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      1 /*
      2  * ppp-comp.h - Definitions for doing PPP packet compression.
      3  *
      4  * Copyright (c) 1984 Paul Mackerras. All rights reserved.
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  *
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  *
     13  * 2. Redistributions in binary form must reproduce the above copyright
     14  *    notice, this list of conditions and the following disclaimer in
     15  *    the documentation and/or other materials provided with the
     16  *    distribution.
     17  *
     18  * 3. The name(s) of the authors of this software must not be used to
     19  *    endorse or promote products derived from this software without
     20  *    prior written permission.
     21  *
     22  * 4. Redistributions of any form whatsoever must retain the following
     23  *    acknowledgment:
     24  *    "This product includes software developed by Paul Mackerras
     25  *     <paulus (at) samba.org>".
     26  *
     27  * THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
     28  * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
     29  * AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
     30  * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
     31  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
     32  * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
     33  * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
     34  *
     35  * $Id: ppp-comp.h,v 1.13 2002/12/06 09:49:15 paulus Exp $
     36  */
     37 
     38 #ifndef _NET_PPP_COMP_H
     39 #define _NET_PPP_COMP_H
     40 
     41 /*
     42  * The following symbols control whether we include code for
     43  * various compression methods.
     44  */
     45 #ifndef DO_BSD_COMPRESS
     46 #define DO_BSD_COMPRESS	1	/* by default, include BSD-Compress */
     47 #endif
     48 #ifndef DO_DEFLATE
     49 #define DO_DEFLATE	1	/* by default, include Deflate */
     50 #endif
     51 #define DO_PREDICTOR_1	0
     52 #define DO_PREDICTOR_2	0
     53 
     54 /*
     55  * Structure giving methods for compression/decompression.
     56  */
     57 #ifdef PACKETPTR
     58 struct compressor {
     59 	int	compress_proto;	/* CCP compression protocol number */
     60 
     61 	/* Allocate space for a compressor (transmit side) */
     62 	void	*(*comp_alloc) __P((u_char *options, int opt_len));
     63 	/* Free space used by a compressor */
     64 	void	(*comp_free) __P((void *state));
     65 	/* Initialize a compressor */
     66 	int	(*comp_init) __P((void *state, u_char *options, int opt_len,
     67 				  int unit, int hdrlen, int debug));
     68 	/* Reset a compressor */
     69 	void	(*comp_reset) __P((void *state));
     70 	/* Compress a packet */
     71 	int	(*compress) __P((void *state, PACKETPTR *mret,
     72 				 PACKETPTR mp, int orig_len, int max_len));
     73 	/* Return compression statistics */
     74 	void	(*comp_stat) __P((void *state, struct compstat *stats));
     75 
     76 	/* Allocate space for a decompressor (receive side) */
     77 	void	*(*decomp_alloc) __P((u_char *options, int opt_len));
     78 	/* Free space used by a decompressor */
     79 	void	(*decomp_free) __P((void *state));
     80 	/* Initialize a decompressor */
     81 	int	(*decomp_init) __P((void *state, u_char *options, int opt_len,
     82 				    int unit, int hdrlen, int mru, int debug));
     83 	/* Reset a decompressor */
     84 	void	(*decomp_reset) __P((void *state));
     85 	/* Decompress a packet. */
     86 	int	(*decompress) __P((void *state, PACKETPTR mp,
     87 				   PACKETPTR *dmpp));
     88 	/* Update state for an incompressible packet received */
     89 	void	(*incomp) __P((void *state, PACKETPTR mp));
     90 	/* Return decompression statistics */
     91 	void	(*decomp_stat) __P((void *state, struct compstat *stats));
     92 };
     93 #endif /* PACKETPTR */
     94 
     95 /*
     96  * Return values for decompress routine.
     97  * We need to make these distinctions so that we can disable certain
     98  * useful functionality, namely sending a CCP reset-request as a result
     99  * of an error detected after decompression.  This is to avoid infringing
    100  * a patent held by Motorola.
    101  * Don't you just lurve software patents.
    102  */
    103 #define DECOMP_OK		0	/* everything went OK */
    104 #define DECOMP_ERROR		1	/* error detected before decomp. */
    105 #define DECOMP_FATALERROR	2	/* error detected after decomp. */
    106 
    107 /*
    108  * CCP codes.
