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Diffstat (limited to 'lib/dns/include/dns/compress.h')
| -rw-r--r-- | lib/dns/include/dns/compress.h | 299 |
1 files changed, 299 insertions, 0 deletions
diff --git a/lib/dns/include/dns/compress.h b/lib/dns/include/dns/compress.h new file mode 100644 index 0000000..5476dd9 --- /dev/null +++ b/lib/dns/include/dns/compress.h @@ -0,0 +1,299 @@ +/* + * Copyright (C) Internet Systems Consortium, Inc. ("ISC") + * + * SPDX-License-Identifier: MPL-2.0 + * + * This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, you can obtain one at https://mozilla.org/MPL/2.0/. + * + * See the COPYRIGHT file distributed with this work for additional + * information regarding copyright ownership. + */ + +#pragma once + +#include <inttypes.h> +#include <stdbool.h> + +#include <isc/lang.h> +#include <isc/region.h> + +#include <dns/name.h> +#include <dns/types.h> + +ISC_LANG_BEGINDECLS + +/*! \file dns/compress.h + * Direct manipulation of the structures is strongly discouraged. + * + * A name compression context handles compression of multiple DNS names + * in relation to a single DNS message. The context can be used to + * selectively turn on/off compression for specific names (depending on + * the RR type) by using \c dns_compress_setmethods(). Alternately, + * compression can be disabled completely using \c + * dns_compress_disable(). + * + * \c dns_compress_setmethods() is intended for use by RDATA towire() + * implementations, whereas \c dns_compress_disable() is intended to be + * used by a nameserver's configuration manager. + */ + +#define DNS_COMPRESS_NONE 0x00 /*%< no compression */ +#define DNS_COMPRESS_GLOBAL14 0x01 /*%< "normal" compression. */ +#define DNS_COMPRESS_ALL 0x01 /*%< all compression. */ +#define DNS_COMPRESS_CASESENSITIVE 0x02 /*%< case sensitive compression. */ +#define DNS_COMPRESS_ENABLED 0x04 + +/* + * DNS_COMPRESS_TABLESIZE must be a power of 2. The compress code + * utilizes this assumption. + */ +#define DNS_COMPRESS_TABLEBITS 6 +#define DNS_COMPRESS_TABLESIZE (1U << DNS_COMPRESS_TABLEBITS) +#define DNS_COMPRESS_TABLEMASK (DNS_COMPRESS_TABLESIZE - 1) +#define DNS_COMPRESS_INITIALNODES 24 +#define DNS_COMPRESS_ARENA_SIZE 640 + +typedef struct dns_compressnode dns_compressnode_t; + +struct dns_compressnode { + dns_compressnode_t *next; + uint16_t offset; + uint16_t count; + isc_region_t r; + dns_name_t name; +}; + +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 arena for names. */ + unsigned char arena[DNS_COMPRESS_ARENA_SIZE]; + off_t arena_off; + /*% Preallocated nodes for the table. */ + dns_compressnode_t initialnodes[DNS_COMPRESS_INITIALNODES]; + 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); +/*%< + * Initialise the compression context structure pointed to by + * 'cctx'. A freshly initialized context has name compression + * enabled, but no methods are set. Please use \c + * dns_compress_setmethods() to set a compression method. + * + * Requires: + * \li 'cctx' is a valid dns_compress_t structure. + * \li 'mctx' is an initialized memory context. + * Ensures: + * \li cctx->global is initialized. + * + * Returns: + * \li #ISC_R_SUCCESS + */ + +void +dns_compress_invalidate(dns_compress_t *cctx); + +/*%< + * Invalidate the compression structure pointed to by cctx. + * + * Requires: + *\li 'cctx' to be initialized. + */ + +void +dns_compress_setmethods(dns_compress_t *cctx, unsigned int allowed); + +/*%< + * Sets allowed compression methods. + * + * Requires: + *\li 'cctx' to be initialized. + */ + +unsigned int +dns_compress_getmethods(dns_compress_t *cctx); + +/*%< + * Gets allowed compression methods. + * + * Requires: + *\li 'cctx' to be initialized. + * + * Returns: + *\li allowed compression bitmap. + */ + +void +dns_compress_disable(dns_compress_t *cctx); +/*%< + * Disables all name compression in the context. Once disabled, + * name compression cannot currently be re-enabled. + * + * Requires: + *\li 'cctx' to be initialized. + * + */ + +void +dns_compress_setsensitive(dns_compress_t *cctx, bool sensitive); + +/* + * Preserve the case of compressed domain names. + * + * Requires: + * 'cctx' to be initialized. + */ + +bool +dns_compress_getsensitive(dns_compress_t *cctx); +/* + * Return whether case is to be preserved when compressing + * domain names. + * + * Requires: + * 'cctx' to be initialized. + */ + +int +dns_compress_getedns(dns_compress_t *cctx); + +/*%< + * Gets edns value. + * + * Requires: + *\li 'cctx' to be initialized. + * + * Returns: + *\li -1 .. 255 + */ + +bool +dns_compress_findglobal(dns_compress_t *cctx, const dns_name_t *name, + dns_name_t *prefix, uint16_t *offset); +/*%< + * Finds longest possible match of 'name' in the global compression table. + * + * Requires: + *\li 'cctx' to be initialized. + *\li 'name' to be a absolute name. + *\li 'prefix' to be initialized. + *\li 'offset' to point to an uint16_t. + * + * Ensures: + *\li 'prefix' and 'offset' are valid if true is returned. + * + * Returns: + *\li #true / #false + */ + +void +dns_compress_add(dns_compress_t *cctx, const dns_name_t *name, + const dns_name_t *prefix, uint16_t offset); +/*%< + * Add compression pointers for 'name' to the compression table, + * not replacing existing pointers. + * + * Requires: + *\li 'cctx' initialized + * + *\li 'name' must be initialized and absolute, and must remain + * valid until the message compression is complete. + * + *\li 'prefix' must be a prefix returned by + * dns_compress_findglobal(), or the same as 'name'. + */ + +void +dns_compress_rollback(dns_compress_t *cctx, uint16_t offset); + +/*%< + * Remove any compression pointers from global table >= offset. + * + * Requires: + *\li 'cctx' is initialized. + */ + +void +dns_decompress_init(dns_decompress_t *dctx, int edns, + dns_decompresstype_t type); + +/*%< + * Initializes 'dctx'. + * Records 'edns' and 'type' into the structure. + * + * Requires: + *\li 'dctx' to be a valid pointer. + */ + +void +dns_decompress_invalidate(dns_decompress_t *dctx); + +/*%< + * Invalidates 'dctx'. + * + * Requires: + *\li 'dctx' to be initialized + */ + +void +dns_decompress_setmethods(dns_decompress_t *dctx, unsigned int allowed); + +/*%< + * Sets 'dctx->allowed' to 'allowed'. + * + * Requires: + *\li 'dctx' to be initialized + */ + +unsigned int +dns_decompress_getmethods(dns_decompress_t *dctx); + +/*%< + * Returns 'dctx->allowed' + * + * Requires: + *\li 'dctx' to be initialized + */ + +int +dns_decompress_edns(dns_decompress_t *dctx); + +/*%< + * Returns 'dctx->edns' + * + * Requires: + *\li 'dctx' to be initialized + */ + +dns_decompresstype_t +dns_decompress_type(dns_decompress_t *dctx); + +/*%< + * Returns 'dctx->type' + * + * Requires: + *\li 'dctx' to be initialized + */ + +ISC_LANG_ENDDECLS |