unbound/util/data/packed_rrset.h

/*
 * util/data/packed_rrset.h - data storage for a set of resource records.
 *
 * Copyright (c) 2007, NLnet Labs. All rights reserved.
 *
 * This software is open source.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 * 
 * 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.
 * 
 * Neither the name of the NLNET LABS nor the names of its contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

/**
 * \file
 *
 * This file contains the data storage for RRsets.
 */

#ifndef UTIL_DATA_PACKED_RRSET_H
#define UTIL_DATA_PACKED_RRSET_H
#include "util/storage/lruhash.h"

/** type used to uniquely identify rrsets. Cannot be reused without
 * clearing the cache. */
typedef uint64_t rrset_id_t;

/**
 * This structure contains an RRset. A set of resource records that
 * share the same domain name, type and class.
 *
 * Due to memory management and threading, the key structure cannot be
 * deleted, although the data can be. The id can be set to 0 to store and the
 * structure can be recycled with a new id.
 */
struct packed_rrset_key {
	/** 
	 * entry into hashtable. Note the lock is never destroyed,
	 *  even when this key is retired to the cache. 
	 * the data pointer (if not null) points to a struct packed_rrset.
	 */
	struct lruhash_entry entry;
	/** 
	 * the ID of this rrset. unique, based on threadid + sequenceno. 
	 * ids are not reused, except after flushing the cache.
	 * zero is an unused entry, and never a valid id.
	 * Check this value after getting entry.lock.
	 * The other values in this struct may only be altered after changing
	 * the id (which needs a writelock on entry.lock).
	 */
	rrset_id_t id;

	/**
	 * The domain name. If not null (for id=0) it is allocated, and
	 * contains the wireformat domain name.
	 * This dname is canonicalized.
	 * After the dname uint16_t type and uint16_t class is stored 
	 * in wireformat.
	 */
	uint8_t* dname;
	/** 
	 * Length of the domain name, including last 0 root octet. 
	 * The value+sizeof(uint16_t)*2 is actually allocated. 
	 */
	size_t dname_len;
};

/**
 * RRset data.
 *
 * The data is packed, stored contiguously in memory.
 * memory layout:
 *	o base struct
 *	o rr_data uint8_t* array
 *	o rr_len size_t array
 *	o rr_ttl uint32_t array
 *	o rr_data rdata wireformats
 *	o rrsig_data rdata wireformat
 *
 * Rdata is stored in wireformat. The dname is stored in wireformat.
 * TTLs are stored as absolute values (and could be expired).
 *
 * You need the packed_rrset_key to know dname, type, class of the
 * resource records in this RRset. (if signed the rrsig gives the type too).
 *
 * On the wire an RR is:
 *	name, type, class, ttl, rdlength, rdata.
 * So we need to send the following per RR:
 *	key.dname, ttl, rr_data[i].
 *	since key.dname ends with type and class.
 *	and rr_data starts with the rdlength.
 *	the ttl value to send changes due to time.
 */
struct packed_rrset {
	/** TTL (in seconds like time()) of the rrset */
	uint32_t ttl;
	/** number of rrs. */
	size_t num;
	/** 
	 * Array of pointers to every rr's rdata. 
	 * The rr_data[i] rdata is stored in uncompressed wireformat. 
	 * The first uint16_t of rr_data[i] is network format rdlength.
	 */
	uint8_t** rr_data;
	/** length of every rr's rdata, rr_len[i] is size of rr_data[i]. */
	size_t* rr_len;
	/** TTL of every rr (equal or bigger than the rrset ttl). */
	uint32_t* rr_ttl;
	/** if this rrset is signed with an RRSIG, it is stored here. */
	uint8_t* rrsig_data;
	/** length of rrsig rdata (only examine if rrsig_data is not null) */
	size_t rrsig_len;
};

#endif /* UTIL_DATA_PACKED_RRSET_H */