1 /* $NetBSD: tcp_timer.h,v 1.30 2019/08/06 15:48:18 riastradh 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 #define TCP_TIMER_MAXTICKS \ 169 (INT_MAX / (hz / PR_SLOWHZ)) 170 171 #define TCP_MAXMSL \ 172 (TCP_TIMER_MAXTICKS / 2) 173 174 /* 175 * Force a time value to be in a certain range. 176 */ 177 #define TCPT_RANGESET(tv, value, tvmin, tvmax) { \ 178 (tv) = (value); \ 179 if ((tv) < (tvmin)) \ 180 (tv) = (tvmin); \ 181 if ((tv) > (tvmax)) \ 182 (tv) = (tvmax); \ 183 } 184 185 #ifdef _KERNEL 186 typedef void (*tcp_timer_func_t)(void *); 187 188 extern const tcp_timer_func_t tcp_timer_funcs[TCPT_NTIMERS]; 189 190 extern u_int tcp_keepinit; /* time before initial connection times out */ 191 extern u_int tcp_keepidle; /* time before keepalive probes begin */ 192 extern u_int tcp_keepintvl; /* time between keepalive probes */ 193 extern u_int tcp_keepcnt; /* number of keepalives, 0=infty */ 194 extern int tcp_maxpersistidle; /* max idle time in persist */ 195 extern int tcp_ttl; /* time to live for TCP segs */ 196 extern const int tcp_backoff[]; 197 198 void tcp_timer_init(void); 199 void tcp_slowtimo_init(void); 200 #endif 201 202 #endif /* !_NETINET_TCP_TIMER_H_ */ 203