xref: /dragonfly/sys/netinet/tcp_usrreq.c (revision 245bd6bc)
1 /*
2  * Copyright (c) 2003, 2004 Jeffrey M. Hsu.  All rights reserved.
3  * Copyright (c) 2003, 2004 The DragonFly Project.  All rights reserved.
4  *
5  * This code is derived from software contributed to The DragonFly Project
6  * by Jeffrey M. Hsu.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. Neither the name of The DragonFly Project nor the names of its
17  *    contributors may be used to endorse or promote products derived
18  *    from this software without specific, prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
21  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
23  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
24  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
25  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
26  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
27  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
28  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
29  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
30  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 /*
35  * Copyright (c) 1982, 1986, 1988, 1993
36  *	The Regents of the University of California.  All rights reserved.
37  *
38  * Redistribution and use in source and binary forms, with or without
39  * modification, are permitted provided that the following conditions
40  * are met:
41  * 1. Redistributions of source code must retain the above copyright
42  *    notice, this list of conditions and the following disclaimer.
43  * 2. Redistributions in binary form must reproduce the above copyright
44  *    notice, this list of conditions and the following disclaimer in the
45  *    documentation and/or other materials provided with the distribution.
46  * 3. Neither the name of the University nor the names of its contributors
47  *    may be used to endorse or promote products derived from this software
48  *    without specific prior written permission.
49  *
50  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
51  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
52  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
53  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
54  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
55  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
56  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
57  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
58  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
59  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
60  * SUCH DAMAGE.
61  *
62  *	From: @(#)tcp_usrreq.c	8.2 (Berkeley) 1/3/94
63  * $FreeBSD: src/sys/netinet/tcp_usrreq.c,v 1.51.2.17 2002/10/11 11:46:44 ume Exp $
64  */
65 
66 #include "opt_inet.h"
67 #include "opt_inet6.h"
68 #include "opt_tcpdebug.h"
69 
70 #include <sys/param.h>
71 #include <sys/systm.h>
72 #include <sys/kernel.h>
73 #include <sys/malloc.h>
74 #include <sys/sysctl.h>
75 #include <sys/globaldata.h>
76 #include <sys/thread.h>
77 
78 #include <sys/mbuf.h>
79 #ifdef INET6
80 #include <sys/domain.h>
81 #endif /* INET6 */
82 #include <sys/socket.h>
83 #include <sys/socketvar.h>
84 #include <sys/socketops.h>
85 #include <sys/protosw.h>
86 #include <sys/jail.h>
87 
88 #include <sys/msgport2.h>
89 #include <sys/socketvar2.h>
90 
91 #include <net/if.h>
92 #include <net/netisr.h>
93 #include <net/route.h>
94 
95 #include <net/netmsg2.h>
96 #include <net/netisr2.h>
97 
98 #include <netinet/in.h>
99 #include <netinet/in_systm.h>
100 #ifdef INET6
101 #include <netinet/ip6.h>
102 #endif
103 #include <netinet/in_pcb.h>
104 #ifdef INET6
105 #include <netinet6/in6_pcb.h>
106 #endif
107 #include <netinet/in_var.h>
108 #include <netinet/ip_var.h>
109 #ifdef INET6
110 #include <netinet6/ip6_var.h>
111 #include <netinet6/tcp6_var.h>
112 #endif
113 #include <netinet/tcp.h>
114 #include <netinet/tcp_fsm.h>
115 #include <netinet/tcp_seq.h>
116 #include <netinet/tcp_timer.h>
117 #include <netinet/tcp_timer2.h>
118 #include <netinet/tcp_var.h>
119 #include <netinet/tcpip.h>
120 #ifdef TCPDEBUG
121 #include <netinet/tcp_debug.h>
122 #endif
123 #include <machine/limits.h>
124 
125 /*
126  * Limits for TCP_KEEP* options (we will adopt the same limits that linux
127  * uses).
128  */
129 #define MAXKEEPALIVE		32767
130 #define MAXKEEPCNT		127
131 
132 /*
133  * TCP protocol interface to socket abstraction.
134  */
135 extern	char *tcpstates[];	/* XXX ??? */
136 
137 static int	tcp_attach (struct socket *, struct pru_attach_info *);
138 static void	tcp_connect (netmsg_t msg);
139 #ifdef INET6
140 static void	tcp6_connect (netmsg_t msg);
141 static int	tcp6_connect_oncpu(struct tcpcb *tp, int flags,
142 				struct mbuf **mp,
143 				struct sockaddr_in6 *sin6,
144 				struct in6_addr *addr6);
145 #endif /* INET6 */
146 static struct tcpcb *
147 		tcp_disconnect (struct tcpcb *);
148 static struct tcpcb *
149 		tcp_usrclosed (struct tcpcb *);
150 
151 #ifdef TCPDEBUG
152 #define	TCPDEBUG0	int ostate = 0
153 #define	TCPDEBUG1()	ostate = tp ? tp->t_state : 0
154 #define	TCPDEBUG2(req)	if (tp && (so->so_options & SO_DEBUG)) \
155 				tcp_trace(TA_USER, ostate, tp, 0, 0, req)
156 #else
157 #define	TCPDEBUG0
158 #define	TCPDEBUG1()
159 #define	TCPDEBUG2(req)
160 #endif
161 
162 /*
163  * For some ill optimized programs, which try to use TCP_NOPUSH
164  * to improve performance, will have small amount of data sits
165  * in the sending buffer.  These small amount of data will _not_
166  * be pushed into the network until more data are written into
167  * the socket or the socket write side is shutdown.
168  */
169 static int	tcp_disable_nopush = 1;
170 SYSCTL_INT(_net_inet_tcp, OID_AUTO, disable_nopush, CTLFLAG_RW,
171     &tcp_disable_nopush, 0, "TCP_NOPUSH socket option will have no effect");
172 
173 /*
174  * Allocate socket buffer space.
175  */
176 static int
177 tcp_usr_preattach(struct socket *so, int proto __unused,
178     struct pru_attach_info *ai)
179 {
180 	int error;
181 
182 	if (so->so_snd.ssb_hiwat == 0 || so->so_rcv.ssb_hiwat == 0) {
183 		error = soreserve(so, tcp_sendspace, tcp_recvspace,
184 				  ai->sb_rlimit);
185 		if (error)
186 			return (error);
187 	}
188 	atomic_set_int(&so->so_rcv.ssb_flags, SSB_AUTOSIZE);
189 	atomic_set_int(&so->so_snd.ssb_flags, SSB_AUTOSIZE | SSB_PREALLOC);
190 
191 	return 0;
192 }
193 
194 /*
195  * TCP attaches to socket via pru_attach(), reserving space,
196  * and an internet control block.  This socket may move to
197  * other CPU later when we bind/connect.
198  */
199 static void
200 tcp_usr_attach(netmsg_t msg)
201 {
202 	struct socket *so = msg->base.nm_so;
203 	struct pru_attach_info *ai = msg->attach.nm_ai;
204 	int error;
205 	struct inpcb *inp;
206 	struct tcpcb *tp = NULL;
207 	TCPDEBUG0;
208 
209 	inp = so->so_pcb;
210 	KASSERT(inp == NULL, ("tcp socket attached"));
211 	TCPDEBUG1();
212 
213 	error = tcp_attach(so, ai);
214 	if (error)
215 		goto out;
216 
217 	if ((so->so_options & SO_LINGER) && so->so_linger == 0)
218 		so->so_linger = TCP_LINGERTIME;
219 	tp = sototcpcb(so);
220 out:
221 	TCPDEBUG2(PRU_ATTACH);
222 	lwkt_replymsg(&msg->lmsg, error);
223 }
224 
225 /*
226  * pru_detach() detaches the TCP protocol from the socket.
227  * If the protocol state is non-embryonic, then can't
228  * do this directly: have to initiate a pru_disconnect(),
229  * which may finish later; embryonic TCB's can just
230  * be discarded here.
231  */
232 static void
233 tcp_usr_detach(netmsg_t msg)
234 {
235 	struct socket *so = msg->base.nm_so;
236 	int error = 0;
237 	struct inpcb *inp;
238 	struct tcpcb *tp;
239 	TCPDEBUG0;
240 
241 	inp = so->so_pcb;
242 
243 	/*
244 	 * If the inp is already detached or never attached, it may have
245 	 * been due to an async close or async attach failure.  Just return
246 	 * as if no error occured.
247 	 */
248 	if (inp) {
249 		tp = intotcpcb(inp);
250 		KASSERT(tp != NULL, ("tcp_usr_detach: tp is NULL"));
251 		TCPDEBUG1();
252 		tp = tcp_disconnect(tp);
253 		TCPDEBUG2(PRU_DETACH);
254 	}
255 	lwkt_replymsg(&msg->lmsg, error);
256 }
257 
258 /*
259  * NOTE: ignore_error is non-zero for certain disconnection races
260  * which we want to silently allow, otherwise close() may return
261  * an unexpected error.
262  *
263  * NOTE: The variables (msg) and (tp) are assumed.
