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/10.4/sys/netinet/tcp_timer.c 309108 2016-11-24 14:48:46Z jch $");
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 #ifdef INET6
67 #include <netinet6/tcp6_var.h>
68 #endif
69 #include <netinet/tcpip.h>
70 #ifdef TCPDEBUG
71 #include <netinet/tcp_debug.h>
72 #endif
73
74 int tcp_persmin;
75 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, persmin, CTLTYPE_INT|CTLFLAG_RW,
76 &tcp_persmin, 0, sysctl_msec_to_ticks, "I", "minimum persistence interval");
77
78 int tcp_persmax;
79 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, persmax, CTLTYPE_INT|CTLFLAG_RW,
80 &tcp_persmax, 0, sysctl_msec_to_ticks, "I", "maximum persistence interval");
81
82 int tcp_keepinit;
83 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit, CTLTYPE_INT|CTLFLAG_RW,
84 &tcp_keepinit, 0, sysctl_msec_to_ticks, "I", "time to establish connection");
85
86 int tcp_keepidle;
87 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle, CTLTYPE_INT|CTLFLAG_RW,
88 &tcp_keepidle, 0, sysctl_msec_to_ticks, "I", "time before keepalive probes begin");
89
90 int tcp_keepintvl;
91 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl, CTLTYPE_INT|CTLFLAG_RW,
92 &tcp_keepintvl, 0, sysctl_msec_to_ticks, "I", "time between keepalive probes");
93
94 int tcp_delacktime;
95 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DELACKTIME, delacktime, CTLTYPE_INT|CTLFLAG_RW,
96 &tcp_delacktime, 0, sysctl_msec_to_ticks, "I",
97 "Time before a delayed ACK is sent");
98
99 int tcp_msl;
100 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl, CTLTYPE_INT|CTLFLAG_RW,
101 &tcp_msl, 0, sysctl_msec_to_ticks, "I", "Maximum segment lifetime");
102
103 int tcp_rexmit_min;
104 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_min, CTLTYPE_INT|CTLFLAG_RW,
105 &tcp_rexmit_min, 0, sysctl_msec_to_ticks, "I",
106 "Minimum Retransmission Timeout");
107
108 int tcp_rexmit_slop;
109 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_slop, CTLTYPE_INT|CTLFLAG_RW,
110 &tcp_rexmit_slop, 0, sysctl_msec_to_ticks, "I",
111 "Retransmission Timer Slop");
112
113 static int always_keepalive = 1;
114 SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive, CTLFLAG_RW,
115 &always_keepalive , 0, "Assume SO_KEEPALIVE on all TCP connections");
116
117 int tcp_fast_finwait2_recycle = 0;
118 SYSCTL_INT(_net_inet_tcp, OID_AUTO, fast_finwait2_recycle, CTLFLAG_RW,
119 &tcp_fast_finwait2_recycle, 0,
120 "Recycle closed FIN_WAIT_2 connections faster");
121
122 int tcp_finwait2_timeout;
123 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, finwait2_timeout, CTLTYPE_INT|CTLFLAG_RW,
124 &tcp_finwait2_timeout, 0, sysctl_msec_to_ticks, "I", "FIN-WAIT2 timeout");
125
126 int tcp_keepcnt = TCPTV_KEEPCNT;
127 SYSCTL_INT(_net_inet_tcp, OID_AUTO, keepcnt, CTLFLAG_RW, &tcp_keepcnt, 0,
128 "Number of keepalive probes to send");
129
130 /* max idle probes */
131 int tcp_maxpersistidle;
132
133 static int tcp_rexmit_drop_options = 0;
134 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rexmit_drop_options, CTLFLAG_RW,
135 &tcp_rexmit_drop_options, 0,
136 "Drop TCP options from 3rd and later retransmitted SYN");
137
