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comparison packages/net/bsd_tcpip/current/include/netinet/tcp_timer.h @ 208:e0c0827131d1 ecos

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Merge from eCos master repository on 2002-05-20-20:11:54-BST
author jlarmour
date Mon, 20 May 2002 22:19:26 +0000
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children d578891243fd
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207:74c807ddde34 208:e0c0827131d1
1 //==========================================================================
2 //
3 // include/netinet/tcp_timer.h
4 //
5 //==========================================================================
6 //####BSDCOPYRIGHTBEGIN####
7 //
8 // -------------------------------------------
9 //
10 // Portions of this software may have been derived from OpenBSD,
11 // FreeBSD or other sources, and are covered by the appropriate
12 // copyright disclaimers included herein.
13 //
14 // Portions created by Red Hat are
15 // Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
16 //
17 // -------------------------------------------
18 //
19 //####BSDCOPYRIGHTEND####
20 //==========================================================================
21
22 /*
23 * Copyright (c) 1982, 1986, 1993
24 * The Regents of the University of California. All rights reserved.
25 *
26 * Redistribution and use in source and binary forms, with or without
27 * modification, are permitted provided that the following conditions
28 * are met:
29 * 1. Redistributions of source code must retain the above copyright
30 * notice, this list of conditions and the following disclaimer.
31 * 2. Redistributions in binary form must reproduce the above copyright
32 * notice, this list of conditions and the following disclaimer in the
33 * documentation and/or other materials provided with the distribution.
34 * 3. All advertising materials mentioning features or use of this software
35 * must display the following acknowledgement:
36 * This product includes software developed by the University of
37 * California, Berkeley and its contributors.
38 * 4. Neither the name of the University nor the names of its contributors
39 * may be used to endorse or promote products derived from this software
40 * without specific prior written permission.
41 *
42 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
43 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
44 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
45 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
46 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
47 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
48 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
49 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
50 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
51 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
52 * SUCH DAMAGE.
53 *
54 * @(#)tcp_timer.h 8.1 (Berkeley) 6/10/93
55 * $FreeBSD: src/sys/netinet/tcp_timer.h,v 1.18 1999/12/29 04:41:03 peter Exp $
56 */
57
58 #ifndef _NETINET_TCP_TIMER_H_
59 #define _NETINET_TCP_TIMER_H_
60
61 /*
62 * The TCPT_REXMT timer is used to force retransmissions.
63 * The TCP has the TCPT_REXMT timer set whenever segments
64 * have been sent for which ACKs are expected but not yet
65 * received. If an ACK is received which advances tp->snd_una,
66 * then the retransmit timer is cleared (if there are no more
67 * outstanding segments) or reset to the base value (if there
68 * are more ACKs expected). Whenever the retransmit timer goes off,
69 * we retransmit one unacknowledged segment, and do a backoff
70 * on the retransmit timer.
71 *
72 * The TCPT_PERSIST timer is used to keep window size information
73 * flowing even if the window goes shut. If all previous transmissions
74 * have been acknowledged (so that there are no retransmissions in progress),
75 * and the window is too small to bother sending anything, then we start
76 * the TCPT_PERSIST timer. When it expires, if the window is nonzero,
77 * we go to transmit state. Otherwise, at intervals send a single byte
78 * into the peer's window to force him to update our window information.
79 * We do this at most as often as TCPT_PERSMIN time intervals,
80 * but no more frequently than the current estimate of round-trip
81 * packet time. The TCPT_PERSIST timer is cleared whenever we receive
82 * a window update from the peer.
83 *
84 * The TCPT_KEEP timer is used to keep connections alive. If an
85 * connection is idle (no segments received) for TCPTV_KEEP_INIT amount of time,
86 * but not yet established, then we drop the connection. Once the connection
87 * is established, if the connection is idle for TCPTV_KEEP_IDLE time
88 * (and keepalives have been enabled on the socket), we begin to probe
89 * the connection. We force the peer to send us a segment by sending:
90 * <SEQ=SND.UNA-1><ACK=RCV.NXT><CTL=ACK>
91 * This segment is (deliberately) outside the window, and should elicit
92 * an ack segment in response from the peer. If, despite the TCPT_KEEP
93 * initiated segments we cannot elicit a response from a peer in TCPT_MAXIDLE
94 * amount of time probing, then we drop the connection.
95 */
96
97 /*
98 * Time constants.
99 */
100 #define TCPTV_MSL ( 30*hz) /* max seg lifetime (hah!) */
101 #define TCPTV_SRTTBASE 0 /* base roundtrip time;
102 if 0, no idea yet */
103 #define TCPTV_RTOBASE ( 3*hz) /* assumed RTO if no info */
104 #define TCPTV_SRTTDFLT ( 3*hz) /* assumed RTT if no info */
105
106 #define TCPTV_PERSMIN ( 5*hz) /* retransmit persistence */
107 #define TCPTV_PERSMAX ( 60*hz) /* maximum persist interval */
108
109 #define TCPTV_KEEP_INIT ( 75*hz) /* initial connect keepalive */
110 #define TCPTV_KEEP_IDLE (120*60*hz) /* dflt time before probing */
111 #define TCPTV_KEEPINTVL ( 75*hz) /* default probe interval */
112 #define TCPTV_KEEPCNT 8 /* max probes before drop */
113
114 #define TCPTV_MIN ( 1*hz) /* minimum allowable value */
115 #define TCPTV_REXMTMAX ( 64*hz) /* max allowable REXMT value */
116
117 #define TCPTV_TWTRUNC 8 /* RTO factor to truncate TW */
118
119 #define TCP_LINGERTIME 120 /* linger at most 2 minutes */
120
121 #define TCP_MAXRXTSHIFT 12 /* maximum retransmits */
122
123 #define TCPTV_DELACK (hz / PR_FASTHZ / 2) /* 100ms timeout */
124
125 #ifdef TCPTIMERS
126 static char *tcptimers[] =
127 { "REXMT", "PERSIST", "KEEP", "2MSL" };
128 #endif
129
130 /*
131 * Force a time value to be in a certain range.
132 */
133 #define TCPT_RANGESET(tv, value, tvmin, tvmax) do { \
134 (tv) = (value); \
135 if ((u_long)(tv) < (u_long)(tvmin)) \
136 (tv) = (tvmin); \
137 else if ((u_long)(tv) > (u_long)(tvmax)) \
138 (tv) = (tvmax); \
139 } while(0)
140
141 #ifdef _KERNEL
142 extern int tcp_keepinit; /* time to establish connection */
143 extern int tcp_keepidle; /* time before keepalive probes begin */
144 extern int tcp_keepintvl; /* time between keepalive probes */
145 extern int tcp_maxidle; /* time to drop after starting probes */
146 extern int tcp_delacktime; /* time before sending a delayed ACK */
147 extern int tcp_maxpersistidle;
148 extern int tcp_msl;
149 extern int tcp_ttl; /* time to live for TCP segs */
150 extern int tcp_backoff[];
151
152 void tcp_timer_2msl __P((void *xtp));
153 void tcp_timer_keep __P((void *xtp));
154 void tcp_timer_persist __P((void *xtp));
155 void tcp_timer_rexmt __P((void *xtp));
156 void tcp_timer_delack __P((void *xtp));
157
158 #endif /* _KERNEL */
159
160 #endif /* !_NETINET_TCP_TIMER_H_ */