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util.php

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  • util.php 22.40 KiB
    <?php
    /**
     * Class for utility functions
     *
     */
    
    class OC_Util {
    	public static $scripts=array();
    	public static $styles=array();
    	public static $headers=array();
    	private static $rootMounted=false;
    	private static $fsSetup=false;
    	public static $core_styles=array();
    	public static $core_scripts=array();
    
    	// Can be set up
    	public static function setupFS( $user = '' ) {// configure the initial filesystem based on the configuration
    		if(self::$fsSetup) {//setting up the filesystem twice can only lead to trouble
    			return false;
    		}
    
    		// If we are not forced to load a specific user we load the one that is logged in
    		if( $user == "" && OC_User::isLoggedIn()) {
    			$user = OC_User::getUser();
    		}
    
    		// load all filesystem apps before, so no setup-hook gets lost
    		if(!isset($RUNTIME_NOAPPS) || !$RUNTIME_NOAPPS) {
    			OC_App::loadApps(array('filesystem'));
    		}
    
    		// the filesystem will finish when $user is not empty,
    		// mark fs setup here to avoid doing the setup from loading
    		// OC_Filesystem
    		if ($user != '') {
    			self::$fsSetup=true;
    		}
    
    		$CONFIG_DATADIRECTORY = OC_Config::getValue( "datadirectory", OC::$SERVERROOT."/data" );
    		//first set up the local "root" storage
    		if(!self::$rootMounted) {
    			\OC\Files\Filesystem::mount('\OC\Files\Storage\Local', array('datadir'=>$CONFIG_DATADIRECTORY), '/');
    			self::$rootMounted=true;
    		}
    
    		if( $user != "" ) { //if we aren't logged in, there is no use to set up the filesystem
    			$user_dir = '/'.$user.'/files';
    			$user_root = OC_User::getHome($user);
    			$userdirectory = $user_root . '/files';
    			if( !is_dir( $userdirectory )) {
    				mkdir( $userdirectory, 0755, true );
    			}
    			//jail the user into his "home" directory
    			\OC\Files\Filesystem::init($user_dir);
    
    			$quotaProxy=new OC_FileProxy_Quota();
    			$fileOperationProxy = new OC_FileProxy_FileOperations();
    			OC_FileProxy::register($quotaProxy);
    			OC_FileProxy::register($fileOperationProxy);
    
    			OC_Hook::emit('OC_Filesystem', 'setup', array('user' => $user, 'user_dir' => $user_dir));
    		}
    		return true;
    	}
    
    	public static function tearDownFS() {
    		\OC\Files\Filesystem::tearDown();
    		self::$fsSetup=false;
    	}
    
    	/**
    	 * get the current installed version of ownCloud
    	 * @return array
    	 */
    	public static function getVersion() {
    		// hint: We only can count up. So the internal version number of ownCloud 4.5 will be 4.90.0. This is not visible to the user
    		return array(4, 91, 9);
    	}
    
    	/**
    	 * get the current installed version string of ownCloud
    	 * @return string
    	 */
    	public static function getVersionString() {
    		return '5.0 pre alpha';
    	}
    
    	/**
    	 * get the current installed edition of ownCloud. There is the community edition that just returns an empty string and the enterprise edition that returns "Enterprise".
    	 * @return string
    	 */
    	public static function getEditionString() {
    		return '';
    	}
    
    	/**
    	 * add a javascript file
    	 *
    	 * @param appid  $application
    	 * @param filename  $file
    	 */
    	public static function addScript( $application, $file = null ) {
    		if( is_null( $file )) {
    			$file = $application;
    			$application = "";
    		}
    		if( !empty( $application )) {
    			self::$scripts[] = "$application/js/$file";
    		}else{
    			self::$scripts[] = "js/$file";
    		}
    	}
    
