xref: /dragonfly/sys/netinet/tcp_usrreq.c (revision a9783bc6)
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 
604 	if (!prison_remote_ip(td, (struct sockaddr*)sinp)) {
605 		error = EAFNOSUPPORT; /* IPv6 only jail */
606 		goto out;
607 	}
608 
609 	tcp_connect(msg);
610 	/* msg is invalid now */
611 	return;
612 out:
613 	if (msg->connect.nm_m) {
614 		m_freem(msg->connect.nm_m);
615 		msg->connect.nm_m = NULL;
616 	}
617 	if (msg->connect.nm_flags & PRUC_HELDTD)
618 		lwkt_rele(td);
619 	if (error && (msg->connect.nm_flags & PRUC_ASYNC)) {
620 		so->so_error = error;
621 		soisdisconnected(so);
622 	}
623 	lwkt_replymsg(&msg->lmsg, error);
624 }
625 
626 #ifdef INET6
627 
628 static void
629 tcp6_usr_connect(netmsg_t msg)
630 {
631 	struct socket *so = msg->connect.base.nm_so;
632 	struct sockaddr *nam = msg->connect.nm_nam;
633 	struct thread *td = msg->connect.nm_td;
634 	int error = 0;
635 	struct inpcb *inp;
636 	struct tcpcb *tp;
637 	struct sockaddr_in6 *sin6p;
638 
639 	ASSERT_NETISR_NCPUS(mycpuid);
640 
641 	COMMON_START(so, inp, 0);
642 
643 	/*
644 	 * Must disallow TCP ``connections'' to multicast addresses.
645 	 */
646 	sin6p = (struct sockaddr_in6 *)nam;
647 	if (sin6p->sin6_family == AF_INET6
648 	    && IN6_IS_ADDR_MULTICAST(&sin6p->sin6_addr)) {
649 		error = EAFNOSUPPORT;
650 		goto out;
651 	}
652 
653 	if (!prison_remote_ip(td, nam)) {
654 		error = EAFNOSUPPORT; /* IPv4 only jail */
655 		goto out;
656 	}
657 
658 	/* Reject v4-mapped address */
659 	if (IN6_IS_ADDR_V4MAPPED(&sin6p->sin6_addr)) {
660 		error = EADDRNOTAVAIL;
661 		goto out;
662 	}
663 
664 	inp->inp_inc.inc_isipv6 = 1;
665 	tcp6_connect(msg);
666 	/* msg is invalid now */
667 	return;
668 out:
669 	if (msg->connect.nm_m) {
670 		m_freem(msg->connect.nm_m);
671 		msg->connect.nm_m = NULL;
672 	}
673 	lwkt_replymsg(&msg->lmsg, error);
674 }
675 
676 #endif /* INET6 */
677 
678 /*
679  * Initiate disconnect from peer.
680  * If connection never passed embryonic stage, just drop;
681  * else if don't need to let data drain, then can just drop anyways,
682  * else have to begin TCP shutdown process: mark socket disconnecting,
683  * drain unread data, state switch to reflect user close, and
684  * send segment (e.g. FIN) to peer.  Socket will be really disconnected
685  * when peer sends FIN and acks ours.
686  *
687  * SHOULD IMPLEMENT LATER PRU_CONNECT VIA REALLOC TCPCB.
688  */
689 static void
690 tcp_usr_disconnect(netmsg_t msg)
691 {
692 	struct socket *so = msg->disconnect.base.nm_so;
693 	int error = 0;
694 	struct inpcb *inp;
695 	struct tcpcb *tp;
696 
697 	COMMON_START(so, inp, 1);
698 	tp = tcp_disconnect(tp);
699 	COMMON_END(PRU_DISCONNECT);
700 }
701 
702 /*
703  * Accept a connection.  Essentially all the work is
704  * done at higher levels; just return the address
705  * of the peer, storing through addr.
706  */
707 static void
708 tcp_usr_accept(netmsg_t msg)
709 {
710 	struct socket *so = msg->accept.base.nm_so;
711 	struct sockaddr **nam = msg->accept.nm_nam;
712 	int error = 0;
713 	struct inpcb *inp;
714 	struct tcpcb *tp = NULL;
715 	TCPDEBUG0;
716 
717 	inp = so->so_pcb;
718 	if (so->so_state & SS_ISDISCONNECTED) {
719 		error = ECONNABORTED;
720 		goto out;
721 	}
722 	if (inp == NULL) {
723 		error = EINVAL;
724 		goto out;
725 	}
726 
727 	tp = intotcpcb(inp);
728 	TCPDEBUG1();
729 	in_setpeeraddr(so, nam);
730 	COMMON_END(PRU_ACCEPT);
731 }
732 
733 #ifdef INET6
734 static void
735 tcp6_usr_accept(netmsg_t msg)
736 {
737 	struct socket *so = msg->accept.base.nm_so;
738 	struct sockaddr **nam = msg->accept.nm_nam;
739 	int error = 0;
740 	struct inpcb *inp;
741 	struct tcpcb *tp = NULL;
742 	TCPDEBUG0;
743 
744 	inp = so->so_pcb;
745 
746 	if (so->so_state & SS_ISDISCONNECTED) {
747 		error = ECONNABORTED;
748 		goto out;
749 	}
750 	if (inp == NULL) {
751 		error = EINVAL;
752 		goto out;
753 	}
754 	tp = intotcpcb(inp);
755 	TCPDEBUG1();
756 	in6_setpeeraddr(so, nam);
757 	COMMON_END(PRU_ACCEPT);
758 }
759 #endif /* INET6 */
760 
761 /*
762  * Mark the connection as being incapable of further output.
763  */
764 static void
765 tcp_usr_shutdown(netmsg_t msg)
766 {
767 	struct socket *so = msg->shutdown.base.nm_so;
768 	int error = 0;
769 	struct inpcb *inp;
770 	struct tcpcb *tp;
771 
772 	COMMON_START(so, inp, 0);
773 	socantsendmore(so);
774 	tp = tcp_usrclosed(tp);
775 	if (tp)
776 		error = tcp_output(tp);
777 	COMMON_END(PRU_SHUTDOWN);
778 }
779 
780 /*
781  * After a receive, possibly send window update to peer.
