Merge CodeIgniter 3 support

9 files changed, 2853 insertions, 0 deletions

diff --git a/system/libraries/Session/Session.php b/system/libraries/Session/Session.php
new file mode 100644
index 000000000..eb433de64
--- /dev/null
+++ b/system/libraries/Session/Session.php
@@ -0,0 +1,985 @@
+<?php
+/**
+ * CodeIgniter
+ *
+ * An open source application development framework for PHP
+ *
+ * This content is released under the MIT License (MIT)
+ *
+ * Copyright (c) 2014 - 2017, British Columbia Institute of Technology
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ * @package	CodeIgniter
+ * @author	EllisLab Dev Team
+ * @copyright	Copyright (c) 2008 - 2014, EllisLab, Inc. (https://ellislab.com/)
+ * @copyright	Copyright (c) 2014 - 2017, British Columbia Institute of Technology (http://bcit.ca/)
+ * @license	http://opensource.org/licenses/MIT	MIT License
+ * @link	https://codeigniter.com
+ * @since	Version 2.0.0
+ * @filesource
+ */
+defined('BASEPATH') OR exit('No direct script access allowed');
+
+/**
+ * CodeIgniter Session Class
+ *
+ * @package		CodeIgniter
+ * @subpackage	Libraries
+ * @category	Sessions
+ * @author		Andrey Andreev
+ * @link		https://codeigniter.com/user_guide/libraries/sessions.html
+ */
+class CI_Session {
+
+	/**
+	 * Userdata array
+	 *
+	 * Just a reference to $_SESSION, for BC purposes.
+	 */
+	public $userdata;
+
+	protected $_driver = 'files';
+	protected $_config;
+	protected $_sid_regexp;
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Class constructor
+	 *
+	 * @param	array	$params	Configuration parameters
+	 * @return	void
+	 */
+	public function __construct(array $params = array())
+	{
+		// No sessions under CLI
+		if (is_cli())
+		{
+			log_message('debug', 'Session: Initialization under CLI aborted.');
+			return;
+		}
+		elseif ((bool) ini_get('session.auto_start'))
+		{
+			log_message('error', 'Session: session.auto_start is enabled in php.ini. Aborting.');
+			return;
+		}
+		elseif ( ! empty($params['driver']))
+		{
+			$this->_driver = $params['driver'];
+			unset($params['driver']);
+		}
+		elseif ($driver = config_item('sess_driver'))
+		{
+			$this->_driver = $driver;
+		}
+		// Note: BC workaround
+		elseif (config_item('sess_use_database'))
+		{
+			log_message('debug', 'Session: "sess_driver" is empty; using BC fallback to "sess_use_database".');
+			$this->_driver = 'database';
+		}
+
+		$class = $this->_ci_load_classes($this->_driver);
+
+		// Configuration ...
+		$this->_configure($params);
+		$this->_config['_sid_regexp'] = $this->_sid_regexp;
+
+		$class = new $class($this->_config);
+		if ($class instanceof SessionHandlerInterface)
+		{
+			if (is_php('5.4'))
+			{
+				session_set_save_handler($class, TRUE);
+			}
+			else
+			{
+				session_set_save_handler(
+					array($class, 'open'),
+					array($class, 'close'),
+					array($class, 'read'),
+					array($class, 'write'),
+					array($class, 'destroy'),
+					array($class, 'gc')
+				);
+
+				register_shutdown_function('session_write_close');
+			}
+		}
+		else
+		{
+			log_message('error', "Session: Driver '".$this->_driver."' doesn't implement SessionHandlerInterface. Aborting.");
+			return;
+		}
+
+		// Sanitize the cookie, because apparently PHP doesn't do that for userspace handlers
+		if (isset($_COOKIE[$this->_config['cookie_name']])
+			&& (
+				! is_string($_COOKIE[$this->_config['cookie_name']])
+				OR ! preg_match('#\A'.$this->_sid_regexp.'\z#', $_COOKIE[$this->_config['cookie_name']])
+			)
+		)
+		{
+			unset($_COOKIE[$this->_config['cookie_name']]);
+		}
+
+		session_start();
+
+		// Is session ID auto-regeneration configured? (ignoring ajax requests)
+		if ((empty($_SERVER['HTTP_X_REQUESTED_WITH']) OR strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) !== 'xmlhttprequest')
+			&& ($regenerate_time = config_item('sess_time_to_update')) > 0
+		)
+		{
+			if ( ! isset($_SESSION['__ci_last_regenerate']))
+			{
+				$_SESSION['__ci_last_regenerate'] = time();
+			}
+			elseif ($_SESSION['__ci_last_regenerate'] < (time() - $regenerate_time))
+			{
+				$this->sess_regenerate((bool) config_item('sess_regenerate_destroy'));
+			}
+		}
+		// Another work-around ... PHP doesn't seem to send the session cookie
+		// unless it is being currently created or regenerated
+		elseif (isset($_COOKIE[$this->_config['cookie_name']]) && $_COOKIE[$this->_config['cookie_name']] === session_id())
+		{
+			setcookie(
+				$this->_config['cookie_name'],
+				session_id(),
+				(empty($this->_config['cookie_lifetime']) ? 0 : time() + $this->_config['cookie_lifetime']),
+				$this->_config['cookie_path'],
+				$this->_config['cookie_domain'],
+				$this->_config['cookie_secure'],
+				TRUE
+			);
+		}
+
+		$this->_ci_init_vars();
+
+		log_message('info', "Session: Class initialized using '".$this->_driver."' driver.");
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * CI Load Classes
+	 *
+	 * An internal method to load all possible dependency and extension
+	 * classes. It kind of emulates the CI_Driver library, but is
+	 * self-sufficient.
+	 *
+	 * @param	string	$driver	Driver name
+	 * @return	string	Driver class name
+	 */
+	protected function _ci_load_classes($driver)
+	{
+		// PHP 5.4 compatibility
+		interface_exists('SessionHandlerInterface', FALSE) OR require_once(BASEPATH.'libraries/Session/SessionHandlerInterface.php');
+
+		$prefix = config_item('subclass_prefix');
+
+		if ( ! class_exists('CI_Session_driver', FALSE))
+		{
+			require_once(
+				file_exists(APPPATH.'libraries/Session/Session_driver.php')
+					? APPPATH.'libraries/Session/Session_driver.php'
+					: BASEPATH.'libraries/Session/Session_driver.php'
+			);
+
+			if (file_exists($file_path = APPPATH.'libraries/Session/'.$prefix.'Session_driver.php'))
+			{
+				require_once($file_path);
+			}
+		}
+
+		$class = 'Session_'.$driver.'_driver';
+
+		// Allow custom drivers without the CI_ or MY_ prefix
+		if ( ! class_exists($class, FALSE) && file_exists($file_path = APPPATH.'libraries/Session/drivers/'.$class.'.php'))
+		{
+			require_once($file_path);
+			if (class_exists($class, FALSE))
+			{
+				return $class;
+			}
+		}
+
+		if ( ! class_exists('CI_'.$class, FALSE))
+		{
+			if (file_exists($file_path = APPPATH.'libraries/Session/drivers/'.$class.'.php') OR file_exists($file_path = BASEPATH.'libraries/Session/drivers/'.$class.'.php'))
+			{
+				require_once($file_path);
+			}
+
+			if ( ! class_exists('CI_'.$class, FALSE) && ! class_exists($class, FALSE))
+			{
+				throw new UnexpectedValueException("Session: Configured driver '".$driver."' was not found. Aborting.");
+			}
+		}
+
+		if ( ! class_exists($prefix.$class, FALSE) && file_exists($file_path = APPPATH.'libraries/Session/drivers/'.$prefix.$class.'.php'))
+		{
+			require_once($file_path);
+			if (class_exists($prefix.$class, FALSE))
+			{
+				return $prefix.$class;
+			}
+			else
+			{
+				log_message('debug', 'Session: '.$prefix.$class.".php found but it doesn't declare class ".$prefix.$class.'.');
+			}
+		}
+
+		return 'CI_'.$class;
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Configuration
+	 *
+	 * Handle input parameters and configuration defaults
+	 *
+	 * @param	array	&$params	Input parameters
+	 * @return	void
+	 */
+	protected function _configure(&$params)
+	{
+		$expiration = config_item('sess_expiration');
+
+		if (isset($params['cookie_lifetime']))
+		{
+			$params['cookie_lifetime'] = (int) $params['cookie_lifetime'];
+		}
+		else
+		{
+			$params['cookie_lifetime'] = ( ! isset($expiration) && config_item('sess_expire_on_close'))
+				? 0 : (int) $expiration;
+		}
+
+		isset($params['cookie_name']) OR $params['cookie_name'] = config_item('sess_cookie_name');
+		if (empty($params['cookie_name']))
+		{
+			$params['cookie_name'] = ini_get('session.name');
+		}
+		else
+		{
+			ini_set('session.name', $params['cookie_name']);
+		}
+
+		isset($params['cookie_path']) OR $params['cookie_path'] = config_item('cookie_path');
+		isset($params['cookie_domain']) OR $params['cookie_domain'] = config_item('cookie_domain');
+		isset($params['cookie_secure']) OR $params['cookie_secure'] = (bool) config_item('cookie_secure');
+
+		session_set_cookie_params(
+			$params['cookie_lifetime'],
+			$params['cookie_path'],
+			$params['cookie_domain'],
+			$params['cookie_secure'],
+			TRUE // HttpOnly; Yes, this is intentional and not configurable for security reasons
+		);
+
+		if (empty($expiration))
+		{
+			$params['expiration'] = (int) ini_get('session.gc_maxlifetime');
+		}
+		else
+		{
+			$params['expiration'] = (int) $expiration;
+			ini_set('session.gc_maxlifetime', $expiration);
+		}
+
+		$params['match_ip'] = (bool) (isset($params['match_ip']) ? $params['match_ip'] : config_item('sess_match_ip'));
+
+		isset($params['save_path']) OR $params['save_path'] = config_item('sess_save_path');
+
+		$this->_config = $params;
+
+		// Security is king
+		ini_set('session.use_trans_sid', 0);
+		ini_set('session.use_strict_mode', 1);
+		ini_set('session.use_cookies', 1);
+		ini_set('session.use_only_cookies', 1);
+
+		$this->_configure_sid_length();
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Configure session ID length
+	 *
+	 * To make life easier, we used to force SHA-1 and 4 bits per
+	 * character on everyone. And of course, someone was unhappy.
