<?php
/**
 * @version		$Id: session.php 18785 2010-09-07 01:14:57Z ian $
 * @copyright	Copyright (C) 2005 - 2010 Open Source Matters, Inc. All rights reserved.
 * @license		GNU General Public License version 2 or later; see LICENSE.txt
 */

// No direct access.
defined('JPATH_BASE') or die;

// Register the session storage class with the loader
JLoader::register('JSessionStorage', dirname(__FILE__).DS.'storage.php');

/**
 * Class for managing HTTP sessions
 *
 * Provides access to session-state values as well as session-level
 * settings and lifetime management methods.
 * Based on the standart PHP session handling mechanism it provides
 * for you more advanced features such as expire timeouts.
 *
 * @package		Joomla.Framework
 * @subpackage	Session
 * @since		1.5
 */
class JSession extends JObject
{
	/**
	 * Internal state.
	 *
	 * @var	string $_state one of 'active'|'expired'|'destroyed|'error'
	 * @see getState()
	 */
	protected	$_state	=	'active';

	/**
	 * Maximum age of unused session.
	 *
	 * @var	string $_expire minutes
	 */
	protected	$_expire	=	15;

	/**
	 * The session store object.
	 *
	 * @var	object A JSessionStorage object
	 */
	protected	$_store	=	null;

	/**
	 * Security policy.
	 *
	 * Default values:
	 *  - fix_browser
	 *  - fix_adress
	 *
	 * @var array $_security list of checks that will be done.
	 */
	protected $_security = array('fix_browser');

	/**
	 * Force cookies to be SSL only
	 *
	 * @default false
	 * @var bool $force_ssl
	 */
	protected $_force_ssl = false;

	/**
	 * Constructor
	 *
	 * @param string $storage
	 * @param array	$options	optional parameters
	 */
	public function __construct($store = 'none', $options = array())
	{
		// Need to destroy any existing sessions started with session.auto_start
		if (session_id()) {
			session_unset();
			session_destroy();
		}

		// set default sessios save handler
		ini_set('session.save_handler', 'files');

		// disable transparent sid support
		ini_set('session.use_trans_sid', '0');

		// create handler
		$this->_store = JSessionStorage::getInstance($store, $options);

		// set options
		$this->_setOptions($options);

		$this->_setCookieParams();

		// load the session
		$this->_start();

		// initialise the session
		$this->_setCounter();
		$this->_setTimers();

		$this->_state =	'active';

		// perform security checks
		$this->_validate();
	}

	/**
	 * Session object destructor
	 *
	 * @access private
	 * @since 1.5
	 */
	public function __destruct()
	{
		$this->close();
	}

	/**
	 * Returns the global Session object, only creating it
	 * if it doesn't already exist.
	 *
	 * @return	JSession	The Session object.
	 * @since	1.5
	 */
	public static function getInstance($handler, $options)
	{
		static $instance;

		if (!is_object($instance)) {
			$instance = new JSession($handler, $options);
		}

		return $instance;
	}

	/**
	 * Get current state of session
	 *
	 * @return string The session state
	 */
	public function getState()
	{
		return $this->_state;
	}

	/**
	 * Get expiration time in minutes
	 *
	 * @return integer The session expiration time in minutes
	 */
	public function getExpire()
	{
		return $this->_expire;
	}

	/**
	 * Get a session token, if a token isn't set yet one will be generated.
	 *
	 * Tokens are used to secure forms from spamming attacks. Once a token
	 * has been generated the system will check the post request to see if
	 * it is present, if not it will invalidate the session.
	 *
	 * @param	boolean  If true, force a new token to be created
	 * @return  string	The session token
	 */
	public function getToken($forceNew = false)
	{
		$token = $this->get('session.token');

		//create a token
		if ($token === null || $forceNew) {
			$token	=	$this->_createToken(12);
			$this->set('session.token', $token);
		}

		return $token;
	}

	/**
	 * Method to determine if a token exists in the session. If not the
	 * session will be set to expired
	 *
	 * @param  string	Hashed token to be verified
	 * @param  boolean  If true, expires the session
	 * @since  1.5
	 */
	public function hasToken($tCheck, $forceExpire = true)
	{
		// check if a token exists in the session
		$tStored = $this->get('session.token');

