Bugfixes: the PHP session handler only fetches the cookie configuration...

Bugfixes: the PHP session handler only fetches the cookie configuration parameters if session_id() returns a non-empty ID. This won't happen if the application initialized a session previously, hijacking the session and causing all kinds of trouble. Instead, we need to detect if there's an active session, save its parameters and close it. After closing it, we can name a new session and set the cookie parameters.

lib/SimpleSAML/SessionHandlerPHP.php

@@ -19,6 +19,18 @@ class SimpleSAML_SessionHandlerPHP extends SimpleSAML_SessionHandler
      */
     protected $cookie_name;
 
+    /**
+     * An associative array containing the details of a session existing previously to creating or loading one with this
+     * session handler. The keys of the array will be:
+     *
+     *   - id: the ID of the session, as returned by session_id().
+     *   - name: the name of the session, as returned by session_name().
+     *   - cookie_params: the parameters of the session cookie, as returned by session_get_cookie_params().
+     *
+     * @var array
+     */
+    private $previous_session = array();
+
 
     /**
      * Initialize the PHP session handling. This constructor is protected because it should only be called from
@@ -29,35 +41,41 @@ class SimpleSAML_SessionHandlerPHP extends SimpleSAML_SessionHandler
         // call the parent constructor in case it should become necessary in the future
         parent::__construct();
 
-        /* Initialize the php session handling.
-         *
-         * If session_id() returns a blank string, then we need to call session start. Otherwise the session is already
-         * started, and we should avoid calling session_start().
-         */
-        if (session_id() === '') {
-            $config = SimpleSAML_Configuration::getInstance();
-
-            $params = $this->getCookieParams();
-
-            session_set_cookie_params(
-                $params['lifetime'],
-                $params['path'],
-                $params['domain'],
-                $params['secure'],
-                $params['httponly']
-            );
+        if (session_status() === PHP_SESSION_ACTIVE) {
+            /*
+             * We shouldn't have a session at this point, so it might be an application session. Save the details to
+             * retrieve it later and commit.
+             */
+            $this->previous_session['cookie_params'] = session_get_cookie_params();
+            $this->previous_session['id'] = session_id();
+            $this->previous_session['name'] = session_name();
+            session_write_close();
+        }
+
+        $config = SimpleSAML_Configuration::getInstance();
+
+        $this->cookie_name = $config->getString('session.phpsession.cookiename', null);
+        if (!empty($this->cookie_name)) {
+            session_name($this->cookie_name);
+        } else {
+            $this->cookie_name = session_name();
+        }
+
+        $params = $this->getCookieParams();
+
+        session_set_cookie_params(
+            $params['lifetime'],
+            $params['path'],
+            $params['domain'],
+            $params['secure'],
+            $params['httponly']
+        );
+
+        $savepath = $config->getString('session.phpsession.savepath', null);
+        if (!empty($savepath)) {
+            session_save_path($savepath);
 
-            $this->cookie_name = $config->getString('session.phpsession.cookiename', null);
-            if (!empty($this->cookie_name)) {
-                session_name($this->cookie_name);
-            } else {
-                $this->cookie_name = session_name();
-            }
 
-            $savepath = $config->getString('session.phpsession.savepath', null);
-            if (!empty($savepath)) {
-                session_save_path($savepath);
-            }
         }
     }