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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: /* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
26: /*
27: * Copyright (c) 1989, 1993
28: * The Regents of the University of California. All rights reserved.
29: *
30: * Redistribution and use in source and binary forms, with or without
31: * modification, are permitted provided that the following conditions
32: * are met:
33: * 1. Redistributions of source code must retain the above copyright
34: * notice, this list of conditions and the following disclaimer.
35: * 2. Redistributions in binary form must reproduce the above copyright
36: * notice, this list of conditions and the following disclaimer in the
37: * documentation and/or other materials provided with the distribution.
38: * 3. All advertising materials mentioning features or use of this software
39: * must display the following acknowledgement:
40: * This product includes software developed by the University of
41: * California, Berkeley and its contributors.
42: * 4. Neither the name of the University nor the names of its contributors
43: * may be used to endorse or promote products derived from this software
44: * without specific prior written permission.
45: *
46: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
47: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
48: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
49: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
50: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
51: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
52: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
53: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
54: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
55: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
56: * SUCH DAMAGE.
57: *
58: * Van Jacobson ([email protected]), Dec 31, 1989:
59: * - Initial distribution.
60: */
61:
62: #define MAX_STATES 16 /* must be > 2 and < 256 */
63: #define MAX_HDR MLEN /* XXX 4bsd-ism: should really be 128 */
64:
65: /*
66: * Compressed packet format:
67: *
68: * The first octet contains the packet type (top 3 bits), TCP
69: * 'push' bit, and flags that indicate which of the 4 TCP sequence
70: * numbers have changed (bottom 5 bits). The next octet is a
71: * conversation number that associates a saved IP/TCP header with
72: * the compressed packet. The next two octets are the TCP checksum
73: * from the original datagram. The next 0 to 15 octets are
74: * sequence number changes, one change per bit set in the header
75: * (there may be no changes and there are two special cases where
76: * the receiver implicitly knows what changed -- see below).
77: *
78: * There are 5 numbers which can change (they are always inserted
79: * in the following order): TCP urgent pointer, window,
80: * acknowlegement, sequence number and IP ID. (The urgent pointer
81: * is different from the others in that its value is sent, not the
82: * change in value.) Since typical use of SLIP links is biased
83: * toward small packets (see comments on MTU/MSS below), changes
84: * use a variable length coding with one octet for numbers in the
85: * range 1 - 255 and 3 octets (0, MSB, LSB) for numbers in the
86: * range 256 - 65535 or 0. (If the change in sequence number or
87: * ack is more than 65535, an uncompressed packet is sent.)
88: */
89:
90: /*
91: * Packet types (must not conflict with IP protocol version)
92: *
93: * The top nibble of the first octet is the packet type. There are
94: * three possible types: IP (not proto TCP or tcp with one of the
95: * control flags set); uncompressed TCP (a normal IP/TCP packet but
96: * with the 8-bit protocol field replaced by an 8-bit connection id --
97: * this type of packet syncs the sender & receiver); and compressed
98: * TCP (described above).
99: *
100: * LSB of 4-bit field is TCP "PUSH" bit (a worthless anachronism) and
101: * is logically part of the 4-bit "changes" field that follows. Top
102: * three bits are actual packet type. For backward compatibility
103: * and in the interest of conserving bits, numbers are chosen so the
104: * IP protocol version number (4) which normally appears in this nibble
105: * means "IP packet".
106: */
107:
108: /* packet types */
109: #define TYPE_IP 0x40
110: #define TYPE_UNCOMPRESSED_TCP 0x70
111: #define TYPE_COMPRESSED_TCP 0x80
112: #define TYPE_ERROR 0x00
113:
114: /* Bits in first octet of compressed packet */
115: #define NEW_C 0x40 /* flag bits for what changed in a packet */
116: #define NEW_I 0x20
117: #define NEW_S 0x08
118: #define NEW_A 0x04
119: #define NEW_W 0x02
120: #define NEW_U 0x01
121:
122: /* reserved, special-case values of above */
123: #define SPECIAL_I (NEW_S|NEW_W|NEW_U) /* echoed interactive traffic */
124: #define SPECIAL_D (NEW_S|NEW_A|NEW_W|NEW_U) /* unidirectional data */
125: #define SPECIALS_MASK (NEW_S|NEW_A|NEW_W|NEW_U)
126:
127: #define TCP_PUSH_BIT 0x10
128:
129:
130: /*
131: * "state" data for each active tcp conversation on the wire. This is
132: * basically a copy of the entire IP/TCP header from the last packet
133: * we saw from the conversation together with a small identifier
134: * the transmit & receive ends of the line use to locate saved header.
135: */
136: struct cstate {
137: struct cstate *cs_next; /* next most recently used cstate (xmit only) */
138: u_short cs_hlen; /* size of hdr (receive only) */
139: u_char cs_id; /* connection # associated with this state */
140: u_char cs_filler;
141: union {
142: char csu_hdr[MAX_HDR];
143: struct ip csu_ip; /* ip/tcp hdr from most recent packet */
144: } slcs_u;
145: };
146: #define cs_ip slcs_u.csu_ip
147: #define cs_hdr slcs_u.csu_hdr
148:
149: /*
150: * all the state data for one serial line (we need one of these
151: * per line).
152: */
153: struct slcompress {
154: struct cstate *last_cs; /* most recently used tstate */
155: u_char last_recv; /* last rcvd conn. id */
156: u_char last_xmit; /* last sent conn. id */
157: u_short flags;
158: #ifndef SL_NO_STATS
159: int sls_packets; /* outbound packets */
160: int sls_compressed; /* outbound compressed packets */
161: int sls_searches; /* searches for connection state */
162: int sls_misses; /* times couldn't find conn. state */
163: int sls_uncompressedin; /* inbound uncompressed packets */
164: int sls_compressedin; /* inbound compressed packets */
165: int sls_errorin; /* inbound unknown type packets */
166: int sls_tossed; /* inbound packets tossed because of error */
167: #endif
168: struct cstate tstate[MAX_STATES]; /* xmit connection states */
169: struct cstate rstate[MAX_STATES]; /* receive connection states */
170: };
171: /* flag values */
172: #define SLF_TOSS 1 /* tossing rcvd frames because of input err */
173:
174: void sl_compress_init __P((struct slcompress *, int));
175: u_int sl_compress_tcp __P((struct mbuf *,
176: struct ip *, struct slcompress *, int));
177: int sl_uncompress_tcp __P((u_char **, int, u_int, struct slcompress *));
178: int sl_uncompress_tcp_part __P((u_char **, int, int, u_int,
179: struct slcompress *));
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