1 /* $NetBSD: tcp_timer.c,v 1.99 2022/11/04 09:00:58 ozaki-r Exp $ */
2
3 /*
4 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the project nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32 /*-
33 * Copyright (c) 1997, 1998, 2001, 2005 The NetBSD Foundation, Inc.
34 * All rights reserved.
35 *
36 * This code is derived from software contributed to The NetBSD Foundation
37 * by Jason R. Thorpe and Kevin M. Lahey of the Numerical Aerospace Simulation
38 * Facility, NASA Ames Research Center.
39 * This code is derived from software contributed to The NetBSD Foundation
40 * by Charles M. Hannum.
41 *
42 * Redistribution and use in source and binary forms, with or without
43 * modification, are permitted provided that the following conditions
44 * are met:
45 * 1. Redistributions of source code must retain the above copyright
46 * notice, this list of conditions and the following disclaimer.
47 * 2. Redistributions in binary form must reproduce the above copyright
48 * notice, this list of conditions and the following disclaimer in the
49 * documentation and/or other materials provided with the distribution.
50 *
51 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
52 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
53 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
54 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
55 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
56 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
57 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
58 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
59 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
60 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
61 * POSSIBILITY OF SUCH DAMAGE.
62 */
63
64 /*
65 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995
66 * The Regents of the University of California. All rights reserved.
67 *
68 * Redistribution and use in source and binary forms, with or without
69 * modification, are permitted provided that the following conditions
70 * are met:
71 * 1. Redistributions of source code must retain the above copyright
72 * notice, this list of conditions and the following disclaimer.
73 * 2. Redistributions in binary form must reproduce the above copyright
74 * notice, this list of conditions and the following disclaimer in the
75 * documentation and/or other materials provided with the distribution.
76 * 3. Neither the name of the University nor the names of its contributors
77 * may be used to endorse or promote products derived from this software
78 * without specific prior written permission.
79 *
80 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
81 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
82 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
83 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
84 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
85 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
86 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
87 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
88 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
89 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
90 * SUCH DAMAGE.
91 *
92 * @(#)tcp_timer.c 8.2 (Berkeley) 5/24/95
93 */
94
95 #include <sys/cdefs.h>
96 __KERNEL_RCSID(0, "$NetBSD: tcp_timer.c,v 1.99 2022/11/04 09:00:58 ozaki-r Exp $");
97
98 #ifdef _KERNEL_OPT
99 #include "opt_inet.h"
100 #include "opt_tcp_debug.h"
101 #include "opt_net_mpsafe.h"
102 #endif
103
104 #include <sys/param.h>
105 #include <sys/systm.h>
106 #include <sys/mbuf.h>
107 #include <sys/socket.h>
108 #include <sys/socketvar.h>
109 #include <sys/protosw.h>
110 #include <sys/errno.h>
111 #include <sys/kernel.h>
112 #include <sys/callout.h>
113 #include <sys/workqueue.h>
114 #include <sys/cprng.h>
115
116 #include <net/if.h>
117
118 #include <netinet/in.h>
119 #include <netinet/in_systm.h>
120 #include <netinet/ip.h>
121 #include <netinet/in_pcb.h>
122 #include <netinet/ip_var.h>
123 #include <netinet/ip_icmp.h>
124
125 #ifdef INET6
126 #include <netinet/ip6.h>
127 #include <netinet6/in6_pcb.h>
128 #endif
129
130 #include <netinet/tcp.h>
131 #include <netinet/tcp_fsm.h>
132 #include <netinet/tcp_seq.h>
133 #include <netinet/tcp_timer.h>
134 #include <netinet/tcp_var.h>
135 #include <netinet/tcp_private.h>
136 #include <netinet/tcp_congctl.h>
137 #ifdef TCP_DEBUG
138 #include <netinet/tcp_debug.h>
139 #endif
140
141 /*
142 * Various tunable timer parameters. These are initialized in tcp_init(),
143 * unless they are patched.
144 */
145 u_int tcp_keepinit = 0;
146 u_int tcp_keepidle = 0;
147 u_int tcp_keepintvl = 0;
148 u_int tcp_keepcnt = 0; /* max idle probes */
149
150 int tcp_maxpersistidle = 0; /* max idle time in persist */
151
152 static callout_t tcp_slowtimo_ch;
153 #ifdef NET_MPSAFE
154 static struct workqueue *tcp_slowtimo_wq;
155 static struct work tcp_slowtimo_wk;
156 #endif
157
158 static void tcp_slowtimo_work(struct work *, void *);
159 static void tcp_slowtimo(void *);
160
161 /*
162 * Time to delay the ACK. This is initialized in tcp_init(), unless
163 * its patched.
