Remove subdomain from $_SERVER['SERVER_NAME']

Question

I need to make a script where it would remove the subdomain from $_SERVER['SERVER_NAME'] to use it on the domain option of the setcookie function to allow the access of the cookie on all possible subdomains.

For example, let's say I have

function strip_out_subdomain($domain)
{
    //do something to remove subdomain
    return $only_my_domain;
}
$domain = strip_out_subdomain($_SERVER['SERVER_NAME']);
setcookie('mycookie', '123', time()+3600, '/', $domain);

The main problem here is I don't know the pattern for my domain. It could be something like:

• www.mydomain.com
• subdomain.mydomain.com
• subdo.mydo.co
• subdo.subdo.mydomain.com
• subdo.subdo.mydo.co.uk
• etc.

Thank you

Stephanie

Answer 1

This is a regex style of removing sub domain part from the full domain name.

The

.*?

operator makes the wildcard matching to be ungreedy so that it matches the first dot.

function strip_out_subdomain($domain)
{
    $only_my_domain = preg_replace("/^(.*?)\.(.*)$/","$2",$domain);
    return $only_my_domain;
}

Answer 2

Is it possible to define a variable in the server configuration (httpd.conf, .htaccess)? It requires a bit of additional initial administration, but could at least be done in a central location.

I was able to set a variable in Apache

SetEnv MY_DOMAIN mydomain.com

which could be consumed in PHP:

$_SERVER['MY_DOMAIN']

Answer 3

You can query the Alexa service with cURL and extract the hostname without subdomain:

function hostname($domain) {

$querystring = 'http://xml.alexa.com/data?cli=10&dat=nsa&ver=quirk-searchstatus&uid=19700101000000&userip=127.0.0.1&url='.urlencode($domain);
$ch = curl_init();
$user_agent = $_SERVER['HTTP_USER_AGENT'];
curl_setopt ($ch, CURLOPT_URL, $querystring);
curl_setopt ($ch, CURLOPT_USERAGENT, $user_agent);
curl_setopt ($ch, CURLOPT_HEADER, 1);
curl_setopt ($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt ($ch, CURLOPT_FOLLOWLOCATION, 1);
curl_setopt ($ch, CURLOPT_TIMEOUT, 120);
$data= curl_exec($ch);
curl_close($ch);

preg_match('/\<POPULARITY URL="(.*?)" TEXT="(.*?)" SOURCE="(.*?)"\/\>/Ui',$data,$extract);
$hostname = str_replace('/', '', $extract[1]);

return($hostname);
}