1 /* $NetBSD: tcp_timer.h,v 1.21 2005/03/04 05:51:41 mycroft 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 * 3. All advertising materials mentioning features or use of this software
21 * must display the following acknowledgement:
22 * This product includes software developed by the NetBSD
23 * Foundation, Inc. and its contributors.
24 * 4. Neither the name of The NetBSD Foundation nor the names of its
25 * contributors may be used to endorse or promote products derived
26 * from this software without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
29 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
30 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
31 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
32 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
33 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
34 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
35 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
36 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
37 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
38 * POSSIBILITY OF SUCH DAMAGE.
39 */
40
41 /*
42 * Copyright (c) 1982, 1986, 1993
43 * The Regents of the University of California. All rights reserved.
44 *
45 * Redistribution and use in source and binary forms, with or without
46 * modification, are permitted provided that the following conditions
47 * are met:
48 * 1. Redistributions of source code must retain the above copyright
49 * notice, this list of conditions and the following disclaimer.
50 * 2. Redistributions in binary form must reproduce the above copyright
51 * notice, this list of conditions and the following disclaimer in the
52 * documentation and/or other materials provided with the distribution.
53 * 3. Neither the name of the University nor the names of its contributors
54 * may be used to endorse or promote products derived from this software
55 * without specific prior written permission.
56 *
57 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
58 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
59 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
60 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
61 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
62 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
63 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
64 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
65 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
66 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
67 * SUCH DAMAGE.
68 *
69 * @(#)tcp_timer.h 8.1 (Berkeley) 6/10/93
70 */
71
72 #ifndef _NETINET_TCP_TIMER_H_
73 #define _NETINET_TCP_TIMER_H_
74
75 /*
76 * Definitions of the TCP timers. These timers are counted
77 * down PR_SLOWHZ times a second.
78 */
79 #define TCPT_NTIMERS 4
80
81 #define TCPT_REXMT 0 /* retransmit */
82 #define TCPT_PERSIST 1 /* retransmit persistance */
83 #define TCPT_KEEP 2 /* keep alive */
84 #define TCPT_2MSL 3 /* 2*msl quiet time timer */
85
86 /*
87 * The TCPT_REXMT timer is used to force retransmissions.
88 * The TCP has the TCPT_REXMT timer set whenever segments
89 * have been sent for which ACKs are expected but not yet
90 * received. If an ACK is received which advances tp->snd_una,
91 * then the retransmit timer is cleared (if there are no more
92 * outstanding segments) or reset to the base value (if there
93 * are more ACKs expected). Whenever the retransmit timer goes off,
94 * we retransmit one unacknowledged segment, and do a backoff
95 * on the retransmit timer.
96 *
97 * The TCPT_PERSIST timer is used to keep window size information
98 * flowing even if the window goes shut. If all previous transmissions
99 * have been acknowledged (so that there are no retransmissions in progress),
100 * and the window is too small to bother sending anything, then we start
101 * the TCPT_PERSIST timer. When it expires, if the window is nonzero,
102 * we go to transmit state. Otherwise, at intervals send a single byte
103 * into the peer's window to force him to update our window information.
104 * We do this at most as often as TCPT_PERSMIN time intervals,
105 * but no more frequently than the current estimate of round-trip
106 * packet time. The TCPT_PERSIST timer is cleared whenever we receive
107 * a window update from the peer.
108 *
109 * The TCPT_KEEP timer is used to keep connections alive. If an
110 * connection is idle (no segments received) for TCPTV_KEEP_INIT amount of time,
111 * but not yet established, then we drop the connection. Once the connection
112 * is established, if the connection is idle for TCPTV_KEEP_IDLE time
113 * (and keepalives have been enabled on the socket), we begin to probe
114 * the connection. We force the peer to send us a segment by sending:
115 * <SEQ=SND.UNA-1><ACK=RCV.NXT><CTL=ACK>
116 * This segment is (deliberately) outside the window, and should elicit
117 * an ack segment in response from the peer. If, despite the TCPT_KEEP
118 * initiated segments we cannot elicit a response from a peer in TCPT_MAXIDLE
119 * amount of time probing, then we drop the connection.
