1 /*
2 * ppp-comp.h - Definitions for doing PPP packet compression.
3 *
4 * Copyright (c) 1994 The Australian National University.
5 * All rights reserved.
6 *
7 * Permission to use, copy, modify, and distribute this software and its
8 * documentation is hereby granted, provided that the above copyright
9 * notice appears in all copies. This software is provided without any
10 * warranty, express or implied. The Australian National University
11 * makes no representations about the suitability of this software for
12 * any purpose.
13 *
14 * IN NO EVENT SHALL THE AUSTRALIAN NATIONAL UNIVERSITY BE LIABLE TO ANY
15 * PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
16 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
17 * THE AUSTRALIAN NATIONAL UNIVERSITY HAVE BEEN ADVISED OF THE POSSIBILITY
18 * OF SUCH DAMAGE.
19 *
20 * THE AUSTRALIAN NATIONAL UNIVERSITY SPECIFICALLY DISCLAIMS ANY WARRANTIES,
21 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
22 * AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
23 * ON AN "AS IS" BASIS, AND THE AUSTRALIAN NATIONAL UNIVERSITY HAS NO
24 * OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS,
25 * OR MODIFICATIONS.
26 *
27 * $Id: ppp-comp.h,v 1.6 1997/11/27 06:04:44 paulus Exp $
28 */
29
30 /*
31 * ==FILEVERSION 980319==
32 *
33 * NOTE TO MAINTAINERS:
34 * If you modify this file at all, please set the above date.
35 * ppp-comp.h is shipped with a PPP distribution as well as with the kernel;
36 * if everyone increases the FILEVERSION number above, then scripts
37 * can do the right thing when deciding whether to install a new ppp-comp.h
38 * file. Don't change the format of that line otherwise, so the
39 * installation script can recognize it.
40 */
41
42 #ifndef _NET_PPP_COMP_H
43 #define _NET_PPP_COMP_H
44
45 /*
46 * The following symbols control whether we include code for
47 * various compression methods.
48 */
49
50 #ifndef DO_BSD_COMPRESS
51 #define DO_BSD_COMPRESS 1 /* by default, include BSD-Compress */
52 #endif
53 #ifndef DO_DEFLATE
54 #define DO_DEFLATE 1 /* by default, include Deflate */
55 #endif
56 #define DO_PREDICTOR_1 0
57 #define DO_PREDICTOR_2 0
58
59 /*
60 * Structure giving methods for compression/decompression.
61 */
62
63 struct compressor {
64 int compress_proto; /* CCP compression protocol number */
65
66 /* Allocate space for a compressor (transmit side) */
67 void *(*comp_alloc) (unsigned char *options, int opt_len);
68
69 /* Free space used by a compressor */
70 void (*comp_free) (void *state);
71
72 /* Initialize a compressor */
73 int (*comp_init) (void *state, unsigned char *options,
74 int opt_len, int unit, int opthdr, int debug);
75
76 /* Reset a compressor */
77 void (*comp_reset) (void *state);
78
79 /* Compress a packet */
80 int (*compress) (void *state, unsigned char *rptr,
81 unsigned char *obuf, int isize, int osize);
82
83 /* Return compression statistics */
84 void (*comp_stat) (void *state, struct compstat *stats);
85
86 /* Allocate space for a decompressor (receive side) */
87 void *(*decomp_alloc) (unsigned char *options, int opt_len);
88
89 /* Free space used by a decompressor */
90 void (*decomp_free) (void *state);
91
92 /* Initialize a decompressor */
93 int (*decomp_init) (void *state, unsigned char *options,
94 int opt_len, int unit, int opthdr, int mru,
95 int debug);
96
97 /* Reset a decompressor */
98 void (*decomp_reset) (void *state);
99
100 /* Decompress a packet. */
101 int (*decompress) (void *state, unsigned char *ibuf, int isize,
102 unsigned char *obuf, int osize);
103
104 /* Update state for an incompressible packet received */
105 void (*incomp) (void *state, unsigned char *ibuf, int icnt);
106
107 /* Return decompression statistics */
108 void (*decomp_stat) (void *state, struct compstat *stats);
109 };
110
111 /*
112 * The return value from decompress routine is the length of the
113 * decompressed packet if successful, otherwise DECOMP_ERROR
114 * or DECOMP_FATALERROR if an error occurred.
