contrib/bind-9.3/lib/dns/include/dns/compress.h

   1 /*
   2  * Copyright (C) 2004, 2006  Internet Systems Consortium, Inc. ("ISC")
   3  * Copyright (C) 1999-2002  Internet Software Consortium.
   4  *
   5  * Permission to use, copy, modify, and distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
  10  * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
  11  * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
  12  * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
  13  * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
  14  * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  15  * PERFORMANCE OF THIS SOFTWARE.
  16  */
  17
  18 /* $Id: compress.h,v 1.29.2.2.8.3 2006/03/02 00:37:20 marka Exp $ */
  19
  20 #ifndef DNS_COMPRESS_H
  21 #define DNS_COMPRESS_H 1
  22
  23 #include <isc/lang.h>
  24 #include <isc/region.h>
  25
  26 #include <dns/types.h>
  27
  28 ISC_LANG_BEGINDECLS
  29
  30 #define DNS_COMPRESS_NONE               0x00    /* no compression */
  31 #define DNS_COMPRESS_GLOBAL14           0x01    /* "normal" compression. */
  32 #define DNS_COMPRESS_ALL                0x01    /* all compression. */
  33
  34 /*
  35  *      Direct manipulation of the structures is strongly discouraged.
  36  */
  37
  38 #define DNS_COMPRESS_TABLESIZE 64
  39 #define DNS_COMPRESS_INITIALNODES 16
  40
  41 typedef struct dns_compressnode dns_compressnode_t;
  42
  43 struct dns_compressnode {
  44         isc_region_t            r;
  45         isc_uint16_t            offset;
  46         isc_uint16_t            count;
  47         isc_uint8_t             labels;
  48         dns_compressnode_t      *next;
  49 };
  50
  51 struct dns_compress {
  52         unsigned int            magic;          /* Magic number. */
  53         unsigned int            allowed;        /* Allowed methods. */
  54         int                     edns;           /* Edns version or -1. */
  55         /* Global compression table. */
  56         dns_compressnode_t      *table[DNS_COMPRESS_TABLESIZE];
  57         /* Preallocated nodes for the table. */
  58         dns_compressnode_t      initialnodes[DNS_COMPRESS_INITIALNODES];
  59         isc_uint16_t            count;          /* Number of nodes. */
  60         isc_mem_t               *mctx;          /* Memory context. */
  61 };
  62
  63 typedef enum {
  64         DNS_DECOMPRESS_ANY,                     /* Any compression */
  65         DNS_DECOMPRESS_STRICT,                  /* Allowed compression */
  66         DNS_DECOMPRESS_NONE                     /* No compression */
  67 } dns_decompresstype_t;
  68
  69 struct dns_decompress {
  70         unsigned int            magic;          /* Magic number. */
  71         unsigned int            allowed;        /* Allowed methods. */
  72         int                     edns;           /* Edns version or -1. */
  73         dns_decompresstype_t    type;           /* Strict checking */
  74 };
  75
  76 isc_result_t
  77 dns_compress_init(dns_compress_t *cctx, int edns, isc_mem_t *mctx);
  78 /*
  79  *      Inialise the compression context structure pointed to by 'cctx'.
  80  *
  81  *      Requires:
  82  *              'cctx' is a valid dns_compress_t structure.
  83  *              'mctx' is an initialized memory context.
  84  *      Ensures:
  85  *              cctx->global is initialized.
  86  *
  87  *      Returns:
  88  *              ISC_R_SUCCESS
  89  *              failures from dns_rbt_create()
  90  */
  91
  92 void
  93 dns_compress_invalidate(dns_compress_t *cctx);
  94
  95 /*
  96  *      Invalidate the compression structure pointed to by cctx.
  97  *
  98  *      Requires:
  99  *              'cctx' to be initialized.
 100  */
 101
 102 void
 103 dns_compress_setmethods(dns_compress_t *cctx, unsigned int allowed);
 104
 105 /*
 106  *      Sets allowed compression methods.
 107  *
 108  *      Requires:
 109  *              'cctx' to be initialized.
