2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995
5 * The Regents of the University of California. All rights reserved.
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8 * modification, are permitted provided that the following conditions
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15 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
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19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * @(#)tcp_timer.c 8.2 (Berkeley) 5/24/95
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
38 #include "opt_inet6.h"
39 #include "opt_tcpdebug.h"
42 #include <sys/param.h>
43 #include <sys/kernel.h>
46 #include <sys/mutex.h>
47 #include <sys/protosw.h>
49 #include <sys/socket.h>
50 #include <sys/socketvar.h>
51 #include <sys/sysctl.h>
52 #include <sys/systm.h>
55 #include <net/route.h>
56 #include <net/rss_config.h>
58 #include <net/netisr.h>
60 #include <netinet/in.h>
61 #include <netinet/in_kdtrace.h>
62 #include <netinet/in_pcb.h>
63 #include <netinet/in_rss.h>
64 #include <netinet/in_systm.h>
66 #include <netinet6/in6_pcb.h>
68 #include <netinet/ip_var.h>
69 #include <netinet/tcp.h>
70 #include <netinet/tcp_fsm.h>
71 #include <netinet/tcp_log_buf.h>
72 #include <netinet/tcp_timer.h>
73 #include <netinet/tcp_var.h>
74 #include <netinet/tcp_seq.h>
75 #include <netinet/cc/cc.h>
77 #include <netinet6/tcp6_var.h>
79 #include <netinet/tcpip.h>
81 #include <netinet/tcp_debug.h>
85 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, persmin, CTLTYPE_INT|CTLFLAG_RW,
86 &tcp_persmin, 0, sysctl_msec_to_ticks, "I", "minimum persistence interval");
89 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, persmax, CTLTYPE_INT|CTLFLAG_RW,
90 &tcp_persmax, 0, sysctl_msec_to_ticks, "I", "maximum persistence interval");
93 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit, CTLTYPE_INT|CTLFLAG_RW,
94 &tcp_keepinit, 0, sysctl_msec_to_ticks, "I", "time to establish connection");
97 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle, CTLTYPE_INT|CTLFLAG_RW,
98 &tcp_keepidle, 0, sysctl_msec_to_ticks, "I", "time before keepalive probes begin");
101 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl, CTLTYPE_INT|CTLFLAG_RW,
102 &tcp_keepintvl, 0, sysctl_msec_to_ticks, "I", "time between keepalive probes");
105 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DELACKTIME, delacktime, CTLTYPE_INT|CTLFLAG_RW,
106 &tcp_delacktime, 0, sysctl_msec_to_ticks, "I",
107 "Time before a delayed ACK is sent");
110 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl, CTLTYPE_INT|CTLFLAG_RW,
111 &tcp_msl, 0, sysctl_msec_to_ticks, "I", "Maximum segment lifetime");
113 int tcp_rexmit_initial;
114 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_initial, CTLTYPE_INT|CTLFLAG_RW,
115 &tcp_rexmit_initial, 0, sysctl_msec_to_ticks, "I",
116 "Initial Retransmission Timeout");
119 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_min, CTLTYPE_INT|CTLFLAG_RW,
120 &tcp_rexmit_min, 0, sysctl_msec_to_ticks, "I",
121 "Minimum Retransmission Timeout");
124 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_slop, CTLTYPE_INT|CTLFLAG_RW,
125 &tcp_rexmit_slop, 0, sysctl_msec_to_ticks, "I",
126 "Retransmission Timer Slop");