264  */
265 #define	COMMON_START(so, inp, ignore_error)			\
266 	TCPDEBUG0; 						\
267 								\
268 	inp = so->so_pcb; 					\
269 	do {							\
270 		if (inp == NULL) {				\
271 			error = ignore_error ? 0 : EINVAL;	\
272 			tp = NULL;				\
273 			goto out;				\
274 		}						\
275 		tp = intotcpcb(inp);				\
276 		TCPDEBUG1();					\
277 	} while(0)
278 
279 #define COMMON_END1(req, noreply)				\
280 	out: do {						\
281 		TCPDEBUG2(req);					\
282 		if (!(noreply))					\
283 			lwkt_replymsg(&msg->lmsg, error);	\
284 		return;						\
285 	} while(0)
286 
287 #define COMMON_END(req)		COMMON_END1((req), 0)
288 
289 static void
290 tcp_sosetport(struct lwkt_msg *msg, lwkt_port_t port)
291 {
292 	sosetport(((struct netmsg_base *)msg)->nm_so, port);
293 }
294 
295 /*
296  * Give the socket an address.
297  */
298 static void
299 tcp_usr_bind(netmsg_t msg)
300 {
301 	struct socket *so = msg->bind.base.nm_so;
302 	struct sockaddr *nam = msg->bind.nm_nam;
303 	struct thread *td = msg->bind.nm_td;
304 	int error = 0;
305 	struct inpcb *inp;
306 	struct tcpcb *tp;
307 	struct sockaddr_in *sinp;
308 	lwkt_port_t port0 = netisr_cpuport(0);
309 
310 	COMMON_START(so, inp, 0);
311 
312 	/*
313 	 * Must check for multicast addresses and disallow binding
314 	 * to them.
315 	 */
316 	sinp = (struct sockaddr_in *)nam;
317 	if (sinp->sin_family == AF_INET &&
318 	    IN_MULTICAST(ntohl(sinp->sin_addr.s_addr))) {
319 		error = EAFNOSUPPORT;
320 		goto out;
321 	}
322 
323 	/*
324 	 * Check "already bound" here (in_pcbbind() does the same check
325 	 * though), so we don't forward a connected socket to netisr0,
326 	 * which would panic in the following in_pcbunlink().
327 	 */
328 	if (inp->inp_lport != 0 || inp->inp_laddr.s_addr != INADDR_ANY) {
329 		error = EINVAL;	/* already bound */
330 		goto out;
331 	}
332 
333 	/*
334 	 * Use netisr0 to serialize in_pcbbind(), so that pru_detach and
335 	 * pru_bind for different sockets on the same local port could be
336 	 * properly ordered.  The original race is illustrated here for
337 	 * reference.
338 	 *
339 	 * s1 = socket();
340 	 * bind(s1, *.PORT);
341 	 * close(s1);  <----- asynchronous
342 	 * s2 = socket();
343 	 * bind(s2, *.PORT);
344 	 *
345 	 * All will expect bind(s2, *.PORT) to succeed.  However, it will
346 	 * fail, if following sequence happens due to random socket initial
347 	 * msgport and asynchronous close(2):
348 	 *
349 	 *    netisrN                  netisrM
350 	 *       :                        :
351 	 *       :                    pru_bind(s2) [*.PORT is used by s1]
352 	 *  pru_detach(s1)                :
353 	 */
354 	if (&curthread->td_msgport != port0) {
355 		lwkt_msg_t lmsg = &msg->bind.base.lmsg;
356 
357 		KASSERT((msg->bind.nm_flags & PRUB_RELINK) == 0,
358 		    ("already asked to relink"));
359 
360 		in_pcbunlink(so->so_pcb, &tcbinfo[mycpuid]);
361 		msg->bind.nm_flags |= PRUB_RELINK;
362 
363 		TCP_STATE_MIGRATE_START(tp);
364 
365 		/* See the related comment in tcp_connect() */
366 		lwkt_setmsg_receipt(lmsg, tcp_sosetport);
367 		lwkt_forwardmsg(port0, lmsg);
368 		/* msg invalid now */
369 		return;
370 	}
371 	KASSERT(so->so_port == port0, ("so_port is not netisr0"));
372 
373 	if (msg->bind.nm_flags & PRUB_RELINK) {
374 		msg->bind.nm_flags &= ~PRUB_RELINK;
375 		TCP_STATE_MIGRATE_END(tp);
376 		in_pcblink(so->so_pcb, &tcbinfo[mycpuid]);
377 	}
378 	KASSERT(inp->inp_pcbinfo == &tcbinfo[0], ("pcbinfo is not tcbinfo0"));
379 
380 	error = in_pcbbind(inp, nam, td);
381 	if (error)
382 		goto out;
383 
384 	COMMON_END(PRU_BIND);
385 }
386 
387 #ifdef INET6
388 
389 static void
390 tcp6_usr_bind(netmsg_t msg)
391 {
392 	struct socket *so = msg->bind.base.nm_so;
393 	struct sockaddr *nam = msg->bind.nm_nam;
394 	struct thread *td = msg->bind.nm_td;
395 	int error = 0;
396 	struct inpcb *inp;
397 	struct tcpcb *tp;
398 	struct sockaddr_in6 *sin6p;
399 
400 	COMMON_START(so, inp, 0);
401 
402 	/*
403 	 * Must check for multicast addresses and disallow binding
404 	 * to them.
405 	 */
406 	sin6p = (struct sockaddr_in6 *)nam;
407 	if (sin6p->sin6_family == AF_INET6 &&
408 	    IN6_IS_ADDR_MULTICAST(&sin6p->sin6_addr)) {
409 		error = EAFNOSUPPORT;
410 		goto out;
411 	}
412 	error = in6_pcbbind(inp, nam, td);
413 	if (error)
414 		goto out;
415 	COMMON_END(PRU_BIND);
416 }
417 #endif /* INET6 */
418 
419 struct netmsg_inswildcard {
420 	struct netmsg_base	base;
421 	struct inpcb		*nm_inp;
422 };
423 
424 static void
425 in_pcbinswildcardhash_handler(netmsg_t msg)
426 {
427 	struct netmsg_inswildcard *nm = (struct netmsg_inswildcard *)msg;
428 	int cpu = mycpuid, nextcpu;
429 
430 	in_pcbinswildcardhash_oncpu(nm->nm_inp, &tcbinfo[cpu]);
431 
432 	nextcpu = cpu + 1;
433 	if (nextcpu < netisr_ncpus)
434 		lwkt_forwardmsg(netisr_cpuport(nextcpu), &nm->base.lmsg);
435 	else
436 		lwkt_replymsg(&nm->base.lmsg, 0);
437 }
438 
439 /*
440  * Prepare to accept connections.
441  */
442 static void
443 tcp_usr_listen(netmsg_t msg)
444 {
445 	struct socket *so = msg->listen.base.nm_so;
446 	struct thread *td = msg->listen.nm_td;
447 	int error = 0;
448 	struct inpcb *inp;
449 	struct tcpcb *tp;
450 	struct netmsg_inswildcard nm;
451 	lwkt_port_t port0 = netisr_cpuport(0);
452 
453 	COMMON_START(so, inp, 0);
454 
455 	if (&curthread->td_msgport != port0) {
456 		lwkt_msg_t lmsg = &msg->listen.base.lmsg;
457 
458 		KASSERT((msg->listen.nm_flags & PRUL_RELINK) == 0,
459 		    ("already asked to relink"));
460 
461 		in_pcbunlink(so->so_pcb, &tcbinfo[mycpuid]);
462 		msg->listen.nm_flags |= PRUL_RELINK;
463 
464 		TCP_STATE_MIGRATE_START(tp);
465 
466 		/* See the related comment in tcp_connect() */
467 		lwkt_setmsg_receipt(lmsg, tcp_sosetport);
468 		lwkt_forwardmsg(port0, lmsg);
469 		/* msg invalid now */
470 		return;
471 	}
472 	KASSERT(so->so_port == port0, ("so_port is not netisr0"));
473 
474 	if (msg->listen.nm_flags & PRUL_RELINK) {
475 		msg->listen.nm_flags &= ~PRUL_RELINK;
476 		TCP_STATE_MIGRATE_END(tp);
477 		in_pcblink(so->so_pcb, &tcbinfo[mycpuid]);
478 	}
479 	KASSERT(inp->inp_pcbinfo == &tcbinfo[0], ("pcbinfo is not tcbinfo0"));
480 
481 	if (tp->t_flags & TF_LISTEN)
482 		goto out;
483 
484 	if (inp->inp_lport == 0) {
485 		error = in_pcbbind(inp, NULL, td);
486 		if (error)
487 			goto out;
488 	}
489 
490 	TCP_STATE_CHANGE(tp, TCPS_LISTEN);
491 	tp->t_flags |= TF_LISTEN;
492 	tp->tt_msg = NULL; /* Catch any invalid timer usage */
493 
494 	/*
495 	 * Create tcpcb per-cpu port cache
496 	 *
497 	 * NOTE:
498 	 * This _must_ be done before installing this inpcb into
499 	 * wildcard hash.
500 	 */
501 	tcp_pcbport_create(tp);
502 
503 	if (netisr_ncpus > 1) {
504 		/*
505 		 * Put this inpcb into wildcard hash on other cpus.