120 */
121
122 /*
123 * Time constants.
124 */
125 #define TCPTV_MSL ( 30*PR_SLOWHZ) /* max seg lifetime (hah!) */
126 #define TCPTV_SRTTBASE 0 /* base roundtrip time;
127 if 0, no idea yet */
128 #define TCPTV_SRTTDFLT ( 3*PR_SLOWHZ) /* assumed RTT if no info */
129
130 #define TCPTV_PERSMIN ( 5*PR_SLOWHZ) /* retransmit persistance */
131 #define TCPTV_PERSMAX ( 60*PR_SLOWHZ) /* maximum persist interval */
132
133 #define TCPTV_KEEP_INIT ( 75*PR_SLOWHZ) /* initial connect keep alive */
134 #define TCPTV_KEEP_IDLE (120*60*PR_SLOWHZ) /* dflt time before probing */
135 #define TCPTV_KEEPINTVL ( 75*PR_SLOWHZ) /* default probe interval */
136 #define TCPTV_KEEPCNT 8 /* max probes before drop */
137
138 #define TCPTV_MIN ( 1*PR_SLOWHZ) /* minimum allowable value */
139 #define TCPTV_REXMTMAX ( 64*PR_SLOWHZ) /* max allowable REXMT value */
140
141 #define TCP_LINGERTIME 120 /* linger at most 2 minutes */
142
143 #define TCP_MAXRXTSHIFT 12 /* maximum retransmits */
144
145 #define TCP_DELACK_TICKS (hz / PR_FASTHZ) /* time to delay ACK */
146
147 #ifdef TCPTIMERS
148 char *tcptimers[] =
149 { "REXMT", "PERSIST", "KEEP", "2MSL" };
150 #endif
151
152 /*
153 * Init, arm, disarm, and test TCP timers.
154 */
155 #define TCP_TIMER_INIT(tp, timer) \
156 callout_setfunc(&(tp)->t_timer[(timer)], \
157 tcp_timer_funcs[(timer)], (tp))
158
159 #define TCP_TIMER_ARM(tp, timer, nticks) \
160 callout_schedule(&(tp)->t_timer[(timer)], \
161 (nticks) * (hz / PR_SLOWHZ))
162
163 #define TCP_TIMER_DISARM(tp, timer) \
164 callout_stop(&(tp)->t_timer[(timer)])
165
166 #define TCP_TIMER_ISARMED(tp, timer) \
167 callout_active(&(tp)->t_timer[(timer)])
168
169 /*
170 * Force a time value to be in a certain range.
171 */
172 #define TCPT_RANGESET(tv, value, tvmin, tvmax) { \
173 (tv) = (value); \
174 if ((tv) < (tvmin)) \
175 (tv) = (tvmin); \
176 else if ((tv) > (tvmax)) \
177 (tv) = (tvmax); \
178 }
179
180 #ifdef _KERNEL
181 typedef void (*tcp_timer_func_t)(void *);
182
183 extern const tcp_timer_func_t tcp_timer_funcs[TCPT_NTIMERS];
184
185 extern int tcp_keepidle; /* time before keepalive probes begin */
186 extern int tcp_keepintvl; /* time between keepalive probes */
187 extern int tcp_keepcnt; /* number of keepalives, 0=infty */
188 extern int tcp_maxpersistidle; /* max idle time in persist */
189 extern int tcp_maxidle; /* time to drop after starting probes */
190 extern int tcp_ttl; /* time to live for TCP segs */
191 extern const int tcp_backoff[];
192
193 void tcp_timer_init(void);
194 #endif
195
196 #endif /* _NETINET_TCP_TIMER_H_ */
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