782  */
783 static void
784 tcp_usr_rcvd(netmsg_t msg)
785 {
786 	struct socket *so = msg->rcvd.base.nm_so;
787 	int error = 0, noreply = 0;
788 	struct inpcb *inp;
789 	struct tcpcb *tp;
790 
791 	COMMON_START(so, inp, 0);
792 
793 	if (msg->rcvd.nm_pru_flags & PRUR_ASYNC) {
794 		noreply = 1;
795 		so_async_rcvd_reply(so);
796 	}
797 	tcp_output(tp);
798 
799 	COMMON_END1(PRU_RCVD, noreply);
800 }
801 
802 /*
803  * Do a send by putting data in output queue and updating urgent
804  * marker if URG set.  Possibly send more data.  Unlike the other
805  * pru_*() routines, the mbuf chains are our responsibility.  We
806  * must either enqueue them or free them.  The other pru_* routines
807  * generally are caller-frees.
808  */
809 static void
810 tcp_usr_send(netmsg_t msg)
811 {
812 	struct socket *so = msg->send.base.nm_so;
813 	int flags = msg->send.nm_flags;
814 	struct mbuf *m = msg->send.nm_m;
815 	int error = 0;
816 	struct inpcb *inp;
817 	struct tcpcb *tp;
818 	TCPDEBUG0;
819 
820 	KKASSERT(msg->send.nm_control == NULL);
821 	KKASSERT(msg->send.nm_addr == NULL);
822 	KKASSERT((flags & PRUS_FREEADDR) == 0);
823 
824 	inp = so->so_pcb;
825 
826 	if (inp == NULL) {
827 		/*
828 		 * OOPS! we lost a race, the TCP session got reset after
829 		 * we checked SS_CANTSENDMORE, eg: while doing uiomove or a
830 		 * network interrupt in the non-critical section of sosend().
831 		 */
832 		m_freem(m);
833 		error = ECONNRESET;	/* XXX EPIPE? */
834 		tp = NULL;
835 		TCPDEBUG1();
836 		goto out;
837 	}
838 	tp = intotcpcb(inp);
839 	TCPDEBUG1();
840 
841 #ifdef foo
842 	/*
843 	 * This is no longer necessary, since:
844 	 * - sosendtcp() has already checked it for us
845 	 * - It does not work with asynchronized send
846 	 */
847 
848 	/*
849 	 * Don't let too much OOB data build up
850 	 */
851 	if (flags & PRUS_OOB) {
852 		if (ssb_space(&so->so_snd) < -512) {
853 			m_freem(m);
854 			error = ENOBUFS;
855 			goto out;
856 		}
857 	}
858 #endif
859 
860 	/*
861 	 * Pump the data into the socket.
862 	 */
863 	if (m) {
864 		ssb_appendstream(&so->so_snd, m);
865 		sowwakeup(so);
866 	}
867 	if (flags & PRUS_OOB) {
868 		/*
869 		 * According to RFC961 (Assigned Protocols),
870 		 * the urgent pointer points to the last octet
871 		 * of urgent data.  We continue, however,
872 		 * to consider it to indicate the first octet
873 		 * of data past the urgent section.
874 		 * Otherwise, snd_up should be one lower.
875 		 */
876 		tp->snd_up = tp->snd_una + so->so_snd.ssb_cc;
877 		tp->t_flags |= TF_FORCE;
878 		error = tcp_output(tp);
879 		tp->t_flags &= ~TF_FORCE;
880 	} else {
881 		if (flags & PRUS_EOF) {
882 			/*
883 			 * Close the send side of the connection after
884 			 * the data is sent.
885 			 */
886 			socantsendmore(so);
887 			tp = tcp_usrclosed(tp);
888 		}
889 		if (tp != NULL && !tcp_output_pending(tp)) {
890 			if (flags & PRUS_MORETOCOME)
891 				tp->t_flags |= TF_MORETOCOME;
892 			error = tcp_output_fair(tp);
893 			if (flags & PRUS_MORETOCOME)
894 				tp->t_flags &= ~TF_MORETOCOME;
895 		}
896 	}
897 	COMMON_END1((flags & PRUS_OOB) ? PRU_SENDOOB :
898 		   ((flags & PRUS_EOF) ? PRU_SEND_EOF : PRU_SEND),
899 		   (flags & PRUS_NOREPLY));
900 }
901 
902 /*
903  * NOTE: (so) is referenced from soabort*() and netmsg_pru_abort()
904  *	 will sofree() it when we return.
905  */
906 static void
907 tcp_usr_abort(netmsg_t msg)
908 {
909 	struct socket *so = msg->abort.base.nm_so;
910 	int error = 0;
911 	struct inpcb *inp;
912 	struct tcpcb *tp;
913 
914 	COMMON_START(so, inp, 1);
915 	tp = tcp_drop(tp, ECONNABORTED);
916 	COMMON_END(PRU_ABORT);
917 }
918 
919 /*
920  * Receive out-of-band data.
921  */
922 static void
923 tcp_usr_rcvoob(netmsg_t msg)
924 {
925 	struct socket *so = msg->rcvoob.base.nm_so;
926 	struct mbuf *m = msg->rcvoob.nm_m;
927 	int flags = msg->rcvoob.nm_flags;
928 	int error = 0;
929 	struct inpcb *inp;
930 	struct tcpcb *tp;
931 
932 	COMMON_START(so, inp, 0);
933 	if ((so->so_oobmark == 0 &&
934 	     (so->so_state & SS_RCVATMARK) == 0) ||
935 	    so->so_options & SO_OOBINLINE ||
936 	    tp->t_oobflags & TCPOOB_HADDATA) {
937 		error = EINVAL;
938 		goto out;
939 	}
940 	if ((tp->t_oobflags & TCPOOB_HAVEDATA) == 0) {
941 		error = EWOULDBLOCK;
942 		goto out;
943 	}
944 	m->m_len = 1;
945 	*mtod(m, caddr_t) = tp->t_iobc;
946 	if ((flags & MSG_PEEK) == 0)
947 		tp->t_oobflags ^= (TCPOOB_HAVEDATA | TCPOOB_HADDATA);
948 	COMMON_END(PRU_RCVOOB);
949 }
950 
951 static void
952 tcp_usr_savefaddr(struct socket *so, const struct sockaddr *faddr)
953 {
954 	in_savefaddr(so, faddr);
955 }
956 
957 #ifdef INET6
958 static void
959 tcp6_usr_savefaddr(struct socket *so, const struct sockaddr *faddr)
960 {
961 	in6_savefaddr(so, faddr);
962 }
963 #endif
964 
965 static int
966 tcp_usr_preconnect(struct socket *so, const struct sockaddr *nam,
967     struct thread *td __unused)
968 {
969 	const struct sockaddr_in *sinp;
970 
971 	sinp = (const struct sockaddr_in *)nam;
