sub get_client_host {
    my $client_ip = shift;
    my ($ip_addr, $client_host);

    $client_ip ne 'empty'
        ?   do {
                $ip_addr = inet_aton($client_ip) || 'N/A';
                $client_host = gethostbyaddr($ip_addr, AF_INET) || 'N/A';
                length($client_host) < 3 && ($client_host = 'N/A');
            }
        :   ($client_host = 'N/A');

    \$client_host;
}