm(struct tcp_rack *rack)
1770 {
1771 	struct rack_sendmap *rsm;
1772 
1773 	/*
1774 	 * Walk the time-order transmitted list looking for an rsm that is
1775 	 * not acked. This will be the one that was sent the longest time
1776 	 * ago that is still outstanding.
1777 	 */
1778 	TAILQ_FOREACH(rsm, &rack->r_ctl.rc_tmap, r_tnext) {
1779 		if (rsm->r_flags & RACK_ACKED) {
1780 			continue;
1781 		}
1782 		goto finish;
1783 	}
1784 finish:
1785 	return (rsm);
1786 }
1787 
1788 static struct rack_sendmap *
1789 rack_find_high_nonack(struct tcp_rack *rack, struct rack_sendmap *rsm)
1790 {
1791 	struct rack_sendmap *prsm;
1792 
1793 	/*
1794 	 * Walk the sequence order list backward until we hit and arrive at
1795 	 * the highest seq not acked. In theory when this is called it
1796 	 * should be the last segment (which it was not).
1797 	 */
1798 	counter_u64_add(rack_find_high, 1);
1799 	prsm = rsm;
1800 	TAILQ_FOREACH_REVERSE_FROM(prsm, &rack->r_ctl.rc_map, rack_head, r_next) {
1801 		if (prsm->r_flags & (RACK_ACKED | RACK_HAS_FIN)) {
1802 			continue;
1803 		}
1804 		return (prsm);
1805 	}
1806 	return (NULL);
1807 }
1808 
1809 
1810 static uint32_t
1811 rack_calc_thresh_rack(struct tcp_rack *rack, uint32_t srtt, uint32_t cts)
1812 {
1813 	int32_t lro;
1814 	uint32_t thresh;
1815 
1816 	/*
1817 	 * lro is the flag we use to determine if we have seen reordering.
1818 	 * If it gets set we have seen reordering. The reorder logic either
1819 	 * works in one of two ways:
1820 	 *
1821 	 * If reorder-fade is configured, then we track the last time we saw
1822 	 * re-ordering occur. If we reach the point where enough time as
1823 	 * passed we no longer consider reordering has occuring.
1824 	 *
1825 	 * Or if reorder-face is 0, then once we see reordering we consider
1826 	 * the connection to alway be subject to reordering and just set lro
1827 	 * to 1.
1828 	 *
1829 	 * In the end if lro is non-zero we add the extra time for
1830 	 * reordering in.
1831 	 */
1832 	if (srtt == 0)
1833 		srtt = 1;
1834 	if (rack->r_ctl.rc_reorder_ts) {
1835 		if (rack->r_ctl.rc_reorder_fade) {
1836 			if (SEQ_GEQ(cts, rack->r_ctl.rc_reorder_ts)) {
1837 				lro = cts - rack->r_ctl.rc_reorder_ts;
1838 				if (lro == 0) {
1839 					/*
1840 					 * No time as passed since the last
1841 					 * reorder, mark it as reordering.
1842 					 */
1843 					lro = 1;
1844 				}
1845 			} else {
1846 				/* Negative time? */
1847 				lro = 0;
1848 			}
1849 			if (lro > rack->r_ctl.rc_reorder_fade) {
1850 				/* Turn off reordering seen too */
1851 				rack->r_ctl.rc_reorder_ts = 0;
1852 				lro = 0;
1853 			}
1854 		} else {
1855 			/* Reodering does not fade */
1856 			lro = 1;
1857 		}
1858 	} else {
1859 		lro = 0;
1860 	}
1861 	thresh = srtt + rack->r_ctl.rc_pkt_delay;
1862 	if (lro) {
1863 		/* It must be set, if not you get 1/4 rtt */
1864 		if (rack->r_ctl.rc_reorder_shift)
1865 			thresh += (srtt >> rack->r_ctl.rc_reorder_shift);
1866 		else
1867 			thresh += (srtt >> 2);
1868 	} else {
1869 		thresh += 1;
1870 	}
1871 	/* We don't let the rack timeout be above a RTO */
1872 
1873 	if (thresh > TICKS_2_MSEC(rack->rc_tp->t_rxtcur)) {
1874 		thresh = TICKS_2_MSEC(rack->rc_tp->t_rxtcur);
1875 	}
1876 	/* And we don't want it above the RTO max either */
1877 	if (thresh > rack_rto_max) {
1878 		thresh = rack_rto_max;
1879 	}
1880 	return (thresh);
1881 }
1882 
1883 static uint32_t
1884 rack_calc_thresh_tlp(struct tcpcb *tp, struct tcp_rack *rack,
1885 		     struct rack_sendmap *rsm, uint32_t srtt)
1886 {
1887 	struct rack_sendmap *prsm;
1888 	uint32_t thresh, len;
1889 	int maxseg;
1890 
1891 	if (srtt == 0)
1892 		srtt = 1;
1893 	if (rack->r_ctl.rc_tlp_threshold)
1894 		thresh = srtt + (srtt / rack->r_ctl.rc_tlp_threshold);
1895 	else
1896 		thresh = (srtt * 2);
1897 
1898 	/* Get the previous sent packet, if any  */
1899 	maxseg = tcp_maxseg(tp);
1900 	counter_u64_add(rack_enter_tlp_calc, 1);
1901 	len = rsm->r_end - rsm->r_start;
1902 	if (rack->rack_tlp_threshold_use == TLP_USE_ID) {
1903 		/* Exactly like the ID */
1904 		if (((tp->snd_max - tp->snd_una) - rack->r_ctl.rc_sacked + rack->r_ctl.rc_holes_rxt) <= maxseg) {
1905 			uint32_t alt_thresh;
1906 			/*
1907 			 * Compensate for delayed-ack with the d-ack time.
1908 			 */
1909 			counter_u64_add(rack_used_tlpmethod, 1);
1910 			alt_thresh = srtt + (srtt / 2) + rack_delayed_ack_time;
1911 			if (alt_thresh > thresh)
1912 				thresh = alt_thresh;
1913 		}
1914 	} else if (rack->rack_tlp_threshold_use == TLP_USE_TWO_ONE) {
1915 		/* 2.1 behavior */
1916 		prsm = TAILQ_PREV(rsm, rack_head, r_tnext);
1917 		if (prsm && (len <= maxseg)) {
1918 			/*
1919 			 * Two packets outstanding, thresh should be (2*srtt) +
1920 			 * possible inter-packet delay (if any).
1921 			 */
1922 			uint32_t inter_gap = 0;
1923 			int idx, nidx;
1924 
1925 			counter_u64_add(rack_used_tlpmethod, 1);
1926 			idx = rsm->r_rtr_cnt - 1;
1927 			nidx = prsm->r_rtr_cnt - 1;
1928 			if (TSTMP_GEQ(rsm->r_tim_lastsent[nidx], prsm->r_tim_lastsent[idx])) {
1929 				/* Yes it was sent later (or at the same time) */
1930 				inter_gap = rsm->r_tim_lastsent[idx] - prsm->r_tim_lastsent[nidx];
1931 			}
1932 			thresh += inter_gap;
1933 		} else 	if (len <= maxseg) {
1934 			/*
1935 			 * Possibly compensate for delayed-ack.
1936 			 */
1937 			uint32_t alt_thresh;
1938 
1939 			counter_u64_add(rack_used_tlpmethod2, 1);
1940 			alt_thresh = srtt + (srtt / 2) + rack_delayed_ack_time;
1941 			if (alt_thresh > thresh)
1942 				thresh = alt_thresh;
1943 		}
1944 	} else if (rack->rack_tlp_threshold_use == TLP_USE_TWO_TWO) {
1945 		/* 2.2 behavior */
1946 		if (len <= maxseg) {
1947 			uint32_t alt_thresh;
1948 			/*
1949 			 * Compensate for delayed-ack with the d-ack time.
1950 			 */
1951 			counter_u64_add(rack_used_tlpmethod, 1);
1952 			alt_thresh = srtt + (srtt / 2) + rack_delayed_ack_time;
1953 			if (alt_thresh > thresh)
1954 				thresh = alt_thresh;
1955 		}
1956 	}
1957  	/* Not above an RTO */
1958 	if (thresh > TICKS_2_MSEC(tp->t_rxtcur)) {
1959 		thresh = TICKS_2_MSEC(tp->t_rxtcur);
1960 	}
1961 	/* Not above a RTO max */
1962 	if (thresh > rack_rto_max) {
1963 		thresh = rack_rto_max;
1964 	}
1965 	/* Apply user supplied min TLP */
1966 	if (thresh < rack_tlp_min) {
1967 		thresh = rack_tlp_min;
1968 	}
1969 	return (thresh);
1970 }
1971 
1972 static struct rack_sendmap *
1973 rack_check_recovery_mode(struct tcpcb *tp, uint32_t tsused)
1974 {
1975 	/*
1976 	 * Check to see that we don't need to fall into recovery. We will
1977 	 * need to do so if our oldest transmit is past the time we should
1978 	 * have had an ack.
1979 	 */
1980 	struct tcp_rack *rack;
1981 	struct rack_sendmap *rsm;
1982 	int32_t idx;
1983 	uint32_t srtt_cur, srtt, thresh;
1984 
1985 	rack = (struct tcp_rack *)tp->t_fb_ptr;
1986 	if (TAILQ_EMPTY(&rack->r_ctl.rc_map)) {
1987 		return (NULL);
1988 	}
1989 	srtt_cur = tp->t_srtt >> TCP_RTT_SHIFT;
1990 	srtt = TICKS_2_MSEC(srtt_cur);
1991 	if (rack->rc_rack_rtt && (srtt > rack->rc_rack_rtt))
1992 		srtt = rack->rc_rack_rtt;
1993 
1994 	rsm = TAILQ_FIRST(&rack->r_ctl.rc_tmap);
1995 	if (rsm == NULL)
1996 		return (NULL);
1997 
1998 	if (rsm->r_flags & RACK_ACKED) {
1999 		rsm = rack_find_lowest_rsm(rack);
2000 		if (rsm == NULL)
2001 			return (NULL);
2002 	}
2003 	idx = rsm->r_rtr_cnt - 1;
2004 	thresh = rack_calc_thresh_rack(rack, srtt, tsused);
2005 	if (tsused < rsm->r_tim_lastsent[idx]) {
2006 		return (NULL);
2007 	}
2008 	if ((tsused - rsm->r_tim_lastsent[idx]) < thresh) {
2009 		return (NULL);
2010 	}
2011 	/* Ok if we reach here we are over-due */
2012 	rack->r_ctl.rc_rsm_start = rsm->r_start;
2013 	rack->r_ctl.rc_cwnd_at = tp->snd_cwnd;
2014 	rack->r_ctl.rc_ssthresh_at = tp->snd_ssthresh;
2015 	rack_cong_signal(tp, NULL, CC_NDUPACK);
2016 	return (rsm);
2017 }
2018 
2019 static uint32_t
2020 rack_get_persists_timer_val(struct tcpcb *tp, struct tcp_rack *rack)
2021 {
2022 	int32_t t;
2023 	int32_t tt;
2024 	uint32_t ret_val;
2025 
2026 	t = TICKS_2_MSEC((tp->t_srtt >> TCP_RTT_SHIFT) + ((tp->t_rttvar * 4) >> TCP_RTT_SHIFT));
2027 	TCPT_RANGESET(tt, t * tcp_backoff[tp->t_rxtshift],
2028 	    tcp_persmin, tcp_persmax);
2029 	if (tp->t_rxtshift < TCP_MAXRXTSHIFT)
2030 		tp->t_rxtshift++;
2031 	rack->r_ctl.rc_hpts_flags |= PACE_TMR_PERSIT;
2032 	ret_val = (uint32_t)tt;
2033 	return (ret_val);
2034 }
2035 
2036 static uint32_t
2037 rack_timer_start(struct tcpcb *tp, struct tcp_rack *rack, uint32_t cts)
2038 {
2039 	/*
2040 	 * Start the FR timer, we do this based on getting the first one in
2041 	 * the rc_tmap. Note that if its NULL we must stop the timer. in all
2042 	 * events we need to stop the running timer (if its running) before
2043 	 * starting the new one.
2044 	 */
2045 	uint32_t thresh, exp, to, srtt, time_since_sent;
2046 	uint32_t srtt_cur;
2047 	int32_t idx;
2048 	int32_t is_tlp_timer = 0;
2049 	struct rack_sendmap *rsm;
2050 
2051 	if (rack->t_timers_stopped) {
2052 		/* All timers have been stopped none are to run */
2053 		return (0);
2054 	}
2055 	if (rack->rc_in_persist) {
2056 		/* We can't start any timer in persists */
2057 		return (rack_get_persists_timer_val(tp, rack));
2058 	}
2059 	if (tp->t_state < TCPS_ESTABLISHED)
2060 		goto activate_rxt;
2061 	rsm = TAILQ_FIRST(&rack->r_ctl.rc_tmap);
2062 	if (rsm == NULL) {
2063 		/* Nothing on the send map */
2064 activate_rxt:
2065 		if (SEQ_LT(tp->snd_una, tp->snd_max) || sbavail(&(tp->t_inpcb->inp_socket->so_snd))) {
2066 			rack->r_ctl.rc_hpts_flags |= PACE_TMR_RXT;
2067 			to = TICKS_2_MSEC(tp->t_rxtcur);
2068 			if (to == 0)
2069 				to = 1;
2070 			return (to);
2071 		}
2072 		return (0);
2073 	}
2074 	if (rsm->r_flags & RACK_ACKED) {
2075 		rsm = rack_find_lowest_rsm(rack);
2076 		if (rsm == NULL) {
2077 			/* No lowest? */
2078 			goto activate_rxt;
2079 		}
2080 	}
2081 	/* Convert from ms to usecs */
2082 	if (rsm->r_flags & RACK_SACK_PASSED) {
2083 		if ((tp->t_flags & TF_SENTFIN) &&
2084 		    ((tp->snd_max - tp->snd_una) == 1) &&
2085 		    (rsm->r_flags & RACK_HAS_FIN)) {
2086 			/*
2087 			 * We don't start a rack timer if all we have is a
2088 			 * FIN outstanding.
2089 			 */
2090 			goto activate_rxt;
2091 		}
2092 		if (tp->t_srtt) {
2093 			srtt_cur = (tp->t_srtt >> TCP_RTT_SHIFT);
2094 			srtt = TICKS_2_MSEC(srtt_cur);
2095 		} else
2096 			srtt = RACK_INITIAL_RTO;
2097 
2098 		thresh = rack_calc_thresh_rack(rack, srtt, cts);
2099 		idx = rsm->r_rtr_cnt - 1;
2100 		exp = rsm->r_tim_lastsent[idx] + thresh;
2101 		if (SEQ_GEQ(exp, cts)) {
2102 			to = exp - cts;
2103 			if (to < rack->r_ctl.rc_min_to) {
2104 				to = rack->r_ctl.rc_min_to;
2105 			}
2106 		} else {
2107 			to = rack->r_ctl.rc_min_to;
2108 		}
2109 	} else {
2110 		/* Ok we need to do a TLP not RACK */
2111 		if ((rack->rc_tlp_in_progress != 0) ||
2112 		    (rack->r_ctl.rc_tlp_rtx_out != 0)) {
2113 			/*
2114 			 * The previous send was a TLP or a tlp_rtx is in
2115 			 * process.
2116 			 */
2117 			goto activate_rxt;
2118 		}
2119 		rsm = TAILQ_LAST_FAST(&rack->r_ctl.rc_tmap, rack_sendmap, r_tnext);
2120 		if (rsm == NULL) {
2121 			/* We found no rsm to TLP with. */
2122 			goto activate_rxt;
2123 		}
2124 		if (rsm->r_flags & RACK_HAS_FIN) {
2125 			/* If its a FIN we dont do TLP */
2126 			rsm = NULL;
2127 			goto activate_rxt;
2128 		}
2129 		idx = rsm->r_rtr_cnt - 1;
2130 		if (TSTMP_GT(cts,  rsm->r_tim_lastsent[idx]))
2131 			time_since_sent = cts - rsm->r_tim_lastsent[idx];
2132 		else
2133 			time_since_sent = 0;
2134 		is_tlp_timer = 1;
2135 		if (tp->t_srtt) {
2136 			srtt_cur = (tp->t_srtt >> TCP_RTT_SHIFT);
2137 			srtt = TICKS_2_MSEC(srtt_cur);
2138 		} else
2139 			srtt = RACK_INITIAL_RTO;
2140 		thresh = rack_calc_thresh_tlp(tp, rack, rsm, srtt);
2141 		if (thresh > time_since_sent)
2142 			to = thresh - time_since_sent;
2143 		else
2144 			to = rack->r_ctl.rc_min_to;
2145 		if (to > TCPTV_REXMTMAX) {
2146 			/*
2147 			 * If the TLP time works out to larger than the max
2148 			 * RTO lets not do TLP.. just RTO.
2149 			 */
2150 			goto activate_rxt;
2151 		}
2152 		if (rsm->r_start != rack->r_ctl.rc_last_tlp_seq) {
2153 			/*
2154 			 * The tail is no longer the last one I did a probe
2155 			 * on
2156 			 */
2157 			rack->r_ctl.rc_tlp_seg_send_cnt = 0;
2158 			rack->r_ctl.rc_last_tlp_seq = rsm->r_start;
2159 		}
2160 	}
2161 	if (is_tlp_timer == 0) {
2162 		rack->r_ctl.rc_hpts_flags |= PACE_TMR_RACK;
2163 	} else {
2164 		if ((rack->r_ctl.rc_tlp_send_cnt > rack_tlp_max_resend) ||
2165 		    (rack->r_ctl.rc_tlp_seg_send_cnt > rack_tlp_max_resend)) {
2166 			/*
2167 			 * We have exceeded how many times we can retran the
2168 			 * current TLP timer, switch to the RTO timer.
2169 			 */
2170 			goto activate_rxt;
2171 		} else {
2172 			rack->r_ctl.rc_hpts_flags |= PACE_TMR_TLP;
2173 		}
2174 	}
2175 	if (to == 0)
2176 		to = 1;
2177 	return (to);
2178 }
2179 
2180 static void
2181 rack_enter_persist(struct tcpcb *tp, struct tcp_rack *rack, uint32_t cts)
2182 {
2183 	if (rack->rc_in_persist == 0) {
2184 		if (((tp->t_flags & TF_SENTFIN) == 0) &&
2185 		    (tp->snd_max - tp->snd_una) >= sbavail(&rack->rc_inp->inp_socket->so_snd))
2186 			/* Must need to send more data to enter persist */
2187 			return;
2188 		rack->r_ctl.rc_went_idle_time = cts;
2189 		rack_timer_cancel(tp, rack, cts, __LINE__);
2190 		tp->t_rxtshift = 0;
2191 		rack->rc_in_persist = 1;
2192 	}
2193 }
2194 
2195 static void
2196 rack_exit_persist(struct tcpcb *tp, struct tcp_rack *rack)
2197 {
2198 	if (rack->rc_inp->inp_in_hpts)  {
2199 		tcp_hpts_remove(rack->rc_inp, HPTS_REMOVE_OUTPUT);
2200 		rack->r_ctl.rc_hpts_flags  = 0;
2201 	}
2202 	rack->rc_in_persist = 0;
2203 	rack->r_ctl.rc_went_idle_time = 0;
2204 	tp->t_flags &= ~TF_FORCEDATA;
2205 	tp->t_rxtshift = 0;
2206 }
2207 
2208 static void
2209 rack_start_hpts_timer(struct tcp_rack *rack, struct tcpcb *tp, uint32_t cts, int32_t line,
2210     int32_t slot, uint32_t tot_len_this_send, int32_t frm_out_sbavail)
2211 {
2212 	struct inpcb *inp;
2213 	uint32_t delayed_ack = 0;
2214 	uint32_t hpts_timeout;
2215 	uint8_t stopped;
2216 	uint32_t left = 0;
2217 
2218 	inp = tp->t_inpcb;
2219 	if (inp->inp_in_hpts) {
2220 		/* A previous call is already set up */
2221 		return;
2222 	}
2223 	if (tp->t_state == TCPS_CLOSED) {
2224 		return;
2225 	}
2226 	stopped = rack->rc_tmr_stopped;
2227 	if (stopped && TSTMP_GT(rack->r_ctl.rc_timer_exp, cts)) {
2228 		left = rack->r_ctl.rc_timer_exp - cts;
2229 	}
2230 	rack->r_ctl.rc_timer_exp = 0;
2231 	if (rack->rc_inp->inp_in_hpts == 0) {
2232 		rack->r_ctl.rc_hpts_flags = 0;
2233 	}
2234 	if (slot) {
2235 		/* We are hptsi too */
2236 		rack->r_ctl.rc_hpts_flags |= PACE_PKT_OUTPUT;
2237 	} else if (rack->r_ctl.rc_hpts_flags & PACE_PKT_OUTPUT) {
2238 		/*
2239 		 * We are still left on the hpts when the to goes
2240 		 * it will be for output.
2241 		 */
2242 		if (TSTMP_GT(cts, rack->r_ctl.rc_last_output_to))
2243 			slot = cts - rack->r_ctl.rc_last_output_to;
2244 		else
2245 			slot = 1;
2246 	}
2247 	if ((tp->snd_wnd == 0) && TCPS_HAVEESTABLISHED(tp->t_state)) {
2248 		/* No send window.. we must enter persist */
2249 		rack_enter_persist(tp, rack, cts);
2250 	} else if ((frm_out_sbavail &&
2251 		    (frm_out_sbavail > (tp->snd_max - tp->snd_una)) &&
2252 		    (tp->snd_wnd < tp->t_maxseg)) &&
2253 	    TCPS_HAVEESTABLISHED(tp->t_state)) {
2254 		/*
2255 		 * If we have no window or we can't send a segment (and have
2256 		 * data to send.. we cheat here and frm_out_sbavail is
2257 		 * passed in with the sbavail(sb) only from bbr_output) and
2258 		 * we are established, then we must enter persits (if not
2259 		 * already in persits).
2260 		 */
2261 		rack_enter_persist(tp, rack, cts);
2262 	}
2263 	hpts_timeout = rack_timer_start(tp, rack, cts);
2264 	if (tp->t_flags & TF_DELACK) {
2265 		delayed_ack = TICKS_2_MSEC(tcp_delacktime);
2266 		rack->r_ctl.rc_hpts_flags |= PACE_TMR_DELACK;
2267 	}
2268 	if (delayed_ack && ((hpts_timeout == 0) ||
2269 			    (delayed_ack < hpts_timeout)))
2270 		hpts_timeout = delayed_ack;
2271 	else
2272 		rack->r_ctl.rc_hpts_flags &= ~PACE_TMR_DELACK;
2273 	/*
2274 	 * If no timers are going to run and we will fall off the hptsi
2275 	 * wheel, we resort to a keep-alive timer if its configured.
2276 	 */
2277 	if ((hpts_timeout == 0) &&
2278 	    (slot == 0)) {
2279 		if ((tcp_always_keepalive || inp->inp_socket->so_options & SO_KEEPALIVE) &&
2280 		    (tp->t_state <= TCPS_CLOSING)) {
2281 			/*
2282 			 * Ok we have no timer (persists, rack, tlp, rxt  or
2283 			 * del-ack), we don't have segments being paced. So
2284 			 * all that is left is the keepalive timer.
2285 			 */
2286 			if (TCPS_HAVEESTABLISHED(tp->t_state)) {
2287 				/* Get the established keep-alive time */
2288 				hpts_timeout = TP_KEEPIDLE(tp);
2289 			} else {
2290 				/* Get the initial setup keep-alive time */
2291 				hpts_timeout = TP_KEEPINIT(tp);
2292 			}
2293 			rack->r_ctl.rc_hpts_flags |= PACE_TMR_KEEP;
2294 		}
2295 	}
2296 	if (left && (stopped & (PACE_TMR_KEEP | PACE_TMR_DELACK)) ==
2297 	    (rack->r_ctl.rc_hpts_flags & PACE_TMR_MASK)) {
2298 		/*
2299 		 * RACK, TLP, persists and RXT timers all are restartable
2300 		 * based on actions input .. i.e we received a packet (ack
2301 		 * or sack) and that changes things (rw, or snd_una etc).
2302 		 * Thus we can restart them with a new value. For
2303 		 * keep-alive, delayed_ack we keep track of what was left
2304 		 * and restart the timer with a smaller value.
2305 		 */
2306 		if (left < hpts_timeout)
2307 			hpts_timeout = left;
2308 	}
2309 	if (hpts_timeout) {
2310 		/*
2311 		 * Hack alert for now we can't time-out over 2,147,483
2312 		 * seconds (a bit more than 596 hours), which is probably ok
2313 		 * :).
2314 		 */
2315 		if (hpts_timeout > 0x7ffffffe)
2316 			hpts_timeout = 0x7ffffffe;
2317 		rack->r_ctl.rc_timer_exp = cts + hpts_timeout;
2318 	}
2319 	if (slot) {
2320 		rack->r_ctl.rc_last_output_to = cts + slot;
2321 		if ((hpts_timeout == 0) || (hpts_timeout > slot)) {
2322 			if (rack->rc_inp->inp_in_hpts == 0)
2323 				tcp_hpts_insert(tp->t_inpcb, HPTS_MS_TO_SLOTS(slot));
2324 			rack_log_to_start(rack, cts, hpts_timeout, slot, 1);
2325 		} else {
2326 			/*
2327 			 * Arrange for the hpts to kick back in after the
2328 			 * t-o if the t-o does not cause a send.
2329 			 */
2330 			if (rack->rc_inp->inp_in_hpts == 0)
2331 				tcp_hpts_insert(tp->t_inpcb, HPTS_MS_TO_SLOTS(hpts_timeout));
2332 			rack_log_to_start(rack, cts, hpts_timeout, slot, 0);
2333 		}
2334 	} else if (hpts_timeout) {
2335 		if (rack->rc_inp->inp_in_hpts == 0)
2336 			tcp_hpts_insert(tp->t_inpcb, HPTS_MS_TO_SLOTS(hpts_timeout));
2337 		rack_log_to_start(rack, cts, hpts_timeout, slot, 0);
2338 	} else {
2339 		/* No timer starting */
2340 #ifdef INVARIANTS
2341 		if (SEQ_GT(tp->snd_max, tp->snd_una)) {
2342 			panic("tp:%p rack:%p tlts:%d cts:%u slot:%u pto:%u -- no timer started?",
2343 			    tp, rack, tot_len_this_send, cts, slot, hpts_timeout);
2344 		}
2345 #endif
2346 	}
2347 	rack->rc_tmr_stopped = 0;
2348 	if (slot)
2349 		rack_log_type_bbrsnd(rack, tot_len_this_send, slot, cts);
2350 }
2351 
2352 /*
2353  * RACK Timer, here we simply do logging and house keeping.
2354  * the normal rack_output() function will call the
2355  * appropriate thing to check if we need to do a RACK retransmit.
2356  * We return 1, saying don't proceed with rack_output only
2357  * when all timers have been stopped (destroyed PCB?).
2358  */
2359 static int
2360 rack_timeout_rack(struct tcpcb *tp, struct tcp_rack *rack, uint32_t cts)
2361 {
2362 	/*
2363 	 * This timer simply provides an internal trigger to send out data.
2364 	 * The check_recovery_mode call will see if there are needed
2365 	 * retransmissions, if so we will enter fast-recovery. The output
2366 	 * call may or may not do the same thing depending on sysctl
2367 	 * settings.
2368 	 */
2369 	struct rack_sendmap *rsm;
2370 	int32_t recovery;
2371 
2372 	if (tp->t_timers->tt_flags & TT_STOPPED) {
2373 		return (1);
2374 	}
2375 	if (TSTMP_LT(cts, rack->r_ctl.rc_timer_exp)) {
2376 		/* Its not time yet */
2377 		return (0);
2378 	}
2379 	rack_log_to_event(rack, RACK_TO_FRM_RACK);
2380 	recovery = IN_RECOVERY(tp->t_flags);
2381 	counter_u64_add(rack_to_tot, 1);
2382 	if (rack->r_state && (rack->r_state != tp->t_state))
2383 		rack_set_state(tp, rack);
2384 	rsm = rack_check_recovery_mode(tp, cts);
2385 	if (rsm) {
2386 		uint32_t rtt;
2387 
2388 		rtt = rack->rc_rack_rtt;
2389 		if (rtt == 0)
2390 			rtt = 1;
2391 		if ((recovery == 0) &&
2392 		    (rack->r_ctl.rc_prr_sndcnt < tp->t_maxseg)) {
2393 			/*
2394 			 * The rack-timeout that enter's us into recovery
2395 			 * will force out one MSS and set us up so that we
2396 			 * can do one more send in 2*rtt (transitioning the
2397 			 * rack timeout into a rack-tlp).
2398 			 */
2399 			rack->r_ctl.rc_prr_sndcnt = tp->t_maxseg;
2400 		} else if ((rack->r_ctl.rc_prr_sndcnt < tp->t_maxseg) &&
2401 		    ((rsm->r_end - rsm->r_start) > rack->r_ctl.rc_prr_sndcnt)) {
2402 			/*
2403 			 * When a rack timer goes, we have to send at
2404 			 * least one segment. They will be paced a min of 1ms
2405 			 * apart via the next rack timer (or further
2406 			 * if the rack timer dictates it).
2407 			 */
2408 			rack->r_ctl.rc_prr_sndcnt = tp->t_maxseg;
2409 		}
2410 	} else {
2411 		/* This is a case that should happen rarely if ever */
2412 		counter_u64_add(rack_tlp_does_nada, 1);
2413 #ifdef TCP_BLACKBOX
2414 		tcp_log_dump_tp_logbuf(tp, "nada counter trips", M_NOWAIT, true);
2415 #endif
2416 		rack->r_ctl.rc_resend = TAILQ_FIRST(&rack->r_ctl.rc_tmap);
2417 	}
2418 	rack->r_ctl.rc_hpts_flags &= ~PACE_TMR_RACK;
2419 	return (0);
2420 }
2421 
2422 /*
2423  * TLP Timer, here we simply setup what segment we want to
2424  * have the TLP expire on, the normal rack_output() will then
2425  * send it out.
2426  *
2427  * We return 1, saying don't proceed with rack_output only
2428  * when all timers have been stopped (destroyed PCB?).
2429  */
2430 static int
2431 rack_timeout_tlp(struct tcpcb *tp, struct tcp_rack *rack, uint32_t cts)
2432 {
2433 	/*
2434 	 * Tail Loss Probe.
2435 	 */
2436 	struct rack_sendmap *rsm = NULL;
2437 	struct socket *so;
2438 	uint32_t amm, old_prr_snd = 0;
2439 	uint32_t out, avail;
2440 
2441 	if (tp->t_timers->tt_flags & TT_STOPPED) {
2442 		return (1);
2443 	}
2444 	if (TSTMP_LT(cts, rack->r_ctl.rc_timer_exp)) {
2445 		/* Its not time yet */
2446 		return (0);
2447 	}
2448 	if (rack_progress_timeout_check(tp)) {
2449 		tcp_set_inp_to_drop(tp->t_inpcb, ETIMEDOUT);
2450 		return (1);
2451 	}
2452 	/*
2453 	 * A TLP timer has expired. We have been idle for 2 rtts. So we now
2454 	 * need to figure out how to force a full MSS segment out.
2455 	 */
2456 	rack_log_to_event(rack, RACK_TO_FRM_TLP);
2457 	counter_u64_add(rack_tlp_tot, 1);
2458 	if (rack->r_state && (rack->r_state != tp->t_state))
2459 		rack_set_state(tp, rack);
2460 	so = tp->t_inpcb->inp_socket;
2461 	avail = sbavail(&so->so_snd);
2462 	out = tp->snd_max - tp->snd_una;
2463 	rack->rc_timer_up = 1;
2464 	/*
2465 	 * If we are in recovery we can jazz out a segment if new data is
2466 	 * present simply by setting rc_prr_sndcnt to a segment.
2467 	 */
2468 	if ((avail > out) &&
2469 	    ((rack_always_send_oldest == 0) || (TAILQ_EMPTY(&rack->r_ctl.rc_tmap)))) {
2470 		/* New data is available */
2471 		amm = avail - out;
2472 		if (amm > tp->t_maxseg) {
2473 			amm = tp->t_maxseg;
2474 		} else if ((amm < tp->t_maxseg) && ((tp->t_flags & TF_NODELAY) == 0)) {
2475 			/* not enough to fill a MTU and no-delay is off */
2476 			goto need_retran;
2477 		}
2478 		if (IN_RECOVERY(tp->t_flags)) {
2479 			/* Unlikely */
2480 			old_prr_snd = rack->r_ctl.rc_prr_sndcnt;
2481 			if (out + amm <= tp->snd_wnd)
2482 				rack->r_ctl.rc_prr_sndcnt = amm;
2483 			else
2484 				goto need_retran;
2485 		} else {
2486 			/* Set the send-new override */
2487 			if (out + amm <= tp->snd_wnd)
2488 				rack->r_ctl.rc_tlp_new_data = amm;
2489 			else
2490 				goto need_retran;
2491 		}
2492 		rack->r_ctl.rc_tlp_seg_send_cnt = 0;
2493 		rack->r_ctl.rc_last_tlp_seq = tp->snd_max;
2494 		rack->r_ctl.rc_tlpsend = NULL;
2495 		counter_u64_add(rack_tlp_newdata, 1);
2496 		goto send;
2497 	}
2498 need_retran:
2499 	/*
2500 	 * Ok we need to arrange the last un-acked segment to be re-sent, or
2501 	 * optionally the first un-acked segment.
2502 	 */
2503 	if (rack_always_send_oldest)
2504 		rsm = TAILQ_FIRST(&rack->r_ctl.rc_tmap);
2505 	else {
2506 		rsm = TAILQ_LAST_FAST(&rack->r_ctl.rc_map, rack_sendmap, r_next);
2507 		if (rsm && (rsm->r_flags & (RACK_ACKED | RACK_HAS_FIN))) {
2508 			rsm = rack_find_high_nonack(rack, rsm);
2509 		}
2510 	}
2511 	if (rsm == NULL) {
2512 		counter_u64_add(rack_tlp_does_nada, 1);
2513 #ifdef TCP_BLACKBOX
2514 		tcp_log_dump_tp_logbuf(tp, "nada counter trips", M_NOWAIT, true);
2515 #endif
2516 		goto out;
2517 	}
2518 	if ((rsm->r_end - rsm->r_start) > tp->t_maxseg) {
2519 		/*
2520 		 * We need to split this the last segment in two.
2521 		 */
2522 		int32_t idx;
2523 		struct rack_sendmap *nrsm;
2524 
2525 		nrsm = rack_alloc(rack);
2526 		if (nrsm == NULL) {
2527 			/*
2528 			 * No memory to split, we will just exit and punt
2529 			 * off to the RXT timer.
2530 			 */
2531 			counter_u64_add(rack_tlp_does_nada, 1);
2532 			goto out;
2533 		}
2534 		nrsm->r_start = (rsm->r_end - tp->t_maxseg);
2535 		nrsm->r_end = rsm->r_end;
2536 		nrsm->r_rtr_cnt = rsm->r_rtr_cnt;
2537 		nrsm->r_flags = rsm->r_flags;
2538 		nrsm->r_sndcnt = rsm->r_sndcnt;
2539 		nrsm->r_rtr_bytes = 0;
2540 		rsm->r_end = nrsm->r_start;
2541 		for (idx = 0; idx < nrsm->r_rtr_cnt; idx++) {
2542 			nrsm->r_tim_lastsent[idx] = rsm->r_tim_lastsent[idx];
2543 		}
2544 		TAILQ_INSERT_AFTER(&rack->r_ctl.rc_map, rsm, nrsm, r_next);
2545 		if (rsm->r_in_tmap) {
2546 			TAILQ_INSERT_AFTER(&rack->r_ctl.rc_tmap, rsm, nrsm, r_tnext);
2547 			nrsm->r_in_tmap = 1;
2548 		}
2549 		rsm->r_flags &= (~RACK_HAS_FIN);
2550 		rsm = nrsm;
2551 	}
2552 	rack->r_ctl.rc_tlpsend = rsm;
2553 	rack->r_ctl.rc_tlp_rtx_out = 1;
2554 	if (rsm->r_start == rack->r_ctl.rc_last_tlp_seq) {
2555 		rack->r_ctl.rc_tlp_seg_send_cnt++;
2556 		tp->t_rxtshift++;
2557 	} else {
2558 		rack->r_ctl.rc_last_tlp_seq = rsm->r_start;
2559 		rack->r_ctl.rc_tlp_seg_send_cnt = 1;
2560 	}
2561 send:
2562 	rack->r_ctl.rc_tlp_send_cnt++;
2563 	if (rack->r_ctl.rc_tlp_send_cnt > rack_tlp_max_resend) {
2564 		/*
2565 		 * Can't [re]/transmit a segment we have not heard from the
2566 		 * peer in max times. We need the retransmit timer to take
2567 		 * over.
2568 		 */
2569 restore:
2570 		rack->r_ctl.rc_tlpsend = NULL;
2571 		if (rsm)
2572 			rsm->r_flags &= ~RACK_TLP;
2573 		rack->r_ctl.rc_prr_sndcnt = old_prr_snd;
2574 		counter_u64_add(rack_tlp_retran_fail, 1);
2575 		goto out;
2576 	} else if (rsm) {
2577 		rsm->r_flags |= RACK_TLP;
2578 	}
2579 	if (rsm && (rsm->r_start == rack->r_ctl.rc_last_tlp_seq) &&
2580 	    (rack->r_ctl.rc_tlp_seg_send_cnt > rack_tlp_max_resend)) {
2581 		/*
2582 		 * We don't want to send a single segment more than the max
2583 		 * either.
2584 		 */
2585 		goto restore;
2586 	}
2587 	rack->r_timer_override = 1;
2588 	rack->r_tlp_running = 1;
2589 	rack->rc_tlp_in_progress = 1;
2590 	rack->r_ctl.rc_hpts_flags &= ~PACE_TMR_TLP;
2591 	return (0);
2592 out:
2593 	rack->rc_timer_up = 0;
2594 	rack->r_ctl.rc_hpts_flags &= ~PACE_TMR_TLP;
2595 	return (0);
2596 }
2597 
2598 /*
2599  * Delayed ack Timer, here we simply need to setup the
2600  * ACK_NOW flag and remove the DELACK flag. From there
2601  * the output routine will send the ack out.
2602  *
2603  * We only return 1, saying don't proceed, if all timers
2604  * are stopped (destroyed PCB?).
2605  */
2606 static int
2607 rack_timeout_delack(struct tcpcb *tp, struct tcp_rack *rack, uint32_t cts)
2608 {
2609 	if (tp->t_timers->tt_flags & TT_STOPPED) {
2610 		return (1);
2611 	}
2612 	rack_log_to_event(rack, RACK_TO_FRM_DELACK);
2613 	tp->t_flags &= ~TF_DELACK;
2614 	tp->t_flags |= TF_ACKNOW;
2615 	TCPSTAT_INC(tcps_delack);
2616 	rack->r_ctl.rc_hpts_flags &= ~PACE_TMR_DELACK;
2617 	return (0);
2618 }
2619 
2620 /*
2621  * Persists timer, here we simply need to setup the
2622  * FORCE-DATA flag the output routine will send
2623  * the one byte send.
2624  *
2625  * We only return 1, saying don't proceed, if all timers
2626  * are stopped (destroyed PCB?).
2627  */
2628 static int
2629 rack_timeout_persist(struct tcpcb *tp, struct tcp_rack *rack, uint32_t cts)
2630 {
2631 	struct inpcb *inp;
2632 	int32_t retval = 0;
2633 
2634 	inp = tp->t_inpcb;
2635 
2636 	if (tp->t_timers->tt_flags & TT_STOPPED) {
2637 		return (1);
2638 	}
2639 	if (rack->rc_in_persist == 0)
2640 		return (0);
2641 	if (rack_progress_timeout_check(tp)) {
2642 		tcp_set_inp_to_drop(inp, ETIMEDOUT);
2643 		return (1);
2644 	}
2645 	KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
2646 	/*
2647 	 * Persistence timer into zero window. Force a byte to be output, if
2648 	 * possible.
2649 	 */
2650 	TCPSTAT_INC(tcps_persisttimeo);
2651 	/*
2652 	 * Hack: if the peer is dead/unreachable, we do not time out if the
2653 	 * window is closed.  After a full backoff, drop the connection if
2654 	 * the idle time (no responses to probes) reaches the maximum
2655 	 * backoff that we would use if retransmitting.
2656 	 */
2657 	if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
2658 	    (ticks - tp->t_rcvtime >= tcp_maxpersistidle ||
2659 	    ticks - tp->t_rcvtime >= TCP_REXMTVAL(tp) * tcp_totbackoff)) {
2660 		TCPSTAT_INC(tcps_persistdrop);
2661 		retval = 1;
2662 		tcp_set_inp_to_drop(rack->rc_inp, ETIMEDOUT);
2663 		goto out;
2664 	}
2665 	if ((sbavail(&rack->rc_inp->inp_socket->so_snd) == 0) &&
2666 	    tp->snd_una == tp->snd_max)
2667 		rack_exit_persist(tp, rack);
2668 	rack->r_ctl.rc_hpts_flags &= ~PACE_TMR_PERSIT;
2669 	/*
2670 	 * If the user has closed the socket then drop a persisting
2671 	 * connection after a much reduced timeout.
2672 	 */
2673 	if (tp->t_state > TCPS_CLOSE_WAIT &&
2674 	    (ticks - tp->t_rcvtime) >= TCPTV_PERSMAX) {
2675 		retval = 1;
2676 		TCPSTAT_INC(tcps_persistdrop);
2677 		tcp_set_inp_to_drop(rack->rc_inp, ETIMEDOUT);
2678 		goto out;
2679 	}
2680 	tp->t_flags |= TF_FORCEDATA;
2681 out:
2682 	rack_log_to_event(rack, RACK_TO_FRM_PERSIST);
2683 	return (retval);
2684 }
2685 
2686 /*
2687  * If a keepalive goes off, we had no other timers
2688  * happening. We always return 1 here since this
2689  * routine either drops the connection or sends
2690  * out a segment with respond.
2691  */
2692 static int
2693 rack_timeout_keepalive(struct tcpcb *tp, struct tcp_rack *rack, uint32_t cts)
2694 {
2695 	struct tcptemp *t_template;
2696 	struct inpcb *inp;
2697 
2698 	if (tp->t_timers->tt_flags & TT_STOPPED) {
2699 		return (1);
2700 	}
2701 	rack->r_ctl.rc_hpts_flags &= ~PACE_TMR_KEEP;
2702 	inp = tp->t_inpcb;
2703 	rack_log_to_event(rack, RACK_TO_FRM_KEEP);
2704 	/*
2705 	 * Keep-alive timer went off; send something or drop connection if
2706 	 * idle for too long.