+	 *
+	 * Then PHP 7.1 broke backwards-compatibility because ext/session
+	 * is such a mess that nobody wants to touch it with a pole stick,
+	 * and the one guy who does, nobody has the energy to argue with.
+	 *
+	 * So we were forced to make changes, and OF COURSE something was
+	 * going to break and now we have this pile of shit. -- Narf
+	 *
+	 * @return	void
+	 */
+	protected function _configure_sid_length()
+	{
+		if (PHP_VERSION_ID < 70100)
+		{
+			$hash_function = ini_get('session.hash_function');
+			if (ctype_digit($hash_function))
+			{
+				if ($hash_function !== '1')
+				{
+					ini_set('session.hash_function', 1);
+				}
+
+				$bits = 160;
+			}
+			elseif ( ! in_array($hash_function, hash_algos(), TRUE))
+			{
+				ini_set('session.hash_function', 1);
+				$bits = 160;
+			}
+			elseif (($bits = strlen(hash($hash_function, 'dummy', false)) * 4) < 160)
+			{
+				ini_set('session.hash_function', 1);
+				$bits = 160;
+			}
+
+			$bits_per_character = (int) ini_get('session.hash_bits_per_character');
+			$sid_length         = (int) ceil($bits / $bits_per_character);
+		}
+		else
+		{
+			$bits_per_character = (int) ini_get('session.sid_bits_per_character');
+			$sid_length         = (int) ini_get('session.sid_length');
+			if (($bits = $sid_length * $bits_per_character) < 160)
+			{
+				// Add as many more characters as necessary to reach at least 160 bits
+				$sid_length += (int) ceil((160 % $bits) / $bits_per_character);
+				ini_set('session.sid_length', $sid_length);
+			}
+		}
+
+		// Yes, 4,5,6 are the only known possible values as of 2016-10-27
+		switch ($bits_per_character)
+		{
+			case 4:
+				$this->_sid_regexp = '[0-9a-f]';
+				break;
+			case 5:
+				$this->_sid_regexp = '[0-9a-v]';
+				break;
+			case 6:
+				$this->_sid_regexp = '[0-9a-zA-Z,-]';
+				break;
+		}
+
+		$this->_sid_regexp .= '{'.$sid_length.'}';
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Handle temporary variables
+	 *
+	 * Clears old "flash" data, marks the new one for deletion and handles
+	 * "temp" data deletion.
+	 *
+	 * @return	void
+	 */
+	protected function _ci_init_vars()
+	{
+		if ( ! empty($_SESSION['__ci_vars']))
+		{
+			$current_time = time();
+
+			foreach ($_SESSION['__ci_vars'] as $key => &$value)
+			{
+				if ($value === 'new')
+				{
+					$_SESSION['__ci_vars'][$key] = 'old';
+				}
+				// Hacky, but 'old' will (implicitly) always be less than time() ;)
+				// DO NOT move this above the 'new' check!
+				elseif ($value < $current_time)
+				{
+					unset($_SESSION[$key], $_SESSION['__ci_vars'][$key]);
+				}
+			}
+
+			if (empty($_SESSION['__ci_vars']))
+			{
+				unset($_SESSION['__ci_vars']);
+			}
+		}
+
+		$this->userdata =& $_SESSION;
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Mark as flash
+	 *
+	 * @param	mixed	$key	Session data key(s)
+	 * @return	bool
+	 */
+	public function mark_as_flash($key)
+	{
+		if (is_array($key))
+		{
+			for ($i = 0, $c = count($key); $i < $c; $i++)
+			{
+				if ( ! isset($_SESSION[$key[$i]]))
+				{
+					return FALSE;
+				}
+			}
+
+			$new = array_fill_keys($key, 'new');
+
+			$_SESSION['__ci_vars'] = isset($_SESSION['__ci_vars'])
+				? array_merge($_SESSION['__ci_vars'], $new)
+				: $new;
+
+			return TRUE;
+		}
+
+		if ( ! isset($_SESSION[$key]))
+		{
+			return FALSE;
+		}
+
+		$_SESSION['__ci_vars'][$key] = 'new';
+		return TRUE;
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Get flash keys
+	 *
+	 * @return	array
+	 */
+	public function get_flash_keys()
+	{
+		if ( ! isset($_SESSION['__ci_vars']))
+		{
+			return array();
+		}
+
+		$keys = array();
+		foreach (array_keys($_SESSION['__ci_vars']) as $key)
+		{
+			is_int($_SESSION['__ci_vars'][$key]) OR $keys[] = $key;
+		}
+
+		return $keys;
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Unmark flash
+	 *
+	 * @param	mixed	$key	Session data key(s)
+	 * @return	void
+	 */
+	public function unmark_flash($key)
+	{
+		if (empty($_SESSION['__ci_vars']))
+		{
+			return;
+		}
+
+		is_array($key) OR $key = array($key);
+
+		foreach ($key as $k)
+		{
+			if (isset($_SESSION['__ci_vars'][$k]) && ! is_int($_SESSION['__ci_vars'][$k]))
+			{
+				unset($_SESSION['__ci_vars'][$k]);
+			}
+		}
+
+		if (empty($_SESSION['__ci_vars']))
+		{
+			unset($_SESSION['__ci_vars']);
+		}
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Mark as temp
+	 *
+	 * @param	mixed	$key	Session data key(s)
+	 * @param	int	$ttl	Time-to-live in seconds
+	 * @return	bool
+	 */
+	public function mark_as_temp($key, $ttl = 300)
+	{
+		$ttl += time();
+
+		if (is_array($key))
+		{
+			$temp = array();
+
+			foreach ($key as $k => $v)
+			{
+				// Do we have a key => ttl pair, or just a key?