506 		 */
507 		ASSERT_INP_NOTINHASH(inp);
508 		netmsg_init(&nm.base, NULL, &curthread->td_msgport,
509 			    MSGF_PRIORITY, in_pcbinswildcardhash_handler);
510 		nm.nm_inp = inp;
511 		lwkt_domsg(netisr_cpuport(1), &nm.base.lmsg, 0);
512 	}
513 	in_pcbinswildcardhash(inp);
514 	COMMON_END(PRU_LISTEN);
515 }
516 
517 #ifdef INET6
518 
519 static void
520 tcp6_usr_listen(netmsg_t msg)
521 {
522 	struct socket *so = msg->listen.base.nm_so;
523 	struct thread *td = msg->listen.nm_td;
524 	int error = 0;
525 	struct inpcb *inp;
526 	struct tcpcb *tp;
527 	struct netmsg_inswildcard nm;
528 
529 	COMMON_START(so, inp, 0);
530 
531 	if (tp->t_flags & TF_LISTEN)
532 		goto out;
533 
534 	if (inp->inp_lport == 0) {
535 		error = in6_pcbbind(inp, NULL, td);
536 		if (error)
537 			goto out;
538 	}
539 
540 	TCP_STATE_CHANGE(tp, TCPS_LISTEN);
541 	tp->t_flags |= TF_LISTEN;
542 	tp->tt_msg = NULL; /* Catch any invalid timer usage */
543 
544 	/*
545 	 * Create tcpcb per-cpu port cache
546 	 *
547 	 * NOTE:
548 	 * This _must_ be done before installing this inpcb into
549 	 * wildcard hash.
550 	 */
551 	tcp_pcbport_create(tp);
552 
553 	if (netisr_ncpus > 1) {
554 		/*
555 		 * Put this inpcb into wildcard hash on other cpus.
556 		 */
557 		KKASSERT(so->so_port == netisr_cpuport(0));
558 		ASSERT_NETISR0;
559 		KKASSERT(inp->inp_pcbinfo == &tcbinfo[0]);
560 		ASSERT_INP_NOTINHASH(inp);
561 
562 		netmsg_init(&nm.base, NULL, &curthread->td_msgport,
563 			    MSGF_PRIORITY, in_pcbinswildcardhash_handler);
564 		nm.nm_inp = inp;
565 		lwkt_domsg(netisr_cpuport(1), &nm.base.lmsg, 0);
566 	}
567 	in_pcbinswildcardhash(inp);
568 	COMMON_END(PRU_LISTEN);
569 }
570 #endif /* INET6 */
571 
572 /*
573  * Initiate connection to peer.
574  * Create a template for use in transmissions on this connection.
575  * Enter SYN_SENT state, and mark socket as connecting.
576  * Start keep-alive timer, and seed output sequence space.
577  * Send initial segment on connection.
578  */
579 static void
580 tcp_usr_connect(netmsg_t msg)
581 {
582 	struct socket *so = msg->connect.base.nm_so;
583 	struct sockaddr *nam = msg->connect.nm_nam;
584 	struct thread *td = msg->connect.nm_td;
585 	int error = 0;
586 	struct inpcb *inp;
587 	struct tcpcb *tp;
588 	struct sockaddr_in *sinp;
589 
590 	ASSERT_NETISR_NCPUS(mycpuid);
591 
592 	COMMON_START(so, inp, 0);
593 
594 	/*
595 	 * Must disallow TCP ``connections'' to multicast addresses.
596 	 */
597 	sinp = (struct sockaddr_in *)nam;
598 	if (sinp->sin_family == AF_INET
599 	    && IN_MULTICAST(ntohl(sinp->sin_addr.s_addr))) {
600 		error = EAFNOSUPPORT;
601 		goto out;
602 	}
603 	tcp_connect(msg);
604 	/* msg is invalid now */
605 	return;
606 out:
607 	if (msg->connect.nm_m) {
608 		m_freem(msg->connect.nm_m);
609 		msg->connect.nm_m = NULL;
610 	}
611 	if (msg->connect.nm_flags & PRUC_HELDTD)
612 		lwkt_rele(td);
613 	if (error && (msg->connect.nm_flags & PRUC_ASYNC)) {
614 		so->so_error = error;
615 		soisdisconnected(so);
616 	}
617 	lwkt_replymsg(&msg->lmsg, error);
618 }
619 
620 #ifdef INET6
621 
622 static void
623 tcp6_usr_connect(netmsg_t msg)
624 {
625 	struct socket *so = msg->connect.base.nm_so;
626 	struct sockaddr *nam = msg->connect.nm_nam;
627 	struct thread *td = msg->connect.nm_td;
628 	int error = 0;
629 	struct inpcb *inp;
630 	struct tcpcb *tp;
631 	struct sockaddr_in6 *sin6p;
632 
633 	ASSERT_NETISR_NCPUS(mycpuid);
634 
635 	COMMON_START(so, inp, 0);
636 
637 	/*
638 	 * Must disallow TCP ``connections'' to multicast addresses.
639 	 */
640 	sin6p = (struct sockaddr_in6 *)nam;
641 	if (sin6p->sin6_family == AF_INET6
642 	    && IN6_IS_ADDR_MULTICAST(&sin6p->sin6_addr)) {
643 		error = EAFNOSUPPORT;
644 		goto out;
645 	}
646 
647 	if (!prison_remote_ip(td, nam)) {
648 		error = EAFNOSUPPORT;	/* Illegal jail IP */
649 		goto out;
650 	}
651 
652 	/* Reject v4-mapped address */
653 	if (IN6_IS_ADDR_V4MAPPED(&sin6p->sin6_addr)) {
654 		error = EADDRNOTAVAIL;
655 		goto out;
656 	}
657 
658 	inp->inp_inc.inc_isipv6 = 1;
659 	tcp6_connect(msg);
660 	/* msg is invalid now */
661 	return;
662 out:
663 	if (msg->connect.nm_m) {
664 		m_freem(msg->connect.nm_m);
665 		msg->connect.nm_m = NULL;
666 	}
667 	lwkt_replymsg(&msg->lmsg, error);
668 }
669 
670 #endif /* INET6 */
671 
672 /*
673  * Initiate disconnect from peer.
674  * If connection never passed embryonic stage, just drop;
675  * else if don't need to let data drain, then can just drop anyways,
676  * else have to begin TCP shutdown process: mark socket disconnecting,
677  * drain unread data, state switch to reflect user close, and
678  * send segment (e.g. FIN) to peer.  Socket will be really disconnected
679  * when peer sends FIN and acks ours.
680  *
681  * SHOULD IMPLEMENT LATER PRU_CONNECT VIA REALLOC TCPCB.
682  */
683 static void
684 tcp_usr_disconnect(netmsg_t msg)
685 {
686 	struct socket *so = msg->disconnect.base.nm_so;
687 	int error = 0;
688 	struct inpcb *inp;
689 	struct tcpcb *tp;
690 
691 	COMMON_START(so, inp, 1);
692 	tp = tcp_disconnect(tp);
693 	COMMON_END(PRU_DISCONNECT);
694 }
695 
696 /*
697  * Accept a connection.  Essentially all the work is
698  * done at higher levels; just return the address
699  * of the peer, storing through addr.
700  */
701 static void
702 tcp_usr_accept(netmsg_t msg)
703 {
704 	struct socket *so = msg->accept.base.nm_so;
705 	struct sockaddr **nam = msg->accept.nm_nam;
706 	int error = 0;
707 	struct inpcb *inp;
708 	struct tcpcb *tp = NULL;
709 	TCPDEBUG0;
710 
711 	inp = so->so_pcb;
712 	if (so->so_state & SS_ISDISCONNECTED) {
713 		error = ECONNABORTED;
714 		goto out;
715 	}
716 	if (inp == NULL) {
717 		error = EINVAL;
718 		goto out;
719 	}
720 
721 	tp = intotcpcb(inp);
722 	TCPDEBUG1();
723 	in_setpeeraddr(so, nam);
724 	COMMON_END(PRU_ACCEPT);
725 }
726 
727 #ifdef INET6
728 static void
729 tcp6_usr_accept(netmsg_t msg)
730 {
731 	struct socket *so = msg->accept.base.nm_so;
732 	struct sockaddr **nam = msg->accept.nm_nam;
733 	int error = 0;
734 	struct inpcb *inp;
735 	struct tcpcb *tp = NULL;
736 	TCPDEBUG0;
737 
738 	inp = so->so_pcb;
739 
740 	if (so->so_state & SS_ISDISCONNECTED) {
741 		error = ECONNABORTED;
742 		goto out;
743 	}
744 	if (inp == NULL) {
745 		error = EINVAL;
746 		goto out;
747 	}
748 	tp = intotcpcb(inp);
749 	TCPDEBUG1();
750 	in6_setpeeraddr(so, nam);
751 	COMMON_END(PRU_ACCEPT);
752 }
753 #endif /* INET6 */
754 
755 /*
756  * Mark the connection as being incapable of further output.
757  */
758 static void
759 tcp_usr_shutdown(netmsg_t msg)
760 {
761 	struct socket *so = msg->shutdown.base.nm_so;
762 	int error = 0;
763 	struct inpcb *inp;
764 	struct tcpcb *tp;
765 
766 	COMMON_START(so, inp, 0);
767 	socantsendmore(so);
768 	tp = tcp_usrclosed(tp);
769 	if (tp)
770 		error = tcp_output(tp);
771 	COMMON_END(PRU_SHUTDOWN);
772 }
773 
774 /*
775  * After a receive, possibly send window update to peer.
