751dea2935
timeouts for TCP and T/TCP connections in the TIME_WAIT state, and we had two separate timed wait queues for them. Now that is has gone, the timeout is always 2*MSL again, and there is no reason to keep two queues (the first was unused anyway!). Also, reimplement the remaining queue using a TAILQ (it was technically impossible before, with two queues).
601 lines
17 KiB
C
601 lines
17 KiB
C
/*-
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* Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)tcp_timer.c 8.2 (Berkeley) 5/24/95
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* $FreeBSD$
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*/
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#include "opt_inet6.h"
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#include "opt_tcpdebug.h"
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#include "opt_tcp_sack.h"
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#include <sys/param.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/mbuf.h>
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#include <sys/mutex.h>
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#include <sys/protosw.h>
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#include <sys/socket.h>
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#include <sys/socketvar.h>
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#include <sys/sysctl.h>
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#include <sys/systm.h>
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#include <net/route.h>
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#include <netinet/in.h>
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#include <netinet/in_pcb.h>
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#include <netinet/in_systm.h>
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#ifdef INET6
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#include <netinet6/in6_pcb.h>
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#endif
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#include <netinet/ip_var.h>
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#include <netinet/tcp.h>
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#include <netinet/tcp_fsm.h>
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#include <netinet/tcp_timer.h>
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#include <netinet/tcp_var.h>
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#include <netinet/tcpip.h>
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#ifdef TCPDEBUG
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#include <netinet/tcp_debug.h>
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#endif
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int tcp_keepinit;
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SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit, CTLTYPE_INT|CTLFLAG_RW,
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&tcp_keepinit, 0, sysctl_msec_to_ticks, "I", "");
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int tcp_keepidle;
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SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle, CTLTYPE_INT|CTLFLAG_RW,
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&tcp_keepidle, 0, sysctl_msec_to_ticks, "I", "");
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int tcp_keepintvl;
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SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl, CTLTYPE_INT|CTLFLAG_RW,
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&tcp_keepintvl, 0, sysctl_msec_to_ticks, "I", "");
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int tcp_delacktime;
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SYSCTL_PROC(_net_inet_tcp, TCPCTL_DELACKTIME, delacktime,
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CTLTYPE_INT|CTLFLAG_RW, &tcp_delacktime, 0, sysctl_msec_to_ticks, "I",
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"Time before a delayed ACK is sent");
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int tcp_msl;
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SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl, CTLTYPE_INT|CTLFLAG_RW,
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&tcp_msl, 0, sysctl_msec_to_ticks, "I", "Maximum segment lifetime");
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int tcp_rexmit_min;
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SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_min, CTLTYPE_INT|CTLFLAG_RW,
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&tcp_rexmit_min, 0, sysctl_msec_to_ticks, "I", "Minimum Retransmission Timeout");
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int tcp_rexmit_slop;
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SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_slop, CTLTYPE_INT|CTLFLAG_RW,
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&tcp_rexmit_slop, 0, sysctl_msec_to_ticks, "I", "Retransmission Timer Slop");
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static int always_keepalive = 1;
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SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive, CTLFLAG_RW,
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&always_keepalive , 0, "Assume SO_KEEPALIVE on all TCP connections");
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static int tcp_keepcnt = TCPTV_KEEPCNT;
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/* max idle probes */
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int tcp_maxpersistidle;
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/* max idle time in persist */
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int tcp_maxidle;
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/*
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* Tcp protocol timeout routine called every 500 ms.
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* Updates timestamps used for TCP
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* causes finite state machine actions if timers expire.
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*/
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void
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tcp_slowtimo()
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{
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tcp_maxidle = tcp_keepcnt * tcp_keepintvl;
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INP_INFO_WLOCK(&tcbinfo);
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(void) tcp_timer_2msl_tw(0);
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INP_INFO_WUNLOCK(&tcbinfo);
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}
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int tcp_syn_backoff[TCP_MAXRXTSHIFT + 1] =
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{ 1, 1, 1, 1, 1, 2, 4, 8, 16, 32, 64, 64, 64 };
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int tcp_backoff[TCP_MAXRXTSHIFT + 1] =
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{ 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 512, 512, 512 };
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static int tcp_totbackoff = 2559; /* sum of tcp_backoff[] */
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static int tcp_timer_race;
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SYSCTL_INT(_net_inet_tcp, OID_AUTO, timer_race, CTLFLAG_RD, &tcp_timer_race,
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0, "Count of t_inpcb races on tcp_discardcb");
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/*
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* TCP timer processing.
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*/
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void
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tcp_timer_delack(xtp)
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void *xtp;
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{
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struct tcpcb *tp = xtp;
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struct inpcb *inp;
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INP_INFO_RLOCK(&tcbinfo);
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inp = tp->t_inpcb;
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/*
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* XXXRW: While this assert is in fact correct, bugs in the tcpcb
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* tear-down mean we need it as a work-around for races between
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* timers and tcp_discardcb().