972 	if (sinp->sin_family == AF_INET &&
973 	    IN_MULTICAST(ntohl(sinp->sin_addr.s_addr)))
974 		return EAFNOSUPPORT;
975 
976 	soisconnecting(so);
977 	return 0;
978 }
979 
980 /* xxx - should be const */
981 struct pr_usrreqs tcp_usrreqs = {
982 	.pru_abort = tcp_usr_abort,
983 	.pru_accept = tcp_usr_accept,
984 	.pru_attach = tcp_usr_attach,
985 	.pru_bind = tcp_usr_bind,
986 	.pru_connect = tcp_usr_connect,
987 	.pru_connect2 = pr_generic_notsupp,
988 	.pru_control = in_control_dispatch,
989 	.pru_detach = tcp_usr_detach,
990 	.pru_disconnect = tcp_usr_disconnect,
991 	.pru_listen = tcp_usr_listen,
992 	.pru_peeraddr = in_setpeeraddr_dispatch,
993 	.pru_rcvd = tcp_usr_rcvd,
994 	.pru_rcvoob = tcp_usr_rcvoob,
995 	.pru_send = tcp_usr_send,
996 	.pru_sense = pru_sense_null,
997 	.pru_shutdown = tcp_usr_shutdown,
998 	.pru_sockaddr = in_setsockaddr_dispatch,
999 	.pru_sosend = sosendtcp,
1000 	.pru_soreceive = sorecvtcp,
1001 	.pru_savefaddr = tcp_usr_savefaddr,
1002 	.pru_preconnect = tcp_usr_preconnect,
1003 	.pru_preattach = tcp_usr_preattach
1004 };
1005 
1006 #ifdef INET6
1007 struct pr_usrreqs tcp6_usrreqs = {
1008 	.pru_abort = tcp_usr_abort,
1009 	.pru_accept = tcp6_usr_accept,
1010 	.pru_attach = tcp_usr_attach,
1011 	.pru_bind = tcp6_usr_bind,
1012 	.pru_connect = tcp6_usr_connect,
1013 	.pru_connect2 = pr_generic_notsupp,
1014 	.pru_control = in6_control_dispatch,
1015 	.pru_detach = tcp_usr_detach,
1016 	.pru_disconnect = tcp_usr_disconnect,
1017 	.pru_listen = tcp6_usr_listen,
1018 	.pru_peeraddr = in6_setpeeraddr_dispatch,
1019 	.pru_rcvd = tcp_usr_rcvd,
1020 	.pru_rcvoob = tcp_usr_rcvoob,
1021 	.pru_send = tcp_usr_send,
1022 	.pru_sense = pru_sense_null,
1023 	.pru_shutdown = tcp_usr_shutdown,
1024 	.pru_sockaddr = in6_setsockaddr_dispatch,
1025 	.pru_sosend = sosendtcp,
1026 	.pru_soreceive = sorecvtcp,
1027 	.pru_savefaddr = tcp6_usr_savefaddr
1028 };
1029 #endif /* INET6 */
1030 
1031 static int
1032 tcp_connect_oncpu(struct tcpcb *tp, int flags, struct mbuf *m,
1033 		  const struct sockaddr_in *sin, struct sockaddr_in *if_sin,
1034 		  uint16_t hash)
1035 {
1036 	struct inpcb *inp = tp->t_inpcb, *oinp;
1037 	struct socket *so = inp->inp_socket;
1038 	struct route *ro = &inp->inp_route;
1039 
1040 	KASSERT(inp->inp_pcbinfo == &tcbinfo[mycpu->gd_cpuid],
1041 	    ("pcbinfo mismatch"));
1042 
1043 	oinp = in_pcblookup_hash(inp->inp_pcbinfo,
1044 				 sin->sin_addr, sin->sin_port,
1045 				 (inp->inp_laddr.s_addr != INADDR_ANY ?
1046 				  inp->inp_laddr : if_sin->sin_addr),
1047 				inp->inp_lport, 0, NULL);
1048 	if (oinp != NULL) {
1049 		m_freem(m);
1050 		return (EADDRINUSE);
1051 	}
1052 	if (inp->inp_laddr.s_addr == INADDR_ANY)
1053 		inp->inp_laddr = if_sin->sin_addr;
1054 	KASSERT(inp->inp_faddr.s_addr == sin->sin_addr.s_addr,
1055 	    ("faddr mismatch for reconnect"));
1056 	KASSERT(inp->inp_fport == sin->sin_port,
1057 	    ("fport mismatch for reconnect"));
1058 	in_pcbinsconnhash(inp);
1059 
1060 	inp->inp_flags |= INP_HASH;
1061 	inp->inp_hashval = hash;
1062 
1063 	/*
1064 	 * We are now on the inpcb's owner CPU, if the cached route was
1065 	 * freed because the rtentry's owner CPU is not the current CPU
1066 	 * (e.g. in tcp_connect()), then we try to reallocate it here with
1067 	 * the hope that a rtentry may be cloned from a RTF_PRCLONING
1068 	 * rtentry.
1069 	 */
1070 	if (!(inp->inp_socket->so_options & SO_DONTROUTE) && /*XXX*/
1071 	    ro->ro_rt == NULL) {
1072 		bzero(&ro->ro_dst, sizeof(struct sockaddr_in));
1073 		ro->ro_dst.sa_family = AF_INET;
1074 		ro->ro_dst.sa_len = sizeof(struct sockaddr_in);
1075 		((struct sockaddr_in *)&ro->ro_dst)->sin_addr =
1076 			sin->sin_addr;
1077 		rtalloc(ro);
1078 	}
1079 
1080 	/*
1081 	 * Now that no more errors can occur, change the protocol processing
1082 	 * port to the current thread (which is the correct thread).
1083 	 *
1084 	 * Create TCP timer message now; we are on the tcpcb's owner
1085 	 * CPU/thread.
1086 	 */
1087 	tcp_create_timermsg(tp, &curthread->td_msgport);
1088 
1089 	/*
1090 	 * Compute window scaling to request.  Use a larger scaling then
1091 	 * needed for the initial receive buffer in case the receive buffer
1092 	 * gets expanded.
1093 	 */
1094 	if (tp->request_r_scale < TCP_MIN_WINSHIFT)
1095 		tp->request_r_scale = TCP_MIN_WINSHIFT;
1096 	while (tp->request_r_scale < TCP_MAX_WINSHIFT &&
1097 	       (TCP_MAXWIN << tp->request_r_scale) < so->so_rcv.ssb_hiwat
1098 	) {
1099 		tp->request_r_scale++;
1100 	}
1101 
1102 	soisconnecting(so);
1103 	tcpstat.tcps_connattempt++;
1104 	TCP_STATE_CHANGE(tp, TCPS_SYN_SENT);
1105 	tcp_callout_reset(tp, tp->tt_keep, tp->t_keepinit, tcp_timer_keep);
1106 	tp->iss = tcp_new_isn(tp);
1107 	tcp_sendseqinit(tp);
1108 	if (m) {
1109 		ssb_appendstream(&so->so_snd, m);
1110 		m = NULL;
1111 		if (flags & PRUS_OOB)
1112 			tp->snd_up = tp->snd_una + so->so_snd.ssb_cc;
1113 	}
1114 
1115 	/*
1116 	 * Close the send side of the connection after
1117 	 * the data is sent if flagged.
