/*- * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)tcp_timer.c 8.2 (Berkeley) 5/24/95 */ #include __FBSDID("$FreeBSD$"); #include "opt_inet.h" #include "opt_inet6.h" #include "opt_tcpdebug.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef INET6 #include #endif #include #include #include #include #ifdef INET6 #include #endif #include #ifdef TCPDEBUG #include #endif int tcp_persmin; SYSCTL_PROC(_net_inet_tcp, OID_AUTO, persmin, CTLTYPE_INT|CTLFLAG_RW, &tcp_persmin, 0, sysctl_msec_to_ticks, "I", "minimum persistence interval"); int tcp_persmax; SYSCTL_PROC(_net_inet_tcp, OID_AUTO, persmax, CTLTYPE_INT|CTLFLAG_RW, &tcp_persmax, 0, sysctl_msec_to_ticks, "I", "maximum persistence interval"); int tcp_keepinit; SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit, CTLTYPE_INT|CTLFLAG_RW, &tcp_keepinit, 0, sysctl_msec_to_ticks, "I", "time to establish connection"); int tcp_keepidle; SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle, CTLTYPE_INT|CTLFLAG_RW, &tcp_keepidle, 0, sysctl_msec_to_ticks, "I", "time before keepalive probes begin"); int tcp_keepintvl; SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl, CTLTYPE_INT|CTLFLAG_RW, &tcp_keepintvl, 0, sysctl_msec_to_ticks, "I", "time between keepalive probes"); int tcp_delacktime; SYSCTL_PROC(_net_inet_tcp, TCPCTL_DELACKTIME, delacktime, CTLTYPE_INT|CTLFLAG_RW, &tcp_delacktime, 0, sysctl_msec_to_ticks, "I", "Time before a delayed ACK is sent"); int tcp_msl; SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl, CTLTYPE_INT|CTLFLAG_RW, &tcp_msl, 0, sysctl_msec_to_ticks, "I", "Maximum segment lifetime"); int tcp_rexmit_min; SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_min, CTLTYPE_INT|CTLFLAG_RW, &tcp_rexmit_min, 0, sysctl_msec_to_ticks, "I", "Minimum Retransmission Timeout"); int tcp_rexmit_slop; SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_slop, CTLTYPE_INT|CTLFLAG_RW, &tcp_rexmit_slop, 0, sysctl_msec_to_ticks, "I", "Retransmission Timer Slop"); static int always_keepalive = 1; SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive, CTLFLAG_RW, &always_keepalive , 0, "Assume SO_KEEPALIVE on all TCP connections"); int tcp_fast_finwait2_recycle = 0; SYSCTL_INT(_net_inet_tcp, OID_AUTO, fast_finwait2_recycle, CTLFLAG_RW, &tcp_fast_finwait2_recycle, 0, "Recycle closed FIN_WAIT_2 connections faster"); int tcp_finwait2_timeout; SYSCTL_PROC(_net_inet_tcp, OID_AUTO, finwait2_timeout, CTLTYPE_INT|CTLFLAG_RW, &tcp_finwait2_timeout, 0, sysctl_msec_to_ticks, "I", "FIN-WAIT2 timeout"); int tcp_keepcnt = TCPTV_KEEPCNT; SYSCTL_INT(_net_inet_tcp, OID_AUTO, keepcnt, CTLFLAG_RW, &tcp_keepcnt, 0, "Number of keepalive probes to send"); /* max idle probes */ int tcp_maxpersistidle; static int tcp_rexmit_drop_options = 0; SYSCTL_INT(_net_inet_tcp, OID_AUTO, rexmit_drop_options, CTLFLAG_RW, &tcp_rexmit_drop_options, 0, "Drop TCP options from 3rd and later retransmitted SYN"); static VNET_DEFINE(int, tcp_pmtud_blackhole_detect); #define V_tcp_pmtud_blackhole_detect VNET(tcp_pmtud_blackhole_detect) SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_detection, CTLFLAG_RW, &VNET_NAME(tcp_pmtud_blackhole_detect), 