PHP Domain Availability Lookup

• Posted: August 24, 2008
• |
• Author: Regan Johnson
• |
• Filed under: PHP & MySQL, Programming, Tutorials
• |
• Tags: classes, domain, object oriented programming, oop, php, tutorial, whois

The process to check if a domain name is registered or not usually involves a series of steps that can be tedious and time consuming. In this article, I will show you how to create your own domain name availability script using PHP that you may use in your personal projects – it’s much easier than you might think.

Building the Domain Name Availability class

For the sake of this article, let’s call this class “whois”.

class whois {

}

One of the first things we are going to add to our class is a list of the common TLD, which will include which whois server to use for each domain, and the associated text to search for if a domain is available or not. The array is named “$ext” which is short for extensions.

public $ext = array(
'.com' => array('whois.crsnic.net','No match for'),
'.net' => array('whois.crsnic.net','No match for'),
'.org' => array('whois.publicinterestregistry.net','NOT FOUND'),
'.us' => array('whois.nic.us','Not Found'),
'.biz' => array('whois.biz','Not found'),
'.info' => array('whois.afilias.net','NOT FOUND'),
'.eu' => array('whois.eurid.eu','FREE'),
'.mobi' => array('whois.dotmobiregistry.net', 'NOT FOUND'),
'.tv' => array('whois.nic.tv', 'No match for'),
'.in' => array('whois.inregistry.net', 'NOT FOUND'),
'.co.uk' => array('whois.nic.uk','No match'),
'.co.ug' => array('wawa.eahd.or.ug','No entries found'),
'.or.ug' => array('wawa.eahd.or.ug','No entries found'),
'.sg' => array('whois.nic.net.sg','NOMATCH'),
'.com.sg' => array('whois.nic.net.sg','NOMATCH'),
'.per.sg' => array('whois.nic.net.sg','NOMATCH'),
'.org.sg' => array('whois.nic.net.sg','NOMATCH'),
'.com.my' => array('whois.mynic.net.my','does not Exist in database'),
'.net.my' => array('whois.mynic.net.my','does not Exist in database'),
'.org.my' => array('whois.mynic.net.my','does not Exist in database'),
'.edu.my' => array('whois.mynic.net.my','does not Exist in database'),
'.my' => array('whois.mynic.net.my','does not Exist in database'),
'.nl' => array('whois.domain-registry.nl','not a registered domain'),
'.ro' => array('whois.rotld.ro','No entries found for the selected'),
'.com.au' => array('whois.ausregistry.net.au','No data Found'),
'.ca' => array('whois.cira.ca', 'AVAIL'),
'.org.uk' => array('whois.nic.uk','No match'),
'.name' => array('whois.nic.name','No match'),
'.ac.ug' => array('wawa.eahd.or.ug','No entries found'),
'.ne.ug' => array('wawa.eahd.or.ug','No entries found'),
'.sc.ug' => array('wawa.eahd.or.ug','No entries found'),
'.ws' => array('whois.website.ws','No Match'),
'.be' => array('whois.ripe.net','No entries'),
'.com.cn' => array('whois.cnnic.cn','no matching record'),
'.net.cn' => array('whois.cnnic.cn','no matching record'),
'.org.cn' => array('whois.cnnic.cn','no matching record'),
'.no' => array('whois.norid.no','no matches'),
'.se' => array('whois.nic-se.se','No data found'),
'.nu' => array('whois.nic.nu','NO MATCH for'),
'.com.tw' => array('whois.twnic.net','No such Domain Name'),
'.net.tw' => array('whois.twnic.net','No such Domain Name'),
'.org.tw' => array('whois.twnic.net','No such Domain Name'),
'.cc' => array('whois.nic.cc','No match'),
'.nl' => array('whois.domain-registry.nl','is free'),
'.pl' => array('whois.dns.pl','No information about'),
'.pt' => array('whois.dns.pt','No match')
);

We will also define our error variable that we will be using in this class.

public $error;

Building the Methods

Now that we have our class ready to go, and our list of domain name extensions and associated WHOIS servers, lets build the function to use this information to perform the domain name lookup.

function available($domain){
$domain = trim($domain);
if (eregi('^([a-zA-Z0-9]([a-zA-Z0-9\-]{0,61}[a-zA-Z0-9])?\.)*[a-zA-Z0-9]([a-zA-Z0-9\-]{0,61}[a-zA-Z0-9])?$',$domain) != 1){
$error = 'Invalid domain (Letters, numbers and hypens only) ('.$domain.')';
return false;
}
preg_match('@^(http://www\.|http://|www\.)?([^/]+)@i', $domain, $preg_metch_result);
$f_result = '';
$domain = $preg_metch_result[2];
$domain_name_array = explode('.', $domain);
$domain_domain = strtolower(trim($domain_name_array[count($domain_name_array)-1]));
$ext_in_list = false;

if (array_key_exists('.'.$domain_domain, $this->ext)){
$ext_in_list = true;
}

if(strlen($domain) > 0 && $ext_in_list){
$server = '';

