168 lines
6.7 KiB
C
168 lines
6.7 KiB
C
/* $OpenBSD: tcp_timer.h,v 1.21 2024/01/29 22:47:13 bluhm Exp $ */
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/* $NetBSD: tcp_timer.h,v 1.6 1995/03/26 20:32:37 jtc Exp $ */
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/*
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* Copyright (c) 1982, 1986, 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. 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.h 8.1 (Berkeley) 6/10/93
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*/
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#ifndef _NETINET_TCP_TIMER_H_
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#define _NETINET_TCP_TIMER_H_
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/*
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* Definitions of the TCP timers.
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*/
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#define TCPT_REXMT 0 /* retransmit */
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#define TCPT_PERSIST 1 /* retransmit persistence */
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#define TCPT_KEEP 2 /* keep alive */
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#define TCPT_2MSL 3 /* 2*msl quiet time timer */
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#define TCPT_REAPER 4 /* delayed cleanup timeout */
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#define TCPT_DELACK 5 /* delayed ack timeout */
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#define TCPT_NTIMERS 6
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/*
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* The TCPT_REXMT timer is used to force retransmissions.
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* The TCP has the TCPT_REXMT timer set whenever segments
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* have been sent for which ACKs are expected but not yet
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* received. If an ACK is received which advances tp->snd_una,
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* then the retransmit timer is cleared (if there are no more
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* outstanding segments) or reset to the base value (if there
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* are more ACKs expected). Whenever the retransmit timer goes off,
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* we retransmit one unacknowledged segment, and do a backoff
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* on the retransmit timer.
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*
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* The TCPT_PERSIST timer is used to keep window size information
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* flowing even if the window goes shut. If all previous transmissions
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* have been acknowledged (so that there are no retransmissions in progress),
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* and the window is too small to bother sending anything, then we start
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* the TCPT_PERSIST timer. When it expires, if the window is nonzero,
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* we go to transmit state. Otherwise, at intervals send a single byte
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* into the peer's window to force him to update our window information.
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* We do this at most as often as TCPT_PERSMIN time intervals,
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* but no more frequently than the current estimate of round-trip
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* packet time. The TCPT_PERSIST timer is cleared whenever we receive
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* a window update from the peer.
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*
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* The TCPT_KEEP timer is used to keep connections alive. If an
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* connection is idle (no segments received) for TCPTV_KEEP_INIT amount of time,
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* but not yet established, then we drop the connection. Once the connection
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* is established, if the connection is idle for TCPTV_KEEP_IDLE time
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* (and keepalives have been enabled on the socket), we begin to probe
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* the connection. We force the peer to send us a segment by sending:
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* <SEQ=SND.UNA-1><ACK=RCV.NXT><CTL=ACK>
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* This segment is (deliberately) outside the window, and should elicit
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* an ack segment in response from the peer. If, despite the TCPT_KEEP
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* initiated segments we cannot elicit a response from a peer in TCPT_MAXIDLE
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* amount of time probing, then we drop the connection.
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*/
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/*
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* Time constants.
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*/
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#define TCPTV_MSL TCP_TIME(30) /* max seg lifetime (hah!) */
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#define TCPTV_SRTTBASE 0 /* base roundtrip time;
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if 0, no idea yet */
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#define TCPTV_SRTTDFLT TCP_TIME(3) /* assumed RTT if no info */
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#define TCPTV_PERSMIN TCP_TIME(5) /* retransmit persistence */
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#define TCPTV_PERSMAX TCP_TIME(60) /* maximum persist interval */
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#define TCPTV_KEEP_INIT TCP_TIME(75) /* initial connect keep alive */
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#define TCPTV_KEEP_IDLE TCP_TIME(120*60) /* dflt time before probing */
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#define TCPTV_KEEPINTVL TCP_TIME(75) /* default probe interval */
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#define TCPTV_KEEPCNT 8 /* max probes before drop */
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#define TCPTV_MIN TCP_TIME(1) /* minimum allowable value */
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#define TCPTV_REXMTMAX TCP_TIME(64) /* max allowable REXMT value */
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#define TCP_LINGERTIME 120 /* linger at most 2 minutes */
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#define TCP_MAXRXTSHIFT 12 /* maximum retransmits */
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#define TCP_DELACK_MSECS 200 /* time to delay ACK */
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#ifdef TCPTIMERS
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const char *tcptimers[TCPT_NTIMERS] =
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{ "REXMT", "PERSIST", "KEEP", "2MSL", "REAPER", "DELACK" };
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#endif /* TCPTIMERS */
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/*
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* Init, arm, disarm, and test TCP timers.
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*/
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#define TCP_TIMER_INIT(tp, timer) \
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timeout_set_flags(&(tp)->t_timer[(timer)], \
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tcp_timer_funcs[(timer)], tp, KCLOCK_NONE, \
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TIMEOUT_PROC | TIMEOUT_MPSAFE)
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#define TCP_TIMER_ARM(tp, timer, msecs) \
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do { \
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SET((tp)->t_flags, TF_TIMER << (timer)); \
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timeout_add_msec(&(tp)->t_timer[(timer)], (msecs)); \
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} while (0)
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#define TCP_TIMER_DISARM(tp, timer) \
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do { \
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CLR((tp)->t_flags, TF_TIMER << (timer)); \
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timeout_del(&(tp)->t_timer[(timer)]); \
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} while (0)
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#define TCP_TIMER_ISARMED(tp, timer) \
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ISSET((tp)->t_flags, TF_TIMER << (timer))
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/*
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* Force a time value to be in a certain range.
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*/
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#define TCPT_RANGESET(tv, value, tvmin, tvmax) \
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do { \
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(tv) = (value); \
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if ((tv) < (tvmin)) \
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(tv) = (tvmin); \
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else if ((tv) > (tvmax)) \
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(tv) = (tvmax); \
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} while (/* CONSTCOND */ 0)
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#ifdef _KERNEL
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typedef void (*tcp_timer_func_t)(void *);
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extern const tcp_timer_func_t tcp_timer_funcs[TCPT_NTIMERS];
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extern int tcp_delack_msecs; /* delayed ACK timeout in millisecs */
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extern int tcptv_keep_init;
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extern int tcp_always_keepalive; /* assume SO_KEEPALIVE is always set */
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extern int tcp_keepidle; /* time before keepalive probes begin */
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extern int tcp_keepintvl; /* time between keepalive probes */
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extern int tcp_maxidle; /* time to drop after starting probes */
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extern int tcp_ttl; /* time to live for TCP segs */
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extern int tcp_backoff[];
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void tcp_timer_init(void);
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#endif /* _KERNEL */
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#endif /* _NETINET_TCP_TIMER_H_ */
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