515 lines
16 KiB
C
515 lines
16 KiB
C
/* $NetBSD: tcp_timer.c,v 1.46 2000/03/30 13:25:10 augustss Exp $ */
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/*
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* Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
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* 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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* 3. Neither the name of the project 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 PROJECT 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 PROJECT 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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/*-
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* Copyright (c) 1997, 1998 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Jason R. Thorpe and Kevin M. Lahey of the Numerical Aerospace Simulation
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* Facility, NASA Ames Research Center.
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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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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the NetBSD
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* Foundation, Inc. and its contributors.
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* 4. Neither the name of The NetBSD Foundation nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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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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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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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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*/
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#include "opt_inet.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/malloc.h>
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#include <sys/mbuf.h>
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#include <sys/socket.h>
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#include <sys/socketvar.h>
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#include <sys/protosw.h>
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#include <sys/errno.h>
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#include <net/if.h>
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#include <net/route.h>
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#include <netinet/in.h>
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#include <netinet/in_systm.h>
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#include <netinet/ip.h>
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#include <netinet/in_pcb.h>
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#include <netinet/ip_var.h>
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#ifdef INET6
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#ifndef INET
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#include <netinet/in.h>
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#endif
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#include <netinet/ip6.h>
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#include <netinet6/in6_pcb.h>
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#endif
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#include <netinet/tcp.h>
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#include <netinet/tcp_fsm.h>
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#include <netinet/tcp_seq.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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int tcp_keepidle = TCPTV_KEEP_IDLE;
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int tcp_keepintvl = TCPTV_KEEPINTVL;
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int tcp_keepcnt = TCPTV_KEEPCNT; /* max idle probes */
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int tcp_maxpersistidle = TCPTV_KEEP_IDLE; /* max idle time in persist */
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int tcp_maxidle;
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struct tcp_delack_head tcp_delacks;
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/*
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* Fast timeout routine for processing delayed acks
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*/
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void
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tcp_fasttimo()
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{
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struct tcpcb *tp, *ntp;
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int s;
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s = splsoftnet();
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for (tp = tcp_delacks.lh_first; tp != NULL; tp = ntp) {
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/*
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* If tcp_output() can't transmit the ACK for whatever
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* reason, it will remain on the queue for the next
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* time the heartbeat ticks.
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*/
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ntp = tp->t_delack.le_next;
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tp->t_flags |= TF_ACKNOW;
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(void) tcp_output(tp);
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}
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splx(s);
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}
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/*
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* Tcp protocol timeout routine called every 500 ms.
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* Updates the timers in all active tcb's and
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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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struct inpcb *inp, *ninp;
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struct tcpcb *tp;
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#if defined(INET6) && !defined(TCP6)
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struct in6pcb *in6p, *nin6p;
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#endif
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int s;
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long i;
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static int syn_cache_last = 0;
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int skip, mask;
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skip = mask = 0;
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s = splsoftnet();
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tcp_maxidle = tcp_keepcnt * tcp_keepintvl;
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/*
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* Search through tcb's and update active timers.
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*/
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mask |= 1;
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inp = tcbtable.inpt_queue.cqh_first;
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if (inp == (struct inpcb *)0) { /* XXX */
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skip |= 1;
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goto dotcb6;
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}
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for (; inp != (struct inpcb *)&tcbtable.inpt_queue; inp = ninp) {
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ninp = inp->inp_queue.cqe_next;
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tp = intotcpcb(inp);
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if (tp == 0 || tp->t_state == TCPS_LISTEN)
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continue;
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for (i = 0; i < TCPT_NTIMERS; i++) {
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if (TCP_TIMER_ISEXPIRED(tp, i)) {
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TCP_TIMER_DISARM(tp, i);
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(void) tcp_usrreq(tp->t_inpcb->inp_socket,
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PRU_SLOWTIMO, (struct mbuf *)0,
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(struct mbuf *)i, (struct mbuf *)0,
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(struct proc *)0);
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/* XXX NOT MP SAFE */
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if ((ninp == (void *)&tcbtable.inpt_queue &&
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tcbtable.inpt_queue.cqh_last != inp) ||
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ninp->inp_queue.cqe_prev != inp)
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goto tpgone;
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}
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}
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tp->t_idle++;
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if (tp->t_rtt)
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tp->t_rtt++;
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tpgone:
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;
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}
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dotcb6:
