1 /*-
2 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 4. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * @(#)tcp_timer.c 8.2 (Berkeley) 5/24/95
30 */
31
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD: releng/9.2/sys/netinet/tcp_timer.c 252794 2013-07-05 15:57:36Z andre $");
34
35 #include "opt_inet.h"
36 #include "opt_inet6.h"
37 #include "opt_tcpdebug.h"
38
39 #include <sys/param.h>
40 #include <sys/kernel.h>
41 #include <sys/lock.h>
42 #include <sys/mbuf.h>
43 #include <sys/mutex.h>
44 #include <sys/protosw.h>
45 #include <sys/smp.h>
46 #include <sys/socket.h>
47 #include <sys/socketvar.h>
48 #include <sys/sysctl.h>
49 #include <sys/systm.h>
50
51 #include <net/if.h>
52 #include <net/route.h>
53 #include <net/vnet.h>
54
55 #include <netinet/cc.h>
56 #include <netinet/in.h>
57 #include <netinet/in_pcb.h>
58 #include <netinet/in_systm.h>
59 #ifdef INET6
60 #include <netinet6/in6_pcb.h>
61 #endif
62 #include <netinet/ip_var.h>
63 #include <netinet/tcp_fsm.h>
64 #include <netinet/tcp_timer.h>
65 #include <netinet/tcp_var.h>
66 #include <netinet/tcpip.h>
67 #ifdef TCPDEBUG
68 #include <netinet/tcp_debug.h>
69 #endif
70
71 int tcp_keepinit;
72 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit, CTLTYPE_INT|CTLFLAG_RW,
73 &tcp_keepinit, 0, sysctl_msec_to_ticks, "I", "time to establish connection");
74
75 int tcp_keepidle;
76 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle, CTLTYPE_INT|CTLFLAG_RW,
77 &tcp_keepidle, 0, sysctl_msec_to_ticks, "I", "time before keepalive probes begin");
78
79 int tcp_keepintvl;
80 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl, CTLTYPE_INT|CTLFLAG_RW,
81 &tcp_keepintvl, 0, sysctl_msec_to_ticks, "I", "time between keepalive probes");
82
83 int tcp_delacktime;
84 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DELACKTIME, delacktime, CTLTYPE_INT|CTLFLAG_RW,
85 &tcp_delacktime, 0, sysctl_msec_to_ticks, "I",
86 "Time before a delayed ACK is sent");
87
88 int tcp_msl;
89 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl, CTLTYPE_INT|CTLFLAG_RW,
90 &tcp_msl, 0, sysctl_msec_to_ticks, "I", "Maximum segment lifetime");
91
92 int tcp_rexmit_min;
93 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_min, CTLTYPE_INT|CTLFLAG_RW,
94 &tcp_rexmit_min, 0, sysctl_msec_to_ticks, "I",
95 "Minimum Retransmission Timeout");
96
97 int tcp_rexmit_slop;
98 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_slop, CTLTYPE_INT|CTLFLAG_RW,
99 &tcp_rexmit_slop, 0, sysctl_msec_to_ticks, "I",
100 "Retransmission Timer Slop");
101
102 static int always_keepalive = 1;
103 SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive, CTLFLAG_RW,
104 &always_keepalive , 0, "Assume SO_KEEPALIVE on all TCP connections");
105
106 int tcp_fast_finwait2_recycle = 0;
107 SYSCTL_INT(_net_inet_tcp, OID_AUTO, fast_finwait2_recycle, CTLFLAG_RW,
108 &tcp_fast_finwait2_recycle, 0,
109 "Recycle closed FIN_WAIT_2 connections faster");
110
111 int tcp_finwait2_timeout;
112 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, finwait2_timeout, CTLTYPE_INT|CTLFLAG_RW,
113 &tcp_finwait2_timeout, 0, sysctl_msec_to_ticks, "I", "FIN-WAIT2 timeout");
114
115 int tcp_keepcnt = TCPTV_KEEPCNT;
116 SYSCTL_INT(_net_inet_tcp, OID_AUTO, keepcnt, CTLFLAG_RW, &tcp_keepcnt, 0,
117 "Number of keepalive probes to send");
118
119 /* max idle probes */
120 int tcp_maxpersistidle;
121
122 static int tcp_rexmit_drop_options = 1;
123 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rexmit_drop_options, CTLFLAG_RW,
124 &tcp_rexmit_drop_options, 0,
125 "Drop TCP options from 3rd and later retransmitted SYN");
126
127 static int per_cpu_timers = 0;
128 SYSCTL_INT(_net_inet_tcp, OID_AUTO, per_cpu_timers, CTLFLAG_RW,
129 &per_cpu_timers , 0, "run tcp timers on all cpus");
130
131 #define INP_CPU(inp) (per_cpu_timers ? (!CPU_ABSENT(((inp)->inp_flowid % (mp_maxid+1))) ? \
132 ((inp)->inp_flowid % (mp_maxid+1)) : curcpu) : 0)
133
134 /*
135 * Tcp protocol timeout routine called every 500 ms.