+				if (is_int($k))
+				{
+					$k = $v;
+					$v = $ttl;
+				}
+				else
+				{
+					$v += time();
+				}
+
+				if ( ! isset($_SESSION[$k]))
+				{
+					return FALSE;
+				}
+
+				$temp[$k] = $v;
+			}
+
+			$_SESSION['__ci_vars'] = isset($_SESSION['__ci_vars'])
+				? array_merge($_SESSION['__ci_vars'], $temp)
+				: $temp;
+
+			return TRUE;
+		}
+
+		if ( ! isset($_SESSION[$key]))
+		{
+			return FALSE;
+		}
+
+		$_SESSION['__ci_vars'][$key] = $ttl;
+		return TRUE;
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Get temp keys
+	 *
+	 * @return	array
+	 */
+	public function get_temp_keys()
+	{
+		if ( ! isset($_SESSION['__ci_vars']))
+		{
+			return array();
+		}
+
+		$keys = array();
+		foreach (array_keys($_SESSION['__ci_vars']) as $key)
+		{
+			is_int($_SESSION['__ci_vars'][$key]) && $keys[] = $key;
+		}
+
+		return $keys;
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Unmark flash
+	 *
+	 * @param	mixed	$key	Session data key(s)
+	 * @return	void
+	 */
+	public function unmark_temp($key)
+	{
+		if (empty($_SESSION['__ci_vars']))
+		{
+			return;
+		}
+
+		is_array($key) OR $key = array($key);
+
+		foreach ($key as $k)
+		{
+			if (isset($_SESSION['__ci_vars'][$k]) && is_int($_SESSION['__ci_vars'][$k]))
+			{
+				unset($_SESSION['__ci_vars'][$k]);
+			}
+		}
+
+		if (empty($_SESSION['__ci_vars']))
+		{
+			unset($_SESSION['__ci_vars']);
+		}
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * __get()
+	 *
+	 * @param	string	$key	'session_id' or a session data key
+	 * @return	mixed
+	 */
+	public function __get($key)
+	{
+		// Note: Keep this order the same, just in case somebody wants to
+		//       use 'session_id' as a session data key, for whatever reason
+		if (isset($_SESSION[$key]))
+		{
+			return $_SESSION[$key];
+		}
+		elseif ($key === 'session_id')
+		{
+			return session_id();
+		}
+
+		return NULL;
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * __isset()
+	 *
+	 * @param	string	$key	'session_id' or a session data key
+	 * @return	bool
+	 */
+	public function __isset($key)
+	{
+		if ($key === 'session_id')
+		{
+			return (session_status() === PHP_SESSION_ACTIVE);
+		}
+
+		return isset($_SESSION[$key]);
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * __set()
+	 *
+	 * @param	string	$key	Session data key
+	 * @param	mixed	$value	Session data value
+	 * @return	void
+	 */
+	public function __set($key, $value)
+	{
+		$_SESSION[$key] = $value;
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Session destroy
+	 *
+	 * Legacy CI_Session compatibility method
+	 *
+	 * @return	void
+	 */
+	public function sess_destroy()
+	{
+		session_destroy();
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Session regenerate
+	 *
+	 * Legacy CI_Session compatibility method
+	 *
+	 * @param	bool	$destroy	Destroy old session data flag
+	 * @return	void
+	 */
+	public function sess_regenerate($destroy = FALSE)
+	{
+		$_SESSION['__ci_last_regenerate'] = time();
+		session_regenerate_id($destroy);
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Get userdata reference
+	 *
+	 * Legacy CI_Session compatibility method
+	 *
+	 * @returns	array
+	 */
+	public function &get_userdata()
+	{
+		return $_SESSION;
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Userdata (fetch)
+	 *
+	 * Legacy CI_Session compatibility method
+	 *
+	 * @param	string	$key	Session data key
+	 * @return	mixed	Session data value or NULL if not found
+	 */
+	public function userdata($key = NULL)
+	{
+		if (isset($key))
+		{
+			return isset($_SESSION[$key]) ? $_SESSION[$key] : NULL;
+		}
+		elseif (empty($_SESSION))
+		{
+			return array();
+		}
+
+		$userdata = array();
+		$_exclude = array_merge(
+			array('__ci_vars'),
+			$this->get_flash_keys(),
+			$this->get_temp_keys()
+		);
+
+		foreach (array_keys($_SESSION) as $key)
+		{
+			if ( ! in_array($key, $_exclude, TRUE))
+			{
+				$userdata[$key] = $_SESSION[$key];
+			}
+		}
+
+		return $userdata;
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Set userdata
+	 *
+	 * Legacy CI_Session compatibility method
+	 *
+	 * @param	mixed	$data	Session data key or an associative array
+	 * @param	mixed	$value	Value to store
+	 * @return	void
+	 */
+	public function set_userdata($data, $value = NULL)
+	{
+		if (is_array($data))
+		{
+			foreach ($data as $key => &$value)
+			{
+				$_SESSION[$key] = $value;
+			}
+
+			return;
+		}
+
+		$_SESSION[$data] = $value;
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Unset userdata
+	 *
+	 * Legacy CI_Session compatibility method
+	 *
+	 * @param	mixed	$key	Session data key(s)
+	 * @return	void
+	 */
+	public function unset_userdata($key)
+	{
+		if (is_array($key))
+		{
+			foreach ($key as $k)
+			{
+				unset($_SESSION[$k]);
+			}
+
+			return;
+		}
+
+		unset($_SESSION[$key]);
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * All userdata (fetch)
+	 *
+	 * Legacy CI_Session compatibility method
+	 *
+	 * @return	array	$_SESSION, excluding flash data items
+	 */
+	public function all_userdata()
+	{
+		return $this->userdata();
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Has userdata
+	 *
+	 * Legacy CI_Session compatibility method
+	 *
+	 * @param	string	$key	Session data key
+	 * @return	bool
+	 */
+	public function has_userdata($key)
+	{
+		return isset($_SESSION[$key]);
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Flashdata (fetch)
+	 *
+	 * Legacy CI_Session compatibility method
+	 *
+	 * @param	string	$key	Session data key
+	 * @return	mixed	Session data value or NULL if not found
+	 */
+	public function flashdata($key = NULL)
+	{
+		if (isset($key))
+		{
+			return (isset($_SESSION['__ci_vars'], $_SESSION['__ci_vars'][$key], $_SESSION[$key]) && ! is_int($_SESSION['__ci_vars'][$key]))
+				? $_SESSION[$key]
+				: NULL;
+		}
+
+		$flashdata = array();
+
+		if ( ! empty($_SESSION['__ci_vars']))
+		{
+			foreach ($_SESSION['__ci_vars'] as $key => &$value)
+			{
+				is_int($value) OR $flashdata[$key] = $_SESSION[$key];
+			}
+		}
+
+		return $flashdata;
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Set flashdata
+	 *
+	 * Legacy CI_Session compatibility method
+	 *
+	 * @param	mixed	$data	Session data key or an associative array
+	 * @param	mixed	$value	Value to store
+	 * @return	void
+	 */
+	public function set_flashdata($data, $value = NULL)
+	{
+		$this->set_userdata($data, $value);
+		$this->mark_as_flash(is_array($data) ? array_keys($data) : $data);
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Keep flashdata
+	 *
+	 * Legacy CI_Session compatibility method
+	 *
+	 * @param	mixed	$key	Session data key(s)
+	 * @return	void
+	 */
+	public function keep_flashdata($key)
+	{
+		$this->mark_as_flash($key);
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Temp data (fetch)
+	 *
+	 * Legacy CI_Session compatibility method
+	 *
+	 * @param	string	$key	Session data key
+	 * @return	mixed	Session data value or NULL if not found
+	 */
+	public function tempdata($key = NULL)
+	{
+		if (isset($key))
+		{
+			return (isset($_SESSION['__ci_vars'], $_SESSION['__ci_vars'][$key], $_SESSION[$key]) && is_int($_SESSION['__ci_vars'][$key]))
+				? $_SESSION[$key]
+				: NULL;
+		}
+
+		$tempdata = array();
+
+		if ( ! empty($_SESSION['__ci_vars']))
+		{
+			foreach ($_SESSION['__ci_vars'] as $key => &$value)
+			{
+				is_int($value) && $tempdata[$key] = $_SESSION[$key];
+			}
+		}
+
+		return $tempdata;
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Set tempdata
+	 *
+	 * Legacy CI_Session compatibility method
+	 *
+	 * @param	mixed	$data	Session data key or an associative array of items
+	 * @param	mixed	$value	Value to store
+	 * @param	int	$ttl	Time-to-live in seconds
+	 * @return	void
+	 */
+	public function set_tempdata($data, $value = NULL, $ttl = 300)
+	{
+		$this->set_userdata($data, $value);
+		$this->mark_as_temp(is_array($data) ? array_keys($data) : $data, $ttl);
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Unset tempdata
+	 *
+	 * Legacy CI_Session compatibility method
+	 *
+	 * @param	mixed	$data	Session data key(s)
+	 * @return	void
+	 */
+	public function unset_tempdata($key)
+	{
+		$this->unmark_temp($key);
+	}
+
+}
diff --git a/system/libraries/Session/SessionHandlerInterface.php b/system/libraries/Session/SessionHandlerInterface.php
new file mode 100644
index 000000000..2eef61db8
--- /dev/null
+++ b/system/libraries/Session/SessionHandlerInterface.php
@@ -0,0 +1,59 @@
+<?php
+/**
+ * CodeIgniter
+ *
+ * An open source application development framework for PHP
+ *
+ * This content is released under the MIT License (MIT)
+ *
+ * Copyright (c) 2014 - 2017, British Columbia Institute of Technology
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ * @package	CodeIgniter
+ * @author	EllisLab Dev Team
+ * @copyright	Copyright (c) 2008 - 2014, EllisLab, Inc. (https://ellislab.com/)
+ * @copyright	Copyright (c) 2014 - 2017, British Columbia Institute of Technology (http://bcit.ca/)
+ * @license	http://opensource.org/licenses/MIT	MIT License
+ * @link	https://codeigniter.com
+ * @since	Version 3.0.0
+ * @filesource
+ */
+defined('BASEPATH') OR exit('No direct script access allowed');
+
+/**
+ * SessionHandlerInterface
+ *
+ * PHP 5.4 compatibility interface
+ *
+ * @package	CodeIgniter
+ * @subpackage	Libraries
+ * @category	Sessions
+ * @author	Andrey Andreev
+ * @link	https://codeigniter.com/user_guide/libraries/sessions.html
+ */
+interface SessionHandlerInterface {
+
+	public function open($save_path, $name);
+	public function close();
+	public function read($session_id);
+	public function write($session_id, $session_data);
+	public function destroy($session_id);
+	public function gc($maxlifetime);
+}
diff --git a/system/libraries/Session/Session_driver.php b/system/libraries/Session/Session_driver.php
new file mode 100644
index 000000000..f32f14ae0
--- /dev/null
+++ b/system/libraries/Session/Session_driver.php
@@ -0,0 +1,191 @@
+<?php
+/**
+ * CodeIgniter
+ *
+ * An open source application development framework for PHP
+ *
+ * This content is released under the MIT License (MIT)
+ *
+ * Copyright (c) 2014 - 2017, British Columbia Institute of Technology
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ * @package	CodeIgniter
+ * @author	EllisLab Dev Team
+ * @copyright	Copyright (c) 2008 - 2014, EllisLab, Inc. (https://ellislab.com/)
+ * @copyright	Copyright (c) 2014 - 2017, British Columbia Institute of Technology (http://bcit.ca/)
+ * @license	http://opensource.org/licenses/MIT	MIT License
+ * @link	https://codeigniter.com
+ * @since	Version 3.0.0
+ * @filesource
+ */
+defined('BASEPATH') OR exit('No direct script access allowed');
+
+/**
+ * CodeIgniter Session Driver Class
+ *
+ * @package	CodeIgniter
+ * @subpackage	Libraries
+ * @category	Sessions
+ * @author	Andrey Andreev
+ * @link	https://codeigniter.com/user_guide/libraries/sessions.html
+ */
+abstract class CI_Session_driver implements SessionHandlerInterface {
+
+	protected $_config;
+
+	/**
+	 * Data fingerprint
+	 *
+	 * @var	bool
+	 */
+	protected $_fingerprint;
+
+	/**
+	 * Lock placeholder
+	 *
+	 * @var	mixed
+	 */
+	protected $_lock = FALSE;
+
+	/**
+	 * Read session ID
+	 *
+	 * Used to detect session_regenerate_id() calls because PHP only calls
+	 * write() after regenerating the ID.
