MY_Session

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');
/**
 * ExiteCMS Core Session Class
 *
 * This library replaces the CodeIgniter Session class. While providing the
 * same functionality, it provides several improvements over the original:
 * - fixed session id rotation race condition with parallel requests
 * - only writes a session when explicitly asked to
 * - fixed flashdata bug that destroyed custom flashdata keys
 * - replaced 'last_update' by 'last_rotate' and 'last_write' for more accuracy
 *
 * @package     ExiteCMS
 * @subpackage  Libraries
 * @category    Libraries
 * @author      ExiteCMS Dev Team
 * @link        http://www.exitecms.org
 */

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

/**
 * This session library requires a database table with this layout:
 *
* CREATE TABLE IF NOT EXISTS  `ci_sessions` (session_id VARCHAR(40) DEFAULT '0' NOT NULL, previous_id VARCHAR(40) DEFAULT '0' NOT NULL, ip_address VARCHAR(16) DEFAULT '0' NOT NULL, user_agent VARCHAR(50) NOT NULL, last_rotate INT(10) unsigned DEFAULT 0 NOT NULL, last_write INT(10) unsigned DEFAULT 0 NOT NULL, user_data TEXT DEFAULT NULL NULL, PRIMARY KEY (session_id,previous_id));
 */

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

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

    var $sess_encrypt_cookie        = FALSE;
    var $sess_use_database          = FALSE;
    var $sess_table_name            = '';
    var $sess_expiration            = 7200;
    var $sess_expire_on_close       = FALSE;
    var $sess_match_ip              = FALSE;
    var $sess_match_useragent       = FALSE;
    var $sess_cookie_name           = 'cisession';
    var $cookie_prefix              = '';
    var $cookie_path                = '';
    var $cookie_domain              = '';
    var $cookie_secure              = FALSE;
    var $sess_time_to_update        = 300;
    var $encryption_key             = '';
    var $flashdata_key              = 'flash';
    var $time_reference             = 'time';
    var $gc_probability             = 5;
    var $userdata                   = array();
    var $CI;
    var $now;




    /**
     * Session Constructor
     *
     * The constructor runs the session routines automatically
     * whenever the class is instantiated.
     */
    function CI_Session($params = array('encryption_key' => 'x'))
    {
        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', '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 AND $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
     *
     * @access  public
     * @return  bool
     */
    function sess_read()
    {
        // Fetch the cookie
        $session = $this->CI->input->cookie($this->sess_cookie_name);

        // No cookie?  Goodbye cruel world!...
        if ($session === FALSE)
        {
            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, $this->encryption_key);
        }
        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']) OR ! isset($session['previous_id']) OR ! isset($session['ip_address']) OR ! isset($session['user_agent']) OR ! isset($session['last_rotate']) OR ! isset($session['last_write']))
        {
            $this->sess_destroy();
            return FALSE;
        }

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

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

        // Does the User Agent Match?
        if ($this->sess_match_useragent == TRUE AND trim($session['user_agent']) != trim(substr($this->CI->input->user_agent(), 0, 50)))
        {
            $this->sess_destroy();
            return FALSE;
        }

        // Is there a corresponding session in the DB?
        if ($this->sess_use_database === TRUE)
        {
            $this->CI->db->where('( session_id = "'.$session['session_id'].'" OR previous_id = "'.$session['session_id'].'")', NULL, FALSE);

            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 = $this->CI->db->get($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 = $query->row();
            if ( isset($row->user_data) )
            {
                if (  $row->user_data != '' )
                {
                    $custom_data = $this->_unserialize($row->user_data);

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

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

        return TRUE;
    }

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

    /**
     * Write the session data
     *
     * @access  public
     * @return  void
     */
    function sess_write($write = TRUE)
    {
        // Only write if specifically asked
        if ( ! $write )
        {
            return;
        }

        // 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','previous_id','ip_address','user_agent','last_rotate', 'last_write') as $val)
        {
            unset($custom_userdata[$val]);
            $cookie_userdata[$val] = $this->userdata[$val];
        }

        // 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_rotate' => $this->userdata['last_rotate'], 'last_write' => $this->now, '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.
        if ( $this->CI->db->affected_rows() )
        {
            $this->_set_cookie($cookie_userdata);
        }
    }

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

    /**
     * Create a new session
     *
     * @access  public
     * @return  void
     */
    function sess_create()
    {
        $sessid = '';

        for($i = 0; $i < 32; $i++)
        {
            $sessid .= mt_rand(0, mt_getrandmax());
        }

        // 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)),
                            'previous_id'   => '',
                            'ip_address'    => $this->CI->input->ip_address(),
                            'user_agent'    => substr($this->CI->input->user_agent(), 0, 50),
                            'last_rotate'   => $this->now,
                            'last_write'    => $this->now
                            );

        // 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
     *
     * @access  public
     * @return  void
     */
    function sess_update()
    {

        // We only update the session every five minutes by default
        if (($this->userdata['last_rotate'] + $this->sess_time_to_update) >= $this->now)
        {
            return;
        }

        // 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'];
        $new_sessid = '';
        for($i = 0; $i < 32; $i++)
        {
            $new_sessid .= mt_rand(0, mt_getrandmax());
        }

        // 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
        $new_sessid = md5(uniqid($new_sessid, TRUE));

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

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

        // 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','previous_id','ip_address','user_agent','last_rotate', 'last_write') as $val)
            {
                $cookie_data[$val] = $this->userdata[$val];
            }

