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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11 * notice, this list of conditions and the following disclaimer.
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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,
86 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
87 &tcp_persmin, 0, sysctl_msec_to_ticks, "I",
88 "minimum persistence interval");
91 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, persmax,
92 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
93 &tcp_persmax, 0, sysctl_msec_to_ticks, "I",
94 "maximum persistence interval");
97 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit,
98 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
99 &tcp_keepinit, 0, sysctl_msec_to_ticks, "I",
100 "time to establish connection");
103 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle,
104 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
105 &tcp_keepidle, 0, sysctl_msec_to_ticks, "I",
106 "time before keepalive probes begin");
109 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl,
110 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
111 &tcp_keepintvl, 0, sysctl_msec_to_ticks, "I",
112 "time between keepalive probes");
115 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DELACKTIME, delacktime,
116 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
117 &tcp_delacktime, 0, sysctl_msec_to_ticks, "I",
118 "Time before a delayed ACK is sent");
121 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl,
122 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
123 &tcp_msl, 0, sysctl_msec_to_ticks, "I",
124 "Maximum segment lifetime");
126 int tcp_rexmit_initial;
127 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_initial,
128 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
129 &tcp_rexmit_initial, 0, sysctl_msec_to_ticks, "I",
130 "Initial Retransmission Timeout");
133 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_min,
134 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
135 &tcp_rexmit_min, 0, sysctl_msec_to_ticks, "I",
136 "Minimum Retransmission Timeout");
139 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_slop,
140 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
141 &tcp_rexmit_slop, 0, sysctl_msec_to_ticks, "I",
142 "Retransmission Timer Slop");
144 VNET_DEFINE(int, tcp_always_keepalive) = 1;
145 SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive, CTLFLAG_VNET|CTLFLAG_RW,
146 &VNET_NAME(tcp_always_keepalive) , 0,
147 "Assume SO_KEEPALIVE on all TCP connections");
149 int tcp_fast_finwait2_recycle = 0;
150 SYSCTL_INT(_net_inet_tcp, OID_AUTO, fast_finwait2_recycle, CTLFLAG_RW,
151 &tcp_fast_finwait2_recycle, 0,
152 "Recycle closed FIN_WAIT_2 connections faster");
154 int tcp_finwait2_timeout;
155 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, finwait2_timeout,
156 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
157 &tcp_finwait2_timeout, 0, sysctl_msec_to_ticks, "I",
158 "FIN-WAIT2 timeout");
160 int tcp_keepcnt = TCPTV_KEEPCNT;
161 SYSCTL_INT(_net_inet_tcp, OID_AUTO, keepcnt, CTLFLAG_RW, &tcp_keepcnt, 0,
162 "Number of keepalive probes to send");
164 /* max idle probes */
165 int tcp_maxpersistidle;
167 int tcp_rexmit_drop_options = 0;
168 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rexmit_drop_options, CTLFLAG_RW,
169 &tcp_rexmit_drop_options, 0,
170 "Drop TCP options from 3rd and later retransmitted SYN");
172 VNET_DEFINE(int, tcp_pmtud_blackhole_detect);
173 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_detection,
174 CTLFLAG_RW|CTLFLAG_VNET,
175 &VNET_NAME(tcp_pmtud_blackhole_detect), 0,
176 "Path MTU Discovery Black Hole Detection Enabled");
179 VNET_DEFINE(int, tcp_pmtud_blackhole_mss) = 1200;
180 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_mss,
181 CTLFLAG_RW|CTLFLAG_VNET,
182 &VNET_NAME(tcp_pmtud_blackhole_mss), 0,
183 "Path MTU Discovery Black Hole Detection lowered MSS");
187 VNET_DEFINE(int, tcp_v6pmtud_blackhole_mss) = 1220;
188 SYSCTL_INT(_net_inet_tcp, OID_AUTO, v6pmtud_blackhole_mss,
189 CTLFLAG_RW|CTLFLAG_VNET,
190 &VNET_NAME(tcp_v6pmtud_blackhole_mss), 0,
191 "Path MTU Discovery IPv6 Black Hole Detection lowered MSS");
195 static int per_cpu_timers = 1;
197 static int per_cpu_timers = 0;
199 SYSCTL_INT(_net_inet_tcp, OID_AUTO, per_cpu_timers, CTLFLAG_RW,
200 &per_cpu_timers , 0, "run tcp timers on all cpus");
203 * Map the given inp to a CPU id.