2707 	 */
2708 	TCPSTAT_INC(tcps_keeptimeo);
2709 	if (tp->t_state < TCPS_ESTABLISHED)
2710 		goto dropit;
2711 	if ((tcp_always_keepalive || inp->inp_socket->so_options & SO_KEEPALIVE) &&
2712 	    tp->t_state <= TCPS_CLOSING) {
2713 		if (ticks - tp->t_rcvtime >= TP_KEEPIDLE(tp) + TP_MAXIDLE(tp))
2714 			goto dropit;
2715 		/*
2716 		 * Send a packet designed to force a response if the peer is
2717 		 * up and reachable: either an ACK if the connection is
2718 		 * still alive, or an RST if the peer has closed the
2719 		 * connection due to timeout or reboot. Using sequence
2720 		 * number tp->snd_una-1 causes the transmitted zero-length
2721 		 * segment to lie outside the receive window; by the
2722 		 * protocol spec, this requires the correspondent TCP to
2723 		 * respond.
2724 		 */
2725 		TCPSTAT_INC(tcps_keepprobe);
2726 		t_template = tcpip_maketemplate(inp);
2727 		if (t_template) {
2728 			tcp_respond(tp, t_template->tt_ipgen,
2729 			    &t_template->tt_t, (struct mbuf *)NULL,
2730 			    tp->rcv_nxt, tp->snd_una - 1, 0);
2731 			free(t_template, M_TEMP);
2732 		}
2733 	}
2734 	rack_start_hpts_timer(rack, tp, cts, __LINE__, 0, 0, 0);
2735 	return (1);
2736 dropit:
2737 	TCPSTAT_INC(tcps_keepdrops);
2738 	tcp_set_inp_to_drop(rack->rc_inp, ETIMEDOUT);
2739 	return (1);
2740 }
2741 
2742 /*
2743  * Retransmit helper function, clear up all the ack
2744  * flags and take care of important book keeping.
2745  */
2746 static void
2747 rack_remxt_tmr(struct tcpcb *tp)
2748 {
2749 	/*
2750 	 * The retransmit timer went off, all sack'd blocks must be
2751 	 * un-acked.
2752 	 */
2753 	struct rack_sendmap *rsm, *trsm = NULL;
2754 	struct tcp_rack *rack;
2755 	int32_t cnt = 0;
2756 
2757 	rack = (struct tcp_rack *)tp->t_fb_ptr;
2758 	rack_timer_cancel(tp, rack, tcp_ts_getticks(), __LINE__);
2759 	rack_log_to_event(rack, RACK_TO_FRM_TMR);
2760 	if (rack->r_state && (rack->r_state != tp->t_state))
2761 		rack_set_state(tp, rack);
2762 	/*
2763 	 * Ideally we would like to be able to
2764 	 * mark SACK-PASS on anything not acked here.
2765 	 * However, if we do that we would burst out
2766 	 * all that data 1ms apart. This would be unwise,
2767 	 * so for now we will just let the normal rxt timer
2768 	 * and tlp timer take care of it.
2769 	 */
2770 	TAILQ_FOREACH(rsm, &rack->r_ctl.rc_map, r_next) {
2771 		if (rsm->r_flags & RACK_ACKED) {
2772 			cnt++;
2773 			rsm->r_sndcnt = 0;
2774 			if (rsm->r_in_tmap == 0) {
2775 				/* We must re-add it back to the tlist */
2776 				if (trsm == NULL) {
2777 					TAILQ_INSERT_HEAD(&rack->r_ctl.rc_tmap, rsm, r_tnext);
2778 				} else {
2779 					TAILQ_INSERT_AFTER(&rack->r_ctl.rc_tmap, trsm, rsm, r_tnext);
2780 				}
2781 				rsm->r_in_tmap = 1;
2782 				trsm = rsm;
2783 			}
2784 		}
2785 		rsm->r_flags &= ~(RACK_ACKED | RACK_SACK_PASSED | RACK_WAS_SACKPASS);
2786 	}
2787 	/* Clear the count (we just un-acked them) */
2788 	rack->r_ctl.rc_sacked = 0;
2789 	/* Clear the tlp rtx mark */
2790 	rack->r_ctl.rc_tlp_rtx_out = 0;
2791 	rack->r_ctl.rc_tlp_seg_send_cnt = 0;
2792 	rack->r_ctl.rc_resend = TAILQ_FIRST(&rack->r_ctl.rc_map);
2793 	/* Setup so we send one segment */
2794 	if (rack->r_ctl.rc_prr_sndcnt < tp->t_maxseg)
2795 		rack->r_ctl.rc_prr_sndcnt = tp->t_maxseg;
2796 	rack->r_timer_override = 1;
2797 }
2798 
2799 /*
2800  * Re-transmit timeout! If we drop the PCB we will return 1, otherwise
2801  * we will setup to retransmit the lowest seq number outstanding.
2802  */
2803 static int
2804 rack_timeout_rxt(struct tcpcb *tp, struct tcp_rack *rack, uint32_t cts)
2805 {
2806 	int32_t rexmt;
2807 	struct inpcb *inp;
2808 	int32_t retval = 0;
2809 
2810 	inp = tp->t_inpcb;
2811 	if (tp->t_timers->tt_flags & TT_STOPPED) {
2812 		return (1);
2813 	}
2814 	if (rack_progress_timeout_check(tp)) {
2815 		tcp_set_inp_to_drop(inp, ETIMEDOUT);
2816 		return (1);
2817 	}
2818 	rack->r_ctl.rc_hpts_flags &= ~PACE_TMR_RXT;
2819 	if (TCPS_HAVEESTABLISHED(tp->t_state) &&
2820 	    (tp->snd_una == tp->snd_max)) {
2821 		/* Nothing outstanding .. nothing to do */
2822 		return (0);
2823 	}
2824 	/*
2825 	 * Retransmission timer went off.  Message has not been acked within
2826 	 * retransmit interval.  Back off to a longer retransmit interval
2827 	 * and retransmit one segment.
2828 	 */
2829 	if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) {
2830 		tp->t_rxtshift = TCP_MAXRXTSHIFT;
2831 		TCPSTAT_INC(tcps_timeoutdrop);
2832 		retval = 1;
2833 		tcp_set_inp_to_drop(rack->rc_inp,
2834 		    (tp->t_softerror ? (uint16_t) tp->t_softerror : ETIMEDOUT));
2835 		goto out;
2836 	}
2837 	rack_remxt_tmr(tp);
2838 	if (tp->t_state == TCPS_SYN_SENT) {
2839 		/*
2840 		 * If the SYN was retransmitted, indicate CWND to be limited
2841 		 * to 1 segment in cc_conn_init().
2842 		 */
2843 		tp->snd_cwnd = 1;
2844 	} else if (tp->t_rxtshift == 1) {
2845 		/*
2846 		 * first retransmit; record ssthresh and cwnd so they can be
2847 		 * recovered if this turns out to be a "bad" retransmit. A
2848 		 * retransmit is considered "bad" if an ACK for this segment
2849 		 * is received within RTT/2 interval; the assumption here is
2850 		 * that the ACK was already in flight.  See "On Estimating
2851 		 * End-to-End Network Path Properties" by Allman and Paxson
2852 		 * for more details.
2853 		 */
2854 		tp->snd_cwnd_prev = tp->snd_cwnd;
2855 		tp->snd_ssthresh_prev = tp->snd_ssthresh;
2856 		tp->snd_recover_prev = tp->snd_recover;
2857 		if (IN_FASTRECOVERY(tp->t_flags))
2858 			tp->t_flags |= TF_WASFRECOVERY;
2859 		else
2860 			tp->t_flags &= ~TF_WASFRECOVERY;
2861 		if (IN_CONGRECOVERY(tp->t_flags))
2862 			tp->t_flags |= TF_WASCRECOVERY;
2863 		else
2864 			tp->t_flags &= ~TF_WASCRECOVERY;
2865 		tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1));
2866 		tp->t_flags |= TF_PREVVALID;
2867 	} else
2868 		tp->t_flags &= ~TF_PREVVALID;
2869 	TCPSTAT_INC(tcps_rexmttimeo);
2870 	if ((tp->t_state == TCPS_SYN_SENT) ||
2871 	    (tp->t_state == TCPS_SYN_RECEIVED))
2872 		rexmt = MSEC_2_TICKS(RACK_INITIAL_RTO * tcp_backoff[tp->t_rxtshift]);
2873 	else
2874 		rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
2875 	TCPT_RANGESET(tp->t_rxtcur, rexmt,
2876 	   max(MSEC_2_TICKS(rack_rto_min), rexmt),
2877 	   MSEC_2_TICKS(rack_rto_max));
2878 	/*
2879 	 * We enter the path for PLMTUD if connection is established or, if
2880 	 * connection is FIN_WAIT_1 status, reason for the last is that if
2881 	 * amount of data we send is very small, we could send it in couple
2882 	 * of packets and process straight to FIN. In that case we won't
2883 	 * catch ESTABLISHED state.
2884 	 */
2885 	if (V_tcp_pmtud_blackhole_detect && (((tp->t_state == TCPS_ESTABLISHED))
2886 	    || (tp->t_state == TCPS_FIN_WAIT_1))) {
2887 #ifdef INET6
2888 		int32_t isipv6;
2889 #endif
2890 
2891 		/*
2892 		 * Idea here is that at each stage of mtu probe (usually,
2893 		 * 1448 -> 1188 -> 524) should be given 2 chances to recover
2894 		 * before further clamping down. 'tp->t_rxtshift % 2 == 0'
2895 		 * should take care of that.
2896 		 */
2897 		if (((tp->t_flags2 & (TF2_PLPMTU_PMTUD | TF2_PLPMTU_MAXSEGSNT)) ==
2898 		    (TF2_PLPMTU_PMTUD | TF2_PLPMTU_MAXSEGSNT)) &&
2899 		    (tp->t_rxtshift >= 2 && tp->t_rxtshift < 6 &&
2900 		    tp->t_rxtshift % 2 == 0)) {
2901 			/*
2902 			 * Enter Path MTU Black-hole Detection mechanism: -
2903 			 * Disable Path MTU Discovery (IP "DF" bit). -
2904 			 * Reduce MTU to lower value than what we negotiated
2905 			 * with peer.
2906 			 */
2907 			if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) == 0) {
2908 				/* Record that we may have found a black hole. */
2909 				tp->t_flags2 |= TF2_PLPMTU_BLACKHOLE;
2910 				/* Keep track of previous MSS. */
2911 				tp->t_pmtud_saved_maxseg = tp->t_maxseg;
2912 			}
2913 
2914 			/*
2915 			 * Reduce the MSS to blackhole value or to the
2916 			 * default in an attempt to retransmit.
2917 			 */
2918 #ifdef INET6
2919 			isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) ? 1 : 0;
2920 			if (isipv6 &&
2921 			    tp->t_maxseg > V_tcp_v6pmtud_blackhole_mss) {
2922 				/* Use the sysctl tuneable blackhole MSS. */
2923 				tp->t_maxseg = V_tcp_v6pmtud_blackhole_mss;
2924 				TCPSTAT_INC(tcps_pmtud_blackhole_activated);
2925 			} else if (isipv6) {
2926 				/* Use the default MSS. */
2927 				tp->t_maxseg = V_tcp_v6mssdflt;
2928 				/*
2929 				 * Disable Path MTU Discovery when we switch
2930 				 * to minmss.
2931 				 */
2932 				tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
2933 				TCPSTAT_INC(tcps_pmtud_blackhole_activated_min_mss);
2934 			}
2935 #endif
2936 #if defined(INET6) && defined(INET)
2937 			else
2938 #endif
2939 #ifdef INET
2940 			if (tp->t_maxseg > V_tcp_pmtud_blackhole_mss) {
2941 				/* Use the sysctl tuneable blackhole MSS. */
2942 				tp->t_maxseg = V_tcp_pmtud_blackhole_mss;
2943 				TCPSTAT_INC(tcps_pmtud_blackhole_activated);
2944 			} else {
2945 				/* Use the default MSS. */
2946 				tp->t_maxseg = V_tcp_mssdflt;
2947 				/*
2948 				 * Disable Path MTU Discovery when we switch
2949 				 * to minmss.
2950 				 */
2951 				tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
2952 				TCPSTAT_INC(tcps_pmtud_blackhole_activated_min_mss);
2953 			}
2954 #endif
2955 		} else {
2956 			/*
2957 			 * If further retransmissions are still unsuccessful
2958 			 * with a lowered MTU, maybe this isn't a blackhole
2959 			 * and we restore the previous MSS and blackhole
2960 			 * detection flags. The limit '6' is determined by
2961 			 * giving each probe stage (1448, 1188, 524) 2
2962 			 * chances to recover.
2963 			 */
2964 			if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) &&
2965 			    (tp->t_rxtshift >= 6)) {
2966 				tp->t_flags2 |= TF2_PLPMTU_PMTUD;
2967 				tp->t_flags2 &= ~TF2_PLPMTU_BLACKHOLE;
2968 				tp->t_maxseg = tp->t_pmtud_saved_maxseg;
2969 				TCPSTAT_INC(tcps_pmtud_blackhole_failed);
2970 			}
2971 		}
2972 	}
2973 	/*
2974 	 * Disable RFC1323 and SACK if we haven't got any response to our
2975 	 * third SYN to work-around some broken terminal servers (most of
2976 	 * which have hopefully been retired) that have bad VJ header
2977 	 * compression code which trashes TCP segments containing
2978 	 * unknown-to-them TCP options.
2979 	 */
2980 	if (tcp_rexmit_drop_options && (tp->t_state == TCPS_SYN_SENT) &&
2981 	    (tp->t_rxtshift == 3))
2982 		tp->t_flags &= ~(TF_REQ_SCALE | TF_REQ_TSTMP | TF_SACK_PERMIT);
2983 	/*
2984 	 * If we backed off this far, our srtt estimate is probably bogus.
2985 	 * Clobber it so we'll take the next rtt measurement as our srtt;
2986 	 * move the current srtt into rttvar to keep the current retransmit
2987 	 * times until then.
2988 	 */
2989 	if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) {
2990 #ifdef INET6
2991 		if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0)
2992 			in6_losing(tp->t_inpcb);
2993 		else
2994 #endif
2995 			in_losing(tp->t_inpcb);
2996 		tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT);
2997 		tp->t_srtt = 0;
2998 	}
2999 	if (rack_use_sack_filter)
3000 		sack_filter_clear(&rack->r_ctl.rack_sf, tp->snd_una);
3001 	tp->snd_recover = tp->snd_max;
3002 	tp->t_flags |= TF_ACKNOW;
3003 	tp->t_rtttime = 0;
3004 	rack_cong_signal(tp, NULL, CC_RTO);
3005 out:
3006 	return (retval);
3007 }
3008 
3009 static int
3010 rack_process_timers(struct tcpcb *tp, struct tcp_rack *rack, uint32_t cts, uint8_t hpts_calling)
3011 {
3012 	int32_t ret = 0;
3013 	int32_t timers = (rack->r_ctl.rc_hpts_flags & PACE_TMR_MASK);
3014 
3015 	if (timers == 0) {
3016 		return (0);
3017 	}
3018 	if (tp->t_state == TCPS_LISTEN) {
3019 		/* no timers on listen sockets */
3020 		if (rack->r_ctl.rc_hpts_flags & PACE_PKT_OUTPUT)
3021 			return (0);
3022 		return (1);
3023 	}
3024 	if (TSTMP_LT(cts, rack->r_ctl.rc_timer_exp)) {
3025 		uint32_t left;
3026 
3027 		if (rack->r_ctl.rc_hpts_flags & PACE_PKT_OUTPUT) {
3028 			ret = -1;
3029 			rack_log_to_processing(rack, cts, ret, 0);
3030 			return (0);
3031 		}
3032 		if (hpts_calling == 0) {
3033 			ret = -2;
3034 			rack_log_to_processing(rack, cts, ret, 0);
3035 			return (0);
3036 		}
3037 		/*
3038 		 * Ok our timer went off early and we are not paced false
3039 		 * alarm, go back to sleep.
3040 		 */
3041 		ret = -3;
3042 		left = rack->r_ctl.rc_timer_exp - cts;
3043 		tcp_hpts_insert(tp->t_inpcb, HPTS_MS_TO_SLOTS(left));
3044 		rack_log_to_processing(rack, cts, ret, left);
3045 		rack->rc_last_pto_set = 0;
3046 		return (1);
3047 	}
3048 	rack->rc_tmr_stopped = 0;
3049 	rack->r_ctl.rc_hpts_flags &= ~PACE_TMR_MASK;
3050 	if (timers & PACE_TMR_DELACK) {
3051 		ret = rack_timeout_delack(tp, rack, cts);
3052 	} else if (timers & PACE_TMR_RACK) {
3053 		ret = rack_timeout_rack(tp, rack, cts);
3054 	} else if (timers & PACE_TMR_TLP) {
3055 		ret = rack_timeout_tlp(tp, rack, cts);
3056 	} else if (timers & PACE_TMR_RXT) {
3057 		ret = rack_timeout_rxt(tp, rack, cts);
3058 	} else if (timers & PACE_TMR_PERSIT) {
3059 		ret = rack_timeout_persist(tp, rack, cts);
3060 	} else if (timers & PACE_TMR_KEEP) {
3061 		ret = rack_timeout_keepalive(tp, rack, cts);
3062 	}
3063 	rack_log_to_processing(rack, cts, ret, timers);
3064 	return (ret);
3065 }
3066 
3067 static void
3068 rack_timer_cancel(struct tcpcb *tp, struct tcp_rack *rack, uint32_t cts, int line)
3069 {
3070 	uint8_t hpts_removed = 0;
3071 
3072 	if ((rack->r_ctl.rc_hpts_flags & PACE_PKT_OUTPUT) &&
3073 	    TSTMP_GEQ(cts, rack->r_ctl.rc_last_output_to)) {
3074 		tcp_hpts_remove(rack->rc_inp, HPTS_REMOVE_OUTPUT);
3075 		hpts_removed = 1;
3076 	}
3077 	if (rack->r_ctl.rc_hpts_flags & PACE_TMR_MASK) {
3078 		rack->rc_tmr_stopped = rack->r_ctl.rc_hpts_flags & PACE_TMR_MASK;
3079 		if (rack->rc_inp->inp_in_hpts &&
3080 		    ((rack->r_ctl.rc_hpts_flags & PACE_PKT_OUTPUT) == 0)) {
3081 			/*
3082 			 * Canceling timer's when we have no output being
3083 			 * paced. We also must remove ourselves from the
3084 			 * hpts.
3085 			 */
3086 			tcp_hpts_remove(rack->rc_inp, HPTS_REMOVE_OUTPUT);
3087 			hpts_removed = 1;
3088 		}
3089 		rack_log_to_cancel(rack, hpts_removed, line);
3090 		rack->r_ctl.rc_hpts_flags &= ~(PACE_TMR_MASK);
3091 	}
3092 }
3093 
3094 static void
3095 rack_timer_stop(struct tcpcb *tp, uint32_t timer_type)
3096 {
3097 	return;
3098 }
3099 
3100 static int
3101 rack_stopall(struct tcpcb *tp)
3102 {
3103 	struct tcp_rack *rack;
3104 	rack = (struct tcp_rack *)tp->t_fb_ptr;
3105 	rack->t_timers_stopped = 1;
3106 	return (0);
3107 }
3108 
3109 static void
3110 rack_timer_activate(struct tcpcb *tp, uint32_t timer_type, uint32_t delta)
3111 {
3112 	return;
3113 }
3114 
3115 static int
3116 rack_timer_active(struct tcpcb *tp, uint32_t timer_type)
3117 {
3118 	return (0);
3119 }
3120 
3121 static void
3122 rack_stop_all_timers(struct tcpcb *tp)
3123 {
3124 	struct tcp_rack *rack;
3125 
3126 	/*
3127 	 * Assure no timers are running.
3128 	 */
3129 	if (tcp_timer_active(tp, TT_PERSIST)) {
3130 		/* We enter in persists, set the flag appropriately */
3131 		rack = (struct tcp_rack *)tp->t_fb_ptr;
3132 		rack->rc_in_persist = 1;
3133 	}
3134 	tcp_timer_suspend(tp, TT_PERSIST);
3135 	tcp_timer_suspend(tp, TT_REXMT);
3136 	tcp_timer_suspend(tp, TT_KEEP);
3137 	tcp_timer_suspend(tp, TT_DELACK);
3138 }
3139 
3140 static void
3141 rack_update_rsm(struct tcpcb *tp, struct tcp_rack *rack,
3142     struct rack_sendmap *rsm, uint32_t ts)
3143 {
3144 	int32_t idx;
3145 
3146 	rsm->r_rtr_cnt++;
3147 	rsm->r_sndcnt++;
3148 	if (rsm->r_rtr_cnt > RACK_NUM_OF_RETRANS) {
3149 		rsm->r_rtr_cnt = RACK_NUM_OF_RETRANS;
3150 		rsm->r_flags |= RACK_OVERMAX;
3151 	}
3152 	if ((rsm->r_rtr_cnt > 1) && (rack->r_tlp_running == 0)) {
3153 		rack->r_ctl.rc_holes_rxt += (rsm->r_end - rsm->r_start);
3154 		rsm->r_rtr_bytes += (rsm->r_end - rsm->r_start);
3155 	}
3156 	idx = rsm->r_rtr_cnt - 1;
3157 	rsm->r_tim_lastsent[idx] = ts;
3158 	if (rsm->r_flags & RACK_ACKED) {
3159 		/* Problably MTU discovery messing with us */
3160 		rsm->r_flags &= ~RACK_ACKED;
3161 		rack->r_ctl.rc_sacked -= (rsm->r_end - rsm->r_start);
3162 	}
3163 	if (rsm->r_in_tmap) {
3164 		TAILQ_REMOVE(&rack->r_ctl.rc_tmap, rsm, r_tnext);
3165 	}
3166 	TAILQ_INSERT_TAIL(&rack->r_ctl.rc_tmap, rsm, r_tnext);
3167 	rsm->r_in_tmap = 1;
3168 	if (rsm->r_flags & RACK_SACK_PASSED) {
3169 		/* We have retransmitted due to the SACK pass */
3170 		rsm->r_flags &= ~RACK_SACK_PASSED;
3171 		rsm->r_flags |= RACK_WAS_SACKPASS;
3172 	}
3173 	/* Update memory for next rtr */
3174 	rack->r_ctl.rc_next = TAILQ_NEXT(rsm, r_next);
3175 }
3176 
3177 
3178 static uint32_t
3179 rack_update_entry(struct tcpcb *tp, struct tcp_rack *rack,
3180     struct rack_sendmap *rsm, uint32_t ts, int32_t * lenp)
3181 {
3182 	/*
3183 	 * We (re-)transmitted starting at rsm->r_start for some length
3184 	 * (possibly less than r_end.
3185 	 */
3186 	struct rack_sendmap *nrsm;
3187 	uint32_t c_end;
3188 	int32_t len;
3189 	int32_t idx;
3190 
3191 	len = *lenp;
3192 	c_end = rsm->r_start + len;
3193 	if (SEQ_GEQ(c_end, rsm->r_end)) {
3194 		/*
3195 		 * We retransmitted the whole piece or more than the whole
3196 		 * slopping into the next rsm.
3197 		 */
3198 		rack_update_rsm(tp, rack, rsm, ts);
3199 		if (c_end == rsm->r_end) {
3200 			*lenp = 0;
3201 			return (0);
3202 		} else {
3203 			int32_t act_len;
3204 
3205 			/* Hangs over the end return whats left */
3206 			act_len = rsm->r_end - rsm->r_start;
3207 			*lenp = (len - act_len);
3208 			return (rsm->r_end);
3209 		}
3210 		/* We don't get out of this block. */
3211 	}
3212 	/*
3213 	 * Here we retransmitted less than the whole thing which means we
3214 	 * have to split this into what was transmitted and what was not.
3215 	 */
3216 	nrsm = rack_alloc(rack);
3217 	if (nrsm == NULL) {
3218 		/*
3219 		 * We can't get memory, so lets not proceed.
3220 		 */
3221 		*lenp = 0;
3222 		return (0);
3223 	}
3224 	/*
3225 	 * So here we are going to take the original rsm and make it what we
3226 	 * retransmitted. nrsm will be the tail portion we did not
3227 	 * retransmit. For example say the chunk was 1, 11 (10 bytes). And
3228 	 * we retransmitted 5 bytes i.e. 1, 5. The original piece shrinks to
3229 	 * 1, 6 and the new piece will be 6, 11.
3230 	 */
3231 	nrsm->r_start = c_end;
3232 	nrsm->r_end = rsm->r_end;
3233 	nrsm->r_rtr_cnt = rsm->r_rtr_cnt;
3234 	nrsm->r_flags = rsm->r_flags;
3235 	nrsm->r_sndcnt = rsm->r_sndcnt;
3236 	nrsm->r_rtr_bytes = 0;
3237 	rsm->r_end = c_end;
3238 	for (idx = 0; idx < nrsm->r_rtr_cnt; idx++) {
3239 		nrsm->r_tim_lastsent[idx] = rsm->r_tim_lastsent[idx];
3240 	}
3241 	TAILQ_INSERT_AFTER(&rack->r_ctl.rc_map, rsm, nrsm, r_next);
3242 	if (rsm->r_in_tmap) {
3243 		TAILQ_INSERT_AFTER(&rack->r_ctl.rc_tmap, rsm, nrsm, r_tnext);
3244 		nrsm->r_in_tmap = 1;
3245 	}
3246 	rsm->r_flags &= (~RACK_HAS_FIN);
3247 	rack_update_rsm(tp, rack, rsm, ts);
3248 	*lenp = 0;
3249 	return (0);
3250 }
3251 
3252 
3253 static void
3254 rack_log_output(struct tcpcb *tp, struct tcpopt *to, int32_t len,
3255     uint32_t seq_out, uint8_t th_flags, int32_t err, uint32_t ts,
3256     uint8_t pass, struct rack_sendmap *hintrsm)
3257 {
3258 	struct tcp_rack *rack;
3259 	struct rack_sendmap *rsm, *nrsm;
3260 	register uint32_t snd_max, snd_una;
3261 	int32_t idx;
3262 
3263 	/*
3264 	 * Add to the RACK log of packets in flight or retransmitted. If
3265 	 * there is a TS option we will use the TS echoed, if not we will
3266 	 * grab a TS.
3267 	 *
3268 	 * Retransmissions will increment the count and move the ts to its
3269 	 * proper place. Note that if options do not include TS's then we
3270 	 * won't be able to effectively use the ACK for an RTT on a retran.
3271 	 *
3272 	 * Notes about r_start and r_end. Lets consider a send starting at
3273 	 * sequence 1 for 10 bytes. In such an example the r_start would be
3274 	 * 1 (starting sequence) but the r_end would be r_start+len i.e. 11.
3275 	 * This means that r_end is actually the first sequence for the next
3276 	 * slot (11).
3277 	 *
3278 	 */
3279 	/*
3280 	 * If err is set what do we do XXXrrs? should we not add the thing?
3281 	 * -- i.e. return if err != 0 or should we pretend we sent it? --
3282 	 * i.e. proceed with add ** do this for now.
3283 	 */
3284 	INP_WLOCK_ASSERT(tp->t_inpcb);
3285 	if (err)
3286 		/*
3287 		 * We don't log errors -- we could but snd_max does not
3288 		 * advance in this case either.
3289 		 */
3290 		return;
3291 
3292 	if (th_flags & TH_RST) {
3293 		/*
3294 		 * We don't log resets and we return immediately from
3295 		 * sending
3296 		 */
3297 		return;
3298 	}
3299 	rack = (struct tcp_rack *)tp->t_fb_ptr;
3300 	snd_una = tp->snd_una;
3301 	if (SEQ_LEQ((seq_out + len), snd_una)) {
3302 		/* Are sending an old segment to induce an ack (keep-alive)? */
3303 		return;
3304 	}
3305 	if (SEQ_LT(seq_out, snd_una)) {
3306 		/* huh? should we panic? */
3307 		uint32_t end;
3308 
3309 		end = seq_out + len;
3310 		seq_out = snd_una;
3311 		len = end - seq_out;
3312 	}
3313 	snd_max = tp->snd_max;
3314 	if (th_flags & (TH_SYN | TH_FIN)) {
3315 		/*
3316 		 * The call to rack_log_output is made before bumping
3317 		 * snd_max. This means we can record one extra byte on a SYN
3318 		 * or FIN if seq_out is adding more on and a FIN is present
3319 		 * (and we are not resending).
3320 		 */
3321 		if (th_flags & TH_SYN)
3322 			len++;
3323 		if (th_flags & TH_FIN)
3324 			len++;
3325 		if (SEQ_LT(snd_max, tp->snd_nxt)) {
3326 			/*
3327 			 * The add/update as not been done for the FIN/SYN
3328 			 * yet.
3329 			 */
3330 			snd_max = tp->snd_nxt;
3331 		}
3332 	}
3333 	if (len == 0) {
3334 		/* We don't log zero window probes */
3335 		return;
3336 	}
3337 	rack->r_ctl.rc_time_last_sent = ts;
3338 	if (IN_RECOVERY(tp->t_flags)) {
3339 		rack->r_ctl.rc_prr_out += len;
3340 	}
3341 	/* First question is it a retransmission? */
3342 	if (seq_out == snd_max) {
3343 again:
3344 		rsm = rack_alloc(rack);
3345 		if (rsm == NULL) {
3346 			/*
3347 			 * Hmm out of memory and the tcb got destroyed while
3348 			 * we tried to wait.
3349 			 */
3350 #ifdef INVARIANTS
3351 			panic("Out of memory when we should not be rack:%p", rack);
3352 #endif
3353 			return;
3354 		}
3355 		if (th_flags & TH_FIN) {
3356 			rsm->r_flags = RACK_HAS_FIN;
3357 		} else {
3358 			rsm->r_flags = 0;
3359 		}
3360 		rsm->r_tim_lastsent[0] = ts;
3361 		rsm->r_rtr_cnt = 1;
3362 		rsm->r_rtr_bytes = 0;
3363 		if (th_flags & TH_SYN) {
3364 			/* The data space is one beyond snd_una */
3365 			rsm->r_start = seq_out + 1;
3366 			rsm->r_end = rsm->r_start + (len - 1);
3367 		} else {
3368 			/* Normal case */
3369 			rsm->r_start = seq_out;
3370 			rsm->r_end = rsm->r_start + len;
3371 		}
3372 		rsm->r_sndcnt = 0;
3373 		TAILQ_INSERT_TAIL(&rack->r_ctl.rc_map, rsm, r_next);
3374 		TAILQ_INSERT_TAIL(&rack->r_ctl.rc_tmap, rsm, r_tnext);
3375 		rsm->r_in_tmap = 1;
3376 		return;
3377 	}
3378 	/*
3379 	 * If we reach here its a retransmission and we need to find it.
3380 	 */
3381 more:
3382 	if (hintrsm && (hintrsm->r_start == seq_out)) {
3383 		rsm = hintrsm;
3384 		hintrsm = NULL;
3385 	} else if (rack->r_ctl.rc_next) {
3386 		/* We have a hint from a previous run */
3387 		rsm = rack->r_ctl.rc_next;
3388 	} else {
3389 		/* No hints sorry */
3390 		rsm = NULL;
3391 	}
3392 	if ((rsm) && (rsm->r_start == seq_out)) {
3393 		/*
3394 		 * We used rc_next or hintrsm  to retransmit, hopefully the
3395 		 * likely case.
3396 		 */
3397 		seq_out = rack_update_entry(tp, rack, rsm, ts, &len);
3398 		if (len == 0) {
3399 			return;
3400 		} else {
3401 			goto more;
3402 		}
3403 	}
3404 	/* Ok it was not the last pointer go through it the hard way. */
3405 	TAILQ_FOREACH(rsm, &rack->r_ctl.rc_map, r_next) {
3406 		if (rsm->r_start == seq_out) {
3407 			seq_out = rack_update_entry(tp, rack, rsm, ts, &len);
3408 			rack->r_ctl.rc_next = TAILQ_NEXT(rsm, r_next);
3409 			if (len == 0) {
3410 				return;
3411 			} else {
3412 				continue;
3413 			}
3414 		}
3415 		if (SEQ_GEQ(seq_out, rsm->r_start) && SEQ_LT(seq_out, rsm->r_end)) {
3416 			/* Transmitted within this piece */
3417 			/*
3418 			 * Ok we must split off the front and then let the
3419 			 * update do the rest
3420 			 */
3421 			nrsm = rack_alloc(rack);
3422 			if (nrsm == NULL) {
3423 #ifdef INVARIANTS
3424 				panic("Ran out of memory that was preallocated? rack:%p", rack);
3425 #endif
3426 				rack_update_rsm(tp, rack, rsm, ts);
3427 				return;
3428 			}
3429 			/*
3430 			 * copy rsm to nrsm and then trim the front of rsm
3431 			 * to not include this part.
3432 			 */
3433 			nrsm->r_start = seq_out;
3434 			nrsm->r_end = rsm->r_end;
3435 			nrsm->r_rtr_cnt = rsm->r_rtr_cnt;
3436 			nrsm->r_flags = rsm->r_flags;
3437 			nrsm->r_sndcnt = rsm->r_sndcnt;
3438 			nrsm->r_rtr_bytes = 0;
3439 			for (idx = 0; idx < nrsm->r_rtr_cnt; idx++) {
3440 				nrsm->r_tim_lastsent[idx] = rsm->r_tim_lastsent[idx];
3441 			}
3442 			rsm->r_end = nrsm->r_start;
3443 			TAILQ_INSERT_AFTER(&rack->r_ctl.rc_map, rsm, nrsm, r_next);
3444 			if (rsm->r_in_tmap) {
3445 				TAILQ_INSERT_AFTER(&rack->r_ctl.rc_tmap, rsm, nrsm, r_tnext);
3446 				nrsm->r_in_tmap = 1;
3447 			}
3448 			rsm->r_flags &= (~RACK_HAS_FIN);
3449 			seq_out = rack_update_entry(tp, rack, nrsm, ts, &len);
3450 			if (len == 0) {
3451 				return;
3452 			}
3453 		}
3454 	}
3455 	/*
3456 	 * Hmm not found in map did they retransmit both old and on into the
3457 	 * new?
3458 	 */
3459 	if (seq_out == tp->snd_max) {
3460 		goto again;
3461 	} else if (SEQ_LT(seq_out, tp->snd_max)) {
3462 #ifdef INVARIANTS
3463 		printf("seq_out:%u len:%d snd_una:%u snd_max:%u -- but rsm not found?\n",
3464 		    seq_out, len, tp->snd_una, tp->snd_max);
3465 		printf("Starting Dump of all rack entries\n");
3466 		TAILQ_FOREACH(rsm, &rack->r_ctl.rc_map, r_next) {
3467 			printf("rsm:%p start:%u end:%u\n",
3468 			    rsm, rsm->r_start, rsm->r_end);
3469 		}
3470 		printf("Dump complete\n");
3471 		panic("seq_out not found rack:%p tp:%p",
3472 		    rack, tp);
3473 #endif
3474 	} else {
3475 #ifdef INVARIANTS
3476 		/*
3477 		 * Hmm beyond sndmax? (only if we are using the new rtt-pack
3478 		 * flag)
3479 		 */
3480 		panic("seq_out:%u(%d) is beyond snd_max:%u tp:%p",
3481 		    seq_out, len, tp->snd_max, tp);
3482 #endif
3483 	}
3484 }
3485 
3486 /*
3487  * Record one of the RTT updates from an ack into
3488  * our sample structure.
3489  */
3490 static void
3491 tcp_rack_xmit_timer(struct tcp_rack *rack, int32_t rtt)
3492 {
3493 	if ((rack->r_ctl.rack_rs.rs_flags & RACK_RTT_EMPTY) ||
3494 	    (rack->r_ctl.rack_rs.rs_rtt_lowest > rtt)) {
3495 		rack->r_ctl.rack_rs.rs_rtt_lowest = rtt;
3496 	}
3497 	if ((rack->r_ctl.rack_rs.rs_flags & RACK_RTT_EMPTY) ||
3498 	    (rack->r_ctl.rack_rs.rs_rtt_highest < rtt)) {
3499 		rack->r_ctl.rack_rs.rs_rtt_highest = rtt;
3500 	}
3501 	rack->r_ctl.rack_rs.rs_flags = RACK_RTT_VALID;
3502 	rack->r_ctl.rack_rs.rs_rtt_tot += rtt;
3503 	rack->r_ctl.rack_rs.rs_rtt_cnt++;
3504 }
3505 
3506 /*
3507  * Collect new round-trip time estimate
3508  * and update averages and current timeout.
3509  */
3510 static void
3511 tcp_rack_xmit_timer_commit(struct tcp_rack *rack, struct tcpcb *tp)
3512 {
3513 	int32_t delta;
3514 	uint32_t o_srtt, o_var;
3515 	int32_t rtt;
3516 
3517 	if (rack->r_ctl.rack_rs.rs_flags & RACK_RTT_EMPTY)
3518 		/* No valid sample */
3519 		return;
3520 	if (rack->r_ctl.rc_rate_sample_method == USE_RTT_LOW) {
3521 		/* We are to use the lowest RTT seen in a single ack */
3522 		rtt = rack->r_ctl.rack_rs.rs_rtt_lowest;
3523 	} else if (rack->r_ctl.rc_rate_sample_method == USE_RTT_HIGH) {
3524 		/* We are to use the highest RTT seen in a single ack */
3525 		rtt = rack->r_ctl.rack_rs.rs_rtt_highest;
3526 	} else if (rack->r_ctl.rc_rate_sample_method == USE_RTT_AVG) {
3527 		/* We are to use the average RTT seen in a single ack */
3528 		rtt = (int32_t)(rack->r_ctl.rack_rs.rs_rtt_tot /
3529 				(uint64_t)rack->r_ctl.rack_rs.rs_rtt_cnt);
3530 	} else {
3531 #ifdef INVARIANTS
3532 		panic("Unknown rtt variant %d", rack->r_ctl.rc_rate_sample_method);
3533 #endif
3534 		return;
3535 	}
3536 	if (rtt == 0)
3537 		rtt = 1;
3538 	rack_log_rtt_sample(rack, rtt);
3539 	o_srtt = tp->t_srtt;
3540 	o_var = tp->t_rttvar;
3541 	rack = (struct tcp_rack *)tp->t_fb_ptr;
3542 	if (tp->t_srtt != 0) {
3543 		/*
3544 		 * srtt is stored as fixed point with 5 bits after the
3545 		 * binary point (i.e., scaled by 8).  The following magic is
3546 		 * equivalent to the smoothing algorithm in rfc793 with an
3547 		 * alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed point).
3548 		 * Adjust rtt to origin 0.
3549 		 */
3550 		delta = ((rtt - 1) << TCP_DELTA_SHIFT)
3551 		    - (tp->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT));
3552 
3553 		tp->t_srtt += delta;
3554 		if (tp->t_srtt <= 0)
3555 			tp->t_srtt = 1;
3556 
3557 		/*
3558 		 * We accumulate a smoothed rtt variance (actually, a
3559 		 * smoothed mean difference), then set the retransmit timer
3560 		 * to smoothed rtt + 4 times the smoothed variance. rttvar
3561 		 * is stored as fixed point with 4 bits after the binary
3562 		 * point (scaled by 16).  The following is equivalent to
3563 		 * rfc793 smoothing with an alpha of .75 (rttvar =
3564 		 * rttvar*3/4 + |delta| / 4).  This replaces rfc793's
3565 		 * wired-in beta.
3566 		 */
3567 		if (delta < 0)
3568 			delta = -delta;
3569 		delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT);
3570 		tp->t_rttvar += delta;
3571 		if (tp->t_rttvar <= 0)
3572 			tp->t_rttvar = 1;
3573 		if (tp->t_rttbest > tp->t_srtt + tp->t_rttvar)
3574 			tp->t_rttbest = tp->t_srtt + tp->t_rttvar;
3575 	} else {
3576 		/*
3577 		 * No rtt measurement yet - use the unsmoothed rtt. Set the
3578 		 * variance to half the rtt (so our first retransmit happens
3579 		 * at 3*rtt).
3580 		 */
3581 		tp->t_srtt = rtt << TCP_RTT_SHIFT;
3582 		tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1);
3583 		tp->t_rttbest = tp->t_srtt + tp->t_rttvar;
3584 	}
3585 	TCPSTAT_INC(tcps_rttupdated);
3586 	rack_log_rtt_upd(tp, rack, rtt, o_srtt, o_var);
3587 	tp->t_rttupdated++;
3588 #ifdef NETFLIX_STATS
3589 	stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_RTT, imax(0, rtt));
3590 #endif
3591 	tp->t_rxtshift = 0;
3592 
3593 	/*
3594 	 * the retransmit should happen at rtt + 4 * rttvar. Because of the
3595 	 * way we do the smoothing, srtt and rttvar will each average +1/2
3596 	 * tick of bias.  When we compute the retransmit timer, we want 1/2
3597 	 * tick of rounding and 1 extra tick because of +-1/2 tick
3598 	 * uncertainty in the firing of the timer.  The bias will give us
3599 	 * exactly the 1.5 tick we need.  But, because the bias is
3600 	 * statistical, we have to test that we don't drop below the minimum
3601 	 * feasible timer (which is 2 ticks).
3602 	 */
3603 	TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp),
3604 	   max(MSEC_2_TICKS(rack_rto_min), rtt + 2), MSEC_2_TICKS(rack_rto_max));
3605 	tp->t_softerror = 0;
3606 }
3607 
3608 static void
3609 rack_earlier_retran(struct tcpcb *tp, struct rack_sendmap *rsm,
3610     uint32_t t, uint32_t cts)
3611 {
3612 	/*
3613 	 * For this RSM, we acknowledged the data from a previous
3614 	 * transmission, not the last one we made. This means we did a false
3615 	 * retransmit.
3616 	 */
3617 	struct tcp_rack *rack;
3618 
3619 	if (rsm->r_flags & RACK_HAS_FIN) {
3620 		/*
3621 		 * The sending of the FIN often is multiple sent when we
3622 		 * have everything outstanding ack'd. We ignore this case
3623 		 * since its over now.
