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1.1 root 1: /*
2: * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
3: *
4: * @APPLE_LICENSE_HEADER_START@
5: *
6: * Portions Copyright (c) 1999 Apple Computer, Inc. All Rights
7: * Reserved. This file contains Original Code and/or Modifications of
8: * Original Code as defined in and that are subject to the Apple Public
9: * Source License Version 1.1 (the "License"). You may not use this file
10: * except in compliance with the License. Please obtain a copy of the
11: * License at http://www.apple.com/publicsource and read it before using
12: * this file.
13: *
14: * The Original Code and all software distributed under the License are
15: * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
16: * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
17: * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
18: * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the
19: * License for the specific language governing rights and limitations
20: * under the License.
21: *
22: * @APPLE_LICENSE_HEADER_END@
23: */
24:
25: /*
26: * Copyright (c) 1982, 1986, 1988, 1993
27: * The Regents of the University of California. All rights reserved.
28: *
29: * Redistribution and use in source and binary forms, with or without
30: * modification, are permitted provided that the following conditions
31: * are met:
32: * 1. Redistributions of source code must retain the above copyright
33: * notice, this list of conditions and the following disclaimer.
34: * 2. Redistributions in binary form must reproduce the above copyright
35: * notice, this list of conditions and the following disclaimer in the
36: * documentation and/or other materials provided with the distribution.
37: * 3. All advertising materials mentioning features or use of this software
38: * must display the following acknowledgement:
39: * This product includes software developed by the University of
40: * California, Berkeley and its contributors.
41: * 4. Neither the name of the University nor the names of its contributors
42: * may be used to endorse or promote products derived from this software
43: * without specific prior written permission.
44: *
45: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
46: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
47: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
48: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
49: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
50: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
51: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
52: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
53: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
54: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
55: * SUCH DAMAGE.
56: *
57: * @(#)spp_timer.h 8.1 (Berkeley) 6/10/93
58: */
59:
60: /*
61: * Definitions of the SPP timers. These timers are counted
62: * down PR_SLOWHZ times a second.
63: */
64: #define SPPT_NTIMERS 4
65:
66: #define SPPT_REXMT 0 /* retransmit */
67: #define SPPT_PERSIST 1 /* retransmit persistance */
68: #define SPPT_KEEP 2 /* keep alive */
69: #define SPPT_2MSL 3 /* 2*msl quiet time timer */
70:
71: /*
72: * The SPPT_REXMT timer is used to force retransmissions.
73: * The SPP has the SPPT_REXMT timer set whenever segments
74: * have been sent for which ACKs are expected but not yet
75: * received. If an ACK is received which advances tp->snd_una,
76: * then the retransmit timer is cleared (if there are no more
77: * outstanding segments) or reset to the base value (if there
78: * are more ACKs expected). Whenever the retransmit timer goes off,
79: * we retransmit one unacknowledged segment, and do a backoff
80: * on the retransmit timer.
81: *
82: * The SPPT_PERSIST timer is used to keep window size information
83: * flowing even if the window goes shut. If all previous transmissions
84: * have been acknowledged (so that there are no retransmissions in progress),
85: * and the window is too small to bother sending anything, then we start
86: * the SPPT_PERSIST timer. When it expires, if the window is nonzero,
87: * we go to transmit state. Otherwise, at intervals send a single byte
88: * into the peer's window to force him to update our window information.
89: * We do this at most as often as SPPT_PERSMIN time intervals,
90: * but no more frequently than the current estimate of round-trip
91: * packet time. The SPPT_PERSIST timer is cleared whenever we receive
92: * a window update from the peer.
93: *
94: * The SPPT_KEEP timer is used to keep connections alive. If an
95: * connection is idle (no segments received) for SPPTV_KEEP amount of time,
96: * but not yet established, then we drop the connection. If the connection
97: * is established, then we force the peer to send us a segment by sending:
98: * <SEQ=SND.UNA-1><ACK=RCV.NXT><CTL=ACK>
99: * This segment is (deliberately) outside the window, and should elicit
100: * an ack segment in response from the peer. If, despite the SPPT_KEEP
101: * initiated segments we cannot elicit a response from a peer in SPPT_MAXIDLE
102: * amount of time, then we drop the connection.
103: */
104:
105: #define SPP_TTL 30 /* default time to live for SPP segs */
106: /*
107: * Time constants.
108: */
109: #define SPPTV_MSL ( 15*PR_SLOWHZ) /* max seg lifetime */
110: #define SPPTV_SRTTBASE 0 /* base roundtrip time;
111: if 0, no idea yet */
112: #define SPPTV_SRTTDFLT ( 3*PR_SLOWHZ) /* assumed RTT if no info */
113:
114: #define SPPTV_PERSMIN ( 5*PR_SLOWHZ) /* retransmit persistance */
115: #define SPPTV_PERSMAX ( 60*PR_SLOWHZ) /* maximum persist interval */
116:
117: #define SPPTV_KEEP ( 75*PR_SLOWHZ) /* keep alive - 75 secs */
118: #define SPPTV_MAXIDLE ( 8*SPPTV_KEEP) /* maximum allowable idle
119: time before drop conn */
120:
121: #define SPPTV_MIN ( 1*PR_SLOWHZ) /* minimum allowable value */
122: #define SPPTV_REXMTMAX ( 64*PR_SLOWHZ) /* max allowable REXMT value */
123:
124: #define SPP_LINGERTIME 120 /* linger at most 2 minutes */
125:
126: #define SPP_MAXRXTSHIFT 12 /* maximum retransmits */
127:
128: #ifdef SPPTIMERS
129: char *spptimers[] =
130: { "REXMT", "PERSIST", "KEEP", "2MSL" };
131: #endif
132:
133: /*
134: * Force a time value to be in a certain range.
135: */
136: #define SPPT_RANGESET(tv, value, tvmin, tvmax) { \
137: (tv) = (value); \
138: if ((tv) < (tvmin)) \
139: (tv) = (tvmin); \
140: else if ((tv) > (tvmax)) \
141: (tv) = (tvmax); \
142: }
143:
144: #ifdef KERNEL
145: extern int spp_backoff[];
146: #endif
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