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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, 1988, 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: * @(#)spp_timer.h 8.1 (Berkeley) 6/10/93
55: */
56:
57: /*
58: * Definitions of the SPP timers. These timers are counted
59: * down PR_SLOWHZ times a second.
60: */
61: #define SPPT_NTIMERS 4
62:
63: #define SPPT_REXMT 0 /* retransmit */
64: #define SPPT_PERSIST 1 /* retransmit persistance */
65: #define SPPT_KEEP 2 /* keep alive */
66: #define SPPT_2MSL 3 /* 2*msl quiet time timer */
67:
68: /*
69: * The SPPT_REXMT timer is used to force retransmissions.
70: * The SPP has the SPPT_REXMT timer set whenever segments
71: * have been sent for which ACKs are expected but not yet
72: * received. If an ACK is received which advances tp->snd_una,
73: * then the retransmit timer is cleared (if there are no more
74: * outstanding segments) or reset to the base value (if there
75: * are more ACKs expected). Whenever the retransmit timer goes off,
76: * we retransmit one unacknowledged segment, and do a backoff
77: * on the retransmit timer.
78: *
79: * The SPPT_PERSIST timer is used to keep window size information
80: * flowing even if the window goes shut. If all previous transmissions
81: * have been acknowledged (so that there are no retransmissions in progress),
82: * and the window is too small to bother sending anything, then we start
83: * the SPPT_PERSIST timer. When it expires, if the window is nonzero,
84: * we go to transmit state. Otherwise, at intervals send a single byte
85: * into the peer's window to force him to update our window information.
86: * We do this at most as often as SPPT_PERSMIN time intervals,
87: * but no more frequently than the current estimate of round-trip
88: * packet time. The SPPT_PERSIST timer is cleared whenever we receive
89: * a window update from the peer.
90: *
91: * The SPPT_KEEP timer is used to keep connections alive. If an
92: * connection is idle (no segments received) for SPPTV_KEEP amount of time,
93: * but not yet established, then we drop the connection. If the connection
94: * is established, then we force the peer to send us a segment by sending:
95: * <SEQ=SND.UNA-1><ACK=RCV.NXT><CTL=ACK>
96: * This segment is (deliberately) outside the window, and should elicit
97: * an ack segment in response from the peer. If, despite the SPPT_KEEP
98: * initiated segments we cannot elicit a response from a peer in SPPT_MAXIDLE
99: * amount of time, then we drop the connection.
100: */
101:
102: #define SPP_TTL 30 /* default time to live for SPP segs */
103: /*
104: * Time constants.
105: */
106: #define SPPTV_MSL ( 15*PR_SLOWHZ) /* max seg lifetime */
107: #define SPPTV_SRTTBASE 0 /* base roundtrip time;
108: if 0, no idea yet */
109: #define SPPTV_SRTTDFLT ( 3*PR_SLOWHZ) /* assumed RTT if no info */
110:
111: #define SPPTV_PERSMIN ( 5*PR_SLOWHZ) /* retransmit persistance */
112: #define SPPTV_PERSMAX ( 60*PR_SLOWHZ) /* maximum persist interval */
113:
114: #define SPPTV_KEEP ( 75*PR_SLOWHZ) /* keep alive - 75 secs */
115: #define SPPTV_MAXIDLE ( 8*SPPTV_KEEP) /* maximum allowable idle
116: time before drop conn */
117:
118: #define SPPTV_MIN ( 1*PR_SLOWHZ) /* minimum allowable value */
119: #define SPPTV_REXMTMAX ( 64*PR_SLOWHZ) /* max allowable REXMT value */
120:
121: #define SPP_LINGERTIME 120 /* linger at most 2 minutes */
122:
123: #define SPP_MAXRXTSHIFT 12 /* maximum retransmits */
124:
125: #ifdef SPPTIMERS
126: char *spptimers[] =
127: { "REXMT", "PERSIST", "KEEP", "2MSL" };
128: #endif
129:
130: /*
131: * Force a time value to be in a certain range.
132: */
133: #define SPPT_RANGESET(tv, value, tvmin, tvmax) { \
134: (tv) = (value); \
135: if ((tv) < (tvmin)) \
136: (tv) = (tvmin); \
137: else if ((tv) > (tvmax)) \
138: (tv) = (tvmax); \
139: }
140:
141: #ifdef KERNEL
142: extern int spp_backoff[];
143: #endif
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