3624 		 */
3625 		return;
3626 	}
3627 	if (rsm->r_flags & RACK_TLP) {
3628 		/*
3629 		 * We expect TLP's to have this occur.
3630 		 */
3631 		return;
3632 	}
3633 	rack = (struct tcp_rack *)tp->t_fb_ptr;
3634 	/* should we undo cc changes and exit recovery? */
3635 	if (IN_RECOVERY(tp->t_flags)) {
3636 		if (rack->r_ctl.rc_rsm_start == rsm->r_start) {
3637 			/*
3638 			 * Undo what we ratched down and exit recovery if
3639 			 * possible
3640 			 */
3641 			EXIT_RECOVERY(tp->t_flags);
3642 			tp->snd_recover = tp->snd_una;
3643 			if (rack->r_ctl.rc_cwnd_at > tp->snd_cwnd)
3644 				tp->snd_cwnd = rack->r_ctl.rc_cwnd_at;
3645 			if (rack->r_ctl.rc_ssthresh_at > tp->snd_ssthresh)
3646 				tp->snd_ssthresh = rack->r_ctl.rc_ssthresh_at;
3647 		}
3648 	}
3649 	if (rsm->r_flags & RACK_WAS_SACKPASS) {
3650 		/*
3651 		 * We retransmitted based on a sack and the earlier
3652 		 * retransmission ack'd it - re-ordering is occuring.
3653 		 */
3654 		counter_u64_add(rack_reorder_seen, 1);
3655 		rack->r_ctl.rc_reorder_ts = cts;
3656 	}
3657 	counter_u64_add(rack_badfr, 1);
3658 	counter_u64_add(rack_badfr_bytes, (rsm->r_end - rsm->r_start));
3659 }
3660 
3661 
3662 static int
3663 rack_update_rtt(struct tcpcb *tp, struct tcp_rack *rack,
3664     struct rack_sendmap *rsm, struct tcpopt *to, uint32_t cts, int32_t ack_type)
3665 {
3666 	int32_t i;
3667 	uint32_t t;
3668 
3669 	if (rsm->r_flags & RACK_ACKED)
3670 		/* Already done */
3671 		return (0);
3672 
3673 
3674 	if ((rsm->r_rtr_cnt == 1) ||
3675 	    ((ack_type == CUM_ACKED) &&
3676 	    (to->to_flags & TOF_TS) &&
3677 	    (to->to_tsecr) &&
3678 	    (rsm->r_tim_lastsent[rsm->r_rtr_cnt - 1] == to->to_tsecr))
3679 	    ) {
3680 		/*
3681 		 * We will only find a matching timestamp if its cum-acked.
3682 		 * But if its only one retransmission its for-sure matching
3683 		 * :-)
3684 		 */
3685 		t = cts - rsm->r_tim_lastsent[(rsm->r_rtr_cnt - 1)];
3686 		if ((int)t <= 0)
3687 			t = 1;
3688 		if (!tp->t_rttlow || tp->t_rttlow > t)
3689 			tp->t_rttlow = t;
3690 		if (!rack->r_ctl.rc_rack_min_rtt ||
3691 		    SEQ_LT(t, rack->r_ctl.rc_rack_min_rtt)) {
3692 			rack->r_ctl.rc_rack_min_rtt = t;
3693 			if (rack->r_ctl.rc_rack_min_rtt == 0) {
3694 				rack->r_ctl.rc_rack_min_rtt = 1;
3695 			}
3696 		}
3697 		tcp_rack_xmit_timer(rack, TCP_TS_TO_TICKS(t) + 1);
3698 		if ((rsm->r_flags & RACK_TLP) &&
3699 		    (!IN_RECOVERY(tp->t_flags))) {
3700 			/* Segment was a TLP and our retrans matched */
3701 			if (rack->r_ctl.rc_tlp_cwnd_reduce) {
3702 				rack->r_ctl.rc_rsm_start = tp->snd_max;
3703 				rack->r_ctl.rc_cwnd_at = tp->snd_cwnd;
3704 				rack->r_ctl.rc_ssthresh_at = tp->snd_ssthresh;
3705 				rack_cong_signal(tp, NULL, CC_NDUPACK);
3706 				/*
3707 				 * When we enter recovery we need to assure
3708 				 * we send one packet.
3709 				 */
3710 				rack->r_ctl.rc_prr_sndcnt = tp->t_maxseg;
3711 			} else
3712 				rack->r_ctl.rc_tlp_rtx_out = 0;
3713 		}
3714 		if (SEQ_LT(rack->r_ctl.rc_rack_tmit_time, rsm->r_tim_lastsent[(rsm->r_rtr_cnt - 1)])) {
3715 			/* New more recent rack_tmit_time */
3716 			rack->r_ctl.rc_rack_tmit_time = rsm->r_tim_lastsent[(rsm->r_rtr_cnt - 1)];
3717 			rack->rc_rack_rtt = t;
3718 		}
3719 		return (1);
3720 	}
3721 	/*
3722 	 * We clear the soft/rxtshift since we got an ack.
3723 	 * There is no assurance we will call the commit() function
3724 	 * so we need to clear these to avoid incorrect handling.
3725 	 */
3726 	tp->t_rxtshift = 0;
3727 	tp->t_softerror = 0;
3728 	if ((to->to_flags & TOF_TS) &&
3729 	    (ack_type == CUM_ACKED) &&
3730 	    (to->to_tsecr) &&
3731 	    ((rsm->r_flags & (RACK_DEFERRED | RACK_OVERMAX)) == 0)) {
3732 		/*
3733 		 * Now which timestamp does it match? In this block the ACK
3734 		 * must be coming from a previous transmission.
3735 		 */
3736 		for (i = 0; i < rsm->r_rtr_cnt; i++) {
3737 			if (rsm->r_tim_lastsent[i] == to->to_tsecr) {
3738 				t = cts - rsm->r_tim_lastsent[i];
3739 				if ((int)t <= 0)
3740 					t = 1;
3741 				if ((i + 1) < rsm->r_rtr_cnt) {
3742 					/* Likely */
3743 					rack_earlier_retran(tp, rsm, t, cts);
3744 				}
3745 				if (!tp->t_rttlow || tp->t_rttlow > t)
3746 					tp->t_rttlow = t;
3747 				if (!rack->r_ctl.rc_rack_min_rtt || SEQ_LT(t, rack->r_ctl.rc_rack_min_rtt)) {
3748 					rack->r_ctl.rc_rack_min_rtt = t;
3749 					if (rack->r_ctl.rc_rack_min_rtt == 0) {
3750 						rack->r_ctl.rc_rack_min_rtt = 1;
3751 					}
3752 				}
3753                                 /*
3754 				 * Note the following calls to
3755 				 * tcp_rack_xmit_timer() are being commented
3756 				 * out for now. They give us no more accuracy
3757 				 * and often lead to a wrong choice. We have
3758 				 * enough samples that have not been
3759 				 * retransmitted. I leave the commented out
3760 				 * code in here in case in the future we
3761 				 * decide to add it back (though I can't forsee
3762 				 * doing that). That way we will easily see
3763 				 * where they need to be placed.
3764 				 */
3765 				if (SEQ_LT(rack->r_ctl.rc_rack_tmit_time,
3766 				    rsm->r_tim_lastsent[(rsm->r_rtr_cnt - 1)])) {
3767 					/* New more recent rack_tmit_time */
3768 					rack->r_ctl.rc_rack_tmit_time = rsm->r_tim_lastsent[(rsm->r_rtr_cnt - 1)];
3769 					rack->rc_rack_rtt = t;
3770 				}
3771 				return (1);
3772 			}
3773 		}
3774 		goto ts_not_found;
3775 	} else {
3776 		/*
3777 		 * Ok its a SACK block that we retransmitted. or a windows
3778 		 * machine without timestamps. We can tell nothing from the
3779 		 * time-stamp since its not there or the time the peer last
3780 		 * recieved a segment that moved forward its cum-ack point.
3781 		 */
3782 ts_not_found:
3783 		i = rsm->r_rtr_cnt - 1;
3784 		t = cts - rsm->r_tim_lastsent[i];
3785 		if ((int)t <= 0)
3786 			t = 1;
3787 		if (rack->r_ctl.rc_rack_min_rtt && SEQ_LT(t, rack->r_ctl.rc_rack_min_rtt)) {
3788 			/*
3789 			 * We retransmitted and the ack came back in less
3790 			 * than the smallest rtt we have observed. We most
3791 			 * likey did an improper retransmit as outlined in
3792 			 * 4.2 Step 3 point 2 in the rack-draft.
3793 			 */
3794 			i = rsm->r_rtr_cnt - 2;
3795 			t = cts - rsm->r_tim_lastsent[i];
3796 			rack_earlier_retran(tp, rsm, t, cts);
3797 		} else if (rack->r_ctl.rc_rack_min_rtt) {
3798 			/*
3799 			 * We retransmitted it and the retransmit did the
3800 			 * job.
3801 			 */
3802 			if (!rack->r_ctl.rc_rack_min_rtt ||
3803 			    SEQ_LT(t, rack->r_ctl.rc_rack_min_rtt)) {
3804 				rack->r_ctl.rc_rack_min_rtt = t;
3805 				if (rack->r_ctl.rc_rack_min_rtt == 0) {
3806 					rack->r_ctl.rc_rack_min_rtt = 1;
3807 				}
3808 			}
3809 			if (SEQ_LT(rack->r_ctl.rc_rack_tmit_time, rsm->r_tim_lastsent[i])) {
3810 				/* New more recent rack_tmit_time */
3811 				rack->r_ctl.rc_rack_tmit_time = rsm->r_tim_lastsent[i];
3812 				rack->rc_rack_rtt = t;
3813 			}
3814 			return (1);
3815 		}
3816 	}
3817 	return (0);
3818 }
3819 
3820 /*
3821  * Mark the SACK_PASSED flag on all entries prior to rsm send wise.
3822  */
3823 static void
3824 rack_log_sack_passed(struct tcpcb *tp,
3825     struct tcp_rack *rack, struct rack_sendmap *rsm)
3826 {
3827 	struct rack_sendmap *nrsm;
3828 	uint32_t ts;
3829 	int32_t idx;
3830 
3831 	idx = rsm->r_rtr_cnt - 1;
3832 	ts = rsm->r_tim_lastsent[idx];
3833 	nrsm = rsm;
3834 	TAILQ_FOREACH_REVERSE_FROM(nrsm, &rack->r_ctl.rc_tmap,
3835 	    rack_head, r_tnext) {
3836 		if (nrsm == rsm) {
3837 			/* Skip orginal segment he is acked */
3838 			continue;
3839 		}
3840 		if (nrsm->r_flags & RACK_ACKED) {
3841 			/* Skip ack'd segments */
3842 			continue;
3843 		}
3844 		idx = nrsm->r_rtr_cnt - 1;
3845 		if (ts == nrsm->r_tim_lastsent[idx]) {
3846 			/*
3847 			 * For this case lets use seq no, if we sent in a
3848 			 * big block (TSO) we would have a bunch of segments
3849 			 * sent at the same time.
3850 			 *
3851 			 * We would only get a report if its SEQ is earlier.
3852 			 * If we have done multiple retransmits the times
3853 			 * would not be equal.
3854 			 */
3855 			if (SEQ_LT(nrsm->r_start, rsm->r_start)) {
3856 				nrsm->r_flags |= RACK_SACK_PASSED;
3857 				nrsm->r_flags &= ~RACK_WAS_SACKPASS;
3858 			}
3859 		} else {
3860 			/*
3861 			 * Here they were sent at different times, not a big
3862 			 * block. Since we transmitted this one later and
3863 			 * see it sack'd then this must also be missing (or
3864 			 * we would have gotten a sack block for it)
3865 			 */
3866 			nrsm->r_flags |= RACK_SACK_PASSED;
3867 			nrsm->r_flags &= ~RACK_WAS_SACKPASS;
3868 		}
3869 	}
3870 }
3871 
3872 static uint32_t
3873 rack_proc_sack_blk(struct tcpcb *tp, struct tcp_rack *rack, struct sackblk *sack,
3874     struct tcpopt *to, struct rack_sendmap **prsm, uint32_t cts)
3875 {
3876 	int32_t idx;
3877 	int32_t times = 0;
3878 	uint32_t start, end, changed = 0;
3879 	struct rack_sendmap *rsm, *nrsm;
3880 	int32_t used_ref = 1;
3881 
3882 	start = sack->start;
3883 	end = sack->end;
3884 	rsm = *prsm;
3885 	if (rsm && SEQ_LT(start, rsm->r_start)) {
3886 		TAILQ_FOREACH_REVERSE_FROM(rsm, &rack->r_ctl.rc_map, rack_head, r_next) {
3887 			if (SEQ_GEQ(start, rsm->r_start) &&
3888 			    SEQ_LT(start, rsm->r_end)) {
3889 				goto do_rest_ofb;
3890 			}
3891 		}
3892 	}
3893 	if (rsm == NULL) {
3894 start_at_beginning:
3895 		rsm = NULL;
3896 		used_ref = 0;
3897 	}
3898 	/* First lets locate the block where this guy is */
3899 	TAILQ_FOREACH_FROM(rsm, &rack->r_ctl.rc_map, r_next) {
3900 		if (SEQ_GEQ(start, rsm->r_start) &&
3901 		    SEQ_LT(start, rsm->r_end)) {
3902 			break;
3903 		}
3904 	}
3905 do_rest_ofb:
3906 	if (rsm == NULL) {
3907 		/*
3908 		 * This happens when we get duplicate sack blocks with the
3909 		 * same end. For example SACK 4: 100 SACK 3: 100 The sort
3910 		 * will not change there location so we would just start at
3911 		 * the end of the first one and get lost.
3912 		 */
3913 		if (tp->t_flags & TF_SENTFIN) {
3914 			/*
3915 			 * Check to see if we have not logged the FIN that
3916 			 * went out.
3917 			 */
3918 			nrsm = TAILQ_LAST_FAST(&rack->r_ctl.rc_map, rack_sendmap, r_next);
3919 			if (nrsm && (nrsm->r_end + 1) == tp->snd_max) {
3920 				/*
3921 				 * Ok we did not get the FIN logged.
3922 				 */
3923 				nrsm->r_end++;
3924 				rsm = nrsm;
3925 				goto do_rest_ofb;
3926 			}
3927 		}
3928 		if (times == 1) {
3929 #ifdef INVARIANTS
3930 			panic("tp:%p rack:%p sack:%p to:%p prsm:%p",
3931 			    tp, rack, sack, to, prsm);
3932 #else
3933 			goto out;
3934 #endif
3935 		}
3936 		times++;
3937 		counter_u64_add(rack_sack_proc_restart, 1);
3938 		goto start_at_beginning;
3939 	}
3940 	/* Ok we have an ACK for some piece of rsm */
3941 	if (rsm->r_start != start) {
3942 		/*
3943 		 * Need to split this in two pieces the before and after.
3944 		 */
3945 		nrsm = rack_alloc(rack);
3946 		if (nrsm == NULL) {
3947 			/*
3948 			 * failed XXXrrs what can we do but loose the sack
3949 			 * info?
3950 			 */
3951 			goto out;
3952 		}
3953 		nrsm->r_start = start;
3954 		nrsm->r_rtr_bytes = 0;
3955 		nrsm->r_end = rsm->r_end;
3956 		nrsm->r_rtr_cnt = rsm->r_rtr_cnt;
3957 		nrsm->r_flags = rsm->r_flags;
3958 		nrsm->r_sndcnt = rsm->r_sndcnt;
3959 		for (idx = 0; idx < nrsm->r_rtr_cnt; idx++) {
3960 			nrsm->r_tim_lastsent[idx] = rsm->r_tim_lastsent[idx];
3961 		}
3962 		rsm->r_end = nrsm->r_start;
3963 		TAILQ_INSERT_AFTER(&rack->r_ctl.rc_map, rsm, nrsm, r_next);
3964 		if (rsm->r_in_tmap) {
3965 			TAILQ_INSERT_AFTER(&rack->r_ctl.rc_tmap, rsm, nrsm, r_tnext);
3966 			nrsm->r_in_tmap = 1;
3967 		}
3968 		rsm->r_flags &= (~RACK_HAS_FIN);
3969 		rsm = nrsm;
3970 	}
3971 	if (SEQ_GEQ(end, rsm->r_end)) {
3972 		/*
3973 		 * The end of this block is either beyond this guy or right
3974 		 * at this guy.
3975 		 */
3976 
3977 		if ((rsm->r_flags & RACK_ACKED) == 0) {
3978 			rack_update_rtt(tp, rack, rsm, to, cts, SACKED);
3979 			changed += (rsm->r_end - rsm->r_start);
3980 			rack->r_ctl.rc_sacked += (rsm->r_end - rsm->r_start);
3981 			rack_log_sack_passed(tp, rack, rsm);
3982 			/* Is Reordering occuring? */
3983 			if (rsm->r_flags & RACK_SACK_PASSED) {
3984 				counter_u64_add(rack_reorder_seen, 1);
3985 				rack->r_ctl.rc_reorder_ts = cts;
3986 			}
3987 			rsm->r_flags |= RACK_ACKED;
3988 			rsm->r_flags &= ~RACK_TLP;
3989 			if (rsm->r_in_tmap) {
3990 				TAILQ_REMOVE(&rack->r_ctl.rc_tmap, rsm, r_tnext);
3991 				rsm->r_in_tmap = 0;
3992 			}
3993 		}
3994 		if (end == rsm->r_end) {
3995 			/* This block only - done */
3996 			goto out;
3997 		}
3998 		/* There is more not coverend by this rsm move on */
3999 		start = rsm->r_end;
4000 		nrsm = TAILQ_NEXT(rsm, r_next);
4001 		rsm = nrsm;
4002 		times = 0;
4003 		goto do_rest_ofb;
4004 	}
4005 	/* Ok we need to split off this one at the tail */
4006 	nrsm = rack_alloc(rack);
4007 	if (nrsm == NULL) {
4008 		/* failed rrs what can we do but loose the sack info? */
4009 		goto out;
4010 	}
4011 	/* Clone it */
4012 	nrsm->r_start = end;
4013 	nrsm->r_end = rsm->r_end;
4014 	nrsm->r_rtr_bytes = 0;
4015 	nrsm->r_rtr_cnt = rsm->r_rtr_cnt;
4016 	nrsm->r_flags = rsm->r_flags;
4017 	nrsm->r_sndcnt = rsm->r_sndcnt;
4018 	for (idx = 0; idx < nrsm->r_rtr_cnt; idx++) {
4019 		nrsm->r_tim_lastsent[idx] = rsm->r_tim_lastsent[idx];
4020 	}
4021 	/* The sack block does not cover this guy fully */
4022 	rsm->r_flags &= (~RACK_HAS_FIN);
4023 	rsm->r_end = end;
4024 	TAILQ_INSERT_AFTER(&rack->r_ctl.rc_map, rsm, nrsm, r_next);
4025 	if (rsm->r_in_tmap) {
4026 		TAILQ_INSERT_AFTER(&rack->r_ctl.rc_tmap, rsm, nrsm, r_tnext);
4027 		nrsm->r_in_tmap = 1;
4028 	}
4029 	if (rsm->r_flags & RACK_ACKED) {
4030 		/* Been here done that */
4031 		goto out;
4032 	}
4033 	rack_update_rtt(tp, rack, rsm, to, cts, SACKED);
4034 	changed += (rsm->r_end - rsm->r_start);
4035 	rack->r_ctl.rc_sacked += (rsm->r_end - rsm->r_start);
4036 	rack_log_sack_passed(tp, rack, rsm);
4037 	/* Is Reordering occuring? */
4038 	if (rsm->r_flags & RACK_SACK_PASSED) {
4039 		counter_u64_add(rack_reorder_seen, 1);
4040 		rack->r_ctl.rc_reorder_ts = cts;
4041 	}
4042 	rsm->r_flags |= RACK_ACKED;
4043 	rsm->r_flags &= ~RACK_TLP;
4044 	if (rsm->r_in_tmap) {
4045 		TAILQ_REMOVE(&rack->r_ctl.rc_tmap, rsm, r_tnext);
4046 		rsm->r_in_tmap = 0;
4047 	}
4048 out:
4049 	if (used_ref == 0) {
4050 		counter_u64_add(rack_sack_proc_all, 1);
4051 	} else {
4052 		counter_u64_add(rack_sack_proc_short, 1);
4053 	}
4054 	/* Save off where we last were */
4055 	if (rsm)
4056 		rack->r_ctl.rc_sacklast = TAILQ_NEXT(rsm, r_next);
4057 	else
4058 		rack->r_ctl.rc_sacklast = NULL;
4059 	*prsm = rsm;
4060 	return (changed);
4061 }
4062 
4063 static void inline
4064 rack_peer_reneges(struct tcp_rack *rack, struct rack_sendmap *rsm, tcp_seq th_ack)
4065 {
4066 	struct rack_sendmap *tmap;
4067 
4068 	tmap = NULL;
4069 	while (rsm && (rsm->r_flags & RACK_ACKED)) {
4070 		/* Its no longer sacked, mark it so */
4071 		rack->r_ctl.rc_sacked -= (rsm->r_end - rsm->r_start);
4072 #ifdef INVARIANTS
4073 		if (rsm->r_in_tmap) {
4074 			panic("rack:%p rsm:%p flags:0x%x in tmap?",
4075 			      rack, rsm, rsm->r_flags);
4076 		}
4077 #endif
4078 		rsm->r_flags &= ~(RACK_ACKED|RACK_SACK_PASSED|RACK_WAS_SACKPASS);
4079 		/* Rebuild it into our tmap */
4080 		if (tmap == NULL) {
4081 			TAILQ_INSERT_HEAD(&rack->r_ctl.rc_tmap, rsm, r_tnext);
4082 			tmap = rsm;
4083 		} else {
4084 			TAILQ_INSERT_AFTER(&rack->r_ctl.rc_tmap, tmap, rsm, r_tnext);
4085 			tmap = rsm;
4086 		}
4087 		tmap->r_in_tmap = 1;
4088 		rsm = TAILQ_NEXT(rsm, r_next);
4089 	}
4090 	/*
4091 	 * Now lets possibly clear the sack filter so we start
4092 	 * recognizing sacks that cover this area.
4093 	 */
4094 	if (rack_use_sack_filter)
4095 		sack_filter_clear(&rack->r_ctl.rack_sf, th_ack);
4096 
4097 }
4098 
4099 static void
4100 rack_log_ack(struct tcpcb *tp, struct tcpopt *to, struct tcphdr *th)
4101 {
4102 	uint32_t changed, last_seq, entered_recovery = 0;
4103 	struct tcp_rack *rack;
4104 	struct rack_sendmap *rsm;
4105 	struct sackblk sack, sack_blocks[TCP_MAX_SACK + 1];
4106 	register uint32_t th_ack;
4107 	int32_t i, j, k, num_sack_blks = 0;
4108 	uint32_t cts, acked, ack_point, sack_changed = 0;
4109 
4110 	INP_WLOCK_ASSERT(tp->t_inpcb);
4111 	if (th->th_flags & TH_RST) {
4112 		/* We don't log resets */
4113 		return;
4114 	}
4115 	rack = (struct tcp_rack *)tp->t_fb_ptr;
4116 	cts = tcp_ts_getticks();
4117 	rsm = TAILQ_FIRST(&rack->r_ctl.rc_map);
4118 	changed = 0;
4119 	th_ack = th->th_ack;
4120 
4121 	if (SEQ_GT(th_ack, tp->snd_una)) {
4122 		rack_log_progress_event(rack, tp, ticks, PROGRESS_UPDATE, __LINE__);
4123 		tp->t_acktime = ticks;
4124 	}
4125 	if (rsm && SEQ_GT(th_ack, rsm->r_start))
4126 		changed = th_ack - rsm->r_start;
4127 	if (changed) {
4128 		/*
4129 		 * The ACK point is advancing to th_ack, we must drop off
4130 		 * the packets in the rack log and calculate any eligble
4131 		 * RTT's.
4132 		 */
4133 		rack->r_wanted_output++;
4134 more:
4135 		rsm = TAILQ_FIRST(&rack->r_ctl.rc_map);
4136 		if (rsm == NULL) {
4137 			if ((th_ack - 1) == tp->iss) {
4138 				/*
4139 				 * For the SYN incoming case we will not
4140 				 * have called tcp_output for the sending of
4141 				 * the SYN, so there will be no map. All
4142 				 * other cases should probably be a panic.
4143 				 */
4144 				goto proc_sack;
4145 			}
4146 			if (tp->t_flags & TF_SENTFIN) {
4147 				/* if we send a FIN we will not hav a map */
4148 				goto proc_sack;
4149 			}
4150 #ifdef INVARIANTS
4151 			panic("No rack map tp:%p for th:%p state:%d rack:%p snd_una:%u snd_max:%u snd_nxt:%u chg:%d\n",
4152 			    tp,
4153 			    th, tp->t_state, rack,
4154 			    tp->snd_una, tp->snd_max, tp->snd_nxt, changed);
4155 #endif
4156 			goto proc_sack;
4157 		}
4158 		if (SEQ_LT(th_ack, rsm->r_start)) {
4159 			/* Huh map is missing this */
4160 #ifdef INVARIANTS
4161 			printf("Rack map starts at r_start:%u for th_ack:%u huh? ts:%d rs:%d\n",
4162 			    rsm->r_start,
4163 			    th_ack, tp->t_state, rack->r_state);
4164 #endif
4165 			goto proc_sack;
4166 		}
4167 		rack_update_rtt(tp, rack, rsm, to, cts, CUM_ACKED);
4168 		/* Now do we consume the whole thing? */
4169 		if (SEQ_GEQ(th_ack, rsm->r_end)) {
4170 			/* Its all consumed. */
4171 			uint32_t left;
4172 
4173 			rack->r_ctl.rc_holes_rxt -= rsm->r_rtr_bytes;
4174 			rsm->r_rtr_bytes = 0;
4175 			TAILQ_REMOVE(&rack->r_ctl.rc_map, rsm, r_next);
4176 			if (rsm->r_in_tmap) {
4177 				TAILQ_REMOVE(&rack->r_ctl.rc_tmap, rsm, r_tnext);
4178 				rsm->r_in_tmap = 0;
4179 			}
4180 			if (rack->r_ctl.rc_next == rsm) {
4181 				/* scoot along the marker */
4182 				rack->r_ctl.rc_next = TAILQ_FIRST(&rack->r_ctl.rc_map);
4183 			}
4184 			if (rsm->r_flags & RACK_ACKED) {
4185 				/*
4186 				 * It was acked on the scoreboard -- remove
4187 				 * it from total
4188 				 */
4189 				rack->r_ctl.rc_sacked -= (rsm->r_end - rsm->r_start);
4190 			} else if (rsm->r_flags & RACK_SACK_PASSED) {
4191 				/*
4192 				 * There are acked segments ACKED on the
4193 				 * scoreboard further up. We are seeing
4194 				 * reordering.
4195 				 */
4196 				counter_u64_add(rack_reorder_seen, 1);
4197 				rsm->r_flags |= RACK_ACKED;
4198 				rack->r_ctl.rc_reorder_ts = cts;
4199 			}
4200 			left = th_ack - rsm->r_end;
4201 			if (rsm->r_rtr_cnt > 1) {
4202 				/*
4203 				 * Technically we should make r_rtr_cnt be
4204 				 * monotonicly increasing and just mod it to
4205 				 * the timestamp it is replacing.. that way
4206 				 * we would have the last 3 retransmits. Now
4207 				 * rc_loss_count will be wrong if we
4208 				 * retransmit something more than 2 times in
4209 				 * recovery :(
4210 				 */
4211 				rack->r_ctl.rc_loss_count += (rsm->r_rtr_cnt - 1);
4212 			}
4213 			/* Free back to zone */
4214 			rack_free(rack, rsm);
4215 			if (left) {
4216 				goto more;
4217 			}
4218 			goto proc_sack;
4219 		}
4220 		if (rsm->r_flags & RACK_ACKED) {
4221 			/*
4222 			 * It was acked on the scoreboard -- remove it from
4223 			 * total for the part being cum-acked.
4224 			 */
4225 			rack->r_ctl.rc_sacked -= (th_ack - rsm->r_start);
4226 		}
4227 		rack->r_ctl.rc_holes_rxt -= rsm->r_rtr_bytes;
4228 		rsm->r_rtr_bytes = 0;
4229 		rsm->r_start = th_ack;
4230 	}
4231 proc_sack:
4232 	/* Check for reneging */
4233 	rsm = TAILQ_FIRST(&rack->r_ctl.rc_map);
4234 	if (rsm && (rsm->r_flags & RACK_ACKED) && (th_ack == rsm->r_start)) {
4235 		/*
4236 		 * The peer has moved snd_una up to
4237 		 * the edge of this send, i.e. one
4238 		 * that it had previously acked. The only
4239 		 * way that can be true if the peer threw
4240 		 * away data (space issues) that it had
4241 		 * previously sacked (else it would have
4242 		 * given us snd_una up to (rsm->r_end).
4243 		 * We need to undo the acked markings here.
4244 		 *
4245 		 * Note we have to look to make sure th_ack is
4246 		 * our rsm->r_start in case we get an old ack
4247 		 * where th_ack is behind snd_una.
4248 		 */
4249 		rack_peer_reneges(rack, rsm, th->th_ack);
4250 	}
4251 	if ((to->to_flags & TOF_SACK) == 0) {
4252 		/* We are done nothing left to log */
4253 		goto out;
4254 	}
4255 	rsm = TAILQ_LAST_FAST(&rack->r_ctl.rc_map, rack_sendmap, r_next);
4256 	if (rsm) {
4257 		last_seq = rsm->r_end;
4258 	} else {
4259 		last_seq = tp->snd_max;
4260 	}
4261 	/* Sack block processing */
4262 	if (SEQ_GT(th_ack, tp->snd_una))
4263 		ack_point = th_ack;
4264 	else
4265 		ack_point = tp->snd_una;
4266 	for (i = 0; i < to->to_nsacks; i++) {
4267 		bcopy((to->to_sacks + i * TCPOLEN_SACK),
4268 		    &sack, sizeof(sack));
4269 		sack.start = ntohl(sack.start);
4270 		sack.end = ntohl(sack.end);
4271 		if (SEQ_GT(sack.end, sack.start) &&
4272 		    SEQ_GT(sack.start, ack_point) &&
4273 		    SEQ_LT(sack.start, tp->snd_max) &&
4274 		    SEQ_GT(sack.end, ack_point) &&
4275 		    SEQ_LEQ(sack.end, tp->snd_max)) {
4276 			if ((rack->r_ctl.rc_num_maps_alloced > rack_sack_block_limit) &&
4277 			    (SEQ_LT(sack.end, last_seq)) &&
4278 			    ((sack.end - sack.start) < (tp->t_maxseg / 8))) {
4279 				/*
4280 				 * Not the last piece and its smaller than
4281 				 * 1/8th of a MSS. We ignore this.
4282 				 */
4283 				counter_u64_add(rack_runt_sacks, 1);
4284 				continue;
4285 			}
4286 			sack_blocks[num_sack_blks] = sack;
4287 			num_sack_blks++;
4288 #ifdef NETFLIX_STATS
4289 		} else if (SEQ_LEQ(sack.start, th_ack) &&
4290 			   SEQ_LEQ(sack.end, th_ack)) {
4291 			/*
4292 			 * Its a D-SACK block.
4293 			 */
4294 			tcp_record_dsack(sack.start, sack.end);
4295 #endif
4296 		}
4297 
4298 	}
4299 	if (num_sack_blks == 0)
4300 		goto out;
4301 	/*
4302 	 * Sort the SACK blocks so we can update the rack scoreboard with
4303 	 * just one pass.
4304 	 */
4305 	if (rack_use_sack_filter) {
4306 		num_sack_blks = sack_filter_blks(&rack->r_ctl.rack_sf, sack_blocks, num_sack_blks, th->th_ack);
4307 	}
4308 	if (num_sack_blks < 2) {
4309 		goto do_sack_work;
4310 	}
4311 	/* Sort the sacks */
4312 	for (i = 0; i < num_sack_blks; i++) {
4313 		for (j = i + 1; j < num_sack_blks; j++) {
4314 			if (SEQ_GT(sack_blocks[i].end, sack_blocks[j].end)) {
4315 				sack = sack_blocks[i];
4316 				sack_blocks[i] = sack_blocks[j];
4317 				sack_blocks[j] = sack;
4318 			}
4319 		}
4320 	}
4321 	/*
4322 	 * Now are any of the sack block ends the same (yes some
4323 	 * implememtations send these)?
4324 	 */
4325 again:
4326 	if (num_sack_blks > 1) {
4327 		for (i = 0; i < num_sack_blks; i++) {
4328 			for (j = i + 1; j < num_sack_blks; j++) {
4329 				if (sack_blocks[i].end == sack_blocks[j].end) {
4330 					/*
4331 					 * Ok these two have the same end we
4332 					 * want the smallest end and then
4333 					 * throw away the larger and start
4334 					 * again.
4335 					 */
4336 					if (SEQ_LT(sack_blocks[j].start, sack_blocks[i].start)) {
4337 						/*
4338 						 * The second block covers
4339 						 * more area use that
4340 						 */
4341 						sack_blocks[i].start = sack_blocks[j].start;
4342 					}
4343 					/*
4344 					 * Now collapse out the dup-sack and
4345 					 * lower the count
4346 					 */
4347 					for (k = (j + 1); k < num_sack_blks; k++) {
4348 						sack_blocks[j].start = sack_blocks[k].start;
4349 						sack_blocks[j].end = sack_blocks[k].end;
4350 						j++;
4351 					}
4352 					num_sack_blks--;
4353 					goto again;
4354 				}
4355 			}
4356 		}
4357 	}
4358 do_sack_work:
4359 	rsm = rack->r_ctl.rc_sacklast;
4360 	for (i = 0; i < num_sack_blks; i++) {
4361 		acked = rack_proc_sack_blk(tp, rack, &sack_blocks[i], to, &rsm, cts);
4362 		if (acked) {
4363 			rack->r_wanted_output++;
4364 			changed += acked;
4365 			sack_changed += acked;
4366 		}
4367 	}
4368 out:
4369 	if (changed) {
4370 		/* Something changed cancel the rack timer */
4371 		rack_timer_cancel(tp, rack, rack->r_ctl.rc_rcvtime, __LINE__);
4372 	}
4373 	if ((sack_changed) && (!IN_RECOVERY(tp->t_flags))) {
4374 		/*
4375 		 * Ok we have a high probability that we need to go in to
4376 		 * recovery since we have data sack'd
4377 		 */
4378 		struct rack_sendmap *rsm;
4379 		uint32_t tsused;
4380 
4381 		tsused = tcp_ts_getticks();
4382 		rsm = tcp_rack_output(tp, rack, tsused);
4383 		if (rsm) {
4384 			/* Enter recovery */
4385 			rack->r_ctl.rc_rsm_start = rsm->r_start;
4386 			rack->r_ctl.rc_cwnd_at = tp->snd_cwnd;
4387 			rack->r_ctl.rc_ssthresh_at = tp->snd_ssthresh;
4388 			entered_recovery = 1;
4389 			rack_cong_signal(tp, NULL, CC_NDUPACK);
4390 			/*
4391 			 * When we enter recovery we need to assure we send
4392 			 * one packet.
4393 			 */
4394 			rack->r_ctl.rc_prr_sndcnt = tp->t_maxseg;
4395 			rack->r_timer_override = 1;
4396 		}
4397 	}
4398 	if (IN_RECOVERY(tp->t_flags) && (entered_recovery == 0)) {
4399 		/* Deal with changed an PRR here (in recovery only) */
4400 		uint32_t pipe, snd_una;
4401 
4402 		rack->r_ctl.rc_prr_delivered += changed;
4403 		/* Compute prr_sndcnt */
4404 		if (SEQ_GT(tp->snd_una, th_ack)) {
4405 			snd_una = tp->snd_una;
4406 		} else {
4407 			snd_una = th_ack;
4408 		}
4409 		pipe = ((tp->snd_max - snd_una) - rack->r_ctl.rc_sacked) + rack->r_ctl.rc_holes_rxt;
4410 		if (pipe > tp->snd_ssthresh) {
4411 			long sndcnt;
4412 
4413 			sndcnt = rack->r_ctl.rc_prr_delivered * tp->snd_ssthresh;
4414 			if (rack->r_ctl.rc_prr_recovery_fs > 0)
4415 				sndcnt /= (long)rack->r_ctl.rc_prr_recovery_fs;
4416 			else {
4417 				rack->r_ctl.rc_prr_sndcnt = 0;
4418 				sndcnt = 0;
4419 			}
4420 			sndcnt++;
4421 			if (sndcnt > (long)rack->r_ctl.rc_prr_out)
4422 				sndcnt -= rack->r_ctl.rc_prr_out;
4423 			else
4424 				sndcnt = 0;
4425 			rack->r_ctl.rc_prr_sndcnt = sndcnt;
4426 		} else {
4427 			uint32_t limit;
4428 
4429 			if (rack->r_ctl.rc_prr_delivered > rack->r_ctl.rc_prr_out)
4430 				limit = (rack->r_ctl.rc_prr_delivered - rack->r_ctl.rc_prr_out);
4431 			else
4432 				limit = 0;
4433 			if (changed > limit)
4434 				limit = changed;
4435 			limit += tp->t_maxseg;
4436 			if (tp->snd_ssthresh > pipe) {
4437 				rack->r_ctl.rc_prr_sndcnt = min((tp->snd_ssthresh - pipe), limit);
4438 			} else {
4439 				rack->r_ctl.rc_prr_sndcnt = min(0, limit);
4440 			}
4441 		}
4442 		if (rack->r_ctl.rc_prr_sndcnt >= tp->t_maxseg) {
4443 			rack->r_timer_override = 1;
4444 		}
4445 	}
4446 }
4447 
4448 /*
4449  * Return value of 1, we do not need to call rack_process_data().
4450  * return value of 0, rack_process_data can be called.
4451  * For ret_val if its 0 the TCP is locked, if its non-zero
4452  * its unlocked and probably unsafe to touch the TCB.
4453  */
4454 static int
4455 rack_process_ack(struct mbuf *m, struct tcphdr *th, struct socket *so,
4456     struct tcpcb *tp, struct tcpopt *to,
4457     uint32_t tiwin, int32_t tlen,
4458     int32_t * ofia, int32_t thflags, int32_t * ret_val)
4459 {
4460 	int32_t ourfinisacked = 0;
4461 	int32_t nsegs, acked_amount;
4462 	int32_t acked;
4463 	struct mbuf *mfree;
4464 	struct tcp_rack *rack;
4465 	int32_t recovery = 0;
4466 
4467 	rack = (struct tcp_rack *)tp->t_fb_ptr;
4468 	if (SEQ_GT(th->th_ack, tp->snd_max)) {
4469 		rack_do_dropafterack(m, tp, th, thflags, tlen, ret_val);
4470 		return (1);
4471 	}
4472 	if (SEQ_GEQ(th->th_ack, tp->snd_una) || to->to_nsacks) {
4473 		rack_log_ack(tp, to, th);
4474 	}
4475 	if (__predict_false(SEQ_LEQ(th->th_ack, tp->snd_una))) {
4476 		/*
4477 		 * Old ack, behind (or duplicate to) the last one rcv'd
4478 		 * Note: Should mark reordering is occuring! We should also
4479 		 * look for sack blocks arriving e.g. ack 1, 4-4 then ack 1,
4480 		 * 3-3, 4-4 would be reording. As well as ack 1, 3-3 <no
4481 		 * retran and> ack 3
4482 		 */
4483 		return (0);
4484 	}
4485 	/*
4486 	 * If we reach this point, ACK is not a duplicate, i.e., it ACKs
4487 	 * something we sent.
4488 	 */
4489 	if (tp->t_flags & TF_NEEDSYN) {
4490 		/*
4491 		 * T/TCP: Connection was half-synchronized, and our SYN has
4492 		 * been ACK'd (so connection is now fully synchronized).  Go
4493 		 * to non-starred state, increment snd_una for ACK of SYN,
4494 		 * and check if we can do window scaling.
4495 		 */
4496 		tp->t_flags &= ~TF_NEEDSYN;
4497 		tp->snd_una++;
4498 		/* Do window scaling? */
4499 		if ((tp->t_flags & (TF_RCVD_SCALE | TF_REQ_SCALE)) ==
4500 		    (TF_RCVD_SCALE | TF_REQ_SCALE)) {
4501 			tp->rcv_scale = tp->request_r_scale;
4502 			/* Send window already scaled. */
4503 		}
4504 	}
4505 	nsegs = max(1, m->m_pkthdr.lro_nsegs);
4506 	INP_WLOCK_ASSERT(tp->t_inpcb);
4507 
4508 	acked = BYTES_THIS_ACK(tp, th);
4509 	TCPSTAT_ADD(tcps_rcvackpack, nsegs);
4510 	TCPSTAT_ADD(tcps_rcvackbyte, acked);
4511 
4512 	/*
4513 	 * If we just performed our first retransmit, and the ACK arrives
4514 	 * within our recovery window, then it was a mistake to do the
4515 	 * retransmit in the first place.  Recover our original cwnd and
4516 	 * ssthresh, and proceed to transmit where we left off.
4517 	 */
4518 	if (tp->t_flags & TF_PREVVALID) {
4519 		tp->t_flags &= ~TF_PREVVALID;
4520 		if (tp->t_rxtshift == 1 &&
4521 		    (int)(ticks - tp->t_badrxtwin) < 0)
4522 			rack_cong_signal(tp, th, CC_RTO_ERR);
4523 	}
4524 	/*
4525 	 * If we have a timestamp reply, update smoothed round trip time. If
4526 	 * no timestamp is present but transmit timer is running and timed
4527 	 * sequence number was acked, update smoothed round trip time. Since
4528 	 * we now have an rtt measurement, cancel the timer backoff (cf.,
4529 	 * Phil Karn's retransmit alg.). Recompute the initial retransmit
4530 	 * timer.
4531 	 *
4532 	 * Some boxes send broken timestamp replies during the SYN+ACK
4533 	 * phase, ignore timestamps of 0 or we could calculate a huge RTT
4534 	 * and blow up the retransmit timer.
4535 	 */
4536 	/*
4537 	 * If all outstanding data is acked, stop retransmit timer and
4538 	 * remember to restart (more output or persist). If there is more
4539 	 * data to be acked, restart retransmit timer, using current
4540 	 * (possibly backed-off) value.
