HAMMER 60I/Many: Mirroring
[dragonfly.git] / sys / netinet / tcp_timer.c
blob92332c143682cfc3727e9e3438989d6fa2a95b0f
1 /*
2 * Copyright (c) 2003, 2004 Jeffrey M. Hsu. All rights reserved.
3 * Copyright (c) 2003, 2004 The DragonFly Project. All rights reserved.
5 * This code is derived from software contributed to The DragonFly Project
6 * by Jeffrey M. Hsu.
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.
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.
35 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995
36 * The Regents of the University of California. All rights reserved.
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. All advertising materials mentioning features or use of this software
47 * must display the following acknowledgement:
48 * This product includes software developed by the University of
49 * California, Berkeley and its contributors.
50 * 4. Neither the name of the University nor the names of its contributors
51 * may be used to endorse or promote products derived from this software
52 * without specific prior written permission.
54 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
55 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
56 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
57 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
58 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
59 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
60 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
61 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
62 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
63 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
64 * SUCH DAMAGE.
66 * @(#)tcp_timer.c 8.2 (Berkeley) 5/24/95
67 * $FreeBSD: src/sys/netinet/tcp_timer.c,v 1.34.2.14 2003/02/03 02:33:41 hsu Exp $
68 * $DragonFly: src/sys/netinet/tcp_timer.c,v 1.17 2008/03/30 20:39:01 dillon Exp $
71 #include "opt_compat.h"
72 #include "opt_inet6.h"
73 #include "opt_tcpdebug.h"
75 #include <sys/param.h>
76 #include <sys/systm.h>
77 #include <sys/kernel.h>
78 #include <sys/mbuf.h>
79 #include <sys/sysctl.h>
80 #include <sys/socket.h>
81 #include <sys/socketvar.h>
82 #include <sys/protosw.h>
83 #include <sys/thread.h>
84 #include <sys/globaldata.h>
85 #include <sys/thread2.h>
87 #include <machine/cpu.h> /* before tcp_seq.h, for tcp_random18() */
89 #include <net/route.h>
91 #include <netinet/in.h>
92 #include <netinet/in_systm.h>
93 #include <netinet/in_pcb.h>
94 #ifdef INET6
95 #include <netinet6/in6_pcb.h>
96 #endif
97 #include <netinet/ip_var.h>
98 #include <netinet/tcp.h>
99 #include <netinet/tcp_fsm.h>
100 #include <netinet/tcp_seq.h>
101 #include <netinet/tcp_timer.h>
102 #include <netinet/tcp_var.h>
103 #include <netinet/tcpip.h>
104 #ifdef TCPDEBUG
105 #include <netinet/tcp_debug.h>
106 #endif
108 static int
109 sysctl_msec_to_ticks(SYSCTL_HANDLER_ARGS)
111 int error, s, tt;
113 tt = *(int *)oidp->oid_arg1;
114 s = (int)((int64_t)tt * 1000 / hz);
116 error = sysctl_handle_int(oidp, &s, 0, req);
117 if (error || !req->newptr)
118 return (error);
120 tt = (int)((int64_t)s * hz / 1000);
121 if (tt < 1)
122 return (EINVAL);
124 *(int *)oidp->oid_arg1 = tt;
125 return (0);
128 int tcp_keepinit;
129 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit, CTLTYPE_INT|CTLFLAG_RW,
130 &tcp_keepinit, 0, sysctl_msec_to_ticks, "I", "");
132 int tcp_keepidle;
133 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle, CTLTYPE_INT|CTLFLAG_RW,
134 &tcp_keepidle, 0, sysctl_msec_to_ticks, "I", "");
136 int tcp_keepintvl;
137 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl, CTLTYPE_INT|CTLFLAG_RW,
138 &tcp_keepintvl, 0, sysctl_msec_to_ticks, "I", "");
140 int tcp_delacktime;
141 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DELACKTIME, delacktime,
142 CTLTYPE_INT|CTLFLAG_RW, &tcp_delacktime, 0, sysctl_msec_to_ticks, "I",
143 "Time before a delayed ACK is sent");
145 int tcp_msl;
146 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl, CTLTYPE_INT|CTLFLAG_RW,
147 &tcp_msl, 0, sysctl_msec_to_ticks, "I", "Maximum segment lifetime");
149 int tcp_rexmit_min;
150 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_min, CTLTYPE_INT|CTLFLAG_RW,
151 &tcp_rexmit_min, 0, sysctl_msec_to_ticks, "I", "Minimum Retransmission Timeout");
153 int tcp_rexmit_slop;
154 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_slop, CTLTYPE_INT|CTLFLAG_RW,
155 &tcp_rexmit_slop, 0, sysctl_msec_to_ticks, "I",
156 "Retransmission Timer Slop");
158 static int always_keepalive = 1;
159 SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive, CTLFLAG_RW,
160 &always_keepalive , 0, "Assume SO_KEEPALIVE on all TCP connections");
162 static int tcp_keepcnt = TCPTV_KEEPCNT;
163 /* max idle probes */
164 int tcp_maxpersistidle;
165 /* max idle time in persist */
166 int tcp_maxidle;
169 * Tcp protocol timeout routine called every 500 ms.