$server = $this->ext['.' .$domain_domain][0];
$lookup_result = gethostbyname($server);

if ($lookup_result == $server){
$error = 'Error: Invalid extension - '.$domain_domain.'. / server has outgoing connections blocked to '.$server.'.';
return false;
}

$fs = fsockopen($server, 43,$errno,$errstr,10);
if (!$fs || ($errstr != "")){
$error = 'Error: ('.$server.') '.$errstr.' ('.$errno.')';
return false;
}

fputs($fs, "$domain\r\n");
while( !feof($fs) ) {
$f_result .= fgets($fs,128);
}

fclose($fs);

if($domain_domain == 'org'){
nl2br($f_result);
}

if(eregi($this->ext['.'.$domain_domain][1], $f_result)){
return true;
} else {
return false;
}

} else {
$error = 'Invalid Domain and/or TLD server entry does not exist';
}
return false;
}

Going through the method

I will explain each piece of this method in case you would like to know exactly what is going on.

  $domain = trim($domain);
if (eregi('^([a-zA-Z0-9]([a-zA-Z0-9\-]{0,61}[a-zA-Z0-9])?\.)*[a-zA-Z0-9]([a-zA-Z0-9\-]{0,61}[a-zA-Z0-9])?$',$domain) != 1){
$error = 'Invalid domain (Letters, numbers and hypens only) ('.$domain.')';
return false;
}

Here we are trimming excess whitespace from the domain, and checking to make sure that it conforms to standards. (Checking if the domain is in a valid format). If it is invalid, we give an error, and return false.

  preg_match('@^(http://www\.|http://|www\.)?([^/]+)@i', $domain, $preg_metch_result);
$f_result = '';
$domain = $preg_metch_result[2];
$domain_name_array = explode('.', $domain);
$domain_domain = strtolower(trim($domain_name_array[count($domain_name_array)-1]));
$ext_in_list = false;

if (array_key_exists('.'.$domain_domain, $this->ext)){
$ext_in_list = true;
}

In this block of code, we are splitting the domain name into it’s respective parts (domain, extension) and checking to see that the extension (TLD) is in the list that we defined earlier. We set a variable “$ext_in_list” to true if it is.

  if(strlen($domain) > 0 && $ext_in_list){

We make sure that the extension is in the list, and the domain is at least 1 character long.

  $server = '';
$server = $this->ext['.' .$domain_domain][0];
$lookup_result = gethostbyname($server);

if ($lookup_result == $server){
$error = 'Error: Invalid extension - '.$domain_domain.'. / server has outgoing connections blocked to '.$server.'.';
return false;
}

In this block of code, we get the corresponding WHOIS server from our predefined list, and get the IP address associated with that server. If the result of the IP lookup is false, we assume that the server is blocking our connection or that the extension is invalid. If not, we assume the lookup was successful and valid.

  $fs = fsockopen($server, 43,$errno,$errstr,10);
if (!$fs || ($errstr != "")){
$error = 'Error: ('.$server.') '.$errstr.' ('.$errno.')';
return false;
}

fputs($fs, "$domain\r\n");
while( !feof($fs) ) {
$f_result .= fgets($fs,128);
}

fclose($fs);

if($domain_domain == 'org'){
nl2br($f_result);
}

Here we open a new socket connection on port 43. If the connection fails, we handle the error, and return the method false. If it succeeds, we continue to retrieve result from the socket connection. Once the result is retrieve, we close the connection, and preform some formatting on the results should the domain name be a “.org”.

  if(eregi($this->ext['.'.$domain_domain][1], $f_result)){
return true;
} else {
return false;
}

} else {
$error = 'Invalid Domain and/or TLD server entry does not exist';
}
return false;
}

The last block of code will check our extension array defined earlier to see if the result matches the text provided for that specified extension. If the there is a match, we return true, otherwise, we return false.

Putting it all together

Now that we know how the class and method works, lets put it all together, and give an example on how to use it in your script.

