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//==========================================================================
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//
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// sys/netinet/tcp_timer.c
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//
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//
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//
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//==========================================================================
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//####BSDCOPYRIGHTBEGIN####
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//
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// -------------------------------------------
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//
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// Portions of this software may have been derived from OpenBSD or other sources,
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// and are covered by the appropriate copyright disclaimers included herein.
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//
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// -------------------------------------------
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//
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//####BSDCOPYRIGHTEND####
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//==========================================================================
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//#####DESCRIPTIONBEGIN####
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//
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// Author(s): gthomas
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// Contributors: gthomas
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// Date: 2000-01-10
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// Purpose:
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// Description:
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//
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//
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//####DESCRIPTIONEND####
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//
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//==========================================================================
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/* $OpenBSD: tcp_timer.c,v 1.15 1999/11/15 05:50:59 hugh Exp $ */
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/* $NetBSD: tcp_timer.c,v 1.14 1996/02/13 23:44:09 christos Exp $ */
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/*
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* Copyright (c) 1982, 1986, 1988, 1990, 1993
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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 8.1 (Berkeley) 6/10/93
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*/
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#ifndef TUBA_INCLUDE
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#include <sys/param.h>
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#ifndef __ECOS
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#include <sys/systm.h>
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#endif
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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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| 83 |
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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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#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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| 97 |
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#ifndef __ECOS
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| 98 |
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#include <dev/rndvar.h>
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| 99 |
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#endif
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| 100 |
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| 101 |
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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_maxpersistidle = TCPTV_KEEP_IDLE; /* max idle time in persist */
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int tcp_maxidle;
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| 105 |
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#endif /* TUBA_INCLUDE */
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/*
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| 107 |
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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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register struct inpcb *inp;
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register struct tcpcb *tp;
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int s;
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s = splsoftnet();
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inp = tcbtable.inpt_queue.cqh_first;
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if (inp) /* XXX */
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for (; inp != (struct inpcb *)&tcbtable.inpt_queue;
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inp = inp->inp_queue.cqe_next) {
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if ((tp = (struct tcpcb *)inp->inp_ppcb) &&
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(tp->t_flags & TF_DELACK)) {
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tp->t_flags &= ~TF_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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}
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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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register struct inpcb *ip, *ipnxt;
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register struct tcpcb *tp;
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int s;
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register long i;
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s = splsoftnet();
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tcp_maxidle = TCPTV_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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ip = tcbtable.inpt_queue.cqh_first;
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if (ip == (struct inpcb *)0) { /* XXX */
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splx(s);
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return;
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}
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for (; ip != (struct inpcb *)&tcbtable.inpt_queue; ip = ipnxt) {
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ipnxt = ip->inp_queue.cqe_next;
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tp = intotcpcb(ip);
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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 (tp->t_timer[i] && --tp->t_timer[i] == 0) {
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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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/* XXX NOT MP SAFE */
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if ((ipnxt == (void *)&tcbtable.inpt_queue &&
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tcbtable.inpt_queue.cqh_last != ip) ||
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ipnxt->inp_queue.cqe_prev != ip)
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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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#ifdef TCP_COMPAT_42
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tcp_iss += TCP_ISSINCR/PR_SLOWHZ; /* increment iss */
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if ((int)tcp_iss < 0)
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tcp_iss = 0; /* XXX */
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#else /* TCP_COMPAT_42 */
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tcp_iss += arc4random() % (2 * TCP_ISSINCR / PR_SLOWHZ) + 1; /* increment iss */
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#endif /* !TCP_COMPAT_42 */
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tcp_now++; /* for timestamps */
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splx(s);
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}
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#ifndef TUBA_INCLUDE
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| 190 |
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/*
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| 191 |
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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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| 197 |
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register int i;
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| 198 |
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| 199 |
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for (i = 0; i < TCPT_NTIMERS; i++)
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tp->t_timer[i] = 0;
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}
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| 202 |
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| 203 |
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int tcp_backoff[TCP_MAXRXTSHIFT + 1] =
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| 204 |
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{ 1, 2, 4, 8, 16, 32, 64, 64, 64, 64, 64, 64, 64 };
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| 206 |
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int tcp_totbackoff = 511; /* sum of tcp_backoff[] */
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| 207 |
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| 208 |
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/*
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| 209 |
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* TCP timer processing.
