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

#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <netdb.h>


char *ip_h2s(const char *h, char *s)
{
        struct sockaddr_in addr;

        memset(&addr, 0, sizeof(addr));
        addr.sin_addr.s_addr = htonl(strtoul(h, NULL, 16));
        strcpy(s, inet_ntoa(addr.sin_addr));
        return s;
}


char *ip_h2s_simple(const char *h, char *s)
{
        unsigned int n[4];

        sscanf(h, "%02x%02x%02x%02x", &n[0], &n[1], &n[2], &n[3]);
        sprintf(s, "%d.%d.%d.%d", n[0], n[1], n[2], n[3]);
        return s;
}

int main(int argc, char *argv[])
{
        char s[16];

        printf("%s\n", ip_h2s("C0A80101", s));
        printf("%s\n", ip_h2s_simple("C0A80101", s));

        return 0;
}