test getaddrinfo

test_getaddrinfo.c

#include <stdlib.h>
#include <netdb.h>
#include <netinet/in.h>
#include <stdio.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <assert.h>

#ifndef NI_MAXHOST
#define NI_MAXHOST 1025
#endif

int main(int argc, char* argv[])
{
    struct addrinfo* result;
    struct addrinfo* res;
    int error;

    if (argc < 2) {
        return -1;
    }

    /* resolve the domain name into a list of addresses */
    error = getaddrinfo(argv[1], NULL, NULL, &result);
    if (error != 0) {
        if (error == EAI_SYSTEM) {
            perror("getaddrinfo");
        } else {
            fprintf(stderr, "error in getaddrinfo: %s\n", gai_strerror(error));
        }
        exit(EXIT_FAILURE);
    }

    /* loop over all returned results and do inverse lookup */
    for (res = result; res != NULL; res = res->ai_next) {
        char hostname[NI_MAXHOST] = { 0 };
        char _address[INET6_ADDRSTRLEN] = { 0 };
        error = getnameinfo(res->ai_addr, res->ai_addrlen, hostname, NI_MAXHOST, NULL, 0, 0);
        if (error != 0) {
            fprintf(stderr, "error in getnameinfo: %s\n", gai_strerror(error));
            continue;
        }
        if (res->ai_family == AF_INET) {
            inet_ntop(res->ai_family, &((struct sockaddr_in*)res->ai_addr)->sin_addr, _address, sizeof(_address));
        } else if (res->ai_family == AF_INET6) {
            inet_ntop(res->ai_family, &((struct sockaddr_in6*)res->ai_addr)->sin6_addr, _address, sizeof(_address));
        } else {
            assert(0);
        }

        if (*hostname != '\0') {
            printf("hostname: %s\t%s\n", hostname, _address);
        }
    }

    freeaddrinfo(result);
    return 0;
}