getaddrinfo(3) usage

getaddrinfo.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <netdb.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>

#define ADDSZ  (50)

int main(int argc, char **argv)
{
	struct addrinfo hints, *res = NULL, *rp = NULL;
	int getaddrinfoError = 0;
	char addrStrDest[ADDSZ] = {0};
	void *addrStrOrig = NULL;

	if(argc != 3){
		printf("Usage: %s <ADDRESS> <PORT (can be '')\n", argv[0]);
		return(-1);
	}

	memset (&hints, 0, sizeof (hints));
	hints.ai_family = AF_UNSPEC;
	hints.ai_socktype = SOCK_STREAM;
	hints.ai_flags |= AI_CANONNAME;

	getaddrinfoError = getaddrinfo(argv[1], argv[2], &hints, &res);
	if(getaddrinfoError != 0){
		printf("ERRO getaddrinfo(): [%s]\n", gai_strerror(getaddrinfoError));
		return(-1);
	}

	for(rp = res; rp != NULL; rp = rp->ai_next){
		if(rp->ai_family == AF_INET)       addrStrOrig = &((struct sockaddr_in *) rp->ai_addr)->sin_addr;
		else if(rp->ai_family == AF_INET6) addrStrOrig = &((struct sockaddr_in6 *) rp->ai_addr)->sin6_addr;
		else                               addrStrOrig = NULL;

		inet_ntop(rp->ai_family, addrStrOrig, addrStrDest, ADDSZ);
		printf("IPv%d: %s - %s\n", rp->ai_family == AF_INET6 ? 6 : 4, addrStrDest, rp->ai_canonname);
	}

	freeaddrinfo(res);

	return(0);
}

gcc -o getaddrinfo getaddrinfo.c -g -std=c11 -Wall -Wextra -D_XOPEN_SOURCE=700 -D_POSIX_C_SOURCE=200809L -D_POSIX_SOURCE=1 -D_DEFAULT_SOURCE=1 -D_GNU_SOURCE=1