2d8266af5c
1) Set the persist timer to help time-out connections in the CLOSING state. 2) Honor the keep-alive timer in the CLOSING state. This fixes problems with connections getting "stuck" due to incompletion of the final connection shutdown which can be a BIG problem on busy WWW servers.
362 lines
10 KiB
C
362 lines
10 KiB
C
/*
|
|
* Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995
|
|
* The Regents of the University of California. All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
* 3. All advertising materials mentioning features or use of this software
|
|
* must display the following acknowledgement:
|
|
* This product includes software developed by the University of
|
|
* California, Berkeley and its contributors.
|
|
* 4. Neither the name of the University nor the names of its contributors
|
|
* may be used to endorse or promote products derived from this software
|
|
* without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
* SUCH DAMAGE.
|
|
*
|
|
* @(#)tcp_timer.c 8.2 (Berkeley) 5/24/95
|
|
* $Id: tcp_timer.c,v 1.15 1996/04/04 11:17:04 phk Exp $
|
|
*/
|
|
|
|
#ifndef TUBA_INCLUDE
|
|
#include <sys/param.h>
|
|
#include <sys/queue.h>
|
|
#include <sys/systm.h>
|
|
#include <sys/kernel.h>
|
|
#include <sys/sysctl.h>
|
|
#include <sys/malloc.h>
|
|
#include <sys/mbuf.h>
|
|
#include <sys/socket.h>
|
|
#include <sys/socketvar.h>
|
|
#include <sys/protosw.h>
|
|
#include <sys/errno.h>
|
|
|
|
#include <machine/cpu.h> /* before tcp_seq.h, for tcp_random18() */
|
|
|
|
#include <net/if.h>
|
|
#include <net/route.h>
|
|
|
|
#include <netinet/in.h>
|
|
#include <netinet/in_systm.h>
|
|
#include <netinet/ip.h>
|
|
#include <netinet/in_pcb.h>
|
|
#include <netinet/ip_var.h>
|
|
#include <netinet/tcp.h>
|
|
#include <netinet/tcp_fsm.h>
|
|
#include <netinet/tcp_seq.h>
|
|
#include <netinet/tcp_timer.h>
|
|
#include <netinet/tcp_var.h>
|
|
#include <netinet/tcpip.h>
|
|
|
|
int tcp_keepidle = TCPTV_KEEP_IDLE;
|
|
SYSCTL_INT(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle,
|
|
CTLFLAG_RW, &tcp_keepidle , 0, "");
|
|
|
|
static int tcp_keepintvl = TCPTV_KEEPINTVL;
|
|
SYSCTL_INT(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl,
|
|
CTLFLAG_RW, &tcp_keepintvl , 0, "");
|
|
|
|
static int always_keepalive = 0;
|
|
SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive,
|
|
CTLFLAG_RW, &always_keepalive , 0, "");
|
|
|
|
static int tcp_keepcnt = TCPTV_KEEPCNT;
|
|
/* max idle probes */
|
|
static int tcp_maxpersistidle = TCPTV_KEEP_IDLE;
|
|
/* max idle time in persist */
|
|
int tcp_maxidle;
|
|
#else /* TUBA_INCLUDE */
|
|
|
|
static int tcp_maxpersistidle;
|
|
#endif /* TUBA_INCLUDE */
|
|
|
|
/*
|
|
* Fast timeout routine for processing delayed acks
|
|
*/
|
|
void
|
|
tcp_fasttimo()
|
|
{
|
|
register struct inpcb *inp;
|
|
register struct tcpcb *tp;
|
|
int s;
|
|
|
|
s = splnet();
|
|
|
|
for (inp = tcb.lh_first; inp != NULL; inp = inp->inp_list.le_next) {
|
|
if ((tp = (struct tcpcb *)inp->inp_ppcb) &&
|
|
(tp->t_flags & TF_DELACK)) {
|
|
tp->t_flags &= ~TF_DELACK;
|
|
tp->t_flags |= TF_ACKNOW;
|
|
tcpstat.tcps_delack++;
|
|
(void) tcp_output(tp);
|
|
}
|
|
}
|
|
splx(s);
|
|
}
|
|
|
|
/*
|
|
* Tcp protocol timeout routine called every 500 ms.