776  */
777 static void
778 tcp_usr_rcvd(netmsg_t msg)
779 {
780 	struct socket *so = msg->rcvd.base.nm_so;
781 	int error = 0, noreply = 0;
782 	struct inpcb *inp;
783 	struct tcpcb *tp;
784 
785 	COMMON_START(so, inp, 0);
786 
787 	if (msg->rcvd.nm_pru_flags & PRUR_ASYNC) {
788 		noreply = 1;
789 		so_async_rcvd_reply(so);
790 	}
791 	tcp_output(tp);
792 
793 	COMMON_END1(PRU_RCVD, noreply);
794 }
795 
796 /*
797  * Do a send by putting data in output queue and updating urgent
798  * marker if URG set.  Possibly send more data.  Unlike the other
799  * pru_*() routines, the mbuf chains are our responsibility.  We
800  * must either enqueue them or free them.  The other pru_* routines
801  * generally are caller-frees.
802  */
803 static void
804 tcp_usr_send(netmsg_t msg)
805 {
806 	struct socket *so = msg->send.base.nm_so;
807 	int flags = msg->send.nm_flags;
808 	struct mbuf *m = msg->send.nm_m;
809 	int error = 0;
810 	struct inpcb *inp;
811 	struct tcpcb *tp;
812 	TCPDEBUG0;
813 
814 	KKASSERT(msg->send.nm_control == NULL);
815 	KKASSERT(msg->send.nm_addr == NULL);
816 	KKASSERT((flags & PRUS_FREEADDR) == 0);
817 
818 	inp = so->so_pcb;
819 
820 	if (inp == NULL) {
821 		/*
822 		 * OOPS! we lost a race, the TCP session got reset after
823 		 * we checked SS_CANTSENDMORE, eg: while doing uiomove or a
824 		 * network interrupt in the non-critical section of sosend().
825 		 */
826 		m_freem(m);
827 		error = ECONNRESET;	/* XXX EPIPE? */
828 		tp = NULL;
829 		TCPDEBUG1();
830 		goto out;
831 	}
832 	tp = intotcpcb(inp);
833 	TCPDEBUG1();
834 
835 #ifdef foo
836 	/*
837 	 * This is no longer necessary, since:
838 	 * - sosendtcp() has already checked it for us
839 	 * - It does not work with asynchronized send
840 	 */
841 
842 	/*
843 	 * Don't let too much OOB data build up
844 	 */
845 	if (flags & PRUS_OOB) {
846 		if (ssb_space(&so->so_snd) < -512) {
847 			m_freem(m);
848 			error = ENOBUFS;
849 			goto out;
850 		}
851 	}
852 #endif
853 
854 	/*
855 	 * Pump the data into the socket.
856 	 */
857 	if (m) {
858 		ssb_appendstream(&so->so_snd, m);
859 		sowwakeup(so);
860 	}
861 	if (flags & PRUS_OOB) {
862 		/*
863 		 * According to RFC961 (Assigned Protocols),
864 		 * the urgent pointer points to the last octet
865 		 * of urgent data.  We continue, however,
866 		 * to consider it to indicate the first octet
867 		 * of data past the urgent section.
868 		 * Otherwise, snd_up should be one lower.
869 		 */
870 		tp->snd_up = tp->snd_una + so->so_snd.ssb_cc;
871 		tp->t_flags |= TF_FORCE;
872 		error = tcp_output(tp);
873 		tp->t_flags &= ~TF_FORCE;
874 	} else {
875 		if (flags & PRUS_EOF) {
876 			/*
877 			 * Close the send side of the connection after
878 			 * the data is sent.
879 			 */
880 			socantsendmore(so);
881 			tp = tcp_usrclosed(tp);
882 		}
883 		if (tp != NULL && !tcp_output_pending(tp)) {
884 			if (flags & PRUS_MORETOCOME)
885 				tp->t_flags |= TF_MORETOCOME;
886 			error = tcp_output_fair(tp);
887 			if (flags & PRUS_MORETOCOME)
888 				tp->t_flags &= ~TF_MORETOCOME;
889 		}
890 	}
891 	COMMON_END1((flags & PRUS_OOB) ? PRU_SENDOOB :
892 		   ((flags & PRUS_EOF) ? PRU_SEND_EOF : PRU_SEND),
893 		   (flags & PRUS_NOREPLY));
894 }
895 
896 /*
897  * NOTE: (so) is referenced from soabort*() and netmsg_pru_abort()
898  *	 will sofree() it when we return.
899  */
900 static void
901 tcp_usr_abort(netmsg_t msg)
902 {
903 	struct socket *so = msg->abort.base.nm_so;
904 	int error = 0;
905 	struct inpcb *inp;
906 	struct tcpcb *tp;
907 
908 	COMMON_START(so, inp, 1);
909 	tp = tcp_drop(tp, ECONNABORTED);
910 	COMMON_END(PRU_ABORT);
911 }
912 
913 /*
914  * Receive out-of-band data.
915  */
916 static void
917 tcp_usr_rcvoob(netmsg_t msg)
918 {
919 	struct socket *so = msg->rcvoob.base.nm_so;
920 	struct mbuf *m = msg->rcvoob.nm_m;
921 	int flags = msg->rcvoob.nm_flags;
922 	int error = 0;
923 	struct inpcb *inp;
924 	struct tcpcb *tp;
925 
926 	COMMON_START(so, inp, 0);
927 	if ((so->so_oobmark == 0 &&
928 	     (so->so_state & SS_RCVATMARK) == 0) ||
929 	    so->so_options & SO_OOBINLINE ||
930 	    tp->t_oobflags & TCPOOB_HADDATA) {
931 		error = EINVAL;
932 		goto out;
933 	}
934 	if ((tp->t_oobflags & TCPOOB_HAVEDATA) == 0) {
935 		error = EWOULDBLOCK;
936 		goto out;
937 	}
938 	m->m_len = 1;
939 	*mtod(m, caddr_t) = tp->t_iobc;
940 	if ((flags & MSG_PEEK) == 0)
941 		tp->t_oobflags ^= (TCPOOB_HAVEDATA | TCPOOB_HADDATA);
942 	COMMON_END(PRU_RCVOOB);
943 }
944 
945 static void
946 tcp_usr_savefaddr(struct socket *so, const struct sockaddr *faddr)
947 {
948 	in_savefaddr(so, faddr);
949 }
950 
951 #ifdef INET6
952 static void
953 tcp6_usr_savefaddr(struct socket *so, const struct sockaddr *faddr)
954 {
955 	in6_savefaddr(so, faddr);
956 }
957 #endif
958 
959 static int
960 tcp_usr_preconnect(struct socket *so, const struct sockaddr *nam,
961     struct thread *td __unused)
962 {
963 	const struct sockaddr_in *sinp;
964 
965 	sinp = (const struct sockaddr_in *)nam;
966 	if (sinp->sin_family == AF_INET &&
967 	    IN_MULTICAST(ntohl(sinp->sin_addr.s_addr)))
968 		return EAFNOSUPPORT;
969 
970 	soisconnecting(so);
971 	return 0;
972 }
973 
974 /* xxx - should be const */
975 struct pr_usrreqs tcp_usrreqs = {
976 	.pru_abort = tcp_usr_abort,
977 	.pru_accept = tcp_usr_accept,
978 	.pru_attach = tcp_usr_attach,
979 	.pru_bind = tcp_usr_bind,
980 	.pru_connect = tcp_usr_connect,
981 	.pru_connect2 = pr_generic_notsupp,
982 	.pru_control = in_control_dispatch,
983 	.pru_detach = tcp_usr_detach,
984 	.pru_disconnect = tcp_usr_disconnect,
985 	.pru_listen = tcp_usr_listen,
986 	.pru_peeraddr = in_setpeeraddr_dispatch,
987 	.pru_rcvd = tcp_usr_rcvd,
988 	.pru_rcvoob = tcp_usr_rcvoob,
989 	.pru_send = tcp_usr_send,
990 	.pru_sense = pru_sense_null,
991 	.pru_shutdown = tcp_usr_shutdown,
992 	.pru_sockaddr = in_setsockaddr_dispatch,
993 	.pru_sosend = sosendtcp,
994 	.pru_soreceive = sorecvtcp,
995 	.pru_savefaddr = tcp_usr_savefaddr,
996 	.pru_preconnect = tcp_usr_preconnect,
997 	.pru_preattach = tcp_usr_preattach
998 };
999 
1000 #ifdef INET6
1001 struct pr_usrreqs tcp6_usrreqs = {
1002 	.pru_abort = tcp_usr_abort,
1003 	.pru_accept = tcp6_usr_accept,
1004 	.pru_attach = tcp_usr_attach,
1005 	.pru_bind = tcp6_usr_bind,
1006 	.pru_connect = tcp6_usr_connect,
1007 	.pru_connect2 = pr_generic_notsupp,
1008 	.pru_control = in6_control_dispatch,
1009 	.pru_detach = tcp_usr_detach,
1010 	.pru_disconnect = tcp_usr_disconnect,
1011 	.pru_listen = tcp6_usr_listen,
1012 	.pru_peeraddr = in6_setpeeraddr_dispatch,
1013 	.pru_rcvd = tcp_usr_rcvd,
1014 	.pru_rcvoob = tcp_usr_rcvoob,
1015 	.pru_send = tcp_usr_send,
1016 	.pru_sense = pru_sense_null,
1017 	.pru_shutdown = tcp_usr_shutdown,
1018 	.pru_sockaddr = in6_setsockaddr_dispatch,
1019 	.pru_sosend = sosendtcp,
1020 	.pru_soreceive = sorecvtcp,
1021 	.pru_savefaddr = tcp6_usr_savefaddr
1022 };
1023 #endif /* INET6 */
1024 
1025 static int
1026 tcp_connect_oncpu(struct tcpcb *tp, int flags, struct mbuf *m,
1027 		  const struct sockaddr_in *sin, struct sockaddr_in *if_sin,
1028 		  uint16_t hash)
1029 {
1030 	struct inpcb *inp = tp->t_inpcb, *oinp;
1031 	struct socket *so = inp->inp_socket;
1032 	struct route *ro = &inp->inp_route;
1033 
1034 	KASSERT(inp->inp_pcbinfo == &tcbinfo[mycpu->gd_cpuid],
1035 	    ("pcbinfo mismatch"));
1036 
1037 	oinp = in_pcblookup_hash(inp->inp_pcbinfo,
1038 				 sin->sin_addr, sin->sin_port,
1039 				 (inp->inp_laddr.s_addr != INADDR_ANY ?