138 static VNET_DEFINE(int, tcp_pmtud_blackhole_detect);
139 #define V_tcp_pmtud_blackhole_detect VNET(tcp_pmtud_blackhole_detect)
140 SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_detection,
141 CTLFLAG_RW,
142 &VNET_NAME(tcp_pmtud_blackhole_detect), 0,
143 "Path MTU Discovery Black Hole Detection Enabled");
144
145 static VNET_DEFINE(int, tcp_pmtud_blackhole_activated);
146 #define V_tcp_pmtud_blackhole_activated \
147 VNET(tcp_pmtud_blackhole_activated)
148 SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_activated,
149 CTLFLAG_RD,
150 &VNET_NAME(tcp_pmtud_blackhole_activated), 0,
151 "Path MTU Discovery Black Hole Detection, Activation Count");
152
153 static VNET_DEFINE(int, tcp_pmtud_blackhole_activated_min_mss);
154 #define V_tcp_pmtud_blackhole_activated_min_mss \
155 VNET(tcp_pmtud_blackhole_activated_min_mss)
156 SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_activated_min_mss,
157 CTLFLAG_RD,
158 &VNET_NAME(tcp_pmtud_blackhole_activated_min_mss), 0,
159 "Path MTU Discovery Black Hole Detection, Activation Count at min MSS");
160
161 static VNET_DEFINE(int, tcp_pmtud_blackhole_failed);
162 #define V_tcp_pmtud_blackhole_failed VNET(tcp_pmtud_blackhole_failed)
163 SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_failed,
164 CTLFLAG_RD,
165 &VNET_NAME(tcp_pmtud_blackhole_failed), 0,
166 "Path MTU Discovery Black Hole Detection, Failure Count");
167
168 #ifdef INET
169 static VNET_DEFINE(int, tcp_pmtud_blackhole_mss) = 1200;
170 #define V_tcp_pmtud_blackhole_mss VNET(tcp_pmtud_blackhole_mss)
171 SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_mss,
172 CTLFLAG_RW,
173 &VNET_NAME(tcp_pmtud_blackhole_mss), 0,
174 "Path MTU Discovery Black Hole Detection lowered MSS");
175 #endif
176
177 #ifdef INET6
178 static VNET_DEFINE(int, tcp_v6pmtud_blackhole_mss) = 1220;
179 #define V_tcp_v6pmtud_blackhole_mss VNET(tcp_v6pmtud_blackhole_mss)
180 SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, v6pmtud_blackhole_mss,
181 CTLFLAG_RW,
182 &VNET_NAME(tcp_v6pmtud_blackhole_mss), 0,
183 "Path MTU Discovery IPv6 Black Hole Detection lowered MSS");
184 #endif
185
186 static int per_cpu_timers = 0;
187 SYSCTL_INT(_net_inet_tcp, OID_AUTO, per_cpu_timers, CTLFLAG_RW,
188 &per_cpu_timers , 0, "run tcp timers on all cpus");
189
190 #define INP_CPU(inp) (per_cpu_timers ? (!CPU_ABSENT(((inp)->inp_flowid % (mp_maxid+1))) ? \
191 ((inp)->inp_flowid % (mp_maxid+1)) : curcpu) : 0)
192
193 /*
194 * Tcp protocol timeout routine called every 500 ms.
195 * Updates timestamps used for TCP
196 * causes finite state machine actions if timers expire.
197 */
198 void
199 tcp_slowtimo(void)
200 {
201 VNET_ITERATOR_DECL(vnet_iter);
202
203 VNET_LIST_RLOCK_NOSLEEP();
204 VNET_FOREACH(vnet_iter) {
205 CURVNET_SET(vnet_iter);
206 (void) tcp_tw_2msl_scan(0);
207 CURVNET_RESTORE();
208 }
209 VNET_LIST_RUNLOCK_NOSLEEP();
210 }
211
212 int tcp_syn_backoff[TCP_MAXRXTSHIFT + 1] =
213 { 1, 1, 1, 1, 1, 2, 4, 8, 16, 32, 64, 64, 64 };
214
215 int tcp_backoff[TCP_MAXRXTSHIFT + 1] =
216 { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 512, 512, 512 };
217
218 static int tcp_totbackoff = 2559; /* sum of tcp_backoff[] */
219
220 /*
221 * TCP timer processing.
