- strpos: documentation ( source)
- parse_url: documentation ( source)
<?php
$referer = "http://www.whatever.com/myntra";
$host = parse_url($referer, PHP_URL_HOST);
if (strpos($host, ".google.") !== "false") echo "google";
else if ($host != parse_url(base_url, PHP_URL_HOST)) echo $host;