128 VNET_DEFINE(int, tcp_always_keepalive) = 1;
129 SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive, CTLFLAG_VNET|CTLFLAG_RW,
130 &VNET_NAME(tcp_always_keepalive) , 0,
131 "Assume SO_KEEPALIVE on all TCP connections");
133 int tcp_fast_finwait2_recycle = 0;
134 SYSCTL_INT(_net_inet_tcp, OID_AUTO, fast_finwait2_recycle, CTLFLAG_RW,
135 &tcp_fast_finwait2_recycle, 0,
136 "Recycle closed FIN_WAIT_2 connections faster");
138 int tcp_finwait2_timeout;
139 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, finwait2_timeout, CTLTYPE_INT|CTLFLAG_RW,
140 &tcp_finwait2_timeout, 0, sysctl_msec_to_ticks, "I", "FIN-WAIT2 timeout");
142 int tcp_keepcnt = TCPTV_KEEPCNT;
143 SYSCTL_INT(_net_inet_tcp, OID_AUTO, keepcnt, CTLFLAG_RW, &tcp_keepcnt, 0,
144 "Number of keepalive probes to send");
146 /* max idle probes */
147 int tcp_maxpersistidle;
149 int tcp_rexmit_drop_options = 0;
150 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rexmit_drop_options, CTLFLAG_RW,
151 &tcp_rexmit_drop_options, 0,
152 "Drop TCP options from 3rd and later retransmitted SYN");
154 VNET_DEFINE(int, tcp_pmtud_blackhole_detect);
155 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_detection,
156 CTLFLAG_RW|CTLFLAG_VNET,
157 &VNET_NAME(tcp_pmtud_blackhole_detect), 0,
158 "Path MTU Discovery Black Hole Detection Enabled");
161 VNET_DEFINE(int, tcp_pmtud_blackhole_mss) = 1200;
162 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_mss,
163 CTLFLAG_RW|CTLFLAG_VNET,
164 &VNET_NAME(tcp_pmtud_blackhole_mss), 0,
165 "Path MTU Discovery Black Hole Detection lowered MSS");
169 VNET_DEFINE(int, tcp_v6pmtud_blackhole_mss) = 1220;
170 SYSCTL_INT(_net_inet_tcp, OID_AUTO, v6pmtud_blackhole_mss,
171 CTLFLAG_RW|CTLFLAG_VNET,
172 &VNET_NAME(tcp_v6pmtud_blackhole_mss), 0,
173 "Path MTU Discovery IPv6 Black Hole Detection lowered MSS");
177 static int per_cpu_timers = 1;
179 static int per_cpu_timers = 0;
181 SYSCTL_INT(_net_inet_tcp, OID_AUTO, per_cpu_timers, CTLFLAG_RW,
182 &per_cpu_timers , 0, "run tcp timers on all cpus");
185 * Map the given inp to a CPU id.
187 * This queries RSS if it's compiled in, else it defaults to the current
191 inp_to_cpuid(struct inpcb *inp)
196 if (per_cpu_timers) {
197 cpuid = rss_hash2cpuid(inp->inp_flowid, inp->inp_flowtype);
198 if (cpuid == NETISR_CPUID_NONE)
199 return (curcpu); /* XXX */
204 /* Legacy, pre-RSS behaviour */
205 if (per_cpu_timers) {
207 * We don't have a flowid -> cpuid mapping, so cheat and
208 * just map unknown cpuids to curcpu. Not the best, but
209 * apparently better than defaulting to swi 0.
211 cpuid = inp->inp_flowid % (mp_maxid + 1);
212 if (! CPU_ABSENT(cpuid))
217 /* Default for RSS and non-RSS - cpuid 0 */
224 * Tcp protocol timeout routine called every 500 ms.
225 * Updates timestamps used for TCP
226 * causes finite state machine actions if timers expire.
231 VNET_ITERATOR_DECL(vnet_iter);
233 VNET_LIST_RLOCK_NOSLEEP();
234 VNET_FOREACH(vnet_iter) {
235 CURVNET_SET(vnet_iter);
236 (void) tcp_tw_2msl_scan(0);
239 VNET_LIST_RUNLOCK_NOSLEEP();
242 int tcp_backoff[TCP_MAXRXTSHIFT + 1] =
243 { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 512, 512, 512 };
245 int tcp_totbackoff = 2559; /* sum of tcp_backoff[] */
248 * TCP timer processing.
