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<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
/**
* CodeIgniter
*
* An open source application development framework for PHP 5.2.4 or newer
*
* NOTICE OF LICENSE
*
* Licensed under the Open Software License version 3.0
*
* This source file is subject to the Open Software License (OSL 3.0) that is
* bundled with this package in the files license.txt / license.rst. It is
* also available through the world wide web at this URL:
* http://opensource.org/licenses/OSL-3.0
* If you did not receive a copy of the license and are unable to obtain it
* through the world wide web, please send an email to
* licensing@ellislab.com so we can send you a copy immediately.
*
* @package CodeIgniter
* @author EllisLab Dev Team
* @copyright Copyright (c) 2008 - 2012, EllisLab, Inc. (http://ellislab.com/)
* @license http://opensource.org/licenses/OSL-3.0 Open Software License (OSL 3.0)
* @link http://codeigniter.com
* @since Version 1.0
* @filesource
*/

/**
* Handle race condition during session_id updates.
* - Keep the old session id around in case we have to handle race
* conditions.
*
* session table changes (mysql):
* ALTER TABLE `sessions` ADD COLUMN `old_session_id` VARCHAR(40) DEFAULT NULL COMMENT 'old session id' AFTER `user_data`,
* ADD INDEX `old_session_id`(`old_session_id`);
* DELETE FROM `sessions`;
*/

/**
* Session Class
*
* @package CodeIgniter
* @subpackage Libraries
* @category Sessions
* @author EllisLab Dev Team
* @link http://codeigniter.com/user_guide/libraries/sessions.html
*/
class CI_Session {

/**
* Whether to encrypt the session cookie
*
* @var bool
*/
public $sess_encrypt_cookie = FALSE;

/**
* Whether to use to the database for session storage
*
* @var bool
*/
public $sess_use_database = FALSE;

/**
* Name of the database table in which to store sessions
*
* @var string
*/
public $sess_table_name = '';

/**
* Length of time (in seconds) for sessions to expire
*
* @var int
*/
public $sess_expiration = 7200;

/**
* Whether to kill session on close of browser window
*
* @var bool
*/
public $sess_expire_on_close = FALSE;

/**
* Whether to match session on ip address
*
* @var bool
*/
public $sess_match_ip = FALSE;

/**
* Whether to match session on user-agent
*
* @var bool
*/
public $sess_match_useragent = TRUE;

/**
* Name of session cookie
*
* @var string
*/
public $sess_cookie_name = 'ci_session';

/**
* Session cookie prefix
*
* @var string
*/
public $cookie_prefix = '';

/**
* Session cookie path
*
* @var string
*/
public $cookie_path = '';

/**
* Session cookie domain
*
* @var string
*/
public $cookie_domain = '';

/**
* Whether to set the cookie only on HTTPS connections
*
* @var bool
*/
public $cookie_secure = FALSE;

/**
* Whether cookie should be allowed only to be sent by the server
*
* @var bool
*/
public $cookie_httponly = FALSE;

/**
* Interval at which to update session
*
* @var int
*/
public $sess_time_to_update = 300;

/**
* Key with which to encrypt the session cookie
*
* @var string
*/
public $encryption_key = '';

/**
* String to indicate flash data cookies
*
* @var string
*/
public $flashdata_key = 'flash';

/**
* Timezone to use for the current time
*
* @var string
*/
public $time_reference = 'local';


/**
* Session data
*
* @var array
*/
public $userdata = array();

/**
* Reference to CodeIgniter instance
*
* @var object
*/
public $CI;

/**
* Current time
*
* @var int
*/
public $now;

/**
* Session Constructor
*
* The constructor runs the session routines automatically
* whenever the class is instantiated.
*
* @param array
* @return void
*/
public function __construct($params = array())
{
log_message('debug', 'Session Class Initialized');

// Set the super object to a local variable for use throughout the class
$this->CI =& get_instance();

