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 struct module;
46
47 /*
48 * The following symbols control whether we include code for
49 * various compression methods.
50 */
51
52 #ifndef DO_BSD_COMPRESS
53 #define DO_BSD_COMPRESS 1 /* by default, include BSD-Compress */
54 #endif
55 #ifndef DO_DEFLATE
56 #define DO_DEFLATE 1 /* by default, include Deflate */
57 #endif
58 #define DO_PREDICTOR_1 0
59 #define DO_PREDICTOR_2 0
60
61 /*
62 * Structure giving methods for compression/decompression.
63 */
64
65 struct compressor {
66 int compress_proto; /* CCP compression protocol number */
67
68 /* Allocate space for a compressor (transmit side) */
69 void *(*comp_alloc) (unsigned char *options, int opt_len);
70
71 /* Free space used by a compressor */
72 void (*comp_free) (void *state);
73
74 /* Initialize a compressor */
75 int (*comp_init) (void *state, unsigned char *options,
76 int opt_len, int unit, int opthdr, int debug);
77
78 /* Reset a compressor */
79 void (*comp_reset) (void *state);
80
81 /* Compress a packet */
82 int (*compress) (void *state, unsigned char *rptr,
83 unsigned char *obuf, int isize, int osize);
84
85 /* Return compression statistics */
86 void (*comp_stat) (void *state, struct compstat *stats);
87
88 /* Allocate space for a decompressor (receive side) */
89 void *(*decomp_alloc) (unsigned char *options, int opt_len);
90
91 /* Free space used by a decompressor */
92 void (*decomp_free) (void *state);
93
94 /* Initialize a decompressor */
95 int (*decomp_init) (void *state, unsigned char *options,
96 int opt_len, int unit, int opthdr, int mru,
97 int debug);
98
99 /* Reset a decompressor */
100 void (*decomp_reset) (void *state);
101
102 /* Decompress a packet. */
103 int (*decompress) (void *state, unsigned char *ibuf, int isize,
104 unsigned char *obuf, int osize);
105
106 /* Update state for an incompressible packet received */
107 void (*incomp) (void *state, unsigned char *ibuf, int icnt);
108
109 /* Return decompression statistics */
110 void (*decomp_stat) (void *state, struct compstat *stats);
111
112 /* Used in locking compressor modules */
113 struct module *owner;
114 };
115
116 /*
117 * The return value from decompress routine is the length of the
118 * decompressed packet if successful, otherwise DECOMP_ERROR
119 * or DECOMP_FATALERROR if an error occurred.
120 *
121 * We need to make this distinction so that we can disable certain
122 * useful functionality, namely sending a CCP reset-request as a result
123 * of an error detected after decompression. This is to avoid infringing
124 * a patent held by Motorola.
125 * Don't you just lurve software patents.
126 */
127
128 #define DECOMP_ERROR -1 /* error detected before decomp. */
129 #define DECOMP_FATALERROR -2 /* error detected after decomp. */
130
131 /*
132 * CCP codes.
133 */
134
135 #define CCP_CONFREQ 1
136 #define CCP_CONFACK 2
137 #define CCP_TERMREQ 5
138 #define CCP_TERMACK 6
139 #define CCP_RESETREQ 14
140 #define CCP_RESETACK 15
141
142 /*
143 * Max # bytes for a CCP option
144 */
145
146 #define CCP_MAX_OPTION_LENGTH 32
147
148 /*
149 * Parts of a CCP packet.
150 */
151
152 #define CCP_CODE(dp) ((dp)[0])
153 #define CCP_ID(dp) ((dp)[1])
154 #define CCP_LENGTH(dp) (((dp)[2] << 8) + (dp)[3])
155 #define CCP_HDRLEN 4
156
157 #define CCP_OPT_CODE(dp) ((dp)[0])
158 #define CCP_OPT_LENGTH(dp) ((dp)[1])
159 #define CCP_OPT_MINLEN 2
160
161 /*
162 * Definitions for BSD-Compress.
163 */
164
165 #define CI_BSD_COMPRESS 21 /* config. option for BSD-Compress */
166 #define CILEN_BSD_COMPRESS 3 /* length of config. option */
167
168 /* Macros for handling the 3rd byte of the BSD-Compress config option. */
169 #define BSD_NBITS(x) ((x) & 0x1F) /* number of bits requested */
170 #define BSD_VERSION(x) ((x) >> 5) /* version of option format */
171 #define BSD_CURRENT_VERSION 1 /* current version number */
172 #define BSD_MAKE_OPT(v, n) (((v) << 5) | (n))
173
174 #define BSD_MIN_BITS 9 /* smallest code size supported */
175 #define BSD_MAX_BITS 15 /* largest code size supported */
176
177 /*
178 * Definitions for Deflate.
179 */
180
181 #define CI_DEFLATE 26 /* config option for Deflate */
182 #define CI_DEFLATE_DRAFT 24 /* value used in original draft RFC */
183 #define CILEN_DEFLATE 4 /* length of its config option */
184
185 #define DEFLATE_MIN_SIZE 9
186 #define DEFLATE_MAX_SIZE 15
187 #define DEFLATE_METHOD_VAL 8
188 #define DEFLATE_SIZE(x) (((x) >> 4) + 8)
189 #define DEFLATE_METHOD(x) ((x) & 0x0F)
190 #define DEFLATE_MAKE_OPT(w) ((((w) - 8) << 4) + DEFLATE_METHOD_VAL)
191 #define DEFLATE_CHK_SEQUENCE 0
192
193 /*
194 * Definitions for other, as yet unsupported, compression methods.
195 */
196
197 #define CI_PREDICTOR_1 1 /* config option for Predictor-1 */
198 #define CILEN_PREDICTOR_1 2 /* length of its config option */
199 #define CI_PREDICTOR_2 2 /* config option for Predictor-2 */
200 #define CILEN_PREDICTOR_2 2 /* length of its config option */
201
202 #ifdef __KERNEL__
203 extern int ppp_register_compressor(struct compressor *);
204 extern void ppp_unregister_compressor(struct compressor *);
205 #endif /* __KERNEL__ */
206
207 #endif /* _NET_PPP_COMP_H */
208
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