136 * Updates timestamps used for TCP
137 * causes finite state machine actions if timers expire.
138 */
139 void
140 tcp_slowtimo(void)
141 {
142 VNET_ITERATOR_DECL(vnet_iter);
143
144 VNET_LIST_RLOCK_NOSLEEP();
145 VNET_FOREACH(vnet_iter) {
146 CURVNET_SET(vnet_iter);
147 INP_INFO_WLOCK(&V_tcbinfo);
148 (void) tcp_tw_2msl_scan(0);
149 INP_INFO_WUNLOCK(&V_tcbinfo);
150 CURVNET_RESTORE();
151 }
152 VNET_LIST_RUNLOCK_NOSLEEP();
153 }
154
155 int tcp_syn_backoff[TCP_MAXRXTSHIFT + 1] =
156 { 1, 1, 1, 1, 1, 2, 4, 8, 16, 32, 64, 64, 64 };
157
158 int tcp_backoff[TCP_MAXRXTSHIFT + 1] =
159 { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 512, 512, 512 };
160
161 static int tcp_totbackoff = 2559; /* sum of tcp_backoff[] */
162
163 static int tcp_timer_race;
164 SYSCTL_INT(_net_inet_tcp, OID_AUTO, timer_race, CTLFLAG_RD, &tcp_timer_race,
165 0, "Count of t_inpcb races on tcp_discardcb");
166
167 /*
168 * TCP timer processing.
169 */
170
171 void
172 tcp_timer_delack(void *xtp)
173 {
174 struct tcpcb *tp = xtp;
175 struct inpcb *inp;
176 CURVNET_SET(tp->t_vnet);
177
178 inp = tp->t_inpcb;
179 /*
180 * XXXRW: While this assert is in fact correct, bugs in the tcpcb
181 * tear-down mean we need it as a work-around for races between
182 * timers and tcp_discardcb().
183 *
184 * KASSERT(inp != NULL, ("tcp_timer_delack: inp == NULL"));
185 */
186 if (inp == NULL) {
187 tcp_timer_race++;
188 CURVNET_RESTORE();
189 return;
190 }
191 INP_WLOCK(inp);
192 if (callout_pending(&tp->t_timers->tt_delack) ||
193 !callout_active(&tp->t_timers->tt_delack)) {
194 INP_WUNLOCK(inp);
195 CURVNET_RESTORE();
196 return;
197 }
198 callout_deactivate(&tp->t_timers->tt_delack);
199 if ((inp->inp_flags & INP_DROPPED) != 0) {
200 INP_WUNLOCK(inp);
201 CURVNET_RESTORE();
202 return;
203 }
204
205 tp->t_flags |= TF_ACKNOW;
206 TCPSTAT_INC(tcps_delack);
207 (void) tcp_output(tp);
208 INP_WUNLOCK(inp);
209 CURVNET_RESTORE();
210 }
211
212 void
213 tcp_timer_2msl(void *xtp)
214 {
215 struct tcpcb *tp = xtp;
216 struct inpcb *inp;
217 CURVNET_SET(tp->t_vnet);
218 #ifdef TCPDEBUG
219 int ostate;
220
221 ostate = tp->t_state;
222 #endif
223 /*
224 * XXXRW: Does this actually happen?