222 */
223
224 void
225 tcp_timer_delack(void *xtp)
226 {
227 struct tcpcb *tp = xtp;
228 struct inpcb *inp;
229 CURVNET_SET(tp->t_vnet);
230
231 inp = tp->t_inpcb;
232 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
233 INP_WLOCK(inp);
234 if (callout_pending(&tp->t_timers->tt_delack) ||
235 !callout_active(&tp->t_timers->tt_delack)) {
236 INP_WUNLOCK(inp);
237 CURVNET_RESTORE();
238 return;
239 }
240 callout_deactivate(&tp->t_timers->tt_delack);
241 if ((inp->inp_flags & INP_DROPPED) != 0) {
242 INP_WUNLOCK(inp);
243 CURVNET_RESTORE();
244 return;
245 }
246 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
247 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
248 KASSERT((tp->t_timers->tt_flags & TT_DELACK) != 0,
249 ("%s: tp %p delack callout should be running", __func__, tp));
250
251 tp->t_flags |= TF_ACKNOW;
252 TCPSTAT_INC(tcps_delack);
253 (void) tcp_output(tp);
254 INP_WUNLOCK(inp);
255 CURVNET_RESTORE();
256 }
257
258 void
259 tcp_timer_2msl(void *xtp)
260 {
261 struct tcpcb *tp = xtp;
262 struct inpcb *inp;
263 CURVNET_SET(tp->t_vnet);
264 #ifdef TCPDEBUG
265 int ostate;
266
267 ostate = tp->t_state;
268 #endif
269 INP_INFO_RLOCK(&V_tcbinfo);
270 inp = tp->t_inpcb;
271 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
272 INP_WLOCK(inp);
273 tcp_free_sackholes(tp);
274 if (callout_pending(&tp->t_timers->tt_2msl) ||
275 !callout_active(&tp->t_timers->tt_2msl)) {
276 INP_WUNLOCK(tp->t_inpcb);
277 INP_INFO_RUNLOCK(&V_tcbinfo);
278 CURVNET_RESTORE();
279 return;
280 }
281 callout_deactivate(&tp->t_timers->tt_2msl);
282 if ((inp->inp_flags & INP_DROPPED) != 0) {
283 INP_WUNLOCK(inp);
284 INP_INFO_RUNLOCK(&V_tcbinfo);
285 CURVNET_RESTORE();
286 return;
287 }
288 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
289 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
290 KASSERT((tp->t_timers->tt_flags & TT_2MSL) != 0,
291 ("%s: tp %p 2msl callout should be running", __func__, tp));
292 /*
293 * 2 MSL timeout in shutdown went off. If we're closed but
294 * still waiting for peer to close and connection has been idle
295 * too long delete connection control block. Otherwise, check
296 * again in a bit.
297 *
298 * If in TIME_WAIT state just ignore as this timeout is handled in
299 * tcp_tw_2msl_scan().
300 *
301 * If fastrecycle of FIN_WAIT_2, in FIN_WAIT_2 and receiver has closed,
302 * there's no point in hanging onto FIN_WAIT_2 socket. Just close it.
303 * Ignore fact that there were recent incoming segments.
304 */
305 if ((inp->inp_flags & INP_TIMEWAIT) != 0) {
306 INP_WUNLOCK(inp);
307 INP_INFO_RUNLOCK(&V_tcbinfo);
308 CURVNET_RESTORE();
309 return;
310 }
311 if (tcp_fast_finwait2_recycle && tp->t_state == TCPS_FIN_WAIT_2 &&
312 tp->t_inpcb && tp->t_inpcb->inp_socket &&
313 (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE)) {
314 TCPSTAT_INC(tcps_finwait2_drops);
315 tp = tcp_close(tp);
316 } else {
317 if (ticks - tp->t_rcvtime <= TP_MAXIDLE(tp)) {
318 if (!callout_reset(&tp->t_timers->tt_2msl,
319 TP_KEEPINTVL(tp), tcp_timer_2msl, tp)) {
320 tp->t_timers->tt_flags &= ~TT_2MSL_RST;
321 }
322 } else
323 tp = tcp_close(tp);
324 }
325
326 #ifdef TCPDEBUG
327 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
328 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
329 PRU_SLOWTIMO);
330 #endif
331 if (tp != NULL)
332 INP_WUNLOCK(inp);
333 INP_INFO_RUNLOCK(&V_tcbinfo);
334 CURVNET_RESTORE();
335 }
336
337 void
338 tcp_timer_keep(void *xtp)
339 {
340 struct tcpcb *tp = xtp;
341 struct tcptemp *t_template;
342 struct inpcb *inp;
343 CURVNET_SET(tp->t_vnet);
344 #ifdef TCPDEBUG
345 int ostate;
346
347 ostate = tp->t_state;
348 #endif
349 INP_INFO_RLOCK(&V_tcbinfo);
350 inp = tp->t_inpcb;
351 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
352 INP_WLOCK(inp);
353 if (callout_pending(&tp->t_timers->tt_keep) ||
354 !callout_active(&tp->t_timers->tt_keep)) {
355 INP_WUNLOCK(inp);
356 INP_INFO_RUNLOCK(&V_tcbinfo);
357 CURVNET_RESTORE();
358 return;
359 }
360 callout_deactivate(&tp->t_timers->tt_keep);
361 if ((inp->inp_flags & INP_DROPPED) != 0) {
362 INP_WUNLOCK(inp);
363 INP_INFO_RUNLOCK(&V_tcbinfo);
364 CURVNET_RESTORE();
365 return;
366 }
367 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
368 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
369 KASSERT((tp->t_timers->tt_flags & TT_KEEP) != 0,
370 ("%s: tp %p keep callout should be running", __func__, tp));
371 /*
372 * Keep-alive timer went off; send something
373 * or drop connection if idle for too long.