|
|
* Updates the timers in all active tcb's and
|
|
* causes finite state machine actions if timers expire.
|
|
*/
|
|
void
|
|
tcp_slowtimo()
|
|
{
|
|
register struct inpcb *ip, *ipnxt;
|
|
register struct tcpcb *tp;
|
|
register int i;
|
|
int s;
|
|
|
|
s = splnet();
|
|
|
|
tcp_maxidle = tcp_keepcnt * tcp_keepintvl;
|
|
|
|
ip = tcb.lh_first;
|
|
if (ip == NULL) {
|
|
splx(s);
|
|
return;
|
|
}
|
|
/*
|
|
* Search through tcb's and update active timers.
|
|
*/
|
|
for (; ip != NULL; ip = ipnxt) {
|
|
ipnxt = ip->inp_list.le_next;
|
|
tp = intotcpcb(ip);
|
|
if (tp == 0 || tp->t_state == TCPS_LISTEN)
|
|
continue;
|
|
for (i = 0; i < TCPT_NTIMERS; i++) {
|
|
if (tp->t_timer[i] && --tp->t_timer[i] == 0) {
|
|
if (tcp_usrreq(tp->t_inpcb->inp_socket,
|
|
PRU_SLOWTIMO, (struct mbuf *)0,
|
|
(struct mbuf *)i, (struct mbuf *)0) == NULL)
|
|
goto tpgone;
|
|
}
|
|
}
|
|
tp->t_idle++;
|
|
tp->t_duration++;
|
|
if (tp->t_rtt)
|
|
tp->t_rtt++;
|
|
tpgone:
|
|
;
|
|
}
|
|
tcp_iss += TCP_ISSINCR/PR_SLOWHZ; /* increment iss */
|
|
#ifdef TCP_COMPAT_42
|
|
if ((int)tcp_iss < 0)
|
|
tcp_iss = TCP_ISSINCR; /* XXX */
|
|
#endif
|
|
tcp_now++; /* for timestamps */
|
|
splx(s);
|
|
}
|
|
#ifndef TUBA_INCLUDE
|
|
|
|
/*
|
|
* Cancel all timers for TCP tp.
|
|
*/
|
|
void
|
|
tcp_canceltimers(tp)
|
|
struct tcpcb *tp;
|
|
{
|
|
register int i;
|
|
|
|
for (i = 0; i < TCPT_NTIMERS; i++)
|
|
tp->t_timer[i] = 0;
|
|
}
|
|
|
|
int tcp_backoff[TCP_MAXRXTSHIFT + 1] =
|
|
{ 1, 2, 4, 8, 16, 32, 64, 64, 64, 64, 64, 64, 64 };
|
|
|
|
static int tcp_totbackoff = 511; /* sum of tcp_backoff[] */
|
|
|
|
/*
|
|
* TCP timer processing.
|
|
*/
|
|
struct tcpcb *
|
|
tcp_timers(tp, timer)
|
|
register struct tcpcb *tp;
|
|
int timer;
|
|
{
|
|
register int rexmt;
|
|
|
|
switch (timer) {
|
|
|
|
/*
|
|
* 2 MSL timeout in shutdown went off. If we're closed but
|
|
* still waiting for peer to close and connection has been idle
|
|
* too long, or if 2MSL time is up from TIME_WAIT, delete connection
|
|
* control block. Otherwise, check again in a bit.
|
|
*/
|
|
case TCPT_2MSL:
|
|
if (tp->t_state != TCPS_TIME_WAIT &&
|
|
tp->t_idle <= tcp_maxidle)
|
|
tp->t_timer[TCPT_2MSL] = tcp_keepintvl;
|
|
else
|
|
tp = tcp_close(tp);
|
|
break;
|
|
|
|
/*
|
|
* Retransmission timer went off. Message has not
|
|
* been acked within retransmit interval. Back off
|
|
* to a longer retransmit interval and retransmit one segment.
|
|
*/
|
|
case TCPT_REXMT:
|
|
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);
|
|
break;
|
|
}
|
|
tcpstat.tcps_rexmttimeo++;
|
|
rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
|
|
TCPT_RANGESET(tp->t_rxtcur, rexmt,
|
|
tp->t_rttmin, TCPTV_REXMTMAX);
|
|
tp->t_timer[TCPT_REXMT] = tp->t_rxtcur;
|
|
/*
|
|
* If losing, let the lower level know and try for
|
|
* a better route. Also, if we backed off this far,
|
|
* our srtt estimate is probably bogus. Clobber it
|
|
* so we'll take the next rtt measurement as our srtt;
|
|
* move the current srtt into rttvar to keep the current
|
|
* retransmit times until then.