// Set all the session preferences, which can either be set
// manually via the $params array above or via the config file
foreach (array('sess_encrypt_cookie', 'sess_use_database', 'sess_table_name', 'sess_expiration', 'sess_expire_on_close', 'sess_match_ip', 'sess_match_useragent', 'sess_cookie_name', 'cookie_path', 'cookie_domain', 'cookie_secure', 'cookie_httponly', 'sess_time_to_update', 'time_reference', 'cookie_prefix', 'encryption_key') as $key)
{
$this->$key = isset($params[$key]) ? $params[$key] : $this->CI->config->item($key);
}

if ($this->encryption_key === '')
{
show_error('In order to use the Session class you are required to set an encryption key in your config file.');
}

// Load the string helper so we can use the strip_slashes() function
$this->CI->load->helper('string');

// Do we need encryption? If so, load the encryption class
if ($this->sess_encrypt_cookie === TRUE)
{
$this->CI->load->library('encrypt');
}

// Are we using a database? If so, load it
if ($this->sess_use_database === TRUE && $this->sess_table_name !== '')
{
$this->CI->load->database();
}

// Set the "now" time. Can either be GMT or server time, based on the
// config prefs. We use this to set the "last activity" time
$this->now = $this->_get_time();

// Set the session length. If the session expiration is
// set to zero we'll set the expiration two years from now.
if ($this->sess_expiration === 0)
{
$this->sess_expiration = (60*60*24*365*2);
}

// Set the cookie name
$this->sess_cookie_name = $this->cookie_prefix.$this->sess_cookie_name;

// Run the Session routine. If a session doesn't exist we'll
// create a new one. If it does, we'll update it.
if ( ! $this->sess_read())
{
$this->sess_create();
}
else
{
$this->sess_update();
}

// Delete 'old' flashdata (from last request)
$this->_flashdata_sweep();

// Mark all new flashdata as old (data will be deleted before next request)
$this->_flashdata_mark();

// Delete expired sessions if necessary
$this->_sess_gc();

log_message('debug', 'Session routines successfully run');
}

// --------------------------------------------------------------------

/**
* Fetch the current session data if it exists
*
* @return bool
*/
public function sess_read()
{
// Fetch the cookie
$session = $this->CI->input->cookie($this->sess_cookie_name);

// No cookie? Goodbye cruel world!...
if ($session === NULL)
{
log_message('debug', 'A session cookie was not found.');
return FALSE;
}

// Decrypt the cookie data
if ($this->sess_encrypt_cookie === TRUE)
{
$session = $this->CI->encrypt->decode($session);
}
else
{
// encryption was not used, so we need to check the md5 hash
$hash = substr($session, strlen($session)-32); // get last 32 chars
$session = substr($session, 0, strlen($session)-32);

// Does the md5 hash match? This is to prevent manipulation of session data in userspace
if ($hash !== md5($session.$this->encryption_key))
{
log_message('error', 'The session cookie data did not match what was expected. This could be a possible hacking attempt.');
$this->sess_destroy();
return FALSE;
}
}

// Unserialize the session array
$session = $this->_unserialize($session);

// Is the session data we unserialized an array with the correct format?
if ( ! is_array($session) OR ! isset($session['session_id'], $session['ip_address'], $session['user_agent'], $session['last_activity']))
{
$this->sess_destroy();
return FALSE;
}

// Is the session current?
if (($session['last_activity'] + $this->sess_expiration) < $this->now)
{
$this->sess_destroy();
return FALSE;
}

// Does the IP match?
if ($this->sess_match_ip === TRUE && $session['ip_address'] !== $this->CI->input->ip_address())
{
$this->sess_destroy();
return FALSE;
}

// Does the User Agent Match?
if ($this->sess_match_useragent === TRUE && trim($session['user_agent']) !== trim(substr($this->CI->input->user_agent(), 0, 120)))
{
$this->sess_destroy();
return FALSE;
}