    	/**
    	 * add a css file
    	 *
    	 * @param appid  $application
    	 * @param filename  $file
    	 */
    	public static function addStyle( $application, $file = null ) {
    		if( is_null( $file )) {
    			$file = $application;
    			$application = "";
    		}
    		if( !empty( $application )) {
    			self::$styles[] = "$application/css/$file";
    		}else{
    			self::$styles[] = "css/$file";
    		}
    	}
    
    	/**
    	 * @brief Add a custom element to the header
    	 * @param string tag tag name of the element
    	 * @param array $attributes array of attributes for the element
    	 * @param string $text the text content for the element
    	 */
    	public static function addHeader( $tag, $attributes, $text='') {
    		self::$headers[] = array('tag'=>$tag, 'attributes'=>$attributes, 'text'=>$text);
    	}
    
    	/**
    	 * formats a timestamp in the "right" way
    	 *
    	 * @param int timestamp $timestamp
    	 * @param bool dateOnly option to omit time from the result
    	 */
    	public static function formatDate( $timestamp, $dateOnly=false) {
    		if(isset($_SESSION['timezone'])) {//adjust to clients timezone if we know it
    			$systemTimeZone = intval(date('O'));
    			$systemTimeZone=(round($systemTimeZone/100, 0)*60)+($systemTimeZone%100);
    			$clientTimeZone=$_SESSION['timezone']*60;
    			$offset=$clientTimeZone-$systemTimeZone;
    			$timestamp=$timestamp+$offset*60;
    		}
    		$l=OC_L10N::get('lib');
    		return $l->l($dateOnly ? 'date' : 'datetime', $timestamp);
    	}
    
    	/**
    	 * check if the current server configuration is suitable for ownCloud
    	 * @return array arrays with error messages and hints
    	 */
    	public static function checkServer() {
    		$errors=array();
    
    		$web_server_restart= false;
    		//check for database drivers
    		if(!(is_callable('sqlite_open') or class_exists('SQLite3')) and !is_callable('mysql_connect') and !is_callable('pg_connect')) {
    			$errors[]=array('error'=>'No database drivers (sqlite, mysql, or postgresql) installed.<br/>', 'hint'=>'');//TODO: sane hint
    			$web_server_restart= true;
    		}
    
    		//common hint for all file permissons error messages
    		$permissionsHint="Permissions can usually be fixed by giving the webserver write access to the ownCloud directory";
    
    		// Check if config folder is writable.
    		if(!is_writable(OC::$SERVERROOT."/config/") or !is_readable(OC::$SERVERROOT."/config/")) {
    			$errors[]=array('error'=>"Can't write into config directory 'config'", 'hint'=>"You can usually fix this by giving the webserver user write access to the config directory in owncloud");
    		}
    
    		// Check if there is a writable install folder.
    		if(OC_Config::getValue('appstoreenabled', true)) {
    			if( OC_App::getInstallPath() === null  || !is_writable(OC_App::getInstallPath()) || !is_readable(OC_App::getInstallPath()) ) {
    				$errors[]=array('error'=>"Can't write into apps directory", 'hint'=>"You can usually fix this by giving the webserver user write access to the apps directory
    				in owncloud or disabling the appstore in the config file.");
    			}
    		}
    		$CONFIG_DATADIRECTORY = OC_Config::getValue( "datadirectory", OC::$SERVERROOT."/data" );
    		// Create root dir.
    		if(!is_dir($CONFIG_DATADIRECTORY)) {
    			$success=@mkdir($CONFIG_DATADIRECTORY);
    			if ($success) {
    				$errors = array_merge($errors, self::checkDataDirectoryPermissions($CONFIG_DATADIRECTORY));
    			} else {
    				$errors[]=array('error'=>"Can't create data directory (".$CONFIG_DATADIRECTORY.")", 'hint'=>"You can usually fix this by giving the webserver write access to the ownCloud directory '".OC::$SERVERROOT."' (in a terminal, use the command 'chown -R www-data:www-data /path/to/your/owncloud/install/data' ");
    			}
    		} else if(!is_writable($CONFIG_DATADIRECTORY) or !is_readable($CONFIG_DATADIRECTORY)) {
    			$errors[]=array('error'=>'Data directory ('.$CONFIG_DATADIRECTORY.') not writable by ownCloud<br/>', 'hint'=>$permissionsHint);
    		} else {
    			$errors = array_merge($errors, self::checkDataDirectoryPermissions($CONFIG_DATADIRECTORY));
    		}
    		// check if all required php modules are present
    		if(!class_exists('ZipArchive')) {
    			$errors[]=array('error'=>'PHP module zip not installed.<br/>', 'hint'=>'Please ask your server administrator to install the module.');
    			$web_server_restart= false;
    		}
    
