php-regex-favicon.php

<?php
function parseFavicon($html) {
	// Get the 'href' attribute value in a <link rel="icon" ... />
	// Also works for IE style: <link rel="shortcut icon" href="http://www.example.com/myicon.ico" />
	// And for iOS style: <link rel="apple-touch-icon" href="somepath/image.ico">
	$matches = array();

	// Search for <link rel="icon" type="image/png" href="http://example.com/icon.png" />
	preg_match('/<link.*?rel=("|\').*icon("|\').*?href=("|\')(.*?)("|\')/i', $html, $matches);
	if (count($matches) > 4) {
		return trim($matches[4]);
	}

	// Order of attributes could be swapped around: <link type="image/png" href="http://example.com/icon.png" rel="icon" />
	preg_match('/<link.*?href=("|\')(.*?)("|\').*?rel=("|\').*icon("|\')/i', $html, $matches);
	if (count($matches) > 2) {
		return trim($matches[2]);
	}	

	// No match
	return null;
}
?>