bsd/netinet/tcp_timer.h

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_OSREFERENCE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License.  The rights granted to you under the
  10  * License may not be used to create, or enable the creation or
  11  * redistribution of, unlawful or unlicensed copies of an Apple operating
  12  * system, or to circumvent, violate, or enable the circumvention or
  13  * violation of, any terms of an Apple operating system software license
  14  * agreement.
  15  *
  16  * Please obtain a copy of the License at
  17  * http://www.opensource.apple.com/apsl/ and read it before using this
  18  * file.
  19  *
  20  * The Original Code and all software distributed under the License are
  21  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  22  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  23  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  24  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  25  * Please see the License for the specific language governing rights and
  26  * limitations under the License.
  27  *
  28  * @APPLE_LICENSE_OSREFERENCE_HEADER_END@
  29  */
  30 /*
  31  * Copyright (c) 1982, 1986, 1993
  32  *      The Regents of the University of California.  All rights reserved.
  33  *
  34  * Redistribution and use in source and binary forms, with or without
  35  * modification, are permitted provided that the following conditions
  36  * are met:
  37  * 1. Redistributions of source code must retain the above copyright
  38  *    notice, this list of conditions and the following disclaimer.
  39  * 2. Redistributions in binary form must reproduce the above copyright
  40  *    notice, this list of conditions and the following disclaimer in the
  41  *    documentation and/or other materials provided with the distribution.
  42  * 3. All advertising materials mentioning features or use of this software
  43  *    must display the following acknowledgement:
  44  *      This product includes software developed by the University of
  45  *      California, Berkeley and its contributors.
  46  * 4. Neither the name of the University nor the names of its contributors
  47  *    may be used to endorse or promote products derived from this software
  48  *    without specific prior written permission.
  49  *
  50  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  51  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  52  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  53  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  54  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  55  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  56  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  57  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  58  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  59  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  60  * SUCH DAMAGE.
  61  *
  62  *      @(#)tcp_timer.h 8.1 (Berkeley) 6/10/93
  63  * $FreeBSD: src/sys/netinet/tcp_timer.h,v 1.18 1999/12/29 04:41:03 peter Exp $
  64  */
  65
  66 #ifndef _NETINET_TCP_TIMER_H_
  67 #define _NETINET_TCP_TIMER_H_
  68 #include <sys/appleapiopts.h>
  69
  70 /*
  71  * Definitions of the TCP timers.  These timers are counted
  72  * down PR_SLOWHZ times a second.
  73  */
  74 #define TCPT_NTIMERS    4
  75
  76 #define TCPT_REXMT      0               /* retransmit */
  77 #define TCPT_PERSIST    1               /* retransmit persistence */
  78 #define TCPT_KEEP       2               /* keep alive */
  79 #define TCPT_2MSL       3               /* 2*msl quiet time timer */
  80
  81 /*
  82  * The TCPT_REXMT timer is used to force retransmissions.
  83  * The TCP has the TCPT_REXMT timer set whenever segments
  84  * have been sent for which ACKs are expected but not yet
  85  * received.  If an ACK is received which advances tp->snd_una,
  86  * then the retransmit timer is cleared (if there are no more
  87  * outstanding segments) or reset to the base value (if there
  88  * are more ACKs expected).  Whenever the retransmit timer goes off,
  89  * we retransmit one unacknowledged segment, and do a backoff
  90  * on the retransmit timer.
  91  *
  92  * The TCPT_PERSIST timer is used to keep window size information
  93  * flowing even if the window goes shut.  If all previous transmissions
  94  * have been acknowledged (so that there are no retransmissions in progress),
  95  * and the window is too small to bother sending anything, then we start
  96  * the TCPT_PERSIST timer.  When it expires, if the window is nonzero,
  97  * we go to transmit state.  Otherwise, at intervals send a single byte
  98  * into the peer's window to force him to update our window information.
  99  * We do this at most as often as TCPT_PERSMIN time intervals,
 100  * but no more frequently than the current estimate of round-trip
 101  * packet time.  The TCPT_PERSIST timer is cleared whenever we receive
 102  * a window update from the peer.