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#if defined(INET6) && !defined(TCP6)
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mask |= 2;
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in6p = tcb6.in6p_next;
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if (in6p == (struct in6pcb *)0) { /* XXX */
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skip |= 2;
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goto doiss;
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}
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for (; in6p != (struct in6pcb *)&tcb6; in6p = nin6p) {
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nin6p = in6p->in6p_next;
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tp = in6totcpcb(in6p);
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if (tp == 0 || tp->t_state == TCPS_LISTEN)
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continue;
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for (i = 0; i < TCPT_NTIMERS; i++) {
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if (TCP_TIMER_ISEXPIRED(tp, i)) {
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TCP_TIMER_DISARM(tp, i);
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(void) tcp_usrreq(tp->t_in6pcb->in6p_socket,
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PRU_SLOWTIMO, (struct mbuf *)0,
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(struct mbuf *)i, (struct mbuf *)0,
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(struct proc *)0);
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/* XXX NOT MP SAFE */
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if ((nin6p == (void *)&tcb6 &&
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tcb6.in6p_prev != in6p) ||
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nin6p->in6p_prev != in6p)
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goto tp6gone;
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}
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}
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tp->t_idle++;
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if (tp->t_rtt)
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tp->t_rtt++;
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tp6gone:
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;
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}
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doiss:
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#endif
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if (mask == skip)
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goto done;
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tcp_iss_seq += TCP_ISSINCR; /* increment iss */
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tcp_now++; /* for timestamps */
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if (++syn_cache_last >= tcp_syn_cache_interval) {
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syn_cache_timer();
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syn_cache_last = 0;
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}
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done:
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splx(s);
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}
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/*
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* Cancel all timers for TCP tp.
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*/
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void
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tcp_canceltimers(tp)
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struct tcpcb *tp;
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{
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int i;
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for (i = 0; i < TCPT_NTIMERS; i++)
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TCP_TIMER_DISARM(tp, i);
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}
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int tcp_backoff[TCP_MAXRXTSHIFT + 1] =
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{ 1, 2, 4, 8, 16, 32, 64, 64, 64, 64, 64, 64, 64 };
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int tcp_totbackoff = 511; /* sum of tcp_backoff[] */
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/*
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* TCP timer processing.
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*/
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struct tcpcb *
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tcp_timers(tp, timer)
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struct tcpcb *tp;
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int timer;
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{
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short rto;
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switch (timer) {
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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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case TCPT_2MSL:
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if (tp->t_state != TCPS_TIME_WAIT &&
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((tcp_maxidle == 0) || (tp->t_idle <= tcp_maxidle)))
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TCP_TIMER_ARM(tp, TCPT_2MSL, tcp_keepintvl);
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else
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tp = tcp_close(tp);
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break;
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/*
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* Retransmission timer went off. Message has not
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* been acked within retransmit interval. Back off
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* to a longer retransmit interval and retransmit one segment.
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*/
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case TCPT_REXMT:
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if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) {
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tp->t_rxtshift = TCP_MAXRXTSHIFT;
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tcpstat.tcps_timeoutdrop++;
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tp = tcp_drop(tp, tp->t_softerror ?
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tp->t_softerror : ETIMEDOUT);
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break;
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}
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tcpstat.tcps_rexmttimeo++;
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rto = TCP_REXMTVAL(tp);
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if (rto < tp->t_rttmin)
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rto = tp->t_rttmin;
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TCPT_RANGESET(tp->t_rxtcur, rto * tcp_backoff[tp->t_rxtshift],
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tp->t_rttmin, TCPTV_REXMTMAX);
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TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur);
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#if 0
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/*
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* If we are losing and we are trying path MTU discovery,
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* try turning it off. This will avoid black holes in
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* the network which suppress or fail to send "packet
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* too big" ICMP messages. We should ideally do
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* lots more sophisticated searching to find the right
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* value here...
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*/
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if (ip_mtudisc && tp->t_rxtshift > TCP_MAXRXTSHIFT / 6) {
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struct rtentry *rt = NULL;
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if (tp->t_inpcb)
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rt = in_pcbrtentry(tp->t_inpcb);
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#ifdef INET6
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else if (tp->t_in6pcb)
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rt = in6_pcbrtentry(tp->t_in6pcb);
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#endif
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/* XXX: Black hole recovery code goes here */
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}
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#endif
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/*
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* If losing, let the lower level know and try for
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* a better route. Also, if we backed off this far,
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* our srtt estimate is probably bogus. Clobber it
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* so we'll take the next rtt measurement as our srtt;
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* move the current srtt into rttvar to keep the current
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* retransmit times until then.