1118 	 */
1119 	if ((flags & (PRUS_OOB|PRUS_EOF)) == PRUS_EOF) {
1120 		socantsendmore(so);
1121 		tp = tcp_usrclosed(tp);
1122 	}
1123 	return (tcp_output(tp));
1124 }
1125 
1126 /*
1127  * Common subroutine to open a TCP connection to remote host specified
1128  * by struct sockaddr_in in mbuf *nam.  Call in_pcbbind to assign a local
1129  * port number if needed.  Call in_pcbladdr to do the routing and to choose
1130  * a local host address (interface).
1131  * Initialize connection parameters and enter SYN-SENT state.
1132  */
1133 static void
1134 tcp_connect(netmsg_t msg)
1135 {
1136 	struct socket *so = msg->connect.base.nm_so;
1137 	struct sockaddr *nam = msg->connect.nm_nam;
1138 	struct thread *td = msg->connect.nm_td;
1139 	struct sockaddr_in *sin = (struct sockaddr_in *)nam;
1140 	struct sockaddr_in *if_sin = NULL;
1141 	struct inpcb *inp;
1142 	struct tcpcb *tp;
1143 	int error;
1144 	uint16_t hash;
1145 	lwkt_port_t port;
1146 
1147 	COMMON_START(so, inp, 0);
1148 
1149 	/*
1150 	 * Reconnect our pcb if we have to
1151 	 */
1152 	if (msg->connect.nm_flags & PRUC_RECONNECT) {
1153 		msg->connect.nm_flags &= ~PRUC_RECONNECT;
1154 		TCP_STATE_MIGRATE_END(tp);
1155 		in_pcblink(so->so_pcb, &tcbinfo[mycpu->gd_cpuid]);
1156 	} else {
1157 		if (inp->inp_faddr.s_addr != INADDR_ANY) {
1158 			kprintf("inpcb %p, double-connect race\n", inp);
1159 			error = EISCONN;
1160 			if (so->so_state & SS_ISCONNECTING)
1161 				error = EALREADY;
1162 			goto out;
1163 		}
1164 		KASSERT(inp->inp_fport == 0, ("invalid fport"));
1165 	}
1166 
1167 	/*
1168 	 * Select local port, if it is not yet selected.
1169 	 */
1170 	if (inp->inp_lport == 0) {
1171 		KKASSERT(inp->inp_laddr.s_addr == INADDR_ANY);
1172 
1173 		error = in_pcbladdr(inp, nam, &if_sin, td);
1174 		if (error)
1175 			goto out;
1176 		inp->inp_laddr.s_addr = if_sin->sin_addr.s_addr;
1177 		msg->connect.nm_flags |= PRUC_HASLADDR;
1178 
1179 		/*
1180 		 * Install faddr/fport earlier, so that when this
1181 		 * inpcb is installed on to the lport hash, the
1182 		 * 4-tuple contains correct value.
1183 		 *
1184 		 * NOTE: The faddr/fport will have to be installed
1185 		 * after the in_pcbladdr(), which may change them.
1186 		 */
1187 		inp->inp_faddr = sin->sin_addr;
1188 		inp->inp_fport = sin->sin_port;
1189 
1190 		error = in_pcbbind_remote(inp, nam, td);
1191 		if (error)
1192 			goto out;
1193 	}
1194 
1195 	if ((msg->connect.nm_flags & PRUC_HASLADDR) == 0) {
1196 		/*
1197 		 * Rarely used path:
1198 		 * This inpcb was bound before this connect.
1199 		 */
1200 		error = in_pcbladdr(inp, nam, &if_sin, td);
1201 		if (error)
1202 			goto out;
1203 
1204 		/*
1205 		 * Save or refresh the faddr/fport, since they may
1206 		 * be changed by in_pcbladdr().
1207 		 */
1208 		inp->inp_faddr = sin->sin_addr;
1209 		inp->inp_fport = sin->sin_port;
1210 	}
1211 #ifdef INVARIANTS
1212 	else {
1213 		KASSERT(inp->inp_faddr.s_addr == sin->sin_addr.s_addr,
1214 		    ("faddr mismatch for reconnect"));
1215 		KASSERT(inp->inp_fport == sin->sin_port,
1216 		    ("fport mismatch for reconnect"));
1217 	}
1218 #endif
1219 	KKASSERT(inp->inp_socket == so);
1220 
1221 	hash = tcp_addrhash(sin->sin_addr.s_addr, sin->sin_port,
1222 			    (inp->inp_laddr.s_addr != INADDR_ANY ?
1223 			     inp->inp_laddr.s_addr : if_sin->sin_addr.s_addr),
1224 			    inp->inp_lport);
1225 	port = netisr_hashport(hash);
1226 
1227 	if (port != &curthread->td_msgport) {
1228 		lwkt_msg_t lmsg = &msg->connect.base.lmsg;
1229 
1230 		/*
1231 		 * in_pcbladdr() may have allocated a route entry for us
1232 		 * on the current CPU, but we need a route entry on the
1233 		 * inpcb's owner CPU, so free it here.
1234 		 */
1235 		in_pcbresetroute(inp);
1236 
1237 		/*
1238 		 * We are moving the protocol processing port the socket
1239 		 * is on, we have to unlink here and re-link on the
1240 		 * target cpu.
1241 		 */
1242 		in_pcbunlink(so->so_pcb, &tcbinfo[mycpu->gd_cpuid]);
1243 		msg->connect.nm_flags |= PRUC_RECONNECT;
1244 		msg->connect.base.nm_dispatch = tcp_connect;
1245 
1246 		TCP_STATE_MIGRATE_START(tp);
1247 
1248 		/*
1249 		 * Use message put done receipt to change this socket's
1250 		 * so_port, i.e. _after_ this message was put onto the
1251 		 * target netisr's msgport but _before_ the message could
1252 		 * be pulled from the target netisr's msgport, so that:
1253 		 * - The upper half (socket code) will not see the new
1254 		 *   msgport before this message reaches the new msgport
1255 		 *   and messages for this socket will be ordered.
1256 		 * - This message will see the new msgport, when its
1257 		 *   handler is called in the target netisr.