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*
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* KASSERT(inp != NULL, ("tcp_timer_delack: inp == NULL"));
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*/
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if (inp == NULL) {
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tcp_timer_race++;
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INP_INFO_RUNLOCK(&tcbinfo);
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return;
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}
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INP_LOCK(inp);
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INP_INFO_RUNLOCK(&tcbinfo);
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if ((inp->inp_vflag & INP_DROPPED) || callout_pending(tp->tt_delack)
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|| !callout_active(tp->tt_delack)) {
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INP_UNLOCK(inp);
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return;
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}
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callout_deactivate(tp->tt_delack);
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tp->t_flags |= TF_ACKNOW;
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tcpstat.tcps_delack++;
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(void) tcp_output(tp);
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INP_UNLOCK(inp);
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}
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void
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tcp_timer_2msl(xtp)
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void *xtp;
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{
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struct tcpcb *tp = xtp;
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struct inpcb *inp;
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#ifdef TCPDEBUG
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int ostate;
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ostate = tp->t_state;
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#endif
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/*
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* XXXRW: Does this actually happen?
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*/
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INP_INFO_WLOCK(&tcbinfo);
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inp = tp->t_inpcb;
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/*
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* XXXRW: While this assert is in fact correct, bugs in the tcpcb
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* tear-down mean we need it as a work-around for races between
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* timers and tcp_discardcb().
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*
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* KASSERT(inp != NULL, ("tcp_timer_2msl: inp == NULL"));
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*/
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if (inp == NULL) {
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tcp_timer_race++;
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INP_INFO_WUNLOCK(&tcbinfo);
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return;
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}
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INP_LOCK(inp);
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tcp_free_sackholes(tp);
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if ((inp->inp_vflag & INP_DROPPED) || callout_pending(tp->tt_2msl) ||
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!callout_active(tp->tt_2msl)) {
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INP_UNLOCK(tp->t_inpcb);
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INP_INFO_WUNLOCK(&tcbinfo);
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return;
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}
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callout_deactivate(tp->tt_2msl);
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/*
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* 2 MSL timeout in shutdown went off. If we're closed but
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* still waiting for peer to close and connection has been idle
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* too long, or if 2MSL time is up from TIME_WAIT, delete connection
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* control block. Otherwise, check again in a bit.
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*/
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if (tp->t_state != TCPS_TIME_WAIT &&
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(ticks - tp->t_rcvtime) <= tcp_maxidle)
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callout_reset(tp->tt_2msl, tcp_keepintvl,
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tcp_timer_2msl, tp);
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else
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tp = tcp_close(tp);
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#ifdef TCPDEBUG
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if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
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tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
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PRU_SLOWTIMO);
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#endif
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if (tp != NULL)
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INP_UNLOCK(inp);
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INP_INFO_WUNLOCK(&tcbinfo);
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}
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/*
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* The timed wait queue contains references to each of the TCP sessions
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* currently in the TIME_WAIT state. The queue pointers, including the
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* queue pointers in each tcptw structure, are protected using the global
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* tcbinfo lock, which must be held over queue iteration and modification.
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*/
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static TAILQ_HEAD(, tcptw) twq_2msl;
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void
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tcp_timer_init(void)
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{
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TAILQ_INIT(&twq_2msl);
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}
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void
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tcp_timer_2msl_reset(struct tcptw *tw, int rearm)
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{
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INP_INFO_WLOCK_ASSERT(&tcbinfo);
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INP_LOCK_ASSERT(tw->tw_inpcb);
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if (rearm)
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TAILQ_REMOVE(&twq_2msl, tw, tw_2msl);
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tw->tw_time = ticks + 2 * tcp_msl;
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TAILQ_INSERT_TAIL(&twq_2msl, tw, tw_2msl);
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}
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void
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tcp_timer_2msl_stop(struct tcptw *tw)
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{
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INP_INFO_WLOCK_ASSERT(&tcbinfo);
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TAILQ_REMOVE(&twq_2msl, tw, tw_2msl);
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}
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struct tcptw *
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tcp_timer_2msl_tw(int reuse)
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{
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struct tcptw *tw;
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INP_INFO_WLOCK_ASSERT(&tcbinfo);
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for (;;) {
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tw = TAILQ_FIRST(&twq_2msl);
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if (tw == NULL || (!reuse && tw->tw_time > ticks))
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break;
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INP_LOCK(tw->tw_inpcb);
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tcp_twclose(tw, reuse);
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if (reuse)
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return (tw);
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}
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return (NULL);
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}
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void
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tcp_timer_keep(xtp)
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void *xtp;
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{
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struct tcpcb *tp = xtp;
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struct tcptemp *t_template;
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struct inpcb *inp;
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#ifdef TCPDEBUG
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int ostate;
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ostate = tp->t_state;
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#endif
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INP_INFO_WLOCK(&tcbinfo);
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inp = tp->t_inpcb;
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/*
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* XXXRW: While this assert is in fact correct, bugs in the tcpcb
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* tear-down mean we need it as a work-around for races between
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* timers and tcp_discardcb().
