17

DB2 Session

sidh edited this page 2012-10-08 07:23:05 -07:00

Table of Contents

• Improvements include
• Changelog
• Version 1.0
• Final Note
• Now for the code... Enjoy.

This Mod was inspired by the original DB Session by Dready. Last updated on 2 April 2008.

Created in March 2008, it takes the new version of CodeIgniter's 1.6.1 Session class and combines DB Session with some newly revised functions.

Improvements include

• Flashdata was not optimised for database storing. The number of queries when using the "flashdata" commands have been reduced significantly.
• Whenever new data has been stored, a new session_id is assigned to improve security.
• General improvements that have boosted performance.
• Object model is exactly the same, so its easy to replace your main existing Session class with this one.

Changelog

Version 1.0

• Initial release

Final Note

There may be some final improvements and they will be logged on this wiki page. Any criticism to help improve this mod is welcome.

Discussion thread

Now for the code... Enjoy.

<?php  if (!defined('BASEPATH')) exit('No direct script access allowed');
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP 4.3.2 or newer
 *
 * DB2 Session
 *
 * @package        CodeIgniter
 * @author        ExpressionEngine Dev Team
 * @copyright    Copyright (c) 2006, EllisLab, Inc.
 * @license        http://codeigniter.com/user_guide/license.html
 * @link        http://codeigniter.com
 * @since        Version 1.0
 * @filesource
 *
 * ************* DB2 Session VERSION *****************
 * @original author        ExpressionEngine Dev Team
 * @inspired by            Dready, Original DB Session mod - http://dready.jexiste.fr/dotclear/index.php?2006/09/13/19-reworked-session-handler-for-code-igniter
 * @author                Flash
 * @created                03/2008
 * @last updated        02/04/2008
 * @mod version            1.0
 */

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

/**
 * Session Class
 *
 * @package        CodeIgniter
 * @subpackage    Libraries
 * @category    Sessions
 * @author        ExpressionEngine Dev Team
 * @link        http://codeigniter.com/user_guide/libraries/sessions.html
 */
class DB2_Session {

    var $CI;
    var $now;
    var $encryption        = TRUE;
    var $use_database    = FALSE;
    var $session_table    = FALSE;
    var $sess_length    = 7200;
    var $sess_cookie    = 'ci_session';
    var $userdata        = array();
    var $gc_probability    = 5;
    var $flashdata_key     = 'flash';
    var $time_to_update    = 300;

    /**
     * Session Constructor
     *
     * The constructor runs the session routines automatically
     * whenever the class is instantiated.
     */
    function DB2_Session()
    {
        $this->CI =& get_instance();

        log_message('debug', "Session Class Initialized");
        $this->sess_run();
    }

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

    /**
     * Run the session routines
     *
     * @access    public
     * @return    void
     */
    function sess_run()
    {
        /*
         *  Set the "now" time
         *
         * It can either set to GMT or time(). The pref
         * is set in the config file.  If the developer
         * is doing any sort of time localization they
         * might want to set the session time to GMT so
         * they can offset the "last_activity" time
         * based on each user's locale.
         *
         */

        if (is_numeric($this->CI->config->item('sess_time_to_update')))
        {
            $this->time_to_update = $this->CI->config->item('sess_time_to_update');
        }

        if (strtolower($this->CI->config->item('time_reference')) == 'gmt')
        {
            $now = time();
            $this->now = mktime(gmdate("H", $now), gmdate("i", $now), gmdate("s", $now), gmdate("m", $now), gmdate("d", $now), gmdate("Y", $now));

            if (strlen($this->now) < 10)
            {
                $this->now = time();
                log_message('error', 'The session class could not set a proper GMT timestamp so the local time() value was used.');
            }
        }
        else
        {
            $this->now = time();
        }

        /*
         *  Set the session length
         *
         * If the session expiration is set to zero in
         * the config file we'll set the expiration
         * two years from now.
         *
         */
        $expiration = $this->CI->config->item('sess_expiration');

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

        // Do we need encryption?
        $this->encryption = $this->CI->config->item('sess_encrypt_cookie');

        if ($this->encryption == TRUE)
        {
            $this->CI->load->library('encrypt');
        }

        // Are we using a database?
        if ($this->CI->config->item('sess_use_database') === TRUE AND $this->CI->config->item('sess_table_name') != '')
        {
            $this->use_database = TRUE;
            $this->session_table = $this->CI->config->item('sess_table_name');
            $this->CI->load->database();
        }

        // Set the cookie name
        if ($this->CI->config->item('sess_cookie_name') != FALSE)
        {
            $this->sess_cookie = $this->CI->config->item('cookie_prefix').$this->CI->config->item('sess_cookie_name');
        }

        /*
         *  Fetch the current session
         *
         * If a session doesn't exist we'll create
         * a new one.  If it does, we'll update it.
         *
         */
        if ( ! $this->sess_read())
        {
            $this->sess_create();
        }
        else
        {
            // We only update the session every five minutes
            if (($this->userdata['last_activity'] + $this->time_to_update) < $this->now)
            {
                $this->sess_update();
            }
        }

        // Delete expired sessions if necessary
        if ($this->use_database === TRUE)
        {
            $this->sess_gc();
        }

        // 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();
    }

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

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

        if ($session_id === FALSE)
        {
            log_message('debug', 'A session cookie was not found.');
            return FALSE;
        }

        // Is there a corresponding session in the DB?
        $this->CI->db->where('session_id', $session_id);

        // session should not have expired
        $this->CI->db->where('last_activity >', ($this->now - $this->sess_length) );