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| 210 |
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*/
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| 211 |
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struct tcpcb *
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| 212 |
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tcp_timers(tp, timer)
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| 213 |
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register struct tcpcb *tp;
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| 214 |
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int timer;
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| 215 |
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{
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| 216 |
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short rto;
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| 217 |
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#ifdef TCP_SACK
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| 218 |
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struct sackhole *p, *q;
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| 219 |
|
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/*
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| 220 |
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* Free SACK holes for 2MSL and REXMT timers.
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| 221 |
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*/
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| 222 |
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if (timer == TCPT_2MSL || timer == TCPT_REXMT) {
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| 223 |
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q = p = tp->snd_holes;
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| 224 |
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while (p != 0) {
|
| 225 |
|
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q = p->next;
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| 226 |
|
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free(p, M_PCB);
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| 227 |
|
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p = q;
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| 228 |
|
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}
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| 229 |
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tp->snd_holes = 0;
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| 230 |
|
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#if defined(TCP_SACK) && defined(TCP_FACK)
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| 231 |
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tp->snd_fack = tp->snd_una;
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| 232 |
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tp->retran_data = 0;
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| 233 |
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tp->snd_awnd = 0;
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| 234 |
|
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#endif /* TCP_FACK */
|
| 235 |
|
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}
|
| 236 |
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#endif /* TCP_SACK */
|
| 237 |
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|
| 238 |
|
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switch (timer) {
|
| 239 |
|
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|
| 240 |
|
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/*
|
| 241 |
|
|
* 2 MSL timeout in shutdown went off. If we're closed but
|
| 242 |
|
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* still waiting for peer to close and connection has been idle
|
| 243 |
|
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* too long, or if 2MSL time is up from TIME_WAIT, delete connection
|
| 244 |
|
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* control block. Otherwise, check again in a bit.
|
| 245 |
|
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*/
|
| 246 |
|
|
case TCPT_2MSL:
|
| 247 |
|
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if (tp->t_state != TCPS_TIME_WAIT &&
|
| 248 |
|
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tp->t_idle <= tcp_maxidle)
|
| 249 |
|
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tp->t_timer[TCPT_2MSL] = tcp_keepintvl;
|
| 250 |
|
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else
|
| 251 |
|
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tp = tcp_close(tp);
|
| 252 |
|
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break;
|
| 253 |
|
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|
| 254 |
|
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/*
|
| 255 |
|
|
* Retransmission timer went off. Message has not
|
| 256 |
|
|
* been acked within retransmit interval. Back off
|
| 257 |
|
|
* to a longer retransmit interval and retransmit one segment.
|
| 258 |
|
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*/
|
| 259 |
|
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case TCPT_REXMT:
|
| 260 |
|
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if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) {
|
| 261 |
|
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tp->t_rxtshift = TCP_MAXRXTSHIFT;
|
| 262 |
|
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tcpstat.tcps_timeoutdrop++;
|
| 263 |
|
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tp = tcp_drop(tp, tp->t_softerror ?
|
| 264 |
|
|
tp->t_softerror : ETIMEDOUT);
|
| 265 |
|
|
break;
|
| 266 |
|
|
}
|
| 267 |
|
|
tcpstat.tcps_rexmttimeo++;
|
| 268 |
|
|
rto = TCP_REXMTVAL(tp);
|
| 269 |
|
|
if (rto < tp->t_rttmin)
|
| 270 |
|
|
rto = tp->t_rttmin;
|
| 271 |
|
|
TCPT_RANGESET((long) tp->t_rxtcur,
|
| 272 |
|
|
rto * tcp_backoff[tp->t_rxtshift],
|
| 273 |
|
|
tp->t_rttmin, TCPTV_REXMTMAX);
|
| 274 |
|
|
tp->t_timer[TCPT_REXMT] = tp->t_rxtcur;
|
| 275 |
|
|
/*
|
| 276 |
|
|
* If losing, let the lower level know and try for
|
| 277 |
|
|
* a better route. Also, if we backed off this far,
|
| 278 |
|
|
* our srtt estimate is probably bogus. Clobber it
|
| 279 |
|
|
* so we'll take the next rtt measurement as our srtt;
|
| 280 |
|
|
* move the current srtt into rttvar to keep the current
|
| 281 |
|
|
* retransmit times until then.