1258 		 *
1259 		 * NOTE:
1260 		 * We MUST use messege put done receipt to change this
1261 		 * socket's so_port:
1262 		 * If we changed the so_port in this netisr after the
1263 		 * lwkt_forwardmsg (so messages for this socket will be
1264 		 * ordered) and changed the so_port in the target netisr
1265 		 * at the very beginning of this message's handler, we
1266 		 * would suffer so_port overwritten race, given this
1267 		 * message might be forwarded again.
1268 		 *
1269 		 * NOTE:
1270 		 * This mechanism depends on that the netisr's msgport
1271 		 * is spin msgport (currently it is :).
1272 		 *
1273 		 * If the upper half saw the new msgport before this
1274 		 * message reached the target netisr's msgport, the
1275 		 * messages sent from the upper half could reach the new
1276 		 * msgport before this message, thus there would be
1277 		 * message reordering.  The worst case could be soclose()
1278 		 * saw the new msgport and the detach message could reach
1279 		 * the new msgport before this message, i.e. the inpcb
1280 		 * could have been destroyed when this message was still
1281 		 * pending on or on its way to the new msgport.  Other
1282 		 * weird cases could also happen, e.g. inpcb->inp_pcbinfo,
1283 		 * since we have unlinked this inpcb from the current
1284 		 * pcbinfo first.
1285 		 */
1286 		lwkt_setmsg_receipt(lmsg, tcp_sosetport);
1287 		lwkt_forwardmsg(port, lmsg);
1288 		/* msg invalid now */
1289 		return;
1290 	} else if (msg->connect.nm_flags & PRUC_HELDTD) {
1291 		/*
1292 		 * The original thread is no longer needed; release it.
1293 		 */
1294 		lwkt_rele(td);
1295 		msg->connect.nm_flags &= ~PRUC_HELDTD;
1296 	}
1297 	error = tcp_connect_oncpu(tp, msg->connect.nm_sndflags,
1298 				  msg->connect.nm_m, sin, if_sin, hash);
1299 	msg->connect.nm_m = NULL;
1300 out:
1301 	if (msg->connect.nm_m) {
1302 		m_freem(msg->connect.nm_m);
1303 		msg->connect.nm_m = NULL;
1304 	}
1305 	if (msg->connect.nm_flags & PRUC_HELDTD)
1306 		lwkt_rele(td);
1307 	if (error && (msg->connect.nm_flags & PRUC_ASYNC)) {
1308 		so->so_error = error;
1309 		soisdisconnected(so);
1310 	}
1311 	lwkt_replymsg(&msg->connect.base.lmsg, error);
1312 	/* msg invalid now */
1313 }
1314 
1315 #ifdef INET6
1316 
1317 static void
1318 tcp6_connect(netmsg_t msg)
1319 {
1320 	struct tcpcb *tp;
1321 	struct socket *so = msg->connect.base.nm_so;
1322 	struct sockaddr *nam = msg->connect.nm_nam;
1323 	struct thread *td = msg->connect.nm_td;
1324 	struct inpcb *inp;
1325 	struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)nam;
1326 	struct in6_addr *addr6;
1327 	lwkt_port_t port;
1328 	int error;
1329 
1330 	COMMON_START(so, inp, 0);
1331 
1332 	/*
1333 	 * Reconnect our pcb if we have to
1334 	 */
1335 	if (msg->connect.nm_flags & PRUC_RECONNECT) {
1336 		msg->connect.nm_flags &= ~PRUC_RECONNECT;
1337 		TCP_STATE_MIGRATE_END(tp);
1338 		in_pcblink(so->so_pcb, &tcbinfo[mycpu->gd_cpuid]);
1339 	}
1340 
1341 	/*
1342 	 * Bind if we have to
1343 	 */
1344 	if (inp->inp_lport == 0) {
1345 		error = in6_pcbbind(inp, NULL, td);
1346 		if (error)
1347 			goto out;
1348 	}
1349 
1350 	/*
1351 	 * Cannot simply call in_pcbconnect, because there might be an
1352 	 * earlier incarnation of this same connection still in
1353 	 * TIME_WAIT state, creating an ADDRINUSE error.
1354 	 */
1355 	error = in6_pcbladdr(inp, nam, &addr6, td);
1356 	if (error)
1357 		goto out;
1358 
1359 	port = tcp6_addrport();	/* XXX hack for now, always cpu0 */
1360 
1361 	if (port != &curthread->td_msgport) {
1362 		lwkt_msg_t lmsg = &msg->connect.base.lmsg;
1363 
1364 		/*
1365 		 * in_pcbladdr() may have allocated a route entry for us
1366 		 * on the current CPU, but we need a route entry on the
1367 		 * inpcb's owner CPU, so free it here.
1368 		 */
1369 		in_pcbresetroute(inp);
1370 
1371 		in_pcbunlink(so->so_pcb, &tcbinfo[mycpu->gd_cpuid]);
1372 		msg->connect.nm_flags |= PRUC_RECONNECT;
1373 		msg->connect.base.nm_dispatch = tcp6_connect;
1374 
1375 		TCP_STATE_MIGRATE_START(tp);
1376 
1377 		/* See the related comment in tcp_connect() */
1378 		lwkt_setmsg_receipt(lmsg, tcp_sosetport);
1379 		lwkt_forwardmsg(port, lmsg);
1380 		/* msg invalid now */
1381 		return;
1382 	}
1383 	error = tcp6_connect_oncpu(tp, msg->connect.nm_sndflags,
1384 				   &msg->connect.nm_m, sin6, addr6);
1385 	/* nm_m may still be intact */
1386 out:
1387 	if (msg->connect.nm_m) {
1388 		m_freem(msg->connect.nm_m);
1389 		msg->connect.nm_m = NULL;
1390 	}
1391 	lwkt_replymsg(&msg->connect.base.lmsg, error);
1392 	/* msg invalid now */
1393 }
1394 
1395 static int
1396 tcp6_connect_oncpu(struct tcpcb *tp, int flags, struct mbuf **mp,
1397 		   struct sockaddr_in6 *sin6, struct in6_addr *addr6)
1398 {
1399 	struct mbuf *m = *mp;
1400 	struct inpcb *inp = tp->t_inpcb;
1401 	struct socket *so = inp->inp_socket;
1402 	struct inpcb *oinp;
1403 
1404 	/*
1405 	 * Cannot simply call in_pcbconnect, because there might be an
1406 	 * earlier incarnation of this same connection still in
1407 	 * TIME_WAIT state, creating an ADDRINUSE error.
1408 	 */
1409 	oinp = in6_pcblookup_hash(inp->inp_pcbinfo,
1410 				  &sin6->sin6_addr, sin6->sin6_port,
1411 				  (IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr) ?