164 */
165 int tcp_delack_ticks = 0;
166
167 void tcp_timer_rexmt(void *);
168 void tcp_timer_persist(void *);
169 void tcp_timer_keep(void *);
170 void tcp_timer_2msl(void *);
171
172 const tcp_timer_func_t tcp_timer_funcs[TCPT_NTIMERS] = {
173 tcp_timer_rexmt,
174 tcp_timer_persist,
175 tcp_timer_keep,
176 tcp_timer_2msl,
177 };
178
179 /*
180 * Timer state initialization, called from tcp_init().
181 */
182 void
tcp_timer_init(void)183 tcp_timer_init(void)
184 {
185
186 if (tcp_keepinit == 0)
187 tcp_keepinit = TCPTV_KEEP_INIT;
188
189 if (tcp_keepidle == 0)
190 tcp_keepidle = TCPTV_KEEP_IDLE;
191
192 if (tcp_keepintvl == 0)
193 tcp_keepintvl = TCPTV_KEEPINTVL;
194
195 if (tcp_keepcnt == 0)
196 tcp_keepcnt = TCPTV_KEEPCNT;
197
198 if (tcp_maxpersistidle == 0)
199 tcp_maxpersistidle = TCPTV_KEEP_IDLE;
200
201 if (tcp_delack_ticks == 0)
202 tcp_delack_ticks = TCP_DELACK_TICKS;
203 }
204
205 void
tcp_slowtimo_init(void)206 tcp_slowtimo_init(void)
207 {
208 #ifdef NET_MPSAFE
209 int error;
210
211 error = workqueue_create(&tcp_slowtimo_wq, "tcp_slowtimo",
212 tcp_slowtimo_work, NULL, PRI_SOFTNET, IPL_SOFTNET, WQ_MPSAFE);
213 if (error != 0)
214 panic("%s: workqueue_create failed (%d)\n", __func__, error);
215 #endif
216 callout_init(&tcp_slowtimo_ch, CALLOUT_MPSAFE);
217 callout_reset(&tcp_slowtimo_ch, 1, tcp_slowtimo, NULL);
218 }
219
220 /*
221 * Callout to process delayed ACKs for a TCPCB.
222 */
223 void
tcp_delack(void * arg)224 tcp_delack(void *arg)
225 {
226 struct tcpcb *tp = arg;
227
228 /*
229 * If tcp_output() wasn't able to transmit the ACK
230 * for whatever reason, it will restart the delayed
231 * ACK callout.
232 */
233
234 mutex_enter(softnet_lock);
235 if ((tp->t_flags & (TF_DEAD | TF_DELACK)) != TF_DELACK) {
236 mutex_exit(softnet_lock);
237 return;
238 }
239 if (!callout_expired(&tp->t_delack_ch)) {
240 mutex_exit(softnet_lock);
241 return;
242 }
243
244 tp->t_flags |= TF_ACKNOW;
245 KERNEL_LOCK(1, NULL);
246 (void) tcp_output(tp);
247 KERNEL_UNLOCK_ONE(NULL);
248 mutex_exit(softnet_lock);
249 }
250
251 /*
252 * Tcp protocol timeout routine called every 500 ms.
253 * Updates the timers in all active tcb's and
254 * causes finite state machine actions if timers expire.
255 */
256 static void
tcp_slowtimo_work(struct work * wk,void * arg)257 tcp_slowtimo_work(struct work *wk, void *arg)
258 {
259
260 mutex_enter(softnet_lock);
261 tcp_iss_seq += TCP_ISSINCR + (TCP_ISS_RANDOM_MASK & cprng_fast32());
262 tcp_now++; /* for timestamps */
263 mutex_exit(softnet_lock);
264
265 callout_schedule(&tcp_slowtimo_ch, hz / PR_SLOWHZ);
266 }
267
268 static void
tcp_slowtimo(void * arg)269 tcp_slowtimo(void *arg)
270 {
271
272 #ifdef NET_MPSAFE
273 workqueue_enqueue(tcp_slowtimo_wq, &tcp_slowtimo_wk, NULL);
274 #else
275 tcp_slowtimo_work(NULL, NULL);
276 #endif
277 }
278
279 /*
280 * Cancel all timers for TCP tp.