 103  *
 104  * The TCPT_KEEP timer is used to keep connections alive.  If an
 105  * connection is idle (no segments received) for TCPTV_KEEP_INIT amount of time,
 106  * but not yet established, then we drop the connection.  Once the connection
 107  * is established, if the connection is idle for TCPTV_KEEP_IDLE time
 108  * (and keepalives have been enabled on the socket), we begin to probe
 109  * the connection.  We force the peer to send us a segment by sending:
 110  *      <SEQ=SND.UNA-1><ACK=RCV.NXT><CTL=ACK>
 111  * This segment is (deliberately) outside the window, and should elicit
 112  * an ack segment in response from the peer.  If, despite the TCPT_KEEP
 113  * initiated segments we cannot elicit a response from a peer in TCPT_MAXIDLE
 114  * amount of time probing, then we drop the connection.
 115  */
 116
 117 #ifdef PRIVATE
 118
 119 /*
 120  * Time constants.
 121  */
 122 #define TCPTV_MSL       ( 30*PR_SLOWHZ)         /* max seg lifetime (hah!) */
 123 #define TCPTV_SRTTBASE  0                       /* base roundtrip time;
 124                                                    if 0, no idea yet */
 125 #define TCPTV_RTOBASE   (  3*PR_SLOWHZ)         /* assumed RTO if no info */
 126 #define TCPTV_SRTTDFLT  (  3*PR_SLOWHZ)         /* assumed RTT if no info */
 127
 128 #define TCPTV_PERSMIN   (  5*PR_SLOWHZ)         /* retransmit persistence */
 129 #define TCPTV_PERSMAX   ( 60*PR_SLOWHZ)         /* maximum persist interval */
 130
 131 #define TCPTV_KEEP_INIT ( 75*PR_SLOWHZ)         /* initial connect keep alive */
 132 #define TCPTV_KEEP_IDLE (120*60*PR_SLOWHZ)      /* dflt time before probing */
 133 #define TCPTV_KEEPINTVL ( 75*PR_SLOWHZ)         /* default probe interval */
 134 #define TCPTV_KEEPCNT   8                       /* max probes before drop */
 135
 136 #define TCPTV_MIN       (  1*PR_SLOWHZ)         /* minimum allowable value */
 137 #define TCPTV_REXMTMAX  ( 64*PR_SLOWHZ)         /* max allowable REXMT value */
 138
 139 #define TCPTV_TWTRUNC   8                       /* RTO factor to truncate TW */
 140
 141 #define TCP_LINGERTIME  120                     /* linger at most 2 minutes */
 142
 143 #define TCP_MAXRXTSHIFT 12                      /* maximum retransmits */
 144
 145 #define TCPTV_DELACK    PR_FASTHZ               /* 125ms timeout */
 146
 147 #ifdef  TCPTIMERS
 148 static char *tcptimers[] =
 149     { "REXMT", "PERSIST", "KEEP", "2MSL" };
 150 #endif
 151
 152 #ifdef KERNEL
 153 /*
 154  * Force a time value to be in a certain range.
 155  */
 156 #define TCPT_RANGESET(tv, value, tvmin, tvmax) do { \
 157         (tv) = (value); \
 158         if ((u_long)(tv) < (u_long)(tvmin)) \
 159                 (tv) = (tvmin); \
 160         else if ((u_long)(tv) > (u_long)(tvmax)) \
 161                 (tv) = (tvmax); \
 162 } while(0)
 163
 164 #define TCP_KEEPIDLE(tp) \
 165         (tp->t_keepidle && (tp->t_inpcb->inp_socket->so_options & SO_KEEPALIVE) ? \
 166                 tp->t_keepidle : tcp_keepidle)
 167
 168 extern int tcp_keepinit;                /* time to establish connection */
 169 extern int tcp_keepidle;                /* time before keepalive probes begin */
 170 extern int tcp_keepintvl;               /* time between keepalive probes */
 171 extern int tcp_maxidle;                 /* time to drop after starting probes */
 172 extern int tcp_delacktime;              /* time before sending a delayed ACK */
 173 extern int tcp_maxpersistidle;
 174 extern int tcp_msl;
 175 extern int tcp_ttl;                     /* time to live for TCP segs */
 176 extern int tcp_backoff[];
 177
 178 void    tcp_timer_2msl(void *xtp);
 179 void    tcp_timer_keep(void *xtp);
 180 void    tcp_timer_persist(void *xtp);
 181 void    tcp_timer_rexmt(void *xtp);
 182 void    tcp_timer_delack(void *xtp);
 183
 184 #endif /* KERNEL */
 185 #endif /* PRIVATE */
 186 #endif /* !_NETINET_TCP_TIMER_H_ */
 187