    109  */
    110 #define CCP_CONFREQ	1
    111 #define CCP_CONFACK	2
    112 #define CCP_TERMREQ	5
    113 #define CCP_TERMACK	6
    114 #define CCP_RESETREQ	14
    115 #define CCP_RESETACK	15
    116 
    117 /*
    118  * Max # bytes for a CCP option
    119  */
    120 #define CCP_MAX_OPTION_LENGTH	32
    121 
    122 /*
    123  * Parts of a CCP packet.
    124  */
    125 #define CCP_CODE(dp)		((dp)[0])
    126 #define CCP_ID(dp)		((dp)[1])
    127 #define CCP_LENGTH(dp)		(((dp)[2] << 8) + (dp)[3])
    128 #define CCP_HDRLEN		4
    129 
    130 #define CCP_OPT_CODE(dp)	((dp)[0])
    131 #define CCP_OPT_LENGTH(dp)	((dp)[1])
    132 #define CCP_OPT_MINLEN		2
    133 
    134 /*
    135  * Definitions for BSD-Compress.
    136  */
    137 #define CI_BSD_COMPRESS		21	/* config. option for BSD-Compress */
    138 #define CILEN_BSD_COMPRESS	3	/* length of config. option */
    139 
    140 /* Macros for handling the 3rd byte of the BSD-Compress config option. */
    141 #define BSD_NBITS(x)		((x) & 0x1F)	/* number of bits requested */
    142 #define BSD_VERSION(x)		((x) >> 5)	/* version of option format */
    143 #define BSD_CURRENT_VERSION	1		/* current version number */
    144 #define BSD_MAKE_OPT(v, n)	(((v) << 5) | (n))
    145 
    146 #define BSD_MIN_BITS		9	/* smallest code size supported */
    147 #define BSD_MAX_BITS		15	/* largest code size supported */
    148 
    149 /*
    150  * Definitions for Deflate.
    151  */
    152 #define CI_DEFLATE		26	/* config option for Deflate */
    153 #define CI_DEFLATE_DRAFT	24	/* value used in original draft RFC */
    154 #define CILEN_DEFLATE		4	/* length of its config option */
    155 
    156 #define DEFLATE_MIN_SIZE	8
    157 #define DEFLATE_MAX_SIZE	15
    158 #define DEFLATE_METHOD_VAL	8
    159 #define DEFLATE_SIZE(x)		(((x) >> 4) + DEFLATE_MIN_SIZE)
    160 #define DEFLATE_METHOD(x)	((x) & 0x0F)
    161 #define DEFLATE_MAKE_OPT(w)	((((w) - DEFLATE_MIN_SIZE) << 4) \
    162 				 + DEFLATE_METHOD_VAL)
    163 #define DEFLATE_CHK_SEQUENCE	0
    164 
    165 /*
    166  * Definitions for MPPE.
    167  */
    168 #define CI_MPPE			18	/* config option for MPPE */
    169 #define CILEN_MPPE		6	/* length of config option */
    170 
    171 #define MPPE_PAD		4	/* MPPE growth per frame */
    172 #define MPPE_MAX_KEY_LEN	16	/* largest key length (128-bit) */
    173 
    174 /* option bits for ccp_options.mppe */
    175 #define MPPE_OPT_40		0x01	/* 40 bit */
    176 #define MPPE_OPT_128		0x02	/* 128 bit */
    177 #define MPPE_OPT_STATEFUL	0x04	/* stateful mode */
    178 /* unsupported opts */
    179 #define MPPE_OPT_56		0x08	/* 56 bit */
    180 #define MPPE_OPT_MPPC		0x10	/* MPPC compression */
    181 #define MPPE_OPT_D		0x20	/* Unknown */
    182 #define MPPE_OPT_UNSUPPORTED (MPPE_OPT_56|MPPE_OPT_MPPC|MPPE_OPT_D)
    183 #define MPPE_OPT_UNKNOWN	0x40	/* Bits !defined in RFC 3078 were set */
    184 
    185 /*
    186  * This is not nice ... the alternative is a bitfield struct though.
