bsd/netinet/tcp_timer.h

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*
  26  * Copyright (c) 1982, 1986, 1993
  27  *      The Regents of the University of California.  All rights reserved.
  28  *
  29  * Redistribution and use in source and binary forms, with or without
  30  * modification, are permitted provided that the following conditions
  31  * are met:
  32  * 1. Redistributions of source code must retain the above copyright
  33  *    notice, this list of conditions and the following disclaimer.
  34  * 2. Redistributions in binary form must reproduce the above copyright
  35  *    notice, this list of conditions and the following disclaimer in the
  36  *    documentation and/or other materials provided with the distribution.
  37  * 3. All advertising materials mentioning features or use of this software
  38  *    must display the following acknowledgement:
  39  *      This product includes software developed by the University of
  40  *      California, Berkeley and its contributors.
  41  * 4. Neither the name of the University nor the names of its contributors
  42  *    may be used to endorse or promote products derived from this software
  43  *    without specific prior written permission.
  44  *
  45  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  46  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  47  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  48  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  49  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  50  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  51  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  52  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  53  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  54  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  55  * SUCH DAMAGE.
  56  *
  57  *      @(#)tcp_timer.h 8.1 (Berkeley) 6/10/93
  58  * $FreeBSD: src/sys/netinet/tcp_timer.h,v 1.18 1999/12/29 04:41:03 peter Exp $
  59  */
  60
  61 #ifndef _NETINET_TCP_TIMER_H_
  62 #define _NETINET_TCP_TIMER_H_
  63 #include <sys/appleapiopts.h>
  64
  65 /*
  66  * Definitions of the TCP timers.  These timers are counted
  67  * down PR_SLOWHZ times a second.
  68  */
  69 #define TCPT_NTIMERS    4
  70
  71 #define TCPT_REXMT      0               /* retransmit */
  72 #define TCPT_PERSIST    1               /* retransmit persistence */
  73 #define TCPT_KEEP       2               /* keep alive */
  74 #define TCPT_2MSL       3               /* 2*msl quiet time timer */
  75
  76 /*
  77  * The TCPT_REXMT timer is used to force retransmissions.
  78  * The TCP has the TCPT_REXMT timer set whenever segments
  79  * have been sent for which ACKs are expected but not yet
  80  * received.  If an ACK is received which advances tp->snd_una,
  81  * then the retransmit timer is cleared (if there are no more
  82  * outstanding segments) or reset to the base value (if there
  83  * are more ACKs expected).  Whenever the retransmit timer goes off,
  84  * we retransmit one unacknowledged segment, and do a backoff
  85  * on the retransmit timer.
  86  *
  87  * The TCPT_PERSIST timer is used to keep window size information
  88  * flowing even if the window goes shut.  If all previous transmissions
  89  * have been acknowledged (so that there are no retransmissions in progress),
  90  * and the window is too small to bother sending anything, then we start
  91  * the TCPT_PERSIST timer.  When it expires, if the window is nonzero,
  92  * we go to transmit state.  Otherwise, at intervals send a single byte
  93  * into the peer's window to force him to update our window information.
  94  * We do this at most as often as TCPT_PERSMIN time intervals,
  95  * but no more frequently than the current estimate of round-trip
  96  * packet time.  The TCPT_PERSIST timer is cleared whenever we receive
  97  * a window update from the peer.
  98  *
  99  * The TCPT_KEEP timer is used to keep connections alive.  If an
 100  * connection is idle (no segments received) for TCPTV_KEEP_INIT amount of time,
 101  * but not yet established, then we drop the connection.  Once the connection
 102  * is established, if the connection is idle for TCPTV_KEEP_IDLE time
 103  * (and keepalives have been enabled on the socket), we begin to probe
 104  * the connection.  We force the peer to send us a segment by sending:
 105  *      <SEQ=SND.UNA-1><ACK=RCV.NXT><CTL=ACK>
 106  * This segment is (deliberately) outside the window, and should elicit
 107  * an ack segment in response from the peer.  If, despite the TCPT_KEEP
 108  * initiated segments we cannot elicit a response from a peer in TCPT_MAXIDLE
 109  * amount of time probing, then we drop the connection.
