compress.h revision 8d4bf0c21b742138c9eb3dc2a43e9229f6ce0adc
/*
* Copyright (C) 1999, 2000 Internet Software Consortium.
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM
* DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
* INTERNET SOFTWARE CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
* 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.
*/
/* $Id: compress.h,v 1.26 2001/01/07 22:01:34 gson Exp $ */
#ifndef DNS_COMPRESS_H
#define DNS_COMPRESS_H 1
#include <isc/lang.h>
#include <isc/region.h>
#include <dns/types.h>
ISC_LANG_BEGINDECLS
#define DNS_COMPRESS_NONE 0x00 /* no compression */
#define DNS_COMPRESS_GLOBAL14 0x01 /* "normal" compression. */
#define DNS_COMPRESS_ALL 0x01 /* all compression. */
/*
* Direct manipulation of the structures is strongly discouraged.
*/
#define DNS_COMPRESS_TABLESIZE 64
#define DNS_COMPRESS_INITIALNODES 16
typedef struct dns_compressnode dns_compressnode_t;
struct dns_compressnode {
isc_region_t r;
isc_uint16_t offset;
isc_uint16_t count;
dns_compressnode_t *next;
};
struct dns_compress {
unsigned int magic; /* Magic number. */
unsigned int allowed; /* Allowed methods. */
int edns; /* Edns version or -1. */
/* Global compression table. */
dns_compressnode_t *table[DNS_COMPRESS_TABLESIZE];
/* Preallocated nodes for the table. */
dns_compressnode_t initialnodes[DNS_COMPRESS_INITIALNODES];
isc_uint16_t count; /* Number of nodes. */
isc_mem_t *mctx; /* Memory context. */
};
typedef enum {
DNS_DECOMPRESS_ANY, /* Any compression */
DNS_DECOMPRESS_STRICT, /* Allowed compression */
DNS_DECOMPRESS_NONE /* No compression */
} dns_decompresstype_t;
struct dns_decompress {
unsigned int magic; /* Magic number. */
unsigned int allowed; /* Allowed methods. */
int edns; /* Edns version or -1. */
dns_decompresstype_t type; /* Strict checking */
};
isc_result_t
dns_compress_init(dns_compress_t *cctx, int edns, isc_mem_t *mctx);
/*
* Inialise the compression context structure pointed to by 'cctx'.
*
* Requires:
* 'cctx' is a valid dns_compress_t structure.
* 'mctx' is an initialized memory context.
* Ensures:
* cctx->global is initialized.
*
* Returns:
* ISC_R_SUCCESS
* failures from dns_rbt_create()
*/
void
dns_compress_invalidate(dns_compress_t *cctx);
/*
* Invalidate the compression structure pointed to by cctx.
*
* Requires:
* 'cctx' to be initialized.
*/
void
dns_compress_setmethods(dns_compress_t *cctx, unsigned int allowed);
/*
* Sets allowed compression methods.
*
* Requires:
* 'cctx' to be initialized.
*/
unsigned int
dns_compress_getmethods(dns_compress_t *cctx);
/*
* Gets allowed compression methods.
*
* Requires:
* 'cctx' to be initialized.
*
* Returns:
* allowed compression bitmap.
*/
int
dns_compress_getedns(dns_compress_t *cctx);
/*
* Gets edns value.
*
* Requires:
* 'cctx' to be initialized.
*
* Returns:
* -1 .. 255
*/
isc_boolean_t
dns_compress_findglobal(dns_compress_t *cctx, dns_name_t *name,
dns_name_t *prefix, dns_name_t *suffix,
isc_uint16_t *offset);
/*
* Finds longest possible match of 'name' in the global compression table.
*
* Requires:
* 'cctx' to be initialized.
* 'name' to be a absolute name.
* 'prefix' to be initialized.
* 'suffix' to be initialized.
* 'offset' to point to an isc_uint16_t.
*
* Ensures:
* 'prefix', 'suffix' and 'offset' are valid if ISC_TRUE is
* returned.
*
* Returns:
* ISC_TRUE / ISC_FALSE
*/
void
dns_compress_add(dns_compress_t *cctx, dns_name_t *name, dns_name_t *prefix,
isc_uint16_t offset);
/*
* Add compression pointers for 'name' to the compression table,
* not replacing existing pointers.
*
* Requires:
* 'cctx' initialized
*
* 'name' must be initialized and absolute, and must remain
* valid until the message compression is complete.
*
* 'prefix' must be a prefix returned by
* dns_compress_findglobal(), or the same as 'name'.
*/
void
dns_compress_rollback(dns_compress_t *cctx, isc_uint16_t offset);
/*
* Remove any compression pointers from global table >= offset.
*
* Requires:
* 'cctx' is initialized.
*/
void
dns_decompress_init(dns_decompress_t *dctx, int edns,
dns_decompresstype_t type);
/*
* Initalises 'dctx'.
* Records 'edns' and 'type' into the structure.
*
* Requires:
* 'dctx' to be a valid pointer.
*/
void
dns_decompress_invalidate(dns_decompress_t *dctx);
/*
* Invalidates 'dctx'.
*
* Requires:
* 'dctx' to be initialized
*/
void
dns_decompress_setmethods(dns_decompress_t *dctx, unsigned int allowed);
/*
* Sets 'dctx->allowed' to 'allowed'.
*
* Requires:
* 'dctx' to be initialized
*/
unsigned int
dns_decompress_getmethods(dns_decompress_t *dctx);
/*
* Returns 'dctx->allowed'
*
* Requires:
* 'dctx' to be initialized
*/
int
dns_decompress_edns(dns_decompress_t *dctx);
/*
* Returns 'dctx->edns'
*
* Requires:
* 'dctx' to be initialized
*/
dns_decompresstype_t
dns_decompress_type(dns_decompress_t *dctx);
/*
* Returns 'dctx->type'
*
* Requires:
* 'dctx' to be initialized
*/
ISC_LANG_ENDDECLS
#endif /* DNS_COMPRESS_H */