+	 *
+	 * @var	string
+	 */
+	protected $_session_id;
+
+	/**
+	 * Success and failure return values
+	 *
+	 * Necessary due to a bug in all PHP 5 versions where return values
+	 * from userspace handlers are not handled properly. PHP 7 fixes the
+	 * bug, so we need to return different values depending on the version.
+	 *
+	 * @see	https://wiki.php.net/rfc/session.user.return-value
+	 * @var	mixed
+	 */
+	protected $_success, $_failure;
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Class constructor
+	 *
+	 * @param	array	$params	Configuration parameters
+	 * @return	void
+	 */
+	public function __construct(&$params)
+	{
+		$this->_config =& $params;
+
+		if (is_php('7'))
+		{
+			$this->_success = TRUE;
+			$this->_failure = FALSE;
+		}
+		else
+		{
+			$this->_success = 0;
+			$this->_failure = -1;
+		}
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Cookie destroy
+	 *
+	 * Internal method to force removal of a cookie by the client
+	 * when session_destroy() is called.
+	 *
+	 * @return	bool
+	 */
+	protected function _cookie_destroy()
+	{
+		return setcookie(
+			$this->_config['cookie_name'],
+			NULL,
+			1,
+			$this->_config['cookie_path'],
+			$this->_config['cookie_domain'],
+			$this->_config['cookie_secure'],
+			TRUE
+		);
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Get lock
+	 *
+	 * A dummy method allowing drivers with no locking functionality
+	 * (databases other than PostgreSQL and MySQL) to act as if they
+	 * do acquire a lock.
+	 *
+	 * @param	string	$session_id
+	 * @return	bool
+	 */
+	protected function _get_lock($session_id)
+	{
+		$this->_lock = TRUE;
+		return TRUE;
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Release lock
+	 *
+	 * @return	bool
+	 */
+	protected function _release_lock()
+	{
+		if ($this->_lock)
+		{
+			$this->_lock = FALSE;
+		}
+
+		return TRUE;
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Fail
+	 *
+	 * Drivers other than the 'files' one don't (need to) use the
+	 * session.save_path INI setting, but that leads to confusing
+	 * error messages emitted by PHP when open() or write() fail,
+	 * as the message contains session.save_path ...
+	 * To work around the problem, the drivers will call this method
+	 * so that the INI is set just in time for the error message to
+	 * be properly generated.
+	 *
+	 * @return	mixed
+	 */
+	protected function _fail()
+	{
+		ini_set('session.save_path', config_item('sess_save_path'));
+		return $this->_failure;
+	}
+}
diff --git a/system/libraries/Session/drivers/Session_database_driver.php b/system/libraries/Session/drivers/Session_database_driver.php
new file mode 100644
index 000000000..b519b782f
--- /dev/null
+++ b/system/libraries/Session/drivers/Session_database_driver.php
@@ -0,0 +1,420 @@
+<?php
+/**
+ * CodeIgniter
+ *
+ * An open source application development framework for PHP
+ *
+ * This content is released under the MIT License (MIT)
+ *
+ * Copyright (c) 2014 - 2017, British Columbia Institute of Technology
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ * @package	CodeIgniter
+ * @author	EllisLab Dev Team
+ * @copyright	Copyright (c) 2008 - 2014, EllisLab, Inc. (https://ellislab.com/)
+ * @copyright	Copyright (c) 2014 - 2017, British Columbia Institute of Technology (http://bcit.ca/)
+ * @license	http://opensource.org/licenses/MIT	MIT License
+ * @link	https://codeigniter.com
+ * @since	Version 3.0.0
+ * @filesource
+ */
+defined('BASEPATH') OR exit('No direct script access allowed');
+
+/**
+ * CodeIgniter Session Database Driver
+ *
+ * @package	CodeIgniter
+ * @subpackage	Libraries
+ * @category	Sessions
+ * @author	Andrey Andreev
+ * @link	https://codeigniter.com/user_guide/libraries/sessions.html
+ */
+class CI_Session_database_driver extends CI_Session_driver implements SessionHandlerInterface {
+
+	/**
+	 * DB object
+	 *
+	 * @var	object
+	 */
+	protected $_db;
+
+	/**
+	 * Row exists flag
+	 *
+	 * @var	bool
+	 */
+	protected $_row_exists = FALSE;
+
+	/**
+	 * Lock "driver" flag
+	 *
+	 * @var	string
+	 */
+	protected $_platform;
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Class constructor
+	 *
+	 * @param	array	$params	Configuration parameters
+	 * @return	void
+	 */
+	public function __construct(&$params)
+	{
+		parent::__construct($params);
+
+		$CI =& get_instance();
+		isset($CI->db) OR $CI->load->database();
+		$this->_db = $CI->db;
+
+		if ( ! $this->_db instanceof CI_DB_query_builder)
+		{
+			throw new Exception('Query Builder not enabled for the configured database. Aborting.');
+		}
+		elseif ($this->_db->pconnect)
+		{
+			throw new Exception('Configured database connection is persistent. Aborting.');
+		}
+		elseif ($this->_db->cache_on)
+		{
+			throw new Exception('Configured database connection has cache enabled. Aborting.');
+		}
+
+		$db_driver = $this->_db->dbdriver.(empty($this->_db->subdriver) ? '' : '_'.$this->_db->subdriver);
+		if (strpos($db_driver, 'mysql') !== FALSE)
+		{
+			$this->_platform = 'mysql';
+		}
+		elseif (in_array($db_driver, array('postgre', 'pdo_pgsql'), TRUE))
+		{
+			$this->_platform = 'postgre';
+		}
+
+		// Note: BC work-around for the old 'sess_table_name' setting, should be removed in the future.
+		if ( ! isset($this->_config['save_path']) && ($this->_config['save_path'] = config_item('sess_table_name')))
+		{
+			log_message('debug', 'Session: "sess_save_path" is empty; using BC fallback to "sess_table_name".');
+		}
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Open
+	 *
+	 * Initializes the database connection
+	 *
+	 * @param	string	$save_path	Table name
+	 * @param	string	$name		Session cookie name, unused
+	 * @return	bool
+	 */
+	public function open($save_path, $name)
+	{
+		if (empty($this->_db->conn_id) && ! $this->_db->db_connect())
+		{
+			return $this->_fail();
+		}
+
+		return $this->_success;
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Read
+	 *
+	 * Reads session data and acquires a lock
+	 *
+	 * @param	string	$session_id	Session ID
+	 * @return	string	Serialized session data
+	 */
+	public function read($session_id)
+	{
+		if ($this->_get_lock($session_id) !== FALSE)
+		{
+			// Prevent previous QB calls from messing with our queries
+			$this->_db->reset_query();
+
+			// Needed by write() to detect session_regenerate_id() calls
+			$this->_session_id = $session_id;
+
+			$this->_db
+				->select('data')
+				->from($this->_config['save_path'])
+				->where('id', $session_id);
+
+			if ($this->_config['match_ip'])
+			{
+				$this->_db->where('ip_address', $_SERVER['REMOTE_ADDR']);
+			}
+
+			if ( ! ($result = $this->_db->get()) OR ($result = $result->row()) === NULL)
+			{
+				// PHP7 will reuse the same SessionHandler object after
+				// ID regeneration, so we need to explicitly set this to
+				// FALSE instead of relying on the default ...
+				$this->_row_exists = FALSE;
+				$this->_fingerprint = md5('');
+				return '';
+			}
+
+			// PostgreSQL's variant of a BLOB datatype is Bytea, which is a
+			// PITA to work with, so we use base64-encoded data in a TEXT
+			// field instead.
+			$result = ($this->_platform === 'postgre')
+				? base64_decode(rtrim($result->data))
+				: $result->data;
+
+			$this->_fingerprint = md5($result);
+			$this->_row_exists = TRUE;
+			return $result;
+		}
+
+		$this->_fingerprint = md5('');
+		return '';
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Write
+	 *
+	 * Writes (create / update) session data
+	 *
+	 * @param	string	$session_id	Session ID
+	 * @param	string	$session_data	Serialized session data
+	 * @return	bool
+	 */
+	public function write($session_id, $session_data)
+	{
+		// Prevent previous QB calls from messing with our queries
+		$this->_db->reset_query();
+
+		// Was the ID regenerated?