		//check token
		if (($tStored !== $tCheck)) {
			if ($forceExpire) {
				$this->_state = 'expired';
			}
			return false;
		}

		return true;
	}

	/**
	 * Method to determine a hash for anti-spoofing variable names
	 *
	 * @return	string  Hashed var name
	 * @since		1.5
	 * @static
	 */
	public static function getFormToken($forceNew = false)
	{
		$user			= JFactory::getUser();
		$session		= JFactory::getSession();
		$hash			= JApplication::getHash($user->get('id', 0).$session->getToken($forceNew));

		return $hash;
	}

	/**
	 * Get session name
	 *
	 * @return string The session name
	 */
	public function getName()
	{
		if ($this->_state === 'destroyed') {
			// @TODO : raise error
			return null;
		}
		return session_name();
	}

	/**
	 * Get session id
	 *
	 * @return string The session name
	 */
	public function getId()
	{
		if ($this->_state === 'destroyed') {
			// @TODO : raise error
			return null;
		}
		return session_id();
	}

	/**
	 * Get the session handlers
	 *
	 * @return array An array of available session handlers
	 */
	public static function getStores()
	{
		jimport('joomla.filesystem.folder');
		$handlers = JFolder::files(dirname(__FILE__).DS.'storage', '.php$');

		$names = array();
		foreach($handlers as $handler) {
			$name = substr($handler, 0, strrpos($handler, '.'));
			$class = 'JSessionStorage'.ucfirst($name);

			//Load the class only if needed
			if (!class_exists($class)) {
				require_once dirname(__FILE__).DS.'storage'.DS.$name.'.php';
			}

			if (call_user_func_array(array(trim($class), 'test'), array())) {
				$names[] = $name;
			}
		}

		return $names;
	}

	/**
	 * Check whether this session is currently created
	 *
	 * @return  boolean  True on success.
	 */
	public function isNew()
	{
		$counter = $this->get('session.counter');
		if ($counter === 1) {
			return true;
		}
		return false;
	}

	/**
	 * Get data from the session store
	 *
	 * @param	string  Name of a variable
	 * @param	mixed	Default value of a variable if not set
	 * @param	string  Namespace to use, default to 'default'
	 * @return  mixed	Value of a variable
	 */
	public function get($name, $default = null, $namespace = 'default')
	{
		$namespace = '__'.$namespace; //add prefix to namespace to avoid collisions

		if ($this->_state !== 'active' && $this->_state !== 'expired') {
			// @TODO :: generated error here
			$error = null;
			return $error;
		}

		if (isset($_SESSION[$namespace][$name])) {
			return $_SESSION[$namespace][$name];
		}
		return $default;
	}

	/**
	 * Set data into the session store.
	 *
	 * @param	string  Name of a variable.
	 * @param	mixed	Value of a variable.
	 * @param	string  Namespace to use, default to 'default'.
	 * @return  mixed	Old value of a variable.
	 */
	public function set($name, $value = null, $namespace = 'default')
	{
		$namespace = '__'.$namespace; //add prefix to namespace to avoid collisions

		if ($this->_state !== 'active') {
			// @TODO :: generated error here
			return null;
		}

		$old = isset($_SESSION[$namespace][$name]) ?  $_SESSION[$namespace][$name] : null;

		if (null === $value) {
			unset($_SESSION[$namespace][$name]);
		} else {
			$_SESSION[$namespace][$name] = $value;
		}

		return $old;
	}

	/**
	 * Check wheter data exists in the session store
	 *
	 * @param	string	Name of variable
	 * @param	string	Namespace to use, default to 'default'
	 * @return  boolean  True if the variable exists
	 */
	public function has($name, $namespace = 'default')
	{
		$namespace = '__'.$namespace; //add prefix to namespace to avoid collisions

		if ($this->_state !== 'active') {
			// @TODO :: generated error here
			return null;
		}

		return isset($_SESSION[$namespace][$name]);
	}

	/**
	 * Unset data from the session store
	 *
	 * @param  string  Name of variable
	 * @param  string  Namespace to use, default to 'default'
	 * @return mixed	The value from session or NULL if not set
	 */
	public function clear($name, $namespace = 'default')
	{
		$namespace = '__'.$namespace; //add prefix to namespace to avoid collisions

		if ($this->_state !== 'active') {
			// @TODO :: generated error here
			return null;
		}