    		if(!function_exists('mb_detect_encoding')) {
    			$errors[]=array('error'=>'PHP module mb multibyte not installed.<br/>', 'hint'=>'Please ask your server administrator to install the module.');
    			$web_server_restart= false;
    		}
    		if(!function_exists('ctype_digit')) {
    			$errors[]=array('error'=>'PHP module ctype is not installed.<br/>', 'hint'=>'Please ask your server administrator to install the module.');
    			$web_server_restart= false;
    		}
    		if(!function_exists('json_encode')) {
    			$errors[]=array('error'=>'PHP module JSON is not installed.<br/>', 'hint'=>'Please ask your server administrator to install the module.');
    			$web_server_restart= false;
    		}
    		if(!function_exists('imagepng')) {
    			$errors[]=array('error'=>'PHP module GD is not installed.<br/>', 'hint'=>'Please ask your server administrator to install the module.');
    			$web_server_restart= false;
    		}
    		if(!function_exists('gzencode')) {
    			$errors[]=array('error'=>'PHP module zlib is not installed.<br/>', 'hint'=>'Please ask your server administrator to install the module.');
    			$web_server_restart= false;
    		}
    		if(!function_exists('iconv')) {
    			$errors[]=array('error'=>'PHP module iconv is not installed.<br/>', 'hint'=>'Please ask your server administrator to install the module.');
    			$web_server_restart= false;
    		}
    		if(!function_exists('simplexml_load_string')) {
    			$errors[]=array('error'=>'PHP module SimpleXML is not installed.<br/>', 'hint'=>'Please ask your server administrator to install the module.');
    			$web_server_restart= false;
    		}
    		if(floatval(phpversion())<5.3) {
    			$errors[]=array('error'=>'PHP 5.3 is required.<br/>', 'hint'=>'Please ask your server administrator to update PHP to version 5.3 or higher. PHP 5.2 is no longer supported by ownCloud and the PHP community.');
    			$web_server_restart= false;
    		}
    		if(!defined('PDO::ATTR_DRIVER_NAME')) {
    			$errors[]=array('error'=>'PHP PDO module is not installed.<br/>', 'hint'=>'Please ask your server administrator to install the module.');
    			$web_server_restart= false;
    		}
    
    		$handler = ini_get("session.save_handler");
    		if($handler == "files") {
    			$tmpDir = session_save_path();
    			if($tmpDir != ""){
    				if(!@is_writable($tmpDir)){
    					$errors[]=array('error' => 'The temporary folder used by PHP to save the session data is either incorrect or not writable! Please check : '.session_save_path().'<br/>',
    					'hint'=>'Please ask your server administrator to grant write access or define another temporary folder.');
    				}
    			}
    		}
    
    		if($web_server_restart) {
    			$errors[]=array('error'=>'PHP modules have been installed, but they are still listed as missing?<br/>', 'hint'=>'Please ask your server administrator to restart the web server.');
    		}
    
