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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.

 *

 * $Id: ppp-comp.h,v 1.6 1997/11/27 06:04:44 paulus Exp $

 */

/*

 *  ==FILEVERSION 980319==

 *

 *  NOTE TO MAINTAINERS:

 *     If you modify this file at all, please set the above date.

 *     ppp-comp.h is shipped with a PPP distribution as well as with the kernel;

 *     if everyone increases the FILEVERSION number above, then scripts

 *     can do the right thing when deciding whether to install a new ppp-comp.h

 *     file.  Don't change the format of that line otherwise, so the

 *     installation script can recognize it.

 */

#ifndef _NET_PPP_COMP_H

#define _NET_PPP_COMP_H

struct module;

/*

 * The following symbols control whether we include code for

 * various compression methods.

 */

#ifndef DO_BSD_COMPRESS

#define DO_BSD_COMPRESS 1       /* by default, include BSD-Compress */

#endif

#ifndef DO_DEFLATE

#define DO_DEFLATE      1       /* by default, include Deflate */

#endif

#define DO_PREDICTOR_1  0

#define DO_PREDICTOR_2  0

/*

 * Structure giving methods for compression/decompression.

 */

struct compressor {

        int     compress_proto; /* CCP compression protocol number */

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

        void    *(*comp_alloc) (unsigned char *options, int opt_len);

        /* Free space used by a compressor */

        void    (*comp_free) (void *state);

        /* Initialize a compressor */

        int     (*comp_init) (void *state, unsigned char *options,

                              int opt_len, int unit, int opthdr, int debug);

        /* Reset a compressor */

        void    (*comp_reset) (void *state);

        /* Compress a packet */

        int     (*compress) (void *state, unsigned char *rptr,

                              unsigned char *obuf, int isize, int osize);

        /* Return compression statistics */

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

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

        void    *(*decomp_alloc) (unsigned char *options, int opt_len);

        /* Free space used by a decompressor */

        void    (*decomp_free) (void *state);

        /* Initialize a decompressor */

        int     (*decomp_init) (void *state, unsigned char *options,

                                int opt_len, int unit, int opthdr, int mru,

                                int debug);

        /* Reset a decompressor */

        void    (*decomp_reset) (void *state);

        /* Decompress a packet. */

        int     (*decompress) (void *state, unsigned char *ibuf, int isize,

                                unsigned char *obuf, int osize);

        /* Update state for an incompressible packet received */

        void    (*incomp) (void *state, unsigned char *ibuf, int icnt);

        /* Return decompression statistics */

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

        /* Used in locking compressor modules */

        struct module *owner;

        /* Extra skb space needed by the compressor algorithm */

        unsigned int comp_extra;

};

/*

 * The return value from decompress routine is the length of the

 * decompressed packet if successful, otherwise DECOMP_ERROR

 * or DECOMP_FATALERROR if an error occurred.

 *

 * We need to make this distinction 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_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        9

#define DEFLATE_MAX_SIZE        15

#define DEFLATE_METHOD_VAL      8

#define DEFLATE_SIZE(x)         (((x) >> 4) + 8)

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

#define DEFLATE_MAKE_OPT(w)     ((((w) - 8) << 4) + DEFLATE_METHOD_VAL)

#define DEFLATE_CHK_SEQUENCE    0

/*

 * Definitions for MPPE.

 */

#define CI_MPPE                18      /* config option for MPPE */

#define CILEN_MPPE              6      /* length of config option */

/*

 * 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 */

#ifdef __KERNEL__

extern int ppp_register_compressor(struct compressor *);

extern void ppp_unregister_compressor(struct compressor *);

#endif /* __KERNEL__ */

#endif /* _NET_PPP_COMP_H */