LXR linux/include/linux/ppp-comp.h

   1/* SPDX-License-Identifier: GPL-2.0-only */
   2/*
   3 * ppp-comp.h - Definitions for doing PPP packet compression.
   4 *
   5 * Copyright 1994-1998 Paul Mackerras.
   6 */
   7#ifndef _NET_PPP_COMP_H
   8#define _NET_PPP_COMP_H
   9
  10#include <uapi/linux/ppp-comp.h>
  11
  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
 101extern int ppp_register_compressor(struct compressor *);
 102extern void ppp_unregister_compressor(struct compressor *);
 103#endif /* _NET_PPP_COMP_H */
 104