1 /* $NetBSD: tcp_timer.h,v 1.20 2003/08/07 16:33:19 agc 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_ */
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