170 * Updates timestamps used for TCP
171 * causes finite state machine actions if timers expire.
173 void
174 tcp_slowtimo(void)
176 crit_enter();
177 tcp_maxidle = tcp_keepcnt * tcp_keepintvl;
178 crit_exit();
182 * Cancel all timers for TCP tp.
184 void
185 tcp_canceltimers(struct tcpcb *tp)
187 callout_stop(tp->tt_2msl);
188 callout_stop(tp->tt_persist);
189 callout_stop(tp->tt_keep);
190 callout_stop(tp->tt_rexmt);
193 int tcp_syn_backoff[TCP_MAXRXTSHIFT + 1] =
194 { 1, 1, 1, 1, 1, 2, 4, 8, 16, 32, 64, 64, 64 };
196 int tcp_backoff[TCP_MAXRXTSHIFT + 1] =
197 { 1, 2, 4, 8, 16, 32, 64, 64, 64, 64, 64, 64, 64 };
199 static int tcp_totbackoff = 511; /* sum of tcp_backoff[] */
202 * TCP timer processing.
204 void
205 tcp_timer_delack(void *xtp)
207 struct tcpcb *tp = xtp;
209 crit_enter();
210 if (callout_pending(tp->tt_delack) || !callout_active(tp->tt_delack)) {
211 crit_exit();
212 return;
214 callout_deactivate(tp->tt_delack);
216 tp->t_flags |= TF_ACKNOW;
217 tcpstat.tcps_delack++;
218 tcp_output(tp);
219 crit_exit();
222 void
223 tcp_timer_2msl(void *xtp)
225 struct tcpcb *tp = xtp;
226 #ifdef TCPDEBUG
227 int ostate;
229 ostate = tp->t_state;
230 #endif
231 crit_enter();
232 if (callout_pending(tp->tt_2msl) || !callout_active(tp->tt_2msl)) {
233 crit_exit();
234 return;
236 callout_deactivate(tp->tt_2msl);
238 * 2 MSL timeout in shutdown went off. If we're closed but
239 * still waiting for peer to close and connection has been idle
240 * too long, or if 2MSL time is up from TIME_WAIT, delete connection
241 * control block. Otherwise, check again in a bit.
243 if (tp->t_state != TCPS_TIME_WAIT &&
244 (ticks - tp->t_rcvtime) <= tcp_maxidle)
245 callout_reset(tp->tt_2msl, tcp_keepintvl,
246 tcp_timer_2msl, tp);
247 else
248 tp = tcp_close(tp);
250 #ifdef TCPDEBUG
251 if (tp && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
252 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO);
253 #endif
254 crit_exit();
257 void
258 tcp_timer_keep(void *xtp)
260 struct tcpcb *tp = xtp;
261 struct tcptemp *t_template;
262 #ifdef TCPDEBUG
263 int ostate;
265 ostate = tp->t_state;
266 #endif
267 crit_enter();
268 if (callout_pending(tp->tt_keep) || !callout_active(tp->tt_keep)) {
269 crit_exit();
270 return;
272 callout_deactivate(tp->tt_keep);
274 * Keep-alive timer went off; send something
275 * or drop connection if idle for too long.
277 tcpstat.tcps_keeptimeo++;
278 if (tp->t_state < TCPS_ESTABLISHED)
279 goto dropit;
280 if ((always_keepalive ||
281 tp->t_inpcb->inp_socket->so_options & SO_KEEPALIVE) &&
282 tp->t_state <= TCPS_CLOSING) {
283 if ((ticks - tp->t_rcvtime) >= tcp_keepidle + tcp_maxidle)
284 goto dropit;
286 * Send a packet designed to force a response
287 * if the peer is up and reachable:
288 * either an ACK if the connection is still alive,
289 * or an RST if the peer has closed the connection
290 * due to timeout or reboot.
291 * Using sequence number tp->snd_una-1
292 * causes the transmitted zero-length segment
293 * to lie outside the receive window;
294 * by the protocol spec, this requires the
295 * correspondent TCP to respond.
