Only call session_start() when reading from session

fixes #6383

library/Icinga/Authentication/Manager.php

@@ -27,7 +27,7 @@ class Manager
      * Authenticated user
      *
      * @var User
-     **/
+     */
     private $user;
 
     /**
@@ -96,25 +96,24 @@ class Manager
         );
         $this->user = $user;
         if ($persist == true) {
-            $session = Session::getSession();
-            $session->refreshId();
             $this->persistCurrentUser();
         }
     }
 
     /**
      * Writes the current user to the session
-     **/
+     */
     public function persistCurrentUser()
     {
         $session = Session::getSession();
         $session->set('user', $this->user);
         $session->write();
+        $session->refreshId();
     }
 
     /**
      * Tries to authenticate the user with the current session
-     **/
+     */
     public function authenticateFromSession()
     {
         $this->user = Session::getSession()->get('user');
@@ -189,7 +188,7 @@ class Manager
      * Returns the current user or null if no user is authenticated
      *
      * @return User
-     **/
+     */
     public function getUser()
     {
         return $this->user;
@@ -200,7 +199,7 @@ class Manager
      *
      * @return  array
      * @see     User::getGroups
-     **/
+     */
     public function getGroups()
     {
         return $this->user->getGroups();

library/Icinga/Web/Notification.php

@@ -100,8 +100,11 @@ class Notification
     {
         $session = Session::getSession();
         $msgs = $session->messages;
-        $session->messages = array();
+        if (false === empty($msgs)) {
-        $session->write();
+            $session->messages = array();
+            $session->write();
+        }
+
         return $msgs;
     }
 

library/Icinga/Web/Session/PhpSession.php

@@ -5,7 +5,7 @@
 namespace Icinga\Web\Session;
 
 use Icinga\Logger\Logger;
-use \Icinga\Exception\ConfigurationError;
+use Icinga\Exception\ConfigurationError;
 
 /**
  * Session implementation in PHP
@@ -24,21 +24,21 @@ class PhpSession extends Session
      *
      * @var bool
      */
-    private $hasBeenTouched = false;
+    protected $hasBeenTouched = false;
 
     /**
      * Name of the session
      *
      * @var string
      */
-    private $sessionName = 'Icingaweb2';
+    protected $sessionName = 'Icingaweb2';
 
     /**
      * Configuration for cookie options
      *
      * @var array
      */
-    private static $defaultCookieOptions = array(
+    protected static $defaultCookieOptions = array(
         'use_trans_sid'             => false,
         'use_cookies'               => true,
         'cookie_httponly'           => true,
@@ -82,13 +82,16 @@ class PhpSession extends Session
             throw new ConfigurationError('Can\'t save session');
         }
 
-        $this->read();
+        if ($this->exists()) {
+            // We do not want to start a new session here if there is not any
+            $this->read();
+        }
     }
 
     /**
      * Open a PHP session
      */
-    private function open()
+    protected function open()
     {
         session_name($this->sessionName);
 
@@ -171,7 +174,7 @@ class PhpSession extends Session
     /**
      * Remove session cookies
      */
-    private function clearCookies()
+    protected function clearCookies()
     {
         if (ini_get('session.use_cookies')) {
             Logger::debug('Clear session cookie');
@@ -196,5 +199,14 @@ class PhpSession extends Session
         $this->open();
         session_regenerate_id();
         session_write_close();
+        $this->hasBeenTouched = true;
+    }
+
+    /**
+     * @see Session::exists()
+     */
+    public function exists()
+    {
+        return isset($_COOKIE[$this->sessionName]);
     }
 }

library/Icinga/Web/Session/Session.php

@@ -37,6 +37,13 @@ abstract class Session extends SessionNamespace
         throw new NotImplementedError('You are required to implement write() in your session implementation');
     }
 
+    /**
+     * Return whether a session exists
+     *
+     * @return  bool
+     */
+    abstract public function exists();
+
     /**
      * Purge session
      */