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
12struct compstat;
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