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/*

 * ppp_comp.h - Definitions for doing PPP packet compression.

 *

 * Copyright (c) 1994 The Australian National University.

 * All rights reserved.

 *

 * Permission to use, copy, modify, and distribute this software and its

 * documentation is hereby granted, provided that the above copyright

 * notice appears in all copies.  This software is provided without any

 * warranty, express or implied. The Australian National University

 * makes no representations about the suitability of this software for

 * any purpose.

 *

 * IN NO EVENT SHALL THE AUSTRALIAN NATIONAL UNIVERSITY BE LIABLE TO ANY

 * PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES

 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF

 * THE AUSTRALIAN NATIONAL UNIVERSITY HAVE BEEN ADVISED OF THE POSSIBILITY

 * OF SUCH DAMAGE.

 *

 * THE AUSTRALIAN NATIONAL UNIVERSITY SPECIFICALLY DISCLAIMS ANY WARRANTIES,

 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY

 * AND FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS

 * ON AN "AS IS" BASIS, AND THE AUSTRALIAN NATIONAL UNIVERSITY HAS NO

 * OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS,

 * OR MODIFICATIONS.

 *

 * $FreeBSD: src/sys/net/ppp_comp.h,v 1.11 2002/03/24 09:34:04 bde Exp $

 */

#ifndef _NET_PPP_COMP_H

#define _NET_PPP_COMP_H

/*

 * Structure giving methods for compression/decompression.

 */

#ifdef PACKETPTR

struct compressor {

        int     compress_proto; /* CCP compression protocol number */

        /* Allocate space for a compressor (transmit side) */

        void    *(*comp_alloc)(u_char *options, int opt_len);

        /* Free space used by a compressor */

        void    (*comp_free)(void *state);

        /* Initialize a compressor */

        int     (*comp_init)(void *state, u_char *options, int opt_len,

                    int unit, int hdrlen, int debug);

        /* Reset a compressor */

        void    (*comp_reset)(void *state);

        /* Compress a packet */

        int     (*compress)(void *state, PACKETPTR *mret, PACKETPTR mp,

                    int orig_len, int max_len);

        /* Return compression statistics */

        void    (*comp_stat)(void *state, struct compstat *stats);

        /* Allocate space for a decompressor (receive side) */

        void    *(*decomp_alloc)(u_char *options, int opt_len);

        /* Free space used by a decompressor */

        void    (*decomp_free)(void *state);

        /* Initialize a decompressor */

        int     (*decomp_init)(void *state, u_char *options, int opt_len,

                    int unit, int hdrlen, int mru, int debug);

        /* Reset a decompressor */

        void    (*decomp_reset)(void *state);

        /* Decompress a packet. */

        int     (*decompress)(void *state, PACKETPTR mp, PACKETPTR *dmpp);

        /* Update state for an incompressible packet received */

        void    (*incomp)(void *state, PACKETPTR mp);

        /* Return decompression statistics */

        void    (*decomp_stat)(void *state, struct compstat *stats);

};

#endif /* PACKETPTR */

/*

 * Return values for decompress routine.

 * We need to make these distinctions so that we can disable certain

 * useful functionality, namely sending a CCP reset-request as a result

 * of an error detected after decompression.  This is to avoid infringing

 * a patent held by Motorola.

 * Don't you just lurve software patents.

 */

#define DECOMP_OK               0        /* everything went OK */

#define DECOMP_ERROR            1       /* error detected before decomp. */

#define DECOMP_FATALERROR       2       /* error detected after decomp. */

/*

 * CCP codes.

 */

#define CCP_CONFREQ     1

#define CCP_CONFACK     2

#define CCP_TERMREQ     5

#define CCP_TERMACK     6

#define CCP_RESETREQ    14

#define CCP_RESETACK    15

/*

 * Max # bytes for a CCP option

 */

#define CCP_MAX_OPTION_LENGTH   32

/*

 * Parts of a CCP packet.

 */

#define CCP_CODE(dp)            ((dp)[0])

#define CCP_ID(dp)              ((dp)[1])

#define CCP_LENGTH(dp)          (((dp)[2] << 8) + (dp)[3])

#define CCP_HDRLEN              4

#define CCP_OPT_CODE(dp)        ((dp)[0])

#define CCP_OPT_LENGTH(dp)      ((dp)[1])

#define CCP_OPT_MINLEN          2

/*

 * Definitions for BSD-Compress.

 */

#define CI_BSD_COMPRESS         21      /* config. option for BSD-Compress */

#define CILEN_BSD_COMPRESS      3       /* length of config. option */

/* Macros for handling the 3rd byte of the BSD-Compress config option. */

#define BSD_NBITS(x)            ((x) & 0x1F)    /* number of bits requested */

#define BSD_VERSION(x)          ((x) >> 5)      /* version of option format */

#define BSD_CURRENT_VERSION     1               /* current version number */

#define BSD_MAKE_OPT(v, n)      (((v) << 5) | (n))

#define BSD_MIN_BITS            9       /* smallest code size supported */

#define BSD_MAX_BITS            15      /* largest code size supported */

/*

 * Definitions for Deflate.

 */

#define CI_DEFLATE              26      /* config option for Deflate */

#define CI_DEFLATE_DRAFT        24      /* value used in original draft RFC */

#define CILEN_DEFLATE           4       /* length of its config option */

#define DEFLATE_MIN_SIZE        8

#define DEFLATE_MAX_SIZE        15

#define DEFLATE_METHOD_VAL      8

#define DEFLATE_SIZE(x)         (((x) >> 4) + DEFLATE_MIN_SIZE)

#define DEFLATE_METHOD(x)       ((x) & 0x0F)

#define DEFLATE_MAKE_OPT(w)     ((((w) - DEFLATE_MIN_SIZE) << 4) \

                                 + DEFLATE_METHOD_VAL)

#define DEFLATE_CHK_SEQUENCE    0

/*

 * Definitions for other, as yet unsupported, compression methods.

 */

#define CI_PREDICTOR_1          1       /* config option for Predictor-1 */

#define CILEN_PREDICTOR_1       2       /* length of its config option */

#define CI_PREDICTOR_2          2       /* config option for Predictor-2 */

#define CILEN_PREDICTOR_2       2       /* length of its config option */

#endif /* _NET_PPP_COMP_H */