        // Does the IP Match?
        if ($this->CI->config->item('sess_match_ip') == TRUE)
        {
            $this->CI->db->where('ip_address', $this->CI->input->ip_address());
        }

        // Does the User Agent Match?
        if ($this->CI->config->item('sess_match_useragent') == TRUE)
        {
            $this->CI->db->where('user_agent', substr(htmlspecialchars((string) $this->CI->input->user_agent()), 0, 50));
        }

        $query = $this->CI->db->get($this->session_table);

        if ($query->num_rows() == 0)
        {
            $this->sess_destroy();
            return FALSE;
        }
        else
        {
            $row = $query->row();
            if (($row->last_activity + $this->sess_length) < $this->now)
            {
                $this->CI->db->where('session_id', $session_id);
                $this->CI->db->delete($this->session_table);
                $this->sess_destroy();
                return FALSE;
            } else {
                $session = @unserialize($row->session_data);
                if ( ! is_array($session) ) {
                    $session = array();
                }
                $session['session_id'] = $session_id;
                $session['ip_address'] = $row->ip_address;
                $session['user_agent'] = $row->user_agent;
                $session['last_activity'] = $row->last_activity;
            }
        }

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

        return TRUE;
    }

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

    /**
     * Write the session cookie
     *
     * @access    public
     * @return    void
     */
    function sess_write()
    {
        setcookie(
                    $this->sess_cookie,
                    $this->userdata['session_id'],
                    $this->sess_length + time(),
                    $this->CI->config->item('cookie_path'),
                    $this->CI->config->item('cookie_domain'),
                    0
                );
    }

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

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

        $this->userdata = array(
                            'session_id'     => md5(uniqid($sessid, TRUE)),
                            'ip_address'     => $this->CI->input->ip_address(),
                            'user_agent'     => substr($this->CI->input->user_agent(), 0, 50),
                            'last_activity'    => $this->now
                            );


        $this->CI->db->query($this->CI->db->insert_string($this->session_table, $this->userdata));

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

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

    /**
     * Update an existing session
     *
     * @access    public
     * @return    void
     */
    function sess_update()
    {
        // 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'];
        $new_sessid = '';
        while (strlen($new_sessid) < 32)
        {
            $new_sessid .= mt_rand(0, mt_getrandmax());
        }
        $new_sessid = md5(uniqid($new_sessid, TRUE));

        // Update the session data in the session data array
        $this->userdata['session_id'] = $new_sessid;
        $this->userdata['last_activity'] = $this->now;

        // format query array to update database
        $ud = $this->userdata;
        $sql_ary = array(
        'session_id'    => $new_sessid,
        'last_activity' => $ud['last_activity']);

        unset($ud['session_id'], $ud['last_activity'], $ud['user_agent'], $ud['ip_address']);

        $sql_ary['session_data'] = serialize($ud);
        $this->CI->db->query($this->CI->db->update_string($this->session_table, $sql_ary, array('session_id' => $old_sessid)));

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

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

    /**
     * Destroy the current session
     *
     * @access    public
     * @return    void
     */
    function sess_destroy()
    {
        setcookie(
                    $this->sess_cookie,
                    '',
                    ($this->now - 31500000),
                    $this->CI->config->item('cookie_path'),
                    $this->CI->config->item('cookie_domain'),
                    0
                );
    }

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

    /**
     * Garbage collection
     *
     * This deletes expired session rows from database
     * if the probability percentage is met
     *
     * @access    public
     * @return    void
     */
    function sess_gc()
    {
        srand(time());
        if ((rand() % 100) < $this->gc_probability)
        {
            $expire = $this->now - $this->sess_length;

            $this->CI->db->where("last_activity < {$expire}");
            $this->CI->db->delete($this->session_table);

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

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

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

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

    /**
     * Fetch all session data
     *
     * @access    public
     * @return    mixed
     */
    function all_userdata()
    {
        return ( ! isset($this->userdata)) ? FALSE : $this->userdata;
    }

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

    /**
     * Add or change data in the "userdata" array
     *
     * @access    public
     * @param    mixed
     * @param    string
     * @return    void
     */
    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_update();
    }

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

    /**
     * Delete a session variable from the "userdata" array
     *
     * @access    array
     * @return    void
     */
    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_update();
    }

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

    /**
     * Strip slashes
     *
     * @access    public
     * @param    mixed
     * @return    mixed
     */
    function strip_slashes($vals)
    {
        if (is_array($vals))
         {
             foreach ($vals as $key=>$val)
             {
                 $vals[$key] = $this->strip_slashes($val);
             }
         }
         else
         {
             $vals = stripslashes($vals);
         }

         return $vals;
    }


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

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

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

            $this->set_userdata($new);
        }
    }

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

    /**
     * Keeps existing flashdata available to next request.
     *
     * @access    public
     * @param    string
     * @return    void
     */
    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 FALSE if the $key
        // provided cannot be found
        $old_flashdata_key = $this->flashdata_key.':old:'.$key;
        $value = $this->userdata($old_flashdata_key);

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

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

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

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

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

        // Don't update session; Is flashdata exists, _flashdata_sweep will write the new data automatically anyway
    }

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

    /**
     * Removes all flashdata marked as 'old'
     *
     * @access    private
     * @return    void
     */

    function _flashdata_sweep()
    {
        $i=0;
        $userdata = $this->all_userdata();
        foreach ($userdata as $key => $value)
        {
            if (strpos($key, ':old:'))
            {
                unset($this->userdata[$key]);
                $i++;
            }
        }

        if ($i > 0) {
            $this->sess_update();
        }
    }

}
// END Session Class
?>