 110  */
 111
 112 /*
 113  * Time constants.
 114  */
 115 #ifdef __APPLE_API_PRIVATE
 116 #define TCPTV_MSL       ( 30*PR_SLOWHZ)         /* max seg lifetime (hah!) */
 117 #define TCPTV_SRTTBASE  0                       /* base roundtrip time;
 118                                                    if 0, no idea yet */
 119 #define TCPTV_RTOBASE   (  3*PR_SLOWHZ)         /* assumed RTO if no info */
 120 #define TCPTV_SRTTDFLT  (  3*PR_SLOWHZ)         /* assumed RTT if no info */
 121
 122 #define TCPTV_PERSMIN   (  5*PR_SLOWHZ)         /* retransmit persistence */
 123 #define TCPTV_PERSMAX   ( 60*PR_SLOWHZ)         /* maximum persist interval */
 124
 125 #define TCPTV_KEEP_INIT ( 75*PR_SLOWHZ)         /* initial connect keep alive */
 126 #define TCPTV_KEEP_IDLE (120*60*PR_SLOWHZ)      /* dflt time before probing */
 127 #define TCPTV_KEEPINTVL ( 75*PR_SLOWHZ)         /* default probe interval */
 128 #define TCPTV_KEEPCNT   8                       /* max probes before drop */
 129
 130 #define TCPTV_MIN       (  1*PR_SLOWHZ)         /* minimum allowable value */
 131 #define TCPTV_REXMTMAX  ( 64*PR_SLOWHZ)         /* max allowable REXMT value */
 132
 133 #define TCPTV_TWTRUNC   8                       /* RTO factor to truncate TW */
 134
 135 #define TCP_LINGERTIME  120                     /* linger at most 2 minutes */
 136
 137 #define TCP_MAXRXTSHIFT 12                      /* maximum retransmits */
 138
 139 #define TCPTV_DELACK    PR_FASTHZ               /* 125ms timeout */
 140
 141 #ifdef  TCPTIMERS
 142 static char *tcptimers[] =
 143     { "REXMT", "PERSIST", "KEEP", "2MSL" };
 144 #endif
 145
 146 /*
 147  * Force a time value to be in a certain range.
 148  */
 149 #define TCPT_RANGESET(tv, value, tvmin, tvmax) do { \
 150         (tv) = (value); \
 151         if ((u_long)(tv) < (u_long)(tvmin)) \
 152                 (tv) = (tvmin); \
 153         else if ((u_long)(tv) > (u_long)(tvmax)) \
 154                 (tv) = (tvmax); \
 155 } while(0)
 156
 157 #ifdef KERNEL
 158 extern int tcp_keepinit;                /* time to establish connection */
 159 extern int tcp_keepidle;                /* time before keepalive probes begin */
 160 extern int tcp_keepintvl;               /* time between keepalive probes */
 161 extern int tcp_maxidle;                 /* time to drop after starting probes */
 162 extern int tcp_delacktime;              /* time before sending a delayed ACK */
 163 extern int tcp_maxpersistidle;
 164 extern int tcp_msl;
 165 extern int tcp_ttl;                     /* time to live for TCP segs */
 166 extern int tcp_backoff[];
 167
 168 void    tcp_timer_2msl __P((void *xtp));
 169 void    tcp_timer_keep __P((void *xtp));
 170 void    tcp_timer_persist __P((void *xtp));
 171 void    tcp_timer_rexmt __P((void *xtp));
 172 void    tcp_timer_delack __P((void *xtp));
 173
 174 #endif /* KERNEL */
 175 #endif /* __APPLE_API_PRIVATE */
 176
 177 #endif /* !_NETINET_TCP_TIMER_H_ */