252 tcp_timer_delack(void *xtp)
254 struct tcpcb *tp = xtp;
256 CURVNET_SET(tp->t_vnet);
259 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
261 if (callout_pending(&tp->t_timers->tt_delack) ||
262 !callout_active(&tp->t_timers->tt_delack)) {
267 callout_deactivate(&tp->t_timers->tt_delack);
268 if ((inp->inp_flags & INP_DROPPED) != 0) {
273 tp->t_flags |= TF_ACKNOW;
274 TCPSTAT_INC(tcps_delack);
275 (void) tp->t_fb->tfb_tcp_output(tp);
281 tcp_inpinfo_lock_del(struct inpcb *inp, struct tcpcb *tp)
283 if (inp && tp != NULL)
288 tcp_timer_2msl(void *xtp)
290 struct tcpcb *tp = xtp;
292 struct epoch_tracker et;
293 CURVNET_SET(tp->t_vnet);
297 ostate = tp->t_state;
300 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
302 tcp_free_sackholes(tp);
303 if (callout_pending(&tp->t_timers->tt_2msl) ||
304 !callout_active(&tp->t_timers->tt_2msl)) {
305 INP_WUNLOCK(tp->t_inpcb);
309 callout_deactivate(&tp->t_timers->tt_2msl);
310 if ((inp->inp_flags & INP_DROPPED) != 0) {
315 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
316 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
318 * 2 MSL timeout in shutdown went off. If we're closed but
319 * still waiting for peer to close and connection has been idle
320 * too long delete connection control block. Otherwise, check
323 * If in TIME_WAIT state just ignore as this timeout is handled in
324 * tcp_tw_2msl_scan().
326 * If fastrecycle of FIN_WAIT_2, in FIN_WAIT_2 and receiver has closed,
327 * there's no point in hanging onto FIN_WAIT_2 socket. Just close it.
328 * Ignore fact that there were recent incoming segments.
330 if ((inp->inp_flags & INP_TIMEWAIT) != 0) {
335 if (tcp_fast_finwait2_recycle && tp->t_state == TCPS_FIN_WAIT_2 &&
336 tp->t_inpcb && tp->t_inpcb->inp_socket &&
337 (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE)) {
338 TCPSTAT_INC(tcps_finwait2_drops);
339 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
340 tcp_inpinfo_lock_del(inp, tp);
343 INP_INFO_RLOCK_ET(&V_tcbinfo, et);
345 INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
346 tcp_inpinfo_lock_del(inp, tp);
349 if (ticks - tp->t_rcvtime <= TP_MAXIDLE(tp)) {
350 callout_reset(&tp->t_timers->tt_2msl,
351 TP_KEEPINTVL(tp), tcp_timer_2msl, tp);
353 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
354 tcp_inpinfo_lock_del(inp, tp);
357 INP_INFO_RLOCK_ET(&V_tcbinfo, et);
359 INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
360 tcp_inpinfo_lock_del(inp, tp);
366 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
367 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
370 TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
379 tcp_timer_keep(void *xtp)
381 struct tcpcb *tp = xtp;
382 struct tcptemp *t_template;
384 struct epoch_tracker et;
385 CURVNET_SET(tp->t_vnet);
389 ostate = tp->t_state;
392 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
394 if (callout_pending(&tp->t_timers->tt_keep) ||
395 !callout_active(&tp->t_timers->tt_keep)) {
400 callout_deactivate(&tp->t_timers->tt_keep);
401 if ((inp->inp_flags & INP_DROPPED) != 0) {
406 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
407 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
410 * Because we don't regularly reset the keepalive callout in
411 * the ESTABLISHED state, it may be that we don't actually need
412 * to send a keepalive yet. If that occurs, schedule another
413 * call for the next time the keepalive timer might expire.
415 if (TCPS_HAVEESTABLISHED(tp->t_state)) {
418 idletime = ticks - tp->t_rcvtime;
419 if (idletime < TP_KEEPIDLE(tp)) {
420 callout_reset(&tp->t_timers->tt_keep,
421 TP_KEEPIDLE(tp) - idletime, tcp_timer_keep, tp);
429 * Keep-alive timer went off; send something
430 * or drop connection if idle for too long.
