/*
* 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.
* 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
* $Id$
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "opt_tcpdebug.h"
#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 <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>
#ifdef TCPDEBUG
#include <netinet/tcp_debug.h>
#endif
int tcp_keepinit = TCPTV_KEEP_INIT;
SYSCTL_INT(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit,
CTLFLAG_RW, &tcp_keepinit , 0, "");
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(void)
{
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(void)
{
register struct inpcb *ip, *ipnxt;
register struct tcpcb *tp;
register int i;
int s;
#ifdef TCPDEBUG
int ostate;
#endif
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) {
#ifdef TCPDEBUG
ostate = tp->t_state;
#endif
tp = tcp_timers(tp, i);
if (tp == NULL)
goto tpgone;
#ifdef TCPDEBUG
if (tp->t_inpcb->inp_socket->so_options
& SO_DEBUG)
tcp_trace(TA_USER, ostate, tp,
(struct tcpiphdr *)0,
PRU_SLOWTIMO);
#endif
}
}
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(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(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) {
u_long maxidle = TCP_REXMTVAL(tp);
if (maxidle < tp->t_rttmin)
maxidle = tp->t_rttmin;
maxidle *= tcp_totbackoff;
if (tp->t_idle >= tcp_maxpersistidle ||
tp->t_idle >= maxidle) {
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 */