1040 				  inp->inp_laddr : if_sin->sin_addr),
1041 				inp->inp_lport, 0, NULL);
1042 	if (oinp != NULL) {
1043 		m_freem(m);
1044 		return (EADDRINUSE);
1045 	}
1046 	if (inp->inp_laddr.s_addr == INADDR_ANY)
1047 		inp->inp_laddr = if_sin->sin_addr;
1048 	KASSERT(inp->inp_faddr.s_addr == sin->sin_addr.s_addr,
1049 	    ("faddr mismatch for reconnect"));
1050 	KASSERT(inp->inp_fport == sin->sin_port,
1051 	    ("fport mismatch for reconnect"));
1052 	in_pcbinsconnhash(inp);
1053 
1054 	inp->inp_flags |= INP_HASH;
1055 	inp->inp_hashval = hash;
1056 
1057 	/*
1058 	 * We are now on the inpcb's owner CPU, if the cached route was
1059 	 * freed because the rtentry's owner CPU is not the current CPU
1060 	 * (e.g. in tcp_connect()), then we try to reallocate it here with
1061 	 * the hope that a rtentry may be cloned from a RTF_PRCLONING
1062 	 * rtentry.
1063 	 */
1064 	if (!(inp->inp_socket->so_options & SO_DONTROUTE) && /*XXX*/
1065 	    ro->ro_rt == NULL) {
1066 		bzero(&ro->ro_dst, sizeof(struct sockaddr_in));
1067 		ro->ro_dst.sa_family = AF_INET;
1068 		ro->ro_dst.sa_len = sizeof(struct sockaddr_in);
1069 		((struct sockaddr_in *)&ro->ro_dst)->sin_addr =
1070 			sin->sin_addr;
1071 		rtalloc(ro);
1072 	}
1073 
1074 	/*
1075 	 * Now that no more errors can occur, change the protocol processing
1076 	 * port to the current thread (which is the correct thread).
1077 	 *
1078 	 * Create TCP timer message now; we are on the tcpcb's owner
1079 	 * CPU/thread.
1080 	 */
1081 	tcp_create_timermsg(tp, &curthread->td_msgport);
1082 
1083 	/*
1084 	 * Compute window scaling to request.  Use a larger scaling then
1085 	 * needed for the initial receive buffer in case the receive buffer
1086 	 * gets expanded.
1087 	 */
1088 	if (tp->request_r_scale < TCP_MIN_WINSHIFT)
1089 		tp->request_r_scale = TCP_MIN_WINSHIFT;
1090 	while (tp->request_r_scale < TCP_MAX_WINSHIFT &&
1091 	       (TCP_MAXWIN << tp->request_r_scale) < so->so_rcv.ssb_hiwat
1092 	) {
1093 		tp->request_r_scale++;
1094 	}
1095 
1096 	soisconnecting(so);
1097 	tcpstat.tcps_connattempt++;
1098 	TCP_STATE_CHANGE(tp, TCPS_SYN_SENT);
1099 	tcp_callout_reset(tp, tp->tt_keep, tp->t_keepinit, tcp_timer_keep);
1100 	tp->iss = tcp_new_isn(tp);
1101 	tcp_sendseqinit(tp);
1102 	if (m) {
1103 		ssb_appendstream(&so->so_snd, m);
1104 		m = NULL;
1105 		if (flags & PRUS_OOB)
1106 			tp->snd_up = tp->snd_una + so->so_snd.ssb_cc;
1107 	}
1108 
1109 	/*
1110 	 * Close the send side of the connection after
1111 	 * the data is sent if flagged.
1112 	 */
1113 	if ((flags & (PRUS_OOB|PRUS_EOF)) == PRUS_EOF) {
1114 		socantsendmore(so);
1115 		tp = tcp_usrclosed(tp);
1116 	}
1117 	return (tcp_output(tp));
1118 }
1119 
1120 /*
1121  * Common subroutine to open a TCP connection to remote host specified
1122  * by struct sockaddr_in in mbuf *nam.  Call in_pcbbind to assign a local
1123  * port number if needed.  Call in_pcbladdr to do the routing and to choose
1124  * a local host address (interface).
1125  * Initialize connection parameters and enter SYN-SENT state.
1126  */
1127 static void
1128 tcp_connect(netmsg_t msg)
1129 {
1130 	struct socket *so = msg->connect.base.nm_so;
1131 	struct sockaddr *nam = msg->connect.nm_nam;
1132 	struct thread *td = msg->connect.nm_td;
1133 	struct sockaddr_in *sin = (struct sockaddr_in *)nam;
1134 	struct sockaddr_in *if_sin = NULL;
1135 	struct inpcb *inp;
1136 	struct tcpcb *tp;
1137 	int error;
1138 	uint16_t hash;
1139 	lwkt_port_t port;
1140 
1141 	COMMON_START(so, inp, 0);
1142 
1143 	/*
1144 	 * Reconnect our pcb if we have to
1145 	 */
1146 	if (msg->connect.nm_flags & PRUC_RECONNECT) {
1147 		msg->connect.nm_flags &= ~PRUC_RECONNECT;
1148 		TCP_STATE_MIGRATE_END(tp);
1149 		in_pcblink(so->so_pcb, &tcbinfo[mycpu->gd_cpuid]);
1150 	} else {
1151 		if (inp->inp_faddr.s_addr != INADDR_ANY) {
1152 			error = EISCONN;
1153 			if (so->so_state & SS_ISCONNECTING)
1154 				error = EALREADY;
1155 			goto out;
1156 		}
1157 		KASSERT(inp->inp_fport == 0, ("invalid fport"));
1158 	}
1159 
1160 	/*
1161 	 * Select local port, if it is not yet selected.
1162 	 */
1163 	if (inp->inp_lport == 0) {
1164 		KKASSERT(inp->inp_laddr.s_addr == INADDR_ANY);
1165 
1166 		error = in_pcbladdr(inp, nam, &if_sin, td);
1167 		if (error)
1168 			goto out;
1169 		inp->inp_laddr.s_addr = if_sin->sin_addr.s_addr;
1170 		msg->connect.nm_flags |= PRUC_HASLADDR;
1171 
1172 		/*
1173 		 * Install faddr/fport earlier, so that when this
1174 		 * inpcb is installed on to the lport hash, the
1175 		 * 4-tuple contains correct value.
1176 		 *
1177 		 * NOTE: The faddr/fport will have to be installed
1178 		 * after the in_pcbladdr(), which may change them.
1179 		 */
1180 		inp->inp_faddr = sin->sin_addr;
1181 		inp->inp_fport = sin->sin_port;
1182 
1183 		error = in_pcbbind_remote(inp, nam, td);
1184 		if (error)
1185 			goto out;
1186 	}
1187 
1188 	if ((msg->connect.nm_flags & PRUC_HASLADDR) == 0) {
1189 		/*
1190 		 * Rarely used path:
1191 		 * This inpcb was bound before this connect.
1192 		 */
1193 		error = in_pcbladdr(inp, nam, &if_sin, td);
1194 		if (error)
1195 			goto out;
1196 
1197 		/*
1198 		 * Save or refresh the faddr/fport, since they may
1199 		 * be changed by in_pcbladdr().
1200 		 */
1201 		inp->inp_faddr = sin->sin_addr;
1202 		inp->inp_fport = sin->sin_port;
1203 	}
1204 #ifdef INVARIANTS
1205 	else {
1206 		KASSERT(inp->inp_faddr.s_addr == sin->sin_addr.s_addr,
1207 		    ("faddr mismatch for reconnect"));
1208 		KASSERT(inp->inp_fport == sin->sin_port,
1209 		    ("fport mismatch for reconnect"));
1210 	}
1211 #endif
1212 	KKASSERT(inp->inp_socket == so);
1213 
1214 	hash = tcp_addrhash(sin->sin_addr.s_addr, sin->sin_port,
1215 			    (inp->inp_laddr.s_addr != INADDR_ANY ?
