/*      $NetBSD: ppp-comp.h,v 1.16 2008/11/29 23:15:20 cube Exp $       */

/*
* ppp-comp.h - Definitions for doing PPP packet compression.
*
* Copyright (c) 1989-2002 Paul Mackerras. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in
*    the documentation and/or other materials provided with the
*    distribution.
*
* 3. The name(s) of the authors of this software must not be used to
*    endorse or promote products derived from this software without
*    prior written permission.
*
* 4. Redistributions of any form whatsoever must retain the following
*    acknowledgment:
*    "This product includes software developed by Paul Mackerras
*     <[email protected]>".
*
* THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
* THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
* SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
* AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
* OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/

#ifndef _NET_PPP_COMP_H_
#define _NET_PPP_COMP_H_

/*
* 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

/*
* How many entries to make available in the compressors table
*/
#ifndef PPP_COMPRESSORS_MAX
#define PPP_COMPRESSORS_MAX     8
#endif

/*
* Structure giving methods for compression/decompression.
*/
#ifdef PACKETPTR
#include <sys/queue.h>

struct compressor {
       int     compress_proto; /* CCP compression protocol number */

       /* Allocate space for a compressor (transmit side) */
       void    *(*comp_alloc)(u_char *, int);
       /* Free space used by a compressor */
       void    (*comp_free)(void *);
       /* Initialize a compressor */
       int     (*comp_init)(void *, u_char *, int, int, int, int);
       /* Reset a compressor */
       void    (*comp_reset)(void *);
       /* Compress a packet */
       int     (*compress)(void *, PACKETPTR *, PACKETPTR, int, int);
       /* Return compression statistics */
       void    (*comp_stat)(void *, struct compstat *);

       /* Allocate space for a decompressor (receive side) */
       void    *(*decomp_alloc)(u_char *, int);
       /* Free space used by a decompressor */
       void    (*decomp_free)(void *);
       /* Initialize a decompressor */
       int     (*decomp_init)(void *, u_char *, int, int, int, int, int);
       /* Reset a decompressor */
       void    (*decomp_reset)(void *);
       /* Decompress a packet. */
       int     (*decompress)(void *, PACKETPTR, PACKETPTR *);
       /* Update state for an incompressible packet received */
       void    (*incomp)(void *, PACKETPTR);
       /* Return decompression statistics */
       void    (*decomp_stat)(void *, struct compstat *);

       LIST_ENTRY(compressor)  comp_list;
       unsigned int            comp_refcnt;
};
#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_CONFNAK     3
#define CCP_CONFREJ     4
#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   64

/*
* 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 MPPE.
*/
#define CI_MPPE                 18      /* config option for MPPE */
#define CILEN_MPPE              6       /* length of config option */

#define MPPE_PAD                4       /* MPPE growth per frame */
#define MPPE_MAX_KEY_LEN        16      /* largest key length (128-bit) */

/* option bits for ccp_options.mppe */
#define MPPE_OPT_40             0x01    /* 40 bit */
#define MPPE_OPT_128            0x02    /* 128 bit */
#define MPPE_OPT_STATEFUL       0x04    /* stateful mode */
/* unsupported opts */
#define MPPE_OPT_56             0x08    /* 56 bit */
#define MPPE_OPT_MPPC           0x10    /* MPPC compression */
#define MPPE_OPT_D              0x20    /* Unknown */
#define MPPE_OPT_UNSUPPORTED (MPPE_OPT_56|MPPE_OPT_MPPC|MPPE_OPT_D)
#define MPPE_OPT_UNKNOWN        0x40    /* Bits !defined in RFC 3078 were set */

/*
* This is not nice ... the alternative is a bitfield struct though.
* And unfortunately, we cannot share the same bits for the option
* names above since C and H are the same bit.  We could do a uint32_t
* but then we have to do a htonl() all the time and/or we still need
* to know which octet is which.
*/
#define MPPE_C_BIT              0x01    /* MPPC */
#define MPPE_D_BIT              0x10    /* Obsolete, usage unknown */
#define MPPE_L_BIT              0x20    /* 40-bit */
#define MPPE_S_BIT              0x40    /* 128-bit */
#define MPPE_M_BIT              0x80    /* 56-bit, not supported */
#define MPPE_H_BIT              0x01    /* Stateless (in a different byte) */

/* Does not include H bit; used for least significant octet only. */
#define MPPE_ALL_BITS (MPPE_D_BIT|MPPE_L_BIT|MPPE_S_BIT|MPPE_M_BIT|MPPE_H_BIT)

/* Build a CI from mppe opts (see RFC 3078) */
#define MPPE_OPTS_TO_CI(opts, ci)               \
   do {                                        \
       u_char *ptr = ci; /* u_char[4] */       \
                                               \
       /* H bit */                             \
       if (opts & MPPE_OPT_STATEFUL)           \
           *ptr++ = 0x0;                       \
       else                                    \
           *ptr++ = MPPE_H_BIT;                \
       *ptr++ = 0;                             \
       *ptr++ = 0;                             \
                                               \
       /* S,L bits */                          \
       *ptr = 0;                               \
       if (opts & MPPE_OPT_128)                \
           *ptr |= MPPE_S_BIT;                 \
       if (opts & MPPE_OPT_40)                 \
           *ptr |= MPPE_L_BIT;                 \
       /* M,D,C bits not supported */          \
   } while (/* CONSTCOND */ 0)

/* The reverse of the above */
#define MPPE_CI_TO_OPTS(ci, opts)               \
   do {                                        \
       u_char *ptr = ci; /* u_char[4] */       \
                                               \
       opts = 0;                               \
                                               \
       /* H bit */                             \
       if (!(ptr[0] & MPPE_H_BIT))             \
           opts |= MPPE_OPT_STATEFUL;          \
                                               \
       /* S,L bits */                          \
       if (ptr[3] & MPPE_S_BIT)                \
           opts |= MPPE_OPT_128;               \
       if (ptr[3] & MPPE_L_BIT)                \
           opts |= MPPE_OPT_40;                \
                                               \
       /* M,D,C bits */                        \
       if (ptr[3] & MPPE_M_BIT)                \
           opts |= MPPE_OPT_56;                \
       if (ptr[3] & MPPE_D_BIT)                \
           opts |= MPPE_OPT_D;                 \
       if (ptr[3] & MPPE_C_BIT)                \
           opts |= MPPE_OPT_MPPC;              \
                                               \
       /* Other bits */                        \
       if (ptr[0] & ~MPPE_H_BIT)               \
           opts |= MPPE_OPT_UNKNOWN;           \
       if (ptr[1] || ptr[2])                   \
           opts |= MPPE_OPT_UNKNOWN;           \
       if (ptr[3] & ~MPPE_ALL_BITS)            \
           opts |= MPPE_OPT_UNKNOWN;           \
   } while (/* CONSTCOND */ 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_ */

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