include/linux/ppp-comp.h

   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         /* Extra skb space needed by the compressor algorithm */
 115         unsigned int comp_extra;
 116 };
 117
 118 /*
 119  * The return value from decompress routine is the length of the
 120  * decompressed packet if successful, otherwise DECOMP_ERROR
 121  * or DECOMP_FATALERROR if an error occurred.
 122  *
 123  * We need to make this distinction so that we can disable certain
 124  * useful functionality, namely sending a CCP reset-request as a result
 125  * of an error detected after decompression.  This is to avoid infringing
 126  * a patent held by Motorola.
 127  * Don't you just lurve software patents.
 128  */
 129
 130 #define DECOMP_ERROR            -1      /* error detected before decomp. */
 131 #define DECOMP_FATALERROR       -2      /* error detected after decomp. */
 132
 133 /*
 134  * CCP codes.
 135  */
 136
 137 #define CCP_CONFREQ     1
 138 #define CCP_CONFACK     2
 139 #define CCP_TERMREQ     5
 140 #define CCP_TERMACK     6
 141 #define CCP_RESETREQ    14
 142 #define CCP_RESETACK    15
 143
 144 /*
 145  * Max # bytes for a CCP option
 146  */
 147
 148 #define CCP_MAX_OPTION_LENGTH   32
 149
 150 /*
 151  * Parts of a CCP packet.
 152  */
 153
 154 #define CCP_CODE(dp)            ((dp)[0])
 155 #define CCP_ID(dp)              ((dp)[1])
 156 #define CCP_LENGTH(dp)          (((dp)[2] << 8) + (dp)[3])
 157 #define CCP_HDRLEN              4
 158
 159 #define CCP_OPT_CODE(dp)        ((dp)[0])
 160 #define CCP_OPT_LENGTH(dp)      ((dp)[1])
 161 #define CCP_OPT_MINLEN          2
 162
 163 /*
 164  * Definitions for BSD-Compress.
 165  */
 166
 167 #define CI_BSD_COMPRESS         21      /* config. option for BSD-Compress */
 168 #define CILEN_BSD_COMPRESS      3       /* length of config. option */
 169
 170 /* Macros for handling the 3rd byte of the BSD-Compress config option. */
 171 #define BSD_NBITS(x)            ((x) & 0x1F)    /* number of bits requested */
 172 #define BSD_VERSION(x)          ((x) >> 5)      /* version of option format */
 173 #define BSD_CURRENT_VERSION     1               /* current version number */
 174 #define BSD_MAKE_OPT(v, n)      (((v) << 5) | (n))
 175
 176 #define BSD_MIN_BITS            9       /* smallest code size supported */
 177 #define BSD_MAX_BITS            15      /* largest code size supported */
 178
 179 /*
 180  * Definitions for Deflate.
 181  */
 182
 183 #define CI_DEFLATE              26      /* config option for Deflate */
 184 #define CI_DEFLATE_DRAFT        24      /* value used in original draft RFC */
 185 #define CILEN_DEFLATE           4       /* length of its config option */
 186
 187 #define DEFLATE_MIN_SIZE        9
 188 #define DEFLATE_MAX_SIZE        15
 189 #define DEFLATE_METHOD_VAL      8
 190 #define DEFLATE_SIZE(x)         (((x) >> 4) + 8)
 191 #define DEFLATE_METHOD(x)       ((x) & 0x0F)
 192 #define DEFLATE_MAKE_OPT(w)     ((((w) - 8) << 4) + DEFLATE_METHOD_VAL)
 193 #define DEFLATE_CHK_SEQUENCE    0
 194
 195 /*
 196  * Definitions for MPPE.
 197  */
 198
 199 #define CI_MPPE                18      /* config option for MPPE */
 200 #define CILEN_MPPE              6      /* length of config option */
 201
 202 /*
 203  * Definitions for other, as yet unsupported, compression methods.
 204  */
 205
 206 #define CI_PREDICTOR_1          1       /* config option for Predictor-1 */
 207 #define CILEN_PREDICTOR_1       2       /* length of its config option */
 208 #define CI_PREDICTOR_2          2       /* config option for Predictor-2 */
 209 #define CILEN_PREDICTOR_2       2       /* length of its config option */
 210
 211
 212 #endif /* _NET_PPP_COMP_H */