![[BACK]](/cvsweb/icons/back.gif){kind=icon}
Return to tcp_timer.h CVS log ![[TXT]](/cvsweb/icons/text.gif){kind=icon}
![[DIR]](/cvsweb/icons/dir.gif){kind=icon}
Up to [Apple XNU] / XNU / bsd / netinet|
Return to tcp_timer.h CVS log | Up to [Apple XNU] / XNU / bsd / netinet |
1.1 root 1: /*
2: * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
3: *
4: * @APPLE_LICENSE_HEADER_START@
5: *
6: * The contents of this file constitute Original Code as defined in and
7: * are subject to the Apple Public Source License Version 1.1 (the
8: * "License"). You may not use this file except in compliance with the
9: * License. Please obtain a copy of the License at
10: * http://www.apple.com/publicsource and read it before using this file.
11: *
12: * This Original Code and all software distributed under the License are
13: * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
14: * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
15: * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
16: * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the
17: * License for the specific language governing rights and limitations
18: * under the License.
19: *
20: * @APPLE_LICENSE_HEADER_END@
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: */
56:
57: #ifndef _NETINET_TCP_TIMER_H_
58: #define _NETINET_TCP_TIMER_H_
59:
60: /*
61: * Definitions of the TCP timers. These timers are counted
62: * down PR_SLOWHZ times a second.
63: */
64: #define TCPT_NTIMERS 4
65:
66: #define TCPT_REXMT 0 /* retransmit */
67: #define TCPT_PERSIST 1 /* retransmit persistence */
68: #define TCPT_KEEP 2 /* keep alive */
69: #define TCPT_2MSL 3 /* 2*msl quiet time timer */
70:
71: /*
72: * The TCPT_REXMT timer is used to force retransmissions.
73: * The TCP has the TCPT_REXMT timer set whenever segments
74: * have been sent for which ACKs are expected but not yet
75: * received. If an ACK is received which advances tp->snd_una,
76: * then the retransmit timer is cleared (if there are no more
77: * outstanding segments) or reset to the base value (if there
78: * are more ACKs expected). Whenever the retransmit timer goes off,
79: * we retransmit one unacknowledged segment, and do a backoff
80: * on the retransmit timer.
81: *
82: * The TCPT_PERSIST timer is used to keep window size information
83: * flowing even if the window goes shut. If all previous transmissions
84: * have been acknowledged (so that there are no retransmissions in progress),
85: * and the window is too small to bother sending anything, then we start
86: * the TCPT_PERSIST timer. When it expires, if the window is nonzero,
87: * we go to transmit state. Otherwise, at intervals send a single byte
88: * into the peer's window to force him to update our window information.
89: * We do this at most as often as TCPT_PERSMIN time intervals,
90: * but no more frequently than the current estimate of round-trip
91: * packet time. The TCPT_PERSIST timer is cleared whenever we receive
92: * a window update from the peer.
93: *
94: * The TCPT_KEEP timer is used to keep connections alive. If an
95: * connection is idle (no segments received) for TCPTV_KEEP_INIT amount of time,
96: * but not yet established, then we drop the connection. Once the connection
97: * is established, if the connection is idle for TCPTV_KEEP_IDLE time
98: * (and keepalives have been enabled on the socket), we begin to probe
99: * the connection. We force the peer to send us a segment by sending:
100: * <SEQ=SND.UNA-1><ACK=RCV.NXT><CTL=ACK>
101: * This segment is (deliberately) outside the window, and should elicit
102: * an ack segment in response from the peer. If, despite the TCPT_KEEP
103: * initiated segments we cannot elicit a response from a peer in TCPT_MAXIDLE
104: * amount of time probing, then we drop the connection.
105: */
106:
107: /*
108: * Time constants.
109: */
110: #define TCPTV_MSL ( 30*PR_SLOWHZ) /* max seg lifetime (hah!) */
111: #define TCPTV_SRTTBASE 0 /* base roundtrip time;
112: if 0, no idea yet */
113: #define TCPTV_RTOBASE ( 3*PR_SLOWHZ) /* assumed RTO if no info */
114: #define TCPTV_SRTTDFLT ( 3*PR_SLOWHZ) /* assumed RTT if no info */
115:
116: #define TCPTV_PERSMIN ( 5*PR_SLOWHZ) /* retransmit persistence */
117: #define TCPTV_PERSMAX ( 60*PR_SLOWHZ) /* maximum persist interval */
118:
119: #define TCPTV_KEEP_INIT ( 75*PR_SLOWHZ) /* initial connect keep alive */
120: #define TCPTV_KEEP_IDLE (120*60*PR_SLOWHZ) /* dflt time before probing */
121: #define TCPTV_KEEPINTVL ( 75*PR_SLOWHZ) /* default probe interval */
122: #define TCPTV_KEEPCNT 8 /* max probes before drop */
123:
124: #define TCPTV_MIN ( 1*PR_SLOWHZ) /* minimum allowable value */
125: #define TCPTV_REXMTMAX ( 64*PR_SLOWHZ) /* max allowable REXMT value */
126:
127: #define TCPTV_TWTRUNC 8 /* RTO factor to truncate TW */
128:
129: #define TCP_LINGERTIME 120 /* linger at most 2 minutes */
130:
131: #define TCP_MAXRXTSHIFT 12 /* maximum retransmits */
132:
133: #ifdef TCPTIMERS
134: static char *tcptimers[] =
135: { "REXMT", "PERSIST", "KEEP", "2MSL" };
136: #endif
137:
138: /*
139: * Force a time value to be in a certain range.
140: */
141: #define TCPT_RANGESET(tv, value, tvmin, tvmax) { \
142: (tv) = (value); \
143: if ((u_long)(tv) < (u_long)(tvmin)) \
144: (tv) = (tvmin); \
145: else if ((u_long)(tv) > (u_long)(tvmax)) \
146: (tv) = (tvmax); \
147: }
148:
149: #ifdef KERNEL
150: extern int tcp_keepinit; /* time to establish connection */
151: extern int tcp_keepidle; /* time before keepalive probes begin */
152: extern int tcp_maxidle; /* time to drop after starting probes */
153: extern int tcp_ttl; /* time to live for TCP segs */
154: extern int tcp_backoff[];
155: #endif
156:
157: #endif
This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.