205 * This queries RSS if it's compiled in, else it defaults to the current
209 inp_to_cpuid(struct inpcb *inp)
214 if (per_cpu_timers) {
215 cpuid = rss_hash2cpuid(inp->inp_flowid, inp->inp_flowtype);
216 if (cpuid == NETISR_CPUID_NONE)
217 return (curcpu); /* XXX */
222 /* Legacy, pre-RSS behaviour */
223 if (per_cpu_timers) {
225 * We don't have a flowid -> cpuid mapping, so cheat and
226 * just map unknown cpuids to curcpu. Not the best, but
227 * apparently better than defaulting to swi 0.
229 cpuid = inp->inp_flowid % (mp_maxid + 1);
230 if (! CPU_ABSENT(cpuid))
235 /* Default for RSS and non-RSS - cpuid 0 */
242 * Tcp protocol timeout routine called every 500 ms.
243 * Updates timestamps used for TCP
244 * causes finite state machine actions if timers expire.
249 VNET_ITERATOR_DECL(vnet_iter);
251 VNET_LIST_RLOCK_NOSLEEP();
252 VNET_FOREACH(vnet_iter) {
253 CURVNET_SET(vnet_iter);
254 (void) tcp_tw_2msl_scan(0);
257 VNET_LIST_RUNLOCK_NOSLEEP();
260 int tcp_backoff[TCP_MAXRXTSHIFT + 1] =
261 { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 512, 512, 512 };
263 int tcp_totbackoff = 2559; /* sum of tcp_backoff[] */
266 * TCP timer processing.
270 tcp_timer_delack(void *xtp)
272 struct epoch_tracker et;
273 struct tcpcb *tp = xtp;
275 CURVNET_SET(tp->t_vnet);
278 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
280 if (callout_pending(&tp->t_timers->tt_delack) ||
281 !callout_active(&tp->t_timers->tt_delack)) {
286 callout_deactivate(&tp->t_timers->tt_delack);
287 if ((inp->inp_flags & INP_DROPPED) != 0) {
292 tp->t_flags |= TF_ACKNOW;
293 TCPSTAT_INC(tcps_delack);
295 (void) tp->t_fb->tfb_tcp_output(tp);
302 tcp_inpinfo_lock_del(struct inpcb *inp, struct tcpcb *tp)
304 if (inp && tp != NULL)
309 tcp_timer_2msl(void *xtp)
311 struct tcpcb *tp = xtp;
313 struct epoch_tracker et;
314 CURVNET_SET(tp->t_vnet);
318 ostate = tp->t_state;
321 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
323 tcp_free_sackholes(tp);
324 if (callout_pending(&tp->t_timers->tt_2msl) ||
325 !callout_active(&tp->t_timers->tt_2msl)) {
326 INP_WUNLOCK(tp->t_inpcb);
330 callout_deactivate(&tp->t_timers->tt_2msl);
331 if ((inp->inp_flags & INP_DROPPED) != 0) {
336 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
337 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
339 * 2 MSL timeout in shutdown went off. If we're closed but
340 * still waiting for peer to close and connection has been idle
341 * too long delete connection control block. Otherwise, check
344 * If in TIME_WAIT state just ignore as this timeout is handled in
345 * tcp_tw_2msl_scan().
347 * If fastrecycle of FIN_WAIT_2, in FIN_WAIT_2 and receiver has closed,
348 * there's no point in hanging onto FIN_WAIT_2 socket. Just close it.
349 * Ignore fact that there were recent incoming segments.