+		if (isset($this->_session_id) && $session_id !== $this->_session_id)
+		{
+			if ( ! $this->_release_lock() OR ! $this->_get_lock($session_id))
+			{
+				return $this->_fail();
+			}
+
+			$this->_row_exists = FALSE;
+			$this->_session_id = $session_id;
+		}
+		elseif ($this->_lock === FALSE)
+		{
+			return $this->_fail();
+		}
+
+		if ($this->_row_exists === FALSE)
+		{
+			$insert_data = array(
+				'id' => $session_id,
+				'ip_address' => $_SERVER['REMOTE_ADDR'],
+				'timestamp' => time(),
+				'data' => ($this->_platform === 'postgre' ? base64_encode($session_data) : $session_data)
+			);
+
+			if ($this->_db->insert($this->_config['save_path'], $insert_data))
+			{
+				$this->_fingerprint = md5($session_data);
+				$this->_row_exists = TRUE;
+				return $this->_success;
+			}
+
+			return $this->_fail();
+		}
+
+		$this->_db->where('id', $session_id);
+		if ($this->_config['match_ip'])
+		{
+			$this->_db->where('ip_address', $_SERVER['REMOTE_ADDR']);
+		}
+
+		$update_data = array('timestamp' => time());
+		if ($this->_fingerprint !== md5($session_data))
+		{
+			$update_data['data'] = ($this->_platform === 'postgre')
+				? base64_encode($session_data)
+				: $session_data;
+		}
+
+		if ($this->_db->update($this->_config['save_path'], $update_data))
+		{
+			$this->_fingerprint = md5($session_data);
+			return $this->_success;
+		}
+
+		return $this->_fail();
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Close
+	 *
+	 * Releases locks
+	 *
+	 * @return	bool
+	 */
+	public function close()
+	{
+		return ($this->_lock && ! $this->_release_lock())
+			? $this->_fail()
+			: $this->_success;
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Destroy
+	 *
+	 * Destroys the current session.
+	 *
+	 * @param	string	$session_id	Session ID
+	 * @return	bool
+	 */
+	public function destroy($session_id)
+	{
+		if ($this->_lock)
+		{
+			// Prevent previous QB calls from messing with our queries
+			$this->_db->reset_query();
+
+			$this->_db->where('id', $session_id);
+			if ($this->_config['match_ip'])
+			{
+				$this->_db->where('ip_address', $_SERVER['REMOTE_ADDR']);
+			}
+
+			if ( ! $this->_db->delete($this->_config['save_path']))
+			{
+				return $this->_fail();
+			}
+		}
+
+		if ($this->close() === $this->_success)
+		{
+			$this->_cookie_destroy();
+			return $this->_success;
+		}
+
+		return $this->_fail();
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Garbage Collector
+	 *
+	 * Deletes expired sessions
+	 *
+	 * @param	int 	$maxlifetime	Maximum lifetime of sessions
+	 * @return	bool
+	 */
+	public function gc($maxlifetime)
+	{
+		// Prevent previous QB calls from messing with our queries
+		$this->_db->reset_query();
+
+		return ($this->_db->delete($this->_config['save_path'], 'timestamp < '.(time() - $maxlifetime)))
+			? $this->_success
+			: $this->_fail();
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Get lock
+	 *
+	 * Acquires a lock, depending on the underlying platform.
+	 *
+	 * @param	string	$session_id	Session ID
+	 * @return	bool
+	 */
+	protected function _get_lock($session_id)
+	{
+		if ($this->_platform === 'mysql')
+		{
+			$arg = md5($session_id.($this->_config['match_ip'] ? '_'.$_SERVER['REMOTE_ADDR'] : ''));
+			if ($this->_db->query("SELECT GET_LOCK('".$arg."', 300) AS ci_session_lock")->row()->ci_session_lock)
+			{
+				$this->_lock = $arg;
+				return TRUE;
+			}
+
+			return FALSE;
+		}
+		elseif ($this->_platform === 'postgre')
+		{
+			$arg = "hashtext('".$session_id."')".($this->_config['match_ip'] ? ", hashtext('".$_SERVER['REMOTE_ADDR']."')" : '');
+			if ($this->_db->simple_query('SELECT pg_advisory_lock('.$arg.')'))
+			{
+				$this->_lock = $arg;
+				return TRUE;
+			}
+
+			return FALSE;
+		}
+
+		return parent::_get_lock($session_id);
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Release lock
+	 *
+	 * Releases a previously acquired lock
+	 *
+	 * @return	bool
+	 */
+	protected function _release_lock()
+	{
+		if ( ! $this->_lock)
+		{
+			return TRUE;
+		}
+
+		if ($this->_platform === 'mysql')
+		{
+			if ($this->_db->query("SELECT RELEASE_LOCK('".$this->_lock."') AS ci_session_lock")->row()->ci_session_lock)
+			{
+				$this->_lock = FALSE;
+				return TRUE;
+			}
+
+			return FALSE;
+		}
+		elseif ($this->_platform === 'postgre')
+		{
+			if ($this->_db->simple_query('SELECT pg_advisory_unlock('.$this->_lock.')'))
+			{
+				$this->_lock = FALSE;
+				return TRUE;
+			}
+
+			return FALSE;
+		}
+
+		return parent::_release_lock();
+	}
+}
diff --git a/system/libraries/Session/drivers/Session_files_driver.php b/system/libraries/Session/drivers/Session_files_driver.php
new file mode 100644
index 000000000..8860ef667
--- /dev/null
+++ b/system/libraries/Session/drivers/Session_files_driver.php
@@ -0,0 +1,406 @@
+<?php
+/**
+ * CodeIgniter
+ *
+ * An open source application development framework for PHP
+ *
+ * This content is released under the MIT License (MIT)
+ *
+ * Copyright (c) 2014 - 2017, British Columbia Institute of Technology
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ * @package	CodeIgniter
+ * @author	EllisLab Dev Team
+ * @copyright	Copyright (c) 2008 - 2014, EllisLab, Inc. (https://ellislab.com/)
+ * @copyright	Copyright (c) 2014 - 2017, British Columbia Institute of Technology (http://bcit.ca/)
+ * @license	http://opensource.org/licenses/MIT	MIT License
+ * @link	https://codeigniter.com
+ * @since	Version 3.0.0
+ * @filesource
+*/
+defined('BASEPATH') OR exit('No direct script access allowed');
+
+/**
+ * CodeIgniter Session Files Driver
+ *
+ * @package	CodeIgniter
+ * @subpackage	Libraries
+ * @category	Sessions
+ * @author	Andrey Andreev
+ * @link	https://codeigniter.com/user_guide/libraries/sessions.html
+ */
+class CI_Session_files_driver extends CI_Session_driver implements SessionHandlerInterface {
+
+	/**
+	 * Save path
+	 *
+	 * @var	string
+	 */
+	protected $_save_path;
+
+	/**
+	 * File handle
+	 *
+	 * @var	resource
+	 */
+	protected $_file_handle;
+
+	/**
+	 * File name
+	 *
+	 * @var	resource
+	 */
+	protected $_file_path;
+
+	/**
+	 * File new flag
+	 *
+	 * @var	bool
+	 */
+	protected $_file_new;
+
+	/**
+	 * Validate SID regular expression
+	 *
+	 * @var	string
+	 */
+	protected $_sid_regexp;
+
+	/**
+	 * mbstring.func_overload flag
+	 *
+	 * @var	bool
+	 */
+	protected static $func_overload;
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Class constructor
+	 *
+	 * @param	array	$params	Configuration parameters
+	 * @return	void
+	 */
+	public function __construct(&$params)
+	{
+		parent::__construct($params);
+
+		if (isset($this->_config['save_path']))
+		{
+			$this->_config['save_path'] = rtrim($this->_config['save_path'], '/\\');
+			ini_set('session.save_path', $this->_config['save_path']);
+		}
+		else
+		{
+			log_message('debug', 'Session: "sess_save_path" is empty; using "session.save_path" value from php.ini.');
+			$this->_config['save_path'] = rtrim(ini_get('session.save_path'), '/\\');
+		}
+
+		$this->_sid_regexp = $this->_config['_sid_regexp'];
+
+		isset(self::$func_overload) OR self::$func_overload = (extension_loaded('mbstring') && ini_get('mbstring.func_overload'));
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Open
+	 *
+	 * Sanitizes the save_path directory.