1216 			     inp->inp_laddr.s_addr : if_sin->sin_addr.s_addr),
1217 			    inp->inp_lport);
1218 	port = netisr_hashport(hash);
1219 
1220 	if (port != &curthread->td_msgport) {
1221 		lwkt_msg_t lmsg = &msg->connect.base.lmsg;
1222 
1223 		/*
1224 		 * in_pcbladdr() may have allocated a route entry for us
1225 		 * on the current CPU, but we need a route entry on the
1226 		 * inpcb's owner CPU, so free it here.
1227 		 */
1228 		in_pcbresetroute(inp);
1229 
1230 		/*
1231 		 * We are moving the protocol processing port the socket
1232 		 * is on, we have to unlink here and re-link on the
1233 		 * target cpu.
1234 		 */
1235 		in_pcbunlink(so->so_pcb, &tcbinfo[mycpu->gd_cpuid]);
1236 		msg->connect.nm_flags |= PRUC_RECONNECT;
1237 		msg->connect.base.nm_dispatch = tcp_connect;
1238 
1239 		TCP_STATE_MIGRATE_START(tp);
1240 
1241 		/*
1242 		 * Use message put done receipt to change this socket's
1243 		 * so_port, i.e. _after_ this message was put onto the
1244 		 * target netisr's msgport but _before_ the message could
1245 		 * be pulled from the target netisr's msgport, so that:
1246 		 * - The upper half (socket code) will not see the new
1247 		 *   msgport before this message reaches the new msgport
1248 		 *   and messages for this socket will be ordered.
1249 		 * - This message will see the new msgport, when its
1250 		 *   handler is called in the target netisr.
1251 		 *
1252 		 * NOTE:
1253 		 * We MUST use messege put done receipt to change this
1254 		 * socket's so_port:
1255 		 * If we changed the so_port in this netisr after the
1256 		 * lwkt_forwardmsg (so messages for this socket will be
1257 		 * ordered) and changed the so_port in the target netisr
1258 		 * at the very beginning of this message's handler, we
1259 		 * would suffer so_port overwritten race, given this
1260 		 * message might be forwarded again.
1261 		 *
1262 		 * NOTE:
1263 		 * This mechanism depends on that the netisr's msgport
1264 		 * is spin msgport (currently it is :).
1265 		 *
1266 		 * If the upper half saw the new msgport before this
1267 		 * message reached the target netisr's msgport, the
1268 		 * messages sent from the upper half could reach the new
1269 		 * msgport before this message, thus there would be
1270 		 * message reordering.  The worst case could be soclose()
1271 		 * saw the new msgport and the detach message could reach
1272 		 * the new msgport before this message, i.e. the inpcb
1273 		 * could have been destroyed when this message was still
1274 		 * pending on or on its way to the new msgport.  Other
1275 		 * weird cases could also happen, e.g. inpcb->inp_pcbinfo,
1276 		 * since we have unlinked this inpcb from the current
1277 		 * pcbinfo first.
1278 		 */
1279 		lwkt_setmsg_receipt(lmsg, tcp_sosetport);
1280 		lwkt_forwardmsg(port, lmsg);
1281 		/* msg invalid now */
1282 		return;
1283 	} else if (msg->connect.nm_flags & PRUC_HELDTD) {
1284 		/*
1285 		 * The original thread is no longer needed; release it.
1286 		 */
1287 		lwkt_rele(td);
1288 		msg->connect.nm_flags &= ~PRUC_HELDTD;
1289 	}
1290 	error = tcp_connect_oncpu(tp, msg->connect.nm_sndflags,
1291 				  msg->connect.nm_m, sin, if_sin, hash);
1292 	msg->connect.nm_m = NULL;
1293 out:
1294 	if (msg->connect.nm_m) {
1295 		m_freem(msg->connect.nm_m);
1296 		msg->connect.nm_m = NULL;
1297 	}
1298 	if (msg->connect.nm_flags & PRUC_HELDTD)
1299 		lwkt_rele(td);
1300 	if (error && (msg->connect.nm_flags & PRUC_ASYNC)) {
1301 		so->so_error = error;
1302 		soisdisconnected(so);
1303 	}
1304 	lwkt_replymsg(&msg->connect.base.lmsg, error);
1305 	/* msg invalid now */
1306 }
1307 
1308 #ifdef INET6
1309 
1310 static void
1311 tcp6_connect(netmsg_t msg)
1312 {
1313 	struct tcpcb *tp;
1314 	struct socket *so = msg->connect.base.nm_so;
1315 	struct sockaddr *nam = msg->connect.nm_nam;
1316 	struct thread *td = msg->connect.nm_td;
1317 	struct inpcb *inp;
1318 	struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)nam;
1319 	struct in6_addr *addr6;
1320 	lwkt_port_t port;
1321 	int error;
1322 
1323 	COMMON_START(so, inp, 0);
1324 
1325 	/*
1326 	 * Reconnect our pcb if we have to
1327 	 */
1328 	if (msg->connect.nm_flags & PRUC_RECONNECT) {
1329 		msg->connect.nm_flags &= ~PRUC_RECONNECT;
1330 		TCP_STATE_MIGRATE_END(tp);
1331 		in_pcblink(so->so_pcb, &tcbinfo[mycpu->gd_cpuid]);
1332 	}
1333 
1334 	/*
1335 	 * Bind if we have to
1336 	 */
1337 	if (inp->inp_lport == 0) {
1338 		error = in6_pcbbind(inp, NULL, td);
1339 		if (error)
1340 			goto out;
1341 	}
1342 
1343 	/*
1344 	 * Cannot simply call in_pcbconnect, because there might be an
1345 	 * earlier incarnation of this same connection still in
1346 	 * TIME_WAIT state, creating an ADDRINUSE error.
1347 	 */
1348 	error = in6_pcbladdr(inp, nam, &addr6, td);
1349 	if (error)
1350 		goto out;
1351 
1352 	port = tcp6_addrport();	/* XXX hack for now, always cpu0 */
1353 
1354 	if (port != &curthread->td_msgport) {
1355 		lwkt_msg_t lmsg = &msg->connect.base.lmsg;
1356 
1357 		/*
1358 		 * in_pcbladdr() may have allocated a route entry for us
1359 		 * on the current CPU, but we need a route entry on the
1360 		 * inpcb's owner CPU, so free it here.
1361 		 */
1362 		in_pcbresetroute(inp);
1363 
1364 		in_pcbunlink(so->so_pcb, &tcbinfo[mycpu->gd_cpuid]);
1365 		msg->connect.nm_flags |= PRUC_RECONNECT;
1366 		msg->connect.base.nm_dispatch = tcp6_connect;
1367 
1368 		TCP_STATE_MIGRATE_START(tp);
1369 
1370 		/* See the related comment in tcp_connect() */
1371 		lwkt_setmsg_receipt(lmsg, tcp_sosetport);
1372 		lwkt_forwardmsg(port, lmsg);
1373 		/* msg invalid now */
1374 		return;
1375 	}
1376 	error = tcp6_connect_oncpu(tp, msg->connect.nm_sndflags,
1377 				   &msg->connect.nm_m, sin6, addr6);
1378 	/* nm_m may still be intact */
1379 out:
1380 	if (msg->connect.nm_m) {
1381 		m_freem(msg->connect.nm_m);
1382 		msg->connect.nm_m = NULL;
1383 	}
1384 	lwkt_replymsg(&msg->connect.base.lmsg, error);
1385 	/* msg invalid now */
1386 }
1387 
1388 static int
1389 tcp6_connect_oncpu(struct tcpcb *tp, int flags, struct mbuf **mp,
1390 		   struct sockaddr_in6 *sin6, struct in6_addr *addr6)
1391 {
1392 	struct mbuf *m = *mp;
1393 	struct inpcb *inp = tp->t_inpcb;
1394 	struct socket *so = inp->inp_socket;
1395 	struct inpcb *oinp;
1396 
1397 	/*
1398 	 * Cannot simply call in_pcbconnect, because there might be an
1399 	 * earlier incarnation of this same connection still in
1400 	 * TIME_WAIT state, creating an ADDRINUSE error.
1401 	 */
1402 	oinp = in6_pcblookup_hash(inp->inp_pcbinfo,
1403 				  &sin6->sin6_addr, sin6->sin6_port,
1404 				  (IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr) ?
1405 				      addr6 : &inp->in6p_laddr),
1406 				  inp->inp_lport,  0, NULL);
1407 	if (oinp)
1408 		return (EADDRINUSE);
1409 
1410 	if (IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr))
1411 		inp->in6p_laddr = *addr6;
1412 	inp->in6p_faddr = sin6->sin6_addr;
1413 	inp->inp_fport = sin6->sin6_port;
1414 	if ((sin6->sin6_flowinfo & IPV6_FLOWINFO_MASK) != 0)
1415 		inp->in6p_flowinfo = sin6->sin6_flowinfo;
1416 	in_pcbinsconnhash(inp);
1417 
1418 	/*
1419 	 * Now that no more errors can occur, change the protocol processing
1420 	 * port to the current thread (which is the correct thread).
1421 	 *
1422 	 * Create TCP timer message now; we are on the tcpcb's owner
1423 	 * CPU/thread.
