Improve session validity check with changing auth cookies; reduce writes to DB; better phpdoc

config/main.inc.php.dist

@@ -206,13 +206,12 @@ $rcmail_config['skin_include_php'] = false;
 // must be greater than 'keep_alive'/60
 $rcmail_config['session_lifetime'] = 10;
 
+// session domain: .example.org
+$rcmail_config['session_domain'] = '';
+
 // check client IP in session athorization
 $rcmail_config['ip_check'] = false;
 
-// Use an additional frequently changing cookie to athenticate user sessions.
-// There have been problems reported with this feature.
-$rcmail_config['double_auth'] = false;
-
 // this key is used to encrypt the users imap password which is stored
 // in the session record (and the client cookie if remember password is enabled).
 // please provide a string of exactly 24 chars.
@@ -292,9 +291,6 @@ $rcmail_config['line_length'] = 72;
 // send plaintext messages as format=flowed
 $rcmail_config['send_format_flowed'] = true;
 
-// session domain: .example.org
-$rcmail_config['session_domain'] = '';
-
 // don't allow these settings to be overriden by the user
 $rcmail_config['dont_override'] = array();
 

index.php

@@ -98,7 +98,7 @@ if ($RCMAIL->task == 'login' && $RCMAIL->action == 'login') {
     $RCMAIL->session->regenerate_id();
 
     // send auth cookie if necessary
-    $RCMAIL->authenticate_session();
+    $RCMAIL->session->set_auth_cookie();
 
     // log successful login
     rcmail_log_login();
@@ -141,7 +141,7 @@ else if ($RCMAIL->task == 'logout' && isset($_SESSION['user_id'])) {
 
 // check session and auth cookie
 else if ($RCMAIL->task != 'login' && $_SESSION['user_id'] && $RCMAIL->action != 'send') {
-  if (!$RCMAIL->authenticate_session()) {
+  if (!$RCMAIL->session->check_auth()) {
     $OUTPUT->show_message('sessionerror', 'error');
     $RCMAIL->kill_session();
   }

program/include/rcmail.php

@@ -599,10 +599,8 @@ class rcmail
       session_start();
 
     // set initial session vars
-    if (!isset($_SESSION['auth_time'])) {
-      $_SESSION['auth_time'] = time();
+    if (!$_SESSION['user_id'])
       $_SESSION['temp'] = true;
-    }
   }
 
 
@@ -624,6 +622,9 @@ class rcmail
       $keep_alive = max(60, $keep_alive);
       $this->session->set_keep_alive($keep_alive);
     }
+    
+    $this->session->set_secret($this->config->get('des_key') . $_SERVER['HTTP_USER_AGENT']);
+    $this->session->set_ip_check($this->config->get('ip_check'));
   }
 
 
@@ -998,41 +999,6 @@ class rcmail
   }
 
 
-  /**
-   * Check the auth hash sent by the client against the local session credentials
-   *
-   * @return boolean True if valid, False if not
-   */
-  function authenticate_session()
-  {
-    // advanced session authentication
-    if ($this->config->get('double_auth')) {
-      $now = time();
-      $valid = ($_COOKIE['sessauth'] == $this->get_auth_hash(session_id(), $_SESSION['auth_time']) ||
-                $_COOKIE['sessauth'] == $this->get_auth_hash(session_id(), $_SESSION['last_auth']));
-
-      // renew auth cookie every 5 minutes (only for GET requests)
-      if (!$valid || ($_SERVER['REQUEST_METHOD']!='POST' && $now - $_SESSION['auth_time'] > 300)) {
-        $_SESSION['last_auth'] = $_SESSION['auth_time'];
-        $_SESSION['auth_time'] = $now;
-        rcmail::setcookie('sessauth', $this->get_auth_hash(session_id(), $now), 0);
-      }
-    }
-    else {
-      $valid = $this->config->get('ip_check') ? $_SERVER['REMOTE_ADDR'] == $this->session->get_ip() : true;
-    }
-
-    // check session filetime
-    $lifetime = $this->config->get('session_lifetime');
-    $sess_ts = $this->session->get_ts();
-    if (!empty($lifetime) && !empty($sess_ts) && $sess_ts + $lifetime*60 < time()) {
-      $valid = false;
-    }
-
-    return $valid;
-  }
-
-
   /**
    * Destroy session data and remove cookie
    */
@@ -1040,9 +1006,8 @@ class rcmail
   {
     $this->plugins->exec_hook('session_destroy');
 
-    $this->session->remove();
-    $_SESSION = array('language' => $this->user->language, 'auth_time' => time(), 'temp' => true);
-    rcmail::setcookie('sessauth', '-del-', time() - 60);
+    $this->session->kill();
+    $_SESSION = array('language' => $this->user->language, 'temp' => true);
     $this->user->reset();
   }
 
