root / slirp / tcp_timer.h @ d64477af
History | View | Annotate | Download (6 kB)
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 |
|
129 |
extern int tcp_keepidle; /* time before keepalive probes begin */ |
130 |
extern int tcp_keepintvl; /* time between keepalive probes */ |
131 |
extern int tcp_maxidle; /* time to drop after starting probes */ |
132 |
extern int tcp_ttl; /* time to live for TCP segs */ |
133 |
extern int tcp_backoff[]; |
134 |
|
135 |
struct tcpcb;
|
136 |
|
137 |
void tcp_fasttimo _P((void)); |
138 |
void tcp_slowtimo _P((void)); |
139 |
void tcp_canceltimers _P((struct tcpcb *)); |
140 |
struct tcpcb * tcp_timers _P((register struct tcpcb *, int)); |
141 |
|
142 |
#endif
|