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1.1 root 1: /*
2: * Copyright (c) 1982, 1986, 1993
3: * The Regents of the University of California. 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: *
33: * @(#)tcp_timer.h 8.1 (Berkeley) 6/10/93
34: * tcp_timer.h,v 1.4 1994/08/21 05:27:38 paul Exp
35: */
36:
37: #ifndef _TCP_TIMER_H_
38: #define _TCP_TIMER_H_
39:
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 persistence */
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: /*
88: * Time constants.
89: */
90: #define TCPTV_MSL ( 5*PR_SLOWHZ) /* max seg lifetime (hah!) */
91:
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 persistence */
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: #define TCPTV_REXMTMAX ( 12*PR_SLOWHZ) /* max allowable REXMT value */
107:
108: #define TCP_LINGERTIME 120 /* linger at most 2 minutes */
109:
110: #define TCP_MAXRXTSHIFT 12 /* maximum retransmits */
111:
112:
113: #ifdef TCPTIMERS
114: char *tcptimers[] =
115: { "REXMT", "PERSIST", "KEEP", "2MSL" };
116: #endif
117:
118: /*
119: * Force a time value to be in a certain range.
120: */
121: #define TCPT_RANGESET(tv, value, tvmin, tvmax) { \
122: (tv) = (value); \
123: if ((tv) < (tvmin)) \
124: (tv) = (tvmin); \
125: else if ((tv) > (tvmax)) \
126: (tv) = (tvmax); \
127: }
128:
1.1.1.2 ! root 129: extern const int tcp_backoff[];
1.1 root 130:
131: struct tcpcb;
132:
133: void tcp_fasttimo _P((void));
134: void tcp_slowtimo _P((void));
135: void tcp_canceltimers _P((struct tcpcb *));
136:
137: #endif
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