ipv6.c

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <inttypes.h>
#include <arpa/inet.h>

typedef uint32_t			ipv4_addr_t;
typedef struct ipv6_addr_s	ipv6_addr_t;
typedef union ipx_addr_s	ipx_addr_t;

struct ipv6_addr_s {
	union {
		uint64_t u64[2];
		uint32_t u32[4];
		uint16_t u16[8];
		uint8_t  u8[16];
	} u;
} __attribute__ ((__packed__));


union ipx_addr_s {
	struct {
		uint64_t	unused0;
		uint32_t	unused1;
		ipv4_addr_t ip;
	};
	ipv6_addr_t		ip6;
} __attribute__ ((__packed__));


int main(int argc, char **argv)
{
	ipv4_addr_t v4;
	ipv6_addr_t v6;
	char buf[INET6_ADDRSTRLEN];
	ipx_addr_t  *addr;

	addr = (ipx_addr_t *)malloc(sizeof(ipx_addr_t));

	if (inet_pton(AF_INET6, argv[1], &addr->ip6) != 1) {
		printf("ERROR: Invalid IP: %s\n", argv[1]);
	}
	if (inet_ntop(AF_INET6, &addr->ip6, buf, INET6_ADDRSTRLEN) == NULL) {
		printf("ERROR: %s\n", strerror(errno));
	}

	printf("IP address : %s\n", buf);

	return 0;
}