    		return $errors;
    	}
    
    	/**
    	* Check for correct file permissions of data directory
    	* @return array arrays with error messages and hints
    	*/
    	public static function checkDataDirectoryPermissions($dataDirectory) {
    		$errors = array();
    		if (stristr(PHP_OS, 'WIN')) {
    			//TODO: permissions checks for windows hosts
    		} else {
    			$permissionsModHint = 'Please change the permissions to 0770 so that the directory cannot be listed by other users.';
    			$prems = substr(decoct(@fileperms($dataDirectory)), -3);
    			if (substr($prems, -1) != '0') {
    				OC_Helper::chmodr($dataDirectory, 0770);
    				clearstatcache();
    				$prems = substr(decoct(@fileperms($dataDirectory)), -3);
    				if (substr($prems, 2, 1) != '0') {
    					$errors[] = array('error' => 'Data directory ('.$dataDirectory.') is readable for other users<br/>', 'hint' => $permissionsModHint);
    				}
    			}
    		}
    		return $errors;
    	}
    
    	public static function displayLoginPage($errors = array()) {
    		$parameters = array();
    		foreach( $errors as $key => $value ) {
    			$parameters[$value] = true;
    		}
    		if (!empty($_POST['user'])) {
    			$parameters["username"] = OC_Util::sanitizeHTML($_POST['user']).'"';
    			$parameters['user_autofocus'] = false;
    		} else {
    			$parameters["username"] = '';
    			$parameters['user_autofocus'] = true;
    		}
    		if (isset($_REQUEST['redirect_url'])) {
    			$redirect_url = OC_Util::sanitizeHTML($_REQUEST['redirect_url']);
    			$parameters['redirect_url'] = urlencode($redirect_url);
    		}
    
    		$parameters['alt_login'] = OC_App::getAlternativeLogIns();
    		OC_Template::printGuestPage("", "login", $parameters);
    	}
    
    
    	/**
    	 * Check if the app is enabled, redirects to home if not
    	 */
    	public static function checkAppEnabled($app) {
    		if( !OC_App::isEnabled($app)) {
    			header( 'Location: '.OC_Helper::linkToAbsolute( '', 'index.php' ));
    			exit();
    		}
    	}
    
    	/**
    	 * Check if the user is logged in, redirects to home if not. With
    	 * redirect URL parameter to the request URI.
    	 */
    	public static function checkLoggedIn() {
    		// Check if we are a user
    		if( !OC_User::isLoggedIn()) {
    			header( 'Location: '.OC_Helper::linkToAbsolute( '', 'index.php', array('redirect_url' => OC_Request::requestUri())));
    			exit();
    		}
    	}
    
    	/**
    	 * Check if the user is a admin, redirects to home if not
    	 */
    	public static function checkAdminUser() {
    		if( !OC_User::isAdminUser(OC_User::getUser())) {
    			header( 'Location: '.OC_Helper::linkToAbsolute( '', 'index.php' ));
    			exit();
    		}
    	}
    
    	/**
    	 * Check if the user is a subadmin, redirects to home if not
    	 * @return array $groups where the current user is subadmin
    	 */
    	public static function checkSubAdminUser() {
    		if(!OC_SubAdmin::isSubAdmin(OC_User::getUser())) {
    			header( 'Location: '.OC_Helper::linkToAbsolute( '', 'index.php' ));
    			exit();
    		}
    		return true;
    	}
    
    	/**
    	 * Redirect to the user default page
    	 */
    	public static function redirectToDefaultPage() {
    		if(isset($_REQUEST['redirect_url'])) {
    			$location = OC_Helper::makeURLAbsolute(urldecode($_REQUEST['redirect_url']));
    		}
    		else if (isset(OC::$REQUESTEDAPP) && !empty(OC::$REQUESTEDAPP)) {
    			$location = OC_Helper::linkToAbsolute( OC::$REQUESTEDAPP, 'index.php' );
    		}
    		else {
    			$defaultpage = OC_Appconfig::getValue('core', 'defaultpage');
    			if ($defaultpage) {
    				$location = OC_Helper::makeURLAbsolute(OC::$WEBROOT.'/'.$defaultpage);
    			}
    			else {
    				$location = OC_Helper::linkToAbsolute( 'files', 'index.php' );
    			}
    		}
    		OC_Log::write('core', 'redirectToDefaultPage: '.$location, OC_Log::DEBUG);
    		header( 'Location: '.$location );
    		exit();
    	}
    
