| 1 | /* $NetBSD: tcp_timer.h,v 1.28 2011/05/24 18:37:52 gdt Exp $ */ |
| 2 | |
| 3 | /*- |
| 4 | * Copyright (c) 2001, 2005 The NetBSD Foundation, Inc. |
| 5 | * All rights reserved. |
| 6 | * |
| 7 | * This code is derived from software contributed to The NetBSD Foundation |
| 8 | * by Jason R. Thorpe of Wasabi Systems, Inc. |
| 9 | * This code is derived from software contributed to The NetBSD Foundation |
| 10 | * by Charles M. Hannum. |
| 11 | * |
| 12 | * Redistribution and use in source and binary forms, with or without |
| 13 | * modification, are permitted provided that the following conditions |
| 14 | * are met: |
| 15 | * 1. Redistributions of source code must retain the above copyright |
| 16 | * notice, this list of conditions and the following disclaimer. |
| 17 | * 2. Redistributions in binary form must reproduce the above copyright |
| 18 | * notice, this list of conditions and the following disclaimer in the |
| 19 | * documentation and/or other materials provided with the distribution. |
| 20 | * |
| 21 | * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS |
| 22 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED |
| 23 | * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| 24 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS |
| 25 | * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| 26 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| 27 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| 28 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| 29 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| 30 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| 31 | * POSSIBILITY OF SUCH DAMAGE. |
| 32 | */ |
| 33 | |
| 34 | /* |
| 35 | * Copyright (c) 1982, 1986, 1993 |
| 36 | * The Regents of the University of California. All rights reserved. |
| 37 | * |
| 38 | * Redistribution and use in source and binary forms, with or without |
| 39 | * modification, are permitted provided that the following conditions |
| 40 | * are met: |
| 41 | * 1. Redistributions of source code must retain the above copyright |
| 42 | * notice, this list of conditions and the following disclaimer. |
| 43 | * 2. Redistributions in binary form must reproduce the above copyright |
| 44 | * notice, this list of conditions and the following disclaimer in the |
| 45 | * documentation and/or other materials provided with the distribution. |
| 46 | * 3. 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 | */ |
| 64 | |
| 65 | #ifndef _NETINET_TCP_TIMER_H_ |
| 66 | #define _NETINET_TCP_TIMER_H_ |
| 67 | |
| 68 | /* |
| 69 | * Definitions of the TCP timers. These timers are counted |
| 70 | * down PR_SLOWHZ times a second. |
| 71 | */ |
| 72 | #define TCPT_NTIMERS 4 |
| 73 | |
| 74 | #define TCPT_REXMT 0 /* retransmit */ |
| 75 | #define TCPT_PERSIST 1 /* retransmit persistance */ |
| 76 | #define TCPT_KEEP 2 /* keep alive */ |
| 77 | #define TCPT_2MSL 3 /* 2*msl quiet time timer */ |
| 78 | |
| 79 | /* |
| 80 | * The TCPT_REXMT timer is used to force retransmissions. |
| 81 | * The TCP has the TCPT_REXMT timer set whenever segments |
| 82 | * have been sent for which ACKs are expected but not yet |
| 83 | * received. If an ACK is received which advances tp->snd_una, |
| 84 | * then the retransmit timer is cleared (if there are no more |
| 85 | * outstanding segments) or reset to the base value (if there |
| 86 | * are more ACKs expected). Whenever the retransmit timer goes off, |
| 87 | * we retransmit one unacknowledged segment, and do a backoff |
| 88 | * on the retransmit timer. |
| 89 | * |
| 90 | * The TCPT_PERSIST timer is used to keep window size information |
| 91 | * flowing even if the window goes shut. If all previous transmissions |
| 92 | * have been acknowledged (so that there are no retransmissions in progress), |
| 93 | * and the window is too small to bother sending anything, then we start |
| 94 | * the TCPT_PERSIST timer. When it expires, if the window is nonzero, |
| 95 | * we go to transmit state. Otherwise, at intervals send a single byte |
| 96 | * into the peer's window to force him to update our window information. |
| 97 | * We do this at most as often as TCPT_PERSMIN time intervals, |
| 98 | * but no more frequently than the current estimate of round-trip |
