Session.php

Go to the documentation of this file.

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP 4.3.2 or newer
 *
 * @package             CodeIgniter
 * @author              ExpressionEngine Dev Team
 * @copyright   Copyright (c) 2008, EllisLab, Inc.
 * @license             http://codeigniter.com/user_guide/license.html
 * @link                http://codeigniter.com
 * @since               Version 1.0
 * @filesource
 */

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

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

        var $sess_encrypt_cookie                = FALSE;
        var $sess_use_database                  = FALSE;
        var $sess_table_name                    = '';
        var $sess_expiration                    = 7200;
        var $sess_match_ip                              = FALSE;
        var $sess_match_useragent               = TRUE;
        var $sess_cookie_name                   = 'ci_session';
        var $cookie_prefix                              = '';
        var $cookie_path                                = '';
        var $cookie_domain                              = '';
        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())
        {
                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_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);
                }               
        
                // 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      void
         */
        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);
                }
                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($session['ip_address']) OR ! isset($session['user_agent']) OR ! isset($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 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']);
                                        
                        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) AND $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 is valid!
                $this->userdata = $session;
                unset($session);
                
                return TRUE;
        }
        
        // --------------------------------------------------------------------
        
        /**
         * Write the session data
         *
         * @access      public
         * @return      void
         */
        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];
                }
                
                // 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
         *
         * @access      public
         * @return      void
         */
        function sess_create()
        {       
                $sessid = '';
                while (strlen($sessid) < 32)
                {
                        $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)),
                                                        'ip_address'    => $this->CI->input->ip_address(),
                                                        'user_agent'    => substr($this->CI->input->user_agent(), 0, 50),
                                                        'last_activity' => $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_activity'] + $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'];
                $new_sessid = '';
                while (strlen($new_sessid) < 32)
                {
                        $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['session_id'] = $new_sessid;
                $this->userdata['last_activity'] = $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','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->now, 'session_id' => $new_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']);
                        $this->CI->db->delete($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
                                );
        }
        
        // --------------------------------------------------------------------
        
        /**
         * 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_write();
        }
        
        // --------------------------------------------------------------------
        
        /**
         * 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_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.
         *
         * @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];
                                $this->set_userdata($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;
                }
        
                // 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);
                }
                
                // Set the cookie
                setcookie(
                                        $this->sess_cookie_name,
                                        $cookie_data,
                                        $this->sess_expiration + time(),
                                        $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)
                        {
                                $data[$key] = str_replace('\\', '{{slash}}', $val);
                        }
                }
                else
                {
                        $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)
                        {
                                $data[$key] = str_replace('{{slash}}', '\\', $val);
                        }
                        
                        return $data;
                }
                
                return str_replace('{{slash}}', '\\', $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;
                        
                        $this->CI->db->where("last_activity < {$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: ./system/libraries/Session.php */