bsd/netns/spp_timer.h

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  * Copyright (c) 1982, 1986, 1988, 1993
  24  *      The Regents of the University of California.  All rights reserved.
  25  *
  26  * Redistribution and use in source and binary forms, with or without
  27  * modification, are permitted provided that the following conditions
  28  * are met:
  29  * 1. Redistributions of source code must retain the above copyright
  30  *    notice, this list of conditions and the following disclaimer.
  31  * 2. Redistributions in binary form must reproduce the above copyright
  32  *    notice, this list of conditions and the following disclaimer in the
  33  *    documentation and/or other materials provided with the distribution.
  34  * 3. All advertising materials mentioning features or use of this software
  35  *    must display the following acknowledgement:
  36  *      This product includes software developed by the University of
  37  *      California, Berkeley and its contributors.
  38  * 4. Neither the name of the University nor the names of its contributors
  39  *    may be used to endorse or promote products derived from this software
  40  *    without specific prior written permission.
  41  *
  42  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  43  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  44  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  45  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  46  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  47  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  48  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  49  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  50  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  51  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  52  * SUCH DAMAGE.
  53  *
  54  *      @(#)spp_timer.h 8.1 (Berkeley) 6/10/93
  55  */
  56
  57 /*
  58  * Definitions of the SPP timers.  These timers are counted
  59  * down PR_SLOWHZ times a second.
  60  */
  61 #define SPPT_NTIMERS    4
  62
  63 #define SPPT_REXMT      0               /* retransmit */
  64 #define SPPT_PERSIST    1               /* retransmit persistance */
  65 #define SPPT_KEEP       2               /* keep alive */
  66 #define SPPT_2MSL       3               /* 2*msl quiet time timer */
  67
  68 /*
  69  * The SPPT_REXMT timer is used to force retransmissions.
  70  * The SPP has the SPPT_REXMT timer set whenever segments
  71  * have been sent for which ACKs are expected but not yet
  72  * received.  If an ACK is received which advances tp->snd_una,
  73  * then the retransmit timer is cleared (if there are no more
  74  * outstanding segments) or reset to the base value (if there
  75  * are more ACKs expected).  Whenever the retransmit timer goes off,
  76  * we retransmit one unacknowledged segment, and do a backoff
  77  * on the retransmit timer.
  78  *
  79  * The SPPT_PERSIST timer is used to keep window size information
  80  * flowing even if the window goes shut.  If all previous transmissions
  81  * have been acknowledged (so that there are no retransmissions in progress),
  82  * and the window is too small to bother sending anything, then we start
  83  * the SPPT_PERSIST timer.  When it expires, if the window is nonzero,
  84  * we go to transmit state.  Otherwise, at intervals send a single byte
  85  * into the peer's window to force him to update our window information.
  86  * We do this at most as often as SPPT_PERSMIN time intervals,
  87  * but no more frequently than the current estimate of round-trip
  88  * packet time.  The SPPT_PERSIST timer is cleared whenever we receive
  89  * a window update from the peer.
  90  *
  91  * The SPPT_KEEP timer is used to keep connections alive.  If an
  92  * connection is idle (no segments received) for SPPTV_KEEP amount of time,
  93  * but not yet established, then we drop the connection.  If the connection
  94  * is established, then we force the peer to send us a segment by sending:
  95  *      <SEQ=SND.UNA-1><ACK=RCV.NXT><CTL=ACK>
  96  * This segment is (deliberately) outside the window, and should elicit
  97  * an ack segment in response from the peer.  If, despite the SPPT_KEEP
  98  * initiated segments we cannot elicit a response from a peer in SPPT_MAXIDLE
  99  * amount of time, then we drop the connection.
 100  */
 101
 102 #define SPP_TTL         30              /* default time to live for SPP segs */
 103 /*
 104  * Time constants.
 105  */
 106 #define SPPTV_MSL       ( 15*PR_SLOWHZ)         /* max seg lifetime */
 107 #define SPPTV_SRTTBASE  0                       /* base roundtrip time;
 108                                                    if 0, no idea yet */
 109 #define SPPTV_SRTTDFLT  (  3*PR_SLOWHZ)         /* assumed RTT if no info */
 110
 111 #define SPPTV_PERSMIN   (  5*PR_SLOWHZ)         /* retransmit persistance */
 112 #define SPPTV_PERSMAX   ( 60*PR_SLOWHZ)         /* maximum persist interval */
 113
 114 #define SPPTV_KEEP      ( 75*PR_SLOWHZ)         /* keep alive - 75 secs */
 115 #define SPPTV_MAXIDLE   (  8*SPPTV_KEEP)        /* maximum allowable idle
 116                                                    time before drop conn */
 117
 118 #define SPPTV_MIN       (  1*PR_SLOWHZ)         /* minimum allowable value */
 119 #define SPPTV_REXMTMAX  ( 64*PR_SLOWHZ)         /* max allowable REXMT value */
 120
 121 #define SPP_LINGERTIME  120                     /* linger at most 2 minutes */
 122
 123 #define SPP_MAXRXTSHIFT 12                      /* maximum retransmits */
 124
 125 #ifdef  SPPTIMERS
 126 char *spptimers[] =
 127     { "REXMT", "PERSIST", "KEEP", "2MSL" };
 128 #endif
 129
 130 /*
 131  * Force a time value to be in a certain range.
 132  */
 133 #define SPPT_RANGESET(tv, value, tvmin, tvmax) { \
 134         (tv) = (value); \
 135         if ((tv) < (tvmin)) \
 136                 (tv) = (tvmin); \
 137         else if ((tv) > (tvmax)) \
 138                 (tv) = (tvmax); \
 139 }
 140
 141 #ifdef KERNEL
 142 extern int spp_backoff[];
 143 #endif