0, "Path MTU Discovery Black Hole Detection Enabled"); static VNET_DEFINE(int, tcp_pmtud_blackhole_activated); #define V_tcp_pmtud_blackhole_activated \ VNET(tcp_pmtud_blackhole_activated) SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_activated, CTLFLAG_RD, &VNET_NAME(tcp_pmtud_blackhole_activated), 0, "Path MTU Discovery Black Hole Detection, Activation Count"); static VNET_DEFINE(int, tcp_pmtud_blackhole_activated_min_mss); #define V_tcp_pmtud_blackhole_activated_min_mss \ VNET(tcp_pmtud_blackhole_activated_min_mss) SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_activated_min_mss, CTLFLAG_RD, &VNET_NAME(tcp_pmtud_blackhole_activated_min_mss), 0, "Path MTU Discovery Black Hole Detection, Activation Count at min MSS"); static VNET_DEFINE(int, tcp_pmtud_blackhole_failed); #define V_tcp_pmtud_blackhole_failed VNET(tcp_pmtud_blackhole_failed) SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_failed, CTLFLAG_RD, &VNET_NAME(tcp_pmtud_blackhole_failed), 0, "Path MTU Discovery Black Hole Detection, Failure Count"); #ifdef INET static VNET_DEFINE(int, tcp_pmtud_blackhole_mss) = 1200; #define V_tcp_pmtud_blackhole_mss VNET(tcp_pmtud_blackhole_mss) SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_mss, CTLFLAG_RW, &VNET_NAME(tcp_pmtud_blackhole_mss), 0, "Path MTU Discovery Black Hole Detection lowered MSS"); #endif #ifdef INET6 static VNET_DEFINE(int, tcp_v6pmtud_blackhole_mss) = 1220; #define V_tcp_v6pmtud_blackhole_mss VNET(tcp_v6pmtud_blackhole_mss) SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, v6pmtud_blackhole_mss, CTLFLAG_RW, &VNET_NAME(tcp_v6pmtud_blackhole_mss), 0, "Path MTU Discovery IPv6 Black Hole Detection lowered MSS"); #endif static int per_cpu_timers = 0; SYSCTL_INT(_net_inet_tcp, OID_AUTO, per_cpu_timers, CTLFLAG_RW, &per_cpu_timers , 0, "run tcp timers on all cpus"); #define INP_CPU(inp) (per_cpu_timers ? (!CPU_ABSENT(((inp)->inp_flowid % (mp_maxid+1))) ? \ ((inp)->inp_flowid % (mp_maxid+1)) : curcpu) : 0) /* * Tcp protocol timeout routine called every 500 ms. * Updates timestamps used for TCP * causes finite state machine actions if timers expire. */ void tcp_slowtimo(void) { VNET_ITERATOR_DECL(vnet_iter); VNET_LIST_RLOCK_NOSLEEP(); VNET_FOREACH(vnet_iter) { CURVNET_SET(vnet_iter); (void) tcp_tw_2msl_scan(0); CURVNET_RESTORE(); } VNET_LIST_RUNLOCK_NOSLEEP(); } int tcp_syn_backoff[TCP_MAXRXTSHIFT + 1] = { 1, 1, 1, 1, 1, 2, 4, 8, 16, 32, 64, 64, 64 }; int tcp_backoff[TCP_MAXRXTSHIFT + 1] = { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 512, 512, 512 }; static int tcp_totbackoff = 2559; /* sum of tcp_backoff[] */ /* * TCP timer processing. */ void tcp_timer_delack(void *xtp) { struct tcpcb *tp = xtp; struct inpcb *inp; CURVNET_SET(tp->t_vnet); inp = tp->t_inpcb; KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp)); INP_WLOCK(inp); if (callout_pending(&tp->t_timers->tt_delack) || !callout_active(&tp->t_timers->tt_delack)) { INP_WUNLOCK(inp); CURVNET_RESTORE(); return; } callout_deactivate(&tp->t_timers->tt_delack); if ((inp->inp_flags & INP_DROPPED) != 