imageProxy.php

<?php
/**
 * ownCloud - passman
 *
 * This file is licensed under the Affero General Public License version 3 or
 * later. See the COPYING file.
 *
 * @author Sander Brand <brantje@gmail.com>
 * @copyright Sander Brand 2014
 */
function getURL($url) {
	$ch = curl_init();
	curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
	curl_setopt($ch, CURLOPT_HEADER, 0);
	curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
	curl_setopt($ch, CURLOPT_URL, $url);
	$tmp = curl_exec($ch);
	curl_close($ch);
	$httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
	if ($httpCode == 404) {
		return false;
	} else {
		if ($tmp != false) {
			return $tmp;
		}
	}
}

$url = $_GET['url'];
if (filter_var($url, FILTER_VALIDATE_URL) === FALSE) {
	die('Not a valid URL');
}

$f = getURL($url);
$isIcon = (strpos($url,'.ico')!== false) ? 'ico:' : '';
try{
 	$name = tempnam("/tmp", "imageProxy");
   	file_put_contents($name, $f);

   	$image = new Imagick($isIcon.$name);
	 print_r($image->getformat());
	if($image->valid()){
		$image->setImageFormat('png');
		header("Content-Type: image/png");
		echo $image;
	}
} catch(exception $e){
	echo $e;	
}

?>