1424 	 */
1425 	tcp_create_timermsg(tp, &curthread->td_msgport);
1426 
1427 	/* Compute window scaling to request.  */
1428 	if (tp->request_r_scale < TCP_MIN_WINSHIFT)
1429 		tp->request_r_scale = TCP_MIN_WINSHIFT;
1430 	while (tp->request_r_scale < TCP_MAX_WINSHIFT &&
1431 	    (TCP_MAXWIN << tp->request_r_scale) < so->so_rcv.ssb_hiwat) {
1432 		tp->request_r_scale++;
1433 	}
1434 
1435 	soisconnecting(so);
1436 	tcpstat.tcps_connattempt++;
1437 	TCP_STATE_CHANGE(tp, TCPS_SYN_SENT);
1438 	tcp_callout_reset(tp, tp->tt_keep, tp->t_keepinit, tcp_timer_keep);
1439 	tp->iss = tcp_new_isn(tp);
1440 	tcp_sendseqinit(tp);
1441 	if (m) {
1442 		ssb_appendstream(&so->so_snd, m);
1443 		*mp = NULL;
1444 		if (flags & PRUS_OOB)
1445 			tp->snd_up = tp->snd_una + so->so_snd.ssb_cc;
1446 	}
1447 
1448 	/*
1449 	 * Close the send side of the connection after
1450 	 * the data is sent if flagged.
1451 	 */
1452 	if ((flags & (PRUS_OOB|PRUS_EOF)) == PRUS_EOF) {
1453 		socantsendmore(so);
1454 		tp = tcp_usrclosed(tp);
1455 	}
1456 	return (tcp_output(tp));
1457 }
1458 
1459 #endif /* INET6 */
1460 
1461 /*
1462  * The new sockopt interface makes it possible for us to block in the
1463  * copyin/out step (if we take a page fault).  Taking a page fault while
1464  * in a critical section is probably a Bad Thing.  (Since sockets and pcbs
1465  * both now use TSM, there probably isn't any need for this function to
1466  * run in a critical section any more.  This needs more examination.)
1467  */
1468 void
1469 tcp_ctloutput(netmsg_t msg)
1470 {
1471 	struct socket *so = msg->base.nm_so;
1472 	struct sockopt *sopt = msg->ctloutput.nm_sopt;
1473 	struct thread *td = NULL;
1474 	int	error, opt, optval, opthz;
1475 	struct	inpcb *inp;
1476 	struct	tcpcb *tp;
1477 
1478 	if (msg->ctloutput.nm_flags & PRCO_HELDTD)
1479 		td = sopt->sopt_td;
1480 
1481 	error = 0;
1482 	inp = so->so_pcb;
1483 	if (inp == NULL) {
1484 		error = ECONNRESET;
1485 		goto done;
1486 	}
1487 	tp = intotcpcb(inp);
1488 
1489 	/* Get socket's owner cpuid hint */
1490 	if (sopt->sopt_level == SOL_SOCKET &&
1491 	    sopt->sopt_dir == SOPT_GET &&
1492 	    sopt->sopt_name == SO_CPUHINT) {
1493 		if (tp->t_flags & TF_LISTEN) {
1494 			/*
1495 			 * Listen sockets owner cpuid is always 0,
1496 			 * which does not make sense if SO_REUSEPORT
1497 			 * is not set.
1498 			 *
1499 			 * NOTE: inp_lgrpindex is _not_ assigned in jail.
1500 			 */
1501 			if ((so->so_options & SO_REUSEPORT) &&
1502 			    inp->inp_lgrpindex >= 0)
1503 				optval = inp->inp_lgrpindex % netisr_ncpus;
1504 			else
1505 				optval = -1; /* no hint */
1506 		} else {
1507 			optval = mycpuid;
1508 		}
1509 		soopt_from_kbuf(sopt, &optval, sizeof(optval));
1510 		goto done;
1511 	}
1512 
1513 	if (sopt->sopt_level != IPPROTO_TCP) {
1514 		if (sopt->sopt_level == IPPROTO_IP) {
1515 			switch (sopt->sopt_name) {
1516 			case IP_MULTICAST_IF:
1517 			case IP_MULTICAST_VIF:
1518 			case IP_MULTICAST_TTL:
1519 			case IP_MULTICAST_LOOP:
1520 			case IP_ADD_MEMBERSHIP:
1521 			case IP_DROP_MEMBERSHIP:
1522 				/*
1523 				 * Multicast does not make sense on
1524 				 * TCP sockets.
1525 				 */
1526 				error = EOPNOTSUPP;
1527 				goto done;
1528 			}
1529 		}
1530 #ifdef INET6
1531 		if (INP_CHECK_SOCKAF(so, AF_INET6))
1532 			ip6_ctloutput_dispatch(msg);
1533 		else
1534 #endif /* INET6 */
1535 		ip_ctloutput(msg);
1536 		/* msg invalid now */
1537 		if (td != NULL)
1538 			lwkt_rele(td);
1539 		return;
1540 	}
1541 
1542 	switch (sopt->sopt_dir) {
1543 	case SOPT_SET:
1544 		error = soopt_to_kbuf(sopt, &optval, sizeof optval,
1545 				      sizeof optval);
1546 		if (error)
1547 			break;
1548 		switch (sopt->sopt_name) {
1549 		case TCP_FASTKEEP:
1550 			if (optval > 0)
1551 				tp->t_keepidle = tp->t_keepintvl;
1552 			else
1553 				tp->t_keepidle = tcp_keepidle;
1554 			tcp_timer_keep_activity(tp, 0);
1555 			break;
1556 #ifdef TCP_SIGNATURE
1557 		case TCP_SIGNATURE_ENABLE:
1558 			if (tp->t_state == TCPS_CLOSED) {
1559 				/*
1560 				 * This is the only safe state that this
1561 				 * option could be changed.  Some segments
1562 				 * could already have been sent in other
1563 				 * states.
1564 				 */
1565 				if (optval > 0)
1566 					tp->t_flags |= TF_SIGNATURE;
1567 				else
1568 					tp->t_flags &= ~TF_SIGNATURE;
1569 			} else {
1570 				error = EOPNOTSUPP;
1571 			}
1572 			break;
1573 #endif /* TCP_SIGNATURE */
1574 		case TCP_NODELAY:
1575 		case TCP_NOOPT:
1576 			switch (sopt->sopt_name) {
1577 			case TCP_NODELAY:
1578 				opt = TF_NODELAY;
1579 				break;
1580 			case TCP_NOOPT:
1581 				opt = TF_NOOPT;
1582 				break;
1583 			default:
1584 				opt = 0; /* dead code to fool gcc */
1585 				break;
1586 			}
1587 
1588 			if (optval)
1589 				tp->t_flags |= opt;
1590 			else
1591 				tp->t_flags &= ~opt;
1592 			break;
1593 
1594 		case TCP_NOPUSH:
1595 			if (tcp_disable_nopush)
1596 				break;
1597 			if (optval)
1598 				tp->t_flags |= TF_NOPUSH;
1599 			else {
1600 				tp->t_flags &= ~TF_NOPUSH;
1601 				error = tcp_output(tp);
1602 			}
1603 			break;
1604 
1605 		case TCP_MAXSEG:
1606 			/*
1607 			 * Must be between 0 and maxseg.  If the requested
1608 			 * maxseg is too small to satisfy the desired minmss,
1609 			 * pump it up (silently so sysctl modifications of
1610 			 * minmss do not create unexpected program failures).
1611 			 * Handle degenerate cases.
1612 			 */
1613 			if (optval > 0 && optval <= tp->t_maxseg) {
1614 				if (optval + 40 < tcp_minmss) {
1615 					optval = tcp_minmss - 40;
1616 					if (optval < 0)
1617 						optval = 1;
1618 				}
1619 				tp->t_maxseg = optval;
1620 			} else {
1621 				error = EINVAL;
1622 			}
1623 			break;
1624 
1625 		case TCP_KEEPINIT:
1626 		case TCP_KEEPIDLE:
1627 		case TCP_KEEPINTVL:
1628 			if (optval < 1 || optval > MAXKEEPALIVE) {
1629 				error = EINVAL;
1630 				break;
1631 			}
1632 			opthz = optval * hz;
1633 
1634 			switch (sopt->sopt_name) {
1635 			case TCP_KEEPINIT:
1636 				tp->t_keepinit = opthz;
1637 				break;
1638 			case TCP_KEEPIDLE:
1639 				tp->t_keepidle = opthz;
1640 				tcp_timer_keep_activity(tp, 0);
1641 				break;
1642 			case TCP_KEEPINTVL:
1643 				tp->t_keepintvl = opthz;
1644 				tp->t_maxidle = tp->t_keepintvl * tp->t_keepcnt;
1645 				break;
1646 			}
1647 			break;
1648 
1649 		case TCP_KEEPCNT:
1650 			if (optval < 1 || optval > MAXKEEPCNT) {
1651 				error = EINVAL;
1652 				break;
1653 			}
1654 			tp->t_keepcnt = optval;
1655 			tp->t_maxidle = tp->t_keepintvl * tp->t_keepcnt;
1656 			break;
1657 
1658 		default:
1659 			error = ENOPROTOOPT;
1660 			break;
1661 		}
1662 		break;
1663 
1664 	case SOPT_GET:
1665 		switch (sopt->sopt_name) {
1666 #ifdef TCP_SIGNATURE
1667 		case TCP_SIGNATURE_ENABLE:
1668 			optval = (tp->t_flags & TF_SIGNATURE) ? 1 : 0;
1669 			break;
1670 #endif /* TCP_SIGNATURE */
1671 		case TCP_NODELAY:
1672 			optval = tp->t_flags & TF_NODELAY;
1673 			break;
1674 		case TCP_MAXSEG:
1675 			optval = tp->t_maxseg;
1676 			break;
1677 		case TCP_NOOPT:
1678 			optval = tp->t_flags & TF_NOOPT;
1679 			break;
1680 		case TCP_NOPUSH:
1681 			optval = tp->t_flags & TF_NOPUSH;
1682 			break;
1683 		case TCP_KEEPINIT:
1684 			optval = tp->t_keepinit / hz;
1685 			break;
1686 		case TCP_KEEPIDLE:
1687 			optval = tp->t_keepidle / hz;
1688 			break;
1689 		case TCP_KEEPINTVL:
1690 			optval = tp->t_keepintvl / hz;
1691 			break;
1692 		case TCP_KEEPCNT:
1693 			optval = tp->t_keepcnt;
1694 			break;
1695 		default:
1696 			error = ENOPROTOOPT;
1697 			break;
1698 		}
1699 		if (error == 0)
1700 			soopt_from_kbuf(sopt, &optval, sizeof optval);
1701 		break;
1702 	}
1703 done:
1704 	if (td != NULL)
1705 		lwkt_rele(td);
1706 	lwkt_replymsg(&msg->lmsg, error);
1707 }
1708 
1709 struct netmsg_tcp_ctloutput {
1710 	struct netmsg_pr_ctloutput ctloutput;
1711 	struct sockopt		sopt;
1712 	int			sopt_val;
1713 };
1714 
1715 /*
1716  * Allocate netmsg_pr_ctloutput for asynchronous tcp_ctloutput.
