tcp_timer.h revision 1.18
1 /* $NetBSD: tcp_timer.h,v 1.18 2003/02/03 23:51:04 thorpej Exp $ */ 2 3 /*- 4 * Copyright (c) 2001 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 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the NetBSD 21 * Foundation, Inc. and its contributors. 22 * 4. Neither the name of The NetBSD Foundation nor the names of its 23 * contributors may be used to endorse or promote products derived 24 * from this software without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 36 * POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39 /* 40 * Copyright (c) 1982, 1986, 1993 41 * The Regents of the University of California. All rights reserved. 42 * 43 * Redistribution and use in source and binary forms, with or without 44 * modification, are permitted provided that the following conditions 45 * are met: 46 * 1. Redistributions of source code must retain the above copyright 47 * notice, this list of conditions and the following disclaimer. 48 * 2. Redistributions in binary form must reproduce the above copyright 49 * notice, this list of conditions and the following disclaimer in the 50 * documentation and/or other materials provided with the distribution. 51 * 3. All advertising materials mentioning features or use of this software 52 * must display the following acknowledgement: 53 * This product includes software developed by the University of 54 * California, Berkeley and its contributors. 55 * 4. Neither the name of the University nor the names of its contributors 56 * may be used to endorse or promote products derived from this software 57 * without specific prior written permission. 58 * 59 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 60 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 61 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 62 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 63 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 64 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 65 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 66 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 67 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 68 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 69 * SUCH DAMAGE. 70 * 71 * @(#)tcp_timer.h 8.1 (Berkeley) 6/10/93 72 */ 73 74 #ifndef _NETINET_TCP_TIMER_H_ 75 #define _NETINET_TCP_TIMER_H_ 76 77 /* 78 * Definitions of the TCP timers. These timers are counted 79 * down PR_SLOWHZ times a second. 80 */ 81 #define TCPT_NTIMERS 4 82 83 #define TCPT_REXMT 0 /* retransmit */ 84 #define TCPT_PERSIST 1 /* retransmit persistance */ 85 #define TCPT_KEEP 2 /* keep alive */ 86 #define TCPT_2MSL 3 /* 2*msl quiet time timer */ 87 88 /* 89 * The TCPT_REXMT timer is used to force retransmissions. 90 * The TCP has the TCPT_REXMT timer set whenever segments 91 * have been sent for which ACKs are expected but not yet 92 * received. If an ACK is received which advances tp->snd_una, 93 * then the retransmit timer is cleared (if there are no more 94 * outstanding segments) or reset to the base value (if there 95 * are more ACKs expected). Whenever the retransmit timer goes off, 96 * we retransmit one unacknowledged segment, and do a backoff 97 * on the retransmit timer. 98 * 99 * The TCPT_PERSIST timer is used to keep window size information 100 * flowing even if the window goes shut. If all previous transmissions 101 * have been acknowledged (so that there are no retransmissions in progress), 102 * and the window is too small to bother sending anything, then we start 103 * the TCPT_PERSIST timer. When it expires, if the window is nonzero, 104 * we go to transmit state. Otherwise, at intervals send a single byte 105 * into the peer's window to force him to update our window information. 