Session native php Codeigniter

<?php  if (!defined('BASEPATH')) exit('No direct script access allowed');

/**
* Session class using native PHP session features and hardened against session fixation.
*
* @package     CodeIgniter
* @subpackage  Libraries
* @category    Sessions
* @author      Dariusz Debowczyk
* @link        http://www.codeigniter.com/user_guide/libraries/sessions.html
*/
class MY_Session extends CI_Session {

    public $flash_key = 'flash'; // prefix for "flash" variables (eg. flash:new:message)

    public $object;

    public $userdata = array();

    public $sess_name = 'SGISESSID'; //name session

    /**
     * Class constructor
     * @return type
     */
    public function __construct()
    {
        $this->object =& get_instance();
        log_message('debug', "Native_session Class Initialized");
        $this->_sess_run();
    }

   /**
    * Regenerates session id
    * @return type
    */
    public function regenerate_id()
    {
        // copy old session data, including its id
        $old_session_id = session_id();
        $old_session_data = $_SESSION;

        // regenerate session id and store it
        session_regenerate_id();
        $new_session_id = session_id();

        // switch to the old session and destroy its storage
        session_id($old_session_id);
        session_destroy();

        // switch back to the new session id and send the cookie
        session_id($new_session_id);
        session_start();

        // restore the old session data into the new session
        $_SESSION = $old_session_data;

        // update the session creation time
        $_SESSION['regenerated'] = time();

        // session_write_close() patch based on this thread
        // http://www.codeigniter.com/forums/viewthread/1624/
        // there is a question mark ?? as to side affects

        // end the current session and store session data.
        session_write_close();
    }

   /**
    * Destroys the session and erases session storage
    * @return type
    */
    public function destroy()
    {
        unset($_SESSION);
        if ( isset( $_COOKIE[session_name()] ) )
        {
            setcookie(session_name(), '', time()-42000, '/');
        }
        session_destroy();
    }

   /**
    * Just call destroy method for compatibility
    * @return type
    */
    public function sess_destroy()
    {
        $this->destroy();
    }

    /**
     * Reads given session attribute value
     * @param type $item
     * @return type
     */
    public function userdata($item)
    {
        if($item == 'session_id') //added for backward-compatibility
        {
            return session_id();
        }
        else
        {
            return ( ! isset($_SESSION[$item]) ) ? false : $_SESSION[$item];
        }
    }

   /**
    * Sets session attributes to the given values
    * @param type $newdata
    * @param type $newval
    * @return type
    */
    public function set_userdata($newdata = array(), $newval = '')
    {
        if (is_string($newdata))
        {
            $newdata = array($newdata => $newval);
        }

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

   /**
    * Erases given session attributes
    * @param type $newdata
    * @return type
    */
    public function unset_userdata($newdata = array())
    {
        if (is_string($newdata))
        {
            $newdata = array($newdata => '');
        }

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

   /**
    * Starts up the session system for current request
    * @return type
    */
    public function _sess_run()
    {
        // define name session
        session_name($this->sess_name);

        $session_id_ttl = $this->object->config->item('sess_expiration');

        if (is_numeric($session_id_ttl))
        {
            if ($session_id_ttl > 0)
            {
                $this->session_id_ttl = $this->object->config->item('sess_expiration');
            }
            else
            {
                $this->session_id_ttl = (60*60*24*365*2);
            }
        }

        // define time to expire session
        session_cache_expire($this->session_id_ttl);
        session_set_cookie_params($this->session_id_ttl);

        //start session
        session_start();


        // check if session id needs regeneration
        if ( $this->_session_id_expired() )
        {
            // regenerate session id (session data stays the
            // same, but old session storage is destroyed)
            $this->regenerate_id();
        }

        // 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();

        // set userdata with $_SESSION global
        $this->userdata = $_SESSION;
    }

    /**
     * Checks if session has expired
     * @return type
     */
    public function _session_id_expired()
    {
        if ( ! isset( $_SESSION['regenerated'] ) )
        {
            $_SESSION['regenerated'] = time();
            return FALSE;
        }

        $expiry_time = time() - $this->session_id_ttl;

        if ( $_SESSION['regenerated'] <=  $expiry_time )
        {
            return TRUE;
        }

        return FALSE;
    }

   /**
    * Sets "flash" data which will be available only in next request (then it will
    * be deleted from session). You can use it to implement "Save succeeded" messages
    * after redirect.
    *
    * @param type $key
    * @param type $value
    * @return type
    */
    public function set_flashdata($key, $value)
    {
        $flash_key = $this->flash_key.':new:'.$key;
        $this->set_userdata($flash_key, $value);
    }

   /**
    * Keeps existing "flash" data available to next request.
    * @param type $key
    * @return type
    */
    public function keep_flashdata($key)
    {
        $old_flash_key = $this->flash_key.':old:'.$key;
        $value = $this->userdata($old_flash_key);

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

   /**
    * Returns "flash" data for the given key.
    * @param type $key
    * @return type
    */
    public function flashdata($key)
    {
        $flash_key = $this->flash_key.':old:'.$key;
        return $this->userdata($flash_key);
    }

   /**
    * PRIVATE: Internal method - marks "flash" session attributes as 'old'
    * @return type
    */
    public function _flashdata_mark()
    {
        foreach ($_SESSION as $name => $value)
        {
            $parts = explode(':new:', $name);
            if (is_array($parts) && count($parts) == 2)
            {
                $new_name = $this->flash_key.':old:'.$parts[1];
                $this->set_userdata($new_name, $value);
                $this->unset_userdata($name);
            }
        }
    }

   /**
    * PRIVATE: Internal method - removes "flash" session marked as 'old'
    * @return type
    */
    public function _flashdata_sweep()
    {
        foreach ($_SESSION as $name => $value)
        {
            $parts = explode(':old:', $name);
            if (is_array($parts) && count($parts) == 2 && $parts[0] == $this->flash_key)
            {
                $this->unset_userdata($name);
            }
        }
    }

}

/* End of file MY_Session.php */
/* Location: /../libraries/MY_Session.php */