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