// Is there a corresponding session in the DB?
if ($this->sess_use_database === TRUE)
{
// Search both session_id and old_session_id fields for the
// incoming session id.
//
// Manually create the OR condition because it causes the least
// disturbance to existing code.
//
// Store the session id from the cookie so that we can see if we
// came in through the old session id later.
$this->CI->db->where( '(session_id = ' . $this->CI->db->escape($session['session_id']) . ' OR old_session_id = ' . $this->CI->db->escape($session['session_id']) . ')' );
$this->cookie_session_id = $session['session_id'];

if ($this->sess_match_ip === TRUE)
{
$this->CI->db->where('ip_address', $session['ip_address']);
}

if ($this->sess_match_useragent === TRUE)
{
$this->CI->db->where('user_agent', $session['user_agent']);
}

$query = $this->CI->db->limit(1)->get($this->sess_table_name);

// No result? Kill it!
if ($query->num_rows() === 0)
{
$this->sess_destroy();
return FALSE;
}

// Is there custom data? If so, add it to the main session array
$row = $query->row();
if ( ! empty($row->user_data))
{
$custom_data = $this->_unserialize($row->user_data);

if (is_array($custom_data))
{
foreach ($custom_data as $key => $val)
{
$session[$key] = $val;
}
}
}

// Pull the session_id from the database to populate the curent
// session id because the old one is stale.
//
// Pull the old_session_id from the database so that we can
// compare the current (cookie) session id against it later.
$session['session_id'] = $row->session_id;
$session['old_session_id'] = $row->old_session_id;
}

// Session is valid!
$this->userdata = $session;
unset($session);

return TRUE;
}

// --------------------------------------------------------------------

/**
* Write the session data
*
* @return void
*/
public function sess_write()
{
// Are we saving custom data to the DB? If not, all we do is update the cookie
if ($this->sess_use_database === FALSE)
{
$this->_set_cookie();
return;
}

// set the custom userdata, the session data we will set in a second
$custom_userdata = $this->userdata;
$cookie_userdata = array();

// Before continuing, we need to determine if there is any custom data to deal with.
// Let's determine this by removing the default indexes to see if there's anything left in the array
// and set the session data while we're at it
foreach (array('session_id','ip_address','user_agent','last_activity') as $val)
{
unset($custom_userdata[$val]);
$cookie_userdata[$val] = $this->userdata[$val];
}

// old_session_id has its own field, but it doesn't need to go into
// a cookie because we'll always retrieve it from the database.
unset($custom_userdata['old_session_id']);

// Did we find any custom data? If not, we turn the empty array into a string
// since there's no reason to serialize and store an empty array in the DB
if (count($custom_userdata) === 0)
{
$custom_userdata = '';
}
else
{
// Serialize the custom data array so we can store it
$custom_userdata = $this->_serialize($custom_userdata);
}

// Run the update query
$this->CI->db->where('session_id', $this->userdata['session_id']);
$this->CI->db->update($this->sess_table_name, array('last_activity' => $this->userdata['last_activity'], 'user_data' => $custom_userdata));

// Write the cookie. Notice that we manually pass the cookie data array to the
// _set_cookie() function. Normally that function will store $this->userdata, but
// in this case that array contains custom data, which we do not want in the cookie.
$this->_set_cookie($cookie_userdata);
}

// --------------------------------------------------------------------

/**
* Create a new session
*
* @return void
*/
public function sess_create()
{
$sessid = '';
do
{
$sessid .= mt_rand(0, mt_getrandmax());
}
while (strlen($sessid) < 32);

// To make the session ID even more secure we'll combine it with the user's IP
$sessid .= $this->CI->input->ip_address();

$this->userdata = array(
'session_id' => md5(uniqid($sessid, TRUE)),
'ip_address' => $this->CI->input->ip_address(),
'user_agent' => substr($this->CI->input->user_agent(), 0, 120),
'last_activity' => $this->now,
'user_data' => ''
);

// Save the data to the DB if needed
if ($this->sess_use_database === TRUE)
{
$this->CI->db->query($this->CI->db->insert_string($this->sess_table_name, $this->userdata));
}