225 */
226 INP_INFO_WLOCK(&V_tcbinfo);
227 inp = tp->t_inpcb;
228 /*
229 * XXXRW: While this assert is in fact correct, bugs in the tcpcb
230 * tear-down mean we need it as a work-around for races between
231 * timers and tcp_discardcb().
232 *
233 * KASSERT(inp != NULL, ("tcp_timer_2msl: inp == NULL"));
234 */
235 if (inp == NULL) {
236 tcp_timer_race++;
237 INP_INFO_WUNLOCK(&V_tcbinfo);
238 CURVNET_RESTORE();
239 return;
240 }
241 INP_WLOCK(inp);
242 tcp_free_sackholes(tp);
243 if (callout_pending(&tp->t_timers->tt_2msl) ||
244 !callout_active(&tp->t_timers->tt_2msl)) {
245 INP_WUNLOCK(tp->t_inpcb);
246 INP_INFO_WUNLOCK(&V_tcbinfo);
247 CURVNET_RESTORE();
248 return;
249 }
250 callout_deactivate(&tp->t_timers->tt_2msl);
251 if ((inp->inp_flags & INP_DROPPED) != 0) {
252 INP_WUNLOCK(inp);
253 INP_INFO_WUNLOCK(&V_tcbinfo);
254 CURVNET_RESTORE();
255 return;
256 }
257 /*
258 * 2 MSL timeout in shutdown went off. If we're closed but
259 * still waiting for peer to close and connection has been idle
260 * too long, or if 2MSL time is up from TIME_WAIT, delete connection
261 * control block. Otherwise, check again in a bit.
262 *
263 * If fastrecycle of FIN_WAIT_2, in FIN_WAIT_2 and receiver has closed,
264 * there's no point in hanging onto FIN_WAIT_2 socket. Just close it.
265 * Ignore fact that there were recent incoming segments.
266 */
267 if (tcp_fast_finwait2_recycle && tp->t_state == TCPS_FIN_WAIT_2 &&
268 tp->t_inpcb && tp->t_inpcb->inp_socket &&
269 (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE)) {
270 TCPSTAT_INC(tcps_finwait2_drops);
271 tp = tcp_close(tp);
272 } else {
273 if (tp->t_state != TCPS_TIME_WAIT &&
274 ticks - tp->t_rcvtime <= TP_MAXIDLE(tp))
275 callout_reset_on(&tp->t_timers->tt_2msl,
276 TP_KEEPINTVL(tp), tcp_timer_2msl, tp, INP_CPU(inp));
277 else
278 tp = tcp_close(tp);
279 }
280
281 #ifdef TCPDEBUG
282 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
283 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
284 PRU_SLOWTIMO);
285 #endif
286 if (tp != NULL)
287 INP_WUNLOCK(inp);
288 INP_INFO_WUNLOCK(&V_tcbinfo);
289 CURVNET_RESTORE();
290 }
291
292 void
293 tcp_timer_keep(void *xtp)
294 {
295 struct tcpcb *tp = xtp;
296 struct tcptemp *t_template;
297 struct inpcb *inp;
298 CURVNET_SET(tp->t_vnet);
299 #ifdef TCPDEBUG
300 int ostate;
301
302 ostate = tp->t_state;
303 #endif
304 INP_INFO_WLOCK(&V_tcbinfo);
305 inp = tp->t_inpcb;
306 /*
307 * XXXRW: While this assert is in fact correct, bugs in the tcpcb
308 * tear-down mean we need it as a work-around for races between
309 * timers and tcp_discardcb().