|
| 282 |
|
|
*/
|
| 283 |
|
|
if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) {
|
| 284 |
|
|
in_losing(tp->t_inpcb);
|
| 285 |
|
|
tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT);
|
| 286 |
|
|
tp->t_srtt = 0;
|
| 287 |
|
|
}
|
| 288 |
|
|
tp->snd_nxt = tp->snd_una;
|
| 289 |
|
|
#if defined(TCP_SACK) || defined(TCP_NEWRENO)
|
| 290 |
|
|
/*
|
| 291 |
|
|
* Note: We overload snd_last to function also as the
|
| 292 |
|
|
* snd_last variable described in RFC 2582
|
| 293 |
|
|
*/
|
| 294 |
|
|
tp->snd_last = tp->snd_max;
|
| 295 |
|
|
#endif /* TCP_SACK or TCP_NEWRENO */
|
| 296 |
|
|
/*
|
| 297 |
|
|
* If timing a segment in this window, stop the timer.
|
| 298 |
|
|
*/
|
| 299 |
|
|
tp->t_rtt = 0;
|
| 300 |
|
|
/*
|
| 301 |
|
|
* Close the congestion window down to one segment
|
| 302 |
|
|
* (we'll open it by one segment for each ack we get).
|
| 303 |
|
|
* Since we probably have a window's worth of unacked
|
| 304 |
|
|
* data accumulated, this "slow start" keeps us from
|
| 305 |
|
|
* dumping all that data as back-to-back packets (which
|
| 306 |
|
|
* might overwhelm an intermediate gateway).
|
| 307 |
|
|
*
|
| 308 |
|
|
* There are two phases to the opening: Initially we
|
| 309 |
|
|
* open by one mss on each ack. This makes the window
|
| 310 |
|
|
* size increase exponentially with time. If the
|
| 311 |
|
|
* window is larger than the path can handle, this
|
| 312 |
|
|
* exponential growth results in dropped packet(s)
|
| 313 |
|
|
* almost immediately. To get more time between
|
| 314 |
|
|
* drops but still "push" the network to take advantage
|
| 315 |
|
|
* of improving conditions, we switch from exponential
|
| 316 |
|
|
* to linear window opening at some threshhold size.
|
| 317 |
|
|
* For a threshhold, we use half the current window
|
| 318 |
|
|
* size, truncated to a multiple of the mss.
|
| 319 |
|
|
*
|
| 320 |
|
|
* (the minimum cwnd that will give us exponential
|
| 321 |
|
|
* growth is 2 mss. We don't allow the threshhold
|
| 322 |
|
|
* to go below this.)
|
| 323 |
|
|
*/
|
| 324 |
|
|
{
|
| 325 |
|
|
u_long win = ulmin(tp->snd_wnd, tp->snd_cwnd) / 2 / tp->t_maxseg;
|
| 326 |
|
|
if (win < 2)
|
| 327 |
|
|
win = 2;
|
| 328 |
|
|
tp->snd_cwnd = tp->t_maxseg;
|
| 329 |
|
|
tp->snd_ssthresh = win * tp->t_maxseg;
|
| 330 |
|
|
tp->t_dupacks = 0;
|
| 331 |
|
|
}
|
| 332 |
|
|
(void) tcp_output(tp);
|
| 333 |
|
|
break;
|
| 334 |
|
|
|
| 335 |
|
|
/*
|
| 336 |
|
|
* Persistance timer into zero window.
|
| 337 |
|
|
* Force a byte to be output, if possible.
|
| 338 |
|
|
*/
|
| 339 |
|
|
case TCPT_PERSIST:
|
| 340 |
|
|
tcpstat.tcps_persisttimeo++;
|
| 341 |
|
|
/*
|
| 342 |
|
|
* Hack: if the peer is dead/unreachable, we do not
|
| 343 |
|
|
* time out if the window is closed. After a full
|
| 344 |
|
|
* backoff, drop the connection if the idle time
|
| 345 |
|
|
* (no responses to probes) reaches the maximum
|
| 346 |
|
|
* backoff that we would use if retransmitting.
