getaddrinfo.c

getaddrinfo.c (text/plain), 1.50 KB, created by SpanKY on 2007-11-18 05:13:23 UTC

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

void doit(const char *name, const char *family_name, int family)
{
	printf("--- looking up '%s' for family %s (%i)\n", name, family_name, family);

	struct addrinfo hints;
	memset(&hints, 0, sizeof(hints));
	hints.ai_socktype = SOCK_STREAM;
	hints.ai_flags = AI_NUMERICHOST;
	hints.ai_family = family;

	struct addrinfo *hostaddr = 0;
	int res = getaddrinfo(name, "telnet", &hints, &hostaddr);
	if (res == EAI_NONAME) {
		printf("getaddrinfo(...) = EAI_NONAME, trying again with AI_CANONNAME\n");
		hints.ai_flags = AI_CANONNAME;
		res = getaddrinfo(name, "telnet", &hints, &hostaddr);
	}
	if (res == EAI_NONAME) {
		printf("getaddrinfo(...) = EAI_NONAME ... FAIL\n");
	} else if (res) {
		printf("getaddrinfo(...) = %i ... FAIL\n", res);
	} else {
		printf("getaddrinfo(...) = %i\n", res);

		char name[1024], service[1024];
		res = getnameinfo(hostaddr->ai_addr, hostaddr->ai_addrlen,
			name, sizeof(name), service, sizeof(service),
			NI_NUMERICHOST | NI_NUMERICSERV);
		printf("getnameinfo(...) = %i\n", res);
		printf("\tname = %s\n", name);
		printf("\tservice = %s\n", service);
	}

	freeaddrinfo(hostaddr);
}

int main(int argc, char *argv[])
{
	const char *name = (argc > 1 ? argv[1] : "localhost");

#define doit(name, family) doit(name, #family, family)
	doit(name, 0);
	doit(name, AF_INET);
	doit(name, AF_INET6);

	return 0;
}