374 */
375 TCPSTAT_INC(tcps_keeptimeo);
376 if (tp->t_state < TCPS_ESTABLISHED)
377 goto dropit;
378 if ((always_keepalive || inp->inp_socket->so_options & SO_KEEPALIVE) &&
379 tp->t_state <= TCPS_CLOSING) {
380 if (ticks - tp->t_rcvtime >= TP_KEEPIDLE(tp) + TP_MAXIDLE(tp))
381 goto dropit;
382 /*
383 * Send a packet designed to force a response
384 * if the peer is up and reachable:
385 * either an ACK if the connection is still alive,
386 * or an RST if the peer has closed the connection
387 * due to timeout or reboot.
388 * Using sequence number tp->snd_una-1
389 * causes the transmitted zero-length segment
390 * to lie outside the receive window;
391 * by the protocol spec, this requires the
392 * correspondent TCP to respond.
393 */
394 TCPSTAT_INC(tcps_keepprobe);
395 t_template = tcpip_maketemplate(inp);
396 if (t_template) {
397 tcp_respond(tp, t_template->tt_ipgen,
398 &t_template->tt_t, (struct mbuf *)NULL,
399 tp->rcv_nxt, tp->snd_una - 1, 0);
400 free(t_template, M_TEMP);
401 }
402 if (!callout_reset(&tp->t_timers->tt_keep, TP_KEEPINTVL(tp),
403 tcp_timer_keep, tp)) {
404 tp->t_timers->tt_flags &= ~TT_KEEP_RST;
405 }
406 } else if (!callout_reset(&tp->t_timers->tt_keep, TP_KEEPIDLE(tp),
407 tcp_timer_keep, tp)) {
408 tp->t_timers->tt_flags &= ~TT_KEEP_RST;
409 }
410
411 #ifdef TCPDEBUG
412 if (inp->inp_socket->so_options & SO_DEBUG)
413 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
414 PRU_SLOWTIMO);
415 #endif
416 INP_WUNLOCK(inp);
417 INP_INFO_RUNLOCK(&V_tcbinfo);
418 CURVNET_RESTORE();
419 return;
420
421 dropit:
422 TCPSTAT_INC(tcps_keepdrops);
423 tp = tcp_drop(tp, ETIMEDOUT);
424
425 #ifdef TCPDEBUG
426 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
427 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
428 PRU_SLOWTIMO);
429 #endif
430 if (tp != NULL)
431 INP_WUNLOCK(tp->t_inpcb);
432 INP_INFO_RUNLOCK(&V_tcbinfo);
433 CURVNET_RESTORE();
434 }
435
436 void
437 tcp_timer_persist(void *xtp)
438 {
439 struct tcpcb *tp = xtp;
440 struct inpcb *inp;
441 CURVNET_SET(tp->t_vnet);
442 #ifdef TCPDEBUG
443 int ostate;
444
445 ostate = tp->t_state;
446 #endif
447 INP_INFO_RLOCK(&V_tcbinfo);
448 inp = tp->t_inpcb;
449 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
450 INP_WLOCK(inp);
451 if (callout_pending(&tp->t_timers->tt_persist) ||
452 !callout_active(&tp->t_timers->tt_persist)) {
453 INP_WUNLOCK(inp);
454 INP_INFO_RUNLOCK(&V_tcbinfo);
455 CURVNET_RESTORE();
456 return;
457 }
458 callout_deactivate(&tp->t_timers->tt_persist);
459 if ((inp->inp_flags & INP_DROPPED) != 0) {
460 INP_WUNLOCK(inp);
461 INP_INFO_RUNLOCK(&V_tcbinfo);
462 CURVNET_RESTORE();
463 return;
464 }
465 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
466 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
467 KASSERT((tp->t_timers->tt_flags & TT_PERSIST) != 0,
468 ("%s: tp %p persist callout should be running", __func__, tp));
469 /*
470 * Persistance timer into zero window.
471 * Force a byte to be output, if possible.
472 */
473 TCPSTAT_INC(tcps_persisttimeo);
474 /*
475 * Hack: if the peer is dead/unreachable, we do not
476 * time out if the window is closed. After a full
477 * backoff, drop the connection if the idle time
478 * (no responses to probes) reaches the maximum
479 * backoff that we would use if retransmitting.