1717  */
1718 struct netmsg_pr_ctloutput *
1719 tcp_ctloutmsg(struct sockopt *sopt)
1720 {
1721 	struct netmsg_tcp_ctloutput *msg;
1722 	int flags = 0, error;
1723 
1724 	KASSERT(sopt->sopt_dir == SOPT_SET, ("not from ctloutput"));
1725 
1726 	/* Only small set of options allows asynchronous setting. */
1727 	if (sopt->sopt_level != IPPROTO_TCP)
1728 		return NULL;
1729 	switch (sopt->sopt_name) {
1730 	case TCP_NODELAY:
1731 	case TCP_NOOPT:
1732 	case TCP_NOPUSH:
1733 	case TCP_FASTKEEP:
1734 		break;
1735 	default:
1736 		return NULL;
1737 	}
1738 
1739 	msg = kmalloc(sizeof(*msg), M_LWKTMSG, M_WAITOK | M_NULLOK);
1740 	if (msg == NULL) {
1741 		/* Fallback to synchronous tcp_ctloutput */
1742 		return NULL;
1743 	}
1744 
1745 	/* Save the sockopt */
1746 	msg->sopt = *sopt;
1747 
1748 	/* Fixup the sopt.sopt_val ptr */
1749 	error = sooptcopyin(sopt, &msg->sopt_val,
1750 	    sizeof(msg->sopt_val), sizeof(msg->sopt_val));
1751 	if (error) {
1752 		kfree(msg, M_LWKTMSG);
1753 		return NULL;
1754 	}
1755 	msg->sopt.sopt_val = &msg->sopt_val;
1756 
1757 	/* Hold the current thread */
1758 	if (msg->sopt.sopt_td != NULL) {
1759 		flags |= PRCO_HELDTD;
1760 		lwkt_hold(msg->sopt.sopt_td);
1761 	}
1762 
1763 	msg->ctloutput.nm_flags = flags;
1764 	msg->ctloutput.nm_sopt = &msg->sopt;
1765 
1766 	return &msg->ctloutput;
1767 }
1768 
1769 /*
1770  * tcp_sendspace and tcp_recvspace are the default send and receive window
1771  * sizes, respectively.  These are obsolescent (this information should
1772  * be set by the route).
1773  *
1774  * Use a default that does not require tcp window scaling to be turned
1775  * on.  Individual programs or the administrator can increase the default.
1776  */
1777 u_long	tcp_sendspace = 57344;	/* largest multiple of PAGE_SIZE < 64k */
1778 SYSCTL_INT(_net_inet_tcp, TCPCTL_SENDSPACE, sendspace, CTLFLAG_RW,
1779     &tcp_sendspace , 0, "Maximum outgoing TCP datagram size");
1780 u_long	tcp_recvspace = 57344;	/* largest multiple of PAGE_SIZE < 64k */
1781 SYSCTL_INT(_net_inet_tcp, TCPCTL_RECVSPACE, recvspace, CTLFLAG_RW,
1782     &tcp_recvspace , 0, "Maximum incoming TCP datagram size");
1783 
1784 /*
1785  * Attach TCP protocol to socket, allocating internet protocol control
1786  * block, tcp control block, buffer space, and entering CLOSED state.
1787  */
1788 static int
1789 tcp_attach(struct socket *so, struct pru_attach_info *ai)
1790 {
1791 	struct inpcb *inp;
1792 	int error;
1793 	int cpu;
1794 #ifdef INET6
1795 	boolean_t isipv6 = INP_CHECK_SOCKAF(so, AF_INET6);
1796 #endif
1797 
1798 	if (ai != NULL) {
1799 		error = tcp_usr_preattach(so, 0 /* don't care */, ai);
1800 		if (error)
1801 			return (error);
1802 	} else {
1803 		/* Post attach; do nothing */
1804 	}
1805 
1806 	cpu = mycpu->gd_cpuid;
1807 
1808 	/*
1809 	 * Set the default pcbinfo.  This will likely change when we
1810 	 * bind/connect.
1811 	 */
1812 	error = in_pcballoc(so, &tcbinfo[cpu]);
1813 	if (error)
1814 		return (error);
1815 	inp = so->so_pcb;
1816 #ifdef INET6
1817 	if (isipv6)
1818 		inp->in6p_hops = -1;	/* use kernel default */
1819 #endif
1820 	tcp_newtcpcb(inp);
1821 	/* Keep a reference for asynchronized pru_rcvd */
1822 	soreference(so);
1823 	return (0);
1824 }
1825 
1826 /*
1827  * Initiate (or continue) disconnect.
1828  * If embryonic state, just send reset (once).
1829  * If in ``let data drain'' option and linger null, just drop.
1830  * Otherwise (hard), mark socket disconnecting and drop
1831  * current input data; switch states based on user close, and
1832  * send segment to peer (with FIN).
1833  */
1834 static struct tcpcb *
1835 tcp_disconnect(struct tcpcb *tp)
1836 {
1837 	struct socket *so = tp->t_inpcb->inp_socket;
1838 
1839 	if (tp->t_state < TCPS_ESTABLISHED) {
1840 		tp = tcp_close(tp);
1841 	} else if ((so->so_options & SO_LINGER) && so->so_linger == 0) {
1842 		tp = tcp_drop(tp, 0);
1843 	} else {
1844 		lwkt_gettoken(&so->so_rcv.ssb_token);
1845 		soisdisconnecting(so);
1846 		sbflush(&so->so_rcv.sb);
1847 		tp = tcp_usrclosed(tp);
1848 		if (tp)
1849 			tcp_output(tp);
1850 		lwkt_reltoken(&so->so_rcv.ssb_token);
1851 	}
1852 	return (tp);
1853 }
1854 
1855 /*
1856  * User issued close, and wish to trail through shutdown states:
1857  * if never received SYN, just forget it.  If got a SYN from peer,
1858  * but haven't sent FIN, then go to FIN_WAIT_1 state to send peer a FIN.
1859  * If already got a FIN from peer, then almost done; go to LAST_ACK
1860  * state.  In all other cases, have already sent FIN to peer (e.g.
1861  * after PRU_SHUTDOWN), and just have to play tedious game waiting
1862  * for peer to send FIN or not respond to keep-alives, etc.
1863  * We can let the user exit from the close as soon as the FIN is acked.
1864  */
1865 static struct tcpcb *
1866 tcp_usrclosed(struct tcpcb *tp)
1867 {
1868 
1869 	switch (tp->t_state) {
1870 
1871 	case TCPS_CLOSED:
1872 	case TCPS_LISTEN:
1873 		TCP_STATE_CHANGE(tp, TCPS_CLOSED);
1874 		tp = tcp_close(tp);
1875 		break;
1876 
1877 	case TCPS_SYN_SENT:
1878 	case TCPS_SYN_RECEIVED:
1879 		tp->t_flags |= TF_NEEDFIN;
1880 		break;
1881 
1882 	case TCPS_ESTABLISHED:
1883 		TCP_STATE_CHANGE(tp, TCPS_FIN_WAIT_1);
1884 		break;
1885 
1886 	case TCPS_CLOSE_WAIT:
1887 		TCP_STATE_CHANGE(tp, TCPS_LAST_ACK);
1888 		break;
1889 	}
1890 	if (tp && tp->t_state >= TCPS_FIN_WAIT_2) {
1891 		soisdisconnected(tp->t_inpcb->inp_socket);
1892 		/* To prevent the connection hanging in FIN_WAIT_2 forever. */
1893 		if (tp->t_state == TCPS_FIN_WAIT_2) {
1894 			tcp_callout_reset(tp, tp->tt_2msl, tp->t_maxidle,
1895 			    tcp_timer_2msl);
1896 		}
1897 	}
1898 	return (tp);
1899 }
1900