tcp_time.h

VRTX 商用嵌入式实时操作系统

/***************************************************************************
*
*               Copyright (c) 1993 READY SYSTEMS CORPORATION.
*
*       All rights reserved. READY SYSTEMS' source code is an unpublished
*       work and the use of a copyright notice does not imply otherwise.
*       This source code contains confidential, trade secret material of
*       READY SYSTEMS. Any attempt or participation in deciphering, decoding,
*       reverse engineering or in any way altering the source code is
*       strictly prohibited, unless the prior written consent of
*       READY SYSTEMS is obtained.
*
*
*       Module Name:            tcp_time.h
*
*       Identification:         @(#) 1.3 tcp_time.h
*
*       Date:                   1/6/94  16:37:24
*
****************************************************************************
*/

/*
 RCS header identifier - $Id: tcp_time.h,v 1.6 1993/10/05 18:08:52 robert Exp $
*/
/*
 * Copyrighted as an unpublished work.
 * (c) Copyright 1987-1993 Lachman Technology, Incorporated
 * All rights reserved.
 * 
 * RESTRICTED RIGHTS
 * 
 * These programs are supplied under a license.  They may be used,
 * disclosed, and/or copied only as permitted under such license
 * agreement.  Any copy must contain the above copyright notice and
 * this restricted rights notice.  Use, copying, and/or disclosure
 * of the programs is strictly prohibited unless otherwise provided
 * in the license agreement.
 */
/*
 * Copyright (c) 1982, 1986 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that this notice is preserved and that due credit is given
 * to the University of California at Berkeley. The name of the University
 * may not be used to endorse or promote products derived from this
 * software without specific prior written permission. This software
 * is provided ``as is'' without express or implied warranty.
 *
 *	@(#)tcp_timer.h	7.5 (Berkeley) 3/16/88
 */
#ifndef tcp_timer_h
#define tcp_timer_h

#ifdef __cplusplus
extern "C" {
#endif

/*
 * Definitions of the TCP timers.  These timers are counted down PR_SLOWHZ
 * times a second. 
 */
#define	TCPT_NTIMERS	6

#define	TCPT_REXMT	0	/* retransmit */
#define	TCPT_PERSIST	1	/* retransmit persistance */
#define	TCPT_KEEP	2	/* keep alive */
#define	TCPT_2MSL	3	/* 2*msl quiet time timer */
#define	TCPT_LINGER	4	/* linger on close imer */
#define TCPT_DEQUEUE	5	/* call tcp_calldeq() to send data upstream */

/*
 * 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.
 */

#define	TCP_TTL		60	/* default time to live for TCP segs */
/*
 * 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 persistance */
#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 */

#ifdef	TCPTIMERS
STATIC char           *tcptimers[] =
{"REXMT", "PERSIST", "KEEP", "2MSL", "LINGER", "DEQUEUE"};
#endif

/*
 * Force a time value to be in a certain range. 
 */
#define	TCPT_RANGESET(tv, value, tvmin, tvmax) { \
	(tv) = (value); \
	if ((tv) < (tvmin)) \
		(tv) = (tvmin); \
	else if ((tv) > (tvmax)) \
		(tv) = (tvmax); \
}

#ifdef KERNEL
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[];
#endif

#ifdef __cplusplus
}
#endif

#endif				/* tcp_timer_h */