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- /* $OpenBSD: tcp_timer.h,v 1.13 2011/07/06 23:44:20 sthen Exp $ */
- /* $NetBSD: tcp_timer.h,v 1.6 1995/03/26 20:32:37 jtc Exp $ */
- /*
- * Copyright (c) 1982, 1986, 1993
- * 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. 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.h 8.1 (Berkeley) 6/10/93
- */
- #ifndef _NETINET_TCP_TIMER_H_
- #define _NETINET_TCP_TIMER_H_
- /*
- * Definitions of the TCP timers. These timers are counted
- * down PR_SLOWHZ times a second.
- */
- #define TCPT_NTIMERS 4
- #define TCPT_REXMT 0 /* retransmit */
- #define TCPT_PERSIST 1 /* retransmit persistence */
- #define TCPT_KEEP 2 /* keep alive */
- #define TCPT_2MSL 3 /* 2*msl quiet time timer */
- /*
- * The TCPT_REXMT timer is used to force retransmissions.
- * The TCP has the TCPT_REXMT timer set whenever segments
- * have been sent for which ACKs are expected but not yet
- * received. If an ACK is received which advances tp->snd_una,
- * then the retransmit timer is cleared (if there are no more
- * outstanding segments) or reset to the base value (if there
- * are more ACKs expected). Whenever the retransmit timer goes off,
- * we retransmit one unacknowledged segment, and do a backoff
- * on the retransmit timer.
- *
- * The TCPT_PERSIST timer is used to keep window size information
- * flowing even if the window goes shut. If all previous transmissions
- * have been acknowledged (so that there are no retransmissions in progress),
- * and the window is too small to bother sending anything, then we start
- * the TCPT_PERSIST timer. When it expires, if the window is nonzero,
- * we go to transmit state. Otherwise, at intervals send a single byte
- * into the peer's window to force him to update our window information.
- * We do this at most as often as TCPT_PERSMIN time intervals,
- * but no more frequently than the current estimate of round-trip
- * packet time. The TCPT_PERSIST timer is cleared whenever we receive
- * a window update from the peer.
- *
- * The TCPT_KEEP timer is used to keep connections alive. If an
- * connection is idle (no segments received) for TCPTV_KEEP_INIT amount of time,
- * but not yet established, then we drop the connection. Once the connection
- * is established, if the connection is idle for TCPTV_KEEP_IDLE time
- * (and keepalives have been enabled on the socket), we begin to probe
- * the connection. We force the peer to send us a segment by sending:
- * <SEQ=SND.UNA-1><ACK=RCV.NXT><CTL=ACK>
- * This segment is (deliberately) outside the window, and should elicit
- * an ack segment in response from the peer. If, despite the TCPT_KEEP
- * initiated segments we cannot elicit a response from a peer in TCPT_MAXIDLE
- * amount of time probing, then we drop the connection.
- */
- /*
- * Time constants.
- */
- #define TCPTV_MSL ( 30*PR_SLOWHZ) /* max seg lifetime (hah!) */
- #define TCPTV_SRTTBASE 0 /* base roundtrip time;
- if 0, no idea yet */
- #define TCPTV_SRTTDFLT ( 3*PR_SLOWHZ) /* assumed RTT if no info */
- #define TCPTV_PERSMIN ( 5*PR_SLOWHZ) /* retransmit persistence */
- #define TCPTV_PERSMAX ( 60*PR_SLOWHZ) /* maximum persist interval */
- #define TCPTV_KEEP_INIT ( 75*PR_SLOWHZ) /* initial connect keep alive */
- #define TCPTV_KEEP_IDLE (120*60*PR_SLOWHZ) /* dflt time before probing */
- #define TCPTV_KEEPINTVL ( 75*PR_SLOWHZ) /* default probe interval */
- #define TCPTV_KEEPCNT 8 /* max probes before drop */
- #define TCPTV_MIN ( 1*PR_SLOWHZ) /* minimum allowable value */
- #define TCPTV_REXMTMAX ( 64*PR_SLOWHZ) /* max allowable REXMT value */
- #define TCP_LINGERTIME 120 /* linger at most 2 minutes */
- #define TCP_MAXRXTSHIFT 12 /* maximum retransmits */
- #define TCP_DELACK_TICKS (hz / PR_FASTHZ) /* time to delay ACK */
- #ifdef TCPTIMERS
- const char *tcptimers[] =
- { "REXMT", "PERSIST", "KEEP", "2MSL" };
- #endif /* TCPTIMERS */
- /*
- * Init, arm, disarm, and test TCP timers.
- */
- #define TCP_TIMER_INIT(tp, timer) \
- timeout_set(&(tp)->t_timer[(timer)], tcp_timer_funcs[(timer)], tp)
- #define TCP_TIMER_ARM(tp, timer, nticks) \
- timeout_add(&(tp)->t_timer[(timer)], (nticks) * (hz / PR_SLOWHZ))
- #define TCP_TIMER_DISARM(tp, timer) \
- timeout_del(&(tp)->t_timer[(timer)])
- #define TCP_TIMER_ISARMED(tp, timer) \
- timeout_pending(&(tp)->t_timer[(timer)])
- /*
- * Force a time value to be in a certain range.
- */
- #define TCPT_RANGESET(tv, value, tvmin, tvmax) \
- do { \
- (tv) = (value); \
- if ((tv) < (tvmin)) \
- (tv) = (tvmin); \
- else if ((tv) > (tvmax)) \
- (tv) = (tvmax); \
- } while (/* CONSTCOND */ 0)
- #ifdef _KERNEL
- typedef void (*tcp_timer_func_t)(void *);
- extern const tcp_timer_func_t tcp_timer_funcs[TCPT_NTIMERS];
- extern int tcptv_keep_init;
- extern int tcp_always_keepalive; /* assume SO_KEEPALIVE is always set */
- extern int tcp_keepidle; /* time before keepalive probes begin */
- extern int tcp_keepintvl; /* time between keepalive probes */
- extern int tcp_maxidle; /* time to drop after starting probes */
- extern int tcp_ttl; /* time to live for TCP segs */
- extern int tcp_backoff[];
- void tcp_timer_init(void);
- #endif /* _KERNEL */
- #endif /* _NETINET_TCP_TIMER_H_ */
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