Session.php

<?php
/**
 * CakePHP(tm) : Rapid Development Framework (http://cakephp.org)
 * Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
 *
 * Licensed under The MIT License
 * For full copyright and license information, please see the LICENSE.txt
 * Redistributions of files must retain the above copyright notice.
 *
 * @copyright     Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
 * @link          http://cakephp.org CakePHP(tm) Project
 * @since         0.10.0
 * @license       http://www.opensource.org/licenses/mit-license.php MIT License
 */
namespace Cake\Network;

use Cake\Core\App;
use Cake\Core\Configure;
use Cake\Error;
use Cake\Utility\Hash;
use SessionHandlerInterface;

/**
 * This class is a wrapper for the native PHP session functions. It provides
 * with several defaults for the most common use cases for utilizing the session
 * via external handlers and helps with using session in cli without any warnings.
 *
 * Sessions can be created out of defaults using `Session::create()` or you can get
 * an instance of a new session by just instantiating this class and passing the full
 * options you want to use.
 *
 * When specific options are omitted, this class will take its defaults from the configuration
 * values from the `session.*` directives in php.ini. This class will also alter such
 * directives when configuration values are provided.
 */
class Session {

/**
 * The Session handler instace used as an engine for persisting the session data.
 *
 * @var SessionHandlerInterface
 */
	protected $_engine;

/**
 * Indicates whether the sessions has already started
 *
 * @var boolean
 */
	protected $_started;

/**
 * The time in seconds the session will be valid for
 *
 * @var int
 */
	protected $_lifetime;

/**
 * Returns a new instance of a session after building a configuration bundle for it.
 * This function allows an options array which will be used for configuring the session
 * and the handler to be used. The most important key in the configuration array is
 * `defaults`, which indicates the set of configurations to inherit from, the possible
 * defaults are:
 *
 * - php: just use session as configured in php.ini
 * - cache: Use the CakePHP caching system as an storage for the session, you will need
 *   to pass the `config` key with the name of an already configured Cache engine.
 * - database: Use the CakePHP ORM to persist and manage sessions. By default this requires
 *   a table in your database named `sessions` or a `model` key in the configuration
 *   to indicate which Table object to use.
 * - cake: Use files for storing the sessions, but let CakePHP manage them and decide
 *   where to store them.
 *
 * The full list of options follows:
 *
 * - defaults: either 'php', 'database', 'cache' or 'cake' as explained above.
 * - handler: An array containing the handler configuration
 * - ini: A list of php.ini directives to set before the session starts.
 * - timeout: The time in minutes the session should stay active
 *
 * @param array $sessionConfig
 * @return Cake\Network\Session
 * @see Session::__construct()
 */
	public static function create($sessionConfig = []) {
		if (isset($sessionConfig['defaults'])) {
			$defaults = static::_defaultConfig($sessionConfig['defaults']);
			if ($defaults) {
				$sessionConfig = Hash::merge($defaults, $sessionConfig);
			}
		}

		if (!isset($sessionConfig['ini']['session.cookie_secure']) && env('HTTPS')) {
			$sessionConfig['ini']['session.cookie_secure'] = 1;
		}

		if (!isset($sessionConfig['ini']['session.name'])) {
			$sessionConfig['ini']['session.name'] = $sessionConfig['cookie'];
		}

		if (!empty($sessionConfig['handler'])) {
			$sessionConfig['ini']['session.save_handler'] = 'user';
		}

		if (!isset($sessionConfig['ini']['session.cookie_httponly'])) {
			$sessionConfig['ini']['session.cookie_httponly'] = 1;
		}

		return new static($sessionConfig);
	}

/**
 * Get one of the prebaked default session configurations.
 *
 * @param string $name
 * @return bool|array
 */
	protected static function _defaultConfig($name) {
		$defaults = array(
			'php' => array(
				'checkAgent' => false,
				'cookie' => 'CAKEPHP',
				'ini' => array(
					'session.use_trans_sid' => 0,
				)
			),
			'cake' => array(
				'checkAgent' => false,
				'cookie' => 'CAKEPHP',
				'ini' => array(
					'session.use_trans_sid' => 0,
					'url_rewriter.tags' => '',
					'session.serialize_handler' => 'php',
					'session.use_cookies' => 1,
					'session.save_path' => TMP . 'sessions',
					'session.save_handler' => 'files'
				)
			),
			'cache' => array(
				'checkAgent' => false,
				'cookie' => 'CAKEPHP',
				'ini' => array(
					'session.use_trans_sid' => 0,
					'url_rewriter.tags' => '',
					'session.use_cookies' => 1,
					'session.save_handler' => 'user',
				),
				'handler' => array(
					'engine' => 'CacheSession',
					'config' => 'default'
				)
			),
			'database' => array(
				'checkAgent' => false,
				'cookie' => 'CAKEPHP',
				'ini' => array(
					'session.use_trans_sid' => 0,
					'url_rewriter.tags' => '',
					'session.use_cookies' => 1,
					'session.save_handler' => 'user',
					'session.serialize_handler' => 'php',
				),
				'handler' => array(
					'engine' => 'DatabaseSession'
				)
			)
		);