4541 	 */
4542 	if (th->th_ack == tp->snd_max) {
4543 		rack_timer_cancel(tp, rack, rack->r_ctl.rc_rcvtime, __LINE__);
4544 		rack->r_wanted_output++;
4545 	}
4546 	/*
4547 	 * If no data (only SYN) was ACK'd, skip rest of ACK processing.
4548 	 */
4549 	if (acked == 0) {
4550 		if (ofia)
4551 			*ofia = ourfinisacked;
4552 		return (0);
4553 	}
4554 	if (rack->r_ctl.rc_early_recovery) {
4555 		if (IN_FASTRECOVERY(tp->t_flags)) {
4556 			if (SEQ_LT(th->th_ack, tp->snd_recover)) {
4557 				tcp_rack_partialack(tp, th);
4558 			} else {
4559 				rack_post_recovery(tp, th);
4560 				recovery = 1;
4561 			}
4562 		}
4563 	}
4564 	/*
4565 	 * Let the congestion control algorithm update congestion control
4566 	 * related information. This typically means increasing the
4567 	 * congestion window.
4568 	 */
4569 	rack_ack_received(tp, rack, th, nsegs, CC_ACK, recovery);
4570 	SOCKBUF_LOCK(&so->so_snd);
4571 	acked_amount = min(acked, (int)sbavail(&so->so_snd));
4572 	tp->snd_wnd -= acked_amount;
4573 	mfree = sbcut_locked(&so->so_snd, acked_amount);
4574 	if ((sbused(&so->so_snd) == 0) &&
4575 	    (acked > acked_amount) &&
4576 	    (tp->t_state >= TCPS_FIN_WAIT_1)) {
4577 		ourfinisacked = 1;
4578 	}
4579 	/* NB: sowwakeup_locked() does an implicit unlock. */
4580 	sowwakeup_locked(so);
4581 	m_freem(mfree);
4582 	if (rack->r_ctl.rc_early_recovery == 0) {
4583 		if (IN_FASTRECOVERY(tp->t_flags)) {
4584 			if (SEQ_LT(th->th_ack, tp->snd_recover)) {
4585 				tcp_rack_partialack(tp, th);
4586 			} else {
4587 				rack_post_recovery(tp, th);
4588 			}
4589 		}
4590 	}
4591 	tp->snd_una = th->th_ack;
4592 	if (SEQ_GT(tp->snd_una, tp->snd_recover))
4593 		tp->snd_recover = tp->snd_una;
4594 
4595 	if (SEQ_LT(tp->snd_nxt, tp->snd_una)) {
4596 		tp->snd_nxt = tp->snd_una;
4597 	}
4598 	if (tp->snd_una == tp->snd_max) {
4599 		/* Nothing left outstanding */
4600 		rack_log_progress_event(rack, tp, 0, PROGRESS_CLEAR, __LINE__);
4601 		tp->t_acktime = 0;
4602 		rack_timer_cancel(tp, rack, rack->r_ctl.rc_rcvtime, __LINE__);
4603 		/* Set need output so persist might get set */
4604 		rack->r_wanted_output++;
4605 		if (rack_use_sack_filter)
4606 			sack_filter_clear(&rack->r_ctl.rack_sf, tp->snd_una);
4607 		if ((tp->t_state >= TCPS_FIN_WAIT_1) &&
4608 		    (sbavail(&so->so_snd) == 0) &&
4609 		    (tp->t_flags2 & TF2_DROP_AF_DATA)) {
4610 			/*
4611 			 * The socket was gone and the
4612 			 * peer sent data, time to
4613 			 * reset him.
4614 			 */
4615 			*ret_val = 1;
4616 			tp = tcp_close(tp);
4617 			rack_do_dropwithreset(m, tp, th, BANDLIM_UNLIMITED, tlen);
4618 			return (1);
4619 		}
4620 	}
4621 	if (ofia)
4622 		*ofia = ourfinisacked;
4623 	return (0);
4624 }
4625 
4626 
4627 /*
4628  * Return value of 1, the TCB is unlocked and most
4629  * likely gone, return value of 0, the TCP is still
4630  * locked.
4631  */
4632 static int
4633 rack_process_data(struct mbuf *m, struct tcphdr *th, struct socket *so,
4634     struct tcpcb *tp, int32_t drop_hdrlen, int32_t tlen,
4635     uint32_t tiwin, int32_t thflags, int32_t nxt_pkt)
4636 {
4637 	/*
4638 	 * Update window information. Don't look at window if no ACK: TAC's
4639 	 * send garbage on first SYN.
4640 	 */
4641 	int32_t nsegs;
4642 	int32_t tfo_syn;
4643 	struct tcp_rack *rack;
4644 
4645 	rack = (struct tcp_rack *)tp->t_fb_ptr;
4646 	INP_WLOCK_ASSERT(tp->t_inpcb);
4647 	nsegs = max(1, m->m_pkthdr.lro_nsegs);
4648 	if ((thflags & TH_ACK) &&
4649 	    (SEQ_LT(tp->snd_wl1, th->th_seq) ||
4650 	    (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) ||
4651 	    (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) {
4652 		/* keep track of pure window updates */
4653 		if (tlen == 0 &&
4654 		    tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd)
4655 			TCPSTAT_INC(tcps_rcvwinupd);
4656 		tp->snd_wnd = tiwin;
4657 		tp->snd_wl1 = th->th_seq;
4658 		tp->snd_wl2 = th->th_ack;
4659 		if (tp->snd_wnd > tp->max_sndwnd)
4660 			tp->max_sndwnd = tp->snd_wnd;
4661 		rack->r_wanted_output++;
4662 	} else if (thflags & TH_ACK) {
4663 		if ((tp->snd_wl2 == th->th_ack) && (tiwin < tp->snd_wnd)) {
4664 			tp->snd_wnd = tiwin;
4665 			tp->snd_wl1 = th->th_seq;
4666 			tp->snd_wl2 = th->th_ack;
4667 		}
4668 	}
4669 	/* Was persist timer active and now we have window space? */
4670 	if ((rack->rc_in_persist != 0) && tp->snd_wnd) {
4671 		rack_exit_persist(tp, rack);
4672 		tp->snd_nxt = tp->snd_max;
4673 		/* Make sure we output to start the timer */
4674 		rack->r_wanted_output++;
4675 	}
4676 	if (tp->t_flags2 & TF2_DROP_AF_DATA) {
4677 		m_freem(m);
4678 		return (0);
4679 	}
4680 	/*
4681 	 * Process segments with URG.
4682 	 */
4683 	if ((thflags & TH_URG) && th->th_urp &&
4684 	    TCPS_HAVERCVDFIN(tp->t_state) == 0) {
4685 		/*
4686 		 * This is a kludge, but if we receive and accept random
4687 		 * urgent pointers, we'll crash in soreceive.  It's hard to
4688 		 * imagine someone actually wanting to send this much urgent
4689 		 * data.
4690 		 */
4691 		SOCKBUF_LOCK(&so->so_rcv);
4692 		if (th->th_urp + sbavail(&so->so_rcv) > sb_max) {
4693 			th->th_urp = 0;	/* XXX */
4694 			thflags &= ~TH_URG;	/* XXX */
4695 			SOCKBUF_UNLOCK(&so->so_rcv);	/* XXX */
4696 			goto dodata;	/* XXX */
4697 		}
4698 		/*
4699 		 * If this segment advances the known urgent pointer, then
4700 		 * mark the data stream.  This should not happen in
4701 		 * CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since a
4702 		 * FIN has been received from the remote side. In these
4703 		 * states we ignore the URG.
4704 		 *
4705 		 * According to RFC961 (Assigned Protocols), the urgent
4706 		 * pointer points to the last octet of urgent data.  We
4707 		 * continue, however, to consider it to indicate the first
4708 		 * octet of data past the urgent section as the original
4709 		 * spec states (in one of two places).
4710 		 */
4711 		if (SEQ_GT(th->th_seq + th->th_urp, tp->rcv_up)) {
4712 			tp->rcv_up = th->th_seq + th->th_urp;
4713 			so->so_oobmark = sbavail(&so->so_rcv) +
4714 			    (tp->rcv_up - tp->rcv_nxt) - 1;
4715 			if (so->so_oobmark == 0)
4716 				so->so_rcv.sb_state |= SBS_RCVATMARK;
4717 			sohasoutofband(so);
4718 			tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA);
4719 		}
4720 		SOCKBUF_UNLOCK(&so->so_rcv);
4721 		/*
4722 		 * Remove out of band data so doesn't get presented to user.
4723 		 * This can happen independent of advancing the URG pointer,
4724 		 * but if two URG's are pending at once, some out-of-band
4725 		 * data may creep in... ick.
4726 		 */
4727 		if (th->th_urp <= (uint32_t) tlen &&
4728 		    !(so->so_options & SO_OOBINLINE)) {
4729 			/* hdr drop is delayed */
4730 			tcp_pulloutofband(so, th, m, drop_hdrlen);
4731 		}
4732 	} else {
4733 		/*
4734 		 * If no out of band data is expected, pull receive urgent
4735 		 * pointer along with the receive window.
4736 		 */
4737 		if (SEQ_GT(tp->rcv_nxt, tp->rcv_up))
4738 			tp->rcv_up = tp->rcv_nxt;
4739 	}
4740 dodata:				/* XXX */
4741 	INP_WLOCK_ASSERT(tp->t_inpcb);
4742 
4743 	/*
4744 	 * Process the segment text, merging it into the TCP sequencing
4745 	 * queue, and arranging for acknowledgment of receipt if necessary.
4746 	 * This process logically involves adjusting tp->rcv_wnd as data is
4747 	 * presented to the user (this happens in tcp_usrreq.c, case
4748 	 * PRU_RCVD).  If a FIN has already been received on this connection
4749 	 * then we just ignore the text.
4750 	 */
4751 	tfo_syn = ((tp->t_state == TCPS_SYN_RECEIVED) &&
4752 		   IS_FASTOPEN(tp->t_flags));
4753 	if ((tlen || (thflags & TH_FIN) || tfo_syn) &&
4754 	    TCPS_HAVERCVDFIN(tp->t_state) == 0) {
4755 		tcp_seq save_start = th->th_seq;
4756 
4757 		m_adj(m, drop_hdrlen);	/* delayed header drop */
4758 		/*
4759 		 * Insert segment which includes th into TCP reassembly
4760 		 * queue with control block tp.  Set thflags to whether
4761 		 * reassembly now includes a segment with FIN.  This handles
4762 		 * the common case inline (segment is the next to be
4763 		 * received on an established connection, and the queue is
4764 		 * empty), avoiding linkage into and removal from the queue
4765 		 * and repetition of various conversions. Set DELACK for
4766 		 * segments received in order, but ack immediately when
4767 		 * segments are out of order (so fast retransmit can work).
4768 		 */
4769 		if (th->th_seq == tp->rcv_nxt &&
4770 		    SEGQ_EMPTY(tp) &&
4771 		    (TCPS_HAVEESTABLISHED(tp->t_state) ||
4772 		    tfo_syn)) {
4773 			if (DELAY_ACK(tp, tlen) || tfo_syn) {
4774 				rack_timer_cancel(tp, rack, rack->r_ctl.rc_rcvtime, __LINE__);
4775 				tp->t_flags |= TF_DELACK;
4776 			} else {
4777 				rack->r_wanted_output++;
4778 				tp->t_flags |= TF_ACKNOW;
4779 			}
4780 			tp->rcv_nxt += tlen;
4781 			thflags = th->th_flags & TH_FIN;
4782 			TCPSTAT_ADD(tcps_rcvpack, nsegs);
4783 			TCPSTAT_ADD(tcps_rcvbyte, tlen);
4784 			SOCKBUF_LOCK(&so->so_rcv);
4785 			if (so->so_rcv.sb_state & SBS_CANTRCVMORE)
4786 				m_freem(m);
4787 			else
4788 				sbappendstream_locked(&so->so_rcv, m, 0);
4789 			/* NB: sorwakeup_locked() does an implicit unlock. */
4790 			sorwakeup_locked(so);
4791 		} else {
4792 			/*
4793 			 * XXX: Due to the header drop above "th" is
4794 			 * theoretically invalid by now.  Fortunately
4795 			 * m_adj() doesn't actually frees any mbufs when
4796 			 * trimming from the head.
4797 			 */
4798 			thflags = tcp_reass(tp, th, &save_start, &tlen, m);
4799 			tp->t_flags |= TF_ACKNOW;
4800 		}
4801 		if (tlen > 0)
4802 			tcp_update_sack_list(tp, save_start, save_start + tlen);
4803 	} else {
4804 		m_freem(m);
4805 		thflags &= ~TH_FIN;
4806 	}
4807 
4808 	/*
4809 	 * If FIN is received ACK the FIN and let the user know that the
4810 	 * connection is closing.
4811 	 */
4812 	if (thflags & TH_FIN) {
4813 		if (TCPS_HAVERCVDFIN(tp->t_state) == 0) {
4814 			socantrcvmore(so);
4815 			/*
4816 			 * If connection is half-synchronized (ie NEEDSYN
4817 			 * flag on) then delay ACK, so it may be piggybacked
4818 			 * when SYN is sent. Otherwise, since we received a
4819 			 * FIN then no more input can be expected, send ACK
4820 			 * now.
4821 			 */
4822 			if (tp->t_flags & TF_NEEDSYN) {
4823 				rack_timer_cancel(tp, rack, rack->r_ctl.rc_rcvtime, __LINE__);
4824 				tp->t_flags |= TF_DELACK;
4825 			} else {
4826 				tp->t_flags |= TF_ACKNOW;
4827 			}
4828 			tp->rcv_nxt++;
4829 		}
4830 		switch (tp->t_state) {
4831 
4832 			/*
4833 			 * In SYN_RECEIVED and ESTABLISHED STATES enter the
4834 			 * CLOSE_WAIT state.
4835 			 */
4836 		case TCPS_SYN_RECEIVED:
4837 			tp->t_starttime = ticks;
4838 			/* FALLTHROUGH */
4839 		case TCPS_ESTABLISHED:
4840 			rack_timer_cancel(tp, rack, rack->r_ctl.rc_rcvtime, __LINE__);
4841 			tcp_state_change(tp, TCPS_CLOSE_WAIT);
4842 			break;
4843 
4844 			/*
4845 			 * If still in FIN_WAIT_1 STATE FIN has not been
4846 			 * acked so enter the CLOSING state.
4847 			 */
4848 		case TCPS_FIN_WAIT_1:
4849 			rack_timer_cancel(tp, rack, rack->r_ctl.rc_rcvtime, __LINE__);
4850 			tcp_state_change(tp, TCPS_CLOSING);
4851 			break;
4852 
4853 			/*
4854 			 * In FIN_WAIT_2 state enter the TIME_WAIT state,
4855 			 * starting the time-wait timer, turning off the
4856 			 * other standard timers.
4857 			 */
4858 		case TCPS_FIN_WAIT_2:
4859 			rack_timer_cancel(tp, rack, rack->r_ctl.rc_rcvtime, __LINE__);
4860 			INP_INFO_RLOCK_ASSERT(&V_tcbinfo);
4861 			tcp_twstart(tp);
4862 			return (1);
4863 		}
4864 	}
4865 	/*
4866 	 * Return any desired output.
4867 	 */
4868 	if ((tp->t_flags & TF_ACKNOW) || (sbavail(&so->so_snd) > (tp->snd_max - tp->snd_una))) {
4869 		rack->r_wanted_output++;
4870 	}
4871 	INP_WLOCK_ASSERT(tp->t_inpcb);
4872 	return (0);
4873 }
4874 
4875 /*
4876  * Here nothing is really faster, its just that we
4877  * have broken out the fast-data path also just like
4878  * the fast-ack.
4879  */
4880 static int
4881 rack_do_fastnewdata(struct mbuf *m, struct tcphdr *th, struct socket *so,
4882     struct tcpcb *tp, struct tcpopt *to, int32_t drop_hdrlen, int32_t tlen,
4883     uint32_t tiwin, int32_t nxt_pkt)
4884 {
4885 	int32_t nsegs;
4886 	int32_t newsize = 0;	/* automatic sockbuf scaling */
4887 	struct tcp_rack *rack;
4888 #ifdef TCPDEBUG
4889 	/*
4890 	 * The size of tcp_saveipgen must be the size of the max ip header,
4891 	 * now IPv6.
4892 	 */
4893 	u_char tcp_saveipgen[IP6_HDR_LEN];
4894 	struct tcphdr tcp_savetcp;
4895 	short ostate = 0;
4896 
4897 #endif
4898 	/*
4899 	 * If last ACK falls within this segment's sequence numbers, record
4900 	 * the timestamp. NOTE that the test is modified according to the
4901 	 * latest proposal of the tcplw@cray.com list (Braden 1993/04/26).
4902 	 */
4903 	if (__predict_false(th->th_seq != tp->rcv_nxt)) {
4904 		return (0);
4905 	}
4906 	if (__predict_false(tp->snd_nxt != tp->snd_max)) {
4907 		return (0);
4908 	}
4909 	if (tiwin && tiwin != tp->snd_wnd) {
4910 		return (0);
4911 	}
4912 	if (__predict_false((tp->t_flags & (TF_NEEDSYN | TF_NEEDFIN)))) {
4913 		return (0);
4914 	}
4915 	if (__predict_false((to->to_flags & TOF_TS) &&
4916 	    (TSTMP_LT(to->to_tsval, tp->ts_recent)))) {
4917 		return (0);
4918 	}
4919 	if (__predict_false((th->th_ack != tp->snd_una))) {
4920 		return (0);
4921 	}
4922 	if (__predict_false(tlen > sbspace(&so->so_rcv))) {
4923 		return (0);
4924 	}
4925 	if ((to->to_flags & TOF_TS) != 0 &&
4926 	    SEQ_LEQ(th->th_seq, tp->last_ack_sent)) {
4927 		tp->ts_recent_age = tcp_ts_getticks();
4928 		tp->ts_recent = to->to_tsval;
4929 	}
4930 	rack = (struct tcp_rack *)tp->t_fb_ptr;
4931 	/*
4932 	 * This is a pure, in-sequence data packet with nothing on the
4933 	 * reassembly queue and we have enough buffer space to take it.
4934 	 */
4935 	nsegs = max(1, m->m_pkthdr.lro_nsegs);
4936 
4937 
4938 	/* Clean receiver SACK report if present */
4939 	if (tp->rcv_numsacks)
4940 		tcp_clean_sackreport(tp);
4941 	TCPSTAT_INC(tcps_preddat);
4942 	tp->rcv_nxt += tlen;
4943 	/*
4944 	 * Pull snd_wl1 up to prevent seq wrap relative to th_seq.
4945 	 */
4946 	tp->snd_wl1 = th->th_seq;
4947 	/*
4948 	 * Pull rcv_up up to prevent seq wrap relative to rcv_nxt.
4949 	 */
4950 	tp->rcv_up = tp->rcv_nxt;
4951 	TCPSTAT_ADD(tcps_rcvpack, nsegs);
4952 	TCPSTAT_ADD(tcps_rcvbyte, tlen);
4953 #ifdef TCPDEBUG
4954 	if (so->so_options & SO_DEBUG)
4955 		tcp_trace(TA_INPUT, ostate, tp,
4956 		    (void *)tcp_saveipgen, &tcp_savetcp, 0);
4957 #endif
4958 	newsize = tcp_autorcvbuf(m, th, so, tp, tlen);
4959 
4960 	/* Add data to socket buffer. */
4961 	SOCKBUF_LOCK(&so->so_rcv);
4962 	if (so->so_rcv.sb_state & SBS_CANTRCVMORE) {
4963 		m_freem(m);
4964 	} else {
4965 		/*
4966 		 * Set new socket buffer size. Give up when limit is
4967 		 * reached.
4968 		 */
4969 		if (newsize)
4970 			if (!sbreserve_locked(&so->so_rcv,
4971 			    newsize, so, NULL))
4972 				so->so_rcv.sb_flags &= ~SB_AUTOSIZE;
4973 		m_adj(m, drop_hdrlen);	/* delayed header drop */
4974 		sbappendstream_locked(&so->so_rcv, m, 0);
4975 		rack_calc_rwin(so, tp);
4976 	}
4977 	/* NB: sorwakeup_locked() does an implicit unlock. */
4978 	sorwakeup_locked(so);
4979 	if (DELAY_ACK(tp, tlen)) {
4980 		rack_timer_cancel(tp, rack, rack->r_ctl.rc_rcvtime, __LINE__);
4981 		tp->t_flags |= TF_DELACK;
4982 	} else {
4983 		tp->t_flags |= TF_ACKNOW;
4984 		rack->r_wanted_output++;
4985 	}
4986 	if ((tp->snd_una == tp->snd_max) && rack_use_sack_filter)
4987 		sack_filter_clear(&rack->r_ctl.rack_sf, tp->snd_una);
4988 	return (1);
4989 }
4990 
4991 /*
4992  * This subfunction is used to try to highly optimize the
4993  * fast path. We again allow window updates that are
4994  * in sequence to remain in the fast-path. We also add
4995  * in the __predict's to attempt to help the compiler.
4996  * Note that if we return a 0, then we can *not* process
4997  * it and the caller should push the packet into the
4998  * slow-path.
4999  */
5000 static int
5001 rack_fastack(struct mbuf *m, struct tcphdr *th, struct socket *so,
5002     struct tcpcb *tp, struct tcpopt *to, int32_t drop_hdrlen, int32_t tlen,
5003     uint32_t tiwin, int32_t nxt_pkt, uint32_t cts)
5004 {
5005 	int32_t acked;
5006 	int32_t nsegs;
5007 
5008 #ifdef TCPDEBUG
5009 	/*
5010 	 * The size of tcp_saveipgen must be the size of the max ip header,
5011 	 * now IPv6.
5012 	 */
5013 	u_char tcp_saveipgen[IP6_HDR_LEN];
5014 	struct tcphdr tcp_savetcp;
5015 	short ostate = 0;
5016 
5017 #endif
5018 	struct tcp_rack *rack;
5019 
5020 	if (__predict_false(SEQ_LEQ(th->th_ack, tp->snd_una))) {
5021 		/* Old ack, behind (or duplicate to) the last one rcv'd */
5022 		return (0);
5023 	}
5024 	if (__predict_false(SEQ_GT(th->th_ack, tp->snd_max))) {
5025 		/* Above what we have sent? */
5026 		return (0);
5027 	}
5028 	if (__predict_false(tp->snd_nxt != tp->snd_max)) {
5029 		/* We are retransmitting */
5030 		return (0);
5031 	}
5032 	if (__predict_false(tiwin == 0)) {
5033 		/* zero window */
5034 		return (0);
5035 	}
5036 	if (__predict_false(tp->t_flags & (TF_NEEDSYN | TF_NEEDFIN))) {
5037 		/* We need a SYN or a FIN, unlikely.. */
5038 		return (0);
5039 	}
5040 	if ((to->to_flags & TOF_TS) && __predict_false(TSTMP_LT(to->to_tsval, tp->ts_recent))) {
5041 		/* Timestamp is behind .. old ack with seq wrap? */
5042 		return (0);
5043 	}
5044 	if (__predict_false(IN_RECOVERY(tp->t_flags))) {
5045 		/* Still recovering */
5046 		return (0);
5047 	}
5048 	rack = (struct tcp_rack *)tp->t_fb_ptr;
5049 	if (rack->r_ctl.rc_sacked) {
5050 		/* We have sack holes on our scoreboard */
5051 		return (0);
5052 	}
5053 	/* Ok if we reach here, we can process a fast-ack */
5054 	nsegs = max(1, m->m_pkthdr.lro_nsegs);
5055 	rack_log_ack(tp, to, th);
5056 	/* Did the window get updated? */
5057 	if (tiwin != tp->snd_wnd) {
5058 		tp->snd_wnd = tiwin;
5059 		tp->snd_wl1 = th->th_seq;
5060 		if (tp->snd_wnd > tp->max_sndwnd)
5061 			tp->max_sndwnd = tp->snd_wnd;
5062 	}
5063 	if ((rack->rc_in_persist != 0) && (tp->snd_wnd >= tp->t_maxseg)) {
5064 		rack_exit_persist(tp, rack);
5065 	}
5066 	/*
5067 	 * If last ACK falls within this segment's sequence numbers, record
5068 	 * the timestamp. NOTE that the test is modified according to the
5069 	 * latest proposal of the tcplw@cray.com list (Braden 1993/04/26).
5070 	 */
5071 	if ((to->to_flags & TOF_TS) != 0 &&
5072 	    SEQ_LEQ(th->th_seq, tp->last_ack_sent)) {
5073 		tp->ts_recent_age = tcp_ts_getticks();
5074 		tp->ts_recent = to->to_tsval;
5075 	}
5076 	/*
5077 	 * This is a pure ack for outstanding data.
5078 	 */
5079 	TCPSTAT_INC(tcps_predack);
5080 
5081 	/*
5082 	 * "bad retransmit" recovery.
5083 	 */
5084 	if (tp->t_flags & TF_PREVVALID) {
5085 		tp->t_flags &= ~TF_PREVVALID;
5086 		if (tp->t_rxtshift == 1 &&
5087 		    (int)(ticks - tp->t_badrxtwin) < 0)
5088 			rack_cong_signal(tp, th, CC_RTO_ERR);
5089 	}
5090 	/*
5091 	 * Recalculate the transmit timer / rtt.
5092 	 *
5093 	 * Some boxes send broken timestamp replies during the SYN+ACK
5094 	 * phase, ignore timestamps of 0 or we could calculate a huge RTT
5095 	 * and blow up the retransmit timer.
5096 	 */
5097 	acked = BYTES_THIS_ACK(tp, th);
5098 
5099 #ifdef TCP_HHOOK
5100 	/* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */
5101 	hhook_run_tcp_est_in(tp, th, to);
5102 #endif
5103 
5104 	TCPSTAT_ADD(tcps_rcvackpack, nsegs);
5105 	TCPSTAT_ADD(tcps_rcvackbyte, acked);
5106 	sbdrop(&so->so_snd, acked);
5107 	/*
5108 	 * Let the congestion control algorithm update congestion control
5109 	 * related information. This typically means increasing the
5110 	 * congestion window.
5111 	 */
5112 	rack_ack_received(tp, rack, th, nsegs, CC_ACK, 0);
5113 
5114 	tp->snd_una = th->th_ack;
5115 	/*
5116 	 * Pull snd_wl2 up to prevent seq wrap relative to th_ack.
5117 	 */
5118 	tp->snd_wl2 = th->th_ack;
5119 	tp->t_dupacks = 0;
5120 	m_freem(m);
5121 	/* ND6_HINT(tp);	 *//* Some progress has been made. */
5122 
5123 	/*
5124 	 * If all outstanding data are acked, stop retransmit timer,
5125 	 * otherwise restart timer using current (possibly backed-off)
5126 	 * value. If process is waiting for space, wakeup/selwakeup/signal.
5127 	 * If data are ready to send, let tcp_output decide between more
5128 	 * output or persist.
5129 	 */
5130 #ifdef TCPDEBUG
5131 	if (so->so_options & SO_DEBUG)
5132 		tcp_trace(TA_INPUT, ostate, tp,
5133 		    (void *)tcp_saveipgen,
5134 		    &tcp_savetcp, 0);
5135 #endif
5136 	if (tp->snd_una == tp->snd_max) {
5137 		rack_log_progress_event(rack, tp, 0, PROGRESS_CLEAR, __LINE__);
5138 		tp->t_acktime = 0;
5139 		rack_timer_cancel(tp, rack, rack->r_ctl.rc_rcvtime, __LINE__);
5140 	}
5141 	/* Wake up the socket if we have room to write more */
5142 	sowwakeup(so);
5143 	if (sbavail(&so->so_snd)) {
5144 		rack->r_wanted_output++;
5145 	}
5146 	return (1);
5147 }
5148 
5149 /*
5150  * Return value of 1, the TCB is unlocked and most
5151  * likely gone, return value of 0, the TCP is still
5152  * locked.
5153  */
5154 static int
5155 rack_do_syn_sent(struct mbuf *m, struct tcphdr *th, struct socket *so,
5156     struct tcpcb *tp, struct tcpopt *to, int32_t drop_hdrlen, int32_t tlen,
5157     uint32_t tiwin, int32_t thflags, int32_t nxt_pkt)
5158 {
5159 	int32_t ret_val = 0;
5160 	int32_t todrop;
5161 	int32_t ourfinisacked = 0;
5162 
5163 	rack_calc_rwin(so, tp);
5164 	/*
5165 	 * If the state is SYN_SENT: if seg contains an ACK, but not for our
5166 	 * SYN, drop the input. if seg contains a RST, then drop the
5167 	 * connection. if seg does not contain SYN, then drop it. Otherwise
5168 	 * this is an acceptable SYN segment initialize tp->rcv_nxt and
5169 	 * tp->irs if seg contains ack then advance tp->snd_una if seg
5170 	 * contains an ECE and ECN support is enabled, the stream is ECN
5171 	 * capable. if SYN has been acked change to ESTABLISHED else
5172 	 * SYN_RCVD state arrange for segment to be acked (eventually)
5173 	 * continue processing rest of data/controls, beginning with URG
5174 	 */
5175 	if ((thflags & TH_ACK) &&
5176 	    (SEQ_LEQ(th->th_ack, tp->iss) ||
5177 	    SEQ_GT(th->th_ack, tp->snd_max))) {
5178 		rack_do_dropwithreset(m, tp, th, BANDLIM_RST_OPENPORT, tlen);
5179 		return (1);
5180 	}
5181 	if ((thflags & (TH_ACK | TH_RST)) == (TH_ACK | TH_RST)) {
5182 		TCP_PROBE5(connect__refused, NULL, tp,
5183 		    mtod(m, const char *), tp, th);
5184 		tp = tcp_drop(tp, ECONNREFUSED);
5185 		rack_do_drop(m, tp);
5186 		return (1);
5187 	}
5188 	if (thflags & TH_RST) {
5189 		rack_do_drop(m, tp);
5190 		return (1);
5191 	}
5192 	if (!(thflags & TH_SYN)) {
5193 		rack_do_drop(m, tp);
5194 		return (1);
5195 	}
5196 	tp->irs = th->th_seq;
5197 	tcp_rcvseqinit(tp);
5198 	if (thflags & TH_ACK) {
5199 		int tfo_partial = 0;
5200 
5201 		TCPSTAT_INC(tcps_connects);
5202 		soisconnected(so);
5203 #ifdef MAC
5204 		mac_socketpeer_set_from_mbuf(m, so);
5205 #endif
5206 		/* Do window scaling on this connection? */
5207 		if ((tp->t_flags & (TF_RCVD_SCALE | TF_REQ_SCALE)) ==
5208 		    (TF_RCVD_SCALE | TF_REQ_SCALE)) {
5209 			tp->rcv_scale = tp->request_r_scale;
5210 		}
5211 		tp->rcv_adv += min(tp->rcv_wnd,
5212 		    TCP_MAXWIN << tp->rcv_scale);
5213 		/*
5214 		 * If not all the data that was sent in the TFO SYN
5215 		 * has been acked, resend the remainder right away.
5216 		 */
5217 		if (IS_FASTOPEN(tp->t_flags) &&
5218 		    (tp->snd_una != tp->snd_max)) {
5219 			tp->snd_nxt = th->th_ack;
5220 			tfo_partial = 1;
5221 		}
5222 		/*
5223 		 * If there's data, delay ACK; if there's also a FIN ACKNOW
5224 		 * will be turned on later.
5225 		 */
5226 		if (DELAY_ACK(tp, tlen) && tlen != 0 && (tfo_partial == 0)) {
5227 			rack_timer_cancel(tp, (struct tcp_rack *)tp->t_fb_ptr,
5228 					  ((struct tcp_rack *)tp->t_fb_ptr)->r_ctl.rc_rcvtime, __LINE__);
5229 			tp->t_flags |= TF_DELACK;
5230 		} else {
5231 			((struct tcp_rack *)tp->t_fb_ptr)->r_wanted_output++;
5232 			tp->t_flags |= TF_ACKNOW;
5233 		}
5234 
5235 		if (((thflags & (TH_CWR | TH_ECE)) == TH_ECE) &&
5236 		    V_tcp_do_ecn) {
5237 			tp->t_flags |= TF_ECN_PERMIT;
5238 			TCPSTAT_INC(tcps_ecn_shs);
5239 		}
5240 		if (SEQ_GT(th->th_ack, tp->snd_una)) {
5241 			/*
5242 			 * We advance snd_una for the
5243 			 * fast open case. If th_ack is
5244 			 * acknowledging data beyond
5245 			 * snd_una we can't just call
5246 			 * ack-processing since the
5247 			 * data stream in our send-map
5248 			 * will start at snd_una + 1 (one
5249 			 * beyond the SYN). If its just
5250 			 * equal we don't need to do that
5251 			 * and there is no send_map.
5252 			 */
5253 			tp->snd_una++;
5254 		}
5255 		/*
5256 		 * Received <SYN,ACK> in SYN_SENT[*] state. Transitions:
5257 		 * SYN_SENT  --> ESTABLISHED SYN_SENT* --> FIN_WAIT_1
5258 		 */
5259 		tp->t_starttime = ticks;
5260 		if (tp->t_flags & TF_NEEDFIN) {
5261 			tcp_state_change(tp, TCPS_FIN_WAIT_1);
5262 			tp->t_flags &= ~TF_NEEDFIN;
5263 			thflags &= ~TH_SYN;
5264 		} else {
5265 			tcp_state_change(tp, TCPS_ESTABLISHED);
5266 			TCP_PROBE5(connect__established, NULL, tp,
5267 			    mtod(m, const char *), tp, th);
5268 			cc_conn_init(tp);
5269 		}
5270 	} else {
5271 		/*
5272 		 * Received initial SYN in SYN-SENT[*] state => simultaneous
5273 		 * open.  If segment contains CC option and there is a
5274 		 * cached CC, apply TAO test. If it succeeds, connection is *
5275 		 * half-synchronized. Otherwise, do 3-way handshake:
5276 		 * SYN-SENT -> SYN-RECEIVED SYN-SENT* -> SYN-RECEIVED* If
5277 		 * there was no CC option, clear cached CC value.
5278 		 */
5279 		tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN);
5280 		tcp_state_change(tp, TCPS_SYN_RECEIVED);
5281 	}
5282 	INP_INFO_RLOCK_ASSERT(&V_tcbinfo);
5283 	INP_WLOCK_ASSERT(tp->t_inpcb);
5284 	/*
5285 	 * Advance th->th_seq to correspond to first data byte. If data,
5286 	 * trim to stay within window, dropping FIN if necessary.
5287 	 */
5288 	th->th_seq++;
5289 	if (tlen > tp->rcv_wnd) {
5290 		todrop = tlen - tp->rcv_wnd;
5291 		m_adj(m, -todrop);
5292 		tlen = tp->rcv_wnd;
5293 		thflags &= ~TH_FIN;
5294 		TCPSTAT_INC(tcps_rcvpackafterwin);
5295 		TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop);
5296 	}
5297 	tp->snd_wl1 = th->th_seq - 1;
5298 	tp->rcv_up = th->th_seq;
5299 	/*
5300 	 * Client side of transaction: already sent SYN and data. If the
5301 	 * remote host used T/TCP to validate the SYN, our data will be
5302 	 * ACK'd; if so, enter normal data segment processing in the middle
5303 	 * of step 5, ack processing. Otherwise, goto step 6.
5304 	 */
5305 	if (thflags & TH_ACK) {
5306 		if (rack_process_ack(m, th, so, tp, to, tiwin, tlen, &ourfinisacked, thflags, &ret_val))
5307 			return (ret_val);
5308 		/* We may have changed to FIN_WAIT_1 above */
5309 		if (tp->t_state == TCPS_FIN_WAIT_1) {
5310 			/*
5311 			 * In FIN_WAIT_1 STATE in addition to the processing
5312 			 * for the ESTABLISHED state if our FIN is now
5313 			 * acknowledged then enter FIN_WAIT_2.
5314 			 */
5315 			if (ourfinisacked) {
5316 				/*
5317 				 * If we can't receive any more data, then
5318 				 * closing user can proceed. Starting the
5319 				 * timer is contrary to the specification,
5320 				 * but if we don't get a FIN we'll hang
5321 				 * forever.
5322 				 *
5323 				 * XXXjl: we should release the tp also, and
5324 				 * use a compressed state.
5325 				 */
5326 				if (so->so_rcv.sb_state & SBS_CANTRCVMORE) {
5327 					soisdisconnected(so);
5328 					tcp_timer_activate(tp, TT_2MSL,
5329 					    (tcp_fast_finwait2_recycle ?
5330 					    tcp_finwait2_timeout :
5331 					    TP_MAXIDLE(tp)));
5332 				}
5333 				tcp_state_change(tp, TCPS_FIN_WAIT_2);
5334 			}
5335 		}
5336 	}
5337 	return (rack_process_data(m, th, so, tp, drop_hdrlen, tlen,
5338 	   tiwin, thflags, nxt_pkt));
5339 }
5340 
5341 /*
5342  * Return value of 1, the TCB is unlocked and most
5343  * likely gone, return value of 0, the TCP is still
5344  * locked.
5345  */
5346 static int
5347 rack_do_syn_recv(struct mbuf *m, struct tcphdr *th, struct socket *so,
5348     struct tcpcb *tp, struct tcpopt *to, int32_t drop_hdrlen, int32_t tlen,
5349     uint32_t tiwin, int32_t thflags, int32_t nxt_pkt)
5350 {
5351 	int32_t ret_val = 0;
5352 	int32_t ourfinisacked = 0;
5353 
5354 	rack_calc_rwin(so, tp);
5355 
5356 	if ((thflags & TH_ACK) &&
5357 	    (SEQ_LEQ(th->th_ack, tp->snd_una) ||
5358 	    SEQ_GT(th->th_ack, tp->snd_max))) {
5359 		rack_do_dropwithreset(m, tp, th, BANDLIM_RST_OPENPORT, tlen);
5360 		return (1);
5361 	}
5362 	if (IS_FASTOPEN(tp->t_flags)) {
5363 		/*
5364 		 * When a TFO connection is in SYN_RECEIVED, the
5365 		 * only valid packets are the initial SYN, a
5366 		 * retransmit/copy of the initial SYN (possibly with
5367 		 * a subset of the original data), a valid ACK, a
5368 		 * FIN, or a RST.
5369 		 */
5370 		if ((thflags & (TH_SYN | TH_ACK)) == (TH_SYN | TH_ACK)) {
5371 			rack_do_dropwithreset(m, tp, th, BANDLIM_RST_OPENPORT, tlen);
5372 			return (1);
5373 		} else if (thflags & TH_SYN) {
5374 			/* non-initial SYN is ignored */
5375 			struct tcp_rack *rack;
5376 
5377 			rack = (struct tcp_rack *)tp->t_fb_ptr;
5378 			if ((rack->r_ctl.rc_hpts_flags & PACE_TMR_RXT) ||
5379 			    (rack->r_ctl.rc_hpts_flags & PACE_TMR_TLP) ||
5380 			    (rack->r_ctl.rc_hpts_flags & PACE_TMR_RACK)) {
5381 				rack_do_drop(m, NULL);
5382 				return (0);
5383 			}
5384 		} else if (!(thflags & (TH_ACK | TH_FIN | TH_RST))) {
5385 			rack_do_drop(m, NULL);
5386 			return (0);
5387 		}
5388 	}
5389 	if (thflags & TH_RST)
5390 		return (rack_process_rst(m, th, so, tp));
5391 	/*
5392 	 * RFC 1323 PAWS: If we have a timestamp reply on this segment and
5393 	 * it's less than ts_recent, drop it.
5394 	 */
5395 	if ((to->to_flags & TOF_TS) != 0 && tp->ts_recent &&
5396 	    TSTMP_LT(to->to_tsval, tp->ts_recent)) {
5397 		if (rack_ts_check(m, th, tp, tlen, thflags, &ret_val))
5398 			return (ret_val);
5399 	}
5400 	/*
5401 	 * In the SYN-RECEIVED state, validate that the packet belongs to
5402 	 * this connection before trimming the data to fit the receive
5403 	 * window.  Check the sequence number versus IRS since we know the
5404 	 * sequence numbers haven't wrapped.  This is a partial fix for the
5405 	 * "LAND" DoS attack.
5406 	 */
5407 	if (SEQ_LT(th->th_seq, tp->irs)) {
5408 		rack_do_dropwithreset(m, tp, th, BANDLIM_RST_OPENPORT, tlen);
5409 		return (1);
5410 	}
5411 	if (rack_drop_checks(to, m, th, tp, &tlen, &thflags, &drop_hdrlen, &ret_val)) {
5412 		return (ret_val);
5413 	}
5414 	/*
5415 	 * If last ACK falls within this segment's sequence numbers, record
5416 	 * its timestamp. NOTE: 1) That the test incorporates suggestions
5417 	 * from the latest proposal of the tcplw@cray.com list (Braden
5418 	 * 1993/04/26). 2) That updating only on newer timestamps interferes
5419 	 * with our earlier PAWS tests, so this check should be solely
5420 	 * predicated on the sequence space of this segment. 3) That we
5421 	 * modify the segment boundary check to be Last.ACK.Sent <= SEG.SEQ
5422 	 * + SEG.Len  instead of RFC1323's Last.ACK.Sent < SEG.SEQ +
5423 	 * SEG.Len, This modified check allows us to overcome RFC1323's
5424 	 * limitations as described in Stevens TCP/IP Illustrated Vol. 2
5425 	 * p.869. In such cases, we can still calculate the RTT correctly
5426 	 * when RCV.NXT == Last.ACK.Sent.
5427 	 */
5428 	if ((to->to_flags & TOF_TS) != 0 &&
5429 	    SEQ_LEQ(th->th_seq, tp->last_ack_sent) &&
5430 	    SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen +
5431 	    ((thflags & (TH_SYN | TH_FIN)) != 0))) {
5432 		tp->ts_recent_age = tcp_ts_getticks();
5433 		tp->ts_recent = to->to_tsval;
5434 	}
5435 	tp->snd_wnd = tiwin;
5436 	/*
5437 	 * If the ACK bit is off:  if in SYN-RECEIVED state or SENDSYN flag
5438 	 * is on (half-synchronized state), then queue data for later
5439 	 * processing; else drop segment and return.