281 */
282 void
tcp_canceltimers(struct tcpcb * tp)283 tcp_canceltimers(struct tcpcb *tp)
284 {
285 int i;
286
287 for (i = 0; i < TCPT_NTIMERS; i++)
288 TCP_TIMER_DISARM(tp, i);
289 }
290
291 const int tcp_backoff[TCP_MAXRXTSHIFT + 1] =
292 { 1, 2, 4, 8, 16, 32, 64, 64, 64, 64, 64, 64, 64 };
293
294 const int tcp_totbackoff = 511; /* sum of tcp_backoff[] */
295
296 /*
297 * TCP timer processing.
298 */
299
300 void
tcp_timer_rexmt(void * arg)301 tcp_timer_rexmt(void *arg)
302 {
303 struct tcpcb *tp = arg;
304 uint32_t rto;
305 #ifdef TCP_DEBUG
306 struct socket *so = NULL;
307 short ostate;
308 #endif
309
310 mutex_enter(softnet_lock);
311 if ((tp->t_flags & TF_DEAD) != 0) {
312 mutex_exit(softnet_lock);
313 return;
314 }
315 if (!callout_expired(&tp->t_timer[TCPT_REXMT])) {
316 mutex_exit(softnet_lock);
317 return;
318 }
319
320 KERNEL_LOCK(1, NULL);
321 if ((tp->t_flags & TF_PMTUD_PEND) && tp->t_inpcb &&
322 SEQ_GEQ(tp->t_pmtud_th_seq, tp->snd_una) &&
323 SEQ_LT(tp->t_pmtud_th_seq, (int)(tp->snd_una + tp->t_ourmss))) {
324 extern struct sockaddr_in icmpsrc;
325 struct icmp icmp;
326
327 tp->t_flags &= ~TF_PMTUD_PEND;
328
329 /* XXX create fake icmp message with relevant entries */
330 icmp.icmp_nextmtu = tp->t_pmtud_nextmtu;
331 icmp.icmp_ip.ip_len = tp->t_pmtud_ip_len;
332 icmp.icmp_ip.ip_hl = tp->t_pmtud_ip_hl;
333 icmpsrc.sin_addr = in4p_faddr(tp->t_inpcb);
334 icmp_mtudisc(&icmp, icmpsrc.sin_addr);
335
336 /*
337 * Notify all connections to the same peer about
338 * new mss and trigger retransmit.
339 */
340 inpcb_notifyall(&tcbtable, icmpsrc.sin_addr, EMSGSIZE,
341 tcp_mtudisc);
342 KERNEL_UNLOCK_ONE(NULL);
343 mutex_exit(softnet_lock);
344 return;
345 }
346 #ifdef TCP_DEBUG
347 so = tp->t_inpcb->inp_socket;
348 ostate = tp->t_state;
349 #endif /* TCP_DEBUG */
350
351 /*
352 * Clear the SACK scoreboard, reset FACK estimate.
353 */
354 tcp_free_sackholes(tp);
355 tp->snd_fack = tp->snd_una;
356
357 /*
358 * Retransmission timer went off. Message has not
359 * been acked within retransmit interval. Back off
360 * to a longer retransmit interval and retransmit one segment.
361 */
362
363 if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) {
364 tp->t_rxtshift = TCP_MAXRXTSHIFT;
365 TCP_STATINC(TCP_STAT_TIMEOUTDROP);
366 tp = tcp_drop(tp, tp->t_softerror ?
367 tp->t_softerror : ETIMEDOUT);
368 goto out;
369 }
370 TCP_STATINC(TCP_STAT_REXMTTIMEO);
371 rto = TCP_REXMTVAL(tp);
372 if (rto < tp->t_rttmin)
373 rto = tp->t_rttmin;
374 TCPT_RANGESET(tp->t_rxtcur, rto * tcp_backoff[tp->t_rxtshift],
375 tp->t_rttmin, TCPTV_REXMTMAX);
376 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur);
377
378 /*
379 * If we are losing and we are trying path MTU discovery,
380 * try turning it off. This will avoid black holes in
381 * the network which suppress or fail to send "packet
382 * too big" ICMP messages. We should ideally do
383 * lots more sophisticated searching to find the right
384 * value here...
385 */
386 if (tp->t_mtudisc && tp->t_rxtshift > TCP_MAXRXTSHIFT / 6) {
387 TCP_STATINC(TCP_STAT_PMTUBLACKHOLE);
388
389 /* try turning PMTUD off or try using IPv6 minimum MTU */
390 tp->t_mtudisc = 0;
391
392 /* XXX: more sophisticated Black hole recovery code? */
393 }
394
395 /*
396 * If losing, let the lower level know and try for
397 * a better route. Also, if we backed off this far,
398 * our srtt estimate is probably bogus. Clobber it
399 * so we'll take the next rtt measurement as our srtt;
400 * move the current srtt into rttvar to keep the current
401 * retransmit times until then.