|
|
*/
|
|
if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) {
|
|
in_losing(tp->t_inpcb);
|
|
tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT);
|
|
tp->t_srtt = 0;
|
|
}
|
|
tp->snd_nxt = tp->snd_una;
|
|
/*
|
|
* Force a segment to be sent.
|
|
*/
|
|
tp->t_flags |= TF_ACKNOW;
|
|
/*
|
|
* If timing a segment in this window, stop the timer.
|
|
*/
|
|
tp->t_rtt = 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;
|
|
}
|
|
(void) tcp_output(tp);
|
|
break;
|
|
|
|
/*
|
|
* Persistance timer into zero window.
|
|
* Force a byte to be output, if possible.
|
|
*/
|
|
case TCPT_PERSIST:
|
|
tcpstat.tcps_persisttimeo++;
|
|
/*
|
|
* Hack: if the peer is dead/unreachable, we do not
|
|
* time out if the window is closed. After a full
|
|
* backoff, drop the connection if the idle time
|
|
* (no responses to probes) reaches the maximum
|
|
* backoff that we would use if retransmitting.
|
|
*/
|
|
if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
|
|
(tp->t_idle >= tcp_maxpersistidle ||
|
|
tp->t_idle >= TCP_REXMTVAL(tp) * tcp_totbackoff)) {
|
|
tcpstat.tcps_persistdrop++;
|
|
tp = tcp_drop(tp, ETIMEDOUT);
|
|
break;
|
|
}
|
|
tcp_setpersist(tp);
|
|
tp->t_force = 1;
|
|
(void) tcp_output(tp);
|
|
tp->t_force = 0;
|
|
break;
|
|
|
|
/*
|
|
* Keep-alive timer went off; send something
|
|
* or drop connection if idle for too long.
|
|
*/
|
|
case TCPT_KEEP:
|
|
tcpstat.tcps_keeptimeo++;
|
|
if (tp->t_state < TCPS_ESTABLISHED)
|
|
goto dropit;
|
|
if ((always_keepalive ||
|
|
tp->t_inpcb->inp_socket->so_options & SO_KEEPALIVE) &&
|
|
tp->t_state <= TCPS_CLOSING) {
|
|
if (tp->t_idle >= tcp_keepidle + tcp_maxidle)
|
|
goto dropit;
|
|
/*
|
|
* Send a packet designed to force a response
|
|
* if the peer is up and reachable:
|
|
* either an ACK if the connection is still alive,
|
|
* or an RST if the peer has closed the connection
|
|
* due to timeout or reboot.
|
|
* Using sequence number tp->snd_una-1
|
|
* causes the transmitted zero-length segment
|
|
* to lie outside the receive window;
|
|
* by the protocol spec, this requires the
|
|
* correspondent TCP to respond.
|
|
*/
|
|
tcpstat.tcps_keepprobe++;
|
|
#ifdef TCP_COMPAT_42
|
|
/*
|
|
* The keepalive packet must have nonzero length
|
|
* to get a 4.2 host to respond.
|
|
*/
|
|
tcp_respond(tp, tp->t_template, (struct mbuf *)NULL,
|
|
tp->rcv_nxt - 1, tp->snd_una - 1, 0);
|
|
#else
|
|
tcp_respond(tp, tp->t_template, (struct mbuf *)NULL,
|
|
tp->rcv_nxt, tp->snd_una - 1, 0);
|
|
#endif
|
|
tp->t_timer[TCPT_KEEP] = tcp_keepintvl;
|
|
} else
|
|
tp->t_timer[TCPT_KEEP] = tcp_keepidle;
|
|
break;
|
|
dropit:
|
|
tcpstat.tcps_keepdrops++;
|
|
tp = tcp_drop(tp, ETIMEDOUT);
|
|
break;
|
|
}
|
|
return (tp);
|
|
}
|
|
#endif /* TUBA_INCLUDE */
|