		if (isset($defaults[$name])) {
			return $defaults[$name];
		}

		return false;
	}

/**
 * Constructor.
 *
 * ### Configuration:
 *
 * - timeout: The time in minutes the session should be valid for
 * - ini: A list of ini directives to change before the session start.
 * - handler: An array containing at least the `class` key. To be used as the session
 *   engine for persisting data. The rest of the keys in the array will be passed as
 *   the configuration array for the engine. You can set the `class` key to an already
 *   instantiated session handler object.
 *
 * @param array The Configuration to apply to this session object
 */
	public function __construct(array $config = []) {
		if (isset($config['timeout'])) {
			$config['ini']['session.cookie_lifetime'] = 60 * $config['timeout'];
			$config['ini']['session.gc_maxlifetime'] = 60 * $config['timeout'];
		}

		if (!empty($config['ini']) && is_array($config['ini'])) {
			$this->options($config['ini']);
		}

		if (!empty($config['handler']['engine'])) {
			$class = $config['handler']['engine'];
			unset($config['handler']['engine']);
			session_set_save_handler($this->engine($class, $config['handler']), false);
		}

		$this->_lifetime = ini_get('session.gc_maxlifetime');
		session_register_shutdown();
	}

/**
 * Sets the session handler instance to use for this session.
 * If a string is passed for the first argument, it will be treated as the
 * class name and the second argument will be passed as the first argument
 * in the constructor.
 *
 * If an instance of a SessionHandlerInterface is provided as the first argument,
 * the handler will be set to it.
 *
 * If no arguments are passed it will return the currently configured handler instance
 * or null if none exists.
 *
 * @param string|\SessionHandlerInterface $class The session handler to use
 * @param array $options the options to pass to the SessionHandler constructor
 * @return \SessionHandlerInterface|null
 * @throws \InvalidArgumentException
 */
	public function engine($class = null, $options = []) {
		if ($class instanceof SessionHandlerInterface) {
			return $this->_engine = $class;
		}

		if ($class === null) {
			return $this->_engine;
		}

		$class = App::className($class, 'Network/Session');
		if (!class_exists($class)) {
			throw new \InvalidArgumentException(sprintf('The class %s does not exist.', $class));
		}

		$handler = new $class($options);
		if (!($handler instanceof SessionHandlerInterface)) {
			throw new \InvalidArgumentException(
				'Chosen SessionHandler does not implement SessionHandlerInterface, it cannot be used with an engine key.'
			);
		}

		return $this->_engine = $handler;
	}

/**
 * Calls ini_set for each of the keys in `$options` and set them
 * to the respective value in the passed array.
 *
 * ### Example:
 *
 * `$session->options(['session.use_cookies' => 1]);`
 *
 * @return void
 * @throws \RuntimeException if any directive could not be set
 */
	public function options(array $options) {
		if (session_status() === \PHP_SESSION_ACTIVE) {
			return;
		}

		foreach ($options as $setting => $value) {
			if (ini_set($setting, $value) === false) {
				throw new \RuntimeException(sprintf(
					sprintf('Unable to configure the session, setting %s failed.'),
					$setting
				));
			}
		}
	}

/**
 * Starts the Session.
 *
 * @return bool True if session was started
 * @throws \RuntimeException if the session was already started or headers were already
 * sent
 */
	public function start() {
		if ($this->_started) {
			return true;
		}

		if (php_sapi_name() === 'cli') {
			$_SESSION = [];
			return $this->_started = true;
		}

		if (session_status() === \PHP_SESSION_ACTIVE) {
			throw new \RuntimeException('Session was already started');
		}

		if (ini_get('session.use_cookies') && headers_sent($file, $line)) {
			throw new \RuntimeException(
				sprintf('Cannot start session, headers already sent in "%s" at line %d', $file, $line)
			);
		}

		if (!session_start()) {
			throw new \RuntimeException('Could not start the session');
		}
		
		$this->_started = true;

		if ($this->_timedOut()) {
			$this->destroy();
			return $this->start();
		}

		return $this->_started;
	}

/**
 * Determine if Session has already been started.
 *
 * @return bool True if session has been started.
 */
	public function started() {
		return $this->_started || session_status() === \PHP_SESSION_ACTIVE;
	}

/**
 * Returns true if given variable name is set in session.
 *
 * @param string $name Variable name to check for
 * @return bool True if variable is there
 */
	public function check($name = null) {
		if (empty($name)) {
			return false;
		}

		if ($this->_hasSession() && !$this->started()) {
			$this->start();
		}

		return Hash::get($_SESSION, $name) !== null;
	}

/**
 * Returns given session variable, or all of them, if no parameters given.
 *
 * @param string|array $name The name of the session variable (or a path as sent to Set.extract)
 * @return mixed The value of the session variable, null if session not available,
 *   session not started, or provided name not found in the session.
 */
	public function read($name = null) {
		if (empty($name) && $name !== null) {
			return null;
		}

		if ($this->_hasSession() && !$this->started()) {
			$this->start();
		}

		if (!isset($_SESSION)) {
			return null;
		}

		if ($name === null) {
			return isset($_SESSION) ? $_SESSION : [];
		}

		return Hash::get($_SESSION, $name);
	}

/**
 * Writes value to given session variable name.
 *
 * @param string|array $name Name of variable
 * @param string $value Value to write
 * @return bool True if the write was successful, false if the write failed
 */
	public function write($name, $value = null) {
		if (empty($name)) {
			return;
		}

		if (!$this->started()) {
			$this->start();
		}

		$write = $name;
		if (!is_array($name)) {
			$write = array($name => $value);
		}