480 */
481 if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
482 (ticks - tp->t_rcvtime >= tcp_maxpersistidle ||
483 ticks - tp->t_rcvtime >= TCP_REXMTVAL(tp) * tcp_totbackoff)) {
484 TCPSTAT_INC(tcps_persistdrop);
485 tp = tcp_drop(tp, ETIMEDOUT);
486 goto out;
487 }
488 /*
489 * If the user has closed the socket then drop a persisting
490 * connection after a much reduced timeout.
491 */
492 if (tp->t_state > TCPS_CLOSE_WAIT &&
493 (ticks - tp->t_rcvtime) >= TCPTV_PERSMAX) {
494 TCPSTAT_INC(tcps_persistdrop);
495 tp = tcp_drop(tp, ETIMEDOUT);
496 goto out;
497 }
498 tcp_setpersist(tp);
499 tp->t_flags |= TF_FORCEDATA;
500 (void) tcp_output(tp);
501 tp->t_flags &= ~TF_FORCEDATA;
502
503 out:
504 #ifdef TCPDEBUG
505 if (tp != NULL && tp->t_inpcb->inp_socket->so_options & SO_DEBUG)
506 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO);
507 #endif
508 if (tp != NULL)
509 INP_WUNLOCK(inp);
510 INP_INFO_RUNLOCK(&V_tcbinfo);
511 CURVNET_RESTORE();
512 }
513
514 void
515 tcp_timer_rexmt(void * xtp)
516 {
517 struct tcpcb *tp = xtp;
518 CURVNET_SET(tp->t_vnet);
519 int rexmt;
520 int headlocked;
521 struct inpcb *inp;
522 #ifdef TCPDEBUG
523 int ostate;
524
525 ostate = tp->t_state;
526 #endif
527
528 INP_INFO_RLOCK(&V_tcbinfo);
529 inp = tp->t_inpcb;
530 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
531 INP_WLOCK(inp);
532 if (callout_pending(&tp->t_timers->tt_rexmt) ||
533 !callout_active(&tp->t_timers->tt_rexmt)) {
534 INP_WUNLOCK(inp);
535 INP_INFO_RUNLOCK(&V_tcbinfo);
536 CURVNET_RESTORE();
537 return;
538 }
539 callout_deactivate(&tp->t_timers->tt_rexmt);
540 if ((inp->inp_flags & INP_DROPPED) != 0) {
541 INP_WUNLOCK(inp);
542 INP_INFO_RUNLOCK(&V_tcbinfo);
543 CURVNET_RESTORE();
544 return;
545 }
546 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
547 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
548 KASSERT((tp->t_timers->tt_flags & TT_REXMT) != 0,
549 ("%s: tp %p rexmt callout should be running", __func__, tp));
550 tcp_free_sackholes(tp);
551 /*
552 * Retransmission timer went off. Message has not
553 * been acked within retransmit interval. Back off
554 * to a longer retransmit interval and retransmit one segment.
555 */
556 if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) {
557 tp->t_rxtshift = TCP_MAXRXTSHIFT;
558 TCPSTAT_INC(tcps_timeoutdrop);
559
560 tp = tcp_drop(tp, tp->t_softerror ?
561 tp->t_softerror : ETIMEDOUT);
562 headlocked = 1;
563 goto out;
564 }
565 INP_INFO_RUNLOCK(&V_tcbinfo);
566 headlocked = 0;
567 if (tp->t_state == TCPS_SYN_SENT) {
568 /*
569 * If the SYN was retransmitted, indicate CWND to be
570 * limited to 1 segment in cc_conn_init().
571 */
572 tp->snd_cwnd = 1;
573 } else if (tp->t_rxtshift == 1) {
574 /*
575 * first retransmit; record ssthresh and cwnd so they can
576 * be recovered if this turns out to be a "bad" retransmit.
577 * A retransmit is considered "bad" if an ACK for this
578 * segment is received within RTT/2 interval; the assumption
579 * here is that the ACK was already in flight. See
580 * "On Estimating End-to-End Network Path Properties" by
581 * Allman and Paxson for more details.
