tcp_timer.h revision 1.19.2.1
1 /* $NetBSD: tcp_timer.h,v 1.19.2.1 2004/08/03 10:54:46 skrll 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. Neither the name of the University nor the names of its contributors 52 * may be used to endorse or promote products derived from this software 53 * without specific prior written permission. 54 * 55 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 56 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 57 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 58 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 59 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 60 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 61 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 62 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 63 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 64 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 65 * SUCH DAMAGE. 66 * 67 * @(#)tcp_timer.h 8.1 (Berkeley) 6/10/93 68 */ 69 70 #ifndef _NETINET_TCP_TIMER_H_ 71 #define _NETINET_TCP_TIMER_H_ 72 73 /* 74 * Definitions of the TCP timers. These timers are counted 75 * down PR_SLOWHZ times a second. 76 */ 77 #define TCPT_NTIMERS 4 78 79 #define TCPT_REXMT 0 /* retransmit */ 80 #define TCPT_PERSIST 1 /* retransmit persistance */ 81 #define TCPT_KEEP 2 /* keep alive */ 82 #define TCPT_2MSL 3 /* 2*msl quiet time timer */ 83 84 /* 85 * The TCPT_REXMT timer is used to force retransmissions. 86 * The TCP has the TCPT_REXMT timer set whenever segments 87 * have been sent for which ACKs are expected but not yet 88 * received. If an ACK is received which advances tp->snd_una, 89 * then the retransmit timer is cleared (if there are no more 90 * outstanding segments) or reset to the base value (if there 91 * are more ACKs expected). Whenever the retransmit timer goes off, 92 * we retransmit one unacknowledged segment, and do a backoff 93 * on the retransmit timer. 94 * 95 * The TCPT_PERSIST timer is used to keep window size information 96 * flowing even if the window goes shut. If all previous transmissions 97 * have been acknowledged (so that there are no retransmissions in progress), 98 * and the window is too small to bother sending anything, then we start 99 * the TCPT_PERSIST timer. When it expires, if the window is nonzero, 100 * we go to transmit state. Otherwise, at intervals send a single byte 101 * into the peer's window to force him to update our window information. 102 * We do this at most as often as TCPT_PERSMIN time intervals, 103 * but no more frequently than the current estimate of round-trip 104 * packet time. The TCPT_PERSIST timer is cleared whenever we receive 105 * a window update from the peer. 106 * 107 * The TCPT_KEEP timer is used to keep connections alive. If an 108 * connection is idle (no segments received) for TCPTV_KEEP_INIT amount of time, 109 * but not yet established, then we drop the connection. Once the connection 110 * is established, if the connection is idle for TCPTV_KEEP_IDLE time 111 * (and keepalives have been enabled on the socket), we begin to probe 112 * the connection. We force the peer to send us a segment by sending: 113 * <SEQ=SND.UNA-1><ACK=RCV.NXT><CTL=ACK> 114 * This segment is (deliberately) outside the window, and should elicit 115 * an ack segment in response from the peer. If, despite the TCPT_KEEP 116 * initiated segments we cannot elicit a response from a peer in TCPT_MAXIDLE 117 * amount of time probing, then we drop the connection. 118 */ 119 120 /* 121 * Time constants. 122 */ 123 #define TCPTV_MSL ( 30*PR_SLOWHZ) /* max seg lifetime (hah!) */ 124 #define TCPTV_SRTTBASE 0 /* base roundtrip time; 125 if 0, no idea yet */ 126 #define TCPTV_SRTTDFLT ( 3*PR_SLOWHZ) /* assumed RTT if no info */ 127 128 #define TCPTV_PERSMIN ( 5*PR_SLOWHZ) /* retransmit persistance */ 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 TCP_LINGERTIME 120 /* linger at most 2 minutes */ 140 141 #define TCP_MAXRXTSHIFT 12 /* maximum retransmits */ 142 143 #define TCP_DELACK_TICKS (hz / PR_FASTHZ) /* time to delay ACK */ 144 145 #ifdef TCPTIMERS 146 char *tcptimers[] = 147 { "REXMT", "PERSIST", "KEEP", "2MSL" }; 148 #endif 149 150 /* 151 * Init, arm, disarm, and test TCP timers. 152 */ 153 #define TCP_TIMER_INIT(tp, timer) \ 154 callout_setfunc(&(tp)->t_timer[(timer)], \ 155 tcp_timer_funcs[(timer)], (tp)) 156 157 #define TCP_TIMER_ARM(tp, timer, nticks) \ 158 callout_schedule(&(tp)->t_timer[(timer)], \ 159 (nticks) * (hz / PR_SLOWHZ)) 160 161 #define TCP_TIMER_DISARM(tp, timer) \ 162 callout_stop(&(tp)->t_timer[(timer)]) 163 164 #define TCP_TIMER_ISARMED(tp, timer) \ 165 callout_pending(&(tp)->t_timer[(timer)]) 166 167 /* 168 * Force a time value to be in a certain range. 169 */ 170 #define TCPT_RANGESET(tv, value, tvmin, tvmax) { \ 171 (tv) = (value); \ 172 if ((tv) < (tvmin)) \ 173 (tv) = (tvmin); \ 174 else if ((tv) > (tvmax)) \ 175 (tv) = (tvmax); \ 176 } 177 178 #ifdef _KERNEL 179 typedef void (*tcp_timer_func_t)(void *); 180 181 extern const tcp_timer_func_t tcp_timer_funcs[TCPT_NTIMERS]; 182 183 extern int tcp_keepidle; /* time before keepalive probes begin */ 184 extern int tcp_keepintvl; /* time between keepalive probes */ 185 extern int tcp_keepcnt; /* number of keepalives, 0=infty */ 186 extern int tcp_maxpersistidle; /* max idle time in persist */ 187 extern int tcp_maxidle; /* time to drop after starting probes */ 188 extern int tcp_ttl; /* time to live for TCP segs */ 189 extern const int tcp_backoff[]; 190 191 void tcp_timer_init(void); 192 #endif 193 194 #endif /* _NETINET_TCP_TIMER_H_ */ 195
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