release/src/router/pppd/include/linux/ppp-comp.h

   1 /*
   2  * ppp-comp.h - Definitions for doing PPP packet compression.
   3  *
   4  * Copyright (c) 1984 Paul Mackerras. All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  *
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in
  15  *    the documentation and/or other materials provided with the
  16  *    distribution.
  17  *
  18  * 3. The name(s) of the authors of this software must not be used to
  19  *    endorse or promote products derived from this software without
  20  *    prior written permission.
  21  *
  22  * 4. Redistributions of any form whatsoever must retain the following
  23  *    acknowledgment:
  24  *    "This product includes software developed by Paul Mackerras
  25  *     <paulus@samba.org>".
  26  *
  27  * THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
  28  * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
  29  * AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
  30  * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  31  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
  32  * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
  33  * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  34  *
  35  * $Id: ppp-comp.h,v 1.10 2002/12/06 09:49:15 paulus Exp $
  36  */
  37
  38 /*
  39  *  ==FILEVERSION 20020715==
  40  *
  41  *  NOTE TO MAINTAINERS:
  42  *     If you modify this file at all, please set the above date.
  43  *     ppp-comp.h is shipped with a PPP distribution as well as with the kernel;
  44  *     if everyone increases the FILEVERSION number above, then scripts
  45  *     can do the right thing when deciding whether to install a new ppp-comp.h
  46  *     file.  Don't change the format of that line otherwise, so the
  47  *     installation script can recognize it.
  48  */
  49
  50 #ifndef _NET_PPP_COMP_H
  51 #define _NET_PPP_COMP_H
  52
  53 /*
  54  * The following symbols control whether we include code for
  55  * various compression methods.
  56  */
  57
  58 #ifndef DO_BSD_COMPRESS
  59 #define DO_BSD_COMPRESS 1       /* by default, include BSD-Compress */
  60 #endif
  61 #ifndef DO_DEFLATE
  62 #define DO_DEFLATE      1       /* by default, include Deflate */
  63 #endif
  64 #define DO_PREDICTOR_1  0
  65 #define DO_PREDICTOR_2  0
  66
  67 /*
  68  * Structure giving methods for compression/decompression.
  69  */
  70
  71 struct compressor {
  72         int     compress_proto; /* CCP compression protocol number */
  73
  74         /* Allocate space for a compressor (transmit side) */
  75         void    *(*comp_alloc) (unsigned char *options, int opt_len);
  76
  77         /* Free space used by a compressor */
  78         void    (*comp_free) (void *state);
  79
  80         /* Initialize a compressor */
  81         int     (*comp_init) (void *state, unsigned char *options,
  82                               int opt_len, int unit, int opthdr, int debug);
  83
  84         /* Reset a compressor */
  85         void    (*comp_reset) (void *state);
  86
  87         /* Compress a packet */
  88         int     (*compress) (void *state, unsigned char *rptr,
  89                               unsigned char *obuf, int isize, int osize);
  90
  91         /* Return compression statistics */
  92         void    (*comp_stat) (void *state, struct compstat *stats);
  93
  94         /* Allocate space for a decompressor (receive side) */
  95         void    *(*decomp_alloc) (unsigned char *options, int opt_len);
  96
  97         /* Free space used by a decompressor */
  98         void    (*decomp_free) (void *state);
  99
 100         /* Initialize a decompressor */
 101         int     (*decomp_init) (void *state, unsigned char *options,
 102                                 int opt_len, int unit, int opthdr, int mru,
 103                                 int debug);
 104
 105         /* Reset a decompressor */
 106         void    (*decomp_reset) (void *state);
 107
 108         /* Decompress a packet. */
 109         int     (*decompress) (void *state, unsigned char *ibuf, int isize,
 110                                 unsigned char *obuf, int osize);
 111
 112         /* Update state for an incompressible packet received */
 113         void    (*incomp) (void *state, unsigned char *ibuf, int icnt);
 114
 115         /* Return decompression statistics */
 116         void    (*decomp_stat) (void *state, struct compstat *stats);
 117 };
 118
 119 /*
 120  * The return value from decompress routine is the length of the
 121  * decompressed packet if successful, otherwise DECOMP_ERROR
 122  * or DECOMP_FATALERROR if an error occurred.
 123  *
 124  * We need to make this distinction so that we can disable certain
 125  * useful functionality, namely sending a CCP reset-request as a result
 126  * of an error detected after decompression.  This is to avoid infringing
 127  * a patent held by Motorola.
 128  * Don't you just lurve software patents.
 129  */
 130
 131 #define DECOMP_ERROR            -1      /* error detected before decomp. */
 132 #define DECOMP_FATALERROR       -2      /* error detected after decomp. */
 133
 134 /*
 135  * CCP codes.
