/* $NetBSD: tcp_timer.c,v 1.95.6.1 2021/03/09 15:54:32 martin Exp $ */ /* * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. * 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. * 3. Neither the name of the project 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 PROJECT 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 PROJECT 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. */ /*- * Copyright (c) 1997, 1998, 2001, 2005 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Jason R. Thorpe and Kevin M. Lahey of the Numerical Aerospace Simulation * Facility, NASA Ames Research Center. * This code is derived from software contributed to The NetBSD Foundation * by Charles M. Hannum. * * 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. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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. */ /* * 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. * 3. 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 __KERNEL_RCSID(0, "$NetBSD: tcp_timer.c,v 1.95.6.1 2021/03/09 15:54:32 martin Exp $"); #ifdef _KERNEL_OPT #include "opt_inet.h" #include "opt_tcp_debug.h" #include "opt_net_mpsafe.h" #endif #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef INET6 #include #include #endif #include #include #include #include #include #include #include #ifdef TCP_DEBUG #include #endif /* * Various tunable timer parameters. These are initialized in tcp_init(), * unless they are patched. */ u_int tcp_keepinit = 0; u_int tcp_keepidle = 0; u_int tcp_keepintvl = 0; u_int tcp_keepcnt = 0; /* max idle probes */ int tcp_maxpersistidle = 0; /* max idle time in persist */ static callout_t tcp_slowtimo_ch; #ifdef NET_MPSAFE static struct workqueue *tcp_slowtimo_wq; static struct work tcp_slowtimo_wk; #endif static void tcp_slowtimo_work(struct work *, void *); static void tcp_slowtimo(void *); /* * Time to delay the ACK. This is initialized in tcp_init(), unless * its patched. */ int tcp_delack_ticks = 0; void tcp_timer_rexmt(void *); void tcp_timer_persist(void *); void tcp_timer_keep(void *); void tcp_timer_2msl(void *); const tcp_timer_func_t tcp_timer_funcs[TCPT_NTIMERS] = { tcp_timer_rexmt, tcp_timer_persist, tcp_timer_keep, tcp_timer_2msl, }; /* * Timer state initialization, called from tcp_init(). */ void tcp_timer_init(void) { if (tcp_keepinit == 0) tcp_keepinit = TCPTV_KEEP_INIT; if (tcp_keepidle == 0) tcp_keepidle = TCPTV_KEEP_IDLE; if (tcp_keepintvl == 0) tcp_keepintvl = TCPTV_KEEPINTVL; if (tcp_keepcnt == 0) tcp_keepcnt = TCPTV_KEEPCNT; if (tcp_maxpersistidle == 0) tcp_maxpersistidle = TCPTV_KEEP_IDLE; if (tcp_delack_ticks == 0) tcp_delack_ticks = TCP_DELACK_TICKS; } void tcp_slowtimo_init(void) { #ifdef NET_MPSAFE int error; error = workqueue_create(&tcp_slowtimo_wq, "tcp_slowtimo", tcp_slowtimo_work, NULL, PRI_SOFTNET, IPL_SOFTNET, WQ_MPSAFE); if (error != 0) panic("%s: workqueue_create failed (%d)\n", __func__, error); #endif callout_init(&tcp_slowtimo_ch, CALLOUT_MPSAFE); callout_reset(&tcp_slowtimo_ch, 