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*/
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if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) {
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if (tp->t_inpcb)
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in_losing(tp->t_inpcb);
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#ifdef INET6
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else if (tp->t_in6pcb)
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in6_losing(tp->t_in6pcb);
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#endif
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tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT);
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tp->t_srtt = 0;
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}
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tp->snd_nxt = tp->snd_una;
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/*
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* If timing a segment in this window, stop the timer.
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*/
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tp->t_rtt = 0;
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/*
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* Remember if we are retransmitting a SYN, because if
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* we do, set the initial congestion window must be set
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* to 1 segment.
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*/
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if (tp->t_state == TCPS_SYN_SENT)
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tp->t_flags |= TF_SYN_REXMT;
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/*
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* Close the congestion window down to one segment
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* (we'll open it by one segment for each ack we get).
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* Since we probably have a window's worth of unacked
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* data accumulated, this "slow start" keeps us from
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* dumping all that data as back-to-back packets (which
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* might overwhelm an intermediate gateway).
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*
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* There are two phases to the opening: Initially we
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* open by one mss on each ack. This makes the window
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* size increase exponentially with time. If the
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* window is larger than the path can handle, this
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* exponential growth results in dropped packet(s)
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* almost immediately. To get more time between
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* drops but still "push" the network to take advantage
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* of improving conditions, we switch from exponential
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* to linear window opening at some threshhold size.
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* For a threshhold, we use half the current window
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* size, truncated to a multiple of the mss.
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*
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* (the minimum cwnd that will give us exponential
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* growth is 2 mss. We don't allow the threshhold
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* to go below this.)
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*/
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{
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u_int win = min(tp->snd_wnd, tp->snd_cwnd) / 2 / tp->t_segsz;
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if (win < 2)
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win = 2;
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/* Loss Window MUST be one segment. */
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tp->snd_cwnd = tp->t_segsz;
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tp->snd_ssthresh = win * tp->t_segsz;
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tp->t_dupacks = 0;
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}
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(void) tcp_output(tp);
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break;
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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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case TCPT_PERSIST:
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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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rto = TCP_REXMTVAL(tp);
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if (rto < tp->t_rttmin)
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rto = tp->t_rttmin;
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if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
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(tp->t_idle >= tcp_maxpersistidle ||
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tp->t_idle >= rto * tcp_totbackoff)) {
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tcpstat.tcps_persistdrops++;
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tp = tcp_drop(tp, ETIMEDOUT);
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break;
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}
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tcpstat.tcps_persisttimeo++;
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tcp_setpersist(tp);
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tp->t_force = 1;
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(void) tcp_output(tp);
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tp->t_force = 0;
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break;
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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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case TCPT_KEEP:
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{
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struct socket *so = NULL;
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tcpstat.tcps_keeptimeo++;
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if (TCPS_HAVEESTABLISHED(tp->t_state) == 0)
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goto dropit;
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if (tp->t_inpcb)
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so = tp->t_inpcb->inp_socket;
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#ifdef INET6
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else if (tp->t_in6pcb)
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so = tp->t_in6pcb->in6p_socket;
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#endif
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if (so->so_options & SO_KEEPALIVE &&
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tp->t_state <= TCPS_CLOSE_WAIT) {
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if ((tcp_maxidle > 0) &&
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(tp->t_idle >= 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
|
|
* 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.tcps_keepprobe++;
|
|
if (tcp_compat_42) {
|
|
/*
|
|
* The keepalive packet must have nonzero
|
|
* length to get a 4.2 host to respond.
|
|
*/
|
|
(void)tcp_respond(tp, tp->t_template,
|
|
(struct mbuf *)NULL, NULL, tp->rcv_nxt - 1,
|
|
tp->snd_una - 1, 0);
|
|
} else {
|
|
(void)tcp_respond(tp, tp->t_template,
|
|
(struct mbuf *)NULL, NULL, tp->rcv_nxt,
|
|
tp->snd_una - 1, 0);
|
|
}
|
|
TCP_TIMER_ARM(tp, TCPT_KEEP, tcp_keepintvl);
|
|
} else
|
|
TCP_TIMER_ARM(tp, TCPT_KEEP, tcp_keepidle);
|
|
break;
|
|
}
|
|
dropit:
|
|
tcpstat.tcps_keepdrops++;
|
|
tp = tcp_drop(tp, ETIMEDOUT);
|
|
break;
|
|
}
|
|
return (tp);
|
|
}
|