310 *
311 * KASSERT(inp != NULL, ("tcp_timer_keep: inp == NULL"));
312 */
313 if (inp == NULL) {
314 tcp_timer_race++;
315 INP_INFO_WUNLOCK(&V_tcbinfo);
316 CURVNET_RESTORE();
317 return;
318 }
319 INP_WLOCK(inp);
320 if (callout_pending(&tp->t_timers->tt_keep) ||
321 !callout_active(&tp->t_timers->tt_keep)) {
322 INP_WUNLOCK(inp);
323 INP_INFO_WUNLOCK(&V_tcbinfo);
324 CURVNET_RESTORE();
325 return;
326 }
327 callout_deactivate(&tp->t_timers->tt_keep);
328 if ((inp->inp_flags & INP_DROPPED) != 0) {
329 INP_WUNLOCK(inp);
330 INP_INFO_WUNLOCK(&V_tcbinfo);
331 CURVNET_RESTORE();
332 return;
333 }
334 /*
335 * Keep-alive timer went off; send something
336 * or drop connection if idle for too long.
337 */
338 TCPSTAT_INC(tcps_keeptimeo);
339 if (tp->t_state < TCPS_ESTABLISHED)
340 goto dropit;
341 if ((always_keepalive || inp->inp_socket->so_options & SO_KEEPALIVE) &&
342 tp->t_state <= TCPS_CLOSING) {
343 if (ticks - tp->t_rcvtime >= TP_KEEPIDLE(tp) + TP_MAXIDLE(tp))
344 goto dropit;
345 /*
346 * Send a packet designed to force a response
347 * if the peer is up and reachable:
348 * either an ACK if the connection is still alive,
349 * or an RST if the peer has closed the connection
350 * due to timeout or reboot.
351 * Using sequence number tp->snd_una-1
352 * causes the transmitted zero-length segment
353 * to lie outside the receive window;
354 * by the protocol spec, this requires the
355 * correspondent TCP to respond.
356 */
357 TCPSTAT_INC(tcps_keepprobe);
358 t_template = tcpip_maketemplate(inp);
359 if (t_template) {
360 tcp_respond(tp, t_template->tt_ipgen,
361 &t_template->tt_t, (struct mbuf *)NULL,
362 tp->rcv_nxt, tp->snd_una - 1, 0);
363 free(t_template, M_TEMP);
364 }
365 callout_reset_on(&tp->t_timers->tt_keep, TP_KEEPINTVL(tp),
366 tcp_timer_keep, tp, INP_CPU(inp));
367 } else
368 callout_reset_on(&tp->t_timers->tt_keep, TP_KEEPIDLE(tp),
369 tcp_timer_keep, tp, INP_CPU(inp));
370
371 #ifdef TCPDEBUG
372 if (inp->inp_socket->so_options & SO_DEBUG)
373 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
374 PRU_SLOWTIMO);
375 #endif
376 INP_WUNLOCK(inp);
377 INP_INFO_WUNLOCK(&V_tcbinfo);
378 CURVNET_RESTORE();
379 return;
380
381 dropit:
382 TCPSTAT_INC(tcps_keepdrops);
383 tp = tcp_drop(tp, ETIMEDOUT);
384
385 #ifdef TCPDEBUG
386 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
387 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
388 PRU_SLOWTIMO);
389 #endif
390 if (tp != NULL)
391 INP_WUNLOCK(tp->t_inpcb);
392 INP_INFO_WUNLOCK(&V_tcbinfo);
393 CURVNET_RESTORE();
394 }
395
396 void
397 tcp_timer_persist(void *xtp)
398 {
399 struct tcpcb *tp = xtp;
400 struct inpcb *inp;
401 CURVNET_SET(tp->t_vnet);
402 #ifdef TCPDEBUG
403 int ostate;
404
405 ostate = tp->t_state;
406 #endif
407 INP_INFO_WLOCK(&V_tcbinfo);
408 inp = tp->t_inpcb;
409 /*
410 * XXXRW: While this assert is in fact correct, bugs in the tcpcb
411 * tear-down mean we need it as a work-around for races between
412 * timers and tcp_discardcb().