// Write the cookie
$this->_set_cookie();
}

// --------------------------------------------------------------------

/**
* Update an existing session
*
* @return void
*/
public function sess_update()
{
// We only update the session every five minutes by default
if (($this->userdata['last_activity'] + $this->sess_time_to_update) >= $this->now)
{
return;
}

// _set_cookie() will handle this for us if we aren't using database sessions
// by pushing all userdata to the cookie.
$cookie_data = NULL;

// Don't need to regenerate the session if we came in by indexing to
// the old_session_id, but send out the cookie anyway to make sure
// that the client has a copy of the new cookie.
//
// Do an isset check first in case we're not using the database to
// store extra data. The old_session_id field only exists in the
// database.
if ((isset($this->userdata['old_session_id'])) &&
($this->cookie_session_id === $this->userdata['old_session_id']))
{
// set cookie explicitly to only have our session data
$cookie_data = array();
foreach (array('session_id','ip_address','user_agent','last_activity') as $val)
{
$cookie_data[$val] = $this->userdata[$val];
}

$this->_set_cookie($cookie_data);
return;
}
/* Changing the session ID during an AJAX call causes problems,
* so we'll only update our last_activity
*/
elseif ($this->CI->input->is_ajax_request())
{
$this->userdata['last_activity'] = $this->now;

// Update the session ID and last_activity field in the DB if needed
if ($this->sess_use_database === TRUE)
{
// set cookie explicitly to only have our session data
$cookie_data = array();
foreach (array('session_id','ip_address','user_agent','last_activity') as $val)
{
$cookie_data[$val] = $this->userdata[$val];
}

$this->CI->db->query($this->CI->db->update_string($this->sess_table_name,
array('last_activity' => $this->userdata['last_activity']),
array('session_id' => $this->userdata['session_id'])));
}

return $this->_set_cookie($cookie_data);
}

// Save the old session id so we know which record to
// update in the database if we need it
$old_sessid = $this->userdata['session_id'];
$new_sessid = '';
do
{
$new_sessid .= mt_rand(0, mt_getrandmax());
}
while (strlen($new_sessid) < 32);

// To make the session ID even more secure we'll combine it with the user's IP
$new_sessid .= $this->CI->input->ip_address();

// Turn it into a hash and update the session data array
$this->userdata['session_id'] = $new_sessid = md5(uniqid($new_sessid, TRUE));
$this->userdata['last_activity'] = $this->now;

// Update the session ID and last_activity field in the DB if needed
if ($this->sess_use_database === TRUE)
{
// set cookie explicitly to only have our session data
$cookie_data = array();
foreach (array('session_id','ip_address','user_agent','last_activity') as $val)
{
$cookie_data[$val] = $this->userdata[$val];
}

// Save the old session id into the old_session_id field so that
// we can reference it later.
//
// Rewrite the cookie's session id if there are zero affected rows
// because that means that another request changed the database
// under the current request. In this case, we want to return a
// value consistent with the previous request. Reread immediately
// after the update call here to minimize timing problems. This
// should be in a transaction for databases that support them.
//
// Also rewrite the userdata so that future calls to sess_write
// will output the correct cookie data.
$this->CI->db->query($this->CI->db->update_string($this->sess_table_name, array('last_activity' => $this->now, 'session_id' => $new_sessid, 'old_session_id' => $old_sessid), array('session_id' => $old_sessid)));

if ($this->CI->db->affected_rows() === 0)
{
$this->CI->db->where('old_session_id', $this->cookie_session_id);
$query = $this->CI->db->get($this->sess_table_name);

// We've lost track of the session if there are no results, so
// don't set a cookie and just return.
if ($query->num_rows() == 0)
{
return;
}

$row = $query->row();
foreach (array('session_id','ip_address','user_agent','last_activity') as $val)
{
$this->userdata[$val] = $row->$val;
$cookie_data[$val] = $this->userdata[$val];
}

// Set the request session id to the old session id so that we
// won't try to regenerate the cookie again on this request --
// just in case sess_update is ever called again (which it
// shouldn't be).
$this->cookie_session_id = $this->userdata['old_session_id'];
}