1412 				      addr6 : &inp->in6p_laddr),
1413 				  inp->inp_lport,  0, NULL);
1414 	if (oinp)
1415 		return (EADDRINUSE);
1416 
1417 	if (IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr))
1418 		inp->in6p_laddr = *addr6;
1419 	inp->in6p_faddr = sin6->sin6_addr;
1420 	inp->inp_fport = sin6->sin6_port;
1421 	if ((sin6->sin6_flowinfo & IPV6_FLOWINFO_MASK) != 0)
1422 		inp->in6p_flowinfo = sin6->sin6_flowinfo;
1423 	in_pcbinsconnhash(inp);
1424 
1425 	/*
1426 	 * Now that no more errors can occur, change the protocol processing
1427 	 * port to the current thread (which is the correct thread).
1428 	 *
1429 	 * Create TCP timer message now; we are on the tcpcb's owner
1430 	 * CPU/thread.
1431 	 */
1432 	tcp_create_timermsg(tp, &curthread->td_msgport);
1433 
1434 	/* Compute window scaling to request.  */
1435 	if (tp->request_r_scale < TCP_MIN_WINSHIFT)
1436 		tp->request_r_scale = TCP_MIN_WINSHIFT;
1437 	while (tp->request_r_scale < TCP_MAX_WINSHIFT &&
1438 	    (TCP_MAXWIN << tp->request_r_scale) < so->so_rcv.ssb_hiwat) {
1439 		tp->request_r_scale++;
1440 	}
1441 
1442 	soisconnecting(so);
1443 	tcpstat.tcps_connattempt++;
1444 	TCP_STATE_CHANGE(tp, TCPS_SYN_SENT);
1445 	tcp_callout_reset(tp, tp->tt_keep, tp->t_keepinit, tcp_timer_keep);
1446 	tp->iss = tcp_new_isn(tp);
1447 	tcp_sendseqinit(tp);
1448 	if (m) {
1449 		ssb_appendstream(&so->so_snd, m);
1450 		*mp = NULL;
1451 		if (flags & PRUS_OOB)
1452 			tp->snd_up = tp->snd_una + so->so_snd.ssb_cc;
1453 	}
1454 
1455 	/*
1456 	 * Close the send side of the connection after
1457 	 * the data is sent if flagged.
1458 	 */
1459 	if ((flags & (PRUS_OOB|PRUS_EOF)) == PRUS_EOF) {
1460 		socantsendmore(so);
1461 		tp = tcp_usrclosed(tp);
1462 	}
1463 	return (tcp_output(tp));
1464 }
1465 
1466 #endif /* INET6 */
1467 
1468 /*
1469  * The new sockopt interface makes it possible for us to block in the
1470  * copyin/out step (if we take a page fault).  Taking a page fault while
1471  * in a critical section is probably a Bad Thing.  (Since sockets and pcbs
1472  * both now use TSM, there probably isn't any need for this function to
1473  * run in a critical section any more.  This needs more examination.)
1474  */
1475 void
1476 tcp_ctloutput(netmsg_t msg)
1477 {
1478 	struct socket *so = msg->base.nm_so;
1479 	struct sockopt *sopt = msg->ctloutput.nm_sopt;
1480 	struct thread *td = NULL;
1481 	int	error, opt, optval, opthz;
1482 	struct	inpcb *inp;
1483 	struct	tcpcb *tp;
1484 
1485 	if (msg->ctloutput.nm_flags & PRCO_HELDTD)
1486 		td = sopt->sopt_td;
1487 
1488 	error = 0;
1489 	inp = so->so_pcb;
1490 	if (inp == NULL) {
1491 		error = ECONNRESET;
1492 		goto done;
1493 	}
1494 	tp = intotcpcb(inp);
1495 
1496 	/* Get socket's owner cpuid hint */
1497 	if (sopt->sopt_level == SOL_SOCKET &&
1498 	    sopt->sopt_dir == SOPT_GET &&
1499 	    sopt->sopt_name == SO_CPUHINT) {
1500 		if (tp->t_flags & TF_LISTEN) {
1501 			/*
1502 			 * Listen sockets owner cpuid is always 0,
1503 			 * which does not make sense if SO_REUSEPORT
1504 			 * is not set.
1505 			 *
1506 			 * NOTE: inp_lgrpindex is _not_ assigned in jail.
1507 			 */
1508 			if ((so->so_options & SO_REUSEPORT) &&
1509 			    inp->inp_lgrpindex >= 0)
1510 				optval = inp->inp_lgrpindex % netisr_ncpus;
1511 			else
1512 				optval = -1; /* no hint */
1513 		} else {
1514 			optval = mycpuid;
1515 		}
1516 		soopt_from_kbuf(sopt, &optval, sizeof(optval));
1517 		goto done;
1518 	}
1519 
1520 	if (sopt->sopt_level != IPPROTO_TCP) {
1521 		if (sopt->sopt_level == IPPROTO_IP) {
1522 			switch (sopt->sopt_name) {
1523 			case IP_MULTICAST_IF:
1524 			case IP_MULTICAST_VIF:
1525 			case IP_MULTICAST_TTL:
1526 			case IP_MULTICAST_LOOP:
1527 			case IP_ADD_MEMBERSHIP:
1528 			case IP_DROP_MEMBERSHIP:
1529 				/*
1530 				 * Multicast does not make sense on
1531 				 * TCP sockets.
1532 				 */
1533 				error = EOPNOTSUPP;
1534 				goto done;
1535 			}
1536 		}
1537 #ifdef INET6
1538 		if (INP_CHECK_SOCKAF(so, AF_INET6))
1539 			ip6_ctloutput_dispatch(msg);
1540 		else
1541 #endif /* INET6 */
1542 		ip_ctloutput(msg);
1543 		/* msg invalid now */
1544 		if (td != NULL)
1545 			lwkt_rele(td);
1546 		return;
1547 	}
1548 
1549 	switch (sopt->sopt_dir) {
1550 	case SOPT_SET:
1551 		error = soopt_to_kbuf(sopt, &optval, sizeof optval,
1552 				      sizeof optval);
1553 		if (error)
1554 			break;
1555 		switch (sopt->sopt_name) {
1556 		case TCP_FASTKEEP:
1557 			if (optval > 0)
1558 				tp->t_keepidle = tp->t_keepintvl;
1559 			else
1560 				tp->t_keepidle = tcp_keepidle;
1561 			tcp_timer_keep_activity(tp, 0);
1562 			break;
1563 #ifdef TCP_SIGNATURE
1564 		case TCP_SIGNATURE_ENABLE:
1565 			if (tp->t_state == TCPS_CLOSED) {
1566 				/*
1567 				 * This is the only safe state that this
1568 				 * option could be changed.  Some segments
1569 				 * could already have been sent in other
1570 				 * states.
