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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: * Definitions for tcp compression routines.
24: *
25: * Copyright (c) 1989, 1993
26: * The Regents of the University of California. All rights reserved.
27: *
28: * Redistribution and use in source and binary forms, with or without
29: * modification, are permitted provided that the following conditions
30: * are met:
31: * 1. Redistributions of source code must retain the above copyright
32: * notice, this list of conditions and the following disclaimer.
33: * 2. Redistributions in binary form must reproduce the above copyright
34: * notice, this list of conditions and the following disclaimer in the
35: * documentation and/or other materials provided with the distribution.
36: * 3. All advertising materials mentioning features or use of this software
37: * must display the following acknowledgement:
38: * This product includes software developed by the University of
39: * California, Berkeley and its contributors.
40: * 4. Neither the name of the University nor the names of its contributors
41: * may be used to endorse or promote products derived from this software
42: * without specific prior written permission.
43: *
44: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
45: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
46: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
47: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
48: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
49: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
50: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
51: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
52: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
53: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
54: * SUCH DAMAGE.
55: *
56: * Van Jacobson ([email protected]), Dec 31, 1989:
57: * - Initial distribution.
58: */
59:
60: #ifndef _NET_SLCOMPRESS_H_
61: #define _NET_SLCOMPRESS_H_
62:
63: #include <netinet/ip.h>
64:
65: #define MAX_STATES 16 /* must be > 2 and < 256 */
66: #define MAX_HDR MLEN /* XXX 4bsd-ism: should really be 128 */
67:
68: /*
69: * Compressed packet format:
70: *
71: * The first octet contains the packet type (top 3 bits), TCP
72: * 'push' bit, and flags that indicate which of the 4 TCP sequence
73: * numbers have changed (bottom 5 bits). The next octet is a
74: * conversation number that associates a saved IP/TCP header with
75: * the compressed packet. The next two octets are the TCP checksum
76: * from the original datagram. The next 0 to 15 octets are
77: * sequence number changes, one change per bit set in the header
78: * (there may be no changes and there are two special cases where
79: * the receiver implicitly knows what changed -- see below).
80: *
81: * There are 5 numbers which can change (they are always inserted
82: * in the following order): TCP urgent pointer, window,
83: * acknowledgement, sequence number and IP ID. (The urgent pointer
84: * is different from the others in that its value is sent, not the
85: * change in value.) Since typical use of SLIP links is biased
86: * toward small packets (see comments on MTU/MSS below), changes
87: * use a variable length coding with one octet for numbers in the
88: * range 1 - 255 and 3 octets (0, MSB, LSB) for numbers in the
89: * range 256 - 65535 or 0. (If the change in sequence number or
90: * ack is more than 65535, an uncompressed packet is sent.)
91: */
92:
93: /*
94: * Packet types (must not conflict with IP protocol version)
95: *
96: * The top nibble of the first octet is the packet type. There are
97: * three possible types: IP (not proto TCP or tcp with one of the
98: * control flags set); uncompressed TCP (a normal IP/TCP packet but
99: * with the 8-bit protocol field replaced by an 8-bit connection id --
100: * this type of packet syncs the sender & receiver); and compressed
101: * TCP (described above).
102: *
103: * LSB of 4-bit field is TCP "PUSH" bit (a worthless anachronism) and
104: * is logically part of the 4-bit "changes" field that follows. Top
105: * three bits are actual packet type. For backward compatibility
106: * and in the interest of conserving bits, numbers are chosen so the
107: * IP protocol version number (4) which normally appears in this nibble
108: * means "IP packet".
109: */
110:
111: /* packet types */
112: #define TYPE_IP 0x40
113: #define TYPE_UNCOMPRESSED_TCP 0x70
114: #define TYPE_COMPRESSED_TCP 0x80
115: #define TYPE_ERROR 0x00
116:
117: /* Bits in first octet of compressed packet */
118: #define NEW_C 0x40 /* flag bits for what changed in a packet */
119: #define NEW_I 0x20
120: #define NEW_S 0x08
121: #define NEW_A 0x04
122: #define NEW_W 0x02
123: #define NEW_U 0x01
124:
125: /* reserved, special-case values of above */
126: #define SPECIAL_I (NEW_S|NEW_W|NEW_U) /* echoed interactive traffic */
127: #define SPECIAL_D (NEW_S|NEW_A|NEW_W|NEW_U) /* unidirectional data */
128: #define SPECIALS_MASK (NEW_S|NEW_A|NEW_W|NEW_U)
129:
130: #define TCP_PUSH_BIT 0x10
131:
132:
133: /*
134: * "state" data for each active tcp conversation on the wire. This is
135: * basically a copy of the entire IP/TCP header from the last packet
136: * we saw from the conversation together with a small identifier
137: * the transmit & receive ends of the line use to locate saved header.
138: */
139: struct cstate {
140: struct cstate *cs_next; /* next most recently used cstate (xmit only) */
141: u_int16_t cs_hlen; /* size of hdr (receive only) */
142: u_char cs_id; /* connection # associated with this state */
143: u_char cs_filler;
144: union {
145: char csu_hdr[MAX_HDR];
146: struct ip csu_ip; /* ip/tcp hdr from most recent packet */
147: } slcs_u;
148: };
149: #define cs_ip slcs_u.csu_ip
150: #define cs_hdr slcs_u.csu_hdr
151:
152: /*
153: * all the state data for one serial line (we need one of these
154: * per line).
155: */
156: struct slcompress {
157: struct cstate *last_cs; /* most recently used tstate */
158: u_char last_recv; /* last rcvd conn. id */
159: u_char last_xmit; /* last sent conn. id */
160: u_int16_t flags;
161: #ifndef SL_NO_STATS
162: int sls_packets; /* outbound packets */
163: int sls_compressed; /* outbound compressed packets */
164: int sls_searches; /* searches for connection state */
165: int sls_misses; /* times couldn't find conn. state */
166: int sls_uncompressedin; /* inbound uncompressed packets */
167: int sls_compressedin; /* inbound compressed packets */
168: int sls_errorin; /* inbound unknown type packets */
169: int sls_tossed; /* inbound packets tossed because of error */
170: #endif
171: struct cstate tstate[MAX_STATES]; /* xmit connection states */
172: struct cstate rstate[MAX_STATES]; /* receive connection states */
173: };
174: /* flag values */
175: #define SLF_TOSS 1 /* tossing rcvd frames because of input err */
176:
177: void sl_compress_init __P((struct slcompress *, int));
178: u_int sl_compress_tcp __P((struct mbuf *,
179: struct ip *, struct slcompress *, int));
180: int sl_uncompress_tcp __P((u_char **, int, u_int, struct slcompress *));
181: int sl_uncompress_tcp_core __P((u_char *, int, int, u_int,
182: struct slcompress *, u_char **, u_int *));
183:
184: #endif /* !_NET_SLCOMPRESS_H_ */
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