util.c

/*
 * File: util.c
 * Author: Andy Sayler
 * Project: CSCI 3753 Programming Assignment 2
 * Create Date: 2012/02/01
 * Modify Date: 2012/02/01
 * Description:
 * 	This file contains declarations of utility functions for
 *      Programming Assignment 2.
 *  
 */

#include "util.h"

int dnslookup(const char* hostname, char* firstIPstr, int maxSize){

    /* Local vars */
    struct addrinfo* headresult = NULL;
    struct addrinfo* result = NULL;
    struct sockaddr_in* ipv4sock = NULL;
    struct in_addr* ipv4addr = NULL;
    char ipv4str[INET_ADDRSTRLEN];
    char ipstr[INET6_ADDRSTRLEN];
    int addrError = 0;

    /* DEBUG: Print Hostname*/
#ifdef UTIL_DEBUG
    fprintf(stderr, "%s\n", hostname);
#endif
   
    /* Lookup Hostname */
    addrError = getaddrinfo(hostname, NULL, NULL, &headresult);
    if(addrError){
	fprintf(stderr, "Error looking up Address: %s\n",
		gai_strerror(addrError));
	return UTIL_FAILURE;
    }
    /* Loop Through result Linked List */
    for(result=headresult; result != NULL; result = result->ai_next){
	/* Extract IP Address and Convert to String */
	if(result->ai_addr->sa_family == AF_INET){
	    /* IPv4 Address Handling */
	    ipv4sock = (struct sockaddr_in*)(result->ai_addr);
	    ipv4addr = &(ipv4sock->sin_addr);
	    if(!inet_ntop(result->ai_family, ipv4addr,
			  ipv4str, sizeof(ipv4str))){
		perror("Error Converting IP to String");
		return UTIL_FAILURE;
	    }
#ifdef UTIL_DEBUG
	    fprintf(stdout, "%s\n", ipv4str);
#endif
	    strncpy(ipstr, ipv4str, sizeof(ipstr));
	    ipstr[sizeof(ipstr)-1] = '\0';
	}
	else if(result->ai_addr->sa_family == AF_INET6){
	    /* IPv6 Handling */
#ifdef UTIL_DEBUG
	    fprintf(stdout, "IPv6 Address: Not Handled\n");
#endif
	    strncpy(ipstr, "UNHANDELED", sizeof(ipstr));
	    ipstr[sizeof(ipstr)-1] = '\0';
	}
	else{
	    /* Unhandlded Protocol Handling */
#ifdef UTIL_DEBUG
	    fprintf(stdout, "Unknown Protocol: Not Handled\n");
#endif
	    strncpy(ipstr, "UNHANDELED", sizeof(ipstr));
	    ipstr[sizeof(ipstr)-1] = '\0';
	}
	/* Save First IP Address */
	if(result==headresult){
	    strncpy(firstIPstr, ipstr, maxSize);
	    firstIPstr[maxSize-1] = '\0';
	}
    }

    /* Cleanup */
    freeaddrinfo(headresult);

    return UTIL_SUCCESS;
}