@@ -1056,7 +1021,7 @@ class rcmail
 
     // on logout action we're not connected to imap server
     if (($config['logout_purge'] && !empty($config['trash_mbox'])) || $config['logout_expunge']) {
-      if (!$this->authenticate_session())
+      if (!$this->session->check_auth())
         return;
 
       $this->imap_connect();

program/include/rcube_session.php

@@ -5,7 +5,7 @@
  | program/include/rcube_session.php                                     |
  |                                                                       |
  | This file is part of the Roundcube Webmail client                     |
- | Copyright (C) 2005-2010, The Roundcube Dev Team                       |
+ | Copyright (C) 2005-2011, The Roundcube Dev Team                       |
  | Licensed under the GNU GPL                                            |
  |                                                                       |
  | PURPOSE:                                                              |
@@ -31,12 +31,17 @@ class rcube_session
 {
   private $db;
   private $ip;
+  private $start;
   private $changed;
   private $unsets = array();
   private $gc_handlers = array();
-  private $start;
+  private $cookiename = 'roundcube_sessauth';
   private $vars = false;
   private $key;
+  private $now;
+  private $prev;
+  private $secret = '';
+  private $ip_check = false;
   private $keep_alive = 0;
 
   /**
@@ -47,6 +52,12 @@ class rcube_session
     $this->db = $db;
     $this->lifetime = $lifetime;
     $this->start = microtime(true);
+    $this->ip = $_SERVER['REMOTE_ADDR'];
+
+    // valid time range is now - 1/2 lifetime to now + 1/2 lifetime
+    $now = time();
+    $this->now = $now - ($now % ($this->lifetime / 2));
+    $this->prev = $this->now - ($this->lifetime / 2);
 
     // set custom functions for PHP session management
     session_set_save_handler(
@@ -93,7 +104,14 @@ class rcube_session
   }
 
 
-  // save session data
+  /**
+   * Save session data.
+   * handler for session_read()
+   *
+   * @param string Session ID
+   * @param string Serialized session vars
+   * @return boolean True on success
+   */
   public function write($key, $vars)
   {
     $ts = microtime(true);
@@ -118,28 +136,22 @@ class rcube_session
       else
         $newvars = $vars;
 
-      if (!$this->lifetime) {
-        $timeout = 600;
-      }
-      else if ($this->keep_alive>0) {
-        $timeout = min($this->lifetime * 0.5, $this->lifetime - $this->keep_alive);
-      } else {
-        $timeout = 0;
-      }
-
-      if (!($newvars === $oldvars) || ($ts - $this->changed > $timeout)) {
+      if ($newvars !== $oldvars) {
         $this->db->query(
-          sprintf("UPDATE %s SET vars = ?, changed = %s WHERE sess_id = ?",
+          sprintf("UPDATE %s SET vars=?, changed=%s WHERE sess_id=?",
             get_table_name('session'), $now),
           base64_encode($newvars), $key);
       }
+      else if ($ts - $this->changed > $this->lifetime / 2) {
+        $this->db->query("UPDATE ".get_table_name('session')." SET changed=$now WHERE sess_id=?", $key);
+      }
     }
     else {
       $this->db->query(
         sprintf("INSERT INTO %s (sess_id, vars, ip, created, changed) ".
           "VALUES (?, ?, ?, %s, %s)",
           get_table_name('session'), $now, $now),
-        $key, base64_encode($vars), (string)$_SERVER['REMOTE_ADDR']);
+        $key, base64_encode($vars), (string)$this->ip);
     }
 
     $this->unsets = array();
@@ -147,7 +159,12 @@ class rcube_session
   }
 
 
-  // handler for session_destroy()
+  /**
+   * Handler for session_destroy()
+   *
+   * @param string Session ID
+   * @return boolean True on success
+   */
   public function destroy($key)
   {
     $this->db->query(
@@ -158,7 +175,12 @@ class rcube_session
   }
 
 
-  // garbage collecting function
+  /**
+   * Garbage collecting function
+   *
+   * @param string Session lifetime in seconds
+   * @return boolean True on success
+   */
   public function gc($maxlifetime)
   {
     // just delete all expired sessions
@@ -173,7 +195,11 @@ class rcube_session
   }
 
 
-  // registering additional garbage collector functions
+  /**
+   * Register additional garbage collector functions
+   *
+   * @param mixed Callback function
+   */
   public function register_gc_handler($func_name)
   {
     if ($func_name && !in_array($func_name, $this->gc_handlers))
@@ -181,33 +207,41 @@ class rcube_session
   }
 