432 TCPSTAT_INC(tcps_keeptimeo);
433 if (tp->t_state < TCPS_ESTABLISHED)
435 if ((V_tcp_always_keepalive ||
436 inp->inp_socket->so_options & SO_KEEPALIVE) &&
437 tp->t_state <= TCPS_CLOSING) {
438 if (ticks - tp->t_rcvtime >= TP_KEEPIDLE(tp) + TP_MAXIDLE(tp))
441 * Send a packet designed to force a response
442 * if the peer is up and reachable:
443 * either an ACK if the connection is still alive,
444 * or an RST if the peer has closed the connection
445 * due to timeout or reboot.
446 * Using sequence number tp->snd_una-1
447 * causes the transmitted zero-length segment
448 * to lie outside the receive window;
449 * by the protocol spec, this requires the
450 * correspondent TCP to respond.
452 TCPSTAT_INC(tcps_keepprobe);
453 t_template = tcpip_maketemplate(inp);
455 tcp_respond(tp, t_template->tt_ipgen,
456 &t_template->tt_t, (struct mbuf *)NULL,
457 tp->rcv_nxt, tp->snd_una - 1, 0);
458 free(t_template, M_TEMP);
460 callout_reset(&tp->t_timers->tt_keep, TP_KEEPINTVL(tp),
463 callout_reset(&tp->t_timers->tt_keep, TP_KEEPIDLE(tp),
467 if (inp->inp_socket->so_options & SO_DEBUG)
468 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
471 TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
477 TCPSTAT_INC(tcps_keepdrops);
478 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
479 tcp_inpinfo_lock_del(inp, tp);
482 INP_INFO_RLOCK_ET(&V_tcbinfo, et);
483 tp = tcp_drop(tp, ETIMEDOUT);
486 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
487 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
490 TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
491 INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
492 tcp_inpinfo_lock_del(inp, tp);
498 tcp_timer_persist(void *xtp)
500 struct tcpcb *tp = xtp;
502 struct epoch_tracker et;
503 CURVNET_SET(tp->t_vnet);
507 ostate = tp->t_state;
510 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
512 if (callout_pending(&tp->t_timers->tt_persist) ||
513 !callout_active(&tp->t_timers->tt_persist)) {
518 callout_deactivate(&tp->t_timers->tt_persist);
519 if ((inp->inp_flags & INP_DROPPED) != 0) {
524 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
525 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
527 * Persistence timer into zero window.
528 * Force a byte to be output, if possible.
530 TCPSTAT_INC(tcps_persisttimeo);
532 * Hack: if the peer is dead/unreachable, we do not
533 * time out if the window is closed. After a full
534 * backoff, drop the connection if the idle time
535 * (no responses to probes) reaches the maximum
536 * backoff that we would use if retransmitting.
538 if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
539 (ticks - tp->t_rcvtime >= tcp_maxpersistidle ||
540 ticks - tp->t_rcvtime >= TCP_REXMTVAL(tp) * tcp_totbackoff)) {
541 TCPSTAT_INC(tcps_persistdrop);
542 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
543 tcp_inpinfo_lock_del(inp, tp);
546 INP_INFO_RLOCK_ET(&V_tcbinfo, et);
547 tp = tcp_drop(tp, ETIMEDOUT);
548 INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
549 tcp_inpinfo_lock_del(inp, tp);
553 * If the user has closed the socket then drop a persisting
554 * connection after a much reduced timeout.
