system/libraries/Session/drivers/Session_memcached_driver.php
<?php
/**
* CodeIgniter
*
* An open source application development framework for PHP
*
* This content is released under the MIT License (MIT)
*
* Copyright (c) 2019 - 2022, CodeIgniter Foundation
*
* 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 - 2019, British Columbia Institute of Technology (https://bcit.ca/)
* @copyright Copyright (c) 2019 - 2022, CodeIgniter Foundation (https://codeigniter.com/)
* @license https://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/userguide3/libraries/sessions.html
*/
class CI_Session_memcached_driver extends CI_Session_driver implements CI_Session_driver_interface {
/**
* 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 $this->_failure;
}
foreach ($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->_failure;
}
$this->php5_validate_id();
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->_failure;
}
// ------------------------------------------------------------------------
/**
* 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 $this->_failure;
}
// Was the ID regenerated?
elseif ($session_id !== $this->_session_id)
{
if ( ! $this->_release_lock() OR ! $this->_get_lock($session_id))
{
return $this->_failure;
}
$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->_failure;
}
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 $this->_failure;
}
// ------------------------------------------------------------------------
/**
* Close
*
* Releases locks and closes connection.
*
* @return bool
*/
public function close()
{
if (isset($this->_memcached))
{
$this->_release_lock();
if ( ! $this->_memcached->quit())
{
return $this->_failure;
}
$this->_memcached = NULL;
return $this->_success;
}
return $this->_failure;
}
// ------------------------------------------------------------------------
/**
* 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->_failure;
}
// ------------------------------------------------------------------------
/**
* 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;
}
// --------------------------------------------------------------------
/**
* Update Timestamp
*
* Update session timestamp without modifying data
*
* @param string $id Session ID
* @param string $data Unknown & unused
* @return bool
*/
public function updateTimestamp($id, $unknown)
{
return $this->_memcached->touch($this->_key_prefix.$id, $this->_config['expiration']);
}
// --------------------------------------------------------------------
/**
* Validate ID
*
* Checks whether a session ID record exists server-side,
* to enforce session.use_strict_mode.
*
* @param string $id Session ID
* @return bool
*/
public function validateId($id)
{
$this->_memcached->get($this->_key_prefix.$id);
return ($this->_memcached->getResultCode() === Memcached::RES_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)
? $this->_memcached->add($this->_lock_key, time(), 300)
: FALSE;
}
return TRUE;
}
// 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;
}
$method = ($this->_memcached->getResultCode() === Memcached::RES_NOTFOUND) ? 'add' : 'set';
if ( ! $this->_memcached->$method($lock_key, time(), 300))
{
log_message('error', 'Session: Error while trying to obtain lock for '.$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;
}
}