bug #36118 [Security/Http] don't require the session to be started wh…

…en tracking its id (nicolas-grekas)

This PR was merged into the 4.4 branch.

Discussion
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[Security/Http] don't require the session to be started when tracking its id

| Q             | A
| ------------- | ---
| Branch?       | 4.4
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Tickets       | -
| License       | MIT
| Doc PR        | -

`$session->getId()` returns the empty string when the session is not yet started.
When this happens, the session tracking logic wrongly detects that a new session was created and thus disables HTTP caching.

This fixes the issue by looking at the value of the session cookie instead.
(the case for `true` is when using `MockArraySessionStorage` as done in tests)

Commits
-------

c39188a [Security/Http] don't require the session to be started when tracking its id

src/Symfony/Component/Security/Http/Firewall/ContextListener.php

@@ -115,10 +115,10 @@ public function authenticate(RequestEvent $event)
 
         if (null !== $session) {
             $usageIndexValue = method_exists(Request::class, 'getPreferredFormat') && $session instanceof Session ? $usageIndexReference = &$session->getUsageIndex() : 0;
-            $sessionId = $session->getId();
+            $sessionId = $request->cookies->get($session->getName());
             $token = $session->get($this->sessionKey);
 
-            if ($this->sessionTrackerEnabler && $session->getId() === $sessionId) {
+            if ($this->sessionTrackerEnabler && \in_array($sessionId, [true, $session->getId()], true)) {
                 $usageIndexReference = $usageIndexValue;
             }
         }

src/Symfony/Component/Security/Http/Tests/Firewall/ContextListenerTest.php

@@ -344,6 +344,26 @@ public function testDeauthenticatedEvent()
         $this->assertNull($tokenStorage->getToken());
     }
 
+    /**
+     * @requires function \Symfony\Component\HttpFoundation\Request::getPreferredFormat
+     */
+    public function testWithPreviousNotStartedSession()
+    {
+        $session = new Session(new MockArraySessionStorage());
+
+        $request = new Request();
+        $request->setSession($session);
+        $request->cookies->set('MOCKSESSID', true);
+
+        $usageIndex = $session->getUsageIndex();
+
+        $tokenStorage = new TokenStorage();
+        $listener = new ContextListener($tokenStorage, [], 'context_key', null, null, null, [$tokenStorage, 'getToken']);
+        $listener(new RequestEvent($this->getMockBuilder(HttpKernelInterface::class)->getMock(), $request, HttpKernelInterface::MASTER_REQUEST));
+
+        $this->assertSame($usageIndex, $session->getUsageIndex());
+    }
+
     protected function runSessionOnKernelResponse($newToken, $original = null)
     {
         $session = new Session(new MockArraySessionStorage());