+	 *
+	 * @param	string	$save_path	Path to session files' directory
+	 * @param	string	$name		Session cookie name
+	 * @return	bool
+	 */
+	public function open($save_path, $name)
+	{
+		if ( ! is_dir($save_path))
+		{
+			if ( ! mkdir($save_path, 0700, TRUE))
+			{
+				throw new Exception("Session: Configured save path '".$this->_config['save_path']."' is not a directory, doesn't exist or cannot be created.");
+			}
+		}
+		elseif ( ! is_writable($save_path))
+		{
+			throw new Exception("Session: Configured save path '".$this->_config['save_path']."' is not writable by the PHP process.");
+		}
+
+		$this->_config['save_path'] = $save_path;
+		$this->_file_path = $this->_config['save_path'].DIRECTORY_SEPARATOR
+			.$name // we'll use the session cookie name as a prefix to avoid collisions
+			.($this->_config['match_ip'] ? md5($_SERVER['REMOTE_ADDR']) : '');
+
+		return $this->_success;
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Read
+	 *
+	 * Reads session data and acquires a lock
+	 *
+	 * @param	string	$session_id	Session ID
+	 * @return	string	Serialized session data
+	 */
+	public function read($session_id)
+	{
+		// This might seem weird, but PHP 5.6 introduces session_reset(),
+		// which re-reads session data
+		if ($this->_file_handle === NULL)
+		{
+			$this->_file_new = ! file_exists($this->_file_path.$session_id);
+
+			if (($this->_file_handle = fopen($this->_file_path.$session_id, 'c+b')) === FALSE)
+			{
+				log_message('error', "Session: Unable to open file '".$this->_file_path.$session_id."'.");
+				return $this->_failure;
+			}
+
+			if (flock($this->_file_handle, LOCK_EX) === FALSE)
+			{
+				log_message('error', "Session: Unable to obtain lock for file '".$this->_file_path.$session_id."'.");
+				fclose($this->_file_handle);
+				$this->_file_handle = NULL;
+				return $this->_failure;
+			}
+
+			// Needed by write() to detect session_regenerate_id() calls
+			$this->_session_id = $session_id;
+
+			if ($this->_file_new)
+			{
+				chmod($this->_file_path.$session_id, 0600);
+				$this->_fingerprint = md5('');
+				return '';
+			}
+		}
+		// We shouldn't need this, but apparently we do ...
+		// See https://github.com/bcit-ci/CodeIgniter/issues/4039
+		elseif ($this->_file_handle === FALSE)
+		{
+			return $this->_failure;
+		}
+		else
+		{
+			rewind($this->_file_handle);
+		}
+
+		$session_data = '';
+		for ($read = 0, $length = filesize($this->_file_path.$session_id); $read < $length; $read += self::strlen($buffer))
+		{
+			if (($buffer = fread($this->_file_handle, $length - $read)) === FALSE)
+			{
+				break;
+			}
+
+			$session_data .= $buffer;
+		}
+
+		$this->_fingerprint = md5($session_data);
+		return $session_data;
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Write
+	 *
+	 * Writes (create / update) session data
+	 *
+	 * @param	string	$session_id	Session ID
+	 * @param	string	$session_data	Serialized session data
+	 * @return	bool
+	 */
+	public function write($session_id, $session_data)
+	{
+		// If the two IDs don't match, we have a session_regenerate_id() call
+		// and we need to close the old handle and open a new one
+		if ($session_id !== $this->_session_id && ($this->close() === $this->_failure OR $this->read($session_id) === $this->_failure))
+		{
+			return $this->_failure;
+		}
+
+		if ( ! is_resource($this->_file_handle))
+		{
+			return $this->_failure;
+		}
+		elseif ($this->_fingerprint === md5($session_data))
+		{
+			return ( ! $this->_file_new && ! touch($this->_file_path.$session_id))
+				? $this->_failure
+				: $this->_success;
+		}
+
+		if ( ! $this->_file_new)
+		{
+			ftruncate($this->_file_handle, 0);
+			rewind($this->_file_handle);
+		}
+
+		if (($length = strlen($session_data)) > 0)
+		{
+			for ($written = 0; $written < $length; $written += $result)
+			{
+				if (($result = fwrite($this->_file_handle, substr($session_data, $written))) === FALSE)
+				{
+					break;
+				}
+			}
+
+			if ( ! is_int($result))
+			{
+				$this->_fingerprint = md5(substr($session_data, 0, $written));
+				log_message('error', 'Session: Unable to write data.');
+				return $this->_failure;
+			}
+		}
+
+		$this->_fingerprint = md5($session_data);
+		return $this->_success;
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Close
+	 *
+	 * Releases locks and closes file descriptor.
+	 *
+	 * @return	bool
+	 */
+	public function close()
+	{
+		if (is_resource($this->_file_handle))
+		{
+			flock($this->_file_handle, LOCK_UN);
+			fclose($this->_file_handle);
+
+			$this->_file_handle = $this->_file_new = $this->_session_id = NULL;
+		}
+
+		return $this->_success;
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Destroy
+	 *
+	 * Destroys the current session.
+	 *
+	 * @param	string	$session_id	Session ID
+	 * @return	bool
+	 */
+	public function destroy($session_id)
+	{
+		if ($this->close() === $this->_success)
+		{
+			if (file_exists($this->_file_path.$session_id))
+			{
+				$this->_cookie_destroy();
+				return unlink($this->_file_path.$session_id)
+					? $this->_success
+					: $this->_failure;
+			}
+
+			return $this->_success;
+		}
+		elseif ($this->_file_path !== NULL)
+		{
+			clearstatcache();
+			if (file_exists($this->_file_path.$session_id))
+			{
+				$this->_cookie_destroy();
+				return unlink($this->_file_path.$session_id)
+					? $this->_success
+					: $this->_failure;
+			}
+
+			return $this->_success;
+		}
+
+		return $this->_failure;
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Garbage Collector
+	 *
+	 * Deletes expired sessions
+	 *
+	 * @param	int 	$maxlifetime	Maximum lifetime of sessions
+	 * @return	bool
+	 */
+	public function gc($maxlifetime)
+	{
+		if ( ! is_dir($this->_config['save_path']) OR ($directory = opendir($this->_config['save_path'])) === FALSE)
+		{
+			log_message('debug', "Session: Garbage collector couldn't list files under directory '".$this->_config['save_path']."'.");
+			return $this->_failure;
+		}
+
+		$ts = time() - $maxlifetime;
+
+		$pattern = ($this->_config['match_ip'] === TRUE)
+			? '[0-9a-f]{32}'
+			: '';
+
+		$pattern = sprintf(
+			'#\A%s'.$pattern.$this->_sid_regexp.'\z#',
+			preg_quote($this->_config['cookie_name'])
+		);
+
+		while (($file = readdir($directory)) !== FALSE)
+		{
+			// If the filename doesn't match this pattern, it's either not a session file or is not ours
+			if ( ! preg_match($pattern, $file)
+				OR ! is_file($this->_config['save_path'].DIRECTORY_SEPARATOR.$file)
+				OR ($mtime = filemtime($this->_config['save_path'].DIRECTORY_SEPARATOR.$file)) === FALSE
+				OR $mtime > $ts)
+			{
+				continue;
+			}
+
+			unlink($this->_config['save_path'].DIRECTORY_SEPARATOR.$file);
+		}
+
+		closedir($directory);
+
+		return $this->_success;
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
+	 * Byte-safe strlen()
+	 *
+	 * @param	string	$str
+	 * @return	int
+	 */
+	protected static function strlen($str)
+	{
+		return (self::$func_overload)
+			? mb_strlen($str, '8bit')
+			: strlen($str);
+	}
+}
diff --git a/system/libraries/Session/drivers/Session_memcached_driver.php b/system/libraries/Session/drivers/Session_memcached_driver.php
new file mode 100644
index 000000000..2556bf0f7
--- /dev/null
+++ b/system/libraries/Session/drivers/Session_memcached_driver.php
@@ -0,0 +1,375 @@
+<?php
+/**
+ * CodeIgniter
+ *
+ * An open source application development framework for PHP
+ *
+ * This content is released under the MIT License (MIT)
+ *
+ * Copyright (c) 2014 - 2017, British Columbia Institute of Technology
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ * @package	CodeIgniter
+ * @author	EllisLab Dev Team
+ * @copyright	Copyright (c) 2008 - 2014, EllisLab, Inc. (https://ellislab.com/)
+ * @copyright	Copyright (c) 2014 - 2017, British Columbia Institute of Technology (http://bcit.ca/)
+ * @license	http://opensource.org/licenses/MIT	MIT License
+ * @link	https://codeigniter.com
+ * @since	Version 3.0.0
+ * @filesource
+ */
+defined('BASEPATH') OR exit('No direct script access allowed');
+
+/**
+ * CodeIgniter Session Memcached Driver
+ *
+ * @package	CodeIgniter
+ * @subpackage	Libraries
+ * @category	Sessions
+ * @author	Andrey Andreev
+ * @link	https://codeigniter.com/user_guide/libraries/sessions.html
+ */
+class CI_Session_memcached_driver extends CI_Session_driver implements SessionHandlerInterface {
+
+	/**
+	 * Memcached instance
+	 *
+	 * @var	Memcached
+	 */
+	protected $_memcached;
+
+	/**
+	 * Key prefix
+	 *
+	 * @var	string
+	 */
+	protected $_key_prefix = 'ci_session:';
+
+	/**
+	 * Lock key
+	 *
+	 * @var	string
+	 */
+	protected $_lock_key;
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Class constructor
+	 *
+	 * @param	array	$params	Configuration parameters
+	 * @return	void
+	 */
+	public function __construct(&$params)
+	{
+		parent::__construct($params);
+
+		if (empty($this->_config['save_path']))
+		{
+			log_message('error', 'Session: No Memcached save path configured.');
+		}
+
+		if ($this->_config['match_ip'] === TRUE)
+		{
+			$this->_key_prefix .= $_SERVER['REMOTE_ADDR'].':';
+		}
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Open
+	 *
+	 * Sanitizes save_path and initializes connections.