5440 	 */
5441 	if ((thflags & TH_ACK) == 0) {
5442 		if (IS_FASTOPEN(tp->t_flags)) {
5443 			cc_conn_init(tp);
5444 		}
5445 		return (rack_process_data(m, th, so, tp, drop_hdrlen, tlen,
5446 		    tiwin, thflags, nxt_pkt));
5447 	}
5448 	TCPSTAT_INC(tcps_connects);
5449 	soisconnected(so);
5450 	/* Do window scaling? */
5451 	if ((tp->t_flags & (TF_RCVD_SCALE | TF_REQ_SCALE)) ==
5452 	    (TF_RCVD_SCALE | TF_REQ_SCALE)) {
5453 		tp->rcv_scale = tp->request_r_scale;
5454 	}
5455 	/*
5456 	 * Make transitions: SYN-RECEIVED  -> ESTABLISHED SYN-RECEIVED* ->
5457 	 * FIN-WAIT-1
5458 	 */
5459 	tp->t_starttime = ticks;
5460 	if (IS_FASTOPEN(tp->t_flags) && tp->t_tfo_pending) {
5461 		tcp_fastopen_decrement_counter(tp->t_tfo_pending);
5462 		tp->t_tfo_pending = NULL;
5463 
5464 		/*
5465 		 * Account for the ACK of our SYN prior to
5466 		 * regular ACK processing below.
5467 		 */
5468 		tp->snd_una++;
5469 	}
5470 	if (tp->t_flags & TF_NEEDFIN) {
5471 		tcp_state_change(tp, TCPS_FIN_WAIT_1);
5472 		tp->t_flags &= ~TF_NEEDFIN;
5473 	} else {
5474 		tcp_state_change(tp, TCPS_ESTABLISHED);
5475 		TCP_PROBE5(accept__established, NULL, tp,
5476 		    mtod(m, const char *), tp, th);
5477 		/*
5478 		 * TFO connections call cc_conn_init() during SYN
5479 		 * processing.  Calling it again here for such connections
5480 		 * is not harmless as it would undo the snd_cwnd reduction
5481 		 * that occurs when a TFO SYN|ACK is retransmitted.
5482 		 */
5483 		if (!IS_FASTOPEN(tp->t_flags))
5484 			cc_conn_init(tp);
5485 	}
5486 	/*
5487 	 * If segment contains data or ACK, will call tcp_reass() later; if
5488 	 * not, do so now to pass queued data to user.
5489 	 */
5490 	if (tlen == 0 && (thflags & TH_FIN) == 0)
5491 		(void) tcp_reass(tp, (struct tcphdr *)0, NULL, 0,
5492 		    (struct mbuf *)0);
5493 	tp->snd_wl1 = th->th_seq - 1;
5494 	if (rack_process_ack(m, th, so, tp, to, tiwin, tlen, &ourfinisacked, thflags, &ret_val)) {
5495 		return (ret_val);
5496 	}
5497 	if (tp->t_state == TCPS_FIN_WAIT_1) {
5498 		/* We could have went to FIN_WAIT_1 (or EST) above */
5499 		/*
5500 		 * In FIN_WAIT_1 STATE in addition to the processing for the
5501 		 * ESTABLISHED state if our FIN is now acknowledged then
5502 		 * enter FIN_WAIT_2.
5503 		 */
5504 		if (ourfinisacked) {
5505 			/*
5506 			 * If we can't receive any more data, then closing
5507 			 * user can proceed. Starting the timer is contrary
5508 			 * to the specification, but if we don't get a FIN
5509 			 * we'll hang forever.
5510 			 *
5511 			 * XXXjl: we should release the tp also, and use a
5512 			 * compressed state.
5513 			 */
5514 			if (so->so_rcv.sb_state & SBS_CANTRCVMORE) {
5515 				soisdisconnected(so);
5516 				tcp_timer_activate(tp, TT_2MSL,
5517 				    (tcp_fast_finwait2_recycle ?
5518 				    tcp_finwait2_timeout :
5519 				    TP_MAXIDLE(tp)));
5520 			}
5521 			tcp_state_change(tp, TCPS_FIN_WAIT_2);
5522 		}
5523 	}
5524 	return (rack_process_data(m, th, so, tp, drop_hdrlen, tlen,
5525 	    tiwin, thflags, nxt_pkt));
5526 }
5527 
5528 /*
5529  * Return value of 1, the TCB is unlocked and most
5530  * likely gone, return value of 0, the TCP is still
5531  * locked.
5532  */
5533 static int
5534 rack_do_established(struct mbuf *m, struct tcphdr *th, struct socket *so,
5535     struct tcpcb *tp, struct tcpopt *to, int32_t drop_hdrlen, int32_t tlen,
5536     uint32_t tiwin, int32_t thflags, int32_t nxt_pkt)
5537 {
5538 	int32_t ret_val = 0;
5539 
5540 	/*
5541 	 * Header prediction: check for the two common cases of a
5542 	 * uni-directional data xfer.  If the packet has no control flags,
5543 	 * is in-sequence, the window didn't change and we're not
5544 	 * retransmitting, it's a candidate.  If the length is zero and the
5545 	 * ack moved forward, we're the sender side of the xfer.  Just free
5546 	 * the data acked & wake any higher level process that was blocked
5547 	 * waiting for space.  If the length is non-zero and the ack didn't
5548 	 * move, we're the receiver side.  If we're getting packets in-order
5549 	 * (the reassembly queue is empty), add the data toc The socket
5550 	 * buffer and note that we need a delayed ack. Make sure that the
5551 	 * hidden state-flags are also off. Since we check for
5552 	 * TCPS_ESTABLISHED first, it can only be TH_NEEDSYN.
5553 	 */
5554 	if (__predict_true(((to->to_flags & TOF_SACK) == 0)) &&
5555 	    __predict_true((thflags & (TH_SYN | TH_FIN | TH_RST | TH_URG | TH_ACK)) == TH_ACK) &&
5556 	    __predict_true(SEGQ_EMPTY(tp)) &&
5557 	    __predict_true(th->th_seq == tp->rcv_nxt)) {
5558 		struct tcp_rack *rack;
5559 
5560 		rack = (struct tcp_rack *)tp->t_fb_ptr;
5561 		if (tlen == 0) {
5562 			if (rack_fastack(m, th, so, tp, to, drop_hdrlen, tlen,
5563 			    tiwin, nxt_pkt, rack->r_ctl.rc_rcvtime)) {
5564 				return (0);
5565 			}
5566 		} else {
5567 			if (rack_do_fastnewdata(m, th, so, tp, to, drop_hdrlen, tlen,
5568 			    tiwin, nxt_pkt)) {
5569 				return (0);
5570 			}
5571 		}
5572 	}
5573 	rack_calc_rwin(so, tp);
5574 
5575 	if (thflags & TH_RST)
5576 		return (rack_process_rst(m, th, so, tp));
5577 
5578 	/*
5579 	 * RFC5961 Section 4.2 Send challenge ACK for any SYN in
5580 	 * synchronized state.
5581 	 */
5582 	if (thflags & TH_SYN) {
5583 		rack_challenge_ack(m, th, tp, &ret_val);
5584 		return (ret_val);
5585 	}
5586 	/*
5587 	 * RFC 1323 PAWS: If we have a timestamp reply on this segment and
5588 	 * it's less than ts_recent, drop it.
5589 	 */
5590 	if ((to->to_flags & TOF_TS) != 0 && tp->ts_recent &&
5591 	    TSTMP_LT(to->to_tsval, tp->ts_recent)) {
5592 		if (rack_ts_check(m, th, tp, tlen, thflags, &ret_val))
5593 			return (ret_val);
5594 	}
5595 	if (rack_drop_checks(to, m, th, tp, &tlen, &thflags, &drop_hdrlen, &ret_val)) {
5596 		return (ret_val);
5597 	}
5598 	/*
5599 	 * If last ACK falls within this segment's sequence numbers, record
5600 	 * its timestamp. NOTE: 1) That the test incorporates suggestions
5601 	 * from the latest proposal of the tcplw@cray.com list (Braden
5602 	 * 1993/04/26). 2) That updating only on newer timestamps interferes
5603 	 * with our earlier PAWS tests, so this check should be solely
5604 	 * predicated on the sequence space of this segment. 3) That we
5605 	 * modify the segment boundary check to be Last.ACK.Sent <= SEG.SEQ
5606 	 * + SEG.Len  instead of RFC1323's Last.ACK.Sent < SEG.SEQ +
5607 	 * SEG.Len, This modified check allows us to overcome RFC1323's
5608 	 * limitations as described in Stevens TCP/IP Illustrated Vol. 2
5609 	 * p.869. In such cases, we can still calculate the RTT correctly
5610 	 * when RCV.NXT == Last.ACK.Sent.
5611 	 */
5612 	if ((to->to_flags & TOF_TS) != 0 &&
5613 	    SEQ_LEQ(th->th_seq, tp->last_ack_sent) &&
5614 	    SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen +
5615 	    ((thflags & (TH_SYN | TH_FIN)) != 0))) {
5616 		tp->ts_recent_age = tcp_ts_getticks();
5617 		tp->ts_recent = to->to_tsval;
5618 	}
5619 	/*
5620 	 * If the ACK bit is off:  if in SYN-RECEIVED state or SENDSYN flag
5621 	 * is on (half-synchronized state), then queue data for later
5622 	 * processing; else drop segment and return.
5623 	 */
5624 	if ((thflags & TH_ACK) == 0) {
5625 		if (tp->t_flags & TF_NEEDSYN) {
5626 
5627 			return (rack_process_data(m, th, so, tp, drop_hdrlen, tlen,
5628 			    tiwin, thflags, nxt_pkt));
5629 
5630 		} else if (tp->t_flags & TF_ACKNOW) {
5631 			rack_do_dropafterack(m, tp, th, thflags, tlen, &ret_val);
5632 			return (ret_val);
5633 		} else {
5634 			rack_do_drop(m, NULL);
5635 			return (0);
5636 		}
5637 	}
5638 	/*
5639 	 * Ack processing.
5640 	 */
5641 	if (rack_process_ack(m, th, so, tp, to, tiwin, tlen, NULL, thflags, &ret_val)) {
5642 		return (ret_val);
5643 	}
5644 	if (sbavail(&so->so_snd)) {
5645 		if (rack_progress_timeout_check(tp)) {
5646 			tcp_set_inp_to_drop(tp->t_inpcb, ETIMEDOUT);
5647 			rack_do_dropwithreset(m, tp, th, BANDLIM_RST_OPENPORT, tlen);
5648 			return (1);
5649 		}
5650 	}
5651 	/* State changes only happen in rack_process_data() */
5652 	return (rack_process_data(m, th, so, tp, drop_hdrlen, tlen,
5653 	    tiwin, thflags, nxt_pkt));
5654 }
5655 
5656 /*
5657  * Return value of 1, the TCB is unlocked and most
5658  * likely gone, return value of 0, the TCP is still
5659  * locked.
5660  */
5661 static int
5662 rack_do_close_wait(struct mbuf *m, struct tcphdr *th, struct socket *so,
5663     struct tcpcb *tp, struct tcpopt *to, int32_t drop_hdrlen, int32_t tlen,
5664     uint32_t tiwin, int32_t thflags, int32_t nxt_pkt)
5665 {
5666 	int32_t ret_val = 0;
5667 
5668 	rack_calc_rwin(so, tp);
5669 	if (thflags & TH_RST)
5670 		return (rack_process_rst(m, th, so, tp));
5671 	/*
5672 	 * RFC5961 Section 4.2 Send challenge ACK for any SYN in
5673 	 * synchronized state.
5674 	 */
5675 	if (thflags & TH_SYN) {
5676 		rack_challenge_ack(m, th, tp, &ret_val);
5677 		return (ret_val);
5678 	}
5679 	/*
5680 	 * RFC 1323 PAWS: If we have a timestamp reply on this segment and
5681 	 * it's less than ts_recent, drop it.
5682 	 */
5683 	if ((to->to_flags & TOF_TS) != 0 && tp->ts_recent &&
5684 	    TSTMP_LT(to->to_tsval, tp->ts_recent)) {
5685 		if (rack_ts_check(m, th, tp, tlen, thflags, &ret_val))
5686 			return (ret_val);
5687 	}
5688 	if (rack_drop_checks(to, m, th, tp, &tlen, &thflags, &drop_hdrlen, &ret_val)) {
5689 		return (ret_val);
5690 	}
5691 	/*
5692 	 * If last ACK falls within this segment's sequence numbers, record
5693 	 * its timestamp. NOTE: 1) That the test incorporates suggestions
5694 	 * from the latest proposal of the tcplw@cray.com list (Braden
5695 	 * 1993/04/26). 2) That updating only on newer timestamps interferes
5696 	 * with our earlier PAWS tests, so this check should be solely
5697 	 * predicated on the sequence space of this segment. 3) That we
5698 	 * modify the segment boundary check to be Last.ACK.Sent <= SEG.SEQ
5699 	 * + SEG.Len  instead of RFC1323's Last.ACK.Sent < SEG.SEQ +
5700 	 * SEG.Len, This modified check allows us to overcome RFC1323's
5701 	 * limitations as described in Stevens TCP/IP Illustrated Vol. 2
5702 	 * p.869. In such cases, we can still calculate the RTT correctly
5703 	 * when RCV.NXT == Last.ACK.Sent.
5704 	 */
5705 	if ((to->to_flags & TOF_TS) != 0 &&
5706 	    SEQ_LEQ(th->th_seq, tp->last_ack_sent) &&
5707 	    SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen +
5708 	    ((thflags & (TH_SYN | TH_FIN)) != 0))) {
5709 		tp->ts_recent_age = tcp_ts_getticks();
5710 		tp->ts_recent = to->to_tsval;
5711 	}
5712 	/*
5713 	 * If the ACK bit is off:  if in SYN-RECEIVED state or SENDSYN flag
5714 	 * is on (half-synchronized state), then queue data for later
5715 	 * processing; else drop segment and return.
5716 	 */
5717 	if ((thflags & TH_ACK) == 0) {
5718 		if (tp->t_flags & TF_NEEDSYN) {
5719 			return (rack_process_data(m, th, so, tp, drop_hdrlen, tlen,
5720 			    tiwin, thflags, nxt_pkt));
5721 
5722 		} else if (tp->t_flags & TF_ACKNOW) {
5723 			rack_do_dropafterack(m, tp, th, thflags, tlen, &ret_val);
5724 			return (ret_val);
5725 		} else {
5726 			rack_do_drop(m, NULL);
5727 			return (0);
5728 		}
5729 	}
5730 	/*
5731 	 * Ack processing.
5732 	 */
5733 	if (rack_process_ack(m, th, so, tp, to, tiwin, tlen, NULL, thflags, &ret_val)) {
5734 		return (ret_val);
5735 	}
5736 	if (sbavail(&so->so_snd)) {
5737 		if (rack_progress_timeout_check(tp)) {
5738 			tcp_set_inp_to_drop(tp->t_inpcb, ETIMEDOUT);
5739 			rack_do_dropwithreset(m, tp, th, BANDLIM_RST_OPENPORT, tlen);
5740 			return (1);
5741 		}
5742 	}
5743 	return (rack_process_data(m, th, so, tp, drop_hdrlen, tlen,
5744 	    tiwin, thflags, nxt_pkt));
5745 }
5746 
5747 static int
5748 rack_check_data_after_close(struct mbuf *m,
5749     struct tcpcb *tp, int32_t *tlen, struct tcphdr *th, struct socket *so)
5750 {
5751 	struct tcp_rack *rack;
5752 
5753 	INP_INFO_RLOCK_ASSERT(&V_tcbinfo);
5754 	rack = (struct tcp_rack *)tp->t_fb_ptr;
5755 	if (rack->rc_allow_data_af_clo == 0) {
5756 	close_now:
5757 		tp = tcp_close(tp);
5758 		TCPSTAT_INC(tcps_rcvafterclose);
5759 		rack_do_dropwithreset(m, tp, th, BANDLIM_UNLIMITED, (*tlen));
5760 		return (1);
5761 	}
5762 	if (sbavail(&so->so_snd) == 0)
5763 		goto close_now;
5764 	/* Ok we allow data that is ignored and a followup reset */
5765 	tp->rcv_nxt = th->th_seq + *tlen;
5766 	tp->t_flags2 |= TF2_DROP_AF_DATA;
5767 	rack->r_wanted_output = 1;
5768 	*tlen = 0;
5769 	return (0);
5770 }
5771 
5772 /*
5773  * Return value of 1, the TCB is unlocked and most
5774  * likely gone, return value of 0, the TCP is still
5775  * locked.
5776  */
5777 static int
5778 rack_do_fin_wait_1(struct mbuf *m, struct tcphdr *th, struct socket *so,
5779     struct tcpcb *tp, struct tcpopt *to, int32_t drop_hdrlen, int32_t tlen,
5780     uint32_t tiwin, int32_t thflags, int32_t nxt_pkt)
5781 {
5782 	int32_t ret_val = 0;
5783 	int32_t ourfinisacked = 0;
5784 
5785 	rack_calc_rwin(so, tp);
5786 
5787 	if (thflags & TH_RST)
5788 		return (rack_process_rst(m, th, so, tp));
5789 	/*
5790 	 * RFC5961 Section 4.2 Send challenge ACK for any SYN in
5791 	 * synchronized state.
5792 	 */
5793 	if (thflags & TH_SYN) {
5794 		rack_challenge_ack(m, th, tp, &ret_val);
5795 		return (ret_val);
5796 	}
5797 	/*
5798 	 * RFC 1323 PAWS: If we have a timestamp reply on this segment and
5799 	 * it's less than ts_recent, drop it.
5800 	 */
5801 	if ((to->to_flags & TOF_TS) != 0 && tp->ts_recent &&
5802 	    TSTMP_LT(to->to_tsval, tp->ts_recent)) {
5803 		if (rack_ts_check(m, th, tp, tlen, thflags, &ret_val))
5804 			return (ret_val);
5805 	}
5806 	if (rack_drop_checks(to, m, th, tp, &tlen, &thflags, &drop_hdrlen, &ret_val)) {
5807 		return (ret_val);
5808 	}
5809 	/*
5810 	 * If new data are received on a connection after the user processes
5811 	 * are gone, then RST the other end.
5812 	 */
5813 	if ((so->so_state & SS_NOFDREF) && tlen) {
5814 		if (rack_check_data_after_close(m, tp, &tlen, th, so))
5815 			return (1);
5816 	}
5817 	/*
5818 	 * If last ACK falls within this segment's sequence numbers, record
5819 	 * its timestamp. NOTE: 1) That the test incorporates suggestions
5820 	 * from the latest proposal of the tcplw@cray.com list (Braden
5821 	 * 1993/04/26). 2) That updating only on newer timestamps interferes
5822 	 * with our earlier PAWS tests, so this check should be solely
5823 	 * predicated on the sequence space of this segment. 3) That we
5824 	 * modify the segment boundary check to be Last.ACK.Sent <= SEG.SEQ
5825 	 * + SEG.Len  instead of RFC1323's Last.ACK.Sent < SEG.SEQ +
5826 	 * SEG.Len, This modified check allows us to overcome RFC1323's
5827 	 * limitations as described in Stevens TCP/IP Illustrated Vol. 2
5828 	 * p.869. In such cases, we can still calculate the RTT correctly
5829 	 * when RCV.NXT == Last.ACK.Sent.
5830 	 */
5831 	if ((to->to_flags & TOF_TS) != 0 &&
5832 	    SEQ_LEQ(th->th_seq, tp->last_ack_sent) &&
5833 	    SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen +
5834 	    ((thflags & (TH_SYN | TH_FIN)) != 0))) {
5835 		tp->ts_recent_age = tcp_ts_getticks();
5836 		tp->ts_recent = to->to_tsval;
5837 	}
5838 	/*
5839 	 * If the ACK bit is off:  if in SYN-RECEIVED state or SENDSYN flag
5840 	 * is on (half-synchronized state), then queue data for later
5841 	 * processing; else drop segment and return.
5842 	 */
5843 	if ((thflags & TH_ACK) == 0) {
5844 		if (tp->t_flags & TF_NEEDSYN) {
5845 			return (rack_process_data(m, th, so, tp, drop_hdrlen, tlen,
5846 			    tiwin, thflags, nxt_pkt));
5847 		} else if (tp->t_flags & TF_ACKNOW) {
5848 			rack_do_dropafterack(m, tp, th, thflags, tlen, &ret_val);
5849 			return (ret_val);
5850 		} else {
5851 			rack_do_drop(m, NULL);
5852 			return (0);
5853 		}
5854 	}
5855 	/*
5856 	 * Ack processing.
5857 	 */
5858 	if (rack_process_ack(m, th, so, tp, to, tiwin, tlen, &ourfinisacked, thflags, &ret_val)) {
5859 		return (ret_val);
5860 	}
5861 	if (ourfinisacked) {
5862 		/*
5863 		 * If we can't receive any more data, then closing user can
5864 		 * proceed. Starting the timer is contrary to the
5865 		 * specification, but if we don't get a FIN we'll hang
5866 		 * forever.
5867 		 *
5868 		 * XXXjl: we should release the tp also, and use a
5869 		 * compressed state.
5870 		 */
5871 		if (so->so_rcv.sb_state & SBS_CANTRCVMORE) {
5872 			soisdisconnected(so);
5873 			tcp_timer_activate(tp, TT_2MSL,
5874 			    (tcp_fast_finwait2_recycle ?
5875 			    tcp_finwait2_timeout :
5876 			    TP_MAXIDLE(tp)));
5877 		}
5878 		tcp_state_change(tp, TCPS_FIN_WAIT_2);
5879 	}
5880 	if (sbavail(&so->so_snd)) {
5881 		if (rack_progress_timeout_check(tp)) {
5882 			tcp_set_inp_to_drop(tp->t_inpcb, ETIMEDOUT);
5883 			rack_do_dropwithreset(m, tp, th, BANDLIM_RST_OPENPORT, tlen);
5884 			return (1);
5885 		}
5886 	}
5887 	return (rack_process_data(m, th, so, tp, drop_hdrlen, tlen,
5888 	    tiwin, thflags, nxt_pkt));
5889 }
5890 
5891 /*
5892  * Return value of 1, the TCB is unlocked and most
5893  * likely gone, return value of 0, the TCP is still
5894  * locked.
5895  */
5896 static int
5897 rack_do_closing(struct mbuf *m, struct tcphdr *th, struct socket *so,
5898     struct tcpcb *tp, struct tcpopt *to, int32_t drop_hdrlen, int32_t tlen,
5899     uint32_t tiwin, int32_t thflags, int32_t nxt_pkt)
5900 {
5901 	int32_t ret_val = 0;
5902 	int32_t ourfinisacked = 0;
5903 
5904 	rack_calc_rwin(so, tp);
5905 
5906 	if (thflags & TH_RST)
5907 		return (rack_process_rst(m, th, so, tp));
5908 	/*
5909 	 * RFC5961 Section 4.2 Send challenge ACK for any SYN in
5910 	 * synchronized state.
5911 	 */
5912 	if (thflags & TH_SYN) {
5913 		rack_challenge_ack(m, th, tp, &ret_val);
5914 		return (ret_val);
5915 	}
5916 	/*
5917 	 * RFC 1323 PAWS: If we have a timestamp reply on this segment and
5918 	 * it's less than ts_recent, drop it.
5919 	 */
5920 	if ((to->to_flags & TOF_TS) != 0 && tp->ts_recent &&
5921 	    TSTMP_LT(to->to_tsval, tp->ts_recent)) {
5922 		if (rack_ts_check(m, th, tp, tlen, thflags, &ret_val))
5923 			return (ret_val);
5924 	}
5925 	if (rack_drop_checks(to, m, th, tp, &tlen, &thflags, &drop_hdrlen, &ret_val)) {
5926 		return (ret_val);
5927 	}
5928 	/*
5929 	 * If new data are received on a connection after the user processes
5930 	 * are gone, then RST the other end.
5931 	 */
5932 	if ((so->so_state & SS_NOFDREF) && tlen) {
5933 		if (rack_check_data_after_close(m, tp, &tlen, th, so))
5934 			return (1);
5935 	}
5936 	/*
5937 	 * If last ACK falls within this segment's sequence numbers, record
5938 	 * its timestamp. NOTE: 1) That the test incorporates suggestions
5939 	 * from the latest proposal of the tcplw@cray.com list (Braden
5940 	 * 1993/04/26). 2) That updating only on newer timestamps interferes
5941 	 * with our earlier PAWS tests, so this check should be solely
5942 	 * predicated on the sequence space of this segment. 3) That we
5943 	 * modify the segment boundary check to be Last.ACK.Sent <= SEG.SEQ
5944 	 * + SEG.Len  instead of RFC1323's Last.ACK.Sent < SEG.SEQ +
5945 	 * SEG.Len, This modified check allows us to overcome RFC1323's
5946 	 * limitations as described in Stevens TCP/IP Illustrated Vol. 2
5947 	 * p.869. In such cases, we can still calculate the RTT correctly
5948 	 * when RCV.NXT == Last.ACK.Sent.
5949 	 */
5950 	if ((to->to_flags & TOF_TS) != 0 &&
5951 	    SEQ_LEQ(th->th_seq, tp->last_ack_sent) &&
5952 	    SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen +
5953 	    ((thflags & (TH_SYN | TH_FIN)) != 0))) {
5954 		tp->ts_recent_age = tcp_ts_getticks();
5955 		tp->ts_recent = to->to_tsval;
5956 	}
5957 	/*
5958 	 * If the ACK bit is off:  if in SYN-RECEIVED state or SENDSYN flag
5959 	 * is on (half-synchronized state), then queue data for later
5960 	 * processing; else drop segment and return.
5961 	 */
5962 	if ((thflags & TH_ACK) == 0) {
5963 		if (tp->t_flags & TF_NEEDSYN) {
5964 			return (rack_process_data(m, th, so, tp, drop_hdrlen, tlen,
5965 			    tiwin, thflags, nxt_pkt));
5966 		} else if (tp->t_flags & TF_ACKNOW) {
5967 			rack_do_dropafterack(m, tp, th, thflags, tlen, &ret_val);
5968 			return (ret_val);
5969 		} else {
5970 			rack_do_drop(m, NULL);
5971 			return (0);
5972 		}
5973 	}
5974 	/*
5975 	 * Ack processing.
5976 	 */
5977 	if (rack_process_ack(m, th, so, tp, to, tiwin, tlen, &ourfinisacked, thflags, &ret_val)) {
5978 		return (ret_val);
5979 	}
5980 	if (ourfinisacked) {
5981 		INP_INFO_RLOCK_ASSERT(&V_tcbinfo);
5982 		tcp_twstart(tp);
5983 		m_freem(m);
5984 		return (1);
5985 	}
5986 	if (sbavail(&so->so_snd)) {
5987 		if (rack_progress_timeout_check(tp)) {
5988 			tcp_set_inp_to_drop(tp->t_inpcb, ETIMEDOUT);
5989 			rack_do_dropwithreset(m, tp, th, BANDLIM_RST_OPENPORT, tlen);
5990 			return (1);
5991 		}
5992 	}
5993 	return (rack_process_data(m, th, so, tp, drop_hdrlen, tlen,
5994 	    tiwin, thflags, nxt_pkt));
5995 }
5996 
5997 /*
5998  * Return value of 1, the TCB is unlocked and most
5999  * likely gone, return value of 0, the TCP is still
6000  * locked.
6001  */
6002 static int
6003 rack_do_lastack(struct mbuf *m, struct tcphdr *th, struct socket *so,
6004     struct tcpcb *tp, struct tcpopt *to, int32_t drop_hdrlen, int32_t tlen,
6005     uint32_t tiwin, int32_t thflags, int32_t nxt_pkt)
6006 {
6007 	int32_t ret_val = 0;
6008 	int32_t ourfinisacked = 0;
6009 
6010 	rack_calc_rwin(so, tp);
6011 
6012 	if (thflags & TH_RST)
6013 		return (rack_process_rst(m, th, so, tp));
6014 	/*
6015 	 * RFC5961 Section 4.2 Send challenge ACK for any SYN in
6016 	 * synchronized state.
6017 	 */
6018 	if (thflags & TH_SYN) {
6019 		rack_challenge_ack(m, th, tp, &ret_val);
6020 		return (ret_val);
6021 	}
6022 	/*
6023 	 * RFC 1323 PAWS: If we have a timestamp reply on this segment and
6024 	 * it's less than ts_recent, drop it.
6025 	 */
6026 	if ((to->to_flags & TOF_TS) != 0 && tp->ts_recent &&
6027 	    TSTMP_LT(to->to_tsval, tp->ts_recent)) {
6028 		if (rack_ts_check(m, th, tp, tlen, thflags, &ret_val))
6029 			return (ret_val);
6030 	}
6031 	if (rack_drop_checks(to, m, th, tp, &tlen, &thflags, &drop_hdrlen, &ret_val)) {
6032 		return (ret_val);
6033 	}
6034 	/*
6035 	 * If new data are received on a connection after the user processes
6036 	 * are gone, then RST the other end.
6037 	 */
6038 	if ((so->so_state & SS_NOFDREF) && tlen) {
6039 		if (rack_check_data_after_close(m, tp, &tlen, th, so))
6040 			return (1);
6041 	}
6042 	/*
6043 	 * If last ACK falls within this segment's sequence numbers, record
6044 	 * its timestamp. NOTE: 1) That the test incorporates suggestions
6045 	 * from the latest proposal of the tcplw@cray.com list (Braden
6046 	 * 1993/04/26). 2) That updating only on newer timestamps interferes
6047 	 * with our earlier PAWS tests, so this check should be solely
6048 	 * predicated on the sequence space of this segment. 3) That we
6049 	 * modify the segment boundary check to be Last.ACK.Sent <= SEG.SEQ
6050 	 * + SEG.Len  instead of RFC1323's Last.ACK.Sent < SEG.SEQ +
6051 	 * SEG.Len, This modified check allows us to overcome RFC1323's
6052 	 * limitations as described in Stevens TCP/IP Illustrated Vol. 2
6053 	 * p.869. In such cases, we can still calculate the RTT correctly
6054 	 * when RCV.NXT == Last.ACK.Sent.
6055 	 */
6056 	if ((to->to_flags & TOF_TS) != 0 &&
6057 	    SEQ_LEQ(th->th_seq, tp->last_ack_sent) &&
6058 	    SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen +
6059 	    ((thflags & (TH_SYN | TH_FIN)) != 0))) {
6060 		tp->ts_recent_age = tcp_ts_getticks();
6061 		tp->ts_recent = to->to_tsval;
6062 	}
6063 	/*
6064 	 * If the ACK bit is off:  if in SYN-RECEIVED state or SENDSYN flag
6065 	 * is on (half-synchronized state), then queue data for later
6066 	 * processing; else drop segment and return.
6067 	 */
6068 	if ((thflags & TH_ACK) == 0) {
6069 		if (tp->t_flags & TF_NEEDSYN) {
6070 			return (rack_process_data(m, th, so, tp, drop_hdrlen, tlen,
6071 			    tiwin, thflags, nxt_pkt));
6072 		} else if (tp->t_flags & TF_ACKNOW) {
6073 			rack_do_dropafterack(m, tp, th, thflags, tlen, &ret_val);
6074 			return (ret_val);
6075 		} else {
6076 			rack_do_drop(m, NULL);
6077 			return (0);
6078 		}
6079 	}
6080 	/*
6081 	 * case TCPS_LAST_ACK: Ack processing.
6082 	 */
6083 	if (rack_process_ack(m, th, so, tp, to, tiwin, tlen, &ourfinisacked, thflags, &ret_val)) {
6084 		return (ret_val);
6085 	}
6086 	if (ourfinisacked) {
6087 		INP_INFO_RLOCK_ASSERT(&V_tcbinfo);
6088 		tp = tcp_close(tp);
6089 		rack_do_drop(m, tp);
6090 		return (1);
6091 	}
6092 	if (sbavail(&so->so_snd)) {
6093 		if (rack_progress_timeout_check(tp)) {
6094 			tcp_set_inp_to_drop(tp->t_inpcb, ETIMEDOUT);
6095 			rack_do_dropwithreset(m, tp, th, BANDLIM_RST_OPENPORT, tlen);
6096 			return (1);
6097 		}
6098 	}
6099 	return (rack_process_data(m, th, so, tp, drop_hdrlen, tlen,
6100 	    tiwin, thflags, nxt_pkt));
6101 }
6102 
6103 
6104 /*
6105  * Return value of 1, the TCB is unlocked and most
6106  * likely gone, return value of 0, the TCP is still
6107  * locked.
6108  */
6109 static int
6110 rack_do_fin_wait_2(struct mbuf *m, struct tcphdr *th, struct socket *so,
6111     struct tcpcb *tp, struct tcpopt *to, int32_t drop_hdrlen, int32_t tlen,
6112     uint32_t tiwin, int32_t thflags, int32_t nxt_pkt)
6113 {
6114 	int32_t ret_val = 0;
6115 	int32_t ourfinisacked = 0;
6116 
6117 	rack_calc_rwin(so, tp);
6118 
6119 	/* Reset receive buffer auto scaling when not in bulk receive mode. */
6120 	if (thflags & TH_RST)
6121 		return (rack_process_rst(m, th, so, tp));
6122 	/*
6123 	 * RFC5961 Section 4.2 Send challenge ACK for any SYN in
6124 	 * synchronized state.
6125 	 */
6126 	if (thflags & TH_SYN) {
6127 		rack_challenge_ack(m, th, tp, &ret_val);
6128 		return (ret_val);
6129 	}
6130 	/*
6131 	 * RFC 1323 PAWS: If we have a timestamp reply on this segment and
6132 	 * it's less than ts_recent, drop it.
6133 	 */
6134 	if ((to->to_flags & TOF_TS) != 0 && tp->ts_recent &&
6135 	    TSTMP_LT(to->to_tsval, tp->ts_recent)) {
6136 		if (rack_ts_check(m, th, tp, tlen, thflags, &ret_val))
6137 			return (ret_val);
6138 	}
6139 	if (rack_drop_checks(to, m, th, tp, &tlen, &thflags, &drop_hdrlen, &ret_val)) {
6140 		return (ret_val);
6141 	}
6142 	/*
6143 	 * If new data are received on a connection after the user processes
6144 	 * are gone, then RST the other end.
6145 	 */
6146 	if ((so->so_state & SS_NOFDREF) &&
6147 	    tlen) {
6148 		if (rack_check_data_after_close(m, tp, &tlen, th, so))
6149 			return (1);
6150 	}
6151 	/*
6152 	 * If last ACK falls within this segment's sequence numbers, record
6153 	 * its timestamp. NOTE: 1) That the test incorporates suggestions
6154 	 * from the latest proposal of the tcplw@cray.com list (Braden
6155 	 * 1993/04/26). 2) That updating only on newer timestamps interferes
6156 	 * with our earlier PAWS tests, so this check should be solely
6157 	 * predicated on the sequence space of this segment. 3) That we
6158 	 * modify the segment boundary check to be Last.ACK.Sent <= SEG.SEQ
6159 	 * + SEG.Len  instead of RFC1323's Last.ACK.Sent < SEG.SEQ +
6160 	 * SEG.Len, This modified check allows us to overcome RFC1323's
6161 	 * limitations as described in Stevens TCP/IP Illustrated Vol. 2
6162 	 * p.869. In such cases, we can still calculate the RTT correctly
6163 	 * when RCV.NXT == Last.ACK.Sent.
6164 	 */
6165 	if ((to->to_flags & TOF_TS) != 0 &&
6166 	    SEQ_LEQ(th->th_seq, tp->last_ack_sent) &&
6167 	    SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen +
6168 	    ((thflags & (TH_SYN | TH_FIN)) != 0))) {
6169 		tp->ts_recent_age = tcp_ts_getticks();
6170 		tp->ts_recent = to->to_tsval;
6171 	}
6172 	/*
6173 	 * If the ACK bit is off:  if in SYN-RECEIVED state or SENDSYN flag
6174 	 * is on (half-synchronized state), then queue data for later
6175 	 * processing; else drop segment and return.
6176 	 */
6177 	if ((thflags & TH_ACK) == 0) {
6178 		if (tp->t_flags & TF_NEEDSYN) {
6179 			return (rack_process_data(m, th, so, tp, drop_hdrlen, tlen,
6180 			    tiwin, thflags, nxt_pkt));
6181 		} else if (tp->t_flags & TF_ACKNOW) {
6182 			rack_do_dropafterack(m, tp, th, thflags, tlen, &ret_val);
6183 			return (ret_val);
6184 		} else {
6185 			rack_do_drop(m, NULL);
6186 			return (0);
6187 		}
6188 	}
6189 	/*
6190 	 * Ack processing.
6191 	 */
6192 	if (rack_process_ack(m, th, so, tp, to, tiwin, tlen, &ourfinisacked, thflags, &ret_val)) {
6193 		return (ret_val);
6194 	}
6195 	if (sbavail(&so->so_snd)) {
6196 		if (rack_progress_timeout_check(tp)) {
6197 			tcp_set_inp_to_drop(tp->t_inpcb, ETIMEDOUT);
6198 			rack_do_dropwithreset(m, tp, th, BANDLIM_RST_OPENPORT, tlen);
6199 			return (1);
6200 		}
6201 	}
6202 	return (rack_process_data(m, th, so, tp, drop_hdrlen, tlen,
6203 	    tiwin, thflags, nxt_pkt));
6204 }
6205 
6206 
6207 static void inline
6208 rack_clear_rate_sample(struct tcp_rack *rack)
6209 {
6210 	rack->r_ctl.rack_rs.rs_flags = RACK_RTT_EMPTY;
6211 	rack->r_ctl.rack_rs.rs_rtt_cnt = 0;
6212 	rack->r_ctl.rack_rs.rs_rtt_tot = 0;
6213 }
6214 
6215 static int
6216 rack_init(struct tcpcb *tp)
6217 {
6218 	struct tcp_rack *rack = NULL;
6219 
6220 	tp->t_fb_ptr = uma_zalloc(rack_pcb_zone, M_NOWAIT);
6221 	if (tp->t_fb_ptr == NULL) {
6222 		/*
6223 		 * We need to allocate memory but cant. The INP and INP_INFO
6224 		 * locks and they are recusive (happens during setup. So a
6225 		 * scheme to drop the locks fails :(
6226 		 *
6227 		 */
6228 		return (ENOMEM);
6229 	}
6230 	memset(tp->t_fb_ptr, 0, sizeof(struct tcp_rack));
6231 
6232 	rack = (struct tcp_rack *)tp->t_fb_ptr;
6233 	TAILQ_INIT(&rack->r_ctl.rc_map);
6234 	TAILQ_INIT(&rack->r_ctl.rc_free);
6235 	TAILQ_INIT(&rack->r_ctl.rc_tmap);
6236 	rack->rc_tp = tp;
6237 	if (tp->t_inpcb) {
6238 		rack->rc_inp = tp->t_inpcb;
6239 	}
6240 	/* Probably not needed but lets be sure */
6241 	rack_clear_rate_sample(rack);
6242 	rack->r_cpu = 0;
6243 	rack->r_ctl.rc_reorder_fade = rack_reorder_fade;
6244 	rack->rc_allow_data_af_clo = rack_ignore_data_after_close;
6245 	rack->r_ctl.rc_tlp_threshold = rack_tlp_thresh;
6246 	rack->rc_pace_reduce = rack_slot_reduction;
6247 	if (V_tcp_delack_enabled)
6248 		tp->t_delayed_ack = 1;
6249 	else
6250 		tp->t_delayed_ack = 0;
6251 	rack->rc_pace_max_segs = rack_hptsi_segments;
6252 	rack->r_ctl.rc_early_recovery_segs = rack_early_recovery_max_seg;
6253 	rack->r_ctl.rc_reorder_shift = rack_reorder_thresh;
6254 	rack->r_ctl.rc_pkt_delay = rack_pkt_delay;
6255 	rack->r_ctl.rc_prop_reduce = rack_use_proportional_reduce;
6256 	rack->r_idle_reduce_largest  = rack_reduce_largest_on_idle;
6257 	rack->r_enforce_min_pace = rack_min_pace_time;
6258 	rack->r_min_pace_seg_thresh = rack_min_pace_time_seg_req;
6259 	rack->r_ctl.rc_prop_rate = rack_proportional_rate;
6260 	rack->r_ctl.rc_tlp_cwnd_reduce = rack_lower_cwnd_at_tlp;
6261 	rack->r_ctl.rc_early_recovery = rack_early_recovery;
6262 	rack->rc_always_pace = rack_pace_every_seg;
6263 	rack->r_ctl.rc_rate_sample_method = rack_rate_sample_method;
6264 	rack->rack_tlp_threshold_use = rack_tlp_threshold_use;
6265 	rack->r_ctl.rc_prr_sendalot = rack_send_a_lot_in_prr;
6266 	rack->r_ctl.rc_min_to = rack_min_to;
6267 	rack->r_ctl.rc_prr_inc_var = rack_inc_var;
6268 	rack_start_hpts_timer(rack, tp, tcp_ts_getticks(), __LINE__, 0, 0, 0);
6269 	if (tp->snd_una != tp->snd_max) {
6270 		/* Create a send map for the current outstanding data */
6271 		struct rack_sendmap *rsm;
6272 
6273 		rsm = rack_alloc(rack);
6274 		if (rsm == NULL) {
6275 			uma_zfree(rack_pcb_zone, tp->t_fb_ptr);
6276 			tp->t_fb_ptr = NULL;
6277 			return (ENOMEM);
6278 		}
6279 		rsm->r_flags = RACK_OVERMAX;
6280 		rsm->r_tim_lastsent[0] = tcp_ts_getticks();
6281 		rsm->r_rtr_cnt = 1;
6282 		rsm->r_rtr_bytes = 0;
6283 		rsm->r_start = tp->snd_una;
6284 		rsm->r_end = tp->snd_max;
6285 		rsm->r_sndcnt = 0;
6286 		TAILQ_INSERT_TAIL(&rack->r_ctl.rc_map, rsm, r_next);
6287 		TAILQ_INSERT_TAIL(&rack->r_ctl.rc_tmap, rsm, r_tnext);
6288 		rsm->r_in_tmap = 1;
6289 	}
6290 	return (0);
6291 }
6292 
6293 static int
6294 rack_handoff_ok(struct tcpcb *tp)
6295 {
6296 	if ((tp->t_state == TCPS_CLOSED) ||
6297 	    (tp->t_state == TCPS_LISTEN)) {
6298 		/* Sure no problem though it may not stick */
6299 		return (0);
6300 	}
6301 	if ((tp->t_state == TCPS_SYN_SENT) ||
6302 	    (tp->t_state == TCPS_SYN_RECEIVED)) {
6303 		/*
6304 		 * We really don't know you have to get to ESTAB or beyond
6305 		 * to tell.
