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
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 extern int ppp_register_compressor(struct compressor *);
102 extern void ppp_unregister_compressor(struct compressor *);
103 #endif /* _NET_PPP_COMP_H */