0) { INP_WUNLOCK(inp); CURVNET_RESTORE(); return; } KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0, ("%s: tp %p tcpcb can't be stopped here", __func__, tp)); KASSERT((tp->t_timers->tt_flags & TT_DELACK) != 0, ("%s: tp %p delack callout should be running", __func__, tp)); tp->t_flags |= TF_ACKNOW; TCPSTAT_INC(tcps_delack); (void) tcp_output(tp); INP_WUNLOCK(inp); CURVNET_RESTORE(); } void tcp_timer_2msl(void *xtp) { struct tcpcb *tp = xtp; struct inpcb *inp; CURVNET_SET(tp->t_vnet); #ifdef TCPDEBUG int ostate; ostate = tp->t_state; #endif INP_INFO_WLOCK(&V_tcbinfo); inp = tp->t_inpcb; KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp)); INP_WLOCK(inp); tcp_free_sackholes(tp); if (callout_pending(&tp->t_timers->tt_2msl) || !callout_active(&tp->t_timers->tt_2msl)) { INP_WUNLOCK(tp->t_inpcb); INP_INFO_WUNLOCK(&V_tcbinfo); CURVNET_RESTORE(); return; } callout_deactivate(&tp->t_timers->tt_2msl); if ((inp->inp_flags & INP_DROPPED) != 0) { INP_WUNLOCK(inp); INP_INFO_WUNLOCK(&V_tcbinfo); CURVNET_RESTORE(); return; } KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0, ("%s: tp %p tcpcb can't be stopped here", __func__, tp)); KASSERT((tp->t_timers->tt_flags & TT_2MSL) != 0, ("%s: tp %p 2msl callout should be running", __func__, tp)); /* * 2 MSL timeout in shutdown went off. If we're closed but * still waiting for peer to close and connection has been idle * too long, or if 2MSL time is up from TIME_WAIT, delete connection * control block. Otherwise, check again in a bit. * * If fastrecycle of FIN_WAIT_2, in FIN_WAIT_2 and receiver has closed, * there's no point in hanging onto FIN_WAIT_2 socket. Just close it. * Ignore fact that there were recent incoming segments. */ if (tcp_fast_finwait2_recycle && tp->t_state == TCPS_FIN_WAIT_2 && tp->t_inpcb && tp->t_inpcb->inp_socket && (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE)) { TCPSTAT_INC(tcps_finwait2_drops); tp = tcp_close(tp); } else { if (tp->t_state != TCPS_TIME_WAIT && ticks - tp->t_rcvtime <= TP_MAXIDLE(tp)) { if (!callout_reset(&tp->t_timers->tt_2msl, TP_KEEPINTVL(tp), tcp_timer_2msl, tp)) { tp->t_timers->tt_flags &= ~TT_2MSL_RST; } } else tp = tcp_close(tp); } #ifdef TCPDEBUG if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, PRU_SLOWTIMO); #endif if (tp != NULL) INP_WUNLOCK(inp); INP_INFO_WUNLOCK(&V_tcbinfo); CURVNET_RESTORE(); } void tcp_timer_keep(void *xtp) { struct tcpcb *tp = xtp; struct tcptemp *t_template; struct inpcb *inp; CURVNET_SET(tp->t_vnet); #ifdef TCPDEBUG int ostate; ostate = tp->t_state; #endif INP_INFO_WLOCK(&V_tcbinfo); inp = tp->t_inpcb; KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp)); INP_WLOCK(inp); if (callout_pending(&tp->t_timers->tt_keep) || !callout_active(&tp->t_timers->tt_keep)) { INP_WUNLOCK(inp); INP_INFO_WUNLOCK(&V_tcbinfo); CURVNET_RESTORE(); return; } callout_deactivate(&tp->t_timers->tt_keep); if ((inp->inp_flags & INP_DROPPED) != 0) { INP_WUNLOCK(inp); INP_INFO_WUNLOCK(&V_tcbinfo); CURVNET_RESTORE(); return; } KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0, ("%s: tp %p tcpcb can't be stopped here", __func__, tp)); KASSERT((tp->t_timers->tt_flags & TT_KEEP) != 0, ("%s: tp %p keep callout should be running", __func__, tp)); /* * Keep-alive timer went off; send something * or drop connection if idle for too long. */ TCPSTAT_INC(tcps_keeptimeo); if (tp->t_state < TCPS_ESTABLISHED) goto dropit; if ((always_keepalive || inp->inp_socket->so_options & SO_KEEPALIVE) && tp->t_state <= TCPS_CLOSING) { if (ticks - tp->t_rcvtime >= TP_KEEPIDLE(tp) + TP_MAXIDLE(tp)) goto dropit; /* * Send a packet designed to force a response * if the peer is up and reachable: * either an ACK if the connection is still alive, * or an RST if the peer has closed the connection * due to timeout or reboot. * Using sequence number tp->snd_una-1 * causes the transmitted zero-length segment * to lie outside the receive window; * by the protocol spec, this requires the * correspondent TCP to respond. */ TCPSTAT_INC(tcps_keepprobe); t_template = tcpip_maketemplate(inp); if (t_template) { tcp_respond(tp, t_template->tt_ipgen, &t_template->tt_t, (struct mbuf *)NULL, tp->rcv_nxt, tp->snd_una - 1, 0); free(t_template, M_TEMP); } if (!callout_reset(&tp->t_timers->tt_keep, TP_KEEPINTVL(tp), tcp_timer_keep, tp)) { tp->t_timers->tt_flags &= ~TT_KEEP_RST; } } else if (!callout_reset(&tp->t_timers->tt_keep, TP_KEEPIDLE(tp), tcp_timer_keep, tp)) { tp->t_timers->tt_flags &= ~TT_KEEP_RST; } #ifdef TCPDEBUG if (inp->inp_socket->so_options & SO_DEBUG) tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, PRU_SLOWTIMO); #endif INP_WUNLOCK(inp); INP_INFO_WUNLOCK(&V_tcbinfo); CURVNET_RESTORE(); return; dropit: TCPSTAT_INC(tcps_keepdrops); tp = tcp_drop(tp, ETIMEDOUT); #ifdef TCPDEBUG if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, PRU_SLOWTIMO); #endif if (tp != NULL) INP_WUNLOCK(tp->t_inpcb); INP_INFO_WUNLOCK(&V_tcbinfo); CURVNET_RESTORE(); } void tcp_timer_persist(void *xtp) { struct tcpcb *tp = xtp; struct inpcb *inp; CURVNET_SET(tp->t_vnet); #ifdef TCPDEBUG int ostate; ostate = tp->t_state; #endif INP_INFO_WLOCK(&V_tcbinfo); inp = tp->t_inpcb; KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp)); INP_WLOCK(inp); if (callout_pending(&tp->t_timers->tt_persist) || !callout_active(&tp->t_timers->tt_persist)) { INP_WUNLOCK(inp); INP_INFO_WUNLOCK(&V_tcbinfo); CURVNET_RESTORE(); return; } callout_deactivate(&tp->t_timers->tt_persist); if ((inp->inp_flags & INP_DROPPED) != 0) { INP_WUNLOCK(inp); INP_INFO_WUNLOCK(&V_tcbinfo); CURVNET_RESTORE(); return; } KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0, ("%s: tp %p tcpcb can't be stopped here", __func__, tp)); KASSERT((tp->t_timers->tt_flags & TT_PERSIST) != 0, ("%s: tp %p persist callout should be running", __func__, tp)); /* * Persistance timer into zero window. * Force a byte to be output, if possible. */ TCPSTAT_INC(tcps_persisttimeo); /* * Hack: if the peer is dead/unreachable, we do not * time out if the window is closed. After a full * backoff, drop the connection if the idle time * (no responses to probes) reaches the maximum * backoff that we would use if retransmitting. */ if (tp->t_rxtshift == TCP_MAXRXTSHIFT && (ticks - tp->t_rcvtime >= tcp_maxpersistidle || ticks - tp->t_rcvtime >= TCP_REXMTVAL(tp) * tcp_totbackoff)) { TCPSTAT_INC(tcps_persistdrop); tp = tcp_drop(tp, ETIMEDOUT); goto out; } /* * If the user has closed the socket then drop a persisting * connection after a much reduced timeout. */ if (tp->t_state > TCPS_CLOSE_WAIT && (ticks - tp->t_rcvtime) >= TCPTV_PERSMAX) { TCPSTAT_INC(tcps_persistdrop); tp = tcp_drop(tp, ETIMEDOUT); goto out; } tcp_setpersist(tp); tp->t_flags |= TF_FORCEDATA; (void) tcp_output(tp); tp->t_flags &= ~TF_FORCEDATA; out: #ifdef TCPDEBUG if (tp != NULL && tp->t_inpcb->inp_socket->so_options & SO_DEBUG) tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO); #endif if (tp != NULL) INP_WUNLOCK(inp); INP_INFO_WUNLOCK(&V_tcbinfo); CURVNET_RESTORE(); } void tcp_timer_rexmt(void * xtp) { struct tcpcb *tp = xtp; CURVNET_SET(tp->t_vnet); int rexmt; int headlocked; struct inpcb *inp; #ifdef TCPDEBUG int ostate; ostate = tp->t_state; #endif INP_INFO_RLOCK(&V_tcbinfo); inp = tp->t_inpcb; KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp)); INP_WLOCK(inp); if (callout_pending(&tp->t_timers->tt_rexmt) || !callout_active(&tp->t_timers->tt_rexmt)) { INP_WUNLOCK(inp); INP_INFO_RUNLOCK(&V_tcbinfo); CURVNET_RESTORE(); return; } callout_deactivate(&tp->t_timers->tt_rexmt); if ((inp->inp_flags & INP_DROPPED) != 0) { INP_WUNLOCK(inp); INP_INFO_RUNLOCK(&V_tcbinfo); CURVNET_RESTORE(); return; } KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0, ("%s: tp %p tcpcb can't be stopped here", __func__, tp)); KASSERT((tp->t_timers->tt_flags & TT_REXMT) != 0, ("%s: tp %p rexmt callout should be running", __func__, tp)); tcp_free_sackholes(tp); /* * Retransmission timer went off. Message has not * been acked within retransmit interval. Back off * to a longer retransmit interval and retransmit one segment. */ if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) { tp->t_rxtshift = TCP_MAXRXTSHIFT; TCPSTAT_INC(tcps_timeoutdrop); in_pcbref(inp); INP_INFO_RUNLOCK(&V_tcbinfo); INP_WUNLOCK(inp); INP_INFO_WLOCK(&V_tcbinfo); INP_WLOCK(inp); if (in_pcbrele_wlocked(inp)) { INP_INFO_WUNLOCK(&V_tcbinfo); CURVNET_RESTORE(); return; } if (inp->inp_flags & INP_DROPPED) { INP_WUNLOCK(inp); INP_INFO_WUNLOCK(&V_tcbinfo); CURVNET_RESTORE(); return; } tp = tcp_drop(tp, tp->t_softerror ? tp->t_softerror : ETIMEDOUT); headlocked = 1; goto out; } INP_INFO_RUNLOCK(&V_tcbinfo); headlocked = 0; if (tp->t_state == TCPS_SYN_SENT) { /* * If the SYN was retransmitted, indicate CWND to be * limited to 1 segment in cc_conn_init(). */ tp->snd_cwnd = 1; } else if (tp->t_rxtshift == 1) { /* * first retransmit; record ssthresh and cwnd so they can * be recovered if this turns out to be a "bad" retransmit. * A retransmit is considered "bad" if an ACK for this * segment is received within RTT/2 interval; the assumption * here is that the ACK was already in flight. See * "On Estimating End-to-End Network Path Properties" by * Allman and Paxson for more details. */ tp->snd_cwnd_prev = tp->snd_cwnd; tp->snd_ssthresh_prev = tp->snd_ssthresh; tp->snd_recover_prev = tp->snd_recover; if (IN_FASTRECOVERY(tp->t_flags)) tp->t_flags |= TF_WASFRECOVERY; else tp->t_flags &= ~TF_WASFRECOVERY; if (IN_CONGRECOVERY(tp->t_flags)) tp->t_flags |= TF_WASCRECOVERY; else tp->t_flags &= ~TF_WASCRECOVERY; tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1)); tp->t_flags |= TF_PREVVALID; } else tp->t_flags &= ~TF_PREVVALID; TCPSTAT_INC(tcps_rexmttimeo); if ((tp->t_state == TCPS_SYN_SENT) || (tp->t_state == TCPS_SYN_RECEIVED)) rexmt = TCPTV_RTOBASE * tcp_syn_backoff[tp->t_rxtshift]; else rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift]; TCPT_RANGESET(tp->t_rxtcur, rexmt, tp->t_rttmin, TCPTV_REXMTMAX); /* * We enter the path for PLMTUD if connection is established or, if * connection is FIN_WAIT_1 status, reason for the last is that if * amount of data we send is very small, we could send it in couple of * packets and process straight to FIN. In that case we won't catch * ESTABLISHED state. */ if (V_tcp_pmtud_blackhole_detect && (((tp->t_state == TCPS_ESTABLISHED)) || (tp->t_state == TCPS_FIN_WAIT_1))) { int optlen; #ifdef INET6 int isipv6; #endif /* * Idea here is that at each stage of mtu probe (usually, 1448 * -> 1188 -> 524) should be given 2 chances to recover before * further clamping down. 'tp->t_rxtshift % 2 == 0' should * take care of that. */ if (((tp->t_flags2 & (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) == (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) && (tp->t_rxtshift >= 2 && tp->t_rxtshift % 2 == 0)) { /* * Enter Path MTU Black-hole Detection mechanism: * - Disable Path MTU Discovery (IP "DF" bit). * - Reduce MTU to lower value than what we * negotiated with peer. */ /* Record that we may have found a black hole. */ tp->t_flags2 |= TF2_PLPMTU_BLACKHOLE; /* Keep track of previous MSS. */ optlen = tp->t_maxopd - tp->t_maxseg; tp->t_pmtud_saved_maxopd = tp->t_maxopd; /* * Reduce the MSS to blackhole value or to the default * in an attempt to retransmit. */ #ifdef INET6 isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) ? 1 : 0; if (isipv6 && tp->t_maxopd > V_tcp_v6pmtud_blackhole_mss) { /* Use the sysctl tuneable blackhole MSS. */ tp->t_maxopd = V_tcp_v6pmtud_blackhole_mss; V_tcp_pmtud_blackhole_activated++; } else if (isipv6) { /* Use the default MSS. */ tp->t_maxopd = V_tcp_v6mssdflt; /* * Disable Path MTU Discovery when we switch to * minmss. */ tp->t_flags2 &= ~TF2_PLPMTU_PMTUD; V_tcp_pmtud_blackhole_activated_min_mss++; } #endif #if defined(INET6) && defined(INET) else #endif #ifdef INET if (tp->t_maxopd > V_tcp_pmtud_blackhole_mss) { /* Use the sysctl tuneable blackhole MSS. */ tp->t_maxopd = V_tcp_pmtud_blackhole_mss; V_tcp_pmtud_blackhole_activated++; } else { /* Use the default MSS. */ tp->t_maxopd = V_tcp_mssdflt; /* * Disable Path MTU Discovery when we switch to * minmss. */ tp->t_flags2 &= ~TF2_PLPMTU_PMTUD; V_tcp_pmtud_blackhole_activated_min_mss++; } #endif tp->t_maxseg = tp->t_maxopd - optlen; /* * Reset the slow-start flight size * as it may depend on the new MSS. */ if (CC_ALGO(tp)->conn_init != NULL) CC_ALGO(tp)->conn_init(tp->ccv); } else { /* * If further retransmissions are still unsuccessful * with a lowered MTU, maybe this isn't a blackhole and * we restore the previous MSS and blackhole detection * flags. * The limit '6' is determined by giving each probe * stage (1448, 1188, 524) 2 chances to recover. */ if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) && (tp->t_rxtshift > 6)) { tp->t_flags2 |= TF2_PLPMTU_PMTUD; tp->t_flags2 &= ~TF2_PLPMTU_BLACKHOLE; optlen = tp->t_maxopd - tp->t_maxseg; tp->t_maxopd = tp->t_pmtud_saved_maxopd; tp->t_maxseg = tp->t_maxopd - optlen; V_tcp_pmtud_blackhole_failed++; /* * Reset the slow-start flight size as it * may depend on the new MSS. */ if (CC_ALGO(tp)->conn_init != NULL) CC_ALGO(tp)->conn_init(tp->ccv); } } } /* * Disable RFC1323 and SACK if we haven't got any response to * our third SYN to work-around some broken terminal servers * (most of which have hopefully been retired) that have bad VJ * header compression code which trashes TCP segments containing * unknown-to-them TCP options. */ if (tcp_rexmit_drop_options && (tp->t_state == TCPS_SYN_SENT) && (tp->t_rxtshift == 3)) tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP|TF_SACK_PERMIT); /* * If we backed off this far, our srtt estimate is probably bogus. * Clobber it so we'll take the next rtt measurement as our srtt; * move the current srtt into rttvar to keep the current * retransmit times until then. */ if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) { #ifdef INET6 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) in6_losing(tp->t_inpcb); #endif tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT); tp->t_srtt = 0; } tp->snd_nxt = tp->snd_una; tp->snd_recover = tp->snd_max; /* * Force a segment to be sent. */ tp->t_flags |= TF_ACKNOW; /* * If timing a segment in this window, stop the timer. */ tp->t_rtttime = 0; cc_cong_signal(tp, NULL, CC_RTO); (void) tcp_output(tp); out: #ifdef TCPDEBUG if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0, PRU_SLOWTIMO); #endif if (tp != NULL) INP_WUNLOCK(inp); if (headlocked) INP_INFO_WUNLOCK(&V_tcbinfo); CURVNET_RESTORE(); } void tcp_timer_activate(struct tcpcb *tp, uint32_t timer_type, u_int delta) { struct callout *t_callout; timeout_t *f_callout; struct inpcb *inp = tp->t_inpcb; int cpu = INP_CPU(inp); uint32_t f_reset; #ifdef TCP_OFFLOAD if (tp->t_flags & TF_TOE) return; #endif if (tp->t_timers->tt_flags & TT_STOPPED) return; switch (timer_type) { case TT_DELACK: t_callout = &tp->t_timers->tt_delack; f_callout = tcp_timer_delack; f_reset = TT_DELACK_RST; break; case TT_REXMT: t_callout = &tp->t_timers->tt_rexmt; f_callout = tcp_timer_rexmt; f_reset = TT_REXMT_RST; break; case TT_PERSIST: t_callout = &tp->t_timers->tt_persist; f_callout = tcp_timer_persist; f_reset = TT_PERSIST_RST; break; case TT_KEEP: t_callout = &tp->t_timers->tt_keep; f_callout = tcp_timer_keep; f_reset = TT_KEEP_RST; break; case TT_2MSL: t_callout = &tp->t_timers->tt_2msl; f_callout = tcp_timer_2msl; f_reset = TT_2MSL_RST; break; default: panic("tp %p bad timer_type %#x", tp, timer_type); } if (delta == 0) { if ((tp->t_timers->tt_flags & timer_type) && callout_stop(t_callout) && (tp->t_timers->tt_flags & f_reset)) { tp->t_timers->tt_flags &= ~(timer_type | f_reset); } } else { if ((tp->t_timers->tt_flags & timer_type) == 0) { tp->t_timers->tt_flags |= (timer_type | f_reset); callout_reset_on(t_callout, delta, f_callout, tp, cpu); } else { /* Reset already running callout on the same CPU. */ if (!callout_reset(t_callout, delta, f_callout, tp)) { /* * Callout not cancelled, consider it as not * properly restarted. */ tp->t_timers->tt_flags &= ~f_reset; } } } } int tcp_timer_active(struct tcpcb *tp, uint32_t timer_type) { struct callout *t_callout; switch (timer_type) { case TT_DELACK: t_callout = &tp->t_timers->tt_delack; break; case TT_REXMT: t_callout = &tp->t_timers->tt_rexmt; break; case TT_PERSIST: t_callout = &tp->t_timers->tt_persist; break; case TT_KEEP: t_callout = &tp->t_timers->tt_keep; break; case TT_2MSL: t_callout = &tp->t_timers->tt_2msl; break; default: panic("tp %p bad timer_type %#x", tp, timer_type); } return callout_active(t_callout); } void tcp_timer_stop(struct tcpcb *tp, uint32_t timer_type) { struct callout *t_callout; timeout_t *f_callout; uint32_t f_reset; tp->t_timers->tt_flags |= TT_STOPPED; switch (timer_type) { case TT_DELACK: t_callout = &tp->t_timers->tt_delack; f_callout = tcp_timer_delack_discard; f_reset = TT_DELACK_RST; break; case TT_REXMT: t_callout = &tp->t_timers->tt_rexmt; f_callout = tcp_timer_rexmt_discard; f_reset = TT_REXMT_RST; break; case TT_PERSIST: t_callout = &tp->t_timers->tt_persist; f_callout = tcp_timer_persist_discard; f_reset = TT_PERSIST_RST; break; case TT_KEEP: t_callout = &tp->t_timers->tt_keep; f_callout = tcp_timer_keep_discard; f_reset = TT_KEEP_RST; break; case TT_2MSL: t_callout = &tp->t_timers->tt_2msl; f_callout = tcp_timer_2msl_discard; f_reset = TT_2MSL_RST; break; default: panic("tp %p bad timer_type %#x", tp, timer_type); } if (tp->t_timers->tt_flags & timer_type) { if (callout_stop(t_callout) && (tp->t_timers->tt_flags & f_reset)) { tp->t_timers->tt_flags &= ~(timer_type | f_reset); } else { /* * Can't stop the callout, defer tcpcb actual deletion * to the last tcp timer discard callout. * The TT_STOPPED flag will ensure that no tcp timer * callouts can be restarted on our behalf, and * past this point currently running callouts waiting * on inp lock will return right away after the * classical check for callout reset/stop events: * callout_pending() || !callout_active() */ callout_reset(t_callout, 1, f_callout, tp); } } } #define ticks_to_msecs(t) (1000*(t) / hz) void tcp_timer_to_xtimer(struct tcpcb *tp, struct tcp_timer *timer, struct xtcp_timer *xtimer) { sbintime_t now; bzero(xtimer, sizeof(*xtimer)); if (timer == NULL) return; now = getsbinuptime(); if (callout_active(&timer->tt_delack)) xtimer->tt_delack = (timer->tt_delack.c_time - now) / SBT_1MS; if (callout_active(&timer->tt_rexmt)) xtimer->tt_rexmt = (timer->tt_rexmt.c_time - now) / SBT_1MS; if (callout_active(&timer->tt_persist)) xtimer->tt_persist = (timer->tt_persist.c_time - now) / SBT_1MS; if (callout_active(&timer->tt_keep)) xtimer->tt_keep = (timer->tt_keep.c_time - now) / SBT_1MS; if (callout_active(&timer->tt_2msl)) xtimer->tt_2msl = (timer->tt_2msl.c_time - now) / SBT_1MS; xtimer->t_rcvtime = ticks_to_msecs(ticks - tp->t_rcvtime); }