556 if (tp->t_state > TCPS_CLOSE_WAIT &&
557 (ticks - tp->t_rcvtime) >= TCPTV_PERSMAX) {
558 TCPSTAT_INC(tcps_persistdrop);
559 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
560 tcp_inpinfo_lock_del(inp, tp);
563 INP_INFO_RLOCK_ET(&V_tcbinfo, et);
564 tp = tcp_drop(tp, ETIMEDOUT);
565 INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
566 tcp_inpinfo_lock_del(inp, tp);
570 tp->t_flags |= TF_FORCEDATA;
571 (void) tp->t_fb->tfb_tcp_output(tp);
572 tp->t_flags &= ~TF_FORCEDATA;
575 if (tp != NULL && tp->t_inpcb->inp_socket->so_options & SO_DEBUG)
576 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO);
578 TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
585 tcp_timer_rexmt(void * xtp)
587 struct tcpcb *tp = xtp;
588 CURVNET_SET(tp->t_vnet);
591 struct epoch_tracker et;
596 ostate = tp->t_state;
599 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
601 if (callout_pending(&tp->t_timers->tt_rexmt) ||
602 !callout_active(&tp->t_timers->tt_rexmt)) {
607 callout_deactivate(&tp->t_timers->tt_rexmt);
608 if ((inp->inp_flags & INP_DROPPED) != 0) {
613 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
614 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
615 tcp_free_sackholes(tp);
616 TCP_LOG_EVENT(tp, NULL, NULL, NULL, TCP_LOG_RTO, 0, 0, NULL, false);
617 if (tp->t_fb->tfb_tcp_rexmit_tmr) {
618 /* The stack has a timer action too. */
619 (*tp->t_fb->tfb_tcp_rexmit_tmr)(tp);
622 * Retransmission timer went off. Message has not
623 * been acked within retransmit interval. Back off
624 * to a longer retransmit interval and retransmit one segment.
626 if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) {
627 tp->t_rxtshift = TCP_MAXRXTSHIFT;
628 TCPSTAT_INC(tcps_timeoutdrop);
629 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
630 tcp_inpinfo_lock_del(inp, tp);
633 INP_INFO_RLOCK_ET(&V_tcbinfo, et);
634 tp = tcp_drop(tp, ETIMEDOUT);
635 INP_INFO_RUNLOCK_ET(&V_tcbinfo, et);
636 tcp_inpinfo_lock_del(inp, tp);
639 if (tp->t_state == TCPS_SYN_SENT) {
641 * If the SYN was retransmitted, indicate CWND to be
642 * limited to 1 segment in cc_conn_init().
645 } else if (tp->t_rxtshift == 1) {
647 * first retransmit; record ssthresh and cwnd so they can
648 * be recovered if this turns out to be a "bad" retransmit.
649 * A retransmit is considered "bad" if an ACK for this
650 * segment is received within RTT/2 interval; the assumption
651 * here is that the ACK was already in flight. See
652 * "On Estimating End-to-End Network Path Properties" by
653 * Allman and Paxson for more details.
655 tp->snd_cwnd_prev = tp->snd_cwnd;
656 tp->snd_ssthresh_prev = tp->snd_ssthresh;
657 tp->snd_recover_prev = tp->snd_recover;
658 if (IN_FASTRECOVERY(tp->t_flags))
659 tp->t_flags |= TF_WASFRECOVERY;
661 tp->t_flags &= ~TF_WASFRECOVERY;
662 if (IN_CONGRECOVERY(tp->t_flags))
663 tp->t_flags |= TF_WASCRECOVERY;
665 tp->t_flags &= ~TF_WASCRECOVERY;
666 if ((tp->t_flags & TF_RCVD_TSTMP) == 0)
667 tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1));
668 /* In the event that we've negotiated timestamps
669 * badrxtwin will be set to the value that we set
670 * the retransmitted packet's to_tsval to by tcp_output
672 tp->t_flags |= TF_PREVVALID;
674 tp->t_flags &= ~TF_PREVVALID;
675 TCPSTAT_INC(tcps_rexmttimeo);
676 if ((tp->t_state == TCPS_SYN_SENT) ||
677 (tp->t_state == TCPS_SYN_RECEIVED))
678 rexmt = tcp_rexmit_initial * tcp_backoff[tp->t_rxtshift];
680 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
681 TCPT_RANGESET(tp->t_rxtcur, rexmt,
682 tp->t_rttmin, TCPTV_REXMTMAX);
685 * We enter the path for PLMTUD if connection is established or, if
686 * connection is FIN_WAIT_1 status, reason for the last is that if
687 * amount of data we send is very small, we could send it in couple of
688 * packets and process straight to FIN. In that case we won't catch
692 isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) ? true : false;
696 if (((V_tcp_pmtud_blackhole_detect == 1) ||
697 (V_tcp_pmtud_blackhole_detect == 2 && !isipv6) ||
698 (V_tcp_pmtud_blackhole_detect == 3 && isipv6)) &&
699 ((tp->t_state == TCPS_ESTABLISHED) ||
700 (tp->t_state == TCPS_FIN_WAIT_1))) {
701 if (tp->t_rxtshift == 1) {
703 * We enter blackhole detection after the first
704 * unsuccessful timer based retransmission.