582 */
583 tp->snd_cwnd_prev = tp->snd_cwnd;
584 tp->snd_ssthresh_prev = tp->snd_ssthresh;
585 tp->snd_recover_prev = tp->snd_recover;
586 if (IN_FASTRECOVERY(tp->t_flags))
587 tp->t_flags |= TF_WASFRECOVERY;
588 else
589 tp->t_flags &= ~TF_WASFRECOVERY;
590 if (IN_CONGRECOVERY(tp->t_flags))
591 tp->t_flags |= TF_WASCRECOVERY;
592 else
593 tp->t_flags &= ~TF_WASCRECOVERY;
594 tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1));
595 tp->t_flags |= TF_PREVVALID;
596 } else
597 tp->t_flags &= ~TF_PREVVALID;
598 TCPSTAT_INC(tcps_rexmttimeo);
599 if ((tp->t_state == TCPS_SYN_SENT) ||
600 (tp->t_state == TCPS_SYN_RECEIVED))
601 rexmt = TCPTV_RTOBASE * tcp_syn_backoff[tp->t_rxtshift];
602 else
603 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
604 TCPT_RANGESET(tp->t_rxtcur, rexmt,
605 tp->t_rttmin, TCPTV_REXMTMAX);
606
607 /*
608 * We enter the path for PLMTUD if connection is established or, if
609 * connection is FIN_WAIT_1 status, reason for the last is that if
610 * amount of data we send is very small, we could send it in couple of
611 * packets and process straight to FIN. In that case we won't catch
612 * ESTABLISHED state.
613 */
614 if (V_tcp_pmtud_blackhole_detect && (((tp->t_state == TCPS_ESTABLISHED))
615 || (tp->t_state == TCPS_FIN_WAIT_1))) {
616 int optlen;
617 #ifdef INET6
618 int isipv6;
619 #endif
620
621 /*
622 * Idea here is that at each stage of mtu probe (usually, 1448
623 * -> 1188 -> 524) should be given 2 chances to recover before
624 * further clamping down. 'tp->t_rxtshift % 2 == 0' should
625 * take care of that.
626 */
627 if (((tp->t_flags2 & (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) ==
628 (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) &&
629 (tp->t_rxtshift >= 2 && tp->t_rxtshift % 2 == 0)) {
630 /*
631 * Enter Path MTU Black-hole Detection mechanism:
632 * - Disable Path MTU Discovery (IP "DF" bit).
633 * - Reduce MTU to lower value than what we
634 * negotiated with peer.
635 */
636 /* Record that we may have found a black hole. */
637 tp->t_flags2 |= TF2_PLPMTU_BLACKHOLE;
638
639 /* Keep track of previous MSS. */
640 optlen = tp->t_maxopd - tp->t_maxseg;
641 tp->t_pmtud_saved_maxopd = tp->t_maxopd;
642
643 /*
644 * Reduce the MSS to blackhole value or to the default
645 * in an attempt to retransmit.
646 */
647 #ifdef INET6
648 isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) ? 1 : 0;
649 if (isipv6 &&
650 tp->t_maxopd > V_tcp_v6pmtud_blackhole_mss) {
651 /* Use the sysctl tuneable blackhole MSS. */
652 tp->t_maxopd = V_tcp_v6pmtud_blackhole_mss;
653 V_tcp_pmtud_blackhole_activated++;
654 } else if (isipv6) {
655 /* Use the default MSS. */
656 tp->t_maxopd = V_tcp_v6mssdflt;
657 /*
658 * Disable Path MTU Discovery when we switch to
659 * minmss.
660 */
661 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
662 V_tcp_pmtud_blackhole_activated_min_mss++;
663 }
664 #endif
665 #if defined(INET6) && defined(INET)
666 else
667 #endif
668 #ifdef INET
669 if (tp->t_maxopd > V_tcp_pmtud_blackhole_mss) {
670 /* Use the sysctl tuneable blackhole MSS. */
671 tp->t_maxopd = V_tcp_pmtud_blackhole_mss;
672 V_tcp_pmtud_blackhole_activated++;
673 } else {
674 /* Use the default MSS. */
675 tp->t_maxopd = V_tcp_mssdflt;
676 /*
677 * Disable Path MTU Discovery when we switch to
678 * minmss.
679 */
680 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
681 V_tcp_pmtud_blackhole_activated_min_mss++;
682 }
683 #endif
684 tp->t_maxseg = tp->t_maxopd - optlen;
685 /*
686 * Reset the slow-start flight size
687 * as it may depend on the new MSS.
688 */
689 if (CC_ALGO(tp)->conn_init != NULL)
690 CC_ALGO(tp)->conn_init(tp->ccv);
691 } else {
692 /*
693 * If further retransmissions are still unsuccessful
694 * with a lowered MTU, maybe this isn't a blackhole and
695 * we restore the previous MSS and blackhole detection
696 * flags.
697 * The limit '6' is determined by giving each probe
698 * stage (1448, 1188, 524) 2 chances to recover.
