function getipv4fromdns($hostname)
{
//Make sure hostname is not empty
if ($hostname != "") {
//Get DNS Servers
$dns_servers = dns_servers();
//Get DNS suffixes
$suffix = dns_suffix();
//Make sure DNS server list and suffix list are not empty
if (!empty($dns_servers)) {
if (!empty($suffix)) {
//Explode DNS suffixes
$suffix_array = explode(',', $suffix);
//Build array for hostnames with every suffix and without suffix
foreach ($suffix_array as $suffix) {
$hostname_array .= $hostname . $suffix . ",";
}
}
$hostname_array .= $hostname;
//Explode DNS Servers
$dns_servers_array = explode(',', $dns_servers);
//NET DNS2 Resolver with 1 second timeout (default = 5)
$r = new Net_DNS2_Resolver(array('nameservers' => $dns_servers_array));
$r->timeout = "1";
//Loop thru array to make sure every hostname+suffix combination from the array is checked against every DNS Server until (hopefully) a valid response was received
$success = false;
$hostname_array = explode(',', $hostname_array);
foreach ($hostname_array as $hostname) {
//Try DNS query and catch exceptions from NET_DNS2
$ipv4 = "";
try {
$result = $r->query($hostname);
$success = true;
break;
} catch (Net_DNS2_Exception $e) {
$ipv4[0] = "DNS Verification failed! Error: " . $e->getMessage();
}
}
// Loop thru result array to get IP Addresses from result when DNS query succeded
if ($success) {
foreach ($result->answer as $rr) {
if ($rr->type == 'A' && $r->isIPv4($rr->address)) {
$ipv4 = $rr->address . "," . $ipv4;
}
}
//Trim whitespaces and commas
$ipv4 = trim($ipv4);
$ipv4 = rtrim($ipv4, ",");
//Sort IP Addresses
$ipv4_array = explode(',', $ipv4);
natsort($ipv4_array);
$ipv4 = implode(', ', $ipv4_array);
//Trim whitespaces and commas again
$ipv4 = trim($ipv4);
$ipv4 = rtrim($ipv4, ",");
} else {
$ipv4[0] = "Error! Hostname is empty, unreadable or unresolveable!";
//Give back an error due to hostname error
}
} else {
$ipv4[0] = "Error! No DNS Servers specified under settings!";
//Give back an error due to missing dns server setting
}
} else {
$ipv4[0] = "Error! Hostname is empty, unreadable or unresolveable!";
//Give back an error due to hostname error
}
return $ipv4;
}
