dns.h

/*
 * Copyright (C) 2014 John Crispin <blogic@openwrt.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License version 2.1
 * as published by the Free Software Foundation
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#ifndef _DNS_H__
#define _DNS_H__

#include <stdint.h>
#include <arpa/inet.h>

#define FLAG_RESPONSE		0x8000
#define FLAG_AUTHORATIVE	0x0400

#define TYPE_A			0x0001
#define TYPE_PTR		0x000C
#define TYPE_TXT		0x0010
#define TYPE_AAAA		0x001c
#define TYPE_SRV		0x0021
#define TYPE_ANY		0x00ff

#define IS_COMPRESSED(x)	((x & 0xc0) == 0xc0)

#define MCAST_ADDR		"224.0.0.251"
#define MCAST_ADDR6		"ff02::fb"
#define MCAST_PORT		5353

#define CLASS_FLUSH		0x8000
#define CLASS_UNICAST		0x8000
#define CLASS_IN		0x0001

#define MAX_NAME_LEN		8096
#define MAX_DATA_LEN		8096

#define C_DNS_SD		"_services._dns-sd._udp.local"

struct dns_header {
	uint16_t id;
	uint16_t flags;
	uint16_t questions;
	uint16_t answers;
	uint16_t authority;
	uint16_t additional;
} __attribute__((packed));

struct dns_srv_data {
	uint16_t priority;
	uint16_t weight;
	uint16_t port;
} __attribute__((packed));

struct dns_answer {
	uint16_t type;
	uint16_t class;
	uint32_t ttl;
	uint16_t rdlength;
} __attribute__((packed));

struct dns_question {
	uint16_t type;
	uint16_t class;
} __attribute__((packed));

struct interface;
extern int cfg_proto;
extern int cfg_no_subnet;

void dns_send_question(struct interface *iface, struct sockaddr *to,
		       const char *question, int type, int multicast);
void dns_init_answer(void);
void dns_add_answer(int type, const uint8_t *rdata, uint16_t rdlength, int ttl);
void dns_send_answer(struct interface *iface, struct sockaddr *to, const char *answer);
void dns_reply_a(struct interface *iface, struct sockaddr *to, int ttl, const char *hostname);
void dns_reply_a_additional(struct interface *iface, struct sockaddr *to, int ttl);
const char* dns_type_string(uint16_t type);
void dns_handle_packet(struct interface *iface, struct sockaddr *s, uint16_t port, uint8_t *buf, int len);

#endif