699 */
700 if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) &&
701 (tp->t_rxtshift > 6)) {
702 tp->t_flags2 |= TF2_PLPMTU_PMTUD;
703 tp->t_flags2 &= ~TF2_PLPMTU_BLACKHOLE;
704 optlen = tp->t_maxopd - tp->t_maxseg;
705 tp->t_maxopd = tp->t_pmtud_saved_maxopd;
706 tp->t_maxseg = tp->t_maxopd - optlen;
707 V_tcp_pmtud_blackhole_failed++;
708 /*
709 * Reset the slow-start flight size as it
710 * may depend on the new MSS.
711 */
712 if (CC_ALGO(tp)->conn_init != NULL)
713 CC_ALGO(tp)->conn_init(tp->ccv);
714 }
715 }
716 }
717
718 /*
719 * Disable RFC1323 and SACK if we haven't got any response to
720 * our third SYN to work-around some broken terminal servers
721 * (most of which have hopefully been retired) that have bad VJ
722 * header compression code which trashes TCP segments containing
723 * unknown-to-them TCP options.
724 */
725 if (tcp_rexmit_drop_options && (tp->t_state == TCPS_SYN_SENT) &&
726 (tp->t_rxtshift == 3))
727 tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP|TF_SACK_PERMIT);
728 /*
729 * If we backed off this far, our srtt estimate is probably bogus.
730 * Clobber it so we'll take the next rtt measurement as our srtt;
731 * move the current srtt into rttvar to keep the current
732 * retransmit times until then.
733 */
734 if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) {
735 #ifdef INET6
736 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0)
737 in6_losing(tp->t_inpcb);
738 #endif
739 tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT);
740 tp->t_srtt = 0;
741 }
742 tp->snd_nxt = tp->snd_una;
743 tp->snd_recover = tp->snd_max;
744 /*
745 * Force a segment to be sent.
746 */
747 tp->t_flags |= TF_ACKNOW;
748 /*
749 * If timing a segment in this window, stop the timer.
750 */
751 tp->t_rtttime = 0;
752
753 cc_cong_signal(tp, NULL, CC_RTO);
754
755 (void) tcp_output(tp);
756
757 out:
758 #ifdef TCPDEBUG
759 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
760 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
761 PRU_SLOWTIMO);
762 #endif
763 if (tp != NULL)
764 INP_WUNLOCK(inp);
765 if (headlocked)
766 INP_INFO_RUNLOCK(&V_tcbinfo);
767 CURVNET_RESTORE();
768 }
769
770 void
771 tcp_timer_activate(struct tcpcb *tp, uint32_t timer_type, u_int delta)
772 {
773 struct callout *t_callout;
774 timeout_t *f_callout;
775 struct inpcb *inp = tp->t_inpcb;
776 int cpu = INP_CPU(inp);
777 uint32_t f_reset;
778
779 #ifdef TCP_OFFLOAD
780 if (tp->t_flags & TF_TOE)
781 return;
782 #endif
783
784 if (tp->t_timers->tt_flags & TT_STOPPED)
785 return;
786
787 switch (timer_type) {
788 case TT_DELACK:
789 t_callout = &tp->t_timers->tt_delack;
790 f_callout = tcp_timer_delack;
791 f_reset = TT_DELACK_RST;
792 break;
793 case TT_REXMT:
794 t_callout = &tp->t_timers->tt_rexmt;
795 f_callout = tcp_timer_rexmt;
796 f_reset = TT_REXMT_RST;
797 break;
798 case TT_PERSIST:
799 t_callout = &tp->t_timers->tt_persist;
800 f_callout = tcp_timer_persist;
801 f_reset = TT_PERSIST_RST;
802 break;
803 case TT_KEEP:
804 t_callout = &tp->t_timers->tt_keep;
805 f_callout = tcp_timer_keep;
806 f_reset = TT_KEEP_RST;
807 break;
808 case TT_2MSL:
809 t_callout = &tp->t_timers->tt_2msl;
810 f_callout = tcp_timer_2msl;
811 f_reset = TT_2MSL_RST;
812 break;
813 default:
814 panic("tp %p bad timer_type %#x", tp, timer_type);
815 }
816 if (delta == 0) {
817 if ((tp->t_timers->tt_flags & timer_type) &&
818 callout_stop(t_callout) &&
819 (tp->t_timers->tt_flags & f_reset)) {
820 tp->t_timers->tt_flags &= ~(timer_type | f_reset);
821 }
822 } else {
823 if ((tp->t_timers->tt_flags & timer_type) == 0) {
824 tp->t_timers->tt_flags |= (timer_type | f_reset);