 
+  /**
+   * Generate and set new session id
+   */
   public function regenerate_id()
   {
+    // delete old session record
+    $this->destroy(session_id());
+    $this->vars = false;
+
     $randval = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
 
     for ($random = '', $i=1; $i <= 32; $i++) {
       $random .= substr($randval, mt_rand(0,(strlen($randval) - 1)), 1);
     }
 
-    // use md5 value for id or remove capitals from string $randval
-    $random = md5($random);
-
-    // delete old session record
-    $this->destroy(session_id());
-
-    session_id($random);
+    // use md5 value for id
+    $this->key = md5($random);
+    session_id($this->key);
 
     $cookie   = session_get_cookie_params();
     $lifetime = $cookie['lifetime'] ? time() + $cookie['lifetime'] : 0;
 
-    rcmail::setcookie(session_name(), $random, $lifetime);
+    rcmail::setcookie(session_name(), $this->key, $lifetime);
 
     return true;
   }
 
 
-  // unset session variable
-  public function remove($var=NULL)
+  /**
+   * Unset a session variable
+   *
+   * @param string Varibale name
+   * @return boolean True on success
+   */
+  public function remove($var=null)
   {
     if (empty($var))
       return $this->destroy(session_id());
@@ -218,8 +252,19 @@ class rcube_session
     return true;
   }
   
+  /**
+   * Kill this session
+   */
+  public function kill()
+  {
+    $this->destroy(session_id());
+    rcmail::setcookie($this->cookiename, '-del-', time() - 60);
+  }
+
 
-  // serialize session data
+  /**
+   * Serialize session data
+   */
   private function serialize($vars)
   {
     $data = '';
@@ -232,8 +277,10 @@ class rcube_session
   }
 
 
-  // unserialize session data
-  // http://www.php.net/manual/en/function.session-decode.php#56106
+  /**
+   * Unserialize session data
+   * http://www.php.net/manual/en/function.session-decode.php#56106
+   */
   private function unserialize($str)
   {
     $str = (string)$str;
@@ -318,26 +365,99 @@ class rcube_session
     return unserialize( 'a:' . $items . ':{' . $serialized . '}' );
   }
 
+  /**
+   * Setter for keep_alive interval
+   */
   public function set_keep_alive($keep_alive)
   {
     $this->keep_alive = $keep_alive;
   }
 
+  /**
+   * Getter for keep_alive interval
+   */
   public function get_keep_alive()
   {
     return $this->keep_alive;
   }
 
-  // getter for private variables
-  public function get_ts()
+  /**
+   * Getter for remote IP saved with this session
+   */
+  public function get_ip()
   {
-    return $this->changed;
+    return $this->ip;
   }
   
-  // getter for private variables
-  public function get_ip()
+  /**
+   * Setter for cookie encryption secret
+   */
+  function set_secret($secret)
   {
-    return $this->ip;
+    $this->secret = $secret;
+  }
+
+
+  /**
+   * Enable/disable IP check
+   */
+  function set_ip_check($check)
+  {
+    $this->ip_check = $check;
+  }
+  
+  /**
+   * Setter for the cookie name used for session cookie
+   */
+  function set_cookiename($cookiename)
+  {
+    if ($cookiename)
+      $this->cookiename = $cookiename;
+  }
+
+
+  /**
+   * Check session authentication cookie
+   *
+   * @return boolean True if valid, False if not
+   */
+  function check_auth()
+  {
+    $this->cookie = $_COOKIE[$this->cookiename];
+    $result = $this->ip_check ? $_SERVER['REMOTE_ADDR'] == $this->ip : true;
+
+    if ($result && $this->_mkcookie($this->now) != $this->cookie) {
+      // Check if using id from previous time slot
+      if ($this->_mkcookie($this->prev) == $this->cookie)
+        $this->set_auth_cookie();
+      else
+        $result = false;
+    }
+
+    return $result;
+  }
+
+
+  /**
+   * Set session authentication cookie
+   */
+  function set_auth_cookie()
+  {
+    $this->cookie = $this->_mkcookie($this->now);
+    rcmail::setcookie($this->cookiename, $this->cookie, 0);
+    $_COOKIE[$this->cookiename] = $this->cookie;
+  }
+
+
+  /**
+   * Create session cookie from session data
+   *
+   * @param int Time slot to use
+   */
+  function _mkcookie($timeslot)
+  {
+    $auth_string = "$this->key,$this->secret,$timeslot";
+    return "S" . (function_exists('sha1') ? sha1($auth_string) : md5($auth_string));
   }
 
 }