[bugfix] Do not cache invalid WM(T)S responses

The problem here was that in case of http->https redirect from a misconfigured server (that advertizes http and then redirects all request to https) all http redirect requests were cached, making all subsequent requests to the same url hit the 301 Moved Permanently reponse page intead of the redirected content. Fixes #16427 WMTS rendering problems in 2.18 and Master cherry-picked from d102404
qgis · Oct 4, 2017 · b09fb37 · b09fb37
1 parent f14502e
commit b09fb37
Showing 1 changed file with 10 additions and 6 deletions.
diff --git a/src/providers/wms/qgstilecache.cpp b/src/providers/wms/qgstilecache.cpp
@@ -33,10 +33,11 @@ void QgsTileCache::insertTile( const QUrl& url, const QImage& image )
 bool QgsTileCache::tile( const QUrl& url, QImage& image )
 {
   QMutexLocker locker( &sTileCacheMutex );
-  if ( QImage* i = sTileCache.object( url ) )
+  bool success = false;
+  if ( QImage *i = sTileCache.object( url ) )
   {
     image = *i;
-    return true;
+    success = true;
   }
   else if ( QgsNetworkAccessManager::instance()->cache()->metaData( url ).isValid() )
   {
@@ -48,10 +49,13 @@ bool QgsTileCache::tile( const QUrl& url, QImage& image )
       image = QImage::fromData( imageData );
 
       // cache it as well (mutex is already locked)
-      sTileCache.insert( url, new QImage( image ) );
-
-      return true;
+      // Check for null because it could be a redirect (see: https://issues.qgis.org/issues/16427 )
+      if ( ! image.isNull( ) )
+      {
+        sTileCache.insert( url, new QImage( image ) );
+        success = true;
+      }
     }
   }
-  return false;
+  return success;
 }