PHP whois client function

abstract

compatible

Whois protocol (defined by RFC 3912) is probably one of the simplest internet protocols.

In fact, whois client should open TCP connection to port 43, send query, send CR-LF ("\r\n" constant) and then receive response. Here is the source code:

<?php 
function ae_whois($query, $server)
{

    define('AE_WHOIS_TIMEOUT', 15); // connection timeout
    global $ae_whois_errno, $ae_whois_errstr;

    // connecting 
    $f = fsockopen($server, 43, $ae_whois_errno, $ae_whois_errstr, AE_WHOIS_TIMEOUT);
    if (!$f) 
        return false; // connection failed 

    // sending query    
    fwrite($f, $query."\r\n");

    // receving response 
    $response = '';
    while (!feof($f))
        $response .= fgets($f, 1024);

    // closing connection 
    fclose($f);

    return $response;
}
?>

As you can see, function takes two arguments: whois query and whois server. Function returns server response (if everything was fine), or 'false' constant(that means connection failed). fsockopen error code and error string are written to global variables $ae_whois_errno and $ae_whois_errstr.

You can also change connection timeout by modifying AE_WHOIS_TIMEOUT constant.

Usage example: getting information about domain 'iphone.com'

<?php 

// copy-paste function ae_whois(see above) here 

echo ae_whois('iphone.com', 'whois.verisign-grs.com');
?>

whois.verisign-grs.com is a whois server for .com domains (as of september 2007)

tested