351 if ((inp->inp_flags & INP_TIMEWAIT) != 0) {
356 if (tcp_fast_finwait2_recycle && tp->t_state == TCPS_FIN_WAIT_2 &&
357 tp->t_inpcb && tp->t_inpcb->inp_socket &&
358 (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE)) {
359 TCPSTAT_INC(tcps_finwait2_drops);
360 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
361 tcp_inpinfo_lock_del(inp, tp);
367 tcp_inpinfo_lock_del(inp, tp);
370 if (ticks - tp->t_rcvtime <= TP_MAXIDLE(tp)) {
371 callout_reset(&tp->t_timers->tt_2msl,
372 TP_KEEPINTVL(tp), tcp_timer_2msl, tp);
374 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
375 tcp_inpinfo_lock_del(inp, tp);
381 tcp_inpinfo_lock_del(inp, tp);
387 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
388 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
391 TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
400 tcp_timer_keep(void *xtp)
402 struct tcpcb *tp = xtp;
403 struct tcptemp *t_template;
405 struct epoch_tracker et;
406 CURVNET_SET(tp->t_vnet);
410 ostate = tp->t_state;
413 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
415 if (callout_pending(&tp->t_timers->tt_keep) ||
416 !callout_active(&tp->t_timers->tt_keep)) {
421 callout_deactivate(&tp->t_timers->tt_keep);
422 if ((inp->inp_flags & INP_DROPPED) != 0) {
427 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
428 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
431 * Because we don't regularly reset the keepalive callout in
432 * the ESTABLISHED state, it may be that we don't actually need
433 * to send a keepalive yet. If that occurs, schedule another
434 * call for the next time the keepalive timer might expire.
436 if (TCPS_HAVEESTABLISHED(tp->t_state)) {
439 idletime = ticks - tp->t_rcvtime;
440 if (idletime < TP_KEEPIDLE(tp)) {
441 callout_reset(&tp->t_timers->tt_keep,
442 TP_KEEPIDLE(tp) - idletime, tcp_timer_keep, tp);
450 * Keep-alive timer went off; send something
451 * or drop connection if idle for too long.
453 TCPSTAT_INC(tcps_keeptimeo);
454 if (tp->t_state < TCPS_ESTABLISHED)
456 if ((V_tcp_always_keepalive ||
457 inp->inp_socket->so_options & SO_KEEPALIVE) &&
458 tp->t_state <= TCPS_CLOSING) {
459 if (ticks - tp->t_rcvtime >= TP_KEEPIDLE(tp) + TP_MAXIDLE(tp))
462 * Send a packet designed to force a response
463 * if the peer is up and reachable:
464 * either an ACK if the connection is still alive,
465 * or an RST if the peer has closed the connection
466 * due to timeout or reboot.
467 * Using sequence number tp->snd_una-1
468 * causes the transmitted zero-length segment
469 * to lie outside the receive window;
470 * by the protocol spec, this requires the
471 * correspondent TCP to respond.
473 TCPSTAT_INC(tcps_keepprobe);
474 t_template = tcpip_maketemplate(inp);
477 tcp_respond(tp, t_template->tt_ipgen,
478 &t_template->tt_t, (struct mbuf *)NULL,
479 tp->rcv_nxt, tp->snd_una - 1, 0);
481 free(t_template, M_TEMP);
483 callout_reset(&tp->t_timers->tt_keep, TP_KEEPINTVL(tp),
486 callout_reset(&tp->t_timers->tt_keep, TP_KEEPIDLE(tp),
490 if (inp->inp_socket->so_options & SO_DEBUG)
491 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
494 TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
500 TCPSTAT_INC(tcps_keepdrops);
501 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
502 tcp_inpinfo_lock_del(inp, tp);
506 tp = tcp_drop(tp, ETIMEDOUT);
509 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
510 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
513 TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
515 tcp_inpinfo_lock_del(inp, tp);
521 tcp_timer_persist(void *xtp)
523 struct tcpcb *tp = xtp;
525 struct epoch_tracker et;
526 CURVNET_SET(tp->t_vnet);
530 ostate = tp->t_state;
533 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
535 if (callout_pending(&tp->t_timers->tt_persist) ||
536 !callout_active(&tp->t_timers->tt_persist)) {
541 callout_deactivate(&tp->t_timers->tt_persist);
542 if ((inp->inp_flags & INP_DROPPED) != 0) {
547 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
548 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
550 * Persistence timer into zero window.
551 * Force a byte to be output, if possible.
553 TCPSTAT_INC(tcps_persisttimeo);
555 * Hack: if the peer is dead/unreachable, we do not
556 * time out if the window is closed. After a full
557 * backoff, drop the connection if the idle time
558 * (no responses to probes) reaches the maximum
559 * backoff that we would use if retransmitting.
