Bug 1486445 - P1 - Propagate the sw internally redirected URL to fetching request; r=asuth

Bug 1222008 didn't propagate a sw redirected URL to outer response properly. To
fix that this patch mainly make a redirecting request be overwritten while it's
redirected by a service worker. This patch also add a private setter function
for InternalRequest and a public checking function to avoid that function from
being used widely.

Differential Revision: https://phabricator.services.mozilla.com/D4762

--HG--
extra : moz-landing-system : lando

dom/fetch/FetchDriver.cpp

@@ -1296,7 +1296,6 @@ FetchDriver::AsyncOnChannelRedirect(nsIChannel* aOldChannel,
   // However, ignore internal redirects here.  We don't want to flip
   // Response.redirected to true if an internal redirect occurs.  These
   // should be transparent to script.
-  if (!(aFlags & nsIChannelEventSink::REDIRECT_INTERNAL)) {
   nsCOMPtr<nsIURI> uri;
   MOZ_ALWAYS_SUCCEEDS(aNewChannel->GetURI(getter_AddRefs(uri)));
 
@@ -1316,7 +1315,12 @@ FetchDriver::AsyncOnChannelRedirect(nsIChannel* aOldChannel,
     return rv;
   }
 
+  if (!(aFlags & nsIChannelEventSink::REDIRECT_INTERNAL)) {
     mRequest->AddURL(spec, fragment);
+  } else {
+    // Overwrite the URL only when the request is redirected by a service
+    // worker.
+    mRequest->SetURLForInternalRedirect(aFlags, spec, fragment);
   }
 
   NS_ConvertUTF8toUTF16 tRPHeaderValue(tRPHeaderCValue);

dom/fetch/InternalRequest.h

@@ -133,6 +133,20 @@ public:
 
     return mURLList.LastElement();
   }
+
+  // A safe guard for ensuring that request's URL is only allowed to be set in a
+  // sw internal redirect.
+  void
+  SetURLForInternalRedirect(const uint32_t aFlag,
+                            const nsACString& aURL,
+                            const nsACString& aFragment)
+  {
+    // Only check in debug build to prevent it from being used unexpectedly.
+    MOZ_ASSERT(aFlag & nsIChannelEventSink::REDIRECT_INTERNAL);
+
+    return SetURL(aURL, aFragment);
+  }
+
   // AddURL should append the url into url list.
   // Normally we strip the fragment from the URL in Request::Constructor and
   // pass the fragment as the second argument into it.
@@ -578,6 +592,18 @@ private:
   static bool
   IsWorkerContentPolicy(nsContentPolicyType aContentPolicyType);
 
+  // It should only be called while there is a service-worker-internal-redirect.
+  void
+  SetURL(const nsACString& aURL, const nsACString& aFragment)
+  {
+    MOZ_ASSERT(!aURL.IsEmpty());
+    MOZ_ASSERT(!aURL.Contains('#'));
+    MOZ_ASSERT(mURLList.Length() > 0);
+
+    mURLList.LastElement() = aURL;
+    mFragment.Assign(aFragment);
+  }
+
   nsCString mMethod;
   // mURLList: a list of one or more fetch URLs
   nsTArray<nsCString> mURLList;