            $this->CI->db->query($this->CI->db->update_string($this->sess_table_name, array('last_rotate' => $this->now, 'last_write' => $this->now, 'session_id' => $new_sessid, 'previous_id' => $old_sessid), array('session_id' => $old_sessid)));
        }

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

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

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

        // erase the userdata loaded
        $this->userdata = array();

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

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

    /**
     * Fetch a specific item from the session array
     *
     * Our version supports multi-arrays as session data
     *
     * @access  public
     * @param   string
     * @return  string
     */
    function userdata($item, $subitem = NULL)
    {
        if ( is_null($subitem) )
        {
            return ( ! isset($this->userdata[$item])) ? FALSE : $this->userdata[$item];
        }
        else
        {
            return ( ! isset($this->userdata[$item][$subitem])) ? FALSE : $this->userdata[$item][$subitem];
        }
    }

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

    /**
     * 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;
            }
        }

        if ( ! (isset($this->userdata['session_id'])))
        {
            log_message('error', "userdata: ".print_r($this->userdata, TRUE));
            log_message('error', "newdata: ".print_r($newdata, TRUE));
            log_message('error', "newval: ".$newval);
        }
        $this->sess_write();
    }

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

    /**
     * Add or change data in the "userdata" array
     *
     * set_userdata method with support for multi-dimensional arrays
     *
     * @access  public
     * @param   string
     * @param   array
     * @return  void
     */
    function set_userdata_array($arrayname = NULL, $newdata = array())
    {
        if ( ! is_null($arrayname) && is_array($newdata) )
        {
            if ( !isset($this->userdata[$arrayname]) )
            {
                $this->userdata[$arrayname] = array();
            }

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

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

    /**
     * Delete a session variable from the "userdata" array
     *
     * Our version supports multi-arrays as session data
     *
     * @access  public
     * @param   string
     * @return  string
     */
    function unset_userdata($item, $subitem = NULL)
    {
        if ( is_null($subitem) )
        {
            if (is_string($item))
            {
                $item = array($item => '');
            }

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

        if ( ! (isset($this->userdata['session_id'])))
        {

            log_message('error', "userdata: ".print_r($this->userdata, TRUE));
            log_message('error', "item: ".print_r($item, TRUE));
            log_message('error', "subitem: ".$subitem);
        }
        $this->sess_write();
    }

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

    /**
     * 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;
                $this->set_userdata($flashdata_key, $val);
            }
        }
    }

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

    /**
     * Keeps existing flashdata available to next request.
     *
     * Our version supports keeping all flashdata by not passing a key value
     *
     * @access    public
     * @param    string
     * @return    void
     */
    function keep_flashdata($key = NULL)
    {
        // Mark individual flashdata as 'new' to preserve it from _flashdata_sweep()
        if ($key !== NULL)
        {
            // '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);
        }
        else
        {
            // Mark all 'old' flashdata as 'new' (keep data from being deleted during next request)
            $userdata = $this->all_userdata();
            foreach ($userdata as $name => $value)
            {
                $parts = explode(':old:', $name);
                if (is_array($parts) && count($parts) === 2)
                {
                    $new_name = $parts[0].':new:'.$parts[1];
                    $this->set_userdata($new_name, $value);
                    $this->unset_userdata($name);
                }
            }
        }
    }

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

    /**
     * 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.
     *
     * Fix for a bug in the CI library (hardcoded use of $this->flashdata_key)
     *
     * @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 = $parts[0].':old:'.$parts[1];
                $this->set_userdata($new_name, $value);
                $this->unset_userdata($name);
            }
        }
    }

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

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

    function _flashdata_sweep()
    {
        $userdata = $this->all_userdata();
        foreach ($userdata as $key => $value)
        {
            if (strpos($key, ':old:'))
            {
                $this->unset_userdata($key);
            }
        }

    }


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

    /**
     * Get the "now" time
     *
     * @access  private
     * @return  string
     */
    function _get_time()
    {
        if (strtolower($this->time_reference) == 'gmt')
        {
            $now = time();
            $time = mktime(gmdate("H", $now), gmdate("i", $now), gmdate("s", $now), gmdate("m", $now), gmdate("d", $now), gmdate("Y", $now));
        }
        else
        {
            $time = time();
        }

        return $time;
    }

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

    /**
     * Write the session cookie
     *
     * @access  public
     * @return  void
     */
    function _set_cookie($cookie_data = NULL)
    {

        if (is_null($cookie_data))
        {
            $cookie_data = $this->userdata;
        }


        // update the last write timestamp
        $cookie_userdata['last_write'] = $this->now;

        // 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, $this->encryption_key);
        }
        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,
                    0
                );
    }

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

    /**
     * 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
     *
     * @access  private
     * @param   array
     * @return  string
     */
    function _serialize($data)
    {
        if (is_array($data))
        {
            foreach ($data as $key => $val)
            {
                if (is_string($val))
                {
                    $data[$key] = str_replace('\\', '{{slash}}', $val);
                }
            }
        }
        else
        {
            if (is_string($data))
            {
                $data = str_replace('\\', '{{slash}}', $data);
            }
        }

        return serialize($data);
    }

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

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

        if (is_array($data))
        {
            foreach ($data as $key => $val)
            {
                if (is_string($val))
                {
                    $data[$key] = str_replace('{{slash}}', '\\', $val);
                }
            }

            return $data;
        }

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

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

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

        srand(time());
        if ((rand() % 100) < $this->gc_probability)
        {
            $expire = $this->now - $this->sess_expiration;

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

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


}
// END Session Class

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