    	/**
    	 * get an id unqiue for this instance
    	 * @return string
    	 */
    	public static function getInstanceId() {
    		$id=OC_Config::getValue('instanceid', null);
    		if(is_null($id)) {
    			$id=uniqid();
    			OC_Config::setValue('instanceid', $id);
    		}
    		return $id;
    	}
    
    	/**
    	 * @brief Static lifespan (in seconds) when a request token expires.
    	 * @see OC_Util::callRegister()
    	 * @see OC_Util::isCallRegistered()
    	 * @description
    	 * Also required for the client side to compute the piont in time when to
    	 * request a fresh token. The client will do so when nearly 97% of the
    	 * timespan coded here has expired.
    	 */
    	public static $callLifespan = 3600; // 3600 secs = 1 hour
    
    	/**
    	 * @brief Register an get/post call. Important to prevent CSRF attacks.
    	 * @todo Write howto: CSRF protection guide
    	 * @return $token Generated token.
    	 * @description
    	 * Creates a 'request token' (random) and stores it inside the session.
    	 * Ever subsequent (ajax) request must use such a valid token to succeed,
    	 * otherwise the request will be denied as a protection against CSRF.
    	 * The tokens expire after a fixed lifespan.
    	 * @see OC_Util::$callLifespan
    	 * @see OC_Util::isCallRegistered()
    	 */
    	public static function callRegister() {
    		// Check if a token exists
    		if(!isset($_SESSION['requesttoken'])) {
    			// No valid token found, generate a new one.
    			$requestToken = self::generate_random_bytes(20);
    			$_SESSION['requesttoken']=$requestToken;
    		} else {
    			// Valid token already exists, send it
    			$requestToken = $_SESSION['requesttoken'];
    		}
    		return($requestToken);
    	}
    
    	/**
    	 * @brief Check an ajax get/post call if the request token is valid.
    	 * @return boolean False if request token is not set or is invalid.
    	 * @see OC_Util::$callLifespan
    	 * @see OC_Util::callRegister()
    	 */
    	public static function isCallRegistered() {
    		if(isset($_GET['requesttoken'])) {
    			$token=$_GET['requesttoken'];
    		}elseif(isset($_POST['requesttoken'])) {
    			$token=$_POST['requesttoken'];
    		}elseif(isset($_SERVER['HTTP_REQUESTTOKEN'])) {
    			$token=$_SERVER['HTTP_REQUESTTOKEN'];
    		}else{
    			//no token found.
    			return false;
    		}
    
    		// Check if the token is valid
    		if($token !== $_SESSION['requesttoken']) {
    			// Not valid
    			return false;
    		} else {
    			// Valid token
    			return true;
    		}
    	}
    
    	/**
    	 * @brief Check an ajax get/post call if the request token is valid. exit if not.
    	 * Todo: Write howto
    	 */
    	public static function callCheck() {
    		if(!OC_Util::isCallRegistered()) {
    			exit;
    		}
    	}
    
    	/**
    	 * @brief Public function to sanitize HTML
    	 *
    	 * This function is used to sanitize HTML and should be applied on any
    	 * string or array of strings before displaying it on a web page.
    	 *
    	 * @param string or array of strings
    	 * @return array with sanitized strings or a single sanitized string, depends on the input parameter.
    	 */
    	public static function sanitizeHTML( &$value ) {
    		if (is_array($value) || is_object($value)) {
    			array_walk_recursive($value, 'OC_Util::sanitizeHTML');
    		} else {
    			$value = htmlentities($value, ENT_QUOTES, 'UTF-8'); //Specify encoding for PHP<5.4
    		}
    		return $value;
    	}
    
