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001: /*
002:  * ppp-comp.h - Definitions for doing PPP packet compression.
003:  *
004:  * Copyright (c) 1994 The Australian National University.
005:  * All rights reserved.
006:  *
007:  * Permission to use, copy, modify, and distribute this software and its
008:  * documentation is hereby granted, provided that the above copyright
009:  * notice appears in all copies.  This software is provided without any
010:  * warranty, express or implied. The Australian National University
011:  * makes no representations about the suitability of this software for
012:  * any purpose.
013:  *
014:  * IN NO EVENT SHALL THE AUSTRALIAN NATIONAL UNIVERSITY BE LIABLE TO ANY
015:  * PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
016:  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
017:  * THE AUSTRALIAN NATIONAL UNIVERSITY HAVE BEEN ADVISED OF THE POSSIBILITY
018:  * OF SUCH DAMAGE.
019:  *
020:  * THE AUSTRALIAN NATIONAL UNIVERSITY SPECIFICALLY DISCLAIMS ANY WARRANTIES,
021:  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
022:  * AND FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
023:  * ON AN "AS IS" BASIS, AND THE AUSTRALIAN NATIONAL UNIVERSITY HAS NO
024:  * OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS,
025:  * OR MODIFICATIONS.
026:  */
027: 
028: /*
029:  *  ==FILEVERSION 980319==
030:  *
031:  *  NOTE TO MAINTAINERS:
032:  *     If you modify this file at all, please set the above date.
033:  *     ppp-comp.h is shipped with a PPP distribution as well as with the kernel;
034:  *     if everyone increases the FILEVERSION number above, then scripts
035:  *     can do the right thing when deciding whether to install a new ppp-comp.h
036:  *     file.  Don't change the format of that line otherwise, so the
037:  *     installation script can recognize it.
038:  */
039: 
040: #ifndef _NET_PPP_COMP_H
041: #define _NET_PPP_COMP_H
042: 
043: struct module;
044: 
045: /*
046:  * The following symbols control whether we include code for
047:  * various compression methods.
048:  */
049: 
050: #ifndef DO_BSD_COMPRESS
051: #define DO_BSD_COMPRESS 1       /* by default, include BSD-Compress */
052: #endif
053: #ifndef DO_DEFLATE
054: #define DO_DEFLATE      1       /* by default, include Deflate */
055: #endif
056: #define DO_PREDICTOR_1  0
057: #define DO_PREDICTOR_2  0
058: 
059: /*
060:  * Structure giving methods for compression/decompression.
061:  */
062: 
063: struct compressor {
064:         int     compress_proto; /* CCP compression protocol number */
065: 
066:         /* Allocate space for a compressor (transmit side) */
067:         void    *(*comp_alloc) (unsigned char *options, int opt_len);
068: 
069:         /* Free space used by a compressor */
070:         void    (*comp_free) (void *state);
071: 
072:         /* Initialize a compressor */
073:         int     (*comp_init) (void *state, unsigned char *options,
074:                               int opt_len, int unit, int opthdr, int debug);
075: 
076:         /* Reset a compressor */
077:         void    (*comp_reset) (void *state);
078: 
079:         /* Compress a packet */
080:         int     (*compress) (void *state, unsigned char *rptr,
081:                               unsigned char *obuf, int isize, int osize);
082: 
083:         /* Return compression statistics */
084:         void    (*comp_stat) (void *state, struct compstat *stats);
085: 
086:         /* Allocate space for a decompressor (receive side) */
087:         void    *(*decomp_alloc) (unsigned char *options, int opt_len);
088: 
089:         /* Free space used by a decompressor */
090:         void    (*decomp_free) (void *state);
091: 
092:         /* Initialize a decompressor */
093:         int     (*decomp_init) (void *state, unsigned char *options,
094:                                 int opt_len, int unit, int opthdr, int mru,
095:                                 int debug);
096: 
097:         /* Reset a decompressor */
098:         void    (*decomp_reset) (void *state);
099: 
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:         /* Used in locking compressor modules */
111:         struct module *owner;
112:         /* Extra skb space needed by the compressor algorithm */
113:         unsigned int comp_extra;
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 MPPE.
195:  */
196: 
197: #define CI_MPPE                18      /* config option for MPPE */
198: #define CILEN_MPPE              6      /* length of config option */
199: 
200: /*
201:  * Definitions for other, as yet unsupported, compression methods.
202:  */
203: 
204: #define CI_PREDICTOR_1          1       /* config option for Predictor-1 */
205: #define CILEN_PREDICTOR_1       2       /* length of its config option */
206: #define CI_PREDICTOR_2          2       /* config option for Predictor-2 */
207: #define CILEN_PREDICTOR_2       2       /* length of its config option */
208: 
209: 
210: #endif /* _NET_PPP_COMP_H */
211: 

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