dns.h

#ifndef DNS_H
#define DNS_H

#include "config.h"

#define DNS_PORT	53
#define MAX_EXT_HDR	8
#define MAX_DNS_ANS_RECORD 	20
#define DELIM	"."
#define T_A 	1
#define T_CNAME	5
#define T_AAAA	28
#define T_PTR 	12

/*
 * The DNS header structure
 */
struct dnshdr {
	uint16_t id;
	uint16_t flags;
	uint16_t qdcount;
	uint16_t ancount;
	uint16_t nscount;
	uint16_t arcount;
} __attribute__((packed));

//DNS header structure
struct DNS_HEADER {
	unsigned short id; // identification number
	unsigned char rd :1; // recursion desired
	unsigned char tc :1; // truncated message
	unsigned char aa :1; // authoritative answer
	unsigned char opcode :4; // purpose of message
	unsigned char qr :1; // query/response flag

	unsigned char rcode :4; // response code
	unsigned char cd :1; // checking disabled
	unsigned char ad :1; // authenticated data
	unsigned char z :1; // its z! reserved
	unsigned char ra :1; // recursion available

	unsigned short q_count; // number of question entries
	unsigned short ans_count; // number of answer entries
	unsigned short auth_count; // number of authority entries
	unsigned short add_count; // number of resource entries
};

#pragma pack(push, 1)
struct R_DATA {
	unsigned short type;
	unsigned short _class;
	unsigned int ttl;
	unsigned short data_len;
};
#pragma pack(pop)

//Pointers to resource record contents
struct RES_RECORD {
	unsigned char *name;
	struct R_DATA *resource;
	unsigned char *rdata;
};

//Constant sized fields of query structure
struct QUESTION {
	unsigned short qtype;
	unsigned short qclass;
};


void *send_dns_queries(void *arg);
void parse_dns_response(unsigned char *data_p);

#endif