    
    	/**
    	 * Check if the htaccess file is working by creating a test file in the data directory and trying to access via http
    	 */
    	public static function ishtaccessworking() {
    		// testdata
    		$filename='/htaccesstest.txt';
    		$testcontent='testcontent';
    
    		// creating a test file
    		$testfile = OC_Config::getValue( "datadirectory", OC::$SERVERROOT."/data" ).'/'.$filename;
    
    		if(file_exists($testfile)) {// already running this test, possible recursive call
    			return false;
    		}
    
    		$fp = @fopen($testfile, 'w');
    		@fwrite($fp, $testcontent);
    		@fclose($fp);
    
    		// accessing the file via http
    		$url = OC_Helper::makeURLAbsolute(OC::$WEBROOT.'/data'.$filename);
    		$fp = @fopen($url, 'r');
    		$content=@fread($fp, 2048);
    		@fclose($fp);
    
    		// cleanup
    		@unlink($testfile);
    
    		// does it work ?
    		if($content==$testcontent) {
    			return(false);
    		}else{
    			return(true);
    		}
    	}
    
    	/**
    	 * we test if webDAV is working properly
    	 *
    	 * The basic assumption is that if the server returns 401/Not Authenticated for an unauthenticated PROPFIND
    	 * the web server it self is setup properly.
    	 *
    	 * Why not an authenticated PROFIND and other verbs?
    	 *  - We don't have the password available
    	 *  - We have no idea about other auth methods implemented (e.g. OAuth with Bearer header)
    	 *
    	 */
    	public static function isWebDAVWorking() {
            if (!function_exists('curl_init')) {
                return;
            }
    
    		$settings = array(
    			'baseUri' => OC_Helper::linkToRemote('webdav'),
    		);
    
    		$client = new \Sabre_DAV_Client($settings);
    
    		$return = true;
    		try {
    			// test PROPFIND
    			$client->propfind('', array('{DAV:}resourcetype'));
    		} catch(\Sabre_DAV_Exception_NotAuthenticated $e) {
    			$return = true;
    		} catch(\Exception $e) {
    			$return = false;
    		}
    
    		return $return;
    	}
    
    	/**
    	 * Check if the setlocal call doesn't work. This can happen if the right local packages are not available on the server.
    	 */
    	public static function issetlocaleworking() {
    		// setlocale test is pointless on Windows
    		if (OC_Util::runningOnWindows() ) {
    			return true;
    		}
    
    		$result=setlocale(LC_ALL, 'en_US.UTF-8');
    		if($result==false) {
    			return(false);
    		}else{
    			return(true);
    		}
    	}
    
    	/**
    	 * Check if the PHP module fileinfo is loaded.
    	 * @return bool
    	 */
    	public static function fileInfoLoaded() {
    		return function_exists('finfo_open');
    	}
    
    	/**
    	 * Check if the ownCloud server can connect to the internet
    	 */
    	public static function isinternetconnectionworking() {
    
    		// try to connect to owncloud.org to see if http connections to the internet are possible.
    		$connected = @fsockopen("www.owncloud.org", 80);
    		if ($connected) {
    			fclose($connected);
    			return true;
    		}else{
    
    			// second try in case one server is down
    			$connected = @fsockopen("apps.owncloud.com", 80);
    			if ($connected) {
    				fclose($connected);
    				return true;
    			}else{
    				return false;
    			}
    
    		}
    
    	}
    
    	/**
    	 * clear all levels of output buffering
    	 */
    	public static function obEnd(){
    		while (ob_get_level()) {
    			ob_end_clean();
    		}
    	}
    
    
    	/**
    	 * @brief Generates a cryptographical secure pseudorandom string
    	 * @param Int with the length of the random string
    	 * @return String
    	 * Please also update secureRNG_available if you change something here
    	 */
    	public static function generate_random_bytes($length = 30) {
    