297 tcpstat.tcps_keepprobe++;
298 t_template = tcp_maketemplate(tp);
299 if (t_template) {
300 tcp_respond(tp, t_template->tt_ipgen,
301 &t_template->tt_t, (struct mbuf *)NULL,
302 tp->rcv_nxt, tp->snd_una - 1, 0);
303 tcp_freetemplate(t_template);
305 callout_reset(tp->tt_keep, tcp_keepintvl, tcp_timer_keep, tp);
306 } else
307 callout_reset(tp->tt_keep, tcp_keepidle, tcp_timer_keep, tp);
309 #ifdef TCPDEBUG
310 if (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)
311 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO);
312 #endif
313 crit_exit();
314 return;
316 dropit:
317 tcpstat.tcps_keepdrops++;
318 tp = tcp_drop(tp, ETIMEDOUT);
320 #ifdef TCPDEBUG
321 if (tp && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
322 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO);
323 #endif
324 crit_exit();
327 void
328 tcp_timer_persist(void *xtp)
330 struct tcpcb *tp = xtp;
331 #ifdef TCPDEBUG
332 int ostate;
334 ostate = tp->t_state;
335 #endif
336 crit_enter();
337 if (callout_pending(tp->tt_persist) || !callout_active(tp->tt_persist)){
338 crit_exit();
339 return;
341 callout_deactivate(tp->tt_persist);
343 * Persistance timer into zero window.
344 * Force a byte to be output, if possible.
346 tcpstat.tcps_persisttimeo++;
348 * Hack: if the peer is dead/unreachable, we do not
349 * time out if the window is closed. After a full
350 * backoff, drop the connection if the idle time
351 * (no responses to probes) reaches the maximum
352 * backoff that we would use if retransmitting.
354 if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
355 ((ticks - tp->t_rcvtime) >= tcp_maxpersistidle ||
356 (ticks - tp->t_rcvtime) >= TCP_REXMTVAL(tp) * tcp_totbackoff)) {
357 tcpstat.tcps_persistdrop++;
358 tp = tcp_drop(tp, ETIMEDOUT);
359 goto out;
361 tcp_setpersist(tp);
362 tp->t_flags |= TF_FORCE;
363 tcp_output(tp);
364 tp->t_flags &= ~TF_FORCE;
366 out:
367 #ifdef TCPDEBUG
368 if (tp && tp->t_inpcb->inp_socket->so_options & SO_DEBUG)
369 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO);
370 #endif
371 crit_exit();
374 void
375 tcp_save_congestion_state(struct tcpcb *tp)
377 tp->snd_cwnd_prev = tp->snd_cwnd;
378 tp->snd_wacked_prev = tp->snd_wacked;
379 tp->snd_ssthresh_prev = tp->snd_ssthresh;
380 tp->snd_recover_prev = tp->snd_recover;
381 if (IN_FASTRECOVERY(tp))
382 tp->t_flags |= TF_WASFRECOVERY;
383 else
384 tp->t_flags &= ~TF_WASFRECOVERY;
385 if (tp->t_flags & TF_RCVD_TSTMP) {
386 tp->t_rexmtTS = ticks;
387 tp->t_flags |= TF_FIRSTACCACK;
389 #ifdef later
390 tcp_sack_save_scoreboard(&tp->scb);
391 #endif
394 void
395 tcp_revert_congestion_state(struct tcpcb *tp)
397 tp->snd_cwnd = tp->snd_cwnd_prev;
398 tp->snd_wacked = tp->snd_wacked_prev;
399 tp->snd_ssthresh = tp->snd_ssthresh_prev;
400 tp->snd_recover = tp->snd_recover_prev;
401 if (tp->t_flags & TF_WASFRECOVERY)
402 ENTER_FASTRECOVERY(tp);
403 if (tp->t_flags & TF_FASTREXMT) {
404 ++tcpstat.tcps_sndfastrexmitbad;
405 if (tp->t_flags & TF_EARLYREXMT)
406 ++tcpstat.tcps_sndearlyrexmitbad;
407 } else
408 ++tcpstat.tcps_sndrtobad;
409 tp->t_badrxtwin = 0;
410 tp->t_rxtshift = 0;
411 tp->snd_nxt = tp->snd_max;
412 #ifdef later
413 tcp_sack_revert_scoreboard(&tp->scb, tp->snd_una);
414 #endif
417 void
418 tcp_timer_rexmt(void *xtp)
420 struct tcpcb *tp = xtp;
421 int rexmt;
422 #ifdef TCPDEBUG
423 int ostate;
425 ostate = tp->t_state;
426 #endif
427 crit_enter();
428 if (callout_pending(tp->tt_rexmt) || !callout_active(tp->tt_rexmt)) {
429 crit_exit();
430 return;
432 callout_deactivate(tp->tt_rexmt);
434 * Retransmission timer went off. Message has not
435 * been acked within retransmit interval. Back off
436 * to a longer retransmit interval and retransmit one segment.