6306 		 */
6307 		return (EAGAIN);
6308 	}
6309 	if (tp->t_flags & TF_SACK_PERMIT) {
6310 		return (0);
6311 	}
6312 	/*
6313 	 * If we reach here we don't do SACK on this connection so we can
6314 	 * never do rack.
6315 	 */
6316 	return (EINVAL);
6317 }
6318 
6319 static void
6320 rack_fini(struct tcpcb *tp, int32_t tcb_is_purged)
6321 {
6322 	if (tp->t_fb_ptr) {
6323 		struct tcp_rack *rack;
6324 		struct rack_sendmap *rsm;
6325 
6326 		rack = (struct tcp_rack *)tp->t_fb_ptr;
6327 #ifdef TCP_BLACKBOX
6328 		tcp_log_flowend(tp);
6329 #endif
6330 		rsm = TAILQ_FIRST(&rack->r_ctl.rc_map);
6331 		while (rsm) {
6332 			TAILQ_REMOVE(&rack->r_ctl.rc_map, rsm, r_next);
6333 			uma_zfree(rack_zone, rsm);
6334 			rsm = TAILQ_FIRST(&rack->r_ctl.rc_map);
6335 		}
6336 		rsm = TAILQ_FIRST(&rack->r_ctl.rc_free);
6337 		while (rsm) {
6338 			TAILQ_REMOVE(&rack->r_ctl.rc_free, rsm, r_next);
6339 			uma_zfree(rack_zone, rsm);
6340 			rsm = TAILQ_FIRST(&rack->r_ctl.rc_free);
6341 		}
6342 		rack->rc_free_cnt = 0;
6343 		uma_zfree(rack_pcb_zone, tp->t_fb_ptr);
6344 		tp->t_fb_ptr = NULL;
6345 	}
6346 }
6347 
6348 static void
6349 rack_set_state(struct tcpcb *tp, struct tcp_rack *rack)
6350 {
6351 	switch (tp->t_state) {
6352 	case TCPS_SYN_SENT:
6353 		rack->r_state = TCPS_SYN_SENT;
6354 		rack->r_substate = rack_do_syn_sent;
6355 		break;
6356 	case TCPS_SYN_RECEIVED:
6357 		rack->r_state = TCPS_SYN_RECEIVED;
6358 		rack->r_substate = rack_do_syn_recv;
6359 		break;
6360 	case TCPS_ESTABLISHED:
6361 		rack->r_state = TCPS_ESTABLISHED;
6362 		rack->r_substate = rack_do_established;
6363 		break;
6364 	case TCPS_CLOSE_WAIT:
6365 		rack->r_state = TCPS_CLOSE_WAIT;
6366 		rack->r_substate = rack_do_close_wait;
6367 		break;
6368 	case TCPS_FIN_WAIT_1:
6369 		rack->r_state = TCPS_FIN_WAIT_1;
6370 		rack->r_substate = rack_do_fin_wait_1;
6371 		break;
6372 	case TCPS_CLOSING:
6373 		rack->r_state = TCPS_CLOSING;
6374 		rack->r_substate = rack_do_closing;
6375 		break;
6376 	case TCPS_LAST_ACK:
6377 		rack->r_state = TCPS_LAST_ACK;
6378 		rack->r_substate = rack_do_lastack;
6379 		break;
6380 	case TCPS_FIN_WAIT_2:
6381 		rack->r_state = TCPS_FIN_WAIT_2;
6382 		rack->r_substate = rack_do_fin_wait_2;
6383 		break;
6384 	case TCPS_LISTEN:
6385 	case TCPS_CLOSED:
6386 	case TCPS_TIME_WAIT:
6387 	default:
6388 #ifdef INVARIANTS
6389 		panic("tcp tp:%p state:%d sees impossible state?", tp, tp->t_state);
6390 #endif
6391 		break;
6392 	};
6393 }
6394 
6395 
6396 static void
6397 rack_timer_audit(struct tcpcb *tp, struct tcp_rack *rack, struct sockbuf *sb)
6398 {
6399 	/*
6400 	 * We received an ack, and then did not
6401 	 * call send or were bounced out due to the
6402 	 * hpts was running. Now a timer is up as well, is
6403 	 * it the right timer?
6404 	 */
6405 	struct rack_sendmap *rsm;
6406 	int tmr_up;
6407 
6408 	tmr_up = rack->r_ctl.rc_hpts_flags & PACE_TMR_MASK;
6409 	if (rack->rc_in_persist && (tmr_up == PACE_TMR_PERSIT))
6410 		return;
6411 	rsm = TAILQ_FIRST(&rack->r_ctl.rc_tmap);
6412 	if (((rsm == NULL) || (tp->t_state < TCPS_ESTABLISHED)) &&
6413 	    (tmr_up == PACE_TMR_RXT)) {
6414 		/* Should be an RXT */
6415 		return;
6416 	}
6417 	if (rsm == NULL) {
6418 		/* Nothing outstanding? */
6419 		if (tp->t_flags & TF_DELACK) {
6420 			if (tmr_up == PACE_TMR_DELACK)
6421 				/* We are supposed to have delayed ack up and we do */
6422 				return;
6423 		} else if (sbavail(&tp->t_inpcb->inp_socket->so_snd) && (tmr_up == PACE_TMR_RXT)) {
6424 			/*
6425 			 * if we hit enobufs then we would expect the possiblity
6426 			 * of nothing outstanding and the RXT up (and the hptsi timer).
6427 			 */
6428 			return;
6429 		} else if (((tcp_always_keepalive ||
6430 			     rack->rc_inp->inp_socket->so_options & SO_KEEPALIVE) &&
6431 			    (tp->t_state <= TCPS_CLOSING)) &&
6432 			   (tmr_up == PACE_TMR_KEEP) &&
6433 			   (tp->snd_max == tp->snd_una)) {
6434 			/* We should have keep alive up and we do */
6435 			return;
6436 		}
6437 	}
6438 	if (rsm && (rsm->r_flags & RACK_SACK_PASSED)) {
6439 		if ((tp->t_flags & TF_SENTFIN) &&
6440 		    ((tp->snd_max - tp->snd_una) == 1) &&
6441 		    (rsm->r_flags & RACK_HAS_FIN)) {
6442 			/* needs to be a RXT */
6443 			if (tmr_up == PACE_TMR_RXT)
6444 				return;
6445 		} else if (tmr_up == PACE_TMR_RACK)
6446 			return;
6447 	} else if (SEQ_GT(tp->snd_max,tp->snd_una) &&
6448 		   ((tmr_up == PACE_TMR_TLP) ||
6449 		    (tmr_up == PACE_TMR_RXT))) {
6450 		/*
6451 		 * Either a TLP or RXT is fine if no sack-passed
6452 		 * is in place and data is outstanding.
6453 		 */
6454 		return;
6455 	} else if (tmr_up == PACE_TMR_DELACK) {
6456 		/*
6457 		 * If the delayed ack was going to go off
6458 		 * before the rtx/tlp/rack timer were going to
6459 		 * expire, then that would be the timer in control.
6460 		 * Note we don't check the time here trusting the
6461 		 * code is correct.
6462 		 */
6463 		return;
6464 	}
6465 	/*
6466 	 * Ok the timer originally started is not what we want now.
6467 	 * We will force the hpts to be stopped if any, and restart
6468 	 * with the slot set to what was in the saved slot.
6469 	 */
6470 	rack_timer_cancel(tp, rack, rack->r_ctl.rc_rcvtime, __LINE__);
6471 	rack_start_hpts_timer(rack, tp, tcp_ts_getticks(), __LINE__, 0, 0, 0);
6472 }
6473 
6474 static void
6475 rack_hpts_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
6476     struct tcpcb *tp, int32_t drop_hdrlen, int32_t tlen, uint8_t iptos,
6477     int32_t nxt_pkt, struct timeval *tv)
6478 {
6479 	int32_t thflags, retval, did_out = 0;
6480 	int32_t way_out = 0;
6481 	uint32_t cts;
6482 	uint32_t tiwin;
6483 	struct tcpopt to;
6484 	struct tcp_rack *rack;
6485 	struct rack_sendmap *rsm;
6486 	int32_t prev_state = 0;
6487 
6488 	cts = tcp_tv_to_mssectick(tv);
6489 	rack = (struct tcp_rack *)tp->t_fb_ptr;
6490 
6491 	kern_prefetch(rack, &prev_state);
6492 	prev_state = 0;
6493 	thflags = th->th_flags;
6494 	/*
6495 	 * If this is either a state-changing packet or current state isn't
6496 	 * established, we require a read lock on tcbinfo.  Otherwise, we
6497 	 * allow the tcbinfo to be in either locked or unlocked, as the
6498 	 * caller may have unnecessarily acquired a lock due to a race.
6499 	 */
6500 	if ((thflags & (TH_SYN | TH_FIN | TH_RST)) != 0 ||
6501 	    tp->t_state != TCPS_ESTABLISHED) {
6502 		INP_INFO_RLOCK_ASSERT(&V_tcbinfo);
6503 	}
6504 	INP_WLOCK_ASSERT(tp->t_inpcb);
6505 	KASSERT(tp->t_state > TCPS_LISTEN, ("%s: TCPS_LISTEN",
6506 	    __func__));
6507 	KASSERT(tp->t_state != TCPS_TIME_WAIT, ("%s: TCPS_TIME_WAIT",
6508 	    __func__));
6509 	{
6510 		union tcp_log_stackspecific log;
6511 
6512 		memset(&log.u_bbr, 0, sizeof(log.u_bbr));
6513 		log.u_bbr.inhpts = rack->rc_inp->inp_in_hpts;
6514 		log.u_bbr.ininput = rack->rc_inp->inp_in_input;
6515 		TCP_LOG_EVENT(tp, th, &so->so_rcv, &so->so_snd, TCP_LOG_IN, 0,
6516 		    tlen, &log, true);
6517 	}
6518 	if ((thflags & TH_SYN) && (thflags & TH_FIN) && V_drop_synfin) {
6519 		way_out = 4;
6520 		goto done_with_input;
6521 	}
6522 	/*
6523 	 * If a segment with the ACK-bit set arrives in the SYN-SENT state
6524 	 * check SEQ.ACK first as described on page 66 of RFC 793, section 3.9.
6525 	 */
6526 	if ((tp->t_state == TCPS_SYN_SENT) && (thflags & TH_ACK) &&
6527 	    (SEQ_LEQ(th->th_ack, tp->iss) || SEQ_GT(th->th_ack, tp->snd_max))) {
6528 		rack_do_dropwithreset(m, tp, th, BANDLIM_RST_OPENPORT, tlen);
6529 		return;
6530 	}
6531 	/*
6532 	 * Segment received on connection. Reset idle time and keep-alive
6533 	 * timer. XXX: This should be done after segment validation to
6534 	 * ignore broken/spoofed segs.
6535 	 */
6536 	if  (tp->t_idle_reduce && (tp->snd_max == tp->snd_una)) {
6537 #ifdef NETFLIX_CWV
6538 		if ((tp->cwv_enabled) &&
6539 		    ((tp->cwv_cwnd_valid == 0) &&
6540 		     TCPS_HAVEESTABLISHED(tp->t_state) &&
6541 		     (tp->snd_cwnd > tp->snd_cwv.init_cwnd))) {
6542 			tcp_newcwv_nvp_closedown(tp);
6543 		} else
6544 #endif
6545 		       if ((ticks - tp->t_rcvtime) >= tp->t_rxtcur) {
6546 			counter_u64_add(rack_input_idle_reduces, 1);
6547 			rack_cc_after_idle(tp,
6548 			    (rack->r_idle_reduce_largest ? 1 :0));
6549 		}
6550 	}
6551 	rack->r_ctl.rc_rcvtime = cts;
6552 	tp->t_rcvtime = ticks;
6553 
6554 #ifdef NETFLIX_CWV
6555 	if (tp->cwv_enabled) {
6556 		if ((tp->cwv_cwnd_valid == 0) &&
6557 		    TCPS_HAVEESTABLISHED(tp->t_state) &&
6558 		    (tp->snd_cwnd > tp->snd_cwv.init_cwnd))
6559 			tcp_newcwv_nvp_closedown(tp);
6560 	}
6561 #endif
6562 	/*
6563 	 * Unscale the window into a 32-bit value. For the SYN_SENT state
6564 	 * the scale is zero.
6565 	 */
6566 	tiwin = th->th_win << tp->snd_scale;
6567 #ifdef NETFLIX_STATS
6568 	stats_voi_update_abs_ulong(tp->t_stats, VOI_TCP_FRWIN, tiwin);
6569 #endif
6570 	/*
6571 	 * TCP ECN processing. XXXJTL: If we ever use ECN, we need to move
6572 	 * this to occur after we've validated the segment.
6573 	 */
6574 	if (tp->t_flags & TF_ECN_PERMIT) {
6575 		if (thflags & TH_CWR)
6576 			tp->t_flags &= ~TF_ECN_SND_ECE;
6577 		switch (iptos & IPTOS_ECN_MASK) {
6578 		case IPTOS_ECN_CE:
6579 			tp->t_flags |= TF_ECN_SND_ECE;
6580 			TCPSTAT_INC(tcps_ecn_ce);
6581 			break;
6582 		case IPTOS_ECN_ECT0:
6583 			TCPSTAT_INC(tcps_ecn_ect0);
6584 			break;
6585 		case IPTOS_ECN_ECT1:
6586 			TCPSTAT_INC(tcps_ecn_ect1);
6587 			break;
6588 		}
6589 		/* Congestion experienced. */
6590 		if (thflags & TH_ECE) {
6591 			rack_cong_signal(tp, th, CC_ECN);
6592 		}
6593 	}
6594 	/*
6595 	 * Parse options on any incoming segment.
6596 	 */
6597 	tcp_dooptions(&to, (u_char *)(th + 1),
6598 	    (th->th_off << 2) - sizeof(struct tcphdr),
6599 	    (thflags & TH_SYN) ? TO_SYN : 0);
6600 
6601 	/*
6602 	 * If echoed timestamp is later than the current time, fall back to
6603 	 * non RFC1323 RTT calculation.  Normalize timestamp if syncookies
6604 	 * were used when this connection was established.
6605 	 */
6606 	if ((to.to_flags & TOF_TS) && (to.to_tsecr != 0)) {
6607 		to.to_tsecr -= tp->ts_offset;
6608 		if (TSTMP_GT(to.to_tsecr, cts))
6609 			to.to_tsecr = 0;
6610 	}
6611 	/*
6612 	 * If its the first time in we need to take care of options and
6613 	 * verify we can do SACK for rack!
6614 	 */
6615 	if (rack->r_state == 0) {
6616 		/* Should be init'd by rack_init() */
6617 		KASSERT(rack->rc_inp != NULL,
6618 		    ("%s: rack->rc_inp unexpectedly NULL", __func__));
6619 		if (rack->rc_inp == NULL) {
6620 			rack->rc_inp = tp->t_inpcb;
6621 		}
6622 
6623 		/*
6624 		 * Process options only when we get SYN/ACK back. The SYN
6625 		 * case for incoming connections is handled in tcp_syncache.
6626 		 * According to RFC1323 the window field in a SYN (i.e., a
6627 		 * <SYN> or <SYN,ACK>) segment itself is never scaled. XXX
6628 		 * this is traditional behavior, may need to be cleaned up.
6629 		 */
6630 		rack->r_cpu = inp_to_cpuid(tp->t_inpcb);
6631 		if (tp->t_state == TCPS_SYN_SENT && (thflags & TH_SYN)) {
6632 			if ((to.to_flags & TOF_SCALE) &&
6633 			    (tp->t_flags & TF_REQ_SCALE)) {
6634 				tp->t_flags |= TF_RCVD_SCALE;
6635 				tp->snd_scale = to.to_wscale;
6636 			}
6637 			/*
6638 			 * Initial send window.  It will be updated with the
6639 			 * next incoming segment to the scaled value.
6640 			 */
6641 			tp->snd_wnd = th->th_win;
6642 			if (to.to_flags & TOF_TS) {
6643 				tp->t_flags |= TF_RCVD_TSTMP;
6644 				tp->ts_recent = to.to_tsval;
6645 				tp->ts_recent_age = cts;
6646 			}
6647 			if (to.to_flags & TOF_MSS)
6648 				tcp_mss(tp, to.to_mss);
6649 			if ((tp->t_flags & TF_SACK_PERMIT) &&
6650 			    (to.to_flags & TOF_SACKPERM) == 0)
6651 				tp->t_flags &= ~TF_SACK_PERMIT;
6652 			if (IS_FASTOPEN(tp->t_flags)) {
6653 				if (to.to_flags & TOF_FASTOPEN) {
6654 					uint16_t mss;
6655 
6656 					if (to.to_flags & TOF_MSS)
6657 						mss = to.to_mss;
6658 					else
6659 						if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0)
6660 							mss = TCP6_MSS;
6661 						else
6662 							mss = TCP_MSS;
6663 					tcp_fastopen_update_cache(tp, mss,
6664 					    to.to_tfo_len, to.to_tfo_cookie);
6665 				} else
6666 					tcp_fastopen_disable_path(tp);
6667 			}
6668 		}
6669 		/*
6670 		 * At this point we are at the initial call. Here we decide
6671 		 * if we are doing RACK or not. We do this by seeing if
6672 		 * TF_SACK_PERMIT is set, if not rack is *not* possible and
6673 		 * we switch to the default code.
6674 		 */
6675 		if ((tp->t_flags & TF_SACK_PERMIT) == 0) {
6676 			tcp_switch_back_to_default(tp);
6677 			(*tp->t_fb->tfb_tcp_do_segment) (m, th, so, tp, drop_hdrlen,
6678 			    tlen, iptos);
6679 			return;
6680 		}
6681 		/* Set the flag */
6682 		rack->r_is_v6 = (tp->t_inpcb->inp_vflag & INP_IPV6) != 0;
6683 		tcp_set_hpts(tp->t_inpcb);
6684 		rack_stop_all_timers(tp);
6685 		sack_filter_clear(&rack->r_ctl.rack_sf, th->th_ack);
6686 	}
6687 	/*
6688 	 * This is the one exception case where we set the rack state
6689 	 * always. All other times (timers etc) we must have a rack-state
6690 	 * set (so we assure we have done the checks above for SACK).
6691 	 */
6692 	if (rack->r_state != tp->t_state)
6693 		rack_set_state(tp, rack);
6694 	if (SEQ_GT(th->th_ack, tp->snd_una) && (rsm = TAILQ_FIRST(&rack->r_ctl.rc_map)) != NULL)
6695 		kern_prefetch(rsm, &prev_state);
6696 	prev_state = rack->r_state;
6697 	rack->r_ctl.rc_tlp_send_cnt = 0;
6698 	rack_clear_rate_sample(rack);
6699 	retval = (*rack->r_substate) (m, th, so,
6700 	    tp, &to, drop_hdrlen,
6701 	    tlen, tiwin, thflags, nxt_pkt);
6702 #ifdef INVARIANTS
6703 	if ((retval == 0) &&
6704 	    (tp->t_inpcb == NULL)) {
6705 		panic("retval:%d tp:%p t_inpcb:NULL state:%d",
6706 		    retval, tp, prev_state);
6707 	}
6708 #endif
6709 	if (retval == 0) {
6710 		/*
6711 		 * If retval is 1 the tcb is unlocked and most likely the tp
6712 		 * is gone.
6713 		 */
6714 		INP_WLOCK_ASSERT(tp->t_inpcb);
6715 		tcp_rack_xmit_timer_commit(rack, tp);
6716 		if (((tp->snd_max - tp->snd_una) > tp->snd_wnd) &&
6717 		    (rack->rc_in_persist == 0)){
6718 			/*
6719 			 * The peer shrunk its window on us to the point
6720 			 * where we have sent too much. The only thing
6721 			 * we can do here is stop any timers and
6722 			 * enter persist. We most likely lost the last
6723 			 * bytes we sent but oh well, we will have to
6724 			 * retransmit them after the peer is caught up.
6725 			 */
6726 			if (rack->rc_inp->inp_in_hpts)
6727 				tcp_hpts_remove(rack->rc_inp, HPTS_REMOVE_OUTPUT);
6728 			rack_timer_cancel(tp, rack, cts, __LINE__);
6729 			rack_enter_persist(tp, rack, cts);
6730 			rack_start_hpts_timer(rack, tp, tcp_ts_getticks(), __LINE__, 0, 0, 0);
6731 			way_out = 3;
6732 			goto done_with_input;
6733 		}
6734 		if (nxt_pkt == 0) {
6735 			if (rack->r_wanted_output != 0) {
6736 				did_out = 1;
6737 				(void)tp->t_fb->tfb_tcp_output(tp);
6738 			}
6739 			rack_start_hpts_timer(rack, tp, cts, __LINE__, 0, 0, 0);
6740 		}
6741 		if (((rack->r_ctl.rc_hpts_flags & PACE_TMR_MASK) == 0) &&
6742 		    (SEQ_GT(tp->snd_max, tp->snd_una) ||
6743 		     (tp->t_flags & TF_DELACK) ||
6744 		     ((tcp_always_keepalive || rack->rc_inp->inp_socket->so_options & SO_KEEPALIVE) &&
6745 		      (tp->t_state <= TCPS_CLOSING)))) {
6746 			/* We could not send (probably in the hpts but stopped the timer earlier)? */
6747 			if ((tp->snd_max == tp->snd_una) &&
6748 			    ((tp->t_flags & TF_DELACK) == 0) &&
6749 			    (rack->r_ctl.rc_hpts_flags & PACE_PKT_OUTPUT)) {
6750 				/* keep alive not needed if we are hptsi output yet */
6751 				;
6752 			} else {
6753 				if (rack->rc_inp->inp_in_hpts)
6754 					tcp_hpts_remove(rack->rc_inp, HPTS_REMOVE_OUTPUT);
6755 				rack_start_hpts_timer(rack, tp, tcp_ts_getticks(), __LINE__, 0, 0, 0);
6756 			}
6757 			way_out = 1;
6758 		} else {
6759 			/* Do we have the correct timer running? */
6760 			rack_timer_audit(tp, rack, &so->so_snd);
6761 			way_out = 2;
6762 		}
6763 	done_with_input:
6764 		rack_log_doseg_done(rack, cts, nxt_pkt, did_out, way_out);
6765 		if (did_out)
6766 			rack->r_wanted_output = 0;
6767 #ifdef INVARIANTS
6768 		if (tp->t_inpcb == NULL) {
6769 			panic("OP:%d retval:%d tp:%p t_inpcb:NULL state:%d",
6770 			      did_out,
6771 			      retval, tp, prev_state);
6772 		}
6773 #endif
6774 		INP_WUNLOCK(tp->t_inpcb);
6775 	}
6776 }
6777 
6778 void
6779 rack_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
6780     struct tcpcb *tp, int32_t drop_hdrlen, int32_t tlen, uint8_t iptos)
6781 {
6782 	struct timeval tv;
6783 #ifdef RSS
6784 	struct tcp_function_block *tfb;
6785 	struct tcp_rack *rack;
6786 	struct epoch_tracker et;
6787 
6788 	rack = (struct tcp_rack *)tp->t_fb_ptr;
6789 	if (rack->r_state == 0) {
6790 		/*
6791 		 * Initial input (ACK to SYN-ACK etc)lets go ahead and get
6792 		 * it processed
6793 		 */
6794 		INP_INFO_RLOCK_ET(&V_tcbinfo, et);
6795 		tcp_get_usecs(&tv);
6796 		rack_hpts_do_segment(m, th, so, tp, drop_hdrlen,
6797 		    tlen, iptos, 0, &tv);
6798 		INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
6799 		return;
6800 	}
6801 	tcp_queue_to_input(tp, m, th, tlen, drop_hdrlen, iptos);
6802 	INP_WUNLOCK(tp->t_inpcb);
6803 #else
6804 	tcp_get_usecs(&tv);
6805 	rack_hpts_do_segment(m, th, so, tp, drop_hdrlen,
6806 	    tlen, iptos, 0, &tv);
6807 #endif
6808 }
6809 
6810 struct rack_sendmap *
6811 tcp_rack_output(struct tcpcb *tp, struct tcp_rack *rack, uint32_t tsused)
6812 {
6813 	struct rack_sendmap *rsm = NULL;
6814 	int32_t idx;
6815 	uint32_t srtt_cur, srtt = 0, thresh = 0, ts_low = 0;
6816 
6817 	/* Return the next guy to be re-transmitted */
6818 	if (TAILQ_EMPTY(&rack->r_ctl.rc_map)) {
6819 		return (NULL);
6820 	}
6821 	if (tp->t_flags & TF_SENTFIN) {
6822 		/* retran the end FIN? */
6823 		return (NULL);
6824 	}
6825 	/* ok lets look at this one */
6826 	rsm = TAILQ_FIRST(&rack->r_ctl.rc_tmap);
6827 	if (rsm && ((rsm->r_flags & RACK_ACKED) == 0)) {
6828 		goto check_it;
6829 	}
6830 	rsm = rack_find_lowest_rsm(rack);
6831 	if (rsm == NULL) {
6832 		return (NULL);
6833 	}
6834 check_it:
6835 	srtt_cur = tp->t_srtt >> TCP_RTT_SHIFT;
6836 	srtt = TICKS_2_MSEC(srtt_cur);
6837 	if (rack->rc_rack_rtt && (srtt > rack->rc_rack_rtt))
6838 		srtt = rack->rc_rack_rtt;
6839 	if (rsm->r_flags & RACK_ACKED) {
6840 		return (NULL);
6841 	}
6842 	if ((rsm->r_flags & RACK_SACK_PASSED) == 0) {
6843 		/* Its not yet ready */
6844 		return (NULL);
6845 	}
6846 	idx = rsm->r_rtr_cnt - 1;
6847 	ts_low = rsm->r_tim_lastsent[idx];
6848 	thresh = rack_calc_thresh_rack(rack, srtt, tsused);
6849 	if (tsused <= ts_low) {
6850 		return (NULL);
6851 	}
6852 	if ((tsused - ts_low) >= thresh) {
6853 		return (rsm);
6854 	}
6855 	return (NULL);
6856 }
6857 
6858 static int
6859 rack_output(struct tcpcb *tp)
6860 {
6861 	struct socket *so;
6862 	uint32_t recwin, sendwin;
6863 	uint32_t sb_offset;
6864 	int32_t len, flags, error = 0;
6865 	struct mbuf *m;
6866 	struct mbuf *mb;
6867 	uint32_t if_hw_tsomaxsegcount = 0;
6868 	uint32_t if_hw_tsomaxsegsize;
6869 	long tot_len_this_send = 0;
6870 	struct ip *ip = NULL;
6871 #ifdef TCPDEBUG
6872 	struct ipovly *ipov = NULL;
6873 #endif
6874 	struct udphdr *udp = NULL;
6875 	struct tcp_rack *rack;
6876 	struct tcphdr *th;
6877 	uint8_t pass = 0;
6878 	uint8_t wanted_cookie = 0;
6879 	u_char opt[TCP_MAXOLEN];
6880 	unsigned ipoptlen, optlen, hdrlen, ulen=0;
6881 	uint32_t rack_seq;
6882 
6883 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
6884 	unsigned ipsec_optlen = 0;
6885 
6886 #endif
6887 	int32_t idle, sendalot;
6888 	int32_t sub_from_prr = 0;
6889 	volatile int32_t sack_rxmit;
6890 	struct rack_sendmap *rsm = NULL;
6891 	int32_t tso, mtu, would_have_fin = 0;
6892 	struct tcpopt to;
6893 	int32_t slot = 0;
6894 	uint32_t cts;
6895 	uint8_t hpts_calling, doing_tlp = 0;
6896 	int32_t do_a_prefetch;
6897 	int32_t prefetch_rsm = 0;
6898 	int32_t prefetch_so_done = 0;
6899 	struct tcp_log_buffer *lgb = NULL;
6900 	struct inpcb *inp;
6901 	struct sockbuf *sb;
6902 #ifdef INET6
6903 	struct ip6_hdr *ip6 = NULL;
6904 	int32_t isipv6;
6905 #endif
6906 	/* setup and take the cache hits here */
6907 	rack = (struct tcp_rack *)tp->t_fb_ptr;
6908 	inp = rack->rc_inp;
6909 	so = inp->inp_socket;
6910 	sb = &so->so_snd;
6911 	kern_prefetch(sb, &do_a_prefetch);
6912 	do_a_prefetch = 1;
6913 
6914 	INP_WLOCK_ASSERT(inp);
6915 #ifdef TCP_OFFLOAD
6916 	if (tp->t_flags & TF_TOE)
6917 		return (tcp_offload_output(tp));
6918 #endif
6919 #ifdef INET6
6920 	if (rack->r_state) {
6921 		/* Use the cache line loaded if possible */
6922 		isipv6 = rack->r_is_v6;
6923 	} else {
6924 		isipv6 = (inp->inp_vflag & INP_IPV6) != 0;
6925 	}
6926 #endif
6927 	cts = tcp_ts_getticks();
6928 	if (((rack->r_ctl.rc_hpts_flags & PACE_PKT_OUTPUT) == 0) &&
6929 	    inp->inp_in_hpts) {
6930 		/*
6931 		 * We are on the hpts for some timer but not hptsi output.
6932 		 * Remove from the hpts unconditionally.
6933 		 */
6934 		rack_timer_cancel(tp, rack, cts, __LINE__);
6935 	}
6936 	/* Mark that we have called rack_output(). */
6937 	if ((rack->r_timer_override) ||
6938 	    (tp->t_flags & TF_FORCEDATA) ||
6939 	    (tp->t_state < TCPS_ESTABLISHED)) {
6940 		if (tp->t_inpcb->inp_in_hpts)
6941 			tcp_hpts_remove(tp->t_inpcb, HPTS_REMOVE_OUTPUT);
6942 	} else if (tp->t_inpcb->inp_in_hpts) {
6943 		/*
6944 		 * On the hpts you can't pass even if ACKNOW is on, we will
6945 		 * when the hpts fires.
6946 		 */
6947 		counter_u64_add(rack_out_size[TCP_MSS_ACCT_INPACE], 1);
6948 		return (0);
6949 	}
6950 	hpts_calling = inp->inp_hpts_calls;
6951 	inp->inp_hpts_calls = 0;
6952 	if (rack->r_ctl.rc_hpts_flags & PACE_TMR_MASK) {
6953 		if (rack_process_timers(tp, rack, cts, hpts_calling)) {
6954 			counter_u64_add(rack_out_size[TCP_MSS_ACCT_ATIMER], 1);
6955 			return (0);
6956 		}
6957 	}
6958 	rack->r_wanted_output = 0;
6959 	rack->r_timer_override = 0;
6960 	/*
6961 	 * For TFO connections in SYN_SENT or SYN_RECEIVED,
6962 	 * only allow the initial SYN or SYN|ACK and those sent
6963 	 * by the retransmit timer.
6964 	 */
6965 	if (IS_FASTOPEN(tp->t_flags) &&
6966 	    ((tp->t_state == TCPS_SYN_RECEIVED) ||
6967 	     (tp->t_state == TCPS_SYN_SENT)) &&
6968 	    SEQ_GT(tp->snd_max, tp->snd_una) && /* initial SYN or SYN|ACK sent */
6969 	    (tp->t_rxtshift == 0))              /* not a retransmit */
6970 		return (0);
6971 	/*
6972 	 * Determine length of data that should be transmitted, and flags
6973 	 * that will be used. If there is some data or critical controls
6974 	 * (SYN, RST) to send, then transmit; otherwise, investigate
6975 	 * further.
6976 	 */
6977 	idle = (tp->t_flags & TF_LASTIDLE) || (tp->snd_max == tp->snd_una);
6978 #ifdef NETFLIX_CWV
6979 	if (tp->cwv_enabled) {
6980 		if ((tp->cwv_cwnd_valid == 0) &&
6981 		    TCPS_HAVEESTABLISHED(tp->t_state) &&
6982 		    (tp->snd_cwnd > tp->snd_cwv.init_cwnd))
6983 			tcp_newcwv_nvp_closedown(tp);
6984 	} else
6985 #endif
6986 	if (tp->t_idle_reduce) {
6987 		if (idle && ((ticks - tp->t_rcvtime) >= tp->t_rxtcur))
6988 			rack_cc_after_idle(tp,
6989 		            (rack->r_idle_reduce_largest ? 1 :0));
6990 	}
6991 	tp->t_flags &= ~TF_LASTIDLE;
6992 	if (idle) {
6993 		if (tp->t_flags & TF_MORETOCOME) {
6994 			tp->t_flags |= TF_LASTIDLE;
6995 			idle = 0;
6996 		}
6997 	}
6998 again:
6999 	/*
7000 	 * If we've recently taken a timeout, snd_max will be greater than
7001 	 * snd_nxt.  There may be SACK information that allows us to avoid
7002 	 * resending already delivered data.  Adjust snd_nxt accordingly.
7003 	 */
7004 	sendalot = 0;
7005 	cts = tcp_ts_getticks();
7006 	tso = 0;
7007 	mtu = 0;
7008 	sb_offset = tp->snd_max - tp->snd_una;
7009 	sendwin = min(tp->snd_wnd, tp->snd_cwnd);
7010 
7011 	flags = tcp_outflags[tp->t_state];
7012 	/*
7013 	 * Send any SACK-generated retransmissions.  If we're explicitly
7014 	 * trying to send out new data (when sendalot is 1), bypass this
7015 	 * function. If we retransmit in fast recovery mode, decrement
7016 	 * snd_cwnd, since we're replacing a (future) new transmission with
7017 	 * a retransmission now, and we previously incremented snd_cwnd in
7018 	 * tcp_input().
7019 	 */
7020 	/*
7021 	 * Still in sack recovery , reset rxmit flag to zero.
7022 	 */
7023 	while (rack->rc_free_cnt < rack_free_cache) {
7024 		rsm = rack_alloc(rack);
7025 		if (rsm == NULL) {
7026 			if (inp->inp_hpts_calls)
7027 				/* Retry in a ms */
7028 				slot = 1;
7029 			goto just_return_nolock;
7030 		}
7031 		TAILQ_INSERT_TAIL(&rack->r_ctl.rc_free, rsm, r_next);
7032 		rack->rc_free_cnt++;
7033 		rsm = NULL;
7034 	}
7035 	if (inp->inp_hpts_calls)
7036 		inp->inp_hpts_calls = 0;
7037 	sack_rxmit = 0;
7038 	len = 0;
7039 	rsm = NULL;
7040 	if (flags & TH_RST) {
7041 		SOCKBUF_LOCK(sb);
7042 		goto send;
7043 	}
7044 	if (rack->r_ctl.rc_tlpsend) {
7045 		/* Tail loss probe */
7046 		long cwin;
7047 		long tlen;
7048 
7049 		doing_tlp = 1;
7050 		rsm = rack->r_ctl.rc_tlpsend;
7051 		rack->r_ctl.rc_tlpsend = NULL;
7052 		sack_rxmit = 1;
7053 		tlen = rsm->r_end - rsm->r_start;
7054 		if (tlen > tp->t_maxseg)
7055 			tlen = tp->t_maxseg;
7056 		KASSERT(SEQ_LEQ(tp->snd_una, rsm->r_start),
7057 		    ("%s:%d: r.start:%u < SND.UNA:%u; tp:%p, rack:%p, rsm:%p",
7058 		    __func__, __LINE__,
7059 		    rsm->r_start, tp->snd_una, tp, rack, rsm));
7060 		sb_offset = rsm->r_start - tp->snd_una;
7061 		cwin = min(tp->snd_wnd, tlen);
7062 		len = cwin;
7063 	} else if (rack->r_ctl.rc_resend) {
7064 		/* Retransmit timer */
7065 		rsm = rack->r_ctl.rc_resend;
7066 		rack->r_ctl.rc_resend = NULL;
7067 		len = rsm->r_end - rsm->r_start;
7068 		sack_rxmit = 1;
7069 		sendalot = 0;
7070 		KASSERT(SEQ_LEQ(tp->snd_una, rsm->r_start),
7071 		    ("%s:%d: r.start:%u < SND.UNA:%u; tp:%p, rack:%p, rsm:%p",
7072 		    __func__, __LINE__,
7073 		    rsm->r_start, tp->snd_una, tp, rack, rsm));
7074 		sb_offset = rsm->r_start - tp->snd_una;
7075 		if (len >= tp->t_maxseg) {
7076 			len = tp->t_maxseg;
7077 		}
7078 	} else if ((rack->rc_in_persist == 0) &&
7079 	    ((rsm = tcp_rack_output(tp, rack, cts)) != NULL)) {
7080 		long tlen;
7081 
7082 		if ((!IN_RECOVERY(tp->t_flags)) &&
7083 		    ((tp->t_flags & (TF_WASFRECOVERY | TF_WASCRECOVERY)) == 0)) {
7084 			/* Enter recovery if not induced by a time-out */
7085 			rack->r_ctl.rc_rsm_start = rsm->r_start;
7086 			rack->r_ctl.rc_cwnd_at = tp->snd_cwnd;
7087 			rack->r_ctl.rc_ssthresh_at = tp->snd_ssthresh;
7088 			rack_cong_signal(tp, NULL, CC_NDUPACK);
7089 			/*
7090 			 * When we enter recovery we need to assure we send
7091 			 * one packet.
7092 			 */
7093 			rack->r_ctl.rc_prr_sndcnt = tp->t_maxseg;
7094 		}
7095 #ifdef INVARIANTS
7096 		if (SEQ_LT(rsm->r_start, tp->snd_una)) {
7097 			panic("Huh, tp:%p rack:%p rsm:%p start:%u < snd_una:%u\n",
7098 			    tp, rack, rsm, rsm->r_start, tp->snd_una);
7099 		}
7100 #endif
7101 		tlen = rsm->r_end - rsm->r_start;
7102 		KASSERT(SEQ_LEQ(tp->snd_una, rsm->r_start),
7103 		    ("%s:%d: r.start:%u < SND.UNA:%u; tp:%p, rack:%p, rsm:%p",
7104 		    __func__, __LINE__,
7105 		    rsm->r_start, tp->snd_una, tp, rack, rsm));
7106 		sb_offset = rsm->r_start - tp->snd_una;
7107 		if (tlen > rack->r_ctl.rc_prr_sndcnt) {
7108 			len = rack->r_ctl.rc_prr_sndcnt;
7109 		} else {
7110 			len = tlen;
7111 		}
7112 		if (len >= tp->t_maxseg) {
7113 			sendalot = 1;
7114 			len = tp->t_maxseg;
7115 		} else {
7116 			sendalot = 0;
7117 			if ((rack->rc_timer_up == 0) &&
7118 			    (len < tlen)) {
7119 				/*
7120 				 * If its not a timer don't send a partial
7121 				 * segment.
7122 				 */
7123 				len = 0;
7124 				goto just_return_nolock;
7125 			}
7126 		}
7127 		if (len > 0) {
7128 			sub_from_prr = 1;
7129 			sack_rxmit = 1;
7130 			TCPSTAT_INC(tcps_sack_rexmits);
7131 			TCPSTAT_ADD(tcps_sack_rexmit_bytes,
7132 			    min(len, tp->t_maxseg));
7133 			counter_u64_add(rack_rtm_prr_retran, 1);
7134 		}
7135 	}
7136 	if (rsm && (rsm->r_flags & RACK_HAS_FIN)) {
7137 		/* we are retransmitting the fin */
7138 		len--;
7139 		if (len) {
7140 			/*
7141 			 * When retransmitting data do *not* include the
7142 			 * FIN. This could happen from a TLP probe.
7143 			 */
7144 			flags &= ~TH_FIN;
7145 		}
7146 	}
7147 #ifdef INVARIANTS
7148 	/* For debugging */
7149 	rack->r_ctl.rc_rsm_at_retran = rsm;
7150 #endif
7151 	/*
7152 	 * Get standard flags, and add SYN or FIN if requested by 'hidden'
7153 	 * state flags.
7154 	 */
7155 	if (tp->t_flags & TF_NEEDFIN)
7156 		flags |= TH_FIN;
7157 	if (tp->t_flags & TF_NEEDSYN)
7158 		flags |= TH_SYN;
7159 	if ((sack_rxmit == 0) && (prefetch_rsm == 0)) {
7160 		void *end_rsm;
7161 		end_rsm = TAILQ_LAST_FAST(&rack->r_ctl.rc_tmap, rack_sendmap, r_tnext);
7162 		if (end_rsm)
7163 			kern_prefetch(end_rsm, &prefetch_rsm);
7164 		prefetch_rsm = 1;
7165 	}
7166 	SOCKBUF_LOCK(sb);
7167 	/*
7168 	 * If in persist timeout with window of 0, send 1 byte. Otherwise,
7169 	 * if window is small but nonzero and time TF_SENTFIN expired, we
7170 	 * will send what we can and go to transmit state.
7171 	 */
7172 	if (tp->t_flags & TF_FORCEDATA) {
7173 		if (sendwin == 0) {
7174 			/*
7175 			 * If we still have some data to send, then clear
7176 			 * the FIN bit.  Usually this would happen below
7177 			 * when it realizes that we aren't sending all the
7178 			 * data.  However, if we have exactly 1 byte of
7179 			 * unsent data, then it won't clear the FIN bit
7180 			 * below, and if we are in persist state, we wind up
7181 			 * sending the packet without recording that we sent
7182 			 * the FIN bit.
7183 			 *
7184 			 * We can't just blindly clear the FIN bit, because
7185 			 * if we don't have any more data to send then the
7186 			 * probe will be the FIN itself.
7187 			 */
7188 			if (sb_offset < sbused(sb))
7189 				flags &= ~TH_FIN;
7190 			sendwin = 1;
7191 		} else {
7192 			if (rack->rc_in_persist)
7193 				rack_exit_persist(tp, rack);
7194 			/*
7195 			 * If we are dropping persist mode then we need to
7196 			 * correct snd_nxt/snd_max and off.
7197 			 */
7198 			tp->snd_nxt = tp->snd_max;
7199 			sb_offset = tp->snd_nxt - tp->snd_una;
7200 		}
7201 	}
7202 	/*
7203 	 * If snd_nxt == snd_max and we have transmitted a FIN, the
7204 	 * sb_offset will be > 0 even if so_snd.sb_cc is 0, resulting in a
7205 	 * negative length.  This can also occur when TCP opens up its
7206 	 * congestion window while receiving additional duplicate acks after
7207 	 * fast-retransmit because TCP will reset snd_nxt to snd_max after
7208 	 * the fast-retransmit.
