<?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);
		}
		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);
		}
	}


	/**
	 * 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() {
		$result=setlocale(LC_ALL, 'en_US.UTF-8');
		if($result==false) {
			return(false);
		}else{
			return(true);
		}
	}

	/**
	 * 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_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");
	}

}