705 * Then we reduce up to two times the MSS, each
706 * candidate giving two tries of retransmissions.
707 * But we give a candidate only two tries, if it
708 * actually reduces the MSS.
710 tp->t_blackhole_enter = 2;
711 tp->t_blackhole_exit = tp->t_blackhole_enter;
714 if (tp->t_maxseg > V_tcp_v6pmtud_blackhole_mss)
715 tp->t_blackhole_exit += 2;
716 if (tp->t_maxseg > V_tcp_v6mssdflt &&
717 V_tcp_v6pmtud_blackhole_mss > V_tcp_v6mssdflt)
718 tp->t_blackhole_exit += 2;
722 if (tp->t_maxseg > V_tcp_pmtud_blackhole_mss)
723 tp->t_blackhole_exit += 2;
724 if (tp->t_maxseg > V_tcp_mssdflt &&
725 V_tcp_pmtud_blackhole_mss > V_tcp_mssdflt)
726 tp->t_blackhole_exit += 2;
730 if (((tp->t_flags2 & (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) ==
731 (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) &&
732 (tp->t_rxtshift >= tp->t_blackhole_enter &&
733 tp->t_rxtshift < tp->t_blackhole_exit &&
734 (tp->t_rxtshift - tp->t_blackhole_enter) % 2 == 0)) {
736 * Enter Path MTU Black-hole Detection mechanism:
737 * - Disable Path MTU Discovery (IP "DF" bit).
738 * - Reduce MTU to lower value than what we
739 * negotiated with peer.
741 if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) == 0) {
742 /* Record that we may have found a black hole. */
743 tp->t_flags2 |= TF2_PLPMTU_BLACKHOLE;
744 /* Keep track of previous MSS. */
745 tp->t_pmtud_saved_maxseg = tp->t_maxseg;
749 * Reduce the MSS to blackhole value or to the default
750 * in an attempt to retransmit.
754 tp->t_maxseg > V_tcp_v6pmtud_blackhole_mss &&
755 V_tcp_v6pmtud_blackhole_mss > V_tcp_v6mssdflt) {
756 /* Use the sysctl tuneable blackhole MSS. */
757 tp->t_maxseg = V_tcp_v6pmtud_blackhole_mss;
758 TCPSTAT_INC(tcps_pmtud_blackhole_activated);
760 /* Use the default MSS. */
761 tp->t_maxseg = V_tcp_v6mssdflt;
763 * Disable Path MTU Discovery when we switch to
766 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
767 TCPSTAT_INC(tcps_pmtud_blackhole_activated_min_mss);
770 #if defined(INET6) && defined(INET)
774 if (tp->t_maxseg > V_tcp_pmtud_blackhole_mss &&
775 V_tcp_pmtud_blackhole_mss > V_tcp_mssdflt) {
776 /* Use the sysctl tuneable blackhole MSS. */
777 tp->t_maxseg = V_tcp_pmtud_blackhole_mss;
778 TCPSTAT_INC(tcps_pmtud_blackhole_activated);
780 /* Use the default MSS. */
781 tp->t_maxseg = V_tcp_mssdflt;
783 * Disable Path MTU Discovery when we switch to
786 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
787 TCPSTAT_INC(tcps_pmtud_blackhole_activated_min_mss);
791 * Reset the slow-start flight size
792 * as it may depend on the new MSS.
794 if (CC_ALGO(tp)->conn_init != NULL)
795 CC_ALGO(tp)->conn_init(tp->ccv);
798 * If further retransmissions are still unsuccessful
799 * with a lowered MTU, maybe this isn't a blackhole and
800 * we restore the previous MSS and blackhole detection
803 if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) &&
804 (tp->t_rxtshift >= tp->t_blackhole_exit)) {
805 tp->t_flags2 |= TF2_PLPMTU_PMTUD;
806 tp->t_flags2 &= ~TF2_PLPMTU_BLACKHOLE;
807 tp->t_maxseg = tp->t_pmtud_saved_maxseg;
808 TCPSTAT_INC(tcps_pmtud_blackhole_failed);
810 * Reset the slow-start flight size as it
811 * may depend on the new MSS.
