linux/include/linux/ppp-comp.h
<<
>>
Prefs
   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
  13struct 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
  33struct 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__
 180extern int ppp_register_compressor(struct compressor *);
 181extern void ppp_unregister_compressor(struct compressor *);
 182#endif /* __KERNEL__ */
 183
 184#endif /* _NET_PPP_COMP_H */
 185
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.