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*
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* KASSERT(inp != NULL, ("tcp_timer_keep: inp == NULL"));
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*/
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if (inp == NULL) {
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tcp_timer_race++;
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INP_INFO_WUNLOCK(&tcbinfo);
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return;
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}
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INP_LOCK(inp);
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if ((inp->inp_vflag & INP_DROPPED) || callout_pending(tp->tt_keep)
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|| !callout_active(tp->tt_keep)) {
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INP_UNLOCK(inp);
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INP_INFO_WUNLOCK(&tcbinfo);
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return;
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}
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callout_deactivate(tp->tt_keep);
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/*
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* Keep-alive timer went off; send something
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* or drop connection if idle for too long.
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*/
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tcpstat.tcps_keeptimeo++;
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if (tp->t_state < TCPS_ESTABLISHED)
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goto dropit;
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if ((always_keepalive || inp->inp_socket->so_options & SO_KEEPALIVE) &&
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tp->t_state <= TCPS_CLOSING) {
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if ((ticks - tp->t_rcvtime) >= tcp_keepidle + tcp_maxidle)
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goto dropit;
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/*
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* Send a packet designed to force a response
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* if the peer is up and reachable:
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* either an ACK if the connection is still alive,
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* or an RST if the peer has closed the connection
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* due to timeout or reboot.
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* Using sequence number tp->snd_una-1
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* causes the transmitted zero-length segment
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* to lie outside the receive window;
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* by the protocol spec, this requires the
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* correspondent TCP to respond.
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*/
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tcpstat.tcps_keepprobe++;
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t_template = tcpip_maketemplate(inp);
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if (t_template) {
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tcp_respond(tp, t_template->tt_ipgen,
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&t_template->tt_t, (struct mbuf *)NULL,
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tp->rcv_nxt, tp->snd_una - 1, 0);
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(void) m_free(dtom(t_template));
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}
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callout_reset(tp->tt_keep, tcp_keepintvl, tcp_timer_keep, tp);
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} else
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callout_reset(tp->tt_keep, tcp_keepidle, tcp_timer_keep, tp);
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#ifdef TCPDEBUG
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if (inp->inp_socket->so_options & SO_DEBUG)
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tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
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PRU_SLOWTIMO);
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#endif
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INP_UNLOCK(inp);
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INP_INFO_WUNLOCK(&tcbinfo);
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return;
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dropit:
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tcpstat.tcps_keepdrops++;
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tp = tcp_drop(tp, ETIMEDOUT);
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#ifdef TCPDEBUG
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if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
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tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
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PRU_SLOWTIMO);
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#endif
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if (tp != NULL)
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INP_UNLOCK(tp->t_inpcb);
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INP_INFO_WUNLOCK(&tcbinfo);
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}
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void
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tcp_timer_persist(xtp)
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void *xtp;
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{
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struct tcpcb *tp = xtp;
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struct inpcb *inp;
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#ifdef TCPDEBUG
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int ostate;
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ostate = tp->t_state;
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#endif
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INP_INFO_WLOCK(&tcbinfo);
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inp = tp->t_inpcb;
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/*
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* XXXRW: While this assert is in fact correct, bugs in the tcpcb
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* tear-down mean we need it as a work-around for races between
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* timers and tcp_discardcb().
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*
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* KASSERT(inp != NULL, ("tcp_timer_persist: inp == NULL"));
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*/
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if (inp == NULL) {
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tcp_timer_race++;
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INP_INFO_WUNLOCK(&tcbinfo);
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return;
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}
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INP_LOCK(inp);
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if ((inp->inp_vflag & INP_DROPPED) || callout_pending(tp->tt_persist)
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|| !callout_active(tp->tt_persist)) {
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INP_UNLOCK(inp);
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INP_INFO_WUNLOCK(&tcbinfo);
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return;
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}
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callout_deactivate(tp->tt_persist);
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/*
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* Persistance timer into zero window.
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* Force a byte to be output, if possible.
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*/
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tcpstat.tcps_persisttimeo++;
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/*
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* Hack: if the peer is dead/unreachable, we do not
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* time out if the window is closed. After a full
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* backoff, drop the connection if the idle time
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* (no responses to probes) reaches the maximum
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* backoff that we would use if retransmitting.
