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 */ 189