		$data = $_SESSION ?: [];
		foreach ($write as $key => $val) {
			$data = Hash::insert($data, $key, $val);
		}

		$this->_overwrite($_SESSION, $data);
	}

/**
 * Returns the session id.
 * Calling this method will not auto start the session. You might have to manually
 * assert a started session.
 *
 * Passing an id into it, you can also replace the session id if the session
 * has not already been started.
 * Note that depending on the session handler, not all characters are allowed
 * within the session id. For example, the file session handler only allows
 * characters in the range a-z A-Z 0-9 , (comma) and - (minus).
 *
 * @param string $id Id to replace the current session id
 * @return string Session id
 */
	public function id($id = null) {
		if ($id !== null) {
			session_id($id);
		}

		return session_id();
	}

/**
 * Removes a variable from session.
 *
 * @param string $name Session variable to remove
 * @return bool Success
 */
	public function delete($name) {
		if ($this->check($name)) {
			$this->_overwrite($_SESSION, Hash::remove($_SESSION, $name));
		}
	}

/**
 * Used to write new data to _SESSION, since PHP doesn't like us setting the _SESSION var itself.
 *
 * @param array $old Set of old variables => values
 * @param array $new New set of variable => value
 * @return void
 */
	protected function _overwrite(&$old, $new) {
		if (!empty($old)) {
			foreach ($old as $key => $var) {
				if (!isset($new[$key])) {
					unset($old[$key]);
				}
			}
		}
		foreach ($new as $key => $var) {
			$old[$key] = $var;
		}
	}

/**
 * Helper method to destroy invalid sessions.
 *
 * @return void
 */
	public function destroy() {
		if ($this->_hasSession() && !$this->started()) {
			$this->start();
		}

		if (php_sapi_name() !== 'cli') {
			session_destroy();
		}

		$_SESSION = [];
		$this->_started = false;
	}

/**
 * Clears the session, the session id, and renews the session.
 *
 * @return void
 */
	public function clear() {
		$_SESSION = [];
		$this->renew();
	}

/**
 * Returns whether a session exists
 * @return bool
 */
	protected function _hasSession() {
		return !ini_get('session.use_cookies')
			|| isset($_COOKIE[session_name()])
			|| php_sapi_name() === 'cli';
	}

/**
 * Restarts this session.
 *
 * @return void
 */
	public function renew() {
		if (!$this->_hasSession() ||  php_sapi_name() === 'cli') {
			return;
		}

		$params = session_get_cookie_params();
		setcookie(
			session_name(), '', time() - 42000,
			$params['path'], $params['domain'],
			$params['secure'], $params['httponly']
		);
		session_regenerate_id(true);
	}

/**
 * Stores a single string under the "Message.flash" session key. This is useful
 * for persisting messages from one request to another that should be displayed
 * to the user.
 *
 * The options array accepts `key`, this is is useful for assigning a domain
 * to the flash message since you can only store one per domain.
 *
 * ### Example
 *
 * {{{
 *	$session->flash('Welcome, Mark', 'success');
 *	$session->flash('This is a message in a different domain', 'info', ['key' => 'another']);
 * }}}
 *
 * @param string $message the message to display to persist
 * @param string $type the type of message
 * @param array $options A list of extra options to persist related to this message
 * @return void
 */
	public function flash($message, $type = 'info', $options = []) {
		$options += ['key' => 'flash'];
		$key = $options['key'];
		unset($options['key']);
		$this->write("Message.$key", [
			'message' => $message,
			'type' => $type,
			'params' => $options
		]);
	}

/**
 * Returns the flash message stored in the given key if exists.
 *
 * @param string $key the message domain
 * @return array|null
 */
	public function readFlash($key = 'flash') {
		return $this->read("Message.$key");
	}

/**
 * Deletes the flash message stored in the given key
 *
 * @param string $key the message domain
 * @return void
 */
	public function deleteFlash($key = 'flash') {
		$this->delete("Message.$key");
	}

/**
 * Returns true if the session is no longer valid because the last time it was
 * accessed was after the configured timeout.
 *
 * @return boolean
 */
	protected function _timedOut() {
		$time = $this->read('Config.time');
		$result = false;

		$checkTime = $time !== null && $this->_lifetime > 0;
		if ($checkTime && (time() - $time > $this->_lifetime)) {
			$result = true;
		}

		$this->write('Config.time', time());
		return $result;
	}

}