3 files changed, 56 insertions, 1 deletions

diff --git a/lib/SimpleSAML/Session.php b/lib/SimpleSAML/Session.php
index 6ab6834..153478a 100644
--- a/lib/SimpleSAML/Session.php
+++ b/lib/SimpleSAML/Session.php
@@ -377,6 +377,23 @@ class SimpleSAML_Session
         }
     }
 
+
+    /**
+     * Save the current session and clean any left overs that could interfere with the normal application behaviour.
+     *
+     * Use this method if you are using PHP sessions in your application *and* in SimpleSAMLphp, *after* you are done
+     * using SimpleSAMLphp and before trying to access your application's session again.
+     */
+    public function cleanup()
+    {
+        $this->save();
+        $sh = SimpleSAML_SessionHandler::getSessionHandler();
+        if ($sh instanceof SimpleSAML_SessionHandlerPHP) {
+            $sh->restorePrevious();
+        }
+    }
+
+
     /**
      * Mark this session as dirty.
      *
diff --git a/lib/SimpleSAML/SessionHandler.php b/lib/SimpleSAML/SessionHandler.php
index 8d14c09..23d826f 100644
--- a/lib/SimpleSAML/SessionHandler.php
+++ b/lib/SimpleSAML/SessionHandler.php
@@ -23,7 +23,7 @@ abstract class SimpleSAML_SessionHandler
      *
      * @var SimpleSAML_SessionHandler
      */
-    private static $sessionHandler = null;
+    protected static $sessionHandler = null;
 
 
     /**
diff --git a/lib/SimpleSAML/SessionHandlerPHP.php b/lib/SimpleSAML/SessionHandlerPHP.php
index 9126eab..09f7063 100644
--- a/lib/SimpleSAML/SessionHandlerPHP.php
+++ b/lib/SimpleSAML/SessionHandlerPHP.php
@@ -74,9 +74,47 @@ class SimpleSAML_SessionHandlerPHP extends SimpleSAML_SessionHandler
         $savepath = $config->getString('session.phpsession.savepath', null);
         if (!empty($savepath)) {
             session_save_path($savepath);
+        }
+    }
 
 
+    /**
+     * Restore a previously-existing session.
+     *
+     * Use this method to restore a previous PHP session existing before SimpleSAMLphp initialized its own session.
+     *
+     * WARNING: do not use this method directly, unless you know what you are doing. Calling this method directly,
+     * outside of SimpleSAML_Session, could cause SimpleSAMLphp's session to be lost or mess the application's one. The
+     * session must always be saved properly before calling this method. If you don't understand what this is about,
+     * don't use this method.
+     */
+    public function restorePrevious()
+    {
+        if (empty($this->previous_session)) {
+            return; // nothing to do here
         }
+
+        // close our own session
+        session_write_close();
+
+        session_name($this->previous_session['name']);
+        session_set_cookie_params(
+            $this->previous_session['cookie_params']['lifetime'],
+            $this->previous_session['cookie_params']['path'],
+            $this->previous_session['cookie_params']['domain'],
+            $this->previous_session['cookie_params']['secure'],
+            $this->previous_session['cookie_params']['httponly']
+        );
+        session_id($this->previous_session['id']);
+        $this->previous_session = array();
+        session_start();
+
+        /*
+         * At this point, we have restored a previously-existing session, so we can't continue to use our session here.
+         * Therefore, we need to load our session again in case we need it. We remove this handler from the parent
+         * class so that the handler is initialized again if we ever need to do something with the session.
+         */
+        parent::$sessionHandler = null;
     }