    		// Try to use openssl_random_pseudo_bytes
    		if(function_exists('openssl_random_pseudo_bytes')) {
    			$pseudo_byte = bin2hex(openssl_random_pseudo_bytes($length, $strong));
    			if($strong == true) {
    				return substr($pseudo_byte, 0, $length); // Truncate it to match the length
    			}
    		}
    
    		// Try to use /dev/urandom
    		$fp = @file_get_contents('/dev/urandom', false, null, 0, $length);
    		if ($fp !== false) {
    			$string = substr(bin2hex($fp), 0, $length);
    			return $string;
    		}
    
    		// Fallback to mt_rand()
    		$characters = '0123456789';
    		$characters .= 'abcdefghijklmnopqrstuvwxyz';
    		$charactersLength = strlen($characters)-1;
    		$pseudo_byte = "";
    
    		// Select some random characters
    		for ($i = 0; $i < $length; $i++) {
    			$pseudo_byte .= $characters[mt_rand(0, $charactersLength)];
    		}
    		return $pseudo_byte;
    	}
    
    	/**
    	 * @brief Checks if a secure random number generator is available
    	 * @return bool
    	 */
    	public static function secureRNG_available() {
    
    		// Check openssl_random_pseudo_bytes
    		if(function_exists('openssl_random_pseudo_bytes')) {
    			openssl_random_pseudo_bytes(1, $strong);
    			if($strong == true) {
    				return true;
    			}
    		}
    
    		// Check /dev/urandom
    		$fp = @file_get_contents('/dev/urandom', false, null, 0, 1);
    		if ($fp !== false) {
    			return true;
    		}
    
    		return false;
    	}
    
    	/**
    	 * @Brief Get file content via curl.
    	 * @param string $url Url to get content
    	 * @return string of the response or false on error
    	 * This function get the content of a page via curl, if curl is enabled.
    	 * If not, file_get_element is used.
    	 */
    
    	public static function getUrlContent($url){
    
    		if  (function_exists('curl_init')) {
    
    			$curl = curl_init();
    
    			curl_setopt($curl, CURLOPT_HEADER, 0);
    			curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
    			curl_setopt($curl, CURLOPT_CONNECTTIMEOUT, 10);
    			curl_setopt($curl, CURLOPT_URL, $url);
    			curl_setopt($curl, CURLOPT_FOLLOWLOCATION, true);
    			curl_setopt($curl, CURLOPT_MAXREDIRS, 10);
    
    			curl_setopt($curl, CURLOPT_USERAGENT, "ownCloud Server Crawler");
    			if(OC_Config::getValue('proxy','')<>'') {
    				curl_setopt($curl, CURLOPT_PROXY, OC_Config::getValue('proxy'));
    			}
    			if(OC_Config::getValue('proxyuserpwd','')<>'') {
    				curl_setopt($curl, CURLOPT_PROXYUSERPWD, OC_Config::getValue('proxyuserpwd'));
    			}
    			$data = curl_exec($curl);
    			curl_close($curl);
    
    		} else {
    			$contextArray = null;
    
    			if(OC_Config::getValue('proxy','')<>'') {
    				$contextArray = array(
    					'http' => array(
    						'timeout' => 10,
    						'proxy' => OC_Config::getValue('proxy')
    					)
    				);
    			} else {
    				$contextArray = array(
    					'http' => array(
    						'timeout' => 10
    					)
    				);
    			}
    
    
    			$ctx = stream_context_create(
    				$contextArray
    			);
    			$data=@file_get_contents($url, 0, $ctx);
    
    		}
    		return $data;
    	}
    
    	/**
    	 * @return bool - well are we running on windows or not
    	 */
    	public static function runningOnWindows() {
    		return (substr(PHP_OS, 0, 3) === "WIN");
    	}
    
    }