1571 				 */
1572 				if (optval > 0)
1573 					tp->t_flags |= TF_SIGNATURE;
1574 				else
1575 					tp->t_flags &= ~TF_SIGNATURE;
1576 			} else {
1577 				error = EOPNOTSUPP;
1578 			}
1579 			break;
1580 #endif /* TCP_SIGNATURE */
1581 		case TCP_NODELAY:
1582 		case TCP_NOOPT:
1583 			switch (sopt->sopt_name) {
1584 			case TCP_NODELAY:
1585 				opt = TF_NODELAY;
1586 				break;
1587 			case TCP_NOOPT:
1588 				opt = TF_NOOPT;
1589 				break;
1590 			default:
1591 				opt = 0; /* dead code to fool gcc */
1592 				break;
1593 			}
1594 
1595 			if (optval)
1596 				tp->t_flags |= opt;
1597 			else
1598 				tp->t_flags &= ~opt;
1599 			break;
1600 
1601 		case TCP_NOPUSH:
1602 			if (tcp_disable_nopush)
1603 				break;
1604 			if (optval)
1605 				tp->t_flags |= TF_NOPUSH;
1606 			else {
1607 				tp->t_flags &= ~TF_NOPUSH;
1608 				error = tcp_output(tp);
1609 			}
1610 			break;
1611 
1612 		case TCP_MAXSEG:
1613 			/*
1614 			 * Must be between 0 and maxseg.  If the requested
1615 			 * maxseg is too small to satisfy the desired minmss,
1616 			 * pump it up (silently so sysctl modifications of
1617 			 * minmss do not create unexpected program failures).
1618 			 * Handle degenerate cases.
1619 			 */
1620 			if (optval > 0 && optval <= tp->t_maxseg) {
1621 				if (optval + 40 < tcp_minmss) {
1622 					optval = tcp_minmss - 40;
1623 					if (optval < 0)
1624 						optval = 1;
1625 				}
1626 				tp->t_maxseg = optval;
1627 			} else {
1628 				error = EINVAL;
1629 			}
1630 			break;
1631 
1632 		case TCP_KEEPINIT:
1633 		case TCP_KEEPIDLE:
1634 		case TCP_KEEPINTVL:
1635 			if (optval < 1 || optval > MAXKEEPALIVE) {
1636 				error = EINVAL;
1637 				break;
1638 			}
1639 			opthz = optval * hz;
1640 
1641 			switch (sopt->sopt_name) {
1642 			case TCP_KEEPINIT:
1643 				tp->t_keepinit = opthz;
1644 				break;
1645 			case TCP_KEEPIDLE:
1646 				tp->t_keepidle = opthz;
1647 				tcp_timer_keep_activity(tp, 0);
1648 				break;
1649 			case TCP_KEEPINTVL:
1650 				tp->t_keepintvl = opthz;
1651 				tp->t_maxidle = tp->t_keepintvl * tp->t_keepcnt;
1652 				break;
1653 			}
1654 			break;
1655 
1656 		case TCP_KEEPCNT:
1657 			if (optval < 1 || optval > MAXKEEPCNT) {
1658 				error = EINVAL;
1659 				break;
1660 			}
1661 			tp->t_keepcnt = optval;
1662 			tp->t_maxidle = tp->t_keepintvl * tp->t_keepcnt;
1663 			break;
1664 
1665 		default:
1666 			error = ENOPROTOOPT;
1667 			break;
1668 		}
1669 		break;
1670 
1671 	case SOPT_GET:
1672 		switch (sopt->sopt_name) {
1673 #ifdef TCP_SIGNATURE
1674 		case TCP_SIGNATURE_ENABLE:
1675 			optval = (tp->t_flags & TF_SIGNATURE) ? 1 : 0;
1676 			break;
1677 #endif /* TCP_SIGNATURE */
1678 		case TCP_NODELAY:
1679 			optval = tp->t_flags & TF_NODELAY;
1680 			break;
1681 		case TCP_MAXSEG:
1682 			optval = tp->t_maxseg;
1683 			break;
1684 		case TCP_NOOPT:
1685 			optval = tp->t_flags & TF_NOOPT;
1686 			break;
1687 		case TCP_NOPUSH:
1688 			optval = tp->t_flags & TF_NOPUSH;
1689 			break;
1690 		case TCP_KEEPINIT:
1691 			optval = tp->t_keepinit / hz;
1692 			break;
1693 		case TCP_KEEPIDLE:
1694 			optval = tp->t_keepidle / hz;
1695 			break;
1696 		case TCP_KEEPINTVL:
1697 			optval = tp->t_keepintvl / hz;
1698 			break;
1699 		case TCP_KEEPCNT:
1700 			optval = tp->t_keepcnt;
1701 			break;
1702 		default:
1703 			error = ENOPROTOOPT;
1704 			break;
1705 		}
1706 		if (error == 0)
1707 			soopt_from_kbuf(sopt, &optval, sizeof optval);
1708 		break;
1709 	}
1710 done:
1711 	if (td != NULL)
1712 		lwkt_rele(td);
1713 	lwkt_replymsg(&msg->lmsg, error);
1714 }
1715 
1716 struct netmsg_tcp_ctloutput {
1717 	struct netmsg_pr_ctloutput ctloutput;
1718 	struct sockopt		sopt;
1719 	int			sopt_val;
1720 };
1721 
1722 /*
1723  * Allocate netmsg_pr_ctloutput for asynchronous tcp_ctloutput.
1724  */
1725 struct netmsg_pr_ctloutput *
1726 tcp_ctloutmsg(struct sockopt *sopt)
1727 {
1728 	struct netmsg_tcp_ctloutput *msg;
1729 	int flags = 0, error;
1730 
1731 	KASSERT(sopt->sopt_dir == SOPT_SET, ("not from ctloutput"));
1732 
1733 	/* Only small set of options allows asynchronous setting. */
1734 	if (sopt->sopt_level != IPPROTO_TCP)
1735 		return NULL;
1736 	switch (sopt->sopt_name) {
1737 	case TCP_NODELAY:
1738 	case TCP_NOOPT:
1739 	case TCP_NOPUSH:
1740 	case TCP_FASTKEEP:
1741 		break;
1742 	default:
1743 		return NULL;
1744 	}
1745 
1746 	msg = kmalloc(sizeof(*msg), M_LWKTMSG, M_WAITOK | M_NULLOK);
1747 	if (msg == NULL) {
1748 		/* Fallback to synchronous tcp_ctloutput */
1749 		return NULL;
1750 	}
1751 
1752 	/* Save the sockopt */
1753 	msg->sopt = *sopt;
1754 
1755 	/* Fixup the sopt.sopt_val ptr */
1756 	error = sooptcopyin(sopt, &msg->sopt_val,
1757 	    sizeof(msg->sopt_val), sizeof(msg->sopt_val));
1758 	if (error) {
1759 		kfree(msg, M_LWKTMSG);
1760 		return NULL;
1761 	}
1762 	msg->sopt.sopt_val = &msg->sopt_val;
1763 
1764 	/* Hold the current thread */
1765 	if (msg->sopt.sopt_td != NULL) {
1766 		flags |= PRCO_HELDTD;
1767 		lwkt_hold(msg->sopt.sopt_td);
1768 	}
1769 
1770 	msg->ctloutput.nm_flags = flags;
1771 	msg->ctloutput.nm_sopt = &msg->sopt;
1772 
1773 	return &msg->ctloutput;
1774 }
1775 
1776 /*
1777  * tcp_sendspace and tcp_recvspace are the default send and receive window
1778  * sizes, respectively.  These are obsolescent (this information should
1779  * be set by the route).