class whois {

public $ext = array(
'.com' => array('whois.crsnic.net','No match for'),
'.net' => array('whois.crsnic.net','No match for'),
'.org' => array('whois.publicinterestregistry.net','NOT FOUND'),
'.us' => array('whois.nic.us','Not Found'),
'.biz' => array('whois.biz','Not found'),
'.info' => array('whois.afilias.net','NOT FOUND'),
'.eu' => array('whois.eurid.eu','FREE'),
'.mobi' => array('whois.dotmobiregistry.net', 'NOT FOUND'),
'.tv' => array('whois.nic.tv', 'No match for'),
'.in' => array('whois.inregistry.net', 'NOT FOUND'),
'.co.uk' => array('whois.nic.uk','No match'),
'.co.ug' => array('wawa.eahd.or.ug','No entries found'),
'.or.ug' => array('wawa.eahd.or.ug','No entries found'),
'.sg' => array('whois.nic.net.sg','NOMATCH'),
'.com.sg' => array('whois.nic.net.sg','NOMATCH'),
'.per.sg' => array('whois.nic.net.sg','NOMATCH'),
'.org.sg' => array('whois.nic.net.sg','NOMATCH'),
'.com.my' => array('whois.mynic.net.my','does not Exist in database'),
'.net.my' => array('whois.mynic.net.my','does not Exist in database'),
'.org.my' => array('whois.mynic.net.my','does not Exist in database'),
'.edu.my' => array('whois.mynic.net.my','does not Exist in database'),
'.my' => array('whois.mynic.net.my','does not Exist in database'),
'.nl' => array('whois.domain-registry.nl','not a registered domain'),
'.ro' => array('whois.rotld.ro','No entries found for the selected'),
'.com.au' => array('whois.ausregistry.net.au','No data Found'),
'.ca' => array('whois.cira.ca', 'AVAIL'),
'.org.uk' => array('whois.nic.uk','No match'),
'.name' => array('whois.nic.name','No match'),
'.ac.ug' => array('wawa.eahd.or.ug','No entries found'),
'.ne.ug' => array('wawa.eahd.or.ug','No entries found'),
'.sc.ug' => array('wawa.eahd.or.ug','No entries found'),
'.ws' => array('whois.website.ws','No Match'),
'.be' => array('whois.ripe.net','No entries'),
'.com.cn' => array('whois.cnnic.cn','no matching record'),
'.net.cn' => array('whois.cnnic.cn','no matching record'),
'.org.cn' => array('whois.cnnic.cn','no matching record'),
'.no' => array('whois.norid.no','no matches'),
'.se' => array('whois.nic-se.se','No data found'),
'.nu' => array('whois.nic.nu','NO MATCH for'),
'.com.tw' => array('whois.twnic.net','No such Domain Name'),
'.net.tw' => array('whois.twnic.net','No such Domain Name'),
'.org.tw' => array('whois.twnic.net','No such Domain Name'),
'.cc' => array('whois.nic.cc','No match'),
'.nl' => array('whois.domain-registry.nl','is free'),
'.pl' => array('whois.dns.pl','No information about'),
'.pt' => array('whois.dns.pt','No match')
);

public $error;

function available($domain){
$domain = trim($domain);
if (eregi('^([a-zA-Z0-9]([a-zA-Z0-9\-]{0,61}[a-zA-Z0-9])?\.)*[a-zA-Z0-9]([a-zA-Z0-9\-]{0,61}[a-zA-Z0-9])?$',$domain) != 1){
$error = 'Invalid domain (Letters, numbers and hypens only) ('.$domain.')';
return false;
}
preg_match('@^(http://www\.|http://|www\.)?([^/]+)@i', $domain, $preg_metch_result);
$f_result = '';
$domain = $preg_metch_result[2];
$domain_name_array = explode('.', $domain);
$domain_domain = strtolower(trim($domain_name_array[count($domain_name_array)-1]));
$ext_in_list = false;

if (array_key_exists('.'.$domain_domain, $this->ext)){
$ext_in_list = true;
}

if(strlen($domain) > 0 && $ext_in_list){
$server = '';
$server = $this->ext['.' .$domain_domain][0];
$lookup_result = gethostbyname($server);

if ($lookup_result == $server){
$error = 'Error: Invalid extension - '.$domain_domain.'. / server has outgoing connections blocked to '.$server.'.';
return false;
}

$fs = fsockopen($server, 43,$errno,$errstr,10);

if (!$fs || ($errstr != "")){
$error = 'Error: ('.$server.') '.$errstr.' ('.$errno.')';
return false;
}

fputs($fs, "$domain\r\n");
while( !feof($fs) ) {
$f_result .= fgets($fs,128);
}

fclose($fs);

if($domain_domain == 'org'){
nl2br($f_result);
}

if(eregi($this->ext['.'.$domain_domain][1], $f_result)){
return true;
} else {
return false;
}

} else {
$error = 'Invalid Domain and/or TLD server entry does not exist';
}
return false;
}

}

Using the Domain Availability class

The use of this class is very straight forward. We first initialize a new instance of our WHOIS class, and then pass the domain name through our availability method.

$domain = 'soaptray.com';

$whois = new whois;
$result = $whois->available($domain);

switch($result){
case true: echo 'Domain is available'; break;
case false: echo 'Domain is already registered'; break;
}

There you have it! Let me know if you find a good use for this class in one of your projects! Good luck and happy coding.

Download this class

The working PHP file for this article can be downloaded here.

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