438 if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) {
439 tp->t_rxtshift = TCP_MAXRXTSHIFT;
440 tcpstat.tcps_timeoutdrop++;
441 tp = tcp_drop(tp, tp->t_softerror ?
442 tp->t_softerror : ETIMEDOUT);
443 goto out;
445 if (tp->t_rxtshift == 1) {
447 * first retransmit; record ssthresh and cwnd so they can
448 * be recovered if this turns out to be a "bad" retransmit.
449 * A retransmit is considered "bad" if an ACK for this
450 * segment is received within RTT/2 interval; the assumption
451 * here is that the ACK was already in flight. See
452 * "On Estimating End-to-End Network Path Properties" by
453 * Allman and Paxson for more details.
455 tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1));
456 tcp_save_congestion_state(tp);
457 tp->t_flags &= ~(TF_FASTREXMT | TF_EARLYREXMT);
459 /* Throw away SACK blocks on a RTO, as specified by RFC2018. */
460 tcp_sack_cleanup(&tp->scb);
461 tcpstat.tcps_rexmttimeo++;
462 if (tp->t_state == TCPS_SYN_SENT)
463 rexmt = TCP_REXMTVAL(tp) * tcp_syn_backoff[tp->t_rxtshift];
464 else
465 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
466 TCPT_RANGESET(tp->t_rxtcur, rexmt,
467 tp->t_rttmin, TCPTV_REXMTMAX);
469 * Disable rfc1323 and rfc1644 if we havn't got any response to
470 * our third SYN to work-around some broken terminal servers
471 * (most of which have hopefully been retired) that have bad VJ
472 * header compression code which trashes TCP segments containing
473 * unknown-to-them TCP options.
475 if ((tp->t_state == TCPS_SYN_SENT) && (tp->t_rxtshift == 3))
476 tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP|TF_REQ_CC);
478 * If losing, let the lower level know and try for
479 * a better route. Also, if we backed off this far,
480 * our srtt estimate is probably bogus. Clobber it
481 * so we'll take the next rtt measurement as our srtt;
482 * move the current srtt into rttvar to keep the current
483 * retransmit times until then.
485 if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) {
486 #ifdef INET6
487 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0)
488 in6_losing(tp->t_inpcb);
489 else
490 #endif
491 in_losing(tp->t_inpcb);
492 tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT);
493 tp->t_srtt = 0;
495 tp->snd_nxt = tp->snd_una;
496 tp->rexmt_high = tp->snd_una;
497 tp->snd_recover = tp->snd_max;
499 * Force a segment to be sent.
501 tp->t_flags |= TF_ACKNOW;
503 * If timing a segment in this window, stop the timer.
505 tp->t_rtttime = 0;
507 * Close the congestion window down to one segment
508 * (we'll open it by one segment for each ack we get).
509 * Since we probably have a window's worth of unacked
510 * data accumulated, this "slow start" keeps us from
511 * dumping all that data as back-to-back packets (which
512 * might overwhelm an intermediate gateway).
514 * There are two phases to the opening: Initially we
515 * open by one mss on each ack. This makes the window
516 * size increase exponentially with time. If the
517 * window is larger than the path can handle, this
518 * exponential growth results in dropped packet(s)
519 * almost immediately. To get more time between
520 * drops but still "push" the network to take advantage
521 * of improving conditions, we switch from exponential
522 * to linear window opening at some threshhold size.
523 * For a threshhold, we use half the current window
524 * size, truncated to a multiple of the mss.
526 * (the minimum cwnd that will give us exponential
527 * growth is 2 mss. We don't allow the threshhold
528 * to go below this.)
531 u_int win = min(tp->snd_wnd, tp->snd_cwnd) / 2 / tp->t_maxseg;
533 if (win < 2)
534 win = 2;
535 tp->snd_cwnd = tp->t_maxseg;
536 tp->snd_wacked = 0;
537 tp->snd_ssthresh = win * tp->t_maxseg;
538 tp->t_dupacks = 0;
540 EXIT_FASTRECOVERY(tp);
541 tcp_output(tp);
543 out:
544 #ifdef TCPDEBUG
545 if (tp && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
546 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO);
547 #endif
548 crit_exit();