106 * We do this at most as often as TCPT_PERSMIN time intervals, 107 * but no more frequently than the current estimate of round-trip 108 * packet time. The TCPT_PERSIST timer is cleared whenever we receive 109 * a window update from the peer. 110 * 111 * The TCPT_KEEP timer is used to keep connections alive. If an 112 * connection is idle (no segments received) for TCPTV_KEEP_INIT amount of time, 113 * but not yet established, then we drop the connection. Once the connection 114 * is established, if the connection is idle for TCPTV_KEEP_IDLE time 115 * (and keepalives have been enabled on the socket), we begin to probe 116 * the connection. We force the peer to send us a segment by sending: 117 * <SEQ=SND.UNA-1><ACK=RCV.NXT><CTL=ACK> 118 * This segment is (deliberately) outside the window, and should elicit 119 * an ack segment in response from the peer. If, despite the TCPT_KEEP 120 * initiated segments we cannot elicit a response from a peer in TCPT_MAXIDLE 121 * amount of time probing, then we drop the connection. 122 */ 123 124 /* 125 * Time constants. 126 */ 127 #define TCPTV_MSL ( 30*PR_SLOWHZ) /* max seg lifetime (hah!) */ 128 #define TCPTV_SRTTBASE 0 /* base roundtrip time; 129 if 0, no idea yet */ 130 #define TCPTV_SRTTDFLT ( 3*PR_SLOWHZ) /* assumed RTT if no info */ 131 132 #define TCPTV_PERSMIN ( 5*PR_SLOWHZ) /* retransmit persistance */ 133 #define TCPTV_PERSMAX ( 60*PR_SLOWHZ) /* maximum persist interval */ 134 135 #define TCPTV_KEEP_INIT ( 75*PR_SLOWHZ) /* initial connect keep alive */ 136 #define TCPTV_KEEP_IDLE (120*60*PR_SLOWHZ) /* dflt time before probing */ 137 #define TCPTV_KEEPINTVL ( 75*PR_SLOWHZ) /* default probe interval */ 138 #define TCPTV_KEEPCNT 8 /* max probes before drop */ 139 140 #define TCPTV_MIN ( 1*PR_SLOWHZ) /* minimum allowable value */ 141 #define TCPTV_REXMTMAX ( 64*PR_SLOWHZ) /* max allowable REXMT value */ 142 143 #define TCP_LINGERTIME 120 /* linger at most 2 minutes */ 144 145 #define TCP_MAXRXTSHIFT 12 /* maximum retransmits */ 146 147 #define TCP_DELACK_TICKS (hz / PR_FASTHZ) /* time to delay ACK */ 148 149 #ifdef TCPTIMERS 150 char *tcptimers[] = 151 { "REXMT", "PERSIST", "KEEP", "2MSL" }; 152 #endif 153 154 /* 155 * Init, arm, disarm, and test TCP timers. 156 */ 157 #define TCP_TIMER_INIT(tp, timer) \ 158 callout_init(&(tp)->t_timer[(timer)]) 159 160 #define TCP_TIMER_ARM(tp, timer, nticks) \ 161 callout_reset(&(tp)->t_timer[(timer)], \ 162 (nticks) * (hz / PR_SLOWHZ), tcp_timer_funcs[(timer)], tp) 163 164 #define TCP_TIMER_DISARM(tp, timer) \ 165 callout_stop(&(tp)->t_timer[(timer)]) 166 167 #define TCP_TIMER_ISARMED(tp, timer) \ 168 callout_pending(&(tp)->t_timer[(timer)]) 169 170 /* 171 * Force a time value to be in a certain range. 172 */ 173 #define TCPT_RANGESET(tv, value, tvmin, tvmax) { \ 174 (tv) = (value); \ 175 if ((tv) < (tvmin)) \ 176 (tv) = (tvmin); \ 177 else if ((tv) > (tvmax)) \ 178 (tv) = (tvmax); \ 179 } 180 181 #ifdef _KERNEL 182 typedef void (*tcp_timer_func_t)(void *); 183 184 extern const tcp_timer_func_t tcp_timer_funcs[TCPT_NTIMERS]; 185 186 extern int tcp_keepidle; /* time before keepalive probes begin */ 187 extern int tcp_keepintvl; /* time between keepalive probes */ 188 extern int tcp_keepcnt; /* number of keepalives, 0=infty */ 189 extern int tcp_maxpersistidle; /* max idle time in persist */ 190 extern int tcp_maxidle; /* time to drop after starting probes */ 191 extern int tcp_ttl; /* time to live for TCP segs */ 192 extern const int tcp_backoff[]; 193 194 void tcp_timer_init(void); 195 #endif 196 197 #endif /* _NETINET_TCP_TIMER_H_ */ 198
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