+	 *
+	 * @param	string	$save_path	Server path(s)
+	 * @param	string	$name		Session cookie name, unused
+	 * @return	bool
+	 */
+	public function open($save_path, $name)
+	{
+		$this->_memcached = new Memcached();
+		$this->_memcached->setOption(Memcached::OPT_BINARY_PROTOCOL, TRUE); // required for touch() usage
+		$server_list = array();
+		foreach ($this->_memcached->getServerList() as $server)
+		{
+			$server_list[] = $server['host'].':'.$server['port'];
+		}
+
+		if ( ! preg_match_all('#,?([^,:]+)\:(\d{1,5})(?:\:(\d+))?#', $this->_config['save_path'], $matches, PREG_SET_ORDER))
+		{
+			$this->_memcached = NULL;
+			log_message('error', 'Session: Invalid Memcached save path format: '.$this->_config['save_path']);
+			return $this->_fail();
+		}
+
+		foreach ($matches as $match)
+		{
+			// If Memcached already has this server (or if the port is invalid), skip it
+			if (in_array($match[1].':'.$match[2], $server_list, TRUE))
+			{
+				log_message('debug', 'Session: Memcached server pool already has '.$match[1].':'.$match[2]);
+				continue;
+			}
+
+			if ( ! $this->_memcached->addServer($match[1], $match[2], isset($match[3]) ? $match[3] : 0))
+			{
+				log_message('error', 'Could not add '.$match[1].':'.$match[2].' to Memcached server pool.');
+			}
+			else
+			{
+				$server_list[] = $match[1].':'.$match[2];
+			}
+		}
+
+		if (empty($server_list))
+		{
+			log_message('error', 'Session: Memcached server pool is empty.');
+			return $this->_fail();
+		}
+
+		return $this->_success;
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Read
+	 *
+	 * Reads session data and acquires a lock
+	 *
+	 * @param	string	$session_id	Session ID
+	 * @return	string	Serialized session data
+	 */
+	public function read($session_id)
+	{
+		if (isset($this->_memcached) && $this->_get_lock($session_id))
+		{
+			// Needed by write() to detect session_regenerate_id() calls
+			$this->_session_id = $session_id;
+
+			$session_data = (string) $this->_memcached->get($this->_key_prefix.$session_id);
+			$this->_fingerprint = md5($session_data);
+			return $session_data;
+		}
+
+		return $this->_fail();
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Write
+	 *
+	 * Writes (create / update) session data
+	 *
+	 * @param	string	$session_id	Session ID
+	 * @param	string	$session_data	Serialized session data
+	 * @return	bool
+	 */
+	public function write($session_id, $session_data)
+	{
+		if ( ! isset($this->_memcached, $this->_lock_key))
+		{
+			return $this->_fail();
+		}
+		// Was the ID regenerated?
+		elseif ($session_id !== $this->_session_id)
+		{
+			if ( ! $this->_release_lock() OR ! $this->_get_lock($session_id))
+			{
+				return $this->_fail();
+			}
+
+			$this->_fingerprint = md5('');
+			$this->_session_id = $session_id;
+		}
+
+		$key = $this->_key_prefix.$session_id;
+
+		$this->_memcached->replace($this->_lock_key, time(), 300);
+		if ($this->_fingerprint !== ($fingerprint = md5($session_data)))
+		{
+			if ($this->_memcached->set($key, $session_data, $this->_config['expiration']))
+			{
+				$this->_fingerprint = $fingerprint;
+				return $this->_success;
+			}
+
+			return $this->_fail();
+		}
+		elseif (
+			$this->_memcached->touch($key, $this->_config['expiration'])
+			OR ($this->_memcached->getResultCode() === Memcached::RES_NOTFOUND && $this->_memcached->set($key, $session_data, $this->_config['expiration']))
+		)
+		{
+			return $this->_success;
+		}
+
+		return $this->_fail();
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Close
+	 *
+	 * Releases locks and closes connection.
+	 *
+	 * @return	bool
+	 */
+	public function close()
+	{
+		if (isset($this->_memcached))
+		{
+			$this->_release_lock();
+			if ( ! $this->_memcached->quit())
+			{
+				return $this->_fail();
+			}
+
+			$this->_memcached = NULL;
+			return $this->_success;
+		}
+
+		return $this->_fail();
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Destroy
+	 *
+	 * Destroys the current session.
+	 *
+	 * @param	string	$session_id	Session ID
+	 * @return	bool
+	 */
+	public function destroy($session_id)
+	{
+		if (isset($this->_memcached, $this->_lock_key))
+		{
+			$this->_memcached->delete($this->_key_prefix.$session_id);
+			$this->_cookie_destroy();
+			return $this->_success;
+		}
+
+		return $this->_fail();
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Garbage Collector
+	 *
+	 * Deletes expired sessions
+	 *
+	 * @param	int 	$maxlifetime	Maximum lifetime of sessions
+	 * @return	bool
+	 */
+	public function gc($maxlifetime)
+	{
+		// Not necessary, Memcached takes care of that.
+		return $this->_success;
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Get lock
+	 *
+	 * Acquires an (emulated) lock.
+	 *
+	 * @param	string	$session_id	Session ID
+	 * @return	bool
+	 */
+	protected function _get_lock($session_id)
+	{
+		// PHP 7 reuses the SessionHandler object on regeneration,
+		// so we need to check here if the lock key is for the
+		// correct session ID.
+		if ($this->_lock_key === $this->_key_prefix.$session_id.':lock')
+		{
+			if ( ! $this->_memcached->replace($this->_lock_key, time(), 300))
+			{
+				return ($this->_memcached->getResultCode() === Memcached::RES_NOTFOUND)
+					? $this->_memcached->set($this->_lock_key, time(), 300)
+					: FALSE;
+			}
+		}
+
+		// 30 attempts to obtain a lock, in case another request already has it
+		$lock_key = $this->_key_prefix.$session_id.':lock';
+		$attempt = 0;
+		do
+		{
+			if ($this->_memcached->get($lock_key))
+			{
+				sleep(1);
+				continue;
+			}
+
+			if ( ! $this->_memcached->set($lock_key, time(), 300))
+			{
+				log_message('error', 'Session: Error while trying to obtain lock for '.$this->_key_prefix.$session_id);
+				return FALSE;
+			}
+
+			$this->_lock_key = $lock_key;
+			break;
+		}
+		while (++$attempt < 30);
+
+		if ($attempt === 30)
+		{
+			log_message('error', 'Session: Unable to obtain lock for '.$this->_key_prefix.$session_id.' after 30 attempts, aborting.');
+			return FALSE;
+		}
+
+		$this->_lock = TRUE;
+		return TRUE;
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Release lock
+	 *
+	 * Releases a previously acquired lock
+	 *
+	 * @return	bool
+	 */
+	protected function _release_lock()
+	{
+		if (isset($this->_memcached, $this->_lock_key) && $this->_lock)
+		{
+			if ( ! $this->_memcached->delete($this->_lock_key) && $this->_memcached->getResultCode() !== Memcached::RES_NOTFOUND)
+			{
+				log_message('error', 'Session: Error while trying to free lock for '.$this->_lock_key);
+				return FALSE;
+			}
+
+			$this->_lock_key = NULL;
+			$this->_lock = FALSE;
+		}
+
+		return TRUE;
+	}
+}
diff --git a/system/libraries/Session/drivers/Session_redis_driver.php b/system/libraries/Session/drivers/Session_redis_driver.php
new file mode 100644
index 000000000..e220a2951
--- /dev/null
+++ b/system/libraries/Session/drivers/Session_redis_driver.php
@@ -0,0 +1,395 @@
+<?php
+/**
+ * CodeIgniter
+ *
+ * An open source application development framework for PHP
+ *
+ * This content is released under the MIT License (MIT)
+ *
+ * Copyright (c) 2014 - 2017, British Columbia Institute of Technology
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ * @package	CodeIgniter
+ * @author	EllisLab Dev Team
+ * @copyright	Copyright (c) 2008 - 2014, EllisLab, Inc. (https://ellislab.com/)
+ * @copyright	Copyright (c) 2014 - 2017, British Columbia Institute of Technology (http://bcit.ca/)
+ * @license	http://opensource.org/licenses/MIT	MIT License
+ * @link	https://codeigniter.com
+ * @since	Version 3.0.0
+ * @filesource
+ */
+defined('BASEPATH') OR exit('No direct script access allowed');
+
+/**
+ * CodeIgniter Session Redis Driver
+ *
+ * @package	CodeIgniter
+ * @subpackage	Libraries
+ * @category	Sessions
+ * @author	Andrey Andreev
+ * @link	https://codeigniter.com/user_guide/libraries/sessions.html
+ */
+class CI_Session_redis_driver extends CI_Session_driver implements SessionHandlerInterface {
+
+	/**
+	 * phpRedis instance
+	 *
+	 * @var	Redis
+	 */
+	protected $_redis;
+
+	/**
+	 * Key prefix
+	 *
+	 * @var	string
+	 */
+	protected $_key_prefix = 'ci_session:';
+
+	/**
+	 * Lock key
+	 *
+	 * @var	string
+	 */
+	protected $_lock_key;
+
+	/**
+	 * Key exists flag
+	 *
+	 * @var bool
+	 */
+	protected $_key_exists = FALSE;
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Class constructor
+	 *
+	 * @param	array	$params	Configuration parameters
+	 * @return	void
+	 */
+	public function __construct(&$params)
+	{
+		parent::__construct($params);
+
+		if (empty($this->_config['save_path']))
+		{
+			log_message('error', 'Session: No Redis save path configured.');
+		}
+		elseif (preg_match('#(?:tcp://)?([^:?]+)(?:\:(\d+))?(\?.+)?#', $this->_config['save_path'], $matches))
+		{
+			isset($matches[3]) OR $matches[3] = ''; // Just to avoid undefined index notices below
+			$this->_config['save_path'] = array(
+				'host' => $matches[1],
+				'port' => empty($matches[2]) ? NULL : $matches[2],
+				'password' => preg_match('#auth=([^\s&]+)#', $matches[3], $match) ? $match[1] : NULL,
+				'database' => preg_match('#database=(\d+)#', $matches[3], $match) ? (int) $match[1] : NULL,
+				'timeout' => preg_match('#timeout=(\d+\.\d+)#', $matches[3], $match) ? (float) $match[1] : NULL
+			);
+
+			preg_match('#prefix=([^\s&]+)#', $matches[3], $match) && $this->_key_prefix = $match[1];
+		}
+		else
+		{
+			log_message('error', 'Session: Invalid Redis save path format: '.$this->_config['save_path']);
+		}
+
+		if ($this->_config['match_ip'] === TRUE)
+		{
+			$this->_key_prefix .= $_SERVER['REMOTE_ADDR'].':';
+		}
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Open
+	 *
+	 * Sanitizes save_path and initializes connection.
