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<?php
/**
* CodeIgniter
*
* An open source application development framework for PHP
*
* This content is released under the MIT License (MIT)
*
* Copyright (c) 2014 - 2018, 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 - 2018, 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();
}
}
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