LCOM1920-T02G10

/*        $NetBSD: tcp_timer.h,v 1.28 2011/05/24 18:37:52 gdt Exp $        */

/*-

 * Copyright (c) 2001, 2005 The NetBSD Foundation, Inc.

 * All rights reserved.

 *

 * This code is derived from software contributed to The NetBSD Foundation

 * by Jason R. Thorpe of Wasabi Systems, Inc.

 * This code is derived from software contributed to The NetBSD Foundation

 * by Charles M. Hannum.

 *

 * 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.

 *

 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.

 */

/*

 * 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 persistance */

#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.

 * All TCPTV_* constants are in units of slow ticks (typically 500 ms).

 */

#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 */

/* Acks are delayed for 1 second; constant is in fast ticks. */

#define        TCP_DELACK_TICKS (hz / PR_FASTHZ)        /* time to delay ACK */

#ifdef        TCPTIMERS

const char *tcptimers[] =

    { "REXMT", "PERSIST", "KEEP", "2MSL" };

#endif

/*

 * Init, arm, disarm, and test TCP timers.

 */

#define        TCP_TIMER_INIT(tp, timer)                                        \

        callout_setfunc(&(tp)->t_timer[(timer)],                        \

            tcp_timer_funcs[(timer)], (tp))

/*

 * nticks is given in units of slow timeouts,

 * typically 500 ms (with PR_SLOWHZ at 2).

 */

#define        TCP_TIMER_ARM(tp, timer, nticks)                                \

        callout_schedule(&(tp)->t_timer[(timer)],                        \

            (nticks) * (hz / PR_SLOWHZ))

#define        TCP_TIMER_DISARM(tp, timer)                                        \

        callout_stop(&(tp)->t_timer[(timer)])

#define        TCP_TIMER_ISARMED(tp, timer)                                        \

        callout_active(&(tp)->t_timer[(timer)])

/*

 * Force a time value to be in a certain range.

 */

#define        TCPT_RANGESET(tv, value, tvmin, tvmax) { \

        (tv) = (value); \

        if ((tv) < (tvmin)) \

                (tv) = (tvmin); \

        if ((tv) > (tvmax)) \

                (tv) = (tvmax); \

}

#ifdef _KERNEL

typedef void (*tcp_timer_func_t)(void *);

extern const tcp_timer_func_t tcp_timer_funcs[TCPT_NTIMERS];

extern u_int tcp_keepinit;                /* time before initial connection times out */

extern u_int tcp_keepidle;                /* time before keepalive probes begin */

extern u_int tcp_keepintvl;                /* time between keepalive probes */

extern u_int tcp_keepcnt;                /* number of keepalives, 0=infty */

extern int tcp_maxpersistidle;                /* max idle time in persist */

extern int tcp_ttl;                        /* time to live for TCP segs */

extern const int tcp_backoff[];

void        tcp_timer_init(void);

#endif

#endif /* !_NETINET_TCP_TIMER_H_ */