 136  */
 137
 138 #define CCP_CONFREQ     1
 139 #define CCP_CONFACK     2
 140 #define CCP_TERMREQ     5
 141 #define CCP_TERMACK     6
 142 #define CCP_RESETREQ    14
 143 #define CCP_RESETACK    15
 144
 145 /*
 146  * Max # bytes for a CCP option
 147  */
 148
 149 #define CCP_MAX_OPTION_LENGTH   32
 150
 151 /*
 152  * Parts of a CCP packet.
 153  */
 154
 155 #define CCP_CODE(dp)            ((dp)[0])
 156 #define CCP_ID(dp)              ((dp)[1])
 157 #define CCP_LENGTH(dp)          (((dp)[2] << 8) + (dp)[3])
 158 #define CCP_HDRLEN              4
 159
 160 #define CCP_OPT_CODE(dp)        ((dp)[0])
 161 #define CCP_OPT_LENGTH(dp)      ((dp)[1])
 162 #define CCP_OPT_MINLEN          2
 163
 164 /*
 165  * Definitions for BSD-Compress.
 166  */
 167
 168 #define CI_BSD_COMPRESS         21      /* config. option for BSD-Compress */
 169 #define CILEN_BSD_COMPRESS      3       /* length of config. option */
 170
 171 /* Macros for handling the 3rd byte of the BSD-Compress config option. */
 172 #define BSD_NBITS(x)            ((x) & 0x1F)    /* number of bits requested */
 173 #define BSD_VERSION(x)          ((x) >> 5)      /* version of option format */
 174 #define BSD_CURRENT_VERSION     1               /* current version number */
 175 #define BSD_MAKE_OPT(v, n)      (((v) << 5) | (n))
 176
 177 #define BSD_MIN_BITS            9       /* smallest code size supported */
 178 #define BSD_MAX_BITS            15      /* largest code size supported */
 179
 180 /*
 181  * Definitions for Deflate.
 182  */
 183
 184 #define CI_DEFLATE              26      /* config option for Deflate */
 185 #define CI_DEFLATE_DRAFT        24      /* value used in original draft RFC */
 186 #define CILEN_DEFLATE           4       /* length of its config option */
 187
 188 #define DEFLATE_MIN_SIZE        8
 189 #define DEFLATE_MAX_SIZE        15
 190 #define DEFLATE_METHOD_VAL      8
 191 #define DEFLATE_SIZE(x)         (((x) >> 4) + DEFLATE_MIN_SIZE)
 192 #define DEFLATE_METHOD(x)       ((x) & 0x0F)
 193 #define DEFLATE_MAKE_OPT(w)     ((((w) - DEFLATE_MIN_SIZE) << 4) \
 194                                  + DEFLATE_METHOD_VAL)
 195 #define DEFLATE_CHK_SEQUENCE    0
 196
 197 /*
 198  * Definitions for MPPE.
 199  */
 200
 201 #define CI_MPPE                 18      /* config option for MPPE */
 202 #define CILEN_MPPE              6       /* length of config option */
 203
 204 /* MPPE/MPPC definitions by J.D.*/
 205 #define MPPE_STATELESS          MPPE_H_BIT      /* configuration bit H */
 206 #define MPPE_40BIT              MPPE_L_BIT      /* configuration bit L */
 207 #define MPPE_56BIT              MPPE_M_BIT      /* configuration bit M */
 208 #define MPPE_128BIT             MPPE_S_BIT      /* configuration bit S */
 209 #define MPPE_MPPC               MPPE_C_BIT      /* configuration bit C */
 210
 211 /*
 212  * Definitions for Stac LZS.
 213  */
 214
 215 #define CI_LZS                  17      /* config option for Stac LZS */
 216 #define CILEN_LZS               5       /* length of config option */
 217
 218 #define LZS_OVHD                4       /* max. LZS overhead */
 219 #define LZS_HIST_LEN            2048    /* LZS history size */
 220 #define LZS_MAX_CCOUNT          0x0FFF  /* max. coherency counter value */
 221
 222 #define LZS_MODE_NONE           0
 223 #define LZS_MODE_LCB            1
 224 #define LZS_MODE_CRC            2
 225 #define LZS_MODE_SEQ            3
 226 #define LZS_MODE_EXT            4
 227
 228 #define LZS_EXT_BIT_FLUSHED     0x80    /* bit A */
 229 #define LZS_EXT_BIT_COMP        0x20    /* bit C */
 230
 231 /*
 232  * Definitions for other, as yet unsupported, compression methods.
 233  */
 234
 235 #define CI_PREDICTOR_1          1       /* config option for Predictor-1 */
 236 #define CILEN_PREDICTOR_1       2       /* length of its config option */
 237 #define CI_PREDICTOR_2          2       /* config option for Predictor-2 */
 238 #define CILEN_PREDICTOR_2       2       /* length of its config option */
 239
 240 #endif /* _NET_PPP_COMP_H */