IABSD.fr/src/sys/netinet/tcp_timer.h

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• Author : bluhm
  Date : 2025-01-16 11:59:20
  Hash : e835bce2
  Message : Remove net lock from TCP sysctl for keep alive. Keep copies in seconds for the sysctl and update timer variables atomically when they change. tcp_maxidle was historically calculated in tcp_slowtimo() as the timers were called from there. Better calculate maxidle when needed. tcp_timer_init() is useless, just initialize data. While there make the names consistent. input sthen@; OK mvs@

• sys/netinet/tcp_timer.h

• /*	$OpenBSD: tcp_timer.h,v 1.26 2025/01/16 11:59:20 bluhm 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.
   */
  #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 */
  #define	TCPT_DELACK	4		/* delayed ack timeout */
  
  #define	TCPT_NTIMERS	5
  
  /*
   * 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	TCP_TIME(30)	/* max seg lifetime (hah!) */
  #define	TCPTV_SRTTBASE	0		/* base roundtrip time;
  					   if 0, no idea yet */
  #define	TCPTV_SRTTDFLT	TCP_TIME(3)	/* assumed RTT if no info */
  
  #define	TCPTV_PERSMIN	TCP_TIME(5)	/* retransmit persistence */
  #define	TCPTV_PERSMAX	TCP_TIME(60)	/* maximum persist interval */
  
  #define	TCPTV_KEEPINIT	TCP_TIME(75)	/* initial connect keep alive */
  #define	TCPTV_KEEPIDLE	TCP_TIME(120*60) /* dflt time before probing */
  #define	TCPTV_KEEPINTVL	TCP_TIME(75)	/* default probe interval */
  #define	TCPTV_KEEPCNT	8		/* max probes before drop */
  
  #define	TCPTV_MIN	TCP_TIME(1)	/* minimum allowable value */
  #define	TCPTV_REXMTMAX	TCP_TIME(64)	/* max allowable REXMT value */
  
  #define	TCP_LINGERTIME	120		/* linger at most 2 minutes */
  
  #define	TCP_MAXRXTSHIFT	12		/* maximum retransmits */
  
  #define	TCP_DELACK_MSECS 200		/* time to delay ACK */
  
  #ifdef	TCPTIMERS
  const char *tcptimers[TCPT_NTIMERS] =
      { "REXMT", "PERSIST", "KEEP", "2MSL", "DELACK" };
  #endif /* TCPTIMERS */
  
  /*
   * Init, arm, disarm, and test TCP timers.
   */
  #define	TCP_TIMER_INIT(tp, timer)					\
  	timeout_set_flags(&(tp)->t_timer[(timer)],			\
  	    tcp_timer_funcs[(timer)], (tp)->t_inpcb,			\
  	    KCLOCK_NONE, TIMEOUT_PROC | TIMEOUT_MPSAFE)
  
  #define	TCP_TIMER_ARM(tp, timer, msecs)					\
  do {									\
  	SET((tp)->t_flags, TF_TIMER << (timer));			\
  	if (timeout_add_msec(&(tp)->t_timer[(timer)], (msecs)))		\
  		in_pcbref((tp)->t_inpcb);				\
  } while (0)
  
  #define	TCP_TIMER_DISARM(tp, timer)					\
  do {									\
  	CLR((tp)->t_flags, TF_TIMER << (timer));			\
  	if (timeout_del(&(tp)->t_timer[(timer)]))			\
  		in_pcbunref((tp)->t_inpcb);				\
  } while (0)
  
  #define	TCP_TIMER_ISARMED(tp, timer)					\
  	ISSET((tp)->t_flags, TF_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 tcp_delack_msecs;	/* [I] delayed ACK timeout in millisecs */
  extern int tcp_always_keepalive;/* [a] assume SO_KEEPALIVE always set */
  extern int tcp_keepinit;	/* [a] time to keep alive initial SYN packet */
  extern int tcp_keepidle;	/* [a] time before keepalive probes begin */
  extern int tcp_keepintvl;	/* [a] time between keepalive probes */
  extern int tcp_keepinit_sec;	/* [a] copy of above in seconds for sysctl */
  extern int tcp_keepidle_sec;	/* [a] copy of above in seconds for sysctl */
  extern int tcp_keepintvl_sec;	/* [a] copy of above in seconds for sysctl */
  extern int tcp_ttl;		/* time to live for TCP segs */
  extern const int tcp_backoff[];
  
  void	tcp_timer_reaper(void *);
  
  #endif /* _KERNEL */
  #endif /* _NETINET_TCP_TIMER_H_ */