7209 	 *
7210 	 * In the normal retransmit-FIN-only case, however, snd_nxt will be
7211 	 * set to snd_una, the sb_offset will be 0, and the length may wind
7212 	 * up 0.
7213 	 *
7214 	 * If sack_rxmit is true we are retransmitting from the scoreboard
7215 	 * in which case len is already set.
7216 	 */
7217 	if (sack_rxmit == 0) {
7218 		uint32_t avail;
7219 
7220 		avail = sbavail(sb);
7221 		if (SEQ_GT(tp->snd_nxt, tp->snd_una) && avail)
7222 			sb_offset = tp->snd_nxt - tp->snd_una;
7223 		else
7224 			sb_offset = 0;
7225 		if (IN_RECOVERY(tp->t_flags) == 0) {
7226 			if (rack->r_ctl.rc_tlp_new_data) {
7227 				/* TLP is forcing out new data */
7228 				if (rack->r_ctl.rc_tlp_new_data > (uint32_t) (avail - sb_offset)) {
7229 					rack->r_ctl.rc_tlp_new_data = (uint32_t) (avail - sb_offset);
7230 				}
7231 				if (rack->r_ctl.rc_tlp_new_data > tp->snd_wnd)
7232 					len = tp->snd_wnd;
7233 				else
7234 					len = rack->r_ctl.rc_tlp_new_data;
7235 				rack->r_ctl.rc_tlp_new_data = 0;
7236 				doing_tlp = 1;
7237 			} else {
7238 				if (sendwin > avail) {
7239 					/* use the available */
7240 					if (avail > sb_offset) {
7241 						len = (int32_t)(avail - sb_offset);
7242 					} else {
7243 						len = 0;
7244 					}
7245 				} else {
7246 					if (sendwin > sb_offset) {
7247 						len = (int32_t)(sendwin - sb_offset);
7248 					} else {
7249 						len = 0;
7250 					}
7251 				}
7252 			}
7253 		} else {
7254 			uint32_t outstanding;
7255 
7256 			/*
7257 			 * We are inside of a SACK recovery episode and are
7258 			 * sending new data, having retransmitted all the
7259 			 * data possible so far in the scoreboard.
7260 			 */
7261 			outstanding = tp->snd_max - tp->snd_una;
7262 			if ((rack->r_ctl.rc_prr_sndcnt + outstanding) > tp->snd_wnd)
7263 				len = 0;
7264 			else if (avail > sb_offset)
7265 				len = avail - sb_offset;
7266 			else
7267 				len = 0;
7268 			if (len > 0) {
7269 				if (len > rack->r_ctl.rc_prr_sndcnt)
7270 					len = rack->r_ctl.rc_prr_sndcnt;
7271 
7272 				if (len > 0) {
7273 					sub_from_prr = 1;
7274 					counter_u64_add(rack_rtm_prr_newdata, 1);
7275 				}
7276 			}
7277 			if (len > tp->t_maxseg) {
7278 				/*
7279 				 * We should never send more than a MSS when
7280 				 * retransmitting or sending new data in prr
7281 				 * mode unless the override flag is on. Most
7282 				 * likely the PRR algorithm is not going to
7283 				 * let us send a lot as well :-)
7284 				 */
7285 				if (rack->r_ctl.rc_prr_sendalot == 0)
7286 					len = tp->t_maxseg;
7287 			} else if (len < tp->t_maxseg) {
7288 				/*
7289 				 * Do we send any? The idea here is if the
7290 				 * send empty's the socket buffer we want to
7291 				 * do it. However if not then lets just wait
7292 				 * for our prr_sndcnt to get bigger.
7293 				 */
7294 				long leftinsb;
7295 
7296 				leftinsb = sbavail(sb) - sb_offset;
7297 				if (leftinsb > len) {
7298 					/* This send does not empty the sb */
7299 					len = 0;
7300 				}
7301 			}
7302 		}
7303 	}
7304 	if (prefetch_so_done == 0) {
7305 		kern_prefetch(so, &prefetch_so_done);
7306 		prefetch_so_done = 1;
7307 	}
7308 	/*
7309 	 * Lop off SYN bit if it has already been sent.  However, if this is
7310 	 * SYN-SENT state and if segment contains data and if we don't know
7311 	 * that foreign host supports TAO, suppress sending segment.
7312 	 */
7313 	if ((flags & TH_SYN) && SEQ_GT(tp->snd_nxt, tp->snd_una) &&
7314 	    ((sack_rxmit == 0) && (tp->t_rxtshift == 0))) {
7315 		if (tp->t_state != TCPS_SYN_RECEIVED)
7316 			flags &= ~TH_SYN;
7317 		/*
7318 		 * When sending additional segments following a TFO SYN|ACK,
7319 		 * do not include the SYN bit.
7320 		 */
7321 		if (IS_FASTOPEN(tp->t_flags) &&
7322 		    (tp->t_state == TCPS_SYN_RECEIVED))
7323 			flags &= ~TH_SYN;
7324 		sb_offset--, len++;
7325 	}
7326 	/*
7327 	 * Be careful not to send data and/or FIN on SYN segments. This
7328 	 * measure is needed to prevent interoperability problems with not
7329 	 * fully conformant TCP implementations.
7330 	 */
7331 	if ((flags & TH_SYN) && (tp->t_flags & TF_NOOPT)) {
7332 		len = 0;
7333 		flags &= ~TH_FIN;
7334 	}
7335 	/*
7336 	 * On TFO sockets, ensure no data is sent in the following cases:
7337 	 *
7338 	 *  - When retransmitting SYN|ACK on a passively-created socket
7339 	 *
7340 	 *  - When retransmitting SYN on an actively created socket
7341 	 *
7342 	 *  - When sending a zero-length cookie (cookie request) on an
7343 	 *    actively created socket
7344 	 *
7345 	 *  - When the socket is in the CLOSED state (RST is being sent)
7346 	 */
7347 	if (IS_FASTOPEN(tp->t_flags) &&
7348 	    (((flags & TH_SYN) && (tp->t_rxtshift > 0)) ||
7349 	     ((tp->t_state == TCPS_SYN_SENT) &&
7350 	      (tp->t_tfo_client_cookie_len == 0)) ||
7351 	     (flags & TH_RST))) {
7352 		sack_rxmit = 0;
7353 		len = 0;
7354 	}
7355 	/* Without fast-open there should never be data sent on a SYN */
7356 	if ((flags & TH_SYN) && (!IS_FASTOPEN(tp->t_flags)))
7357 		len = 0;
7358 	if (len <= 0) {
7359 		/*
7360 		 * If FIN has been sent but not acked, but we haven't been
7361 		 * called to retransmit, len will be < 0.  Otherwise, window
7362 		 * shrank after we sent into it.  If window shrank to 0,
7363 		 * cancel pending retransmit, pull snd_nxt back to (closed)
7364 		 * window, and set the persist timer if it isn't already
7365 		 * going.  If the window didn't close completely, just wait
7366 		 * for an ACK.
7367 		 *
7368 		 * We also do a general check here to ensure that we will
7369 		 * set the persist timer when we have data to send, but a
7370 		 * 0-byte window. This makes sure the persist timer is set
7371 		 * even if the packet hits one of the "goto send" lines
7372 		 * below.
7373 		 */
7374 		len = 0;
7375 		if ((tp->snd_wnd == 0) &&
7376 		    (TCPS_HAVEESTABLISHED(tp->t_state)) &&
7377 		    (sb_offset < (int)sbavail(sb))) {
7378 			tp->snd_nxt = tp->snd_una;
7379 			rack_enter_persist(tp, rack, cts);
7380 		}
7381 	}
7382 	/* len will be >= 0 after this point. */
7383 	KASSERT(len >= 0, ("[%s:%d]: len < 0", __func__, __LINE__));
7384 	tcp_sndbuf_autoscale(tp, so, sendwin);
7385 	/*
7386 	 * Decide if we can use TCP Segmentation Offloading (if supported by
7387 	 * hardware).
7388 	 *
7389 	 * TSO may only be used if we are in a pure bulk sending state.  The
7390 	 * presence of TCP-MD5, SACK retransmits, SACK advertizements and IP
7391 	 * options prevent using TSO.  With TSO the TCP header is the same
7392 	 * (except for the sequence number) for all generated packets.  This
7393 	 * makes it impossible to transmit any options which vary per
7394 	 * generated segment or packet.
7395 	 *
7396 	 * IPv4 handling has a clear separation of ip options and ip header
7397 	 * flags while IPv6 combines both in in6p_outputopts. ip6_optlen() does
7398 	 * the right thing below to provide length of just ip options and thus
7399 	 * checking for ipoptlen is enough to decide if ip options are present.
7400 	 */
7401 
7402 #ifdef INET6
7403 	if (isipv6)
7404 		ipoptlen = ip6_optlen(tp->t_inpcb);
7405 	else
7406 #endif
7407 		if (tp->t_inpcb->inp_options)
7408 			ipoptlen = tp->t_inpcb->inp_options->m_len -
7409 			    offsetof(struct ipoption, ipopt_list);
7410 		else
7411 			ipoptlen = 0;
7412 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
7413 	/*
7414 	 * Pre-calculate here as we save another lookup into the darknesses
7415 	 * of IPsec that way and can actually decide if TSO is ok.
7416 	 */
7417 #ifdef INET6
7418 	if (isipv6 && IPSEC_ENABLED(ipv6))
7419 		ipsec_optlen = IPSEC_HDRSIZE(ipv6, tp->t_inpcb);
7420 #ifdef INET
7421 	else
7422 #endif
7423 #endif				/* INET6 */
7424 #ifdef INET
7425 	if (IPSEC_ENABLED(ipv4))
7426 		ipsec_optlen = IPSEC_HDRSIZE(ipv4, tp->t_inpcb);
7427 #endif				/* INET */
7428 #endif
7429 
7430 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
7431 	ipoptlen += ipsec_optlen;
7432 #endif
7433 	if ((tp->t_flags & TF_TSO) && V_tcp_do_tso && len > tp->t_maxseg &&
7434 	    (tp->t_port == 0) &&
7435 	    ((tp->t_flags & TF_SIGNATURE) == 0) &&
7436 	    tp->rcv_numsacks == 0 && sack_rxmit == 0 &&
7437 	    ipoptlen == 0)
7438 		tso = 1;
7439 	{
7440 		uint32_t outstanding;
7441 
7442 		outstanding = tp->snd_max - tp->snd_una;
7443 		if (tp->t_flags & TF_SENTFIN) {
7444 			/*
7445 			 * If we sent a fin, snd_max is 1 higher than
7446 			 * snd_una
7447 			 */
7448 			outstanding--;
7449 		}
7450 		if (outstanding > 0) {
7451 			/*
7452 			 * This is sub-optimal. We only send a stand alone
7453 			 * FIN on its own segment.
7454 			 */
7455 			if (flags & TH_FIN) {
7456 				flags &= ~TH_FIN;
7457 				would_have_fin = 1;
7458 			}
7459 		} else if (sack_rxmit) {
7460 			if ((rsm->r_flags & RACK_HAS_FIN) == 0)
7461 				flags &= ~TH_FIN;
7462 		} else {
7463 			if (SEQ_LT(tp->snd_nxt + len, tp->snd_una +
7464 			    sbused(sb)))
7465 				flags &= ~TH_FIN;
7466 		}
7467 	}
7468 	recwin = sbspace(&so->so_rcv);
7469 
7470 	/*
7471 	 * Sender silly window avoidance.   We transmit under the following
7472 	 * conditions when len is non-zero:
7473 	 *
7474 	 * - We have a full segment (or more with TSO) - This is the last
7475 	 * buffer in a write()/send() and we are either idle or running
7476 	 * NODELAY - we've timed out (e.g. persist timer) - we have more
7477 	 * then 1/2 the maximum send window's worth of data (receiver may be
7478 	 * limited the window size) - we need to retransmit
7479 	 */
7480 	if (len) {
7481 		if (len >= tp->t_maxseg) {
7482 			pass = 1;
7483 			goto send;
7484 		}
7485 		/*
7486 		 * NOTE! on localhost connections an 'ack' from the remote
7487 		 * end may occur synchronously with the output and cause us
7488 		 * to flush a buffer queued with moretocome.  XXX
7489 		 *
7490 		 */
7491 		if (!(tp->t_flags & TF_MORETOCOME) &&	/* normal case */
7492 		    (idle || (tp->t_flags & TF_NODELAY)) &&
7493 		    ((uint32_t)len + (uint32_t)sb_offset >= sbavail(&so->so_snd)) &&
7494 		    (tp->t_flags & TF_NOPUSH) == 0) {
7495 			pass = 2;
7496 			goto send;
7497 		}
7498 		if (tp->t_flags & TF_FORCEDATA) {	/* typ. timeout case */
7499 			pass = 3;
7500 			goto send;
7501 		}
7502 		if ((tp->snd_una == tp->snd_max) && len) {	/* Nothing outstanding */
7503 			goto send;
7504 		}
7505 		if (len >= tp->max_sndwnd / 2 && tp->max_sndwnd > 0) {
7506 			pass = 4;
7507 			goto send;
7508 		}
7509 		if (SEQ_LT(tp->snd_nxt, tp->snd_max)) {	/* retransmit case */
7510 			pass = 5;
7511 			goto send;
7512 		}
7513 		if (sack_rxmit) {
7514 			pass = 6;
7515 			goto send;
7516 		}
7517 	}
7518 	/*
7519 	 * Sending of standalone window updates.
7520 	 *
7521 	 * Window updates are important when we close our window due to a
7522 	 * full socket buffer and are opening it again after the application
7523 	 * reads data from it.  Once the window has opened again and the
7524 	 * remote end starts to send again the ACK clock takes over and
7525 	 * provides the most current window information.
7526 	 *
7527 	 * We must avoid the silly window syndrome whereas every read from
7528 	 * the receive buffer, no matter how small, causes a window update
7529 	 * to be sent.  We also should avoid sending a flurry of window
7530 	 * updates when the socket buffer had queued a lot of data and the
7531 	 * application is doing small reads.
7532 	 *
7533 	 * Prevent a flurry of pointless window updates by only sending an
7534 	 * update when we can increase the advertized window by more than
7535 	 * 1/4th of the socket buffer capacity.  When the buffer is getting
7536 	 * full or is very small be more aggressive and send an update
7537 	 * whenever we can increase by two mss sized segments. In all other
7538 	 * situations the ACK's to new incoming data will carry further
7539 	 * window increases.
7540 	 *
7541 	 * Don't send an independent window update if a delayed ACK is
7542 	 * pending (it will get piggy-backed on it) or the remote side
7543 	 * already has done a half-close and won't send more data.  Skip
7544 	 * this if the connection is in T/TCP half-open state.
7545 	 */
7546 	if (recwin > 0 && !(tp->t_flags & TF_NEEDSYN) &&
7547 	    !(tp->t_flags & TF_DELACK) &&
7548 	    !TCPS_HAVERCVDFIN(tp->t_state)) {
7549 		/*
7550 		 * "adv" is the amount we could increase the window, taking
7551 		 * into account that we are limited by TCP_MAXWIN <<
7552 		 * tp->rcv_scale.
7553 		 */
7554 		int32_t adv;
7555 		int oldwin;
7556 
7557 		adv = min(recwin, (long)TCP_MAXWIN << tp->rcv_scale);
7558 		if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt)) {
7559 			oldwin = (tp->rcv_adv - tp->rcv_nxt);
7560 			adv -= oldwin;
7561 		} else
7562 			oldwin = 0;
7563 
7564 		/*
7565 		 * If the new window size ends up being the same as the old
7566 		 * size when it is scaled, then don't force a window update.
7567 		 */
7568 		if (oldwin >> tp->rcv_scale == (adv + oldwin) >> tp->rcv_scale)
7569 			goto dontupdate;
7570 
7571 		if (adv >= (int32_t)(2 * tp->t_maxseg) &&
7572 		    (adv >= (int32_t)(so->so_rcv.sb_hiwat / 4) ||
7573 		    recwin <= (int32_t)(so->so_rcv.sb_hiwat / 8) ||
7574 		    so->so_rcv.sb_hiwat <= 8 * tp->t_maxseg)) {
7575 			pass = 7;
7576 			goto send;
7577 		}
7578 		if (2 * adv >= (int32_t) so->so_rcv.sb_hiwat)
7579 			goto send;
7580 	}
7581 dontupdate:
7582 
7583 	/*
7584 	 * Send if we owe the peer an ACK, RST, SYN, or urgent data.  ACKNOW
7585 	 * is also a catch-all for the retransmit timer timeout case.
7586 	 */
7587 	if (tp->t_flags & TF_ACKNOW) {
7588 		pass = 8;
7589 		goto send;
7590 	}
7591 	if (((flags & TH_SYN) && (tp->t_flags & TF_NEEDSYN) == 0)) {
7592 		pass = 9;
7593 		goto send;
7594 	}
7595 	if (SEQ_GT(tp->snd_up, tp->snd_una)) {
7596 		pass = 10;
7597 		goto send;
7598 	}
7599 	/*
7600 	 * If our state indicates that FIN should be sent and we have not
7601 	 * yet done so, then we need to send.
7602 	 */
7603 	if ((flags & TH_FIN) &&
7604 	    (tp->snd_nxt == tp->snd_una)) {
7605 		pass = 11;
7606 		goto send;
7607 	}
7608 	/*
7609 	 * No reason to send a segment, just return.
7610 	 */
7611 just_return:
7612 	SOCKBUF_UNLOCK(sb);
7613 just_return_nolock:
7614 	if (tot_len_this_send == 0)
7615 		counter_u64_add(rack_out_size[TCP_MSS_ACCT_JUSTRET], 1);
7616 	rack_start_hpts_timer(rack, tp, cts, __LINE__, slot, tot_len_this_send, 1);
7617 	rack_log_type_just_return(rack, cts, tot_len_this_send, slot, hpts_calling);
7618 	tp->t_flags &= ~TF_FORCEDATA;
7619 	return (0);
7620 
7621 send:
7622 	if (doing_tlp == 0) {
7623 		/*
7624 		 * Data not a TLP, and its not the rxt firing. If it is the
7625 		 * rxt firing, we want to leave the tlp_in_progress flag on
7626 		 * so we don't send another TLP. It has to be a rack timer
7627 		 * or normal send (response to acked data) to clear the tlp
7628 		 * in progress flag.
7629 		 */
7630 		rack->rc_tlp_in_progress = 0;
7631 	}
7632 	SOCKBUF_LOCK_ASSERT(sb);
7633 	if (len > 0) {
7634 		if (len >= tp->t_maxseg)
7635 			tp->t_flags2 |= TF2_PLPMTU_MAXSEGSNT;
7636 		else
7637 			tp->t_flags2 &= ~TF2_PLPMTU_MAXSEGSNT;
7638 	}
7639 	/*
7640 	 * Before ESTABLISHED, force sending of initial options unless TCP
7641 	 * set not to do any options. NOTE: we assume that the IP/TCP header
7642 	 * plus TCP options always fit in a single mbuf, leaving room for a
7643 	 * maximum link header, i.e. max_linkhdr + sizeof (struct tcpiphdr)
7644 	 * + optlen <= MCLBYTES
7645 	 */
7646 	optlen = 0;
7647 #ifdef INET6
7648 	if (isipv6)
7649 		hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
7650 	else
7651 #endif
7652 		hdrlen = sizeof(struct tcpiphdr);
7653 
7654 	/*
7655 	 * Compute options for segment. We only have to care about SYN and
7656 	 * established connection segments.  Options for SYN-ACK segments
7657 	 * are handled in TCP syncache.
7658 	 */
7659 	to.to_flags = 0;
7660 	if ((tp->t_flags & TF_NOOPT) == 0) {
7661 		/* Maximum segment size. */
7662 		if (flags & TH_SYN) {
7663 			tp->snd_nxt = tp->iss;
7664 			to.to_mss = tcp_mssopt(&inp->inp_inc);
7665 #ifdef NETFLIX_TCPOUDP
7666 			if (tp->t_port)
7667 				to.to_mss -= V_tcp_udp_tunneling_overhead;
7668 #endif
7669 			to.to_flags |= TOF_MSS;
7670 
7671 			/*
7672 			 * On SYN or SYN|ACK transmits on TFO connections,
7673 			 * only include the TFO option if it is not a
7674 			 * retransmit, as the presence of the TFO option may
7675 			 * have caused the original SYN or SYN|ACK to have
7676 			 * been dropped by a middlebox.
7677 			 */
7678 			if (IS_FASTOPEN(tp->t_flags) &&
7679 			    (tp->t_rxtshift == 0)) {
7680 				if (tp->t_state == TCPS_SYN_RECEIVED) {
7681 					to.to_tfo_len = TCP_FASTOPEN_COOKIE_LEN;
7682 					to.to_tfo_cookie =
7683 					    (u_int8_t *)&tp->t_tfo_cookie.server;
7684 					to.to_flags |= TOF_FASTOPEN;
7685 					wanted_cookie = 1;
7686 				} else if (tp->t_state == TCPS_SYN_SENT) {
7687 					to.to_tfo_len =
7688 					    tp->t_tfo_client_cookie_len;
7689 					to.to_tfo_cookie =
7690 					    tp->t_tfo_cookie.client;
7691 					to.to_flags |= TOF_FASTOPEN;
7692 					wanted_cookie = 1;
7693 					/*
7694 					 * If we wind up having more data to
7695 					 * send with the SYN than can fit in
7696 					 * one segment, don't send any more
7697 					 * until the SYN|ACK comes back from
7698 					 * the other end.
7699 					 */
7700 					sendalot = 0;
7701 				}
7702 			}
7703 		}
7704 		/* Window scaling. */
7705 		if ((flags & TH_SYN) && (tp->t_flags & TF_REQ_SCALE)) {
7706 			to.to_wscale = tp->request_r_scale;
7707 			to.to_flags |= TOF_SCALE;
7708 		}
7709 		/* Timestamps. */
7710 		if ((tp->t_flags & TF_RCVD_TSTMP) ||
7711 		    ((flags & TH_SYN) && (tp->t_flags & TF_REQ_TSTMP))) {
7712 			to.to_tsval = cts + tp->ts_offset;
7713 			to.to_tsecr = tp->ts_recent;
7714 			to.to_flags |= TOF_TS;
7715 		}
7716 		/* Set receive buffer autosizing timestamp. */
7717 		if (tp->rfbuf_ts == 0 &&
7718 		    (so->so_rcv.sb_flags & SB_AUTOSIZE))
7719 			tp->rfbuf_ts = tcp_ts_getticks();
7720 		/* Selective ACK's. */
7721 		if (flags & TH_SYN)
7722 			to.to_flags |= TOF_SACKPERM;
7723 		else if (TCPS_HAVEESTABLISHED(tp->t_state) &&
7724 		    tp->rcv_numsacks > 0) {
7725 			to.to_flags |= TOF_SACK;
7726 			to.to_nsacks = tp->rcv_numsacks;
7727 			to.to_sacks = (u_char *)tp->sackblks;
7728 		}
7729 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE)
7730 		/* TCP-MD5 (RFC2385). */
7731 		if (tp->t_flags & TF_SIGNATURE)
7732 			to.to_flags |= TOF_SIGNATURE;
7733 #endif				/* TCP_SIGNATURE */
7734 
7735 		/* Processing the options. */
7736 		hdrlen += optlen = tcp_addoptions(&to, opt);
7737 		/*
7738 		 * If we wanted a TFO option to be added, but it was unable
7739 		 * to fit, ensure no data is sent.
7740 		 */
7741 		if (IS_FASTOPEN(tp->t_flags) && wanted_cookie &&
7742 		    !(to.to_flags & TOF_FASTOPEN))
7743 			len = 0;
7744 	}
7745 #ifdef NETFLIX_TCPOUDP
7746 	if (tp->t_port) {
7747 		if (V_tcp_udp_tunneling_port == 0) {
7748 			/* The port was removed?? */
7749 			SOCKBUF_UNLOCK(&so->so_snd);
7750 			return (EHOSTUNREACH);
7751 		}
7752 		hdrlen += sizeof(struct udphdr);
7753 	}
7754 #endif
7755 	ipoptlen = 0;
7756 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
7757 	ipoptlen += ipsec_optlen;
7758 #endif
7759 
7760 	/*
7761 	 * Adjust data length if insertion of options will bump the packet
7762 	 * length beyond the t_maxseg length. Clear the FIN bit because we
7763 	 * cut off the tail of the segment.
7764 	 */
7765 	if (len + optlen + ipoptlen > tp->t_maxseg) {
7766 		if (flags & TH_FIN) {
7767 			would_have_fin = 1;
7768 			flags &= ~TH_FIN;
7769 		}
7770 		if (tso) {
7771 			uint32_t if_hw_tsomax;
7772 			uint32_t moff;
7773 			int32_t max_len;
7774 
7775 			/* extract TSO information */
7776 			if_hw_tsomax = tp->t_tsomax;
7777 			if_hw_tsomaxsegcount = tp->t_tsomaxsegcount;
7778 			if_hw_tsomaxsegsize = tp->t_tsomaxsegsize;
7779 			KASSERT(ipoptlen == 0,
7780 			    ("%s: TSO can't do IP options", __func__));
7781 
7782 			/*
7783 			 * Check if we should limit by maximum payload
7784 			 * length:
7785 			 */
7786 			if (if_hw_tsomax != 0) {
7787 				/* compute maximum TSO length */
7788 				max_len = (if_hw_tsomax - hdrlen -
7789 				    max_linkhdr);
7790 				if (max_len <= 0) {
7791 					len = 0;
7792 				} else if (len > max_len) {
7793 					sendalot = 1;
7794 					len = max_len;
7795 				}
7796 			}
7797 			/*
7798 			 * Prevent the last segment from being fractional
7799 			 * unless the send sockbuf can be emptied:
7800 			 */
7801 			max_len = (tp->t_maxseg - optlen);
7802 			if ((sb_offset + len) < sbavail(sb)) {
7803 				moff = len % (u_int)max_len;
7804 				if (moff != 0) {
7805 					len -= moff;
7806 					sendalot = 1;
7807 				}
7808 			}
7809 			/*
7810 			 * In case there are too many small fragments don't
7811 			 * use TSO:
7812 			 */
7813 			if (len <= max_len) {
7814 				len = max_len;
7815 				sendalot = 1;
7816 				tso = 0;
7817 			}
7818 			/*
7819 			 * Send the FIN in a separate segment after the bulk
7820 			 * sending is done. We don't trust the TSO
7821 			 * implementations to clear the FIN flag on all but
7822 			 * the last segment.
7823 			 */
7824 			if (tp->t_flags & TF_NEEDFIN)
7825 				sendalot = 1;
7826 
7827 		} else {
7828 			len = tp->t_maxseg - optlen - ipoptlen;
7829 			sendalot = 1;
7830 		}
7831 	} else
7832 		tso = 0;
7833 	KASSERT(len + hdrlen + ipoptlen <= IP_MAXPACKET,
7834 	    ("%s: len > IP_MAXPACKET", __func__));
7835 #ifdef DIAGNOSTIC
7836 #ifdef INET6
7837 	if (max_linkhdr + hdrlen > MCLBYTES)
7838 #else
7839 	if (max_linkhdr + hdrlen > MHLEN)
7840 #endif
7841 		panic("tcphdr too big");
7842 #endif
7843 
7844 	/*
7845 	 * This KASSERT is here to catch edge cases at a well defined place.
7846 	 * Before, those had triggered (random) panic conditions further
7847 	 * down.
7848 	 */
7849 	KASSERT(len >= 0, ("[%s:%d]: len < 0", __func__, __LINE__));
7850 	if ((len == 0) &&
7851 	    (flags & TH_FIN) &&
7852 	    (sbused(sb))) {
7853 		/*
7854 		 * We have outstanding data, don't send a fin by itself!.
7855 		 */
7856 		goto just_return;
7857 	}
7858 	/*
7859 	 * Grab a header mbuf, attaching a copy of data to be transmitted,
7860 	 * and initialize the header from the template for sends on this
7861 	 * connection.
7862 	 */
7863 	if (len) {
7864 		uint32_t max_val;
7865 		uint32_t moff;
7866 
7867 		if (rack->rc_pace_max_segs)
7868 			max_val = rack->rc_pace_max_segs * tp->t_maxseg;
7869 		else
7870 			max_val = len;
7871 		/*
7872 		 * We allow a limit on sending with hptsi.
7873 		 */
7874 		if (len > max_val) {
7875 			len = max_val;
7876 		}
7877 #ifdef INET6
7878 		if (MHLEN < hdrlen + max_linkhdr)
7879 			m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
7880 		else
7881 #endif
7882 			m = m_gethdr(M_NOWAIT, MT_DATA);
7883 
7884 		if (m == NULL) {
7885 			SOCKBUF_UNLOCK(sb);
7886 			error = ENOBUFS;
7887 			sack_rxmit = 0;
7888 			goto out;
7889 		}
7890 		m->m_data += max_linkhdr;
7891 		m->m_len = hdrlen;
7892 
7893 		/*
7894 		 * Start the m_copy functions from the closest mbuf to the
7895 		 * sb_offset in the socket buffer chain.
7896 		 */
7897 		mb = sbsndptr_noadv(sb, sb_offset, &moff);
7898 		if (len <= MHLEN - hdrlen - max_linkhdr) {
7899 			m_copydata(mb, moff, (int)len,
7900 			    mtod(m, caddr_t)+hdrlen);
7901 			if (SEQ_LT(tp->snd_nxt, tp->snd_max))
7902 				sbsndptr_adv(sb, mb, len);
7903 			m->m_len += len;
7904 		} else {
7905 			struct sockbuf *msb;
7906 
7907 			if (SEQ_LT(tp->snd_nxt, tp->snd_max))
7908 				msb = NULL;
7909 			else
7910 				msb = sb;
7911 			m->m_next = tcp_m_copym(mb, moff, &len,
7912 			    if_hw_tsomaxsegcount, if_hw_tsomaxsegsize, msb);
7913 			if (len <= (tp->t_maxseg - optlen)) {
7914 				/*
7915 				 * Must have ran out of mbufs for the copy
7916 				 * shorten it to no longer need tso. Lets
7917 				 * not put on sendalot since we are low on
7918 				 * mbufs.
7919 				 */
7920 				tso = 0;
7921 			}
7922 			if (m->m_next == NULL) {
7923 				SOCKBUF_UNLOCK(sb);
7924 				(void)m_free(m);
7925 				error = ENOBUFS;
7926 				sack_rxmit = 0;
7927 				goto out;
7928 			}
7929 		}
7930 		if ((tp->t_flags & TF_FORCEDATA) && len == 1) {
7931 			TCPSTAT_INC(tcps_sndprobe);
7932 #ifdef NETFLIX_STATS
7933 			if (SEQ_LT(tp->snd_nxt, tp->snd_max))
7934 				stats_voi_update_abs_u32(tp->t_stats,
7935 				    VOI_TCP_RETXPB, len);
7936 			else
7937 				stats_voi_update_abs_u64(tp->t_stats,
7938 				    VOI_TCP_TXPB, len);
7939 #endif
7940 		} else if (SEQ_LT(tp->snd_nxt, tp->snd_max) || sack_rxmit) {
7941 			if (rsm && (rsm->r_flags & RACK_TLP)) {
7942 				/*
7943 				 * TLP should not count in retran count, but
7944 				 * in its own bin
7945 				 */
7946 				counter_u64_add(rack_tlp_retran, 1);
7947 				counter_u64_add(rack_tlp_retran_bytes, len);
7948 			} else {
7949 				tp->t_sndrexmitpack++;
7950 				TCPSTAT_INC(tcps_sndrexmitpack);
7951 				TCPSTAT_ADD(tcps_sndrexmitbyte, len);
7952 			}
7953 #ifdef NETFLIX_STATS
7954 			stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_RETXPB,
7955 			    len);
7956 #endif
7957 		} else {
7958 			TCPSTAT_INC(tcps_sndpack);
7959 			TCPSTAT_ADD(tcps_sndbyte, len);
7960 #ifdef NETFLIX_STATS
7961 			stats_voi_update_abs_u64(tp->t_stats, VOI_TCP_TXPB,
7962 			    len);
7963 #endif
7964 		}
7965 		/*
7966 		 * If we're sending everything we've got, set PUSH. (This
7967 		 * will keep happy those implementations which only give
7968 		 * data to the user when a buffer fills or a PUSH comes in.)
7969 		 */
7970 		if (sb_offset + len == sbused(sb) &&
7971 		    sbused(sb) &&
7972 		    !(flags & TH_SYN))
7973 			flags |= TH_PUSH;
7974 
7975 		/*
7976 		 * Are we doing hptsi, if so we must calculate the slot. We
7977 		 * only do hptsi in ESTABLISHED and with no RESET being
7978 		 * sent where we have data to send.
7979 		 */
7980 		if (((tp->t_state == TCPS_ESTABLISHED) ||
7981 		    (tp->t_state == TCPS_CLOSE_WAIT) ||
7982 		    ((tp->t_state == TCPS_FIN_WAIT_1) &&
7983 		    ((tp->t_flags & TF_SENTFIN) == 0) &&
7984 		    ((flags & TH_FIN) == 0))) &&
7985 		    ((flags & TH_RST) == 0) &&
7986 		    (rack->rc_always_pace)) {
7987 			/*
7988 			 * We use the most optimistic possible cwnd/srtt for
7989 			 * sending calculations. This will make our
7990 			 * calculation anticipate getting more through
7991 			 * quicker then possible. But thats ok we don't want
7992 			 * the peer to have a gap in data sending.
7993 			 */
7994 			uint32_t srtt, cwnd, tr_perms = 0;
7995 
7996 			if (rack->r_ctl.rc_rack_min_rtt)
7997 				srtt = rack->r_ctl.rc_rack_min_rtt;
7998 			else
7999 				srtt = TICKS_2_MSEC((tp->t_srtt >> TCP_RTT_SHIFT));
8000 			if (rack->r_ctl.rc_rack_largest_cwnd)
8001 				cwnd = rack->r_ctl.rc_rack_largest_cwnd;
8002 			else
8003 				cwnd = tp->snd_cwnd;
8004 			tr_perms = cwnd / srtt;
8005 			if (tr_perms == 0) {
8006 				tr_perms = tp->t_maxseg;
8007 			}
8008 			tot_len_this_send += len;
8009 			/*
8010 			 * Calculate how long this will take to drain, if
8011 			 * the calculation comes out to zero, thats ok we
8012 			 * will use send_a_lot to possibly spin around for
8013 			 * more increasing tot_len_this_send to the point
8014 			 * that its going to require a pace, or we hit the
8015 			 * cwnd. Which in that case we are just waiting for
8016 			 * a ACK.
8017 			 */
8018 			slot = tot_len_this_send / tr_perms;
8019 			/* Now do we reduce the time so we don't run dry? */
8020 			if (slot && rack->rc_pace_reduce) {
8021 				int32_t reduce;
8022 
8023 				reduce = (slot / rack->rc_pace_reduce);
8024 				if (reduce < slot) {
8025 					slot -= reduce;
8026 				} else
8027 					slot = 0;
8028 			}
8029 			if (rack->r_enforce_min_pace &&
8030 			    (slot == 0) &&
8031 			    (tot_len_this_send >= (rack->r_min_pace_seg_thresh * tp->t_maxseg))) {
8032 				/* We are enforcing a minimum pace time of 1ms */
8033 				slot = rack->r_enforce_min_pace;
8034 			}
8035 		}
8036 		SOCKBUF_UNLOCK(sb);
8037 	} else {
8038 		SOCKBUF_UNLOCK(sb);
8039 		if (tp->t_flags & TF_ACKNOW)
8040 			TCPSTAT_INC(tcps_sndacks);
8041 		else if (flags & (TH_SYN | TH_FIN | TH_RST))
8042 			TCPSTAT_INC(tcps_sndctrl);
8043 		else if (SEQ_GT(tp->snd_up, tp->snd_una))
8044 			TCPSTAT_INC(tcps_sndurg);
8045 		else
8046 			TCPSTAT_INC(tcps_sndwinup);
8047 
8048 		m = m_gethdr(M_NOWAIT, MT_DATA);
8049 		if (m == NULL) {
8050 			error = ENOBUFS;
8051 			sack_rxmit = 0;
8052 			goto out;
8053 		}
8054 #ifdef INET6
8055 		if (isipv6 && (MHLEN < hdrlen + max_linkhdr) &&
8056 		    MHLEN >= hdrlen) {
8057 			M_ALIGN(m, hdrlen);
8058 		} else
8059 #endif
8060 			m->m_data += max_linkhdr;
8061 		m->m_len = hdrlen;
8062 	}
8063 	SOCKBUF_UNLOCK_ASSERT(sb);
8064 	m->m_pkthdr.rcvif = (struct ifnet *)0;
8065 #ifdef MAC
8066 	mac_inpcb_create_mbuf(inp, m);
8067 #endif
8068 #ifdef INET6
8069 	if (isipv6) {
8070 		ip6 = mtod(m, struct ip6_hdr *);
8071 #ifdef NETFLIX_TCPOUDP
8072 		if (tp->t_port) {
8073 			udp = (struct udphdr *)((caddr_t)ip6 + ipoptlen + sizeof(struct ip6_hdr));
8074 			udp->uh_sport = htons(V_tcp_udp_tunneling_port);
8075 			udp->uh_dport = tp->t_port;
8076 			ulen = hdrlen + len - sizeof(struct ip6_hdr);
8077 			udp->uh_ulen = htons(ulen);
8078 			th = (struct tcphdr *)(udp + 1);
8079 		} else
8080 #endif
8081 			th = (struct tcphdr *)(ip6 + 1);
8082 		tcpip_fillheaders(inp, ip6, th);
8083 	} else
8084 #endif				/* INET6 */
8085 	{
8086 		ip = mtod(m, struct ip *);
8087 #ifdef TCPDEBUG
8088 		ipov = (struct ipovly *)ip;
8089 #endif
8090 #ifdef NETFLIX_TCPOUDP
8091 		if (tp->t_port) {
8092 			udp = (struct udphdr *)((caddr_t)ip + ipoptlen + sizeof(struct ip));
8093 			udp->uh_sport = htons(V_tcp_udp_tunneling_port);
8094 			udp->uh_dport = tp->t_port;
8095 			ulen = hdrlen + len - sizeof(struct ip);
8096 			udp->uh_ulen = htons(ulen);
8097 			th = (struct tcphdr *)(udp + 1);
8098 		} else
8099 #endif
8100 			th = (struct tcphdr *)(ip + 1);
8101 		tcpip_fillheaders(inp, ip, th);
8102 	}
8103 	/*
8104 	 * Fill in fields, remembering maximum advertised window for use in
8105 	 * delaying messages about window sizes. If resending a FIN, be sure
8106 	 * not to use a new sequence number.
8107 	 */
8108 	if (flags & TH_FIN && tp->t_flags & TF_SENTFIN &&
8109 	    tp->snd_nxt == tp->snd_max)
8110 		tp->snd_nxt--;
8111 	/*
8112 	 * If we are starting a connection, send ECN setup SYN packet. If we
8113 	 * are on a retransmit, we may resend those bits a number of times
8114 	 * as per RFC 3168.
8115 	 */
8116 	if (tp->t_state == TCPS_SYN_SENT && V_tcp_do_ecn == 1) {
8117 		if (tp->t_rxtshift >= 1) {
8118 			if (tp->t_rxtshift <= V_tcp_ecn_maxretries)
8119 				flags |= TH_ECE | TH_CWR;
8120 		} else
8121 			flags |= TH_ECE | TH_CWR;
8122 	}
8123 	if (tp->t_state == TCPS_ESTABLISHED &&
8124 	    (tp->t_flags & TF_ECN_PERMIT)) {
8125 		/*
8126 		 * If the peer has ECN, mark data packets with ECN capable
8127 		 * transmission (ECT). Ignore pure ack packets,
8128 		 * retransmissions and window probes.
8129 		 */
8130 		if (len > 0 && SEQ_GEQ(tp->snd_nxt, tp->snd_max) &&
8131 		    !((tp->t_flags & TF_FORCEDATA) && len == 1)) {
8132 #ifdef INET6
8133 			if (isipv6)
8134 				ip6->ip6_flow |= htonl(IPTOS_ECN_ECT0 << 20);
8135 			else
8136 #endif
8137 				ip->ip_tos |= IPTOS_ECN_ECT0;
8138 			TCPSTAT_INC(tcps_ecn_ect0);
8139 		}
8140 		/*
8141 		 * Reply with proper ECN notifications.
8142 		 */
8143 		if (tp->t_flags & TF_ECN_SND_CWR) {
8144 			flags |= TH_CWR;
8145 			tp->t_flags &= ~TF_ECN_SND_CWR;
8146 		}
8147 		if (tp->t_flags & TF_ECN_SND_ECE)
8148 			flags |= TH_ECE;
8149 	}
8150 	/*
8151 	 * If we are doing retransmissions, then snd_nxt will not reflect
8152 	 * the first unsent octet.  For ACK only packets, we do not want the
8153 	 * sequence number of the retransmitted packet, we want the sequence
8154 	 * number of the next unsent octet.  So, if there is no data (and no
8155 	 * SYN or FIN), use snd_max instead of snd_nxt when filling in
8156 	 * ti_seq.  But if we are in persist state, snd_max might reflect
8157 	 * one byte beyond the right edge of the window, so use snd_nxt in
8158 	 * that case, since we know we aren't doing a retransmission.
8159 	 * (retransmit and persist are mutually exclusive...)
8160 	 */
8161 	if (sack_rxmit == 0) {
8162 		if (len || (flags & (TH_SYN | TH_FIN)) ||
8163 		    rack->rc_in_persist) {
8164 			th->th_seq = htonl(tp->snd_nxt);
8165 			rack_seq = tp->snd_nxt;
8166 		} else if (flags & TH_RST) {
8167 			/*
8168 			 * For a Reset send the last cum ack in sequence
8169 			 * (this like any other choice may still generate a
8170 			 * challenge ack, if a ack-update packet is in
8171 			 * flight).
8172 			 */
8173 			th->th_seq = htonl(tp->snd_una);
8174 			rack_seq = tp->snd_una;
8175 		} else {
8176 			th->th_seq = htonl(tp->snd_max);
8177 			rack_seq = tp->snd_max;
8178 		}
8179 	} else {
8180 		th->th_seq = htonl(rsm->r_start);
8181 		rack_seq = rsm->r_start;
8182 	}
8183 	th->th_ack = htonl(tp->rcv_nxt);
8184 	if (optlen) {
8185 		bcopy(opt, th + 1, optlen);
8186 		th->th_off = (sizeof(struct tcphdr) + optlen) >> 2;
8187 	}
8188 	th->th_flags = flags;
8189 	/*
8190 	 * Calculate receive window.  Don't shrink window, but avoid silly
8191 	 * window syndrome.
