main.c

// Modified from http://www.binarytides.com/hostname-to-ip-address-c-sockets-linux/
#include<stdio.h> //printf
#include<string.h> //memset
#include<stdlib.h> //for exit(0);
#include<sys/socket.h>
#include<errno.h> //For errno - the error number
#include<netdb.h> //hostent
#include<arpa/inet.h>

int hostname_to_ip(char *  , char *);

int main(int argc , char *argv[])
{
   if(argc < 2) {
        printf("please supply destination. eg. http://google.com\n");
        return 1;
   }

    printf("site: %s\n",argv[1]);

    char *hostname = argv[1];
    char ip[100];

    hostname_to_ip(hostname , ip);

    printf("resolved to %s", ip);

    printf("\n");
}

/*
    Get ip from domain name
*/
int hostname_to_ip(char *hostname , char *ip)
{
    int sockfd;
    struct addrinfo hints, *servinfo, *p;
    struct sockaddr_in *h;
    int rv;
    memset(&hints, 0, sizeof hints);
    hints.ai_family = AF_UNSPEC; // use AF_INET6 to force IPv6
    hints.ai_socktype = SOCK_STREAM;

    if ((rv = getaddrinfo( hostname , "http" , &hints , &servinfo)) != 0)
    {
        fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
        return 1;
    }

    // loop through all the results and connect to the first we can
    for (p = servinfo; p != NULL; p = p->ai_next)
    {
        h = (struct sockaddr_in *) p->ai_addr;

        strcat(ip, " ");
        strcat(ip , inet_ntoa( h->sin_addr ) );
        strcat(ip, " ");
    }

    freeaddrinfo(servinfo); // all done with this structure
    return 0;
}