813 if (CC_ALGO(tp)->conn_init != NULL)
814 CC_ALGO(tp)->conn_init(tp->ccv);
820 * Disable RFC1323 and SACK if we haven't got any response to
821 * our third SYN to work-around some broken terminal servers
822 * (most of which have hopefully been retired) that have bad VJ
823 * header compression code which trashes TCP segments containing
824 * unknown-to-them TCP options.
826 if (tcp_rexmit_drop_options && (tp->t_state == TCPS_SYN_SENT) &&
827 (tp->t_rxtshift == 3))
828 tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP|TF_SACK_PERMIT);
830 * If we backed off this far, notify the L3 protocol that we're having
831 * connection problems.
833 if (tp->t_rxtshift > TCP_RTT_INVALIDATE) {
835 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0)
836 in6_losing(tp->t_inpcb);
839 in_losing(tp->t_inpcb);
841 tp->snd_nxt = tp->snd_una;
842 tp->snd_recover = tp->snd_max;
844 * Force a segment to be sent.
846 tp->t_flags |= TF_ACKNOW;
848 * If timing a segment in this window, stop the timer.
852 cc_cong_signal(tp, NULL, CC_RTO);
854 (void) tp->t_fb->tfb_tcp_output(tp);
857 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
858 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
861 TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
868 tcp_timer_activate(struct tcpcb *tp, uint32_t timer_type, u_int delta)
870 struct callout *t_callout;
871 timeout_t *f_callout;
872 struct inpcb *inp = tp->t_inpcb;
873 int cpu = inp_to_cpuid(inp);
876 if (tp->t_flags & TF_TOE)
880 if (tp->t_timers->tt_flags & TT_STOPPED)
883 switch (timer_type) {
885 t_callout = &tp->t_timers->tt_delack;
886 f_callout = tcp_timer_delack;
889 t_callout = &tp->t_timers->tt_rexmt;
890 f_callout = tcp_timer_rexmt;
893 t_callout = &tp->t_timers->tt_persist;
894 f_callout = tcp_timer_persist;
897 t_callout = &tp->t_timers->tt_keep;
898 f_callout = tcp_timer_keep;
901 t_callout = &tp->t_timers->tt_2msl;
902 f_callout = tcp_timer_2msl;
905 if (tp->t_fb->tfb_tcp_timer_activate) {
906 tp->t_fb->tfb_tcp_timer_activate(tp, timer_type, delta);
909 panic("tp %p bad timer_type %#x", tp, timer_type);
912 callout_stop(t_callout);
914 callout_reset_on(t_callout, delta, f_callout, tp, cpu);
919 tcp_timer_active(struct tcpcb *tp, uint32_t timer_type)
921 struct callout *t_callout;
923 switch (timer_type) {
925 t_callout = &tp->t_timers->tt_delack;
928 t_callout = &tp->t_timers->tt_rexmt;
931 t_callout = &tp->t_timers->tt_persist;
934 t_callout = &tp->t_timers->tt_keep;
937 t_callout = &tp->t_timers->tt_2msl;
940 if (tp->t_fb->tfb_tcp_timer_active) {
941 return(tp->t_fb->tfb_tcp_timer_active(tp, timer_type));
943 panic("tp %p bad timer_type %#x", tp, timer_type);
945 return callout_active(t_callout);
949 * Stop the timer from running, and apply a flag
950 * against the timer_flags that will force the
951 * timer never to run. The flag is needed to assure
952 * a race does not leave it running and cause
953 * the timer to possibly restart itself (keep and persist
954 * especially do this).
