getdns/src/mdns.h

/*
* Functions for MDNS resolving.
*/

/*
* Copyright (c) 2016 Christian Huitema <huitema@huitema.net>
*
* 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 THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR 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.
*/

#ifndef MDNS_H
#define MDNS_H

#ifdef HAVE_MDNS_SUPPORT
#include "getdns/getdns.h"
#include "types-internal.h"
#include "util-internal.h"
#include "platform.h"
#include "util/lruhash.h"
#include "config.h"

getdns_return_t
_getdns_submit_mdns_request(getdns_network_req *netreq);

getdns_return_t
_getdns_mdns_namespace_check(getdns_dns_req *dnsreq);

/*
 * data structure for continuous queries
 */

typedef struct getdns_mdns_known_record
{
	/* For storage in context->mdns_known_records_by_value */
	_getdns_rbnode_t node;
	uint64_t insertion_microsec;
	uint16_t record_type;
	uint16_t record_class;
	uint32_t ttl;
	int name_len;
	int record_data_len;
	uint8_t* name;
	uint8_t * record_data;
} getdns_mdns_known_record;

/* 
 * Each entry in the hash table is keyed by type, class and name.
 * The key structure also contains the LRU hash entry structure.
 * The data part contains:
 * - 64 bit time stamp
 * - 32 bit word describing the record size
 * - 32 bit word describing teh allocated memory size
 * - valid DNS response, including 1 query and N answers, 0 AUTH, 0 AD.
 * For economy, the names of all answers are encoded using header compression, pointing
 * to the name in the query, i.e. offset 12 from beginning of message.
 * For stability, the names included in the data part of records are not compressed.
 */

typedef struct getdns_mdns_cached_key_header
{
	/* embedded entry, for LRU hash */
	struct lruhash_entry entry;
	/* identification */
	uint16_t record_type;
	uint16_t record_class;
	int name_len;
	/* the octets following this structure contain the name */
} getdns_mdns_cached_key_header;

typedef struct getdns_mdns_cached_record_header
{
	uint64_t insertion_microsec;
	uint32_t content_len;
	uint32_t allocated_length;
	/* list of user queries */
	getdns_network_req *netreq_first;
} getdns_mdns_cached_record_header;

typedef struct getdns_mdns_continuous_query
{
	/* For storage in context->mdns_continuous_queries_by_name_rrtype */
	_getdns_rbnode_t node;
	uint8_t name[256]; /* binary representation of name being queried */
	int name_len;
	uint16_t request_class;
	uint16_t request_type;
	/* list of user queries */
	getdns_network_req *netreq_first;
	/* todo: do we need an expiration date, or a timer? */
	/* todo: do we need an update mark for showing last results? */
} getdns_mdns_continuous_query;

typedef struct mdns_network_connection
{
	struct getdns_context* context;
	int fd;
	int addr_mcast_len;
	SOCKADDR_STORAGE addr_mcast;
	getdns_eventloop_event  event;
	uint8_t response[1500];
} mdns_network_connection;


void _getdns_mdns_context_init(struct getdns_context *context);
void _getdns_mdns_context_destroy(struct getdns_context *context);

#endif /* HAVE_MDNS_SUPPORT */

#endif /* MDNS_H */