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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.
1.1.1.3 ! root 13: * 3. Neither the name of the University nor the names of its contributors
1.1 root 14: * may be used to endorse or promote products derived from this software
15: * without specific prior written permission.
16: *
17: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27: * SUCH DAMAGE.
28: *
29: * @(#)tcp_timer.h 8.1 (Berkeley) 6/10/93
30: * tcp_timer.h,v 1.4 1994/08/21 05:27:38 paul Exp
31: */
32:
33: #ifndef _TCP_TIMER_H_
34: #define _TCP_TIMER_H_
35:
36: /*
37: * Definitions of the TCP timers. These timers are counted
38: * down PR_SLOWHZ times a second.
39: */
40: #define TCPT_NTIMERS 4
41:
42: #define TCPT_REXMT 0 /* retransmit */
43: #define TCPT_PERSIST 1 /* retransmit persistence */
44: #define TCPT_KEEP 2 /* keep alive */
45: #define TCPT_2MSL 3 /* 2*msl quiet time timer */
46:
47: /*
48: * The TCPT_REXMT timer is used to force retransmissions.
49: * The TCP has the TCPT_REXMT timer set whenever segments
50: * have been sent for which ACKs are expected but not yet
51: * received. If an ACK is received which advances tp->snd_una,
52: * then the retransmit timer is cleared (if there are no more
53: * outstanding segments) or reset to the base value (if there
54: * are more ACKs expected). Whenever the retransmit timer goes off,
55: * we retransmit one unacknowledged segment, and do a backoff
56: * on the retransmit timer.
57: *
58: * The TCPT_PERSIST timer is used to keep window size information
59: * flowing even if the window goes shut. If all previous transmissions
60: * have been acknowledged (so that there are no retransmissions in progress),
61: * and the window is too small to bother sending anything, then we start
62: * the TCPT_PERSIST timer. When it expires, if the window is nonzero,
63: * we go to transmit state. Otherwise, at intervals send a single byte
64: * into the peer's window to force him to update our window information.
65: * We do this at most as often as TCPT_PERSMIN time intervals,
66: * but no more frequently than the current estimate of round-trip
67: * packet time. The TCPT_PERSIST timer is cleared whenever we receive
68: * a window update from the peer.
69: *
70: * The TCPT_KEEP timer is used to keep connections alive. If an
71: * connection is idle (no segments received) for TCPTV_KEEP_INIT amount of time,
72: * but not yet established, then we drop the connection. Once the connection
73: * is established, if the connection is idle for TCPTV_KEEP_IDLE time
74: * (and keepalives have been enabled on the socket), we begin to probe
75: * the connection. We force the peer to send us a segment by sending:
76: * <SEQ=SND.UNA-1><ACK=RCV.NXT><CTL=ACK>
77: * This segment is (deliberately) outside the window, and should elicit
78: * an ack segment in response from the peer. If, despite the TCPT_KEEP
79: * initiated segments we cannot elicit a response from a peer in TCPT_MAXIDLE
80: * amount of time probing, then we drop the connection.
81: */
82:
83: /*
84: * Time constants.
85: */
86: #define TCPTV_MSL ( 5*PR_SLOWHZ) /* max seg lifetime (hah!) */
87:
88: #define TCPTV_SRTTBASE 0 /* base roundtrip time;
89: if 0, no idea yet */
90: #define TCPTV_SRTTDFLT ( 3*PR_SLOWHZ) /* assumed RTT if no info */
91:
92: #define TCPTV_PERSMIN ( 5*PR_SLOWHZ) /* retransmit persistence */
93: #define TCPTV_PERSMAX ( 60*PR_SLOWHZ) /* maximum persist interval */
94:
95: #define TCPTV_KEEP_INIT ( 75*PR_SLOWHZ) /* initial connect keep alive */
96: #define TCPTV_KEEP_IDLE (120*60*PR_SLOWHZ) /* dflt time before probing */
97: #define TCPTV_KEEPINTVL ( 75*PR_SLOWHZ) /* default probe interval */
98: #define TCPTV_KEEPCNT 8 /* max probes before drop */
99:
100: #define TCPTV_MIN ( 1*PR_SLOWHZ) /* minimum allowable value */
101: /* #define TCPTV_REXMTMAX ( 64*PR_SLOWHZ) */ /* max allowable REXMT value */
102: #define TCPTV_REXMTMAX ( 12*PR_SLOWHZ) /* max allowable REXMT value */
103:
104: #define TCP_LINGERTIME 120 /* linger at most 2 minutes */
105:
106: #define TCP_MAXRXTSHIFT 12 /* maximum retransmits */
107:
108:
109: #ifdef TCPTIMERS
110: char *tcptimers[] =
111: { "REXMT", "PERSIST", "KEEP", "2MSL" };
112: #endif
113:
114: /*
115: * Force a time value to be in a certain range.
116: */
117: #define TCPT_RANGESET(tv, value, tvmin, tvmax) { \
118: (tv) = (value); \
119: if ((tv) < (tvmin)) \
120: (tv) = (tvmin); \
121: else if ((tv) > (tvmax)) \
122: (tv) = (tvmax); \
123: }
124:
1.1.1.2 root 125: extern const int tcp_backoff[];
1.1 root 126:
127: struct tcpcb;
128:
129: void tcp_fasttimo _P((void));
130: void tcp_slowtimo _P((void));
131: void tcp_canceltimers _P((struct tcpcb *));
132:
133: #endif
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