Dual-mode IPv4/IPv6 socket client for Linux

client_ipv4_ipv6.c

// Based on the dual-mode IPv4/IPv6 example in "The Linux Programming Interface", M. Kerrisk, 2010

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <netdb.h>
#include <errno.h>
#include <unistd.h>

#define PORT_NUM "443"

static void print_error(char* extraMessage)
{
    printf("ERROR: %s: %d - %s\n", extraMessage, errno, strerror(errno));
}

static void exit_error(char* extraMessage)
{
    print_error(extraMessage);
    abort();
}

int main(int argc, char **argv)
{
    int ret;
    struct addrinfo hints = {0};
    hints.ai_family = AF_UNSPEC; // Not specified: IPv4 or IPv6.
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_flags = AI_NUMERICSERV;

    if (argc < 2)
    {
        printf("Example usage:\n\tclient <https_host_name>\n");
        return 1;
    }

    struct addrinfo *name_resolution_result;
    if (0 != getaddrinfo(argv[1], PORT_NUM, &hints, &name_resolution_result))
    {
        exit_error("getaddrinfo failed");
    }

    struct addrinfo *rec;
    for (rec = name_resolution_result; rec != NULL; rec = rec->ai_next)
    {
        char host_name[255];
        if (0 != getnameinfo(rec->ai_addr, rec->ai_addrlen, host_name, sizeof(host_name), NULL, 0, NI_NUMERICHOST))
        {
            print_error("getnameinfo failed");
            continue;
        }

        printf("Server Address: \t IPv%d: \t %s\n", rec->ai_family == AF_INET6 ? 6 : 4, host_name);

        int socket_fd = socket(rec->ai_family, rec->ai_socktype, rec->ai_protocol);
        if (socket_fd == -1)
        {
            print_error("socket failed");
            continue;
        }

        if (0 != connect(socket_fd, rec->ai_addr, rec->ai_addrlen))
        {
            print_error("connect failed");
        }
        else
        {
            printf("\tCONNECTED!\n");
        }

        close(socket_fd);
    }


    freeaddrinfo(name_resolution_result);
    return 0;
}

gcc client_ipv4_ipv6.c && ./a.out www.bing.com
Server Address:          IPv6:   2620:1ec:cxx::x00
        CONNECTED!
Server Address:          IPv4:   13.1xx.xx.xx0
        CONNECTED!
Server Address:          IPv4:   204.7x.x1x.xx0
        CONNECTED!