413 *
414 * KASSERT(inp != NULL, ("tcp_timer_persist: inp == NULL"));
415 */
416 if (inp == NULL) {
417 tcp_timer_race++;
418 INP_INFO_WUNLOCK(&V_tcbinfo);
419 CURVNET_RESTORE();
420 return;
421 }
422 INP_WLOCK(inp);
423 if (callout_pending(&tp->t_timers->tt_persist) ||
424 !callout_active(&tp->t_timers->tt_persist)) {
425 INP_WUNLOCK(inp);
426 INP_INFO_WUNLOCK(&V_tcbinfo);
427 CURVNET_RESTORE();
428 return;
429 }
430 callout_deactivate(&tp->t_timers->tt_persist);
431 if ((inp->inp_flags & INP_DROPPED) != 0) {
432 INP_WUNLOCK(inp);
433 INP_INFO_WUNLOCK(&V_tcbinfo);
434 CURVNET_RESTORE();
435 return;
436 }
437 /*
438 * Persistance timer into zero window.
439 * Force a byte to be output, if possible.
440 */
441 TCPSTAT_INC(tcps_persisttimeo);
442 /*
443 * Hack: if the peer is dead/unreachable, we do not
444 * time out if the window is closed. After a full
445 * backoff, drop the connection if the idle time
446 * (no responses to probes) reaches the maximum
447 * backoff that we would use if retransmitting.
448 */
449 if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
450 (ticks - tp->t_rcvtime >= tcp_maxpersistidle ||
451 ticks - tp->t_rcvtime >= TCP_REXMTVAL(tp) * tcp_totbackoff)) {
452 TCPSTAT_INC(tcps_persistdrop);
453 tp = tcp_drop(tp, ETIMEDOUT);
454 goto out;
455 }
456 /*
457 * If the user has closed the socket then drop a persisting
458 * connection after a much reduced timeout.
459 */
460 if (tp->t_state > TCPS_CLOSE_WAIT &&
461 (ticks - tp->t_rcvtime) >= TCPTV_PERSMAX) {
462 TCPSTAT_INC(tcps_persistdrop);
463 tp = tcp_drop(tp, ETIMEDOUT);
464 goto out;
465 }
466 tcp_setpersist(tp);
467 tp->t_flags |= TF_FORCEDATA;
468 (void) tcp_output(tp);
469 tp->t_flags &= ~TF_FORCEDATA;
470
471 out:
472 #ifdef TCPDEBUG
473 if (tp != NULL && tp->t_inpcb->inp_socket->so_options & SO_DEBUG)
474 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO);
475 #endif
476 if (tp != NULL)
477 INP_WUNLOCK(inp);
478 INP_INFO_WUNLOCK(&V_tcbinfo);
479 CURVNET_RESTORE();
480 }
481
482 void
483 tcp_timer_rexmt(void * xtp)
484 {
485 struct tcpcb *tp = xtp;
486 CURVNET_SET(tp->t_vnet);
487 int rexmt;
488 int headlocked;
489 struct inpcb *inp;
490 #ifdef TCPDEBUG
491 int ostate;
492
493 ostate = tp->t_state;
494 #endif
495 INP_INFO_RLOCK(&V_tcbinfo);
496 inp = tp->t_inpcb;
497 /*
498 * XXXRW: While this assert is in fact correct, bugs in the tcpcb
499 * tear-down mean we need it as a work-around for races between
500 * timers and tcp_discardcb().
501 *
502 * KASSERT(inp != NULL, ("tcp_timer_rexmt: inp == NULL"));
503 */
504 if (inp == NULL) {
505 tcp_timer_race++;
506 INP_INFO_RUNLOCK(&V_tcbinfo);
507 CURVNET_RESTORE();
508 return;
509 }
510 INP_WLOCK(inp);
511 if (callout_pending(&tp->t_timers->tt_rexmt) ||
512 !callout_active(&tp->t_timers->tt_rexmt)) {
513 INP_WUNLOCK(inp);
514 INP_INFO_RUNLOCK(&V_tcbinfo);
515 CURVNET_RESTORE();
516 return;
517 }
518 callout_deactivate(&tp->t_timers->tt_rexmt);
519 if ((inp->inp_flags & INP_DROPPED) != 0) {
520 INP_WUNLOCK(inp);
521 INP_INFO_RUNLOCK(&V_tcbinfo);
522 CURVNET_RESTORE();
523 return;
524 }
525 tcp_free_sackholes(tp);
526 /*
527 * Retransmission timer went off. Message has not
528 * been acked within retransmit interval. Back off
529 * to a longer retransmit interval and retransmit one segment.