| 99 | * packet time. The TCPT_PERSIST timer is cleared whenever we receive |
| 100 | * a window update from the peer. |
| 101 | * |
| 102 | * The TCPT_KEEP timer is used to keep connections alive. If an |
| 103 | * connection is idle (no segments received) for TCPTV_KEEP_INIT amount of time, |
| 104 | * but not yet established, then we drop the connection. Once the connection |
| 105 | * is established, if the connection is idle for TCPTV_KEEP_IDLE time |
| 106 | * (and keepalives have been enabled on the socket), we begin to probe |
| 107 | * the connection. We force the peer to send us a segment by sending: |
| 108 | * <SEQ=SND.UNA-1><ACK=RCV.NXT><CTL=ACK> |
| 109 | * This segment is (deliberately) outside the window, and should elicit |
| 110 | * an ack segment in response from the peer. If, despite the TCPT_KEEP |
| 111 | * initiated segments we cannot elicit a response from a peer in TCPT_MAXIDLE |
| 112 | * amount of time probing, then we drop the connection. |
| 113 | */ |
| 114 | |
| 115 | /* |
| 116 | * Time constants. |
| 117 | * All TCPTV_* constants are in units of slow ticks (typically 500 ms). |
| 118 | */ |
| 119 | #define TCPTV_MSL ( 30*PR_SLOWHZ) /* max seg lifetime (hah!) */ |
| 120 | #define TCPTV_SRTTBASE 0 /* base roundtrip time; |
| 121 | if 0, no idea yet */ |
| 122 | #define TCPTV_SRTTDFLT ( 3*PR_SLOWHZ) /* assumed RTT if no info */ |
| 123 | |
| 124 | #define TCPTV_PERSMIN ( 5*PR_SLOWHZ) /* retransmit persistance */ |
| 125 | #define TCPTV_PERSMAX ( 60*PR_SLOWHZ) /* maximum persist interval */ |
| 126 | |
| 127 | #define TCPTV_KEEP_INIT ( 75*PR_SLOWHZ) /* initial connect keep alive */ |
| 128 | #define TCPTV_KEEP_IDLE (120*60*PR_SLOWHZ) /* dflt time before probing */ |
| 129 | #define TCPTV_KEEPINTVL ( 75*PR_SLOWHZ) /* default probe interval */ |
| 130 | #define TCPTV_KEEPCNT 8 /* max probes before drop */ |
| 131 | |
| 132 | #define TCPTV_MIN ( 1*PR_SLOWHZ) /* minimum allowable value */ |
| 133 | #define TCPTV_REXMTMAX ( 64*PR_SLOWHZ) /* max allowable REXMT value */ |
| 134 | |
| 135 | #define TCP_LINGERTIME 120 /* linger at most 2 minutes */ |
| 136 | |
| 137 | #define TCP_MAXRXTSHIFT 12 /* maximum retransmits */ |
| 138 | |
| 139 | /* Acks are delayed for 1 second; constant is in fast ticks. */ |
| 140 | #define TCP_DELACK_TICKS (hz / PR_FASTHZ) /* time to delay ACK */ |
| 141 | |
| 142 | #ifdef TCPTIMERS |
| 143 | const char *tcptimers[] = |
| 144 | { "REXMT" , "PERSIST" , "KEEP" , "2MSL" }; |
| 145 | #endif |
| 146 | |
| 147 | /* |
| 148 | * Init, arm, disarm, and test TCP timers. |
| 149 | */ |
| 150 | #define TCP_TIMER_INIT(tp, timer) \ |
| 151 | callout_setfunc(&(tp)->t_timer[(timer)], \ |
| 152 | tcp_timer_funcs[(timer)], (tp)) |
| 153 | |
| 154 | /* |
| 155 | * nticks is given in units of slow timeouts, |
| 156 | * typically 500 ms (with PR_SLOWHZ at 2). |
| 157 | */ |
| 158 | #define TCP_TIMER_ARM(tp, timer, nticks) \ |
| 159 | callout_schedule(&(tp)->t_timer[(timer)], \ |
| 160 | (nticks) * (hz / PR_SLOWHZ)) |
| 161 | |
| 162 | #define TCP_TIMER_DISARM(tp, timer) \ |
| 163 | callout_stop(&(tp)->t_timer[(timer)]) |
| 164 | |
| 165 | #define TCP_TIMER_ISARMED(tp, timer) \ |
| 166 | callout_active(&(tp)->t_timer[(timer)]) |
| 167 | |
| 168 | /* |
| 169 | * Force a time value to be in a certain range. |
| 170 | */ |
| 171 | #define TCPT_RANGESET(tv, value, tvmin, tvmax) { \ |
| 172 | (tv) = (value); \ |
| 173 | if ((tv) < (tvmin)) \ |
| 174 | (tv) = (tvmin); \ |
| 175 | if ((tv) > (tvmax)) \ |
| 176 | (tv) = (tvmax); \ |
| 177 | } |
| 178 | |
| 179 | #ifdef _KERNEL |
| 180 | typedef void (*tcp_timer_func_t)(void *); |
| 181 | |
| 182 | extern const tcp_timer_func_t tcp_timer_funcs[TCPT_NTIMERS]; |
| 183 | |
| 184 | extern u_int tcp_keepinit; /* time before initial connection times out */ |
| 185 | extern u_int tcp_keepidle; /* time before keepalive probes begin */ |
| 186 | extern u_int tcp_keepintvl; /* time between keepalive probes */ |
| 187 | extern u_int tcp_keepcnt; /* number of keepalives, 0=infty */ |
| 188 | extern int tcp_maxpersistidle; /* max idle time in persist */ |
| 189 | extern int tcp_ttl; /* time to live for TCP segs */ |
| 190 | extern const int tcp_backoff[]; |
| 191 | |
| 192 | void tcp_timer_init(void); |
| 193 | #endif |
| 194 | |
| 195 | #endif /* !_NETINET_TCP_TIMER_H_ */ |
| 196 | |