8192 	 * If a RST segment is sent, advertise a window of zero.
8193 	 */
8194 	if (flags & TH_RST) {
8195 		recwin = 0;
8196 	} else {
8197 		if (recwin < (long)(so->so_rcv.sb_hiwat / 4) &&
8198 		    recwin < (long)tp->t_maxseg)
8199 			recwin = 0;
8200 		if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt) &&
8201 		    recwin < (long)(tp->rcv_adv - tp->rcv_nxt))
8202 			recwin = (long)(tp->rcv_adv - tp->rcv_nxt);
8203 		if (recwin > (long)TCP_MAXWIN << tp->rcv_scale)
8204 			recwin = (long)TCP_MAXWIN << tp->rcv_scale;
8205 	}
8206 
8207 	/*
8208 	 * According to RFC1323 the window field in a SYN (i.e., a <SYN> or
8209 	 * <SYN,ACK>) segment itself is never scaled.  The <SYN,ACK> case is
8210 	 * handled in syncache.
8211 	 */
8212 	if (flags & TH_SYN)
8213 		th->th_win = htons((u_short)
8214 		    (min(sbspace(&so->so_rcv), TCP_MAXWIN)));
8215 	else
8216 		th->th_win = htons((u_short)(recwin >> tp->rcv_scale));
8217 	/*
8218 	 * Adjust the RXWIN0SENT flag - indicate that we have advertised a 0
8219 	 * window.  This may cause the remote transmitter to stall.  This
8220 	 * flag tells soreceive() to disable delayed acknowledgements when
8221 	 * draining the buffer.  This can occur if the receiver is
8222 	 * attempting to read more data than can be buffered prior to
8223 	 * transmitting on the connection.
8224 	 */
8225 	if (th->th_win == 0) {
8226 		tp->t_sndzerowin++;
8227 		tp->t_flags |= TF_RXWIN0SENT;
8228 	} else
8229 		tp->t_flags &= ~TF_RXWIN0SENT;
8230 	if (SEQ_GT(tp->snd_up, tp->snd_nxt)) {
8231 		th->th_urp = htons((u_short)(tp->snd_up - tp->snd_nxt));
8232 		th->th_flags |= TH_URG;
8233 	} else
8234 		/*
8235 		 * If no urgent pointer to send, then we pull the urgent
8236 		 * pointer to the left edge of the send window so that it
8237 		 * doesn't drift into the send window on sequence number
8238 		 * wraparound.
8239 		 */
8240 		tp->snd_up = tp->snd_una;	/* drag it along */
8241 
8242 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE)
8243 	if (to.to_flags & TOF_SIGNATURE) {
8244 		/*
8245 		 * Calculate MD5 signature and put it into the place
8246 		 * determined before.
8247 		 * NOTE: since TCP options buffer doesn't point into
8248 		 * mbuf's data, calculate offset and use it.
8249 		 */
8250 		if (!TCPMD5_ENABLED() || TCPMD5_OUTPUT(m, th,
8251 		    (u_char *)(th + 1) + (to.to_signature - opt)) != 0) {
8252 			/*
8253 			 * Do not send segment if the calculation of MD5
8254 			 * digest has failed.
8255 			 */
8256 			goto out;
8257 		}
8258 	}
8259 #endif
8260 
8261 	/*
8262 	 * Put TCP length in extended header, and then checksum extended
8263 	 * header and data.
8264 	 */
8265 	m->m_pkthdr.len = hdrlen + len;	/* in6_cksum() need this */
8266 #ifdef INET6
8267 	if (isipv6) {
8268 		/*
8269 		 * ip6_plen is not need to be filled now, and will be filled
8270 		 * in ip6_output.
8271 		 */
8272 		if (tp->t_port) {
8273 			m->m_pkthdr.csum_flags = CSUM_UDP_IPV6;
8274 			m->m_pkthdr.csum_data = offsetof(struct udphdr, uh_sum);
8275 			udp->uh_sum = in6_cksum_pseudo(ip6, ulen, IPPROTO_UDP, 0);
8276 			th->th_sum = htons(0);
8277 		} else {
8278 			m->m_pkthdr.csum_flags = CSUM_TCP_IPV6;
8279 			m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
8280 			th->th_sum = in6_cksum_pseudo(ip6,
8281 			    sizeof(struct tcphdr) + optlen + len, IPPROTO_TCP,
8282 			    0);
8283 		}
8284 	}
8285 #endif
8286 #if defined(INET6) && defined(INET)
8287 	else
8288 #endif
8289 #ifdef INET
8290 	{
8291 		if (tp->t_port) {
8292 			m->m_pkthdr.csum_flags = CSUM_UDP;
8293 			m->m_pkthdr.csum_data = offsetof(struct udphdr, uh_sum);
8294 			udp->uh_sum = in_pseudo(ip->ip_src.s_addr,
8295 			   ip->ip_dst.s_addr, htons(ulen + IPPROTO_UDP));
8296 			th->th_sum = htons(0);
8297 		} else {
8298 			m->m_pkthdr.csum_flags = CSUM_TCP;
8299 			m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
8300 			th->th_sum = in_pseudo(ip->ip_src.s_addr,
8301 			    ip->ip_dst.s_addr, htons(sizeof(struct tcphdr) +
8302 			    IPPROTO_TCP + len + optlen));
8303 		}
8304 		/* IP version must be set here for ipv4/ipv6 checking later */
8305 		KASSERT(ip->ip_v == IPVERSION,
8306 		    ("%s: IP version incorrect: %d", __func__, ip->ip_v));
8307 	}
8308 #endif
8309 
8310 	/*
8311 	 * Enable TSO and specify the size of the segments. The TCP pseudo
8312 	 * header checksum is always provided. XXX: Fixme: This is currently
8313 	 * not the case for IPv6.
8314 	 */
8315 	if (tso) {
8316 		KASSERT(len > tp->t_maxseg - optlen,
8317 		    ("%s: len <= tso_segsz", __func__));
8318 		m->m_pkthdr.csum_flags |= CSUM_TSO;
8319 		m->m_pkthdr.tso_segsz = tp->t_maxseg - optlen;
8320 	}
8321 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
8322 	KASSERT(len + hdrlen + ipoptlen - ipsec_optlen == m_length(m, NULL),
8323 	    ("%s: mbuf chain shorter than expected: %d + %u + %u - %u != %u",
8324 	    __func__, len, hdrlen, ipoptlen, ipsec_optlen, m_length(m, NULL)));
8325 #else
8326 	KASSERT(len + hdrlen + ipoptlen == m_length(m, NULL),
8327 	    ("%s: mbuf chain shorter than expected: %d + %u + %u != %u",
8328 	    __func__, len, hdrlen, ipoptlen, m_length(m, NULL)));
8329 #endif
8330 
8331 #ifdef TCP_HHOOK
8332 	/* Run HHOOK_TCP_ESTABLISHED_OUT helper hooks. */
8333 	hhook_run_tcp_est_out(tp, th, &to, len, tso);
8334 #endif
8335 
8336 #ifdef TCPDEBUG
8337 	/*
8338 	 * Trace.
8339 	 */
8340 	if (so->so_options & SO_DEBUG) {
8341 		u_short save = 0;
8342 
8343 #ifdef INET6
8344 		if (!isipv6)
8345 #endif
8346 		{
8347 			save = ipov->ih_len;
8348 			ipov->ih_len = htons(m->m_pkthdr.len	/* - hdrlen +
8349 			      * (th->th_off << 2) */ );
8350 		}
8351 		tcp_trace(TA_OUTPUT, tp->t_state, tp, mtod(m, void *), th, 0);
8352 #ifdef INET6
8353 		if (!isipv6)
8354 #endif
8355 			ipov->ih_len = save;
8356 	}
8357 #endif				/* TCPDEBUG */
8358 
8359 	/* We're getting ready to send; log now. */
8360 	if (tp->t_logstate != TCP_LOG_STATE_OFF) {
8361 		union tcp_log_stackspecific log;
8362 
8363 		memset(&log.u_bbr, 0, sizeof(log.u_bbr));
8364 		log.u_bbr.inhpts = rack->rc_inp->inp_in_hpts;
8365 		log.u_bbr.ininput = rack->rc_inp->inp_in_input;
8366 		log.u_bbr.flex1 = rack->r_ctl.rc_prr_sndcnt;
8367 		if (rsm || sack_rxmit) {
8368 			log.u_bbr.flex8 = 1;
8369 		} else {
8370 			log.u_bbr.flex8 = 0;
8371 		}
8372 		lgb = tcp_log_event_(tp, th, &so->so_rcv, &so->so_snd, TCP_LOG_OUT, ERRNO_UNK,
8373 		    len, &log, false, NULL, NULL, 0, NULL);
8374 	} else
8375 		lgb = NULL;
8376 
8377 	/*
8378 	 * Fill in IP length and desired time to live and send to IP level.
8379 	 * There should be a better way to handle ttl and tos; we could keep
8380 	 * them in the template, but need a way to checksum without them.
8381 	 */
8382 	/*
8383 	 * m->m_pkthdr.len should have been set before cksum calcuration,
8384 	 * because in6_cksum() need it.
8385 	 */
8386 #ifdef INET6
8387 	if (isipv6) {
8388 		/*
8389 		 * we separately set hoplimit for every segment, since the
8390 		 * user might want to change the value via setsockopt. Also,
8391 		 * desired default hop limit might be changed via Neighbor
8392 		 * Discovery.
8393 		 */
8394 		ip6->ip6_hlim = in6_selecthlim(inp, NULL);
8395 
8396 		/*
8397 		 * Set the packet size here for the benefit of DTrace
8398 		 * probes. ip6_output() will set it properly; it's supposed
8399 		 * to include the option header lengths as well.
8400 		 */
8401 		ip6->ip6_plen = htons(m->m_pkthdr.len - sizeof(*ip6));
8402 
8403 		if (V_path_mtu_discovery && tp->t_maxseg > V_tcp_minmss)
8404 			tp->t_flags2 |= TF2_PLPMTU_PMTUD;
8405 		else
8406 			tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
8407 
8408 		if (tp->t_state == TCPS_SYN_SENT)
8409 			TCP_PROBE5(connect__request, NULL, tp, ip6, tp, th);
8410 
8411 		TCP_PROBE5(send, NULL, tp, ip6, tp, th);
8412 		/* TODO: IPv6 IP6TOS_ECT bit on */
8413 		error = ip6_output(m, tp->t_inpcb->in6p_outputopts,
8414 		    &inp->inp_route6,
8415 		    ((so->so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0),
8416 		    NULL, NULL, inp);
8417 
8418 		if (error == EMSGSIZE && inp->inp_route6.ro_rt != NULL)
8419 			mtu = inp->inp_route6.ro_rt->rt_mtu;
8420 	}
8421 #endif				/* INET6 */
8422 #if defined(INET) && defined(INET6)
8423 	else
8424 #endif
8425 #ifdef INET
8426 	{
8427 		ip->ip_len = htons(m->m_pkthdr.len);
8428 #ifdef INET6
8429 		if (inp->inp_vflag & INP_IPV6PROTO)
8430 			ip->ip_ttl = in6_selecthlim(inp, NULL);
8431 #endif				/* INET6 */
8432 		/*
8433 		 * If we do path MTU discovery, then we set DF on every
8434 		 * packet. This might not be the best thing to do according
8435 		 * to RFC3390 Section 2. However the tcp hostcache migitates
8436 		 * the problem so it affects only the first tcp connection
8437 		 * with a host.
8438 		 *
8439 		 * NB: Don't set DF on small MTU/MSS to have a safe
8440 		 * fallback.
8441 		 */
8442 		if (V_path_mtu_discovery && tp->t_maxseg > V_tcp_minmss) {
8443 			tp->t_flags2 |= TF2_PLPMTU_PMTUD;
8444 			if (tp->t_port == 0 || len < V_tcp_minmss) {
8445 				ip->ip_off |= htons(IP_DF);
8446 			}
8447 		} else {
8448 			tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
8449 		}
8450 
8451 		if (tp->t_state == TCPS_SYN_SENT)
8452 			TCP_PROBE5(connect__request, NULL, tp, ip, tp, th);
8453 
8454 		TCP_PROBE5(send, NULL, tp, ip, tp, th);
8455 
8456 		error = ip_output(m, tp->t_inpcb->inp_options, &inp->inp_route,
8457 		    ((so->so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 0,
8458 		    inp);
8459 		if (error == EMSGSIZE && inp->inp_route.ro_rt != NULL)
8460 			mtu = inp->inp_route.ro_rt->rt_mtu;
8461 	}
8462 #endif				/* INET */
8463 
8464 out:
8465 	if (lgb) {
8466 		lgb->tlb_errno = error;
8467 		lgb = NULL;
8468 	}
8469 	/*
8470 	 * In transmit state, time the transmission and arrange for the
8471 	 * retransmit.  In persist state, just set snd_max.
8472 	 */
8473 	if (error == 0) {
8474 		if (len == 0)
8475 			counter_u64_add(rack_out_size[TCP_MSS_ACCT_SNDACK], 1);
8476 		else if (len == 1) {
8477 			counter_u64_add(rack_out_size[TCP_MSS_ACCT_PERSIST], 1);
8478 		} else if (len > 1) {
8479 			int idx;
8480 
8481 			idx = (len / tp->t_maxseg) + 3;
8482 			if (idx >= TCP_MSS_ACCT_ATIMER)
8483 				counter_u64_add(rack_out_size[(TCP_MSS_ACCT_ATIMER-1)], 1);
8484 			else
8485 				counter_u64_add(rack_out_size[idx], 1);
8486 		}
8487 	}
8488 	if (sub_from_prr && (error == 0)) {
8489 		rack->r_ctl.rc_prr_sndcnt -= len;
8490 	}
8491 	sub_from_prr = 0;
8492 	rack_log_output(tp, &to, len, rack_seq, (uint8_t) flags, error, cts,
8493 	    pass, rsm);
8494 	if ((tp->t_flags & TF_FORCEDATA) == 0 ||
8495 	    (rack->rc_in_persist == 0)) {
8496 		tcp_seq startseq = tp->snd_nxt;
8497 
8498 		/*
8499 		 * Advance snd_nxt over sequence space of this segment.
8500 		 */
8501 		if (error)
8502 			/* We don't log or do anything with errors */
8503 			goto timer;
8504 
8505 		if (flags & (TH_SYN | TH_FIN)) {
8506 			if (flags & TH_SYN)
8507 				tp->snd_nxt++;
8508 			if (flags & TH_FIN) {
8509 				tp->snd_nxt++;
8510 				tp->t_flags |= TF_SENTFIN;
8511 			}
8512 		}
8513 		/* In the ENOBUFS case we do *not* update snd_max */
8514 		if (sack_rxmit)
8515 			goto timer;
8516 
8517 		tp->snd_nxt += len;
8518 		if (SEQ_GT(tp->snd_nxt, tp->snd_max)) {
8519 			if (tp->snd_una == tp->snd_max) {
8520 				/*
8521 				 * Update the time we just added data since
8522 				 * none was outstanding.
8523 				 */
8524 				rack_log_progress_event(rack, tp, ticks, PROGRESS_START, __LINE__);
8525 				tp->t_acktime = ticks;
8526 			}
8527 			tp->snd_max = tp->snd_nxt;
8528 			/*
8529 			 * Time this transmission if not a retransmission and
8530 			 * not currently timing anything.
8531 			 * This is only relevant in case of switching back to
8532 			 * the base stack.
8533 			 */
8534 			if (tp->t_rtttime == 0) {
8535 				tp->t_rtttime = ticks;
8536 				tp->t_rtseq = startseq;
8537 				TCPSTAT_INC(tcps_segstimed);
8538 			}
8539 #ifdef NETFLIX_STATS
8540 			if (!(tp->t_flags & TF_GPUTINPROG) && len) {
8541 				tp->t_flags |= TF_GPUTINPROG;
8542 				tp->gput_seq = startseq;
8543 				tp->gput_ack = startseq +
8544 				    ulmin(sbavail(sb) - sb_offset, sendwin);
8545 				tp->gput_ts = tcp_ts_getticks();
8546 			}
8547 #endif
8548 		}
8549 		/*
8550 		 * Set retransmit timer if not currently set, and not doing
8551 		 * a pure ack or a keep-alive probe. Initial value for
8552 		 * retransmit timer is smoothed round-trip time + 2 *
8553 		 * round-trip time variance. Initialize shift counter which
8554 		 * is used for backoff of retransmit time.
8555 		 */
8556 timer:
8557 		if ((tp->snd_wnd == 0) &&
8558 		    TCPS_HAVEESTABLISHED(tp->t_state)) {
8559 			/*
8560 			 * If the persists timer was set above (right before
8561 			 * the goto send), and still needs to be on. Lets
8562 			 * make sure all is canceled. If the persist timer
8563 			 * is not running, we want to get it up.
8564 			 */
8565 			if (rack->rc_in_persist == 0) {
8566 				rack_enter_persist(tp, rack, cts);
8567 			}
8568 		}
8569 	} else {
8570 		/*
8571 		 * Persist case, update snd_max but since we are in persist
8572 		 * mode (no window) we do not update snd_nxt.
8573 		 */
8574 		int32_t xlen = len;
8575 
8576 		if (error)
8577 			goto nomore;
8578 
8579 		if (flags & TH_SYN)
8580 			++xlen;
8581 		if (flags & TH_FIN) {
8582 			++xlen;
8583 			tp->t_flags |= TF_SENTFIN;
8584 		}
8585 		/* In the ENOBUFS case we do *not* update snd_max */
8586 		if (SEQ_GT(tp->snd_nxt + xlen, tp->snd_max)) {
8587 			if (tp->snd_una == tp->snd_max) {
8588 				/*
8589 				 * Update the time we just added data since
8590 				 * none was outstanding.
8591 				 */
8592 				rack_log_progress_event(rack, tp, ticks, PROGRESS_START, __LINE__);
8593 				tp->t_acktime = ticks;
8594 			}
8595 			tp->snd_max = tp->snd_nxt + len;
8596 		}
8597 	}
8598 nomore:
8599 	if (error) {
8600 		SOCKBUF_UNLOCK_ASSERT(sb);	/* Check gotos. */
8601 		/*
8602 		 * Failures do not advance the seq counter above. For the
8603 		 * case of ENOBUFS we will fall out and retry in 1ms with
8604 		 * the hpts. Everything else will just have to retransmit
8605 		 * with the timer.
8606 		 *
8607 		 * In any case, we do not want to loop around for another
8608 		 * send without a good reason.
8609 		 */
8610 		sendalot = 0;
8611 		switch (error) {
8612 		case EPERM:
8613 			tp->t_flags &= ~TF_FORCEDATA;
8614 			tp->t_softerror = error;
8615 			return (error);
8616 		case ENOBUFS:
8617 			if (slot == 0) {
8618 				/*
8619 				 * Pace us right away to retry in a some
8620 				 * time
8621 				 */
8622 				slot = 1 + rack->rc_enobuf;
8623 				if (rack->rc_enobuf < 255)
8624 					rack->rc_enobuf++;
8625 				if (slot > (rack->rc_rack_rtt / 2)) {
8626 					slot = rack->rc_rack_rtt / 2;
8627 				}
8628 				if (slot < 10)
8629 					slot = 10;
8630 			}
8631 			counter_u64_add(rack_saw_enobuf, 1);
8632 			error = 0;
8633 			goto enobufs;
8634 		case EMSGSIZE:
8635 			/*
8636 			 * For some reason the interface we used initially
8637 			 * to send segments changed to another or lowered
8638 			 * its MTU. If TSO was active we either got an
8639 			 * interface without TSO capabilits or TSO was
8640 			 * turned off. If we obtained mtu from ip_output()
8641 			 * then update it and try again.
8642 			 */
8643 			if (tso)
8644 				tp->t_flags &= ~TF_TSO;
8645 			if (mtu != 0) {
8646 				tcp_mss_update(tp, -1, mtu, NULL, NULL);
8647 				goto again;
8648 			}
8649 			slot = 10;
8650 			rack_start_hpts_timer(rack, tp, cts, __LINE__, slot, 0, 1);
8651 			tp->t_flags &= ~TF_FORCEDATA;
8652 			return (error);
8653 		case ENETUNREACH:
8654 			counter_u64_add(rack_saw_enetunreach, 1);
8655 		case EHOSTDOWN:
8656 		case EHOSTUNREACH:
8657 		case ENETDOWN:
8658 			if (TCPS_HAVERCVDSYN(tp->t_state)) {
8659 				tp->t_softerror = error;
8660 			}
8661 			/* FALLTHROUGH */
8662 		default:
8663 			slot = 10;
8664 			rack_start_hpts_timer(rack, tp, cts, __LINE__, slot, 0, 1);
8665 			tp->t_flags &= ~TF_FORCEDATA;
8666 			return (error);
8667 		}
8668 	} else {
8669 		rack->rc_enobuf = 0;
8670 	}
8671 	TCPSTAT_INC(tcps_sndtotal);
8672 
8673 	/*
8674 	 * Data sent (as far as we can tell). If this advertises a larger
8675 	 * window than any other segment, then remember the size of the
8676 	 * advertised window. Any pending ACK has now been sent.
8677 	 */
8678 	if (recwin > 0 && SEQ_GT(tp->rcv_nxt + recwin, tp->rcv_adv))
8679 		tp->rcv_adv = tp->rcv_nxt + recwin;
8680 	tp->last_ack_sent = tp->rcv_nxt;
8681 	tp->t_flags &= ~(TF_ACKNOW | TF_DELACK);
8682 enobufs:
8683 	rack->r_tlp_running = 0;
8684 	if ((flags & TH_RST) || (would_have_fin == 1)) {
8685 		/*
8686 		 * We don't send again after a RST. We also do *not* send
8687 		 * again if we would have had a find, but now have
8688 		 * outstanding data.
8689 		 */
8690 		slot = 0;
8691 		sendalot = 0;
8692 	}
8693 	if (slot) {
8694 		/* set the rack tcb into the slot N */
8695 		counter_u64_add(rack_paced_segments, 1);
8696 	} else if (sendalot) {
8697 		if (len)
8698 			counter_u64_add(rack_unpaced_segments, 1);
8699 		sack_rxmit = 0;
8700 		tp->t_flags &= ~TF_FORCEDATA;
8701 		goto again;
8702 	} else if (len) {
8703 		counter_u64_add(rack_unpaced_segments, 1);
8704 	}
8705 	tp->t_flags &= ~TF_FORCEDATA;
8706 	rack_start_hpts_timer(rack, tp, cts, __LINE__, slot, tot_len_this_send, 1);
8707 	return (error);
8708 }
8709 
8710 /*
8711  * rack_ctloutput() must drop the inpcb lock before performing copyin on
8712  * socket option arguments.  When it re-acquires the lock after the copy, it
8713  * has to revalidate that the connection is still valid for the socket
8714  * option.
8715  */
8716 static int
8717 rack_set_sockopt(struct socket *so, struct sockopt *sopt,
8718     struct inpcb *inp, struct tcpcb *tp, struct tcp_rack *rack)
8719 {
8720 	int32_t error = 0, optval;
8721 
8722 	switch (sopt->sopt_name) {
8723 	case TCP_RACK_PROP_RATE:
8724 	case TCP_RACK_PROP:
8725 	case TCP_RACK_TLP_REDUCE:
8726 	case TCP_RACK_EARLY_RECOV:
8727 	case TCP_RACK_PACE_ALWAYS:
8728 	case TCP_DELACK:
8729 	case TCP_RACK_PACE_REDUCE:
8730 	case TCP_RACK_PACE_MAX_SEG:
8731 	case TCP_RACK_PRR_SENDALOT:
8732 	case TCP_RACK_MIN_TO:
8733 	case TCP_RACK_EARLY_SEG:
8734 	case TCP_RACK_REORD_THRESH:
8735 	case TCP_RACK_REORD_FADE:
8736 	case TCP_RACK_TLP_THRESH:
8737 	case TCP_RACK_PKT_DELAY:
8738 	case TCP_RACK_TLP_USE:
8739 	case TCP_RACK_TLP_INC_VAR:
8740 	case TCP_RACK_IDLE_REDUCE_HIGH:
8741 	case TCP_RACK_MIN_PACE:
8742 	case TCP_RACK_MIN_PACE_SEG:
8743 	case TCP_BBR_RACK_RTT_USE:
8744 	case TCP_DATA_AFTER_CLOSE:
8745 		break;
8746 	default:
8747 		return (tcp_default_ctloutput(so, sopt, inp, tp));
8748 		break;
8749 	}
8750 	INP_WUNLOCK(inp);
8751 	error = sooptcopyin(sopt, &optval, sizeof(optval), sizeof(optval));
8752 	if (error)
8753 		return (error);
8754 	INP_WLOCK(inp);
8755 	if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
8756 		INP_WUNLOCK(inp);
8757 		return (ECONNRESET);
8758 	}
8759 	tp = intotcpcb(inp);
8760 	rack = (struct tcp_rack *)tp->t_fb_ptr;
8761 	switch (sopt->sopt_name) {
8762 	case TCP_RACK_PROP_RATE:
8763 		if ((optval <= 0) || (optval >= 100)) {
8764 			error = EINVAL;
8765 			break;
8766 		}
8767 		RACK_OPTS_INC(tcp_rack_prop_rate);
8768 		rack->r_ctl.rc_prop_rate = optval;
8769 		break;
8770 	case TCP_RACK_TLP_USE:
8771 		if ((optval < TLP_USE_ID) || (optval > TLP_USE_TWO_TWO)) {
8772 			error = EINVAL;
8773 			break;
8774 		}
8775 		RACK_OPTS_INC(tcp_tlp_use);
8776 		rack->rack_tlp_threshold_use = optval;
8777 		break;
8778 	case TCP_RACK_PROP:
8779 		/* RACK proportional rate reduction (bool) */
8780 		RACK_OPTS_INC(tcp_rack_prop);
8781 		rack->r_ctl.rc_prop_reduce = optval;
8782 		break;
8783 	case TCP_RACK_TLP_REDUCE:
8784 		/* RACK TLP cwnd reduction (bool) */
8785 		RACK_OPTS_INC(tcp_rack_tlp_reduce);
8786 		rack->r_ctl.rc_tlp_cwnd_reduce = optval;
8787 		break;
8788 	case TCP_RACK_EARLY_RECOV:
8789 		/* Should recovery happen early (bool) */
8790 		RACK_OPTS_INC(tcp_rack_early_recov);
8791 		rack->r_ctl.rc_early_recovery = optval;
8792 		break;
8793 	case TCP_RACK_PACE_ALWAYS:
8794 		/* Use the always pace method (bool)  */
8795 		RACK_OPTS_INC(tcp_rack_pace_always);
8796 		if (optval > 0)
8797 			rack->rc_always_pace = 1;
8798 		else
8799 			rack->rc_always_pace = 0;
8800 		break;
8801 	case TCP_RACK_PACE_REDUCE:
8802 		/* RACK Hptsi reduction factor (divisor) */
8803 		RACK_OPTS_INC(tcp_rack_pace_reduce);
8804 		if (optval)
8805 			/* Must be non-zero */
8806 			rack->rc_pace_reduce = optval;
8807 		else
8808 			error = EINVAL;
8809 		break;
8810 	case TCP_RACK_PACE_MAX_SEG:
8811 		/* Max segments in a pace */
8812 		RACK_OPTS_INC(tcp_rack_max_seg);
8813 		rack->rc_pace_max_segs = optval;
8814 		break;
8815 	case TCP_RACK_PRR_SENDALOT:
8816 		/* Allow PRR to send more than one seg */
8817 		RACK_OPTS_INC(tcp_rack_prr_sendalot);
8818 		rack->r_ctl.rc_prr_sendalot = optval;
8819 		break;
8820 	case TCP_RACK_MIN_TO:
8821 		/* Minimum time between rack t-o's in ms */
8822 		RACK_OPTS_INC(tcp_rack_min_to);
8823 		rack->r_ctl.rc_min_to = optval;
8824 		break;
8825 	case TCP_RACK_EARLY_SEG:
8826 		/* If early recovery max segments */
8827 		RACK_OPTS_INC(tcp_rack_early_seg);
8828 		rack->r_ctl.rc_early_recovery_segs = optval;
8829 		break;
8830 	case TCP_RACK_REORD_THRESH:
8831 		/* RACK reorder threshold (shift amount) */
8832 		RACK_OPTS_INC(tcp_rack_reord_thresh);
8833 		if ((optval > 0) && (optval < 31))
8834 			rack->r_ctl.rc_reorder_shift = optval;
8835 		else
8836 			error = EINVAL;
8837 		break;
8838 	case TCP_RACK_REORD_FADE:
8839 		/* Does reordering fade after ms time */
8840 		RACK_OPTS_INC(tcp_rack_reord_fade);
8841 		rack->r_ctl.rc_reorder_fade = optval;
8842 		break;
8843 	case TCP_RACK_TLP_THRESH:
8844 		/* RACK TLP theshold i.e. srtt+(srtt/N) */
8845 		RACK_OPTS_INC(tcp_rack_tlp_thresh);
8846 		if (optval)
8847 			rack->r_ctl.rc_tlp_threshold = optval;
8848 		else
8849 			error = EINVAL;
8850 		break;
8851 	case TCP_RACK_PKT_DELAY:
8852 		/* RACK added ms i.e. rack-rtt + reord + N */
8853 		RACK_OPTS_INC(tcp_rack_pkt_delay);
8854 		rack->r_ctl.rc_pkt_delay = optval;
8855 		break;
8856 	case TCP_RACK_TLP_INC_VAR:
8857 		/* Does TLP include rtt variance in t-o */
8858 		RACK_OPTS_INC(tcp_rack_tlp_inc_var);
8859 		rack->r_ctl.rc_prr_inc_var = optval;
8860 		break;
8861 	case TCP_RACK_IDLE_REDUCE_HIGH:
8862 		RACK_OPTS_INC(tcp_rack_idle_reduce_high);
8863 		if (optval)
8864 			rack->r_idle_reduce_largest = 1;
8865 		else
8866 			rack->r_idle_reduce_largest = 0;
8867 		break;
8868 	case TCP_DELACK:
8869 		if (optval == 0)
8870 			tp->t_delayed_ack = 0;
8871 		else
8872 			tp->t_delayed_ack = 1;
8873 		if (tp->t_flags & TF_DELACK) {
8874 			tp->t_flags &= ~TF_DELACK;
8875 			tp->t_flags |= TF_ACKNOW;
8876 			rack_output(tp);
8877 		}
8878 		break;
8879 	case TCP_RACK_MIN_PACE:
8880 		RACK_OPTS_INC(tcp_rack_min_pace);
8881 		if (optval > 3)
8882 			rack->r_enforce_min_pace = 3;
8883 		else
8884 			rack->r_enforce_min_pace = optval;
8885 		break;
8886 	case TCP_RACK_MIN_PACE_SEG:
8887 		RACK_OPTS_INC(tcp_rack_min_pace_seg);
8888 		if (optval >= 16)
8889 			rack->r_min_pace_seg_thresh = 15;
8890 		else
8891 			rack->r_min_pace_seg_thresh = optval;
8892 		break;
8893 	case TCP_BBR_RACK_RTT_USE:
8894 		if ((optval != USE_RTT_HIGH) &&
8895 		    (optval != USE_RTT_LOW) &&
8896 		    (optval != USE_RTT_AVG))
8897 			error = EINVAL;
8898 		else
8899 			rack->r_ctl.rc_rate_sample_method = optval;
8900 		break;
8901 	case TCP_DATA_AFTER_CLOSE:
8902 		if (optval)
8903 			rack->rc_allow_data_af_clo = 1;
8904 		else
8905 			rack->rc_allow_data_af_clo = 0;
8906 		break;
8907 	default:
8908 		return (tcp_default_ctloutput(so, sopt, inp, tp));
8909 		break;
8910 	}
8911 #ifdef NETFLIX_STATS
8912 	tcp_log_socket_option(tp, sopt->sopt_name, optval, error);
8913 #endif
8914 	INP_WUNLOCK(inp);
8915 	return (error);
8916 }
8917 
8918 static int
8919 rack_get_sockopt(struct socket *so, struct sockopt *sopt,
8920     struct inpcb *inp, struct tcpcb *tp, struct tcp_rack *rack)
8921 {
8922 	int32_t error, optval;
8923 
8924 	/*
8925 	 * Because all our options are either boolean or an int, we can just
8926 	 * pull everything into optval and then unlock and copy. If we ever
8927 	 * add a option that is not a int, then this will have quite an
8928 	 * impact to this routine.
8929 	 */
8930 	switch (sopt->sopt_name) {
8931 	case TCP_RACK_PROP_RATE:
8932 		optval = rack->r_ctl.rc_prop_rate;
8933 		break;
8934 	case TCP_RACK_PROP:
8935 		/* RACK proportional rate reduction (bool) */
8936 		optval = rack->r_ctl.rc_prop_reduce;
8937 		break;
8938 	case TCP_RACK_TLP_REDUCE:
8939 		/* RACK TLP cwnd reduction (bool) */
8940 		optval = rack->r_ctl.rc_tlp_cwnd_reduce;
8941 		break;
8942 	case TCP_RACK_EARLY_RECOV:
8943 		/* Should recovery happen early (bool) */
8944 		optval = rack->r_ctl.rc_early_recovery;
8945 		break;
8946 	case TCP_RACK_PACE_REDUCE:
8947 		/* RACK Hptsi reduction factor (divisor) */
8948 		optval = rack->rc_pace_reduce;
8949 		break;
8950 	case TCP_RACK_PACE_MAX_SEG:
8951 		/* Max segments in a pace */
8952 		optval = rack->rc_pace_max_segs;
8953 		break;
8954 	case TCP_RACK_PACE_ALWAYS:
8955 		/* Use the always pace method */
8956 		optval = rack->rc_always_pace;
8957 		break;
8958 	case TCP_RACK_PRR_SENDALOT:
8959 		/* Allow PRR to send more than one seg */
8960 		optval = rack->r_ctl.rc_prr_sendalot;
8961 		break;
8962 	case TCP_RACK_MIN_TO:
8963 		/* Minimum time between rack t-o's in ms */
8964 		optval = rack->r_ctl.rc_min_to;
8965 		break;
8966 	case TCP_RACK_EARLY_SEG:
8967 		/* If early recovery max segments */
8968 		optval = rack->r_ctl.rc_early_recovery_segs;
8969 		break;
8970 	case TCP_RACK_REORD_THRESH:
8971 		/* RACK reorder threshold (shift amount) */
8972 		optval = rack->r_ctl.rc_reorder_shift;
8973 		break;
8974 	case TCP_RACK_REORD_FADE:
8975 		/* Does reordering fade after ms time */
8976 		optval = rack->r_ctl.rc_reorder_fade;
8977 		break;
8978 	case TCP_RACK_TLP_THRESH:
8979 		/* RACK TLP theshold i.e. srtt+(srtt/N) */
8980 		optval = rack->r_ctl.rc_tlp_threshold;
8981 		break;
8982 	case TCP_RACK_PKT_DELAY:
8983 		/* RACK added ms i.e. rack-rtt + reord + N */
8984 		optval = rack->r_ctl.rc_pkt_delay;
8985 		break;
8986 	case TCP_RACK_TLP_USE:
8987 		optval = rack->rack_tlp_threshold_use;
8988 		break;
8989 	case TCP_RACK_TLP_INC_VAR:
8990 		/* Does TLP include rtt variance in t-o */
8991 		optval = rack->r_ctl.rc_prr_inc_var;
8992 		break;
8993 	case TCP_RACK_IDLE_REDUCE_HIGH:
8994 		optval = rack->r_idle_reduce_largest;
8995 		break;
8996 	case TCP_RACK_MIN_PACE:
8997 		optval = rack->r_enforce_min_pace;
8998 		break;
8999 	case TCP_RACK_MIN_PACE_SEG:
9000 		optval = rack->r_min_pace_seg_thresh;
9001 		break;
9002 	case TCP_BBR_RACK_RTT_USE:
9003 		optval = rack->r_ctl.rc_rate_sample_method;
9004 		break;
9005 	case TCP_DELACK:
9006 		optval = tp->t_delayed_ack;
9007 		break;
9008 	case TCP_DATA_AFTER_CLOSE:
9009 		optval = rack->rc_allow_data_af_clo;
9010 		break;
9011 	default:
9012 		return (tcp_default_ctloutput(so, sopt, inp, tp));
9013 		break;
9014 	}
9015 	INP_WUNLOCK(inp);
9016 	error = sooptcopyout(sopt, &optval, sizeof optval);
9017 	return (error);
9018 }
9019 
9020 static int
9021 rack_ctloutput(struct socket *so, struct sockopt *sopt, struct inpcb *inp, struct tcpcb *tp)
9022 {
9023 	int32_t error = EINVAL;
9024 	struct tcp_rack *rack;
9025 
9026 	rack = (struct tcp_rack *)tp->t_fb_ptr;
9027 	if (rack == NULL) {
9028 		/* Huh? */
9029 		goto out;
9030 	}
9031 	if (sopt->sopt_dir == SOPT_SET) {
9032 		return (rack_set_sockopt(so, sopt, inp, tp, rack));
9033 	} else if (sopt->sopt_dir == SOPT_GET) {
9034 		return (rack_get_sockopt(so, sopt, inp, tp, rack));
9035 	}
9036 out:
9037 	INP_WUNLOCK(inp);
9038 	return (error);
9039 }
9040 
9041 
9042 struct tcp_function_block __tcp_rack = {
9043 	.tfb_tcp_block_name = __XSTRING(STACKNAME),
9044 	.tfb_tcp_output = rack_output,
9045 	.tfb_tcp_do_segment = rack_do_segment,
9046 	.tfb_tcp_hpts_do_segment = rack_hpts_do_segment,
9047 	.tfb_tcp_ctloutput = rack_ctloutput,
9048 	.tfb_tcp_fb_init = rack_init,
9049 	.tfb_tcp_fb_fini = rack_fini,
9050 	.tfb_tcp_timer_stop_all = rack_stopall,
9051 	.tfb_tcp_timer_activate = rack_timer_activate,
9052 	.tfb_tcp_timer_active = rack_timer_active,
9053 	.tfb_tcp_timer_stop = rack_timer_stop,
9054 	.tfb_tcp_rexmit_tmr = rack_remxt_tmr,
9055 	.tfb_tcp_handoff_ok = rack_handoff_ok
9056 };
9057 
9058 static const char *rack_stack_names[] = {
9059 	__XSTRING(STACKNAME),
9060 #ifdef STACKALIAS
9061 	__XSTRING(STACKALIAS),
9062 #endif
9063 };
9064 
9065 static int
9066 rack_ctor(void *mem, int32_t size, void *arg, int32_t how)
9067 {
9068 	memset(mem, 0, size);
9069 	return (0);
9070 }
9071 
9072 static void
9073 rack_dtor(void *mem, int32_t size, void *arg)
9074 {
9075 
9076 }
9077 
9078 static bool rack_mod_inited = false;
9079 
9080 static int
9081 tcp_addrack(module_t mod, int32_t type, void *data)
9082 {
9083 	int32_t err = 0;
9084 	int num_stacks;
9085 
9086 	switch (type) {
9087 	case MOD_LOAD:
9088 		rack_zone = uma_zcreate(__XSTRING(MODNAME) "_map",
9089 		    sizeof(struct rack_sendmap),
9090 		    rack_ctor, rack_dtor, NULL, NULL, UMA_ALIGN_PTR, 0);
9091 
9092 		rack_pcb_zone = uma_zcreate(__XSTRING(MODNAME) "_pcb",
9093 		    sizeof(struct tcp_rack),
9094 		    rack_ctor, NULL, NULL, NULL, UMA_ALIGN_CACHE, 0);
9095 
9096 		sysctl_ctx_init(&rack_sysctl_ctx);
9097 		rack_sysctl_root = SYSCTL_ADD_NODE(&rack_sysctl_ctx,
9098 		    SYSCTL_STATIC_CHILDREN(_net_inet_tcp),
9099 		    OID_AUTO,
9100 		    __XSTRING(STACKNAME),
9101 		    CTLFLAG_RW, 0,
9102 		    "");
9103 		if (rack_sysctl_root == NULL) {
9104 			printf("Failed to add sysctl node\n");
9105 			err = EFAULT;
9106 			goto free_uma;
9107 		}
9108 		rack_init_sysctls();
9109 		num_stacks = nitems(rack_stack_names);
9110 		err = register_tcp_functions_as_names(&__tcp_rack, M_WAITOK,
9111 		    rack_stack_names, &num_stacks);
9112 		if (err) {
9113 			printf("Failed to register %s stack name for "
9114 			    "%s module\n", rack_stack_names[num_stacks],
9115 			    __XSTRING(MODNAME));
9116 			sysctl_ctx_free(&rack_sysctl_ctx);
9117 free_uma:
9118 			uma_zdestroy(rack_zone);
9119 			uma_zdestroy(rack_pcb_zone);
9120 			rack_counter_destroy();
9121 			printf("Failed to register rack module -- err:%d\n", err);
9122 			return (err);
9123 		}
9124 		rack_mod_inited = true;
9125 		break;
9126 	case MOD_QUIESCE:
9127 		err = deregister_tcp_functions(&__tcp_rack, true, false);
9128 		break;
9129 	case MOD_UNLOAD:
9130 		err = deregister_tcp_functions(&__tcp_rack, false, true);
9131 		if (err == EBUSY)
9132 			break;
9133 		if (rack_mod_inited) {
9134 			uma_zdestroy(rack_zone);
9135 			uma_zdestroy(rack_pcb_zone);
9136 			sysctl_ctx_free(&rack_sysctl_ctx);
9137 			rack_counter_destroy();
9138 			rack_mod_inited = false;
9139 		}
9140 		err = 0;
9141 		break;
9142 	default:
9143 		return (EOPNOTSUPP);
9144 	}
9145 	return (err);
9146 }
9147 
9148 static moduledata_t tcp_rack = {
9149 	.name = __XSTRING(MODNAME),
9150 	.evhand = tcp_addrack,
9151 	.priv = 0
9152 };
9153 
9154 MODULE_VERSION(MODNAME, 1);
9155 DECLARE_MODULE(MODNAME, tcp_rack, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY);
9156 MODULE_DEPEND(MODNAME, tcphpts, 1, 1, 1);
9157