Bug 1500879 - Fetch should not consume Request/Response with null-body, r=asuth

The fetch spec treats null bodies specially.  Their Body cannot become
disturbed or locked and a fresh empty ReadableStream is returned whenever an
attempt is made to consume the body.  We currently fail a number of WPT tests
in this area because we do mark the body consumed as exposed via bodyUsed.

dom/fetch/EmptyBody.cpp

@@ -0,0 +1,82 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "EmptyBody.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(EmptyBody)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(EmptyBody)
+
+NS_IMPL_CYCLE_COLLECTION_CLASS(EmptyBody)
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(EmptyBody)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mOwner)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mAbortSignalImpl)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mFetchStreamReader)
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(EmptyBody)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mOwner)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mAbortSignalImpl)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mFetchStreamReader)
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN(EmptyBody)
+NS_IMPL_CYCLE_COLLECTION_TRACE_END
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(EmptyBody)
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+EmptyBody::EmptyBody(nsIGlobalObject* aGlobal,
+                     mozilla::ipc::PrincipalInfo* aPrincipalInfo,
+                     AbortSignalImpl* aAbortSignalImpl,
+                     already_AddRefed<nsIInputStream> aBodyStream)
+  : FetchBody<EmptyBody>(aGlobal)
+  , mPrincipalInfo(aPrincipalInfo)
+  , mAbortSignalImpl(aAbortSignalImpl)
+  , mBodyStream(std::move(aBodyStream))
+{}
+
+EmptyBody::~EmptyBody() = default;
+
+/* static */ already_AddRefed<EmptyBody>
+EmptyBody::Create(nsIGlobalObject* aGlobal,
+                  mozilla::ipc::PrincipalInfo* aPrincipalInfo,
+                  AbortSignalImpl* aAbortSignalImpl,
+                  const nsACString& aMimeType,
+                  ErrorResult& aRv)
+{
+  nsCOMPtr<nsIInputStream> bodyStream;
+  aRv = NS_NewCStringInputStream(getter_AddRefs(bodyStream), EmptyCString());
+  if (NS_WARN_IF(aRv.Failed())) {
+    return nullptr;
+  }
+
+  RefPtr<EmptyBody> emptyBody = new EmptyBody(aGlobal, aPrincipalInfo,
+                                              aAbortSignalImpl,
+                                              bodyStream.forget());
+  emptyBody->OverrideMimeType(aMimeType);
+  return emptyBody.forget();
+}
+
+void
+EmptyBody::GetBody(nsIInputStream** aStream, int64_t* aBodyLength)
+{
+  MOZ_ASSERT(aStream);
+
+  if (aBodyLength) {
+    *aBodyLength = 0;
+  }
+
+  nsCOMPtr<nsIInputStream> bodyStream = mBodyStream;
+  bodyStream.forget(aStream);
+}
+
+} // dom namespace
+} // mozilla namespace

dom/fetch/EmptyBody.h

@@ -0,0 +1,89 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_EmptyBody_h
+#define mozilla_dom_EmptyBody_h
+
+#include "nsISupportsImpl.h"
+
+#include "mozilla/dom/Fetch.h"
+
+namespace mozilla {
+
+namespace ipc {
+class PrincipalInfo;
+} // namespace ipc
+
+namespace dom {
+
+class EmptyBody final : public nsISupports
+                      , public FetchBody<EmptyBody>
+{
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(EmptyBody)
+
+public:
+  static already_AddRefed<EmptyBody>
+  Create(nsIGlobalObject* aGlobal,
+         mozilla::ipc::PrincipalInfo* aPrincipalInfo,
+         AbortSignalImpl* aAbortSignalImpl,
+         const nsACString& aMimeType,
+         ErrorResult& aRv);
+
+  nsIGlobalObject*
+  GetParentObject() const
+  {
+    return mOwner;
+  }
+
+  AbortSignalImpl*
+  GetSignalImpl() const override
+  {
+    return mAbortSignalImpl;
+  }
+
+  const UniquePtr<mozilla::ipc::PrincipalInfo>&
+  GetPrincipalInfo() const
+  {
+    return mPrincipalInfo;
+  }
+
+  void
+  GetBody(nsIInputStream** aStream, int64_t* aBodyLength = nullptr);
+
+  using FetchBody::BodyBlobURISpec;
+
+  const nsACString&
+  BodyBlobURISpec() const
+  {
+    return EmptyCString();
+  }
+
+  using FetchBody::BodyLocalPath;
+
+  const nsAString&
+  BodyLocalPath() const
+  {
+    return EmptyString();
+  }
+
+private:
+  EmptyBody(nsIGlobalObject* aGlobal,
+            mozilla::ipc::PrincipalInfo* aPrincipalInfo,
+            AbortSignalImpl* aAbortSignalImpl,
+            already_AddRefed<nsIInputStream> mBodyStream);
+
+  ~EmptyBody();
+
+  UniquePtr<mozilla::ipc::PrincipalInfo> mPrincipalInfo;
+  RefPtr<AbortSignalImpl> mAbortSignalImpl;
+  nsCOMPtr<nsIInputStream> mBodyStream;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_EmptyBody_h

dom/fetch/Fetch.cpp

@@ -40,6 +40,7 @@
 #include "mozilla/Telemetry.h"
 