#include <stdlib.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <linux/if_packet.h>
#include <linux/if_ether.h>
#include <sys/ioctl.h>
#include <net/if.h>

#define ICMP_TREQUEST 8
#define ICMP_TECHO    0

#define ICMP_DEFAULT_SIZE 0
//#define ICMP_MAX

typedef struct icmp_pckt_t
{
	//etherenet header - 14 bytes
	uint8_t eth_dest[6];
	uint8_t eth_src[6];
	uint16_t eth_type;

	//IP4 header - 20 bytes
	uint8_t head_hlength; //4bits version, 4bit header length
	uint8_t tos;
	uint16_t ip_length;
	
	uint16_t ip_ident;
	uint16_t flags_fragment_off;
	
	uint8_t ttl; //time to live
	uint8_t protocol;
	uint16_t ip_chksum;

	uint32_t source_addr;
	uint32_t dest_addr;

	//ICMP header 12 bytes
	uint8_t type;
	uint8_t code;
	uint16_t icmp_check_sum;
	uint16_t icmp_ident;
	uint16_t seq_num;
	uint8_t data[ICMP_MAX_DATA];
} __attribute__((packed, aligned(1))) icmp_pckt_t;

int icmp_eth_init( icmp_pckt_t *icmp );
int icmp_eth_dest( icmp_pckt_t *icmp, uint8_t *mac );
int icmp_eth_src( icmp_pckt_t *icmp, uint8_t *mac );
int icmp_eth_len( icmp_pckt_t *icmp );
int icmp_ip_init( icmp_pckt_t *icmp );
int icmp_ip_chksum( icmp_pckt_t *icmp );
int icmp_ip_dest( icmp_pckt_t *icmp, uint32_t dest );
int icmp_ip_src( icmp_pckt_t *icmp, uint32_t src );
int icmp_ip_ident( icmp_pckt_t *icmp, uint16_t ident );
int icmp_ip_ttl( icmp_pckt_t *icmp, uint8_t ttl );
int icmp_ip_len( icmp_pckt_t *icmp );
int icmp_icmp_init( icmp_pckt_t *icmp );
int icmp_icmp_set_chks( icmp_pckt_t *icmp );
int icmp_icmp_set_code( icmp_pckt_t *icmp, uint8_t code );
int icmp_icmp_set_type( icmp_pckt_t *icmp, uint8_t type );
int icmp_icmp_len( icmp_pckt_t *icmp );
int icmp_icmp_ident( icmp_pckt_t *icmp, uint16_t ident );
int icmp_icmp_seq( icmp_pckt_t *icmp, uint16_t seq);
int icmp_total_len( icmp_pckt_t *icmp );
int icmp_icmp_ts( icmp_pckt_t *icmp, uint64_t timestamp );
int icmp_dump( icmp_pckt_t *icmp );
int icmp_data( icmp_pckt_t *icmp, uint8_t *data, size_t size );

uint16_t
ip_checksum (uint16_t *addr, int len);