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PHP code to get the domain name without subdomains (includes the tld, and the special types from IANA). Don't have support for unicode domain names.
<?php
/**
* @param string $domain Pass $_SERVER['SERVER_NAME'] here
* @param bool $debug
*
* @debug bool $debug
* @return string
*/
function get_domain($domain, $debug = false)
{
$original = $domain = strtolower($domain);
if (filter_var($domain, FILTER_VALIDATE_IP)) { return $domain; }
$debug ? print('<strong style="color:green">&raquo;</strong> Parsing: '.$original) : false;
$arr = array_slice(array_filter(explode('.', $domain, 4), function($value){
return $value !== 'www';
}), 0); //rebuild array indexes
if (count($arr) > 2)
{
$count = count($arr);
$_sub = explode('.', $count === 4 ? $arr[3] : $arr[2]);
$debug ? print(" (parts count: {$count})") : false;
if (count($_sub) === 2) // two level TLD
{
$removed = array_shift($arr);
if ($count === 4) // got a subdomain acting as a domain
{
$removed = array_shift($arr);
}
$debug ? print("<br>\n" . '[*] Two level TLD: <strong>' . join('.', $_sub) . '</strong> ') : false;
}
elseif (count($_sub) === 1) // one level TLD
{
$removed = array_shift($arr); //remove the subdomain
if (strlen($_sub[0]) === 2 && $count === 3) // TLD domain must be 2 letters
{
array_unshift($arr, $removed);
}
else
{
// non country TLD according to IANA
$tlds = array(
'aero',
'arpa',
'asia',
'biz',
'cat',
'com',
'coop',
'edu',
'gov',
'info',
'jobs',
'mil',
'mobi',
'museum',
'name',
'net',
'org',
'post',
'pro',
'tel',
'travel',
'xxx',
);
if (count($arr) > 2 && in_array($_sub[0], $tlds) !== false) //special TLD don't have a country
{
array_shift($arr);
}
}
$debug ? print("<br>\n" .'[*] One level TLD: <strong>'.join('.', $_sub).'</strong> ') : false;
}
else // more than 3 levels, something is wrong
{
for ($i = count($_sub); $i > 1; $i--)
{
$removed = array_shift($arr);
}
$debug ? print("<br>\n" . '[*] Three level TLD: <strong>' . join('.', $_sub) . '</strong> ') : false;
}
}
elseif (count($arr) === 2)
{
$arr0 = array_shift($arr);
if (strpos(join('.', $arr), '.') === false
&& in_array($arr[0], array('localhost','test','invalid')) === false) // not a reserved domain
{
$debug ? print("<br>\n" .'Seems invalid domain: <strong>'.join('.', $arr).'</strong> re-adding: <strong>'.$arr0.'</strong> ') : false;
// seems invalid domain, restore it
array_unshift($arr, $arr0);
}
}
$debug ? print("<br>\n".'<strong style="color:gray">&laquo;</strong> Done parsing: <span style="color:red">' . $original . '</span> as <span style="color:blue">'. join('.', $arr) ."</span><br>\n") : false;
return join('.', $arr);
}
$urls = array(
'www.example.com' => 'example.com',
'example.com' => 'example.com',
'example.com.br' => 'example.com.br',
'www.example.com.br' => 'example.com.br',
'www.example.gov.br' => 'example.gov.br',
'localhost' => 'localhost',
'www.localhost' => 'localhost',
'subdomain.localhost' => 'localhost',
'www.subdomain.example.com' => 'example.com',
'subdomain.example.com' => 'example.com',
'subdomain.example.com.br' => 'example.com.br',
'www.subdomain.example.com.br' => 'example.com.br',
'www.subdomain.example.biz.br' => 'example.biz.br',
'subdomain.example.biz.br' => 'example.biz.br',
'subdomain.example.net' => 'example.net',
'www.subdomain.example.net' => 'example.net',
'www.subdomain.example.co.kr' => 'example.co.kr',
'subdomain.example.co.kr' => 'example.co.kr',
'example.co.kr' => 'example.co.kr',
'example.jobs' => 'example.jobs',
'www.example.jobs' => 'example.jobs',
'subdomain.example.jobs' => 'example.jobs',
'insane.subdomain.example.jobs' => 'example.jobs',
'insane.subdomain.example.com.br' => 'example.com.br',
'www.doubleinsane.subdomain.example.com.br' => 'example.com.br',
'www.subdomain.example.jobs' => 'example.jobs',
'test' => 'test',
'www.test' => 'test',
'subdomain.test' => 'test',
'www.detran.sp.gov.br' => 'sp.gov.br',
'www.mp.sp.gov.br' => 'sp.gov.br',
'ny.library.museum' => 'library.museum',
'www.ny.library.museum' => 'library.museum',
'ny.ny.library.museum' => 'library.museum',
'www.library.museum' => 'library.museum',
'info.abril.com.br' => 'abril.com.br',
'127.0.0.1' => '127.0.0.1',
'::1' => '::1',
);
$failed = 0;
$total = count($urls);
foreach ($urls as $from => $expected)
{
$from = get_domain($from, true);
if ($from !== $expected)
{
$failed++;
print("<div style='color:fuchsia;'>expected {$from} to be {$expected}</div>");
}
}
if ($failed)
{
print("{$failed} tests failed out of {$total}");
}
else
{
print("Success");
}
@pocesar

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commented Apr 11, 2013

Codepad code running http://codepad.viper-7.com/GAh1tP

@domyen

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commented Dec 26, 2013

Thank you!

@laimisf

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commented Mar 28, 2014

Thank You! This code helped me a lot ;)

@0xibram

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commented Dec 27, 2014

Thanks!

@neo22s

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commented Feb 18, 2015

Doesn't work for domains with TLD of len = 2:

'dev.example.ca' => 'example.ca',
'dev.example.io' => 'example.io',

Example:
http://codepad.viper-7.com/AB1Hg6

@Titogelo

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commented May 20, 2015

Nice job. Thanks a lot man! :)

@NabiKAZ

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commented Jun 2, 2016

does not work for sub.example.co and return sub.example.co

@pocesar

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commented Aug 8, 2016

the best thing is to create a lookup array with all available TLDs from IANA, a lot have been added since 2013 including having support for punycode https://en.wikipedia.org/wiki/List_of_Internet_top-level_domains a bit of manual setup at first, but performance, and strictly compliant to the list

@codeMonkeyK

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commented Mar 8, 2017

very cool! Saves some custom code writting! Thanks!

@gopalkumar315

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commented Apr 9, 2018

Well written code for finding main domain, thanks...

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