825 callout_reset_on(t_callout, delta, f_callout, tp, cpu);
826 } else {
827 /* Reset already running callout on the same CPU. */
828 if (!callout_reset(t_callout, delta, f_callout, tp)) {
829 /*
830 * Callout not cancelled, consider it as not
831 * properly restarted. */
832 tp->t_timers->tt_flags &= ~f_reset;
833 }
834 }
835 }
836 }
837
838 int
839 tcp_timer_active(struct tcpcb *tp, uint32_t timer_type)
840 {
841 struct callout *t_callout;
842
843 switch (timer_type) {
844 case TT_DELACK:
845 t_callout = &tp->t_timers->tt_delack;
846 break;
847 case TT_REXMT:
848 t_callout = &tp->t_timers->tt_rexmt;
849 break;
850 case TT_PERSIST:
851 t_callout = &tp->t_timers->tt_persist;
852 break;
853 case TT_KEEP:
854 t_callout = &tp->t_timers->tt_keep;
855 break;
856 case TT_2MSL:
857 t_callout = &tp->t_timers->tt_2msl;
858 break;
859 default:
860 panic("tp %p bad timer_type %#x", tp, timer_type);
861 }
862 return callout_active(t_callout);
863 }
864
865 void
866 tcp_timer_stop(struct tcpcb *tp, uint32_t timer_type)
867 {
868 struct callout *t_callout;
869 timeout_t *f_callout;
870 uint32_t f_reset;
871
872 tp->t_timers->tt_flags |= TT_STOPPED;
873
874 switch (timer_type) {
875 case TT_DELACK:
876 t_callout = &tp->t_timers->tt_delack;
877 f_callout = tcp_timer_delack_discard;
878 f_reset = TT_DELACK_RST;
879 break;
880 case TT_REXMT:
881 t_callout = &tp->t_timers->tt_rexmt;
882 f_callout = tcp_timer_rexmt_discard;
883 f_reset = TT_REXMT_RST;
884 break;
885 case TT_PERSIST:
886 t_callout = &tp->t_timers->tt_persist;
887 f_callout = tcp_timer_persist_discard;
888 f_reset = TT_PERSIST_RST;
889 break;
890 case TT_KEEP:
891 t_callout = &tp->t_timers->tt_keep;
892 f_callout = tcp_timer_keep_discard;
893 f_reset = TT_KEEP_RST;
894 break;
895 case TT_2MSL:
896 t_callout = &tp->t_timers->tt_2msl;
897 f_callout = tcp_timer_2msl_discard;
898 f_reset = TT_2MSL_RST;
899 break;
900 default:
901 panic("tp %p bad timer_type %#x", tp, timer_type);
902 }
903
904 if (tp->t_timers->tt_flags & timer_type) {
905 if (callout_stop(t_callout) &&
906 (tp->t_timers->tt_flags & f_reset)) {
907 tp->t_timers->tt_flags &= ~(timer_type | f_reset);
908 } else {
909 /*
910 * Can't stop the callout, defer tcpcb actual deletion
911 * to the last tcp timer discard callout.
912 * The TT_STOPPED flag will ensure that no tcp timer
913 * callouts can be restarted on our behalf, and
914 * past this point currently running callouts waiting
915 * on inp lock will return right away after the
916 * classical check for callout reset/stop events:
917 * callout_pending() || !callout_active()
918 */
919 callout_reset(t_callout, 1, f_callout, tp);
920 }
921 }
922 }
923
924 #define ticks_to_msecs(t) (1000*(t) / hz)
925
926 void
927 tcp_timer_to_xtimer(struct tcpcb *tp, struct tcp_timer *timer,
928 struct xtcp_timer *xtimer)
929 {
930 sbintime_t now;
931
932 bzero(xtimer, sizeof(*xtimer));
933 if (timer == NULL)
934 return;
935 now = getsbinuptime();
936 if (callout_active(&timer->tt_delack))
937 xtimer->tt_delack = (timer->tt_delack.c_time - now) / SBT_1MS;
938 if (callout_active(&timer->tt_rexmt))
939 xtimer->tt_rexmt = (timer->tt_rexmt.c_time - now) / SBT_1MS;
940 if (callout_active(&timer->tt_persist))
941 xtimer->tt_persist = (timer->tt_persist.c_time - now) / SBT_1MS;
942 if (callout_active(&timer->tt_keep))
943 xtimer->tt_keep = (timer->tt_keep.c_time - now) / SBT_1MS;
944 if (callout_active(&timer->tt_2msl))
945 xtimer->tt_2msl = (timer->tt_2msl.c_time - now) / SBT_1MS;
946 xtimer->t_rcvtime = ticks_to_msecs(ticks - tp->t_rcvtime);
947 }
Cache object: 825f4534a46b933701bf84c7523e76ce
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