* Copyright (c) 1982, 1986 Regents of the University of California.
* All rights reserved. The Berkeley software License Agreement
* specifies the terms and conditions for redistribution.
* @(#)tcp_timer.c 7.3 (Berkeley) %G%
#include "../net/route.h"
* Fast timeout routine for processing delayed acks
register struct inpcb
*inp
;
register struct tcpcb
*tp
;
for (; inp
!= &tcb
; inp
= inp
->inp_next
)
if ((tp
= (struct tcpcb
*)inp
->inp_ppcb
) &&
(tp
->t_flags
& TF_DELACK
)) {
tp
->t_flags
&= ~TF_DELACK
;
tp
->t_flags
|= TF_ACKNOW
;
* 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.
register struct inpcb
*ip
, *ipnxt
;
register struct tcpcb
*tp
;
* Search through tcb's and update active timers.
for (; ip
!= &tcb
; ip
= ipnxt
) {
for (i
= 0; i
< TCPT_NTIMERS
; i
++) {
if (tp
->t_timer
[i
] && --tp
->t_timer
[i
] == 0) {
(void) tcp_usrreq(tp
->t_inpcb
->inp_socket
,
PRU_SLOWTIMO
, (struct mbuf
*)0,
(struct mbuf
*)i
, (struct mbuf
*)0);
if (ipnxt
->inp_prev
!= ip
)
tcp_iss
+= TCP_ISSINCR
/PR_SLOWHZ
; /* increment iss */
* Cancel all timers for TCP tp.
for (i
= 0; i
< TCPT_NTIMERS
; i
++)
int tcp_backoff
[TCP_MAXRXTSHIFT
+1] =
{ 1, 2, 4, 6, 8, 10, 15, 20, 30, 30, 30, 30, 30 };
register struct tcpcb
*tp
;
* 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.
if (tp
->t_state
!= TCPS_TIME_WAIT
&&
tp
->t_idle
<= TCPTV_MAXIDLE
)
tp
->t_timer
[TCPT_2MSL
] = TCPTV_KEEP
;
* 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
) {
tcpstat
.tcps_timeoutdrop
++;
tp
= tcp_drop(tp
, ETIMEDOUT
);
tcpstat
.tcps_rexmttimeo
++;
rexmt
= tcp_beta
* TCPTV_SRTTDFLT
;
rexmt
= (int)(tcp_beta
* tp
->t_srtt
);
rexmt
*= tcp_backoff
[tp
->t_rxtshift
- 1];
TCPT_RANGESET(tp
->t_timer
[TCPT_REXMT
], rexmt
,
* If losing, let the lower level know
* and try for a better route.
if (tp
->t_rxtshift
>= TCP_MAXRXTSHIFT
/ 4 ||
tp
->snd_nxt
= tp
->snd_una
;
* If timing a segment in this window,
* and we have already gotten some timing estimate,
if (tp
->t_rtt
&& tp
->t_srtt
)
* Persistance timer into zero window.
* Force a byte to be output, if possible.
tcpstat
.tcps_persisttimeo
++;
* Keep-alive timer went off; send something
* or drop connection if idle for too long.
tcpstat
.tcps_keeptimeo
++;
if (tp
->t_state
< TCPS_ESTABLISHED
)
if (tp
->t_inpcb
->inp_socket
->so_options
& SO_KEEPALIVE
&&
tp
->t_state
<= TCPS_CLOSE_WAIT
) {
if (tp
->t_idle
>= TCPTV_MAXIDLE
)
* 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
++;
tcp_respond(tp
, tp
->t_template
,
tp
->rcv_nxt
- tcp_keeplen
, tp
->snd_una
- 1, 0);
tp
->t_timer
[TCPT_KEEP
] = TCPTV_KEEP
;
tcpstat
.tcps_keepdrops
++;
tp
= tcp_drop(tp
, ETIMEDOUT
);