Issue #3350593: Use s-maxage instead of max-age

src/EventSubscriber/CacheControlOverrideSubscriber.php

@@ -65,25 +65,26 @@ final class CacheControlOverrideSubscriber implements EventSubscriberInterface {
 
     $maxAge = (int) $response->getCacheableMetadata()->getCacheMaxAge();
 
-    // We treat permanent cache max-age as default therefore we don't override
-    // the max-age.
-    if ($maxAge !== CacheBackendInterface::CACHE_PERMANENT) {
-      // If max-age is not uncacheable (0), check if max-age should be changed.
-      if ($maxAge > 0) {
-        // Force minimum max-age if configured.
-        $minimum = $this->getMaxAgeMinimum();
-        if ($minimum !== NULL) {
-          $maxAge = max($minimum, $maxAge);
-        }
-
-        // Force maximum max-age if configured.
-        $maximum = $this->getMaxAgeMaximum();
-        if ($maximum !== NULL && $maximum !== CacheBackendInterface::CACHE_PERMANENT) {
-          $maxAge = min($maximum, $maxAge);
-        }
+    if ($maxAge == CacheBackendInterface::CACHE_PERMANENT) {
+      // Permanent is -1 so we must replace it with the value from core configuration.
+      $maxAge = $this->configFactory->get('system.performance')->get('cache.page.max_age');
+    }
+
+    // If max-age is not uncacheable (0), check if max-age should be changed.
+    if ($maxAge > 0) {
+      // Force minimum max-age if configured.
+      $minimum = $this->getMaxAgeMinimum();
+      if ($minimum !== NULL) {
+        $maxAge = max($minimum, $maxAge);
+      }
+
+      // Force maximum max-age if configured.
+      $maximum = $this->getMaxAgeMaximum();
+      if ($maximum !== NULL && $maximum !== CacheBackendInterface::CACHE_PERMANENT) {
+        $maxAge = min($maximum, $maxAge);
       }
-      $response->headers->set('Cache-Control', 'public, max-age=' . $maxAge);
     }
+    $response->headers->set('Cache-Control', 'public, max-age=0, must-revalidate, s-maxage=' . $maxAge);
   }
 
   /**