		$value	=	null;
		if (isset($_SESSION[$namespace][$name])) {
			$value	=	$_SESSION[$namespace][$name];
			unset($_SESSION[$namespace][$name]);
		}

		return $value;
	}

	/**
	 * Start a session.
	 *
	 * Creates a session (or resumes the current one based on the state of the session)
	 *
	 * @return  boolean  true on success
	 */
	protected function _start()
	{
		//  start session if not startet
		if ($this->_state == 'restart') {
			session_id($this->_createId());
		} else {
			$session_name = session_name();
			if (!JRequest::getVar($session_name, false, 'COOKIE')) {
				if (JRequest::getVar($session_name)) {
					session_id(JRequest::getVar($session_name));
					setcookie($session_name, '', time() - 3600);
				}
			}
		}

		session_cache_limiter('none');
		session_start();

		// Send modified header for IE 6.0 Security Policy
		header('P3P: CP="NOI ADM DEV PSAi COM NAV OUR OTRo STP IND DEM"');

		return true;
	}

	/**
	 * Frees all session variables and destroys all data registered to a session
	 *
	 * This method resets the $_SESSION variable and destroys all of the data associated
	 * with the current session in its storage (file or DB). It forces new session to be
	 * started after this method is called. It does not unset the session cookie.
	 *
	 * @return  void
	 * @see	session_unset()
	 * @see	session_destroy()
	 */
	public function destroy()
	{
		// session was already destroyed
		if ($this->_state === 'destroyed') {
			return true;
		}

		// In order to kill the session altogether, like to log the user out, the session id
		// must also be unset. If a cookie is used to propagate the session id (default behavior),
		// then the session cookie must be deleted.
		if (isset($_COOKIE[session_name()])) {
			$config = JFactory::getConfig();
			$cookie_domain = $config->get('cookie_domain', '');
			$cookie_path = $config->get('cookie_path', '/');
			setcookie(session_name(), '', time()-42000, $cookie_path, $cookie_domain);
		}

		session_unset();
		session_destroy();

		$this->_state = 'destroyed';
		return true;
	}

	/**
	 * Restart an expired or locked session.
	 *
	 * @return  boolean  true on success
	 * @see	destroy
	 */
	public function restart()
	{
		$this->destroy();
		if ($this->_state !==  'destroyed') {
			// @TODO :: generated error here
			return false;
		}

		// Re-register the session handler after a session has been destroyed, to avoid PHP bug
		$this->_store->register();

		$this->_state	=	'restart';
		//regenerate session id
		$id	=	$this->_createId(strlen($this->getId()));
		session_id($id);
		$this->_start();
		$this->_state	=	'active';

		$this->_validate();
		$this->_setCounter();

		return true;
	}

	/**
	 * Create a new session and copy variables from the old one
	 *
	 * @return boolean $result true on success
	 */
	public function fork()
	{
		if ($this->_state !== 'active') {
			// @TODO :: generated error here
			return false;
		}

		// save values
		$values	= $_SESSION;

		// keep session config
		$trans	=	ini_get('session.use_trans_sid');
		if ($trans) {
			ini_set('session.use_trans_sid', 0);
		}
		$cookie	=	session_get_cookie_params();

		// create new session id
		$id	=	$this->_createId(strlen($this->getId()));

		// kill session
		session_destroy();

		// re-register the session store after a session has been destroyed, to avoid PHP bug
		$this->_store->register();

		// restore config
		ini_set('session.use_trans_sid', $trans);
		session_set_cookie_params($cookie['lifetime'], $cookie['path'], $cookie['domain'], $cookie['secure']);

		// restart session with new id
		session_id($id);
		session_start();

		return true;
	}

	/**
	 * Writes session data and ends session
	 *
	 * Session data is usually stored after your script terminated without the need
	 * to call JSession::close(),but as session data is locked to prevent concurrent
	 * writes only one script may operate on a session at any time. When using
	 * framesets together with sessions you will experience the frames loading one
	 * by one due to this locking. You can reduce the time needed to load all the
	 * frames by ending the session as soon as all changes to session variables are
	 * done.
	 *
	 * @see	session_write_close()
	 */
	public function close()
	{
		session_write_close();
	}

	/**
	 * Create a session id
	 *
	 * @return string Session ID
	 */
	protected function _createId()
	{
		$id = 0;
		while (strlen($id) < 32)  {
			$id .= mt_rand(0, mt_getrandmax());
		}

		$id	= md5(uniqid($id, true));
		return $id;
	}

	/**
	 * Set session cookie parameters
	 */
	protected function _setCookieParams()
	{
		$cookie	= session_get_cookie_params();
		if ($this->_force_ssl) {
			$cookie['secure'] = true;
		}

