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.
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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);
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);
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);
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);
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);
547 tp = tcp_drop(tp, ETIMEDOUT);
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);
564 tp = tcp_drop(tp, ETIMEDOUT);
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;
595 ostate = tp->t_state;
598 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
600 if (callout_pending(&tp->t_timers->tt_rexmt) ||
601 !callout_active(&tp->t_timers->tt_rexmt)) {
606 callout_deactivate(&tp->t_timers->tt_rexmt);
607 if ((inp->inp_flags & INP_DROPPED) != 0) {
612 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
613 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
614 tcp_free_sackholes(tp);
615 TCP_LOG_EVENT(tp, NULL, NULL, NULL, TCP_LOG_RTO, 0, 0, NULL, false);
616 if (tp->t_fb->tfb_tcp_rexmit_tmr) {
617 /* The stack has a timer action too. */
618 (*tp->t_fb->tfb_tcp_rexmit_tmr)(tp);
621 * Retransmission timer went off. Message has not
622 * been acked within retransmit interval. Back off
623 * to a longer retransmit interval and retransmit one segment.
625 if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) {
626 tp->t_rxtshift = TCP_MAXRXTSHIFT;
627 TCPSTAT_INC(tcps_timeoutdrop);
628 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
629 tcp_inpinfo_lock_del(inp, tp);
633 tp = tcp_drop(tp, ETIMEDOUT);
635 tcp_inpinfo_lock_del(inp, tp);
638 if (tp->t_state == TCPS_SYN_SENT) {
640 * If the SYN was retransmitted, indicate CWND to be
641 * limited to 1 segment in cc_conn_init().
644 } else if (tp->t_rxtshift == 1) {
646 * first retransmit; record ssthresh and cwnd so they can
647 * be recovered if this turns out to be a "bad" retransmit.
648 * A retransmit is considered "bad" if an ACK for this
649 * segment is received within RTT/2 interval; the assumption
650 * here is that the ACK was already in flight. See
651 * "On Estimating End-to-End Network Path Properties" by
652 * Allman and Paxson for more details.
654 tp->snd_cwnd_prev = tp->snd_cwnd;
655 tp->snd_ssthresh_prev = tp->snd_ssthresh;
656 tp->snd_recover_prev = tp->snd_recover;
657 if (IN_FASTRECOVERY(tp->t_flags))
658 tp->t_flags |= TF_WASFRECOVERY;
660 tp->t_flags &= ~TF_WASFRECOVERY;
661 if (IN_CONGRECOVERY(tp->t_flags))
662 tp->t_flags |= TF_WASCRECOVERY;
664 tp->t_flags &= ~TF_WASCRECOVERY;
665 if ((tp->t_flags & TF_RCVD_TSTMP) == 0)
666 tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1));
667 /* In the event that we've negotiated timestamps
668 * badrxtwin will be set to the value that we set
669 * the retransmitted packet's to_tsval to by tcp_output
671 tp->t_flags |= TF_PREVVALID;
673 tp->t_flags &= ~TF_PREVVALID;
674 TCPSTAT_INC(tcps_rexmttimeo);
675 if ((tp->t_state == TCPS_SYN_SENT) ||
676 (tp->t_state == TCPS_SYN_RECEIVED))
677 rexmt = tcp_rexmit_initial * tcp_backoff[tp->t_rxtshift];
679 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
680 TCPT_RANGESET(tp->t_rxtcur, rexmt,
681 tp->t_rttmin, TCPTV_REXMTMAX);
684 * We enter the path for PLMTUD if connection is established or, if
685 * connection is FIN_WAIT_1 status, reason for the last is that if
686 * amount of data we send is very small, we could send it in couple of
687 * packets and process straight to FIN. In that case we won't catch
690 if (V_tcp_pmtud_blackhole_detect && (((tp->t_state == TCPS_ESTABLISHED))
691 || (tp->t_state == TCPS_FIN_WAIT_1))) {
697 * Idea here is that at each stage of mtu probe (usually, 1448
698 * -> 1188 -> 524) should be given 2 chances to recover before
699 * further clamping down. 'tp->t_rxtshift % 2 == 0' should
702 if (((tp->t_flags2 & (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) ==
703 (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) &&
704 (tp->t_rxtshift >= 2 && tp->t_rxtshift < 6 &&
705 tp->t_rxtshift % 2 == 0)) {
707 * Enter Path MTU Black-hole Detection mechanism:
708 * - Disable Path MTU Discovery (IP "DF" bit).
709 * - Reduce MTU to lower value than what we
710 * negotiated with peer.
712 if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) == 0) {
713 /* Record that we may have found a black hole. */
714 tp->t_flags2 |= TF2_PLPMTU_BLACKHOLE;
715 /* Keep track of previous MSS. */
716 tp->t_pmtud_saved_maxseg = tp->t_maxseg;
720 * Reduce the MSS to blackhole value or to the default
721 * in an attempt to retransmit.
