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1 | /* |
2 | * Copyright (c) 1982, 1986 Regents of the University of California. | |
3 | * All rights reserved. | |
4 | * | |
5 | * Redistribution and use in source and binary forms, with or without | |
6 | * modification, are permitted provided that the following conditions | |
7 | * are met: | |
8 | * 1. Redistributions of source code must retain the above copyright | |
9 | * notice, this list of conditions and the following disclaimer. | |
10 | * 2. Redistributions in binary form must reproduce the above copyright | |
11 | * notice, this list of conditions and the following disclaimer in the | |
12 | * documentation and/or other materials provided with the distribution. | |
13 | * 3. All advertising materials mentioning features or use of this software | |
14 | * must display the following acknowledgement: | |
15 | * This product includes software developed by the University of | |
16 | * California, Berkeley and its contributors. | |
17 | * 4. Neither the name of the University nor the names of its contributors | |
18 | * may be used to endorse or promote products derived from this software | |
19 | * without specific prior written permission. | |
20 | * | |
21 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND | |
22 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
23 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
24 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | |
25 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
26 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
27 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
28 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
29 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
30 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
31 | * SUCH DAMAGE. | |
32 | * | |
38e82238 | 33 | * from: @(#)tcp_timer.h 7.8 (Berkeley) 6/28/90 |
4c45483e | 34 | * $Id: tcp_timer.h,v 1.3 1993/11/07 17:48:10 wollman Exp $ |
15637ed4 RG |
35 | */ |
36 | ||
8ace4366 GW |
37 | #ifndef _NETINET_TCP_TIMER_H_ |
38 | #define _NETINET_TCP_TIMER_H_ 1 | |
39 | ||
15637ed4 RG |
40 | /* |
41 | * Definitions of the TCP timers. These timers are counted | |
42 | * down PR_SLOWHZ times a second. | |
43 | */ | |
44 | #define TCPT_NTIMERS 4 | |
45 | ||
46 | #define TCPT_REXMT 0 /* retransmit */ | |
47 | #define TCPT_PERSIST 1 /* retransmit persistance */ | |
48 | #define TCPT_KEEP 2 /* keep alive */ | |
49 | #define TCPT_2MSL 3 /* 2*msl quiet time timer */ | |
50 | ||
51 | /* | |
52 | * The TCPT_REXMT timer is used to force retransmissions. | |
53 | * The TCP has the TCPT_REXMT timer set whenever segments | |
54 | * have been sent for which ACKs are expected but not yet | |
55 | * received. If an ACK is received which advances tp->snd_una, | |
56 | * then the retransmit timer is cleared (if there are no more | |
57 | * outstanding segments) or reset to the base value (if there | |
58 | * are more ACKs expected). Whenever the retransmit timer goes off, | |
59 | * we retransmit one unacknowledged segment, and do a backoff | |
60 | * on the retransmit timer. | |
61 | * | |
62 | * The TCPT_PERSIST timer is used to keep window size information | |
63 | * flowing even if the window goes shut. If all previous transmissions | |
64 | * have been acknowledged (so that there are no retransmissions in progress), | |
65 | * and the window is too small to bother sending anything, then we start | |
66 | * the TCPT_PERSIST timer. When it expires, if the window is nonzero, | |
67 | * we go to transmit state. Otherwise, at intervals send a single byte | |
68 | * into the peer's window to force him to update our window information. | |
69 | * We do this at most as often as TCPT_PERSMIN time intervals, | |
70 | * but no more frequently than the current estimate of round-trip | |
71 | * packet time. The TCPT_PERSIST timer is cleared whenever we receive | |
72 | * a window update from the peer. | |
73 | * | |
74 | * The TCPT_KEEP timer is used to keep connections alive. If an | |
75 | * connection is idle (no segments received) for TCPTV_KEEP_INIT amount of time, | |
76 | * but not yet established, then we drop the connection. Once the connection | |
77 | * is established, if the connection is idle for TCPTV_KEEP_IDLE time | |
78 | * (and keepalives have been enabled on the socket), we begin to probe | |
79 | * the connection. We force the peer to send us a segment by sending: | |
80 | * <SEQ=SND.UNA-1><ACK=RCV.NXT><CTL=ACK> | |
81 | * This segment is (deliberately) outside the window, and should elicit | |
82 | * an ack segment in response from the peer. If, despite the TCPT_KEEP | |
83 | * initiated segments we cannot elicit a response from a peer in TCPT_MAXIDLE | |
84 | * amount of time probing, then we drop the connection. | |
85 | */ | |
86 | ||
87 | #define TCP_TTL 60 /* default time to live for TCP segs */ | |
88 | /* | |
89 | * Time constants. | |
90 | */ | |
91 | #define TCPTV_MSL ( 30*PR_SLOWHZ) /* max seg lifetime (hah!) */ | |
92 | #define TCPTV_SRTTBASE 0 /* base roundtrip time; | |
93 | if 0, no idea yet */ | |
94 | #define TCPTV_SRTTDFLT ( 3*PR_SLOWHZ) /* assumed RTT if no info */ | |
95 | ||
96 | #define TCPTV_PERSMIN ( 5*PR_SLOWHZ) /* retransmit persistance */ | |
97 | #define TCPTV_PERSMAX ( 60*PR_SLOWHZ) /* maximum persist interval */ | |
98 | ||
99 | #define TCPTV_KEEP_INIT ( 75*PR_SLOWHZ) /* initial connect keep alive */ | |
100 | #define TCPTV_KEEP_IDLE (120*60*PR_SLOWHZ) /* dflt time before probing */ | |
101 | #define TCPTV_KEEPINTVL ( 75*PR_SLOWHZ) /* default probe interval */ | |
102 | #define TCPTV_KEEPCNT 8 /* max probes before drop */ | |
103 | ||
104 | #define TCPTV_MIN ( 1*PR_SLOWHZ) /* minimum allowable value */ | |
105 | #define TCPTV_REXMTMAX ( 64*PR_SLOWHZ) /* max allowable REXMT value */ | |
106 | ||
107 | #define TCP_LINGERTIME 120 /* linger at most 2 minutes */ | |
108 | ||
109 | #define TCP_MAXRXTSHIFT 12 /* maximum retransmits */ | |
110 | ||
111 | #ifdef TCPTIMERS | |
4c45483e | 112 | const char *tcptimers[] = |
15637ed4 RG |
113 | { "REXMT", "PERSIST", "KEEP", "2MSL" }; |
114 | #endif | |
115 | ||
116 | /* | |
117 | * Force a time value to be in a certain range. | |
118 | */ | |
119 | #define TCPT_RANGESET(tv, value, tvmin, tvmax) { \ | |
120 | (tv) = (value); \ | |
4c45483e | 121 | if ((u_long)(tv) < (u_long)(tvmin)) \ |
15637ed4 | 122 | (tv) = (tvmin); \ |
4c45483e | 123 | else if ((u_long)(tv) > (u_long)(tvmax)) \ |
15637ed4 RG |
124 | (tv) = (tvmax); \ |
125 | } | |
126 | ||
127 | #ifdef KERNEL | |
128 | extern int tcp_keepidle; /* time before keepalive probes begin */ | |
129 | extern int tcp_keepintvl; /* time between keepalive probes */ | |
130 | extern int tcp_maxidle; /* time to drop after starting probes */ | |
131 | extern int tcp_ttl; /* time to live for TCP segs */ | |
132 | extern int tcp_backoff[]; | |
133 | #endif | |
8ace4366 | 134 | #endif /* _NETINET_TCP_TIMER_H_ */ |