561 if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
562 (ticks - tp->t_rcvtime >= tcp_maxpersistidle ||
563 ticks - tp->t_rcvtime >= TCP_REXMTVAL(tp) * tcp_totbackoff)) {
564 TCPSTAT_INC(tcps_persistdrop);
565 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
566 tcp_inpinfo_lock_del(inp, tp);
570 tp = tcp_drop(tp, ETIMEDOUT);
572 tcp_inpinfo_lock_del(inp, tp);
576 * If the user has closed the socket then drop a persisting
577 * connection after a much reduced timeout.
579 if (tp->t_state > TCPS_CLOSE_WAIT &&
580 (ticks - tp->t_rcvtime) >= TCPTV_PERSMAX) {
581 TCPSTAT_INC(tcps_persistdrop);
582 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
583 tcp_inpinfo_lock_del(inp, tp);
587 tp = tcp_drop(tp, ETIMEDOUT);
589 tcp_inpinfo_lock_del(inp, tp);
593 tp->t_flags |= TF_FORCEDATA;
595 (void) tp->t_fb->tfb_tcp_output(tp);
597 tp->t_flags &= ~TF_FORCEDATA;
600 if (tp != NULL && tp->t_inpcb->inp_socket->so_options & SO_DEBUG)
601 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO);
603 TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
610 tcp_timer_rexmt(void * xtp)
612 struct tcpcb *tp = xtp;
613 CURVNET_SET(tp->t_vnet);
616 struct epoch_tracker et;
621 ostate = tp->t_state;
624 KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
626 if (callout_pending(&tp->t_timers->tt_rexmt) ||
627 !callout_active(&tp->t_timers->tt_rexmt)) {
632 callout_deactivate(&tp->t_timers->tt_rexmt);
633 if ((inp->inp_flags & INP_DROPPED) != 0) {
638 KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
639 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
640 tcp_free_sackholes(tp);
641 TCP_LOG_EVENT(tp, NULL, NULL, NULL, TCP_LOG_RTO, 0, 0, NULL, false);
642 if (tp->t_fb->tfb_tcp_rexmit_tmr) {
643 /* The stack has a timer action too. */
644 (*tp->t_fb->tfb_tcp_rexmit_tmr)(tp);
647 * Retransmission timer went off. Message has not
648 * been acked within retransmit interval. Back off
649 * to a longer retransmit interval and retransmit one segment.
651 if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) {
652 tp->t_rxtshift = TCP_MAXRXTSHIFT;
653 TCPSTAT_INC(tcps_timeoutdrop);
654 if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
655 tcp_inpinfo_lock_del(inp, tp);
659 tp = tcp_drop(tp, ETIMEDOUT);
661 tcp_inpinfo_lock_del(inp, tp);
664 if (tp->t_state == TCPS_SYN_SENT) {
666 * If the SYN was retransmitted, indicate CWND to be
667 * limited to 1 segment in cc_conn_init().
670 } else if (tp->t_rxtshift == 1) {
672 * first retransmit; record ssthresh and cwnd so they can
673 * be recovered if this turns out to be a "bad" retransmit.
674 * A retransmit is considered "bad" if an ACK for this
675 * segment is received within RTT/2 interval; the assumption
676 * here is that the ACK was already in flight. See
677 * "On Estimating End-to-End Network Path Properties" by
678 * Allman and Paxson for more details.
680 tp->snd_cwnd_prev = tp->snd_cwnd;
681 tp->snd_ssthresh_prev = tp->snd_ssthresh;
682 tp->snd_recover_prev = tp->snd_recover;
683 if (IN_FASTRECOVERY(tp->t_flags))
684 tp->t_flags |= TF_WASFRECOVERY;
686 tp->t_flags &= ~TF_WASFRECOVERY;
687 if (IN_CONGRECOVERY(tp->t_flags))
688 tp->t_flags |= TF_WASCRECOVERY;
690 tp->t_flags &= ~TF_WASCRECOVERY;
691 if ((tp->t_flags & TF_RCVD_TSTMP) == 0)
692 tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1));
693 /* In the event that we've negotiated timestamps
694 * badrxtwin will be set to the value that we set
695 * the retransmitted packet's to_tsval to by tcp_output
697 tp->t_flags |= TF_PREVVALID;
699 tp->t_flags &= ~TF_PREVVALID;
700 TCPSTAT_INC(tcps_rexmttimeo);
701 if ((tp->t_state == TCPS_SYN_SENT) ||
702 (tp->t_state == TCPS_SYN_RECEIVED))
703 rexmt = tcp_rexmit_initial * tcp_backoff[tp->t_rxtshift];
705 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
706 TCPT_RANGESET(tp->t_rxtcur, rexmt,
707 tp->t_rttmin, TCPTV_REXMTMAX);
710 * We enter the path for PLMTUD if connection is established or, if
711 * connection is FIN_WAIT_1 status, reason for the last is that if
712 * amount of data we send is very small, we could send it in couple of
713 * packets and process straight to FIN. In that case we won't catch
717 isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) ? true : false;
721 if (((V_tcp_pmtud_blackhole_detect == 1) ||
722 (V_tcp_pmtud_blackhole_detect == 2 && !isipv6) ||
723 (V_tcp_pmtud_blackhole_detect == 3 && isipv6)) &&
724 ((tp->t_state == TCPS_ESTABLISHED) ||
725 (tp->t_state == TCPS_FIN_WAIT_1))) {
726 if (tp->t_rxtshift == 1) {
728 * We enter blackhole detection after the first
729 * unsuccessful timer based retransmission.