402 */
403 if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) {
404 inpcb_losing(tp->t_inpcb);
405 /*
406 * This operation is not described in RFC2988. The
407 * point is to keep srtt+4*rttvar constant, so we
408 * should shift right 2 bits to divide by 4, and then
409 * shift right one bit because the storage
410 * representation of rttvar is 1/16s vs 1/32s for
411 * srtt.
412 */
413 tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT);
414 tp->t_srtt = 0;
415 }
416 tp->snd_nxt = tp->snd_una;
417 tp->snd_high = tp->snd_max;
418 /*
419 * If timing a segment in this window, stop the timer.
420 */
421 tp->t_rtttime = 0;
422 /*
423 * Remember if we are retransmitting a SYN, because if
424 * we do, set the initial congestion window must be set
425 * to 1 segment.
426 */
427 if (tp->t_state == TCPS_SYN_SENT)
428 tp->t_flags |= TF_SYN_REXMT;
429
430 /*
431 * Adjust congestion control parameters.
432 */
433 tp->t_congctl->slow_retransmit(tp);
434
435 (void) tcp_output(tp);
436
437 out:
438 #ifdef TCP_DEBUG
439 if (tp && so->so_options & SO_DEBUG)
440 tcp_trace(TA_USER, ostate, tp, NULL,
441 PRU_SLOWTIMO | (TCPT_REXMT << 8));
442 #endif
443 KERNEL_UNLOCK_ONE(NULL);
444 mutex_exit(softnet_lock);
445 }
446
447 void
tcp_timer_persist(void * arg)448 tcp_timer_persist(void *arg)
449 {
450 struct tcpcb *tp = arg;
451 uint32_t rto;
452 #ifdef TCP_DEBUG
453 struct socket *so = NULL;
454 short ostate;
455 #endif
456
457 mutex_enter(softnet_lock);
458 if ((tp->t_flags & TF_DEAD) != 0) {
459 mutex_exit(softnet_lock);
460 return;
461 }
462 if (!callout_expired(&tp->t_timer[TCPT_PERSIST])) {
463 mutex_exit(softnet_lock);
464 return;
465 }
466
467 KERNEL_LOCK(1, NULL);
468 #ifdef TCP_DEBUG
469 so = tp->t_inpcb->inp_socket;
470 ostate = tp->t_state;
471 #endif /* TCP_DEBUG */
472
473 /*
474 * Persistance timer into zero window.
475 * Force a byte to be output, if possible.
476 */
477
478 /*
479 * Hack: if the peer is dead/unreachable, we do not
480 * time out if the window is closed. After a full
481 * backoff, drop the connection if the idle time
482 * (no responses to probes) reaches the maximum
483 * backoff that we would use if retransmitting.
484 */
485 rto = TCP_REXMTVAL(tp);
486 if (rto < tp->t_rttmin)
487 rto = tp->t_rttmin;
488 if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
489 ((tcp_now - tp->t_rcvtime) >= tcp_maxpersistidle ||
490 (tcp_now - tp->t_rcvtime) >= rto * tcp_totbackoff)) {
491 TCP_STATINC(TCP_STAT_PERSISTDROPS);
492 tp = tcp_drop(tp, ETIMEDOUT);
493 goto out;
494 }
495 TCP_STATINC(TCP_STAT_PERSISTTIMEO);
496 tcp_setpersist(tp);
497 tp->t_force = 1;
498 (void) tcp_output(tp);
499 tp->t_force = 0;
500
501 out:
502 #ifdef TCP_DEBUG
503 if (tp && so->so_options & SO_DEBUG)
504 tcp_trace(TA_USER, ostate, tp, NULL,
505 PRU_SLOWTIMO | (TCPT_PERSIST << 8));
506 #endif
507 KERNEL_UNLOCK_ONE(NULL);
508 mutex_exit(softnet_lock);
509 }
510
511 void
tcp_timer_keep(void * arg)512 tcp_timer_keep(void *arg)
513 {
514 struct tcpcb *tp = arg;
515 struct socket *so = NULL; /* Quell compiler warning */
516 #ifdef TCP_DEBUG
517 short ostate;
518 #endif
519
520 mutex_enter(softnet_lock);
521 if ((tp->t_flags & TF_DEAD) != 0) {
522 mutex_exit(softnet_lock);
523 return;
524 }
525 if (!callout_expired(&tp->t_timer[TCPT_KEEP])) {
526 mutex_exit(softnet_lock);
527 return;
528 }
529
530 KERNEL_LOCK(1, NULL);
531
532 #ifdef TCP_DEBUG
533 ostate = tp->t_state;
534 #endif /* TCP_DEBUG */
535
536 /*
537 * Keep-alive timer went off; send something
538 * or drop connection if idle for too long.