1, tcp_slowtimo, NULL); } /* * Callout to process delayed ACKs for a TCPCB. */ void tcp_delack(void *arg) { struct tcpcb *tp = arg; /* * If tcp_output() wasn't able to transmit the ACK * for whatever reason, it will restart the delayed * ACK callout. */ mutex_enter(softnet_lock); if ((tp->t_flags & (TF_DEAD | TF_DELACK)) != TF_DELACK) { mutex_exit(softnet_lock); return; } if (!callout_expired(&tp->t_delack_ch)) { mutex_exit(softnet_lock); return; } tp->t_flags |= TF_ACKNOW; KERNEL_LOCK(1, NULL); (void) tcp_output(tp); KERNEL_UNLOCK_ONE(NULL); mutex_exit(softnet_lock); } /* * Tcp protocol timeout routine called every 500 ms. * Updates the timers in all active tcb's and * causes finite state machine actions if timers expire. */ static void tcp_slowtimo_work(struct work *wk, void *arg) { mutex_enter(softnet_lock); tcp_iss_seq += TCP_ISSINCR + (TCP_ISS_RANDOM_MASK & cprng_fast32()); tcp_now++; /* for timestamps */ mutex_exit(softnet_lock); callout_schedule(&tcp_slowtimo_ch, hz / PR_SLOWHZ); } static void tcp_slowtimo(void *arg) { #ifdef NET_MPSAFE workqueue_enqueue(tcp_slowtimo_wq, &tcp_slowtimo_wk, NULL); #else tcp_slowtimo_work(NULL, NULL); #endif } /* * Cancel all timers for TCP tp. */ void tcp_canceltimers(struct tcpcb *tp) { int i; for (i = 0; i < TCPT_NTIMERS; i++) TCP_TIMER_DISARM(tp, i); } const int tcp_backoff[TCP_MAXRXTSHIFT + 1] = { 1, 2, 4, 8, 16, 32, 64, 64, 64, 64, 64, 64, 64 }; const int tcp_totbackoff = 511; /* sum of tcp_backoff[] */ /* * TCP timer processing. */ void tcp_timer_rexmt(void *arg) { struct tcpcb *tp = arg; uint32_t rto; #ifdef TCP_DEBUG struct socket *so = NULL; short ostate; #endif mutex_enter(softnet_lock); if ((tp->t_flags & TF_DEAD) != 0) { mutex_exit(softnet_lock); return; } if (!callout_expired(&tp->t_timer[TCPT_REXMT])) { mutex_exit(softnet_lock); return; } KERNEL_LOCK(1, NULL); if ((tp->t_flags & TF_PMTUD_PEND) && tp->t_inpcb && SEQ_GEQ(tp->t_pmtud_th_seq, tp->snd_una) && SEQ_LT(tp->t_pmtud_th_seq, (int)(tp->snd_una + tp->t_ourmss))) { extern struct sockaddr_in icmpsrc; struct icmp icmp; tp->t_flags &= ~TF_PMTUD_PEND; /* XXX create fake icmp message with relevant entries */ icmp.icmp_nextmtu = tp->t_pmtud_nextmtu; icmp.icmp_ip.ip_len = tp->t_pmtud_ip_len; icmp.icmp_ip.ip_hl = tp->t_pmtud_ip_hl; icmpsrc.sin_addr = tp->t_inpcb->inp_faddr; icmp_mtudisc(&icmp, icmpsrc.sin_addr); /* * Notify all connections to the same peer about * new mss and trigger retransmit. */ in_pcbnotifyall(&tcbtable, icmpsrc.sin_addr, EMSGSIZE, tcp_mtudisc); KERNEL_UNLOCK_ONE(NULL); mutex_exit(softnet_lock); return; } #ifdef TCP_DEBUG if (tp->t_inpcb) so = tp->t_inpcb->inp_socket; #ifdef INET6 if (tp->t_in6pcb) so = tp->t_in6pcb->in6p_socket; #endif ostate = tp->t_state; #endif /* TCP_DEBUG */ /* * Clear the SACK scoreboard, reset FACK estimate. */ tcp_free_sackholes(tp); tp->snd_fack = tp->snd_una; /* * 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; TCP_STATINC(TCP_STAT_TIMEOUTDROP); tp = tcp_drop(tp, tp->t_softerror ? tp->t_softerror : ETIMEDOUT); goto out; } TCP_STATINC(TCP_STAT_REXMTTIMEO); rto = TCP_REXMTVAL(tp); if (rto < tp->t_rttmin) rto = tp->t_rttmin; TCPT_RANGESET(tp->t_rxtcur, rto * tcp_backoff[tp->t_rxtshift], tp->t_rttmin, TCPTV_REXMTMAX); TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); /* * If we are losing and we are trying path MTU discovery, * try turning it off. This will avoid black holes in * the network which suppress or fail to send "packet * too big" ICMP messages. We should ideally do * lots more sophisticated searching to find the right * value here... */ if (tp->t_mtudisc && tp->t_rxtshift > TCP_MAXRXTSHIFT / 6) { TCP_STATINC(TCP_STAT_PMTUBLACKHOLE); /* try turning PMTUD off */ if (tp->t_inpcb) tp->t_mtudisc = 0; #ifdef INET6 /* try using IPv6 minimum MTU */ if (tp->t_in6pcb) tp->t_mtudisc = 0; #endif /* XXX: more sophisticated Black hole recovery code? */ } /* * If losing, let the lower level know and try for * a better route. Also, 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) { if (tp->t_inpcb) in_losing(tp->t_inpcb); #ifdef INET6 if (tp->t_in6pcb) in6_losing(tp->t_in6pcb); #endif /* * This operation is not described in RFC2988. The * point is to keep srtt+4*rttvar constant, so we * should shift right 2 bits to divide by 4, and then * shift right one bit because the storage * representation of rttvar is 1/16s vs 1/32s for * srtt. */ tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT); tp->t_srtt = 0; } tp->snd_nxt = tp->snd_una; tp->snd_high = tp->snd_max; /* * If timing a segment in this window, stop the timer. */ tp->t_rtttime = 0; /* * Remember if we are retransmitting a SYN, because if * we do, set the initial congestion window must be set * to 1 segment. */ if (tp->t_state == TCPS_SYN_SENT) tp->t_flags |= TF_SYN_REXMT; /* * Adjust congestion control parameters. */ tp->t_congctl->slow_retransmit(tp); (void) tcp_output(tp); out: #ifdef TCP_DEBUG if (tp && so->so_options & SO_DEBUG) tcp_trace(TA_USER, ostate, tp, NULL, PRU_SLOWTIMO | (TCPT_REXMT << 8)); #endif KERNEL_UNLOCK_ONE(NULL); mutex_exit(softnet_lock); } void tcp_timer_persist(void *arg) { struct tcpcb *tp = arg; uint32_t rto; #ifdef TCP_DEBUG struct socket *so = NULL; short ostate; #endif mutex_enter(softnet_lock); if ((tp->t_flags & TF_DEAD) != 0) { mutex_exit(softnet_lock); return; } if (!callout_expired(&tp->t_timer[TCPT_PERSIST])) { mutex_exit(softnet_lock); return; } KERNEL_LOCK(1, NULL); #ifdef TCP_DEBUG if (tp->t_inpcb) so = tp->t_inpcb->inp_socket; #ifdef INET6 if (tp->t_in6pcb) so = tp->t_in6pcb->in6p_socket; #endif ostate = tp->t_state; #endif /* TCP_DEBUG */ /* * Persistance timer into zero window. * Force a byte to be output, if possible. */ /* * 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. */ rto = TCP_REXMTVAL(tp); if (rto < tp->t_rttmin) rto = tp->t_rttmin; if (tp->t_rxtshift == TCP_MAXRXTSHIFT && ((tcp_now - tp->t_rcvtime) >= tcp_maxpersistidle || (tcp_now - tp->t_rcvtime) >= rto * tcp_totbackoff)) { TCP_STATINC(TCP_STAT_PERSISTDROPS); tp = tcp_drop(tp, ETIMEDOUT); goto out; } TCP_STATINC(TCP_STAT_PERSISTTIMEO); tcp_setpersist(tp); tp->t_force = 1; (void) tcp_output(tp); tp->t_force = 0; out: #ifdef TCP_DEBUG if (tp && so->so_options & SO_DEBUG) tcp_trace(TA_USER, ostate, tp, NULL, PRU_SLOWTIMO | (TCPT_PERSIST << 8)); #endif KERNEL_UNLOCK_ONE(NULL); mutex_exit(softnet_lock); } void tcp_timer_keep(void *arg) { struct tcpcb *tp = arg; struct socket *so = NULL; /* Quell compiler warning */ #ifdef TCP_DEBUG short ostate; #endif mutex_enter(softnet_lock); if ((tp->t_flags & TF_DEAD) != 0) { mutex_exit(softnet_lock); return; } if (!callout_expired(&tp->t_timer[TCPT_KEEP])) { mutex_exit(softnet_lock); return; } KERNEL_LOCK(1, NULL); #ifdef TCP_DEBUG ostate = tp->t_state; #endif /* TCP_DEBUG */ /* * Keep-alive timer went off; send something * or drop connection if idle for too long. */ TCP_STATINC(TCP_STAT_KEEPTIMEO); if (TCPS_HAVEESTABLISHED(tp->t_state) == 0) goto dropit; if (tp->t_inpcb) so = tp->t_inpcb->inp_socket; #ifdef INET6 if (tp->t_in6pcb) so = tp->t_in6pcb->in6p_socket; #endif KASSERT(so != NULL); if (so->so_options & SO_KEEPALIVE && tp->t_state <= TCPS_CLOSE_WAIT) { if ((tp->t_maxidle > 0) && ((tcp_now - tp->t_rcvtime) >= tp->t_keepidle + tp->t_maxidle)) 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. */ TCP_STATINC(TCP_STAT_KEEPPROBE); (void)tcp_respond(tp, tp->t_template, NULL, NULL, tp->rcv_nxt, tp->snd_una - 1, 0); TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepintvl); } else TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepidle); #ifdef TCP_DEBUG if (tp && so->so_options & SO_DEBUG) tcp_trace(TA_USER, ostate, tp, NULL, PRU_SLOWTIMO | (TCPT_KEEP << 8)); #endif KERNEL_UNLOCK_ONE(NULL); mutex_exit(softnet_lock); return; dropit: TCP_STATINC(TCP_STAT_KEEPDROPS); (void) tcp_drop(tp, ETIMEDOUT); KERNEL_UNLOCK_ONE(NULL); mutex_exit(softnet_lock); } void tcp_timer_2msl(void *arg) { struct tcpcb *tp = arg; #ifdef TCP_DEBUG struct socket *so = NULL; short ostate; #endif mutex_enter(softnet_lock); if ((tp->t_flags & TF_DEAD) != 0) { mutex_exit(softnet_lock); return; } if (!callout_expired(&tp->t_timer[TCPT_2MSL])) { mutex_exit(softnet_lock); return; } /* * 2 MSL timeout went off, clear the SACK scoreboard, reset * the FACK estimate. */ KERNEL_LOCK(1, NULL); tcp_free_sackholes(tp); tp->snd_fack = tp->snd_una; #ifdef TCP_DEBUG if (tp->t_inpcb) so = tp->t_inpcb->inp_socket; #ifdef INET6 if (tp->t_in6pcb) so = tp->t_in6pcb->in6p_socket; #endif ostate = tp->t_state; #endif /* TCP_DEBUG */ /* * 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 (tp->t_state != TCPS_TIME_WAIT && ((tp->t_maxidle == 0) || ((tcp_now - tp->t_rcvtime) <= tp->t_maxidle))) TCP_TIMER_ARM(tp, TCPT_2MSL, tp->t_keepintvl); else tp = tcp_close(tp); #ifdef TCP_DEBUG if (tp && so->so_options & SO_DEBUG) tcp_trace(TA_USER, ostate, tp, NULL, PRU_SLOWTIMO | (TCPT_2MSL << 8)); #endif KERNEL_UNLOCK_ONE(NULL); mutex_exit(softnet_lock); }