730 * Then we reduce up to two times the MSS, each
731 * candidate giving two tries of retransmissions.
732 * But we give a candidate only two tries, if it
733 * actually reduces the MSS.
735 tp->t_blackhole_enter = 2;
736 tp->t_blackhole_exit = tp->t_blackhole_enter;
739 if (tp->t_maxseg > V_tcp_v6pmtud_blackhole_mss)
740 tp->t_blackhole_exit += 2;
741 if (tp->t_maxseg > V_tcp_v6mssdflt &&
742 V_tcp_v6pmtud_blackhole_mss > V_tcp_v6mssdflt)
743 tp->t_blackhole_exit += 2;
747 if (tp->t_maxseg > V_tcp_pmtud_blackhole_mss)
748 tp->t_blackhole_exit += 2;
749 if (tp->t_maxseg > V_tcp_mssdflt &&
750 V_tcp_pmtud_blackhole_mss > V_tcp_mssdflt)
751 tp->t_blackhole_exit += 2;
755 if (((tp->t_flags2 & (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) ==
756 (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) &&
757 (tp->t_rxtshift >= tp->t_blackhole_enter &&
758 tp->t_rxtshift < tp->t_blackhole_exit &&
759 (tp->t_rxtshift - tp->t_blackhole_enter) % 2 == 0)) {
761 * Enter Path MTU Black-hole Detection mechanism:
762 * - Disable Path MTU Discovery (IP "DF" bit).
763 * - Reduce MTU to lower value than what we
764 * negotiated with peer.
766 if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) == 0) {
767 /* Record that we may have found a black hole. */
768 tp->t_flags2 |= TF2_PLPMTU_BLACKHOLE;
769 /* Keep track of previous MSS. */
770 tp->t_pmtud_saved_maxseg = tp->t_maxseg;
774 * Reduce the MSS to blackhole value or to the default
775 * in an attempt to retransmit.
779 tp->t_maxseg > V_tcp_v6pmtud_blackhole_mss &&
780 V_tcp_v6pmtud_blackhole_mss > V_tcp_v6mssdflt) {
781 /* Use the sysctl tuneable blackhole MSS. */
782 tp->t_maxseg = V_tcp_v6pmtud_blackhole_mss;
783 TCPSTAT_INC(tcps_pmtud_blackhole_activated);
785 /* Use the default MSS. */
786 tp->t_maxseg = V_tcp_v6mssdflt;
788 * Disable Path MTU Discovery when we switch to
791 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
792 TCPSTAT_INC(tcps_pmtud_blackhole_activated_min_mss);
795 #if defined(INET6) && defined(INET)
799 if (tp->t_maxseg > V_tcp_pmtud_blackhole_mss &&
800 V_tcp_pmtud_blackhole_mss > V_tcp_mssdflt) {
801 /* Use the sysctl tuneable blackhole MSS. */
802 tp->t_maxseg = V_tcp_pmtud_blackhole_mss;
803 TCPSTAT_INC(tcps_pmtud_blackhole_activated);
805 /* Use the default MSS. */
806 tp->t_maxseg = V_tcp_mssdflt;
808 * Disable Path MTU Discovery when we switch to
811 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
812 TCPSTAT_INC(tcps_pmtud_blackhole_activated_min_mss);
816 * Reset the slow-start flight size
817 * as it may depend on the new MSS.
