typedef struct
{
	uint8_t ihl: 4;
	uint8_t v: 4;
	uint8_t tos;
	uint16_t total_len;
	uint16_t id;
	uint16_t off;
	uint8_t ttl;
	uint8_t protocol;
	uint16_t chksum;
	uint32_t srcip;
	uint32_t dstip;
} __attribute__ ((packed)) IPHeader;

typedef struct
{
	uint16_t srcport;
	uint16_t dstport;
	uint16_t len;
	uint16_t chksum;
} __attribute__ ((packed)) UDPHeader;

typedef struct
{
	uint32_t srcip;
	uint32_t dstip;
	uint8_t zero;
	uint8_t protocol;
	uint16_t len;
} __attribute__ ((packed)) PseudoUDPHeader;