530 */
531 if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) {
532 tp->t_rxtshift = TCP_MAXRXTSHIFT;
533 TCPSTAT_INC(tcps_timeoutdrop);
534 in_pcbref(inp);
535 INP_INFO_RUNLOCK(&V_tcbinfo);
536 INP_WUNLOCK(inp);
537 INP_INFO_WLOCK(&V_tcbinfo);
538 INP_WLOCK(inp);
539 if (in_pcbrele_wlocked(inp)) {
540 INP_INFO_WUNLOCK(&V_tcbinfo);
541 CURVNET_RESTORE();
542 return;
543 }
544 if (inp->inp_flags & INP_DROPPED) {
545 INP_WUNLOCK(inp);
546 INP_INFO_WUNLOCK(&V_tcbinfo);
547 CURVNET_RESTORE();
548 return;
549 }
550
551 tp = tcp_drop(tp, tp->t_softerror ?
552 tp->t_softerror : ETIMEDOUT);
553 headlocked = 1;
554 goto out;
555 }
556 INP_INFO_RUNLOCK(&V_tcbinfo);
557 headlocked = 0;
558 if (tp->t_state == TCPS_SYN_SENT) {
559 /*
560 * If the SYN was retransmitted, indicate CWND to be
561 * limited to 1 segment in cc_conn_init().
562 */
563 tp->snd_cwnd = 1;
564 } else if (tp->t_rxtshift == 1) {
565 /*
566 * first retransmit; record ssthresh and cwnd so they can
567 * be recovered if this turns out to be a "bad" retransmit.
568 * A retransmit is considered "bad" if an ACK for this
569 * segment is received within RTT/2 interval; the assumption
570 * here is that the ACK was already in flight. See
571 * "On Estimating End-to-End Network Path Properties" by
572 * Allman and Paxson for more details.
573 */
574 tp->snd_cwnd_prev = tp->snd_cwnd;
575 tp->snd_ssthresh_prev = tp->snd_ssthresh;
576 tp->snd_recover_prev = tp->snd_recover;
577 if (IN_FASTRECOVERY(tp->t_flags))
578 tp->t_flags |= TF_WASFRECOVERY;
579 else
580 tp->t_flags &= ~TF_WASFRECOVERY;
581 if (IN_CONGRECOVERY(tp->t_flags))
582 tp->t_flags |= TF_WASCRECOVERY;
583 else
584 tp->t_flags &= ~TF_WASCRECOVERY;
585 tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1));
586 tp->t_flags |= TF_PREVVALID;
587 } else
588 tp->t_flags &= ~TF_PREVVALID;
589 TCPSTAT_INC(tcps_rexmttimeo);
590 if (tp->t_state == TCPS_SYN_SENT)
591 rexmt = TCPTV_RTOBASE * tcp_syn_backoff[tp->t_rxtshift];
592 else
593 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
594 TCPT_RANGESET(tp->t_rxtcur, rexmt,
595 tp->t_rttmin, TCPTV_REXMTMAX);
596 /*
597 * Disable RFC1323 and SACK if we haven't got any response to
598 * our third SYN to work-around some broken terminal servers
599 * (most of which have hopefully been retired) that have bad VJ
600 * header compression code which trashes TCP segments containing
601 * unknown-to-them TCP options.
602 */
603 if (tcp_rexmit_drop_options && (tp->t_state == TCPS_SYN_SENT) &&
604 (tp->t_rxtshift == 3))
605 tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP|TF_SACK_PERMIT);
606 /*
607 * If we backed off this far, our srtt estimate is probably bogus.
608 * Clobber it so we'll take the next rtt measurement as our srtt;
609 * move the current srtt into rttvar to keep the current
610 * retransmit times until then.
611 */
612 if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) {
613 #ifdef INET6
614 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0)
615 in6_losing(tp->t_inpcb);
616 #endif
617 tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT);
618 tp->t_srtt = 0;
619 }
620 tp->snd_nxt = tp->snd_una;
621 tp->snd_recover = tp->snd_max;
622 /*
623 * Force a segment to be sent.
