HTTP backend: do not load resources from cache that must be revalidated

The header field "Cache-Control: must-revalidate" is a strict
requirement for loading the resource from the server, and not reading it
from the cache without revalidating first. With this patch, PreferCache
will load such from the network instead of loading them from the cache,
and AlwaysCache will throw a ContentNotFound error.

Reviewed-by: Markus Goetz
Task-number: QTBUG-18983
(cherry picked from commit 0e449f38894b1bd2dbb2f14206a011424679f063)

1 files changed, 5 insertions, 7 deletions

diff --git a/src/network/access/qnetworkaccesshttpbackend.cpp b/src/network/access/qnetworkaccesshttpbackend.cpp
index c61911445b..a45c2de0b2 100644
--- a/src/network/access/qnetworkaccesshttpbackend.cpp
+++ b/src/network/access/qnetworkaccesshttpbackend.cpp
@@ -262,13 +262,11 @@ bool QNetworkAccessHttpBackend::loadFromCacheIfAllowed(QHttpNetworkRequest &http
     if (lastModified.isValid())
         httpRequest.setHeaderField("If-Modified-Since", QNetworkHeadersPrivate::toHttpDate(lastModified));
 
-    if (CacheLoadControlAttribute == QNetworkRequest::PreferNetwork) {
-        it = cacheHeaders.findRawHeader("Cache-Control");
-        if (it != cacheHeaders.rawHeaders.constEnd()) {
-            QHash<QByteArray, QByteArray> cacheControl = parseHttpOptionHeader(it->second);
-            if (cacheControl.contains("must-revalidate"))
-                return false;
-        }
+    it = cacheHeaders.findRawHeader("Cache-Control");
+    if (it != cacheHeaders.rawHeaders.constEnd()) {
+        QHash<QByteArray, QByteArray> cacheControl = parseHttpOptionHeader(it->second);
+        if (cacheControl.contains("must-revalidate"))
+            return false;
     }
 
     QDateTime currentDateTime = QDateTime::currentDateTime();