724 isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) ? 1 : 0;
726 tp->t_maxseg > V_tcp_v6pmtud_blackhole_mss) {
727 /* Use the sysctl tuneable blackhole MSS. */
728 tp->t_maxseg = V_tcp_v6pmtud_blackhole_mss;
729 TCPSTAT_INC(tcps_pmtud_blackhole_activated);
731 /* Use the default MSS. */
732 tp->t_maxseg = V_tcp_v6mssdflt;
734 * Disable Path MTU Discovery when we switch to
737 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
738 TCPSTAT_INC(tcps_pmtud_blackhole_activated_min_mss);
741 #if defined(INET6) && defined(INET)
745 if (tp->t_maxseg > V_tcp_pmtud_blackhole_mss) {
746 /* Use the sysctl tuneable blackhole MSS. */
747 tp->t_maxseg = V_tcp_pmtud_blackhole_mss;
748 TCPSTAT_INC(tcps_pmtud_blackhole_activated);
750 /* Use the default MSS. */
751 tp->t_maxseg = V_tcp_mssdflt;
753 * Disable Path MTU Discovery when we switch to
756 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
757 TCPSTAT_INC(tcps_pmtud_blackhole_activated_min_mss);
761 * Reset the slow-start flight size
762 * as it may depend on the new MSS.
764 if (CC_ALGO(tp)->conn_init != NULL)
765 CC_ALGO(tp)->conn_init(tp->ccv);
768 * If further retransmissions are still unsuccessful
769 * with a lowered MTU, maybe this isn't a blackhole and
770 * we restore the previous MSS and blackhole detection
772 * The limit '6' is determined by giving each probe
773 * stage (1448, 1188, 524) 2 chances to recover.
775 if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) &&
776 (tp->t_rxtshift >= 6)) {
777 tp->t_flags2 |= TF2_PLPMTU_PMTUD;
778 tp->t_flags2 &= ~TF2_PLPMTU_BLACKHOLE;
779 tp->t_maxseg = tp->t_pmtud_saved_maxseg;
780 TCPSTAT_INC(tcps_pmtud_blackhole_failed);
782 * Reset the slow-start flight size as it
783 * may depend on the new MSS.
785 if (CC_ALGO(tp)->conn_init != NULL)
786 CC_ALGO(tp)->conn_init(tp->ccv);
792 * Disable RFC1323 and SACK if we haven't got any response to
793 * our third SYN to work-around some broken terminal servers
794 * (most of which have hopefully been retired) that have bad VJ
795 * header compression code which trashes TCP segments containing
796 * unknown-to-them TCP options.
798 if (tcp_rexmit_drop_options && (tp->t_state == TCPS_SYN_SENT) &&
799 (tp->t_rxtshift == 3))
800 tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP|TF_SACK_PERMIT);
802 * If we backed off this far, notify the L3 protocol that we're having
803 * connection problems.
805 if (tp->t_rxtshift > TCP_RTT_INVALIDATE) {
807 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0)
808 in6_losing(tp->t_inpcb);
811 in_losing(tp->t_inpcb);
813 tp->snd_nxt = tp->snd_una;
814 tp->snd_recover = tp->snd_max;
816 * Force a segment to be sent.
818 tp->t_flags |= TF_ACKNOW;
820 * If timing a segment in this window, stop the timer.
824 cc_cong_signal(tp, NULL, CC_RTO);
826 (void) tp->t_fb->tfb_tcp_output(tp);
829 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
830 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
833 TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
840 tcp_timer_activate(struct tcpcb *tp, uint32_t timer_type, u_int delta)
842 struct callout *t_callout;
843 callout_func_t *f_callout;
844 struct inpcb *inp = tp->t_inpcb;
845 int cpu = inp_to_cpuid(inp);
848 if (tp->t_flags & TF_TOE)
852 if (tp->t_timers->tt_flags & TT_STOPPED)
855 switch (timer_type) {
857 t_callout = &tp->t_timers->tt_delack;
858 f_callout = tcp_timer_delack;
861 t_callout = &tp->t_timers->tt_rexmt;
862 f_callout = tcp_timer_rexmt;
865 t_callout = &tp->t_timers->tt_persist;
866 f_callout = tcp_timer_persist;
869 t_callout = &tp->t_timers->tt_keep;
870 f_callout = tcp_timer_keep;
873 t_callout = &tp->t_timers->tt_2msl;
874 f_callout = tcp_timer_2msl;
877 if (tp->t_fb->tfb_tcp_timer_activate) {
878 tp->t_fb->tfb_tcp_timer_activate(tp, timer_type, delta);
881 panic("tp %p bad timer_type %#x", tp, timer_type);
884 callout_stop(t_callout);
886 callout_reset_on(t_callout, delta, f_callout, tp, cpu);
891 tcp_timer_active(struct tcpcb *tp, uint32_t timer_type)
893 struct callout *t_callout;
895 switch (timer_type) {
897 t_callout = &tp->t_timers->tt_delack;
900 t_callout = &tp->t_timers->tt_rexmt;
903 t_callout = &tp->t_timers->tt_persist;
906 t_callout = &tp->t_timers->tt_keep;
909 t_callout = &tp->t_timers->tt_2msl;
912 if (tp->t_fb->tfb_tcp_timer_active) {
913 return(tp->t_fb->tfb_tcp_timer_active(tp, timer_type));
915 panic("tp %p bad timer_type %#x", tp, timer_type);
917 return callout_active(t_callout);
921 * Stop the timer from running, and apply a flag
922 * against the timer_flags that will force the
923 * timer never to run. The flag is needed to assure
924 * a race does not leave it running and cause
925 * the timer to possibly restart itself (keep and persist
926 * especially do this).