 110  */
 111
 112 unsigned int
 113 dns_compress_getmethods(dns_compress_t *cctx);
 114
 115 /*
 116  *      Gets allowed compression methods.
 117  *
 118  *      Requires:
 119  *              'cctx' to be initialized.
 120  *
 121  *      Returns:
 122  *              allowed compression bitmap.
 123  */
 124
 125 int
 126 dns_compress_getedns(dns_compress_t *cctx);
 127
 128 /*
 129  *      Gets edns value.
 130  *
 131  *      Requires:
 132  *              'cctx' to be initialized.
 133  *
 134  *      Returns:
 135  *              -1 .. 255
 136  */
 137
 138 isc_boolean_t
 139 dns_compress_findglobal(dns_compress_t *cctx, const dns_name_t *name,
 140                         dns_name_t *prefix, isc_uint16_t *offset);
 141 /*
 142  *      Finds longest possible match of 'name' in the global compression table.
 143  *
 144  *      Requires:
 145  *              'cctx' to be initialized.
 146  *              'name' to be a absolute name.
 147  *              'prefix' to be initialized.
 148  *              'offset' to point to an isc_uint16_t.
 149  *
 150  *      Ensures:
 151  *              'prefix' and 'offset' are valid if ISC_TRUE is  returned.
 152  *
 153  *      Returns:
 154  *              ISC_TRUE / ISC_FALSE
 155  */
 156
 157 void
 158 dns_compress_add(dns_compress_t *cctx, const dns_name_t *name,
 159                  const dns_name_t *prefix, isc_uint16_t offset);
 160 /*
 161  *      Add compression pointers for 'name' to the compression table,
 162  *      not replacing existing pointers.
 163  *
 164  *      Requires:
 165  *              'cctx' initialized
 166  *
 167  *              'name' must be initialized and absolute, and must remain
 168  *              valid until the message compression is complete.
 169  *
 170  *              'prefix' must be a prefix returned by
 171  *              dns_compress_findglobal(), or the same as 'name'.
 172  */
 173
 174 void
 175 dns_compress_rollback(dns_compress_t *cctx, isc_uint16_t offset);
 176
 177 /*
 178  *      Remove any compression pointers from global table >= offset.
 179  *
 180  *      Requires:
 181  *              'cctx' is initialized.
 182  */
 183
 184 void
 185 dns_decompress_init(dns_decompress_t *dctx, int edns,
 186                     dns_decompresstype_t type);
 187
 188 /*
 189  *      Initializes 'dctx'.
 190  *      Records 'edns' and 'type' into the structure.
 191  *
 192  *      Requires:
 193  *              'dctx' to be a valid pointer.
 194  */
 195
 196 void
 197 dns_decompress_invalidate(dns_decompress_t *dctx);
 198
 199 /*
 200  *      Invalidates 'dctx'.
 201  *
 202  *      Requires:
 203  *              'dctx' to be initialized
 204  */
 205
 206 void
 207 dns_decompress_setmethods(dns_decompress_t *dctx, unsigned int allowed);
 208
 209 /*
 210  *      Sets 'dctx->allowed' to 'allowed'.
 211  *
 212  *      Requires:
 213  *              'dctx' to be initialized
 214  */
 215
 216 unsigned int
 217 dns_decompress_getmethods(dns_decompress_t *dctx);
 218
 219 /*
 220  *      Returns 'dctx->allowed'
 221  *
 222  *      Requires:
 223  *              'dctx' to be initialized
 224  */
 225
 226 int
 227 dns_decompress_edns(dns_decompress_t *dctx);
 228
 229 /*
 230  *      Returns 'dctx->edns'
 231  *
 232  *      Requires:
 233  *              'dctx' to be initialized
 234  */
 235
 236 dns_decompresstype_t
 237 dns_decompress_type(dns_decompress_t *dctx);
 238
 239 /*
 240  *      Returns 'dctx->type'
 241  *
 242  *      Requires:
 243  *              'dctx' to be initialized
 244  */
 245
 246 ISC_LANG_ENDDECLS
 247
 248 #endif /* DNS_COMPRESS_H */