|
| 347 |
|
|
*/
|
| 348 |
|
|
rto = TCP_REXMTVAL(tp);
|
| 349 |
|
|
if (rto < tp->t_rttmin)
|
| 350 |
|
|
rto = tp->t_rttmin;
|
| 351 |
|
|
if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
|
| 352 |
|
|
(tp->t_idle >= tcp_maxpersistidle ||
|
| 353 |
|
|
tp->t_idle >= rto * tcp_totbackoff)) {
|
| 354 |
|
|
tcpstat.tcps_persistdrop++;
|
| 355 |
|
|
tp = tcp_drop(tp, ETIMEDOUT);
|
| 356 |
|
|
break;
|
| 357 |
|
|
}
|
| 358 |
|
|
tcp_setpersist(tp);
|
| 359 |
|
|
tp->t_force = 1;
|
| 360 |
|
|
(void) tcp_output(tp);
|
| 361 |
|
|
tp->t_force = 0;
|
| 362 |
|
|
break;
|
| 363 |
|
|
|
| 364 |
|
|
/*
|
| 365 |
|
|
* Keep-alive timer went off; send something
|
| 366 |
|
|
* or drop connection if idle for too long.
|
| 367 |
|
|
*/
|
| 368 |
|
|
case TCPT_KEEP:
|
| 369 |
|
|
tcpstat.tcps_keeptimeo++;
|
| 370 |
|
|
if (TCPS_HAVEESTABLISHED(tp->t_state) == 0)
|
| 371 |
|
|
goto dropit;
|
| 372 |
|
|
if (tp->t_inpcb->inp_socket->so_options & SO_KEEPALIVE &&
|
| 373 |
|
|
tp->t_state <= TCPS_CLOSE_WAIT) {
|
| 374 |
|
|
if (tp->t_idle >= tcp_keepidle + tcp_maxidle)
|
| 375 |
|
|
goto dropit;
|
| 376 |
|
|
/*
|
| 377 |
|
|
* Send a packet designed to force a response
|
| 378 |
|
|
* if the peer is up and reachable:
|
| 379 |
|
|
* either an ACK if the connection is still alive,
|
| 380 |
|
|
* or an RST if the peer has closed the connection
|
| 381 |
|
|
* due to timeout or reboot.
|
| 382 |
|
|
* Using sequence number tp->snd_una-1
|
| 383 |
|
|
* causes the transmitted zero-length segment
|
| 384 |
|
|
* to lie outside the receive window;
|
| 385 |
|
|
* by the protocol spec, this requires the
|
| 386 |
|
|
* correspondent TCP to respond.
|
| 387 |
|
|
*/
|
| 388 |
|
|
tcpstat.tcps_keepprobe++;
|
| 389 |
|
|
#ifdef TCP_COMPAT_42
|
| 390 |
|
|
/*
|
| 391 |
|
|
* The keepalive packet must have nonzero length
|
| 392 |
|
|
* to get a 4.2 host to respond.
|
| 393 |
|
|
*/
|
| 394 |
|
|
tcp_respond(tp,
|
| 395 |
|
|
mtod(tp->t_template, caddr_t),
|
| 396 |
|
|
(struct mbuf *)NULL,
|
| 397 |
|
|
tp->rcv_nxt - 1, tp->snd_una - 1, 0);
|
| 398 |
|
|
#else
|
| 399 |
|
|
tcp_respond(tp,
|
| 400 |
|
|
mtod(tp->t_template, caddr_t),
|
| 401 |
|
|
(struct mbuf *)NULL,
|
| 402 |
|
|
tp->rcv_nxt, tp->snd_una - 1, 0);
|
| 403 |
|
|
#endif
|
| 404 |
|
|
tp->t_timer[TCPT_KEEP] = tcp_keepintvl;
|
| 405 |
|
|
} else
|
| 406 |
|
|
tp->t_timer[TCPT_KEEP] = tcp_keepidle;
|
| 407 |
|
|
break;
|
| 408 |
|
|
dropit:
|
| 409 |
|
|
tcpstat.tcps_keepdrops++;
|
| 410 |
|
|
tp = tcp_drop(tp, ETIMEDOUT);
|
| 411 |
|
|
break;
|
| 412 |
|
|
}
|
| 413 |
|
|
return (tp);
|
| 414 |
|
|
}
|
| 415 |
|
|
#endif /* TUBA_INCLUDE */
|