+	 *
+	 * @param	string	$save_path	Server path
+	 * @param	string	$name		Session cookie name, unused
+	 * @return	bool
+	 */
+	public function open($save_path, $name)
+	{
+		if (empty($this->_config['save_path']))
+		{
+			return $this->_fail();
+		}
+
+		$redis = new Redis();
+		if ( ! $redis->connect($this->_config['save_path']['host'], $this->_config['save_path']['port'], $this->_config['save_path']['timeout']))
+		{
+			log_message('error', 'Session: Unable to connect to Redis with the configured settings.');
+		}
+		elseif (isset($this->_config['save_path']['password']) && ! $redis->auth($this->_config['save_path']['password']))
+		{
+			log_message('error', 'Session: Unable to authenticate to Redis instance.');
+		}
+		elseif (isset($this->_config['save_path']['database']) && ! $redis->select($this->_config['save_path']['database']))
+		{
+			log_message('error', 'Session: Unable to select Redis database with index '.$this->_config['save_path']['database']);
+		}
+		else
+		{
+			$this->_redis = $redis;
+			return $this->_success;
+		}
+
+		return $this->_fail();
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Read
+	 *
+	 * Reads session data and acquires a lock
+	 *
+	 * @param	string	$session_id	Session ID
+	 * @return	string	Serialized session data
+	 */
+	public function read($session_id)
+	{
+		if (isset($this->_redis) && $this->_get_lock($session_id))
+		{
+			// Needed by write() to detect session_regenerate_id() calls
+			$this->_session_id = $session_id;
+
+			$session_data = $this->_redis->get($this->_key_prefix.$session_id);
+
+			is_string($session_data)
+				? $this->_key_exists = TRUE
+				: $session_data = '';
+
+			$this->_fingerprint = md5($session_data);
+			return $session_data;
+		}
+
+		return $this->_fail();
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Write
+	 *
+	 * Writes (create / update) session data
+	 *
+	 * @param	string	$session_id	Session ID
+	 * @param	string	$session_data	Serialized session data
+	 * @return	bool
+	 */
+	public function write($session_id, $session_data)
+	{
+		if ( ! isset($this->_redis, $this->_lock_key))
+		{
+			return $this->_fail();
+		}
+		// Was the ID regenerated?
+		elseif ($session_id !== $this->_session_id)
+		{
+			if ( ! $this->_release_lock() OR ! $this->_get_lock($session_id))
+			{
+				return $this->_fail();
+			}
+
+			$this->_key_exists = FALSE;
+			$this->_session_id = $session_id;
+		}
+
+		$this->_redis->setTimeout($this->_lock_key, 300);
+		if ($this->_fingerprint !== ($fingerprint = md5($session_data)) OR $this->_key_exists === FALSE)
+		{
+			if ($this->_redis->set($this->_key_prefix.$session_id, $session_data, $this->_config['expiration']))
+			{
+				$this->_fingerprint = $fingerprint;
+				$this->_key_exists = TRUE;
+				return $this->_success;
+			}
+
+			return $this->_fail();
+		}
+
+		return ($this->_redis->setTimeout($this->_key_prefix.$session_id, $this->_config['expiration']))
+			? $this->_success
+			: $this->_fail();
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Close
+	 *
+	 * Releases locks and closes connection.
+	 *
+	 * @return	bool
+	 */
+	public function close()
+	{
+		if (isset($this->_redis))
+		{
+			try {
+				if ($this->_redis->ping() === '+PONG')
+				{
+					$this->_release_lock();
+					if ($this->_redis->close() === FALSE)
+					{
+						return $this->_fail();
+					}
+				}
+			}
+			catch (RedisException $e)
+			{
+				log_message('error', 'Session: Got RedisException on close(): '.$e->getMessage());
+			}
+
+			$this->_redis = NULL;
+			return $this->_success;
+		}
+
+		return $this->_success;
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Destroy
+	 *
+	 * Destroys the current session.
+	 *
+	 * @param	string	$session_id	Session ID
+	 * @return	bool
+	 */
+	public function destroy($session_id)
+	{
+		if (isset($this->_redis, $this->_lock_key))
+		{
+			if (($result = $this->_redis->delete($this->_key_prefix.$session_id)) !== 1)
+			{
+				log_message('debug', 'Session: Redis::delete() expected to return 1, got '.var_export($result, TRUE).' instead.');
+			}
+
+			$this->_cookie_destroy();
+			return $this->_success;
+		}
+
+		return $this->_fail();
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Garbage Collector
+	 *
+	 * Deletes expired sessions
+	 *
+	 * @param	int 	$maxlifetime	Maximum lifetime of sessions
+	 * @return	bool
+	 */
+	public function gc($maxlifetime)
+	{
+		// Not necessary, Redis takes care of that.
+		return $this->_success;
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Get lock
+	 *
+	 * Acquires an (emulated) lock.
+	 *
+	 * @param	string	$session_id	Session ID
+	 * @return	bool
+	 */
+	protected function _get_lock($session_id)
+	{
+		// PHP 7 reuses the SessionHandler object on regeneration,
+		// so we need to check here if the lock key is for the
+		// correct session ID.
+		if ($this->_lock_key === $this->_key_prefix.$session_id.':lock')
+		{
+			return $this->_redis->setTimeout($this->_lock_key, 300);
+		}
+
+		// 30 attempts to obtain a lock, in case another request already has it
+		$lock_key = $this->_key_prefix.$session_id.':lock';
+		$attempt = 0;
+		do
+		{
+			if (($ttl = $this->_redis->ttl($lock_key)) > 0)
+			{
+				sleep(1);
+				continue;
+			}
+
+			if ( ! $this->_redis->setex($lock_key, 300, time()))
+			{
+				log_message('error', 'Session: Error while trying to obtain lock for '.$this->_key_prefix.$session_id);
+				return FALSE;
+			}
+
+			$this->_lock_key = $lock_key;
+			break;
+		}
+		while (++$attempt < 30);
+
+		if ($attempt === 30)
+		{
+			log_message('error', 'Session: Unable to obtain lock for '.$this->_key_prefix.$session_id.' after 30 attempts, aborting.');
+			return FALSE;
+		}
+		elseif ($ttl === -1)
+		{
+			log_message('debug', 'Session: Lock for '.$this->_key_prefix.$session_id.' had no TTL, overriding.');
+		}
+
+		$this->_lock = TRUE;
+		return TRUE;
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Release lock
+	 *
+	 * Releases a previously acquired lock
+	 *
+	 * @return	bool
+	 */
+	protected function _release_lock()
+	{
+		if (isset($this->_redis, $this->_lock_key) && $this->_lock)
+		{
+			if ( ! $this->_redis->delete($this->_lock_key))
+			{
+				log_message('error', 'Session: Error while trying to free lock for '.$this->_lock_key);
+				return FALSE;
+			}
+
+			$this->_lock_key = NULL;
+			$this->_lock = FALSE;
+		}
+
+		return TRUE;
+	}
+
+}
diff --git a/system/libraries/Session/drivers/index.html b/system/libraries/Session/drivers/index.html
new file mode 100644
index 000000000..b702fbc39
--- /dev/null
+++ b/system/libraries/Session/drivers/index.html
@@ -0,0 +1,11 @@
+<!DOCTYPE html>
+<html>
+<head>
+	<title>403 Forbidden</title>
+</head>
+<body>
+
+<p>Directory access is forbidden.</p>
+
+</body>
+</html>
diff --git a/system/libraries/Session/index.html b/system/libraries/Session/index.html
new file mode 100644
index 000000000..b702fbc39
--- /dev/null
+++ b/system/libraries/Session/index.html
@@ -0,0 +1,11 @@
+<!DOCTYPE html>
+<html>
+<head>
+	<title>403 Forbidden</title>
+</head>
+<body>
+
+<p>Directory access is forbidden.</p>
+
+</body>
+</html>