624 */
625 tp->t_flags |= TF_ACKNOW;
626 /*
627 * If timing a segment in this window, stop the timer.
628 */
629 tp->t_rtttime = 0;
630
631 cc_cong_signal(tp, NULL, CC_RTO);
632
633 (void) tcp_output(tp);
634
635 out:
636 #ifdef TCPDEBUG
637 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
638 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
639 PRU_SLOWTIMO);
640 #endif
641 if (tp != NULL)
642 INP_WUNLOCK(inp);
643 if (headlocked)
644 INP_INFO_WUNLOCK(&V_tcbinfo);
645 CURVNET_RESTORE();
646 }
647
648 void
649 tcp_timer_activate(struct tcpcb *tp, int timer_type, u_int delta)
650 {
651 struct callout *t_callout;
652 void *f_callout;
653 struct inpcb *inp = tp->t_inpcb;
654 int cpu = INP_CPU(inp);
655
656 #ifdef TCP_OFFLOAD
657 if (tp->t_flags & TF_TOE)
658 return;
659 #endif
660
661 switch (timer_type) {
662 case TT_DELACK:
663 t_callout = &tp->t_timers->tt_delack;
664 f_callout = tcp_timer_delack;
665 break;
666 case TT_REXMT:
667 t_callout = &tp->t_timers->tt_rexmt;
668 f_callout = tcp_timer_rexmt;
669 break;
670 case TT_PERSIST:
671 t_callout = &tp->t_timers->tt_persist;
672 f_callout = tcp_timer_persist;
673 break;
674 case TT_KEEP:
675 t_callout = &tp->t_timers->tt_keep;
676 f_callout = tcp_timer_keep;
677 break;
678 case TT_2MSL:
679 t_callout = &tp->t_timers->tt_2msl;
680 f_callout = tcp_timer_2msl;
681 break;
682 default:
683 panic("bad timer_type");
684 }
685 if (delta == 0) {
686 callout_stop(t_callout);
687 } else {
688 callout_reset_on(t_callout, delta, f_callout, tp, cpu);
689 }
690 }
691
692 int
693 tcp_timer_active(struct tcpcb *tp, int timer_type)
694 {
695 struct callout *t_callout;
696
697 switch (timer_type) {
698 case TT_DELACK:
699 t_callout = &tp->t_timers->tt_delack;
700 break;
701 case TT_REXMT:
702 t_callout = &tp->t_timers->tt_rexmt;
703 break;
704 case TT_PERSIST:
705 t_callout = &tp->t_timers->tt_persist;
706 break;
707 case TT_KEEP:
708 t_callout = &tp->t_timers->tt_keep;
709 break;
710 case TT_2MSL:
711 t_callout = &tp->t_timers->tt_2msl;
712 break;
713 default:
714 panic("bad timer_type");
715 }
716 return callout_active(t_callout);
717 }
718
719 #define ticks_to_msecs(t) (1000*(t) / hz)
720
721 void
722 tcp_timer_to_xtimer(struct tcpcb *tp, struct tcp_timer *timer, struct xtcp_timer *xtimer)
723 {
724 bzero(xtimer, sizeof(struct xtcp_timer));
725 if (timer == NULL)
726 return;
727 if (callout_active(&timer->tt_delack))
728 xtimer->tt_delack = ticks_to_msecs(timer->tt_delack.c_time - ticks);
729 if (callout_active(&timer->tt_rexmt))
730 xtimer->tt_rexmt = ticks_to_msecs(timer->tt_rexmt.c_time - ticks);
731 if (callout_active(&timer->tt_persist))
732 xtimer->tt_persist = ticks_to_msecs(timer->tt_persist.c_time - ticks);
733 if (callout_active(&timer->tt_keep))
734 xtimer->tt_keep = ticks_to_msecs(timer->tt_keep.c_time - ticks);
735 if (callout_active(&timer->tt_2msl))
736 xtimer->tt_2msl = ticks_to_msecs(timer->tt_2msl.c_time - ticks);
737 xtimer->t_rcvtime = ticks_to_msecs(ticks - tp->t_rcvtime);
738 }
Cache object: 9c21e469173fc00ac825a394fdaac20c
|