Fallback override

webkit/appcache/appcache_request_handler.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "webkit/appcache/appcache_request_handler.h"
 
 #include "net/url_request/url_request.h"
 #include "net/url_request/url_request_job.h"
 #include "webkit/appcache/appcache.h"
 #include "webkit/appcache/appcache_url_request_job.h"
@@ skipping 119 matching lines @@
   // We don't fallback for responses that we delivered.
   if (job_) {
     DCHECK(!job_->is_delivering_network_response());
     return NULL;
   }
 
   if (request->status().is_success()) {
     int code_major = request->GetResponseCode() / 100;
     if (code_major !=4 && code_major != 5)
       return NULL;
+
+    // Servers can override the fallback behavior with a response header.
+    const std::string kFallbackOverrideHeader(
+        "x-chromium-appcache-fallback-override");
+    const std::string kFallbackOverrideValue(
+        "disallow-fallback");
+    std::string header_value;
+    request->GetResponseHeaderByName(kFallbackOverrideHeader, &header_value);
+    if (header_value == kFallbackOverrideValue)
+      return NULL;
   }
 
   // 6.9.6, step 4: If this results in a 4xx or 5xx status code
   // or there were network errors, get the resource of the fallback entry.
   job_ = new AppCacheURLRequestJob(request, storage());
   DeliverAppCachedResponse(
       found_fallback_entry_, found_cache_id_,  found_manifest_url_,
       true, found_fallback_url_);
   return job_;
 }
@@ skipping 184 matching lines @@
   if (!host_->associated_cache() ||
       !host_->associated_cache()->is_complete()) {
     DeliverNetworkResponse();
     return;
   }
 
   ContinueMaybeLoadSubResource();
 }
 
 }  // namespace appcache