115 *
116 * We need to make this distinction so that we can disable certain
117 * useful functionality, namely sending a CCP reset-request as a result
118 * of an error detected after decompression. This is to avoid infringing
119 * a patent held by Motorola.
120 * Don't you just lurve software patents.
121 */
122
123 #define DECOMP_ERROR -1 /* error detected before decomp. */
124 #define DECOMP_FATALERROR -2 /* error detected after decomp. */
125
126 /*
127 * CCP codes.
128 */
129
130 #define CCP_CONFREQ 1
131 #define CCP_CONFACK 2
132 #define CCP_TERMREQ 5
133 #define CCP_TERMACK 6
134 #define CCP_RESETREQ 14
135 #define CCP_RESETACK 15
136
137 /*
138 * Max # bytes for a CCP option
139 */
140
141 #define CCP_MAX_OPTION_LENGTH 32
142
143 /*
144 * Parts of a CCP packet.
145 */
146
147 #define CCP_CODE(dp) ((dp)[0])
148 #define CCP_ID(dp) ((dp)[1])
149 #define CCP_LENGTH(dp) (((dp)[2] << 8) + (dp)[3])
150 #define CCP_HDRLEN 4
151
152 #define CCP_OPT_CODE(dp) ((dp)[0])
153 #define CCP_OPT_LENGTH(dp) ((dp)[1])
154 #define CCP_OPT_MINLEN 2
155
156 /*
157 * Definitions for BSD-Compress.
158 */
159
160 #define CI_BSD_COMPRESS 21 /* config. option for BSD-Compress */
161 #define CILEN_BSD_COMPRESS 3 /* length of config. option */
162
163 /* Macros for handling the 3rd byte of the BSD-Compress config option. */
164 #define BSD_NBITS(x) ((x) & 0x1F) /* number of bits requested */
165 #define BSD_VERSION(x) ((x) >> 5) /* version of option format */
166 #define BSD_CURRENT_VERSION 1 /* current version number */
167 #define BSD_MAKE_OPT(v, n) (((v) << 5) | (n))
168
169 #define BSD_MIN_BITS 9 /* smallest code size supported */
170 #define BSD_MAX_BITS 15 /* largest code size supported */
171
172 /*
173 * Definitions for Deflate.
174 */
175
176 #define CI_DEFLATE 26 /* config option for Deflate */
177 #define CI_DEFLATE_DRAFT 24 /* value used in original draft RFC */
178 #define CILEN_DEFLATE 4 /* length of its config option */
179
180 #define DEFLATE_MIN_SIZE 8
181 #define DEFLATE_MAX_SIZE 15
182 #define DEFLATE_METHOD_VAL 8
183 #define DEFLATE_SIZE(x) (((x) >> 4) + DEFLATE_MIN_SIZE)
184 #define DEFLATE_METHOD(x) ((x) & 0x0F)
185 #define DEFLATE_MAKE_OPT(w) ((((w) - DEFLATE_MIN_SIZE) << 4) \
186 + DEFLATE_METHOD_VAL)
187 #define DEFLATE_CHK_SEQUENCE 0
188
189 /*
190 * Definitions for other, as yet unsupported, compression methods.
191 */
192
193 #define CI_PREDICTOR_1 1 /* config option for Predictor-1 */
194 #define CILEN_PREDICTOR_1 2 /* length of its config option */
195 #define CI_PREDICTOR_2 2 /* config option for Predictor-2 */
196 #define CILEN_PREDICTOR_2 2 /* length of its config option */
197
198 #ifdef __KERNEL__
199 extern int ppp_register_compressor(struct compressor *);
200 extern void ppp_unregister_compressor(struct compressor *);
201 #endif /* __KERNEL__ */
202
203 #endif /* _NET_PPP_COMP_H */
204
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