		$config = JFactory::getConfig();

		if($config->get('cookie_domain', '') != '') {
			$cookie['domain'] = $config->get('cookie_domain');
		}

		if($config->get('cookie_path', '') != '') {
			$cookie['path'] = $config->get('cookie_path');
		}
		session_set_cookie_params($cookie['lifetime'], $cookie['path'], $cookie['domain'], $cookie['secure']);
	}

	/**
	 * Create a token-string
	 *
	 * @param	int	length of string
	 * @return  string  generated token
	 */
	protected function _createToken($length = 32)
	{
		static $chars	=	'0123456789abcdef';
		$max			=	strlen($chars) - 1;
		$token			=	'';
		$name			=  session_name();
		for ($i = 0; $i < $length; ++$i) {
			$token .=	$chars[ (rand(0, $max)) ];
		}

		return md5($token.$name);
	}

	/**
	 * Set counter of session usage
	 *
	 * @return  boolean  true on success
	 */
	protected function _setCounter()
	{
		$counter = $this->get('session.counter', 0);
		++$counter;

		$this->set('session.counter', $counter);
		return true;
	}

	/**
	 * Set the session timers
	 *
	 * @return boolean $result true on success
	 */
	protected function _setTimers()
	{
		if (!$this->has('session.timer.start')) {
			$start	=	time();

			$this->set('session.timer.start' , $start);
			$this->set('session.timer.last'  , $start);
			$this->set('session.timer.now'	, $start);
		}

		$this->set('session.timer.last', $this->get('session.timer.now'));
		$this->set('session.timer.now', time());

		return true;
	}

	/**
	 * set additional session options
	 *
	 * @param	array	list of parameter
	 * @return  boolean  true on success
	 */
	protected function _setOptions(&$options)
	{
		// set name
		if (isset($options['name'])) {
			session_name(md5($options['name']));
		}

		// set id
		if (isset($options['id'])) {
			session_id($options['id']);
		}

		// set expire time
		if (isset($options['expire'])) {
			$this->_expire	=	$options['expire'];
		}

		// get security options
		if (isset($options['security'])) {
			$this->_security	=	explode(',', $options['security']);
		}

		if (isset($options['force_ssl'])) {
			$this->_force_ssl = (bool) $options['force_ssl'];
		}

		//sync the session maxlifetime
		ini_set('session.gc_maxlifetime', $this->_expire);

		return true;
	}

	/**
	 * Do some checks for security reason
	 *
	 * - timeout check (expire)
	 * - ip-fixiation
	 * - browser-fixiation
	 *
	 * If one check failed, session data has to be cleaned.
	 *
	 * @param	boolean  reactivate session
	 * @return  boolean  true on success
	 * @see		http://shiflett.org/articles/the-truth-about-sessions
	 */
	protected function _validate($restart = false)
	{
		// allow to restart a session
		if ($restart) {
			$this->_state	=	'active';

			$this->set('session.client.address'	, null);
			$this->set('session.client.forwarded'	, null);
			$this->set('session.client.browser'	, null);
			$this->set('session.token'				, null);
		}

		// check if session has expired
		if ($this->_expire) {
			$curTime =	$this->get('session.timer.now' , 0 );
			$maxTime =	$this->get('session.timer.last', 0) +  $this->_expire;

			// empty session variables
			if ($maxTime < $curTime) {
				$this->_state	=	'expired';
				return false;
			}
		}

		// record proxy forwarded for in the session in case we need it later
		if (isset($_SERVER['HTTP_X_FORWARDED_FOR'])) {
			$this->set('session.client.forwarded', $_SERVER['HTTP_X_FORWARDED_FOR']);
		}

		// check for client adress
		if (in_array('fix_adress', $this->_security) && isset($_SERVER['REMOTE_ADDR'])) {
			$ip	= $this->get('session.client.address');

			if ($ip === null) {
				$this->set('session.client.address', $_SERVER['REMOTE_ADDR']);
			} else if ($_SERVER['REMOTE_ADDR'] !== $ip) {
				$this->_state	=	'error';
				return false;
			}
		}

		// check for clients browser
		if (in_array('fix_browser', $this->_security) && isset($_SERVER['HTTP_USER_AGENT'])) {
			$browser = $this->get('session.client.browser');

			if ($browser === null) {
				$this->set('session.client.browser', $_SERVER['HTTP_USER_AGENT']);
			} else if ($_SERVER['HTTP_USER_AGENT'] !== $browser) {
//				$this->_state	=	'error';
//				return false;
			}
		}

		return true;
	}
}
