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Dariusz Debowczyk's Session Class

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World Wide Web Server edited this page Jul 4, 2012 · 9 revisions

As of version 1.7.2 CodeIgniter's built in session class still has problems setting cookies on Internet Explorer 6,7, and 8. If you run into this problem, one possible solution is replacing the CI's session class with Dariusz Debowczyk's session class.

Dariusz's class uses PHP's built-in session-handling routines which work without issue on all known browsers.

Some CI uberfans will be quick to point out, however, that PHP's native session functions store information in the server's /tmp directory. This can be insecure if the server is hosted on a domain with other hostile users. There are ways to work around this. First of all, you can tell php to save it's session data in a different directory. This can be done on the apache web server via an .htaccess file, or in the php code itself by using ini_set(). This [url=http://www.google.com/search?hl=en&q=php+save_path+session+.htaccess&aq=f&oq;=&aqi;=]Google Search[/url] can get you started in the right direction.

[code] <?php if ( ! defined('BASEPATH')) exit('No direct script access allowed'); //> /**

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

/**

  • 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 = (6060243652); }

      // 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); } 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 */ [/code]

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