929 tcp_timer_suspend(struct tcpcb *tp, uint32_t timer_type)
931 struct callout *t_callout;
934 switch (timer_type) {
936 t_flags = TT_DELACK_SUS;
937 t_callout = &tp->t_timers->tt_delack;
940 t_flags = TT_REXMT_SUS;
941 t_callout = &tp->t_timers->tt_rexmt;
944 t_flags = TT_PERSIST_SUS;
945 t_callout = &tp->t_timers->tt_persist;
948 t_flags = TT_KEEP_SUS;
949 t_callout = &tp->t_timers->tt_keep;
952 t_flags = TT_2MSL_SUS;
953 t_callout = &tp->t_timers->tt_2msl;
956 panic("tp:%p bad timer_type 0x%x", tp, timer_type);
958 tp->t_timers->tt_flags |= t_flags;
959 return (callout_stop(t_callout));
963 tcp_timers_unsuspend(struct tcpcb *tp, uint32_t timer_type)
965 switch (timer_type) {
967 if (tp->t_timers->tt_flags & TT_DELACK_SUS) {
968 tp->t_timers->tt_flags &= ~TT_DELACK_SUS;
969 if (tp->t_flags & TF_DELACK) {
970 /* Delayed ack timer should be up activate a timer */
971 tp->t_flags &= ~TF_DELACK;
972 tcp_timer_activate(tp, TT_DELACK,
978 if (tp->t_timers->tt_flags & TT_REXMT_SUS) {
979 tp->t_timers->tt_flags &= ~TT_REXMT_SUS;
980 if (SEQ_GT(tp->snd_max, tp->snd_una) &&
981 (tcp_timer_active((tp), TT_PERSIST) == 0) &&
983 /* We have outstanding data activate a timer */
984 tcp_timer_activate(tp, TT_REXMT,
990 if (tp->t_timers->tt_flags & TT_PERSIST_SUS) {
991 tp->t_timers->tt_flags &= ~TT_PERSIST_SUS;
992 if (tp->snd_wnd == 0) {
993 /* Activate the persists timer */
1000 if (tp->t_timers->tt_flags & TT_KEEP_SUS) {
1001 tp->t_timers->tt_flags &= ~TT_KEEP_SUS;
1002 tcp_timer_activate(tp, TT_KEEP,
1003 TCPS_HAVEESTABLISHED(tp->t_state) ?
1004 TP_KEEPIDLE(tp) : TP_KEEPINIT(tp));
1008 if (tp->t_timers->tt_flags &= TT_2MSL_SUS) {
1009 tp->t_timers->tt_flags &= ~TT_2MSL_SUS;
1010 if ((tp->t_state == TCPS_FIN_WAIT_2) &&
1011 ((tp->t_inpcb->inp_socket == NULL) ||
1012 (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE))) {
1013 /* Star the 2MSL timer */
1014 tcp_timer_activate(tp, TT_2MSL,
1015 (tcp_fast_finwait2_recycle) ?
1016 tcp_finwait2_timeout : TP_MAXIDLE(tp));
1021 panic("tp:%p bad timer_type 0x%x", tp, timer_type);
1026 tcp_timer_stop(struct tcpcb *tp, uint32_t timer_type)
1028 struct callout *t_callout;
1030 tp->t_timers->tt_flags |= TT_STOPPED;
1031 switch (timer_type) {
1033 t_callout = &tp->t_timers->tt_delack;
1036 t_callout = &tp->t_timers->tt_rexmt;
1039 t_callout = &tp->t_timers->tt_persist;
1042 t_callout = &tp->t_timers->tt_keep;
1045 t_callout = &tp->t_timers->tt_2msl;
1048 if (tp->t_fb->tfb_tcp_timer_stop) {
1050 * XXXrrs we need to look at this with the
1051 * stop case below (flags).
1053 tp->t_fb->tfb_tcp_timer_stop(tp, timer_type);
1056 panic("tp %p bad timer_type %#x", tp, timer_type);
1059 if (callout_async_drain(t_callout, tcp_timer_discard) == 0) {
1061 * Can't stop the callout, defer tcpcb actual deletion
1062 * to the last one. We do this using the async drain
1063 * function and incrementing the count in
1065 tp->t_timers->tt_draincnt++;