819 if (CC_ALGO(tp)->conn_init != NULL)
820 CC_ALGO(tp)->conn_init(tp->ccv);
823 * If further retransmissions are still unsuccessful
824 * with a lowered MTU, maybe this isn't a blackhole and
825 * we restore the previous MSS and blackhole detection
828 if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) &&
829 (tp->t_rxtshift >= tp->t_blackhole_exit)) {
830 tp->t_flags2 |= TF2_PLPMTU_PMTUD;
831 tp->t_flags2 &= ~TF2_PLPMTU_BLACKHOLE;
832 tp->t_maxseg = tp->t_pmtud_saved_maxseg;
833 TCPSTAT_INC(tcps_pmtud_blackhole_failed);
835 * Reset the slow-start flight size as it
836 * may depend on the new MSS.
838 if (CC_ALGO(tp)->conn_init != NULL)
839 CC_ALGO(tp)->conn_init(tp->ccv);
845 * Disable RFC1323 and SACK if we haven't got any response to
846 * our third SYN to work-around some broken terminal servers
847 * (most of which have hopefully been retired) that have bad VJ
848 * header compression code which trashes TCP segments containing
849 * unknown-to-them TCP options.
851 if (tcp_rexmit_drop_options && (tp->t_state == TCPS_SYN_SENT) &&
852 (tp->t_rxtshift == 3))
853 tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP|TF_SACK_PERMIT);
855 * If we backed off this far, notify the L3 protocol that we're having
856 * connection problems.
858 if (tp->t_rxtshift > TCP_RTT_INVALIDATE) {
860 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0)
861 in6_losing(tp->t_inpcb);
864 in_losing(tp->t_inpcb);
866 tp->snd_nxt = tp->snd_una;
867 tp->snd_recover = tp->snd_max;
869 * Force a segment to be sent.
871 tp->t_flags |= TF_ACKNOW;
873 * If timing a segment in this window, stop the timer.
877 cc_cong_signal(tp, NULL, CC_RTO);
879 (void) tp->t_fb->tfb_tcp_output(tp);
882 if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
883 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
886 TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
893 tcp_timer_activate(struct tcpcb *tp, uint32_t timer_type, u_int delta)
895 struct callout *t_callout;
896 callout_func_t *f_callout;
897 struct inpcb *inp = tp->t_inpcb;
898 int cpu = inp_to_cpuid(inp);
901 if (tp->t_flags & TF_TOE)
905 if (tp->t_timers->tt_flags & TT_STOPPED)
908 switch (timer_type) {
910 t_callout = &tp->t_timers->tt_delack;
911 f_callout = tcp_timer_delack;
914 t_callout = &tp->t_timers->tt_rexmt;
915 f_callout = tcp_timer_rexmt;
918 t_callout = &tp->t_timers->tt_persist;
919 f_callout = tcp_timer_persist;
922 t_callout = &tp->t_timers->tt_keep;
923 f_callout = tcp_timer_keep;
926 t_callout = &tp->t_timers->tt_2msl;
927 f_callout = tcp_timer_2msl;
930 if (tp->t_fb->tfb_tcp_timer_activate) {
931 tp->t_fb->tfb_tcp_timer_activate(tp, timer_type, delta);
934 panic("tp %p bad timer_type %#x", tp, timer_type);
937 callout_stop(t_callout);
939 callout_reset_on(t_callout, delta, f_callout, tp, cpu);
944 tcp_timer_active(struct tcpcb *tp, uint32_t timer_type)
946 struct callout *t_callout;
948 switch (timer_type) {
950 t_callout = &tp->t_timers->tt_delack;
953 t_callout = &tp->t_timers->tt_rexmt;
956 t_callout = &tp->t_timers->tt_persist;
959 t_callout = &tp->t_timers->tt_keep;
962 t_callout = &tp->t_timers->tt_2msl;
965 if (tp->t_fb->tfb_tcp_timer_active) {
966 return(tp->t_fb->tfb_tcp_timer_active(tp, timer_type));
968 panic("tp %p bad timer_type %#x", tp, timer_type);
970 return callout_active(t_callout);
974 * Stop the timer from running, and apply a flag
975 * against the timer_flags that will force the
976 * timer never to run. The flag is needed to assure
977 * a race does not leave it running and cause
978 * the timer to possibly restart itself (keep and persist
979 * especially do this).