}

// Write the cookie
$this->_set_cookie($cookie_data);
}

// --------------------------------------------------------------------

/**
* Destroy the current session
*
* @return void
*/
public function sess_destroy()
{
// Kill the session DB row
if ($this->sess_use_database === TRUE && isset($this->userdata['session_id']))
{
$this->CI->db->where('session_id', $this->userdata['session_id']);
$this->CI->db->delete($this->sess_table_name);
}

// Kill the cookie
setcookie(
$this->sess_cookie_name,
addslashes(serialize(array())),
($this->now - 31500000),
$this->cookie_path,
$this->cookie_domain,
0
);

// Kill session data
$this->userdata = array();
}

// --------------------------------------------------------------------

/**
* Fetch a specific item from the session array
*
* @param string
* @return string
*/
public function userdata($item)
{
return isset($this->userdata[$item]) ? $this->userdata[$item] : NULL;
}

// --------------------------------------------------------------------

/**
* Fetch all session data
*
* @return array
*/
public function all_userdata()
{
return $this->userdata;
}

// --------------------------------------------------------------------------

/**
* Fetch all flashdata
*
* @return array
*/
public function all_flashdata()
{
$out = array();

// loop through all userdata
foreach ($this->all_userdata() as $key => $val)
{
// if it contains flashdata, add it
if (strpos($key, 'flash:old:') !== FALSE)
{
$out[$key] = $val;
}
}
return $out;
}

// --------------------------------------------------------------------

/**
* Add or change data in the "userdata" array
*
* @param mixed
* @param string
* @return void
*/
public function set_userdata($newdata = array(), $newval = '')
{
if (is_string($newdata))
{
$newdata = array($newdata => $newval);
}

if (count($newdata) > 0)
{
foreach ($newdata as $key => $val)
{
$this->userdata[$key] = $val;
}
}

$this->sess_write();
}

// --------------------------------------------------------------------

/**
* Delete a session variable from the "userdata" array
*
* @param array
* @return void
*/
public function unset_userdata($newdata = array())
{
if (is_string($newdata))
{
$newdata = array($newdata => '');
}

if (count($newdata) > 0)
{
foreach ($newdata as $key => $val)
{
unset($this->userdata[$key]);
}
}

$this->sess_write();
}

// ------------------------------------------------------------------------

/**
* Add or change flashdata, only available
* until the next request
*
* @param mixed
* @param string
* @return void
*/
public function set_flashdata($newdata = array(), $newval = '')
{
if (is_string($newdata))
{
$newdata = array($newdata => $newval);
}

if (count($newdata) > 0)
{
foreach ($newdata as $key => $val)
{
$this->set_userdata($this->flashdata_key.':new:'.$key, $val);
}
}
}

// ------------------------------------------------------------------------

/**
* Keeps existing flashdata available to next request.
*
* @param string
* @return void
*/
public function keep_flashdata($key)
{
// 'old' flashdata gets removed. Here we mark all
// flashdata as 'new' to preserve it from _flashdata_sweep()
// Note the function will return NULL if the $key
// provided cannot be found
$value = $this->userdata($this->flashdata_key.':old:'.$key);

$this->set_userdata($this->flashdata_key.':new:'.$key, $value);
}

// ------------------------------------------------------------------------

/**
* Fetch a specific flashdata item from the session array
*
* @param string
* @return string
*/
public function flashdata($key)
{
return $this->userdata($this->flashdata_key.':old:'.$key);
}

// ------------------------------------------------------------------------

/**
* Identifies flashdata as 'old' for removal
* when _flashdata_sweep() runs.
*
* @return void
*/
protected function _flashdata_mark()
{
$userdata = $this->all_userdata();
foreach ($userdata as $name => $value)
{
$parts = explode(':new:', $name);
if (is_array($parts) && count($parts) === 2)
{
$this->set_userdata($this->flashdata_key.':old:'.$parts[1], $value);
$this->unset_userdata($name);
}
}
}

