include/linux/ppp-comp.h

   1 /*
   2  * ppp-comp.h - Definitions for doing PPP packet compression.
   3  *
   4  * Copyright 1994-1998 Paul Mackerras.
   5  *
   6  *  This program is free software; you can redistribute it and/or
   7  *  modify it under the terms of the GNU General Public License
   8  *  version 2 as published by the Free Software Foundation.
   9  */
  10 #ifndef _NET_PPP_COMP_H
  11 #define _NET_PPP_COMP_H
  12
  13 #ifdef __KERNEL__
  14
  15 struct module;
  16
  17 /*
  18  * The following symbols control whether we include code for
  19  * various compression methods.
  20  */
  21
  22 #ifndef DO_BSD_COMPRESS
  23 #define DO_BSD_COMPRESS 1       /* by default, include BSD-Compress */
  24 #endif
  25 #ifndef DO_DEFLATE
  26 #define DO_DEFLATE      1       /* by default, include Deflate */
  27 #endif
  28 #define DO_PREDICTOR_1  0
  29 #define DO_PREDICTOR_2  0
  30
  31 /*
  32  * Structure giving methods for compression/decompression.
  33  */
  34
  35 struct compressor {
  36         int     compress_proto; /* CCP compression protocol number */
  37
  38         /* Allocate space for a compressor (transmit side) */
  39         void    *(*comp_alloc) (unsigned char *options, int opt_len);
  40
  41         /* Free space used by a compressor */
  42         void    (*comp_free) (void *state);
  43
  44         /* Initialize a compressor */
  45         int     (*comp_init) (void *state, unsigned char *options,
  46                               int opt_len, int unit, int opthdr, int debug);
  47
  48         /* Reset a compressor */
  49         void    (*comp_reset) (void *state);
  50
  51         /* Compress a packet */
  52         int     (*compress) (void *state, unsigned char *rptr,
  53                               unsigned char *obuf, int isize, int osize);
  54
  55         /* Return compression statistics */
  56         void    (*comp_stat) (void *state, struct compstat *stats);
  57
  58         /* Allocate space for a decompressor (receive side) */
  59         void    *(*decomp_alloc) (unsigned char *options, int opt_len);
  60
  61         /* Free space used by a decompressor */
  62         void    (*decomp_free) (void *state);
  63
  64         /* Initialize a decompressor */
  65         int     (*decomp_init) (void *state, unsigned char *options,
  66                                 int opt_len, int unit, int opthdr, int mru,
  67                                 int debug);
  68
  69         /* Reset a decompressor */
  70         void    (*decomp_reset) (void *state);
  71
  72         /* Decompress a packet. */
  73         int     (*decompress) (void *state, unsigned char *ibuf, int isize,
  74                                 unsigned char *obuf, int osize);
  75
  76         /* Update state for an incompressible packet received */
  77         void    (*incomp) (void *state, unsigned char *ibuf, int icnt);
  78
  79         /* Return decompression statistics */
  80         void    (*decomp_stat) (void *state, struct compstat *stats);
  81
  82         /* Used in locking compressor modules */
  83         struct module *owner;
  84         /* Extra skb space needed by the compressor algorithm */
  85         unsigned int comp_extra;
  86 };
  87
  88 /*
  89  * The return value from decompress routine is the length of the
  90  * decompressed packet if successful, otherwise DECOMP_ERROR
  91  * or DECOMP_FATALERROR if an error occurred.
  92  *
  93  * We need to make this distinction so that we can disable certain
  94  * useful functionality, namely sending a CCP reset-request as a result
  95  * of an error detected after decompression.  This is to avoid infringing
  96  * a patent held by Motorola.
  97  * Don't you just lurve software patents.
  98  */
  99
 100 #define DECOMP_ERROR            -1      /* error detected before decomp. */
 101 #define DECOMP_FATALERROR       -2      /* error detected after decomp. */
 102
 103 #endif /* __KERNEL__ */
 104
 105 /*
 106  * CCP codes.
 107  */
 108
 109 #define CCP_CONFREQ     1
 110 #define CCP_CONFACK     2
 111 #define CCP_TERMREQ     5
 112 #define CCP_TERMACK     6
 113 #define CCP_RESETREQ    14
 114 #define CCP_RESETACK    15
 115
 116 /*
 117  * Max # bytes for a CCP option
 118  */
 119
 120 #define CCP_MAX_OPTION_LENGTH   32
 121
 122 /*
 123  * Parts of a CCP packet.
 124  */
 125
 126 #define CCP_CODE(dp)            ((dp)[0])
 127 #define CCP_ID(dp)              ((dp)[1])
 128 #define CCP_LENGTH(dp)          (((dp)[2] << 8) + (dp)[3])
 129 #define CCP_HDRLEN              4
 130
 131 #define CCP_OPT_CODE(dp)        ((dp)[0])
 132 #define CCP_OPT_LENGTH(dp)      ((dp)[1])
 133 #define CCP_OPT_MINLEN          2
 134
 135 /*
 136  * Definitions for BSD-Compress.
 137  */
 138
 139 #define CI_BSD_COMPRESS         21      /* config. option for BSD-Compress */
 140 #define CILEN_BSD_COMPRESS      3       /* length of config. option */
 141
 142 /* Macros for handling the 3rd byte of the BSD-Compress config option. */
 143 #define BSD_NBITS(x)            ((x) & 0x1F)    /* number of bits requested */
 144 #define BSD_VERSION(x)          ((x) >> 5)      /* version of option format */
 145 #define BSD_CURRENT_VERSION     1               /* current version number */
 146 #define BSD_MAKE_OPT(v, n)      (((v) << 5) | (n))
 147
 148 #define BSD_MIN_BITS            9       /* smallest code size supported */
 149 #define BSD_MAX_BITS            15      /* largest code size supported */
 150
 151 /*
 152  * Definitions for Deflate.
 153  */
 154
 155 #define CI_DEFLATE              26      /* config option for Deflate */
 156 #define CI_DEFLATE_DRAFT        24      /* value used in original draft RFC */
 157 #define CILEN_DEFLATE           4       /* length of its config option */
 158
 159 #define DEFLATE_MIN_SIZE        9
 160 #define DEFLATE_MAX_SIZE        15
 161 #define DEFLATE_METHOD_VAL      8
 162 #define DEFLATE_SIZE(x)         (((x) >> 4) + 8)
 163 #define DEFLATE_METHOD(x)       ((x) & 0x0F)
 164 #define DEFLATE_MAKE_OPT(w)     ((((w) - 8) << 4) + DEFLATE_METHOD_VAL)
 165 #define DEFLATE_CHK_SEQUENCE    0
 166
 167 /*
 168  * Definitions for MPPE.
 169  */
 170
 171 #define CI_MPPE                18      /* config option for MPPE */
 172 #define CILEN_MPPE              6      /* length of config option */
 173
 174 /*
 175  * Definitions for other, as yet unsupported, compression methods.
 176  */
 177
 178 #define CI_PREDICTOR_1          1       /* config option for Predictor-1 */
 179 #define CILEN_PREDICTOR_1       2       /* length of its config option */
 180 #define CI_PREDICTOR_2          2       /* config option for Predictor-2 */
 181 #define CILEN_PREDICTOR_2       2       /* length of its config option */
 182
 183 #ifdef __KERNEL__
 184 extern int ppp_register_compressor(struct compressor *);
 185 extern void ppp_unregister_compressor(struct compressor *);
 186 #endif /* __KERNEL__ */
 187
 188 #endif /* _NET_PPP_COMP_H */