1780  *
1781  * Use a default that does not require tcp window scaling to be turned
1782  * on.  Individual programs or the administrator can increase the default.
1783  */
1784 u_long	tcp_sendspace = 57344;	/* largest multiple of PAGE_SIZE < 64k */
1785 SYSCTL_INT(_net_inet_tcp, TCPCTL_SENDSPACE, sendspace, CTLFLAG_RW,
1786     &tcp_sendspace , 0, "Maximum outgoing TCP datagram size");
1787 u_long	tcp_recvspace = 57344;	/* largest multiple of PAGE_SIZE < 64k */
1788 SYSCTL_INT(_net_inet_tcp, TCPCTL_RECVSPACE, recvspace, CTLFLAG_RW,
1789     &tcp_recvspace , 0, "Maximum incoming TCP datagram size");
1790 
1791 /*
1792  * Attach TCP protocol to socket, allocating internet protocol control
1793  * block, tcp control block, buffer space, and entering CLOSED state.
1794  */
1795 static int
1796 tcp_attach(struct socket *so, struct pru_attach_info *ai)
1797 {
1798 	struct inpcb *inp;
1799 	int error;
1800 	int cpu;
1801 #ifdef INET6
1802 	boolean_t isipv6 = INP_CHECK_SOCKAF(so, AF_INET6);
1803 #endif
1804 
1805 	if (ai != NULL) {
1806 		error = tcp_usr_preattach(so, 0 /* don't care */, ai);
1807 		if (error)
1808 			return (error);
1809 	} else {
1810 		/* Post attach; do nothing */
1811 	}
1812 
1813 	cpu = mycpu->gd_cpuid;
1814 
1815 	/*
1816 	 * Set the default pcbinfo.  This will likely change when we
1817 	 * bind/connect.
1818 	 */
1819 	error = in_pcballoc(so, &tcbinfo[cpu]);
1820 	if (error)
1821 		return (error);
1822 	inp = so->so_pcb;
1823 #ifdef INET6
1824 	if (isipv6)
1825 		inp->in6p_hops = -1;	/* use kernel default */
1826 #endif
1827 	tcp_newtcpcb(inp);
1828 	/* Keep a reference for asynchronized pru_rcvd */
1829 	soreference(so);
1830 	return (0);
1831 }
1832 
1833 /*
1834  * Initiate (or continue) disconnect.
1835  * If embryonic state, just send reset (once).
1836  * If in ``let data drain'' option and linger null, just drop.
1837  * Otherwise (hard), mark socket disconnecting and drop
1838  * current input data; switch states based on user close, and
1839  * send segment to peer (with FIN).
1840  */
1841 static struct tcpcb *
1842 tcp_disconnect(struct tcpcb *tp)
1843 {
1844 	struct socket *so = tp->t_inpcb->inp_socket;
1845 
1846 	if (tp->t_state < TCPS_ESTABLISHED) {
1847 		tp = tcp_close(tp);
1848 	} else if ((so->so_options & SO_LINGER) && so->so_linger == 0) {
1849 		tp = tcp_drop(tp, 0);
1850 	} else {
1851 		lwkt_gettoken(&so->so_rcv.ssb_token);
1852 		soisdisconnecting(so);
1853 		sbflush(&so->so_rcv.sb);
1854 		tp = tcp_usrclosed(tp);
1855 		if (tp)
1856 			tcp_output(tp);
1857 		lwkt_reltoken(&so->so_rcv.ssb_token);
1858 	}
1859 	return (tp);
1860 }
1861 
1862 /*
1863  * User issued close, and wish to trail through shutdown states:
1864  * if never received SYN, just forget it.  If got a SYN from peer,
1865  * but haven't sent FIN, then go to FIN_WAIT_1 state to send peer a FIN.
1866  * If already got a FIN from peer, then almost done; go to LAST_ACK
1867  * state.  In all other cases, have already sent FIN to peer (e.g.
1868  * after PRU_SHUTDOWN), and just have to play tedious game waiting
1869  * for peer to send FIN or not respond to keep-alives, etc.
1870  * We can let the user exit from the close as soon as the FIN is acked.
1871  */
1872 static struct tcpcb *
1873 tcp_usrclosed(struct tcpcb *tp)
1874 {
1875 
1876 	switch (tp->t_state) {
1877 
1878 	case TCPS_CLOSED:
1879 	case TCPS_LISTEN:
1880 		TCP_STATE_CHANGE(tp, TCPS_CLOSED);
1881 		tp = tcp_close(tp);
1882 		break;
1883 
1884 	case TCPS_SYN_SENT:
1885 	case TCPS_SYN_RECEIVED:
1886 		tp->t_flags |= TF_NEEDFIN;
1887 		break;
1888 
1889 	case TCPS_ESTABLISHED:
1890 		TCP_STATE_CHANGE(tp, TCPS_FIN_WAIT_1);
1891 		break;
1892 
1893 	case TCPS_CLOSE_WAIT:
1894 		TCP_STATE_CHANGE(tp, TCPS_LAST_ACK);
1895 		break;
1896 	}
1897 	if (tp && tp->t_state >= TCPS_FIN_WAIT_2) {
1898 		soisdisconnected(tp->t_inpcb->inp_socket);
1899 		/* To prevent the connection hanging in FIN_WAIT_2 forever. */
1900 		if (tp->t_state == TCPS_FIN_WAIT_2) {
1901 			tcp_callout_reset(tp, tp->tt_2msl, tp->t_maxidle,
1902 			    tcp_timer_2msl);
1903 		}
1904 	}
1905 	return (tp);
1906 }
1907