957 tcp_timer_suspend(struct tcpcb *tp, uint32_t timer_type)
959 struct callout *t_callout;
962 switch (timer_type) {
964 t_flags = TT_DELACK_SUS;
965 t_callout = &tp->t_timers->tt_delack;
968 t_flags = TT_REXMT_SUS;
969 t_callout = &tp->t_timers->tt_rexmt;
972 t_flags = TT_PERSIST_SUS;
973 t_callout = &tp->t_timers->tt_persist;
976 t_flags = TT_KEEP_SUS;
977 t_callout = &tp->t_timers->tt_keep;
980 t_flags = TT_2MSL_SUS;
981 t_callout = &tp->t_timers->tt_2msl;
984 panic("tp:%p bad timer_type 0x%x", tp, timer_type);
986 tp->t_timers->tt_flags |= t_flags;
987 return (callout_stop(t_callout));
991 tcp_timers_unsuspend(struct tcpcb *tp, uint32_t timer_type)
993 switch (timer_type) {
995 if (tp->t_timers->tt_flags & TT_DELACK_SUS) {
996 tp->t_timers->tt_flags &= ~TT_DELACK_SUS;
997 if (tp->t_flags & TF_DELACK) {
998 /* Delayed ack timer should be up activate a timer */
999 tp->t_flags &= ~TF_DELACK;
1000 tcp_timer_activate(tp, TT_DELACK,
1006 if (tp->t_timers->tt_flags & TT_REXMT_SUS) {
1007 tp->t_timers->tt_flags &= ~TT_REXMT_SUS;
1008 if (SEQ_GT(tp->snd_max, tp->snd_una) &&
1009 (tcp_timer_active((tp), TT_PERSIST) == 0) &&
1011 /* We have outstanding data activate a timer */
1012 tcp_timer_activate(tp, TT_REXMT,
1018 if (tp->t_timers->tt_flags & TT_PERSIST_SUS) {
1019 tp->t_timers->tt_flags &= ~TT_PERSIST_SUS;
1020 if (tp->snd_wnd == 0) {
1021 /* Activate the persists timer */
1028 if (tp->t_timers->tt_flags & TT_KEEP_SUS) {
1029 tp->t_timers->tt_flags &= ~TT_KEEP_SUS;
1030 tcp_timer_activate(tp, TT_KEEP,
1031 TCPS_HAVEESTABLISHED(tp->t_state) ?
1032 TP_KEEPIDLE(tp) : TP_KEEPINIT(tp));
1036 if (tp->t_timers->tt_flags &= TT_2MSL_SUS) {
1037 tp->t_timers->tt_flags &= ~TT_2MSL_SUS;
1038 if ((tp->t_state == TCPS_FIN_WAIT_2) &&
1039 ((tp->t_inpcb->inp_socket == NULL) ||
1040 (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE))) {
1041 /* Star the 2MSL timer */
1042 tcp_timer_activate(tp, TT_2MSL,
1043 (tcp_fast_finwait2_recycle) ?
1044 tcp_finwait2_timeout : TP_MAXIDLE(tp));
1049 panic("tp:%p bad timer_type 0x%x", tp, timer_type);
1054 tcp_timer_stop(struct tcpcb *tp, uint32_t timer_type)
1056 struct callout *t_callout;
1058 tp->t_timers->tt_flags |= TT_STOPPED;
1059 switch (timer_type) {
1061 t_callout = &tp->t_timers->tt_delack;
1064 t_callout = &tp->t_timers->tt_rexmt;
1067 t_callout = &tp->t_timers->tt_persist;
1070 t_callout = &tp->t_timers->tt_keep;
1073 t_callout = &tp->t_timers->tt_2msl;
1076 if (tp->t_fb->tfb_tcp_timer_stop) {
1078 * XXXrrs we need to look at this with the
1079 * stop case below (flags).
1081 tp->t_fb->tfb_tcp_timer_stop(tp, timer_type);
1084 panic("tp %p bad timer_type %#x", tp, timer_type);
1087 if (callout_async_drain(t_callout, tcp_timer_discard) == 0) {
1089 * Can't stop the callout, defer tcpcb actual deletion
1090 * to the last one. We do this using the async drain
1091 * function and incrementing the count in
1093 tp->t_timers->tt_draincnt++;