gistfile1.txt

int getDefaultAddr(char * addr, size_t addrlen) {
    const char* google_dns_server = "8.8.8.8";
    int dns_port = 53;
  
    struct sockaddr_in serv;
 
    int sock = socket ( AF_INET, SOCK_DGRAM, 0);
  
    if(sock < 0) {
        perror("Socket error");
        return 0;
    }
    
    memset( &serv, 0, sizeof(serv) );
    serv.sin_family = AF_INET;
    serv.sin_addr.s_addr = inet_addr( google_dns_server );
    serv.sin_port = htons( dns_port );

    int err = connect( sock , (const struct sockaddr*) &serv , sizeof(serv) );
    if (err) {
    	    perror("connect");
    	    return 0;
    }
    struct sockaddr_in name;
    socklen_t namelen = sizeof(name);
    err = getsockname(sock, (struct sockaddr*) &name, &namelen);
    if (err) {
    	perror("getsockname");
     	close(sock);
	return 0;
    }
    const char* p = inet_ntop(AF_INET, &name.sin_addr, addr, addrlen);
    if(p != NULL)
	printf("Local ip is : %s \n" , addr);
     else {
     	printf("error parsing host ip\n");
     	close(sock);
	return 0;
     }

    close(sock);
    return 1;
		
}