1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
|
/* $OpenBSD: tcp_timer.h,v 1.12 2008/11/08 12:54:58 dlg Exp $ */
/* $NetBSD: tcp_timer.h,v 1.6 1995/03/26 20:32:37 jtc Exp $ */
/*
* Copyright (c) 1982, 1986, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)tcp_timer.h 8.1 (Berkeley) 6/10/93
*/
#ifndef _NETINET_TCP_TIMER_H_
#define _NETINET_TCP_TIMER_H_
/*
* Definitions of the TCP timers. These timers are counted
* down PR_SLOWHZ times a second.
*/
#define TCPT_NTIMERS 4
#define TCPT_REXMT 0 /* retransmit */
#define TCPT_PERSIST 1 /* retransmit persistence */
#define TCPT_KEEP 2 /* keep alive */
#define TCPT_2MSL 3 /* 2*msl quiet time timer */
/*
* The TCPT_REXMT timer is used to force retransmissions.
* The TCP has the TCPT_REXMT timer set whenever segments
* have been sent for which ACKs are expected but not yet
* received. If an ACK is received which advances tp->snd_una,
* then the retransmit timer is cleared (if there are no more
* outstanding segments) or reset to the base value (if there
* are more ACKs expected). Whenever the retransmit timer goes off,
* we retransmit one unacknowledged segment, and do a backoff
* on the retransmit timer.
*
* The TCPT_PERSIST timer is used to keep window size information
* flowing even if the window goes shut. If all previous transmissions
* have been acknowledged (so that there are no retransmissions in progress),
* and the window is too small to bother sending anything, then we start
* the TCPT_PERSIST timer. When it expires, if the window is nonzero,
* we go to transmit state. Otherwise, at intervals send a single byte
* into the peer's window to force him to update our window information.
* We do this at most as often as TCPT_PERSMIN time intervals,
* but no more frequently than the current estimate of round-trip
* packet time. The TCPT_PERSIST timer is cleared whenever we receive
* a window update from the peer.
*
* The TCPT_KEEP timer is used to keep connections alive. If an
* connection is idle (no segments received) for TCPTV_KEEP_INIT amount of time,
* but not yet established, then we drop the connection. Once the connection
* is established, if the connection is idle for TCPTV_KEEP_IDLE time
* (and keepalives have been enabled on the socket), we begin to probe
* the connection. We force the peer to send us a segment by sending:
* <SEQ=SND.UNA-1><ACK=RCV.NXT><CTL=ACK>
* This segment is (deliberately) outside the window, and should elicit
* an ack segment in response from the peer. If, despite the TCPT_KEEP
* initiated segments we cannot elicit a response from a peer in TCPT_MAXIDLE
* amount of time probing, then we drop the connection.
*/
/*
* Time constants.
*/
#define TCPTV_MSL ( 30*PR_SLOWHZ) /* max seg lifetime (hah!) */
#define TCPTV_SRTTBASE 0 /* base roundtrip time;
if 0, no idea yet */
#define TCPTV_SRTTDFLT ( 3*PR_SLOWHZ) /* assumed RTT if no info */
#define TCPTV_PERSMIN ( 5*PR_SLOWHZ) /* retransmit persistence */
#define TCPTV_PERSMAX ( 60*PR_SLOWHZ) /* maximum persist interval */
#define TCPTV_KEEP_INIT ( 75*PR_SLOWHZ) /* initial connect keep alive */
#define TCPTV_KEEP_IDLE (120*60*PR_SLOWHZ) /* dflt time before probing */
#define TCPTV_KEEPINTVL ( 75*PR_SLOWHZ) /* default probe interval */
#define TCPTV_KEEPCNT 8 /* max probes before drop */
#define TCPTV_MIN ( 1*PR_SLOWHZ) /* minimum allowable value */
#define TCPTV_REXMTMAX ( 64*PR_SLOWHZ) /* max allowable REXMT value */
#define TCP_LINGERTIME 120 /* linger at most 2 minutes */
#define TCP_MAXRXTSHIFT 12 /* maximum retransmits */
#define TCP_DELACK_TICKS (hz / PR_FASTHZ) /* time to delay ACK */
#ifdef TCPTIMERS
const char *tcptimers[] =
{ "REXMT", "PERSIST", "KEEP", "2MSL" };
#endif /* TCPTIMERS */
/*
* Init, arm, disarm, and test TCP timers.
*/
#define TCP_TIMER_INIT(tp, timer) \
timeout_set(&(tp)->t_timer[(timer)], tcp_timer_funcs[(timer)], tp)
#define TCP_TIMER_ARM(tp, timer, nticks) \
timeout_add(&(tp)->t_timer[(timer)], (nticks) * (hz / PR_SLOWHZ))
#define TCP_TIMER_DISARM(tp, timer) \
timeout_del(&(tp)->t_timer[(timer)])
#define TCP_TIMER_ISARMED(tp, timer) \
timeout_pending(&(tp)->t_timer[(timer)])
/*
* Force a time value to be in a certain range.
*/
#define TCPT_RANGESET(tv, value, tvmin, tvmax) \
do { \
(tv) = (value); \
if ((tv) < (tvmin)) \
(tv) = (tvmin); \
else if ((tv) > (tvmax)) \
(tv) = (tvmax); \
} while (/* CONSTCOND */ 0)
#ifdef _KERNEL
typedef void (*tcp_timer_func_t)(void *);
extern const tcp_timer_func_t tcp_timer_funcs[TCPT_NTIMERS];
extern int tcptv_keep_init;
extern int tcp_keepidle; /* time before keepalive probes begin */
extern int tcp_keepintvl; /* time between keepalive probes */
extern int tcp_maxidle; /* time to drop after starting probes */
extern int tcp_ttl; /* time to live for TCP segs */
extern int tcp_backoff[];
void tcp_timer_init(void);
#endif /* _KERNEL */
#endif /* _NETINET_TCP_TIMER_H_ */
|