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*/
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if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
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((ticks - tp->t_rcvtime) >= tcp_maxpersistidle ||
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(ticks - tp->t_rcvtime) >= TCP_REXMTVAL(tp) * tcp_totbackoff)) {
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tcpstat.tcps_persistdrop++;
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tp = tcp_drop(tp, ETIMEDOUT);
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goto out;
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}
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tcp_setpersist(tp);
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tp->t_flags |= TF_FORCEDATA;
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(void) tcp_output(tp);
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tp->t_flags &= ~TF_FORCEDATA;
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out:
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#ifdef TCPDEBUG
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if (tp != NULL && tp->t_inpcb->inp_socket->so_options & SO_DEBUG)
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tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO);
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#endif
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if (tp != NULL)
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INP_UNLOCK(inp);
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INP_INFO_WUNLOCK(&tcbinfo);
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}
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void
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tcp_timer_rexmt(xtp)
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void *xtp;
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{
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struct tcpcb *tp = xtp;
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int rexmt;
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int headlocked;
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struct inpcb *inp;
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#ifdef TCPDEBUG
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int ostate;
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ostate = tp->t_state;
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#endif
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INP_INFO_WLOCK(&tcbinfo);
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headlocked = 1;
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inp = tp->t_inpcb;
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/*
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* XXXRW: While this assert is in fact correct, bugs in the tcpcb
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* tear-down mean we need it as a work-around for races between
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* timers and tcp_discardcb().
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*
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* KASSERT(inp != NULL, ("tcp_timer_rexmt: inp == NULL"));
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*/
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if (inp == NULL) {
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tcp_timer_race++;
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INP_INFO_WUNLOCK(&tcbinfo);
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return;
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}
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INP_LOCK(inp);
|
|
if ((inp->inp_vflag & INP_DROPPED) || callout_pending(tp->tt_rexmt)
|
|
|| !callout_active(tp->tt_rexmt)) {
|
|
INP_UNLOCK(inp);
|
|
INP_INFO_WUNLOCK(&tcbinfo);
|
|
return;
|
|
}
|
|
callout_deactivate(tp->tt_rexmt);
|
|
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.tcps_timeoutdrop++;
|
|
tp = tcp_drop(tp, tp->t_softerror ?
|
|
tp->t_softerror : ETIMEDOUT);
|
|
goto out;
|
|
}
|
|
INP_INFO_WUNLOCK(&tcbinfo);
|
|
headlocked = 0;
|
|
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))
|
|
tp->t_flags |= TF_WASFRECOVERY;
|
|
else
|
|
tp->t_flags &= ~TF_WASFRECOVERY;
|
|
tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1));
|
|
}
|
|
tcpstat.tcps_rexmttimeo++;
|
|
if (tp->t_state == TCPS_SYN_SENT)
|
|
rexmt = TCP_REXMTVAL(tp) * 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);
|
|
/*
|
|
* Disable rfc1323 if we havn'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 ((tp->t_state == TCPS_SYN_SENT) && (tp->t_rxtshift == 3))
|
|
tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP);
|
|
/*
|
|
* 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);
|
|
else
|
|
#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;
|
|
/*
|
|
* Close the congestion window down to one segment
|
|
* (we'll open it by one segment for each ack we get).
|
|
* Since we probably have a window's worth of unacked
|
|
* data accumulated, this "slow start" keeps us from
|
|
* dumping all that data as back-to-back packets (which
|
|
* might overwhelm an intermediate gateway).
|
|
*
|
|
* There are two phases to the opening: Initially we
|
|
* open by one mss on each ack. This makes the window
|
|
* size increase exponentially with time. If the
|
|
* window is larger than the path can handle, this
|
|
* exponential growth results in dropped packet(s)
|
|
* almost immediately. To get more time between
|
|
* drops but still "push" the network to take advantage
|
|
* of improving conditions, we switch from exponential
|
|
* to linear window opening at some threshhold size.
|
|
* For a threshhold, we use half the current window
|
|
* size, truncated to a multiple of the mss.
|
|
*
|
|
* (the minimum cwnd that will give us exponential
|
|
* growth is 2 mss. We don't allow the threshhold
|
|
* to go below this.)
|
|
*/
|
|
{
|
|
u_int win = min(tp->snd_wnd, tp->snd_cwnd) / 2 / tp->t_maxseg;
|
|
if (win < 2)
|
|
win = 2;
|
|
tp->snd_cwnd = tp->t_maxseg;
|
|
tp->snd_ssthresh = win * tp->t_maxseg;
|
|
tp->t_dupacks = 0;
|
|
}
|
|
EXIT_FASTRECOVERY(tp);
|
|
(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_UNLOCK(inp);
|
|
if (headlocked)
|
|
INP_INFO_WUNLOCK(&tcbinfo);
|
|
}
|