Remove domain extension

Question

So let\'s say I have just-a.domain.com,just-a-domain.info,just.a-domain.net how can I remove the extension .com,.net.info ... and I need the result

Answer 1

If you want to remove the part of the domain that is administrated by domain name registrars, you will need to use a list of such suffixes like the Public Suffix List.

But since a walk through this list and testing the suffix on the domain name is not that efficient, rather use this list only to build an index like this:

$tlds = array(
    // ac : http://en.wikipedia.org/wiki/.ac
    'ac',
    'com.ac',
    'edu.ac',
    'gov.ac',
    'net.ac',
    'mil.ac',
    'org.ac',
    // ad : http://en.wikipedia.org/wiki/.ad
    'ad',
    'nom.ad',
    // …
);
$tldIndex = array_flip($tlds);

Searching for the best match would then go like this:

$levels = explode('.', $domain);
for ($length=1, $n=count($levels); $length<=$n; ++$length) {
    $suffix = implode('.', array_slice($levels, -$length));
    if (!isset($tldIndex[$suffix])) {
        $length--;
        break;
    }
}
$suffix = implode('.', array_slice($levels, -$length));
$prefix = substr($domain, 0, -strlen($suffix) - 1);

Or build a tree that represents the hierarchy of the domain name levels as follows:

$tldTree = array(
    // ac : http://en.wikipedia.org/wiki/.ac
    'ac' => array(
        'com' => true,
        'edu' => true,
        'gov' => true,
        'net' => true,
        'mil' => true,
        'org' => true,
     ),
     // ad : http://en.wikipedia.org/wiki/.ad
     'ad' => array(
        'nom' => true,
     ),
     // …
);

Then you can use the following to find the match:

$levels = explode('.', $domain);
$r = &$tldTree;
$length = 0;
foreach (array_reverse($levels) as $level) {
    if (isset($r[$level])) {
        $r = &$r[$level];
        $length++;
    } else {
        break;
    }
}
$suffix = implode('.', array_slice($levels, - $length));
$prefix = substr($domain, 0, -strlen($suffix) - 1);