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
  28 /*
  29  *  ==FILEVERSION 980319==
  30  *
  31  *  NOTE TO MAINTAINERS:
  32  *     If you modify this file at all, please set the above date.
  33  *     ppp-comp.h is shipped with a PPP distribution as well as with the kernel;
  34  *     if everyone increases the FILEVERSION number above, then scripts
  35  *     can do the right thing when deciding whether to install a new ppp-comp.h
  36  *     file.  Don't change the format of that line otherwise, so the
  37  *     installation script can recognize it.
  38  */
  39
  40 #ifndef _NET_PPP_COMP_H
  41 #define _NET_PPP_COMP_H
  42
  43 struct module;
  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         /* 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 #ifdef __KERNEL__
 210 extern int ppp_register_compressor(struct compressor *);
 211 extern void ppp_unregister_compressor(struct compressor *);
 212 #endif /* __KERNEL__ */
 213
 214 #endif /* _NET_PPP_COMP_H */