982 tcp_timer_suspend(struct tcpcb *tp, uint32_t timer_type)
984 struct callout *t_callout;
987 switch (timer_type) {
989 t_flags = TT_DELACK_SUS;
990 t_callout = &tp->t_timers->tt_delack;
993 t_flags = TT_REXMT_SUS;
994 t_callout = &tp->t_timers->tt_rexmt;
997 t_flags = TT_PERSIST_SUS;
998 t_callout = &tp->t_timers->tt_persist;
1001 t_flags = TT_KEEP_SUS;
1002 t_callout = &tp->t_timers->tt_keep;
1005 t_flags = TT_2MSL_SUS;
1006 t_callout = &tp->t_timers->tt_2msl;
1009 panic("tp:%p bad timer_type 0x%x", tp, timer_type);
1011 tp->t_timers->tt_flags |= t_flags;
1012 return (callout_stop(t_callout));
1016 tcp_timers_unsuspend(struct tcpcb *tp, uint32_t timer_type)
1018 switch (timer_type) {
1020 if (tp->t_timers->tt_flags & TT_DELACK_SUS) {
1021 tp->t_timers->tt_flags &= ~TT_DELACK_SUS;
1022 if (tp->t_flags & TF_DELACK) {
1023 /* Delayed ack timer should be up activate a timer */
1024 tp->t_flags &= ~TF_DELACK;
1025 tcp_timer_activate(tp, TT_DELACK,
1031 if (tp->t_timers->tt_flags & TT_REXMT_SUS) {
1032 tp->t_timers->tt_flags &= ~TT_REXMT_SUS;
1033 if (SEQ_GT(tp->snd_max, tp->snd_una) &&
1034 (tcp_timer_active((tp), TT_PERSIST) == 0) &&
1036 /* We have outstanding data activate a timer */
1037 tcp_timer_activate(tp, TT_REXMT,
1043 if (tp->t_timers->tt_flags & TT_PERSIST_SUS) {
1044 tp->t_timers->tt_flags &= ~TT_PERSIST_SUS;
1045 if (tp->snd_wnd == 0) {
1046 /* Activate the persists timer */
1053 if (tp->t_timers->tt_flags & TT_KEEP_SUS) {
1054 tp->t_timers->tt_flags &= ~TT_KEEP_SUS;
1055 tcp_timer_activate(tp, TT_KEEP,
1056 TCPS_HAVEESTABLISHED(tp->t_state) ?
1057 TP_KEEPIDLE(tp) : TP_KEEPINIT(tp));
1061 if (tp->t_timers->tt_flags &= TT_2MSL_SUS) {
1062 tp->t_timers->tt_flags &= ~TT_2MSL_SUS;
1063 if ((tp->t_state == TCPS_FIN_WAIT_2) &&
1064 ((tp->t_inpcb->inp_socket == NULL) ||
1065 (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE))) {
1066 /* Star the 2MSL timer */
1067 tcp_timer_activate(tp, TT_2MSL,
1068 (tcp_fast_finwait2_recycle) ?
1069 tcp_finwait2_timeout : TP_MAXIDLE(tp));
1074 panic("tp:%p bad timer_type 0x%x", tp, timer_type);
1079 tcp_timer_stop(struct tcpcb *tp, uint32_t timer_type)
1081 struct callout *t_callout;
1083 tp->t_timers->tt_flags |= TT_STOPPED;
1084 switch (timer_type) {
1086 t_callout = &tp->t_timers->tt_delack;
1089 t_callout = &tp->t_timers->tt_rexmt;
1092 t_callout = &tp->t_timers->tt_persist;
1095 t_callout = &tp->t_timers->tt_keep;
1098 t_callout = &tp->t_timers->tt_2msl;
1101 if (tp->t_fb->tfb_tcp_timer_stop) {
1103 * XXXrrs we need to look at this with the
1104 * stop case below (flags).
1106 tp->t_fb->tfb_tcp_timer_stop(tp, timer_type);
1109 panic("tp %p bad timer_type %#x", tp, timer_type);
1112 if (callout_async_drain(t_callout, tcp_timer_discard) == 0) {
1114 * Can't stop the callout, defer tcpcb actual deletion
1115 * to the last one. We do this using the async drain
1116 * function and incrementing the count in
1118 tp->t_timers->tt_draincnt++;