539 */
540
541 TCP_STATINC(TCP_STAT_KEEPTIMEO);
542 if (TCPS_HAVEESTABLISHED(tp->t_state) == 0)
543 goto dropit;
544 so = tp->t_inpcb->inp_socket;
545 KASSERT(so != NULL);
546 if (so->so_options & SO_KEEPALIVE &&
547 tp->t_state <= TCPS_CLOSE_WAIT) {
548 if ((tp->t_maxidle > 0) &&
549 ((tcp_now - tp->t_rcvtime) >=
550 tp->t_keepidle + tp->t_maxidle))
551 goto dropit;
552 /*
553 * Send a packet designed to force a response
554 * if the peer is up and reachable:
555 * either an ACK if the connection is still alive,
556 * or an RST if the peer has closed the connection
557 * due to timeout or reboot.
558 * Using sequence number tp->snd_una-1
559 * causes the transmitted zero-length segment
560 * to lie outside the receive window;
561 * by the protocol spec, this requires the
562 * correspondent TCP to respond.
563 */
564 TCP_STATINC(TCP_STAT_KEEPPROBE);
565
566 (void)tcp_respond(tp, tp->t_template,
567 NULL, NULL, tp->rcv_nxt,
568 tp->snd_una - 1, 0);
569
570 TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepintvl);
571 } else
572 TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepidle);
573
574 #ifdef TCP_DEBUG
575 if (tp && so->so_options & SO_DEBUG)
576 tcp_trace(TA_USER, ostate, tp, NULL,
577 PRU_SLOWTIMO | (TCPT_KEEP << 8));
578 #endif
579 KERNEL_UNLOCK_ONE(NULL);
580 mutex_exit(softnet_lock);
581 return;
582
583 dropit:
584 TCP_STATINC(TCP_STAT_KEEPDROPS);
585 (void) tcp_drop(tp, ETIMEDOUT);
586 KERNEL_UNLOCK_ONE(NULL);
587 mutex_exit(softnet_lock);
588 }
589
590 void
tcp_timer_2msl(void * arg)591 tcp_timer_2msl(void *arg)
592 {
593 struct tcpcb *tp = arg;
594 #ifdef TCP_DEBUG
595 struct socket *so = NULL;
596 short ostate;
597 #endif
598
599 mutex_enter(softnet_lock);
600 if ((tp->t_flags & TF_DEAD) != 0) {
601 mutex_exit(softnet_lock);
602 return;
603 }
604 if (!callout_expired(&tp->t_timer[TCPT_2MSL])) {
605 mutex_exit(softnet_lock);
606 return;
607 }
608
609 /*
610 * 2 MSL timeout went off, clear the SACK scoreboard, reset
611 * the FACK estimate.
612 */
613 KERNEL_LOCK(1, NULL);
614 tcp_free_sackholes(tp);
615 tp->snd_fack = tp->snd_una;
616
617 #ifdef TCP_DEBUG
618 so = tp->t_inpcb->inp_socket;
619 ostate = tp->t_state;
620 #endif /* TCP_DEBUG */
621
622 /*
623 * 2 MSL timeout in shutdown went off. If we're closed but
624 * still waiting for peer to close and connection has been idle
625 * too long, or if 2MSL time is up from TIME_WAIT, delete connection
626 * control block. Otherwise, check again in a bit.
627 */
628 if (tp->t_state != TCPS_TIME_WAIT &&
629 ((tp->t_maxidle == 0) ||
630 ((tcp_now - tp->t_rcvtime) <= tp->t_maxidle)))
631 TCP_TIMER_ARM(tp, TCPT_2MSL, tp->t_keepintvl);
632 else
633 tp = tcp_close(tp);
634
635 #ifdef TCP_DEBUG
636 if (tp && so->so_options & SO_DEBUG)
637 tcp_trace(TA_USER, ostate, tp, NULL,
638 PRU_SLOWTIMO | (TCPT_2MSL << 8));
639 #endif
640 KERNEL_UNLOCK_ONE(NULL);
641 mutex_exit(softnet_lock);
642 }
643