    187  * And unfortunately, we cannot share the same bits for the option
    188  * names above since C and H are the same bit.  We could do a u_int32
    189  * but then we have to do a htonl() all the time and/or we still need
    190  * to know which octet is which.
    191  */
    192 #define MPPE_C_BIT		0x01	/* MPPC */
    193 #define MPPE_D_BIT		0x10	/* Obsolete, usage unknown */
    194 #define MPPE_L_BIT		0x20	/* 40-bit */
    195 #define MPPE_S_BIT		0x40	/* 128-bit */
    196 #define MPPE_M_BIT		0x80	/* 56-bit, not supported */
    197 #define MPPE_H_BIT		0x01	/* Stateless (in a different byte) */
    198 
    199 /* Does not include H bit; used for least significant octet only. */
    200 #define MPPE_ALL_BITS (MPPE_D_BIT|MPPE_L_BIT|MPPE_S_BIT|MPPE_M_BIT|MPPE_H_BIT)
    201 
    202 /* Build a CI from mppe opts (see RFC 3078) */
    203 #define MPPE_OPTS_TO_CI(opts, ci)		\
    204     do {					\
    205 	u_char *ptr = ci; /* u_char[4] */	\
    206 						\
    207 	/* H bit */				\
    208 	if (opts & MPPE_OPT_STATEFUL)		\
    209 	    *ptr++ = 0x0;			\
    210 	else					\
    211 	    *ptr++ = MPPE_H_BIT;		\
    212 	*ptr++ = 0;				\
    213 	*ptr++ = 0;				\
    214 						\
    215 	/* S,L bits */				\
    216 	*ptr = 0;				\
    217 	if (opts & MPPE_OPT_128)		\
    218 	    *ptr |= MPPE_S_BIT;			\
    219 	if (opts & MPPE_OPT_40)			\
    220 	    *ptr |= MPPE_L_BIT;			\
    221 	/* M,D,C bits not supported */		\
    222     } while (/* CONSTCOND */ 0)
    223 
    224 /* The reverse of the above */
    225 #define MPPE_CI_TO_OPTS(ci, opts)		\
    226     do {					\
    227 	u_char *ptr = ci; /* u_char[4] */	\
    228 						\
    229 	opts = 0;				\
    230 						\
    231 	/* H bit */				\
    232 	if (!(ptr[0] & MPPE_H_BIT))		\
    233 	    opts |= MPPE_OPT_STATEFUL;		\
    234 						\
    235 	/* S,L bits */				\
    236 	if (ptr[3] & MPPE_S_BIT)		\
    237 	    opts |= MPPE_OPT_128;		\
    238 	if (ptr[3] & MPPE_L_BIT)		\
    239 	    opts |= MPPE_OPT_40;		\
    240 						\
    241 	/* M,D,C bits */			\
    242 	if (ptr[3] & MPPE_M_BIT)		\
    243 	    opts |= MPPE_OPT_56;		\
    244 	if (ptr[3] & MPPE_D_BIT)		\
    245 	    opts |= MPPE_OPT_D;			\
    246 	if (ptr[3] & MPPE_C_BIT)		\
    247 	    opts |= MPPE_OPT_MPPC;		\
    248 						\
    249 	/* Other bits */			\
    250 	if (ptr[0] & ~MPPE_H_BIT)		\
    251 	    opts |= MPPE_OPT_UNKNOWN;		\
    252 	if (ptr[1] || ptr[2])			\
    253 	    opts |= MPPE_OPT_UNKNOWN;		\
    254 	if (ptr[3] & ~MPPE_ALL_BITS)		\
    255 	    opts |= MPPE_OPT_UNKNOWN;		\
    256     } while (/* CONSTCOND */ 0)
    257 
    258 /*
    259  * Definitions for other, as yet unsupported, compression methods.
    260  */
    261 #define CI_PREDICTOR_1		1	/* config option for Predictor-1 */
    262 #define CILEN_PREDICTOR_1	2	/* length of its config option */
    263 #define CI_PREDICTOR_2		2	/* config option for Predictor-2 */
    264 #define CILEN_PREDICTOR_2	2	/* length of its config option */
    265 
    266 #endif /* _NET_PPP_COMP_H */
    267