// ------------------------------------------------------------------------

/**
* Removes all flashdata marked as 'old'
*
* @return void
*/
protected function _flashdata_sweep()
{
$userdata = $this->all_userdata();
foreach ($userdata as $key => $value)
{
if (strpos($key, ':old:'))
{
$this->unset_userdata($key);
}
}

}

// --------------------------------------------------------------------

/**
* Get the "now" time
*
* @return string
*/
protected function _get_time()
{
if ($this->time_reference === 'local' OR $this->time_reference === date_default_timezone_get())
{
return time();
}

$datetime = new DateTime('now', new DateTimeZone($this->time_reference));
sscanf($datetime->format('j-n-Y G:i:s'), '%d-%d-%d %d:%d:%d', $day, $month, $year, $hour, $minute, $second);

return mktime($hour, $minute, $second, $month, $day, $year);
}

// --------------------------------------------------------------------

/**
* Write the session cookie
*
* @param mixed
* @return void
*/
protected function _set_cookie($cookie_data = NULL)
{
if (is_null($cookie_data))
{
$cookie_data = $this->userdata;
}

// Serialize the userdata for the cookie
$cookie_data = $this->_serialize($cookie_data);

if ($this->sess_encrypt_cookie === TRUE)
{
$cookie_data = $this->CI->encrypt->encode($cookie_data);
}
else
{
// if encryption is not used, we provide an md5 hash to prevent userside tampering
$cookie_data = $cookie_data.md5($cookie_data.$this->encryption_key);
}

$expire = ($this->sess_expire_on_close === TRUE) ? 0 : $this->sess_expiration + time();

// Set the cookie
setcookie(
$this->sess_cookie_name,
$cookie_data,
$expire,
$this->cookie_path,
$this->cookie_domain,
$this->cookie_secure,
$this->cookie_httponly
);
}

// --------------------------------------------------------------------

/**
* Serialize an array
*
* This function first converts any slashes found in the array to a temporary
* marker, so when it gets unserialized the slashes will be preserved
*
* @param array
* @return string
*/
protected function _serialize($data)
{
if (is_array($data))
{
array_walk_recursive($data, array(&$this, '_escape_slashes'));
}
elseif (is_string($data))
{
$data = str_replace('\\', '{{slash}}', $data);
}
return serialize($data);
}

/**
* Escape slashes
*
* This function converts any slashes found into a temporary marker
*
* @param string
* @param string
* @return void
*/
protected function _escape_slashes(&$val, $key)
{
if (is_string($val))
{
$val = str_replace('\\', '{{slash}}', $val);
}
}

// --------------------------------------------------------------------

/**
* Unserialize
*
* This function unserializes a data string, then converts any
* temporary slash markers back to actual slashes
*
* @param array
* @return string
*/
protected function _unserialize($data)
{
$data = @unserialize(strip_slashes(trim($data)));

if (is_array($data))
{
array_walk_recursive($data, array(&$this, '_unescape_slashes'));
return $data;
}

return is_string($data) ? str_replace('{{slash}}', '\\', $data) : $data;
}

// --------------------------------------------------------------------

/**
* Unescape slashes
*
* This function converts any slash markers back into actual slashes
*
* @param string
* @param string
* @return void
*/
protected function _unescape_slashes(&$val, $key)
{
if (is_string($val))
{
$val= str_replace('{{slash}}', '\\', $val);
}
}

// --------------------------------------------------------------------

/**
* Garbage collection
*
* This deletes expired session rows from database
* if the probability percentage is met
*
* @return void
*/
protected function _sess_gc()
{
if ($this->sess_use_database !== TRUE)
{
return;
}

$probability = ini_get('session.gc_probability');
$divisor = ini_get('session.gc_divisor');

srand(time());
if ((mt_rand(0, $divisor) / $divisor) < $probability)
{
$expire = $this->now - $this->sess_expiration;

$this->CI->db->where('last_activity < '.$expire);
$this->CI->db->delete($this->sess_table_name);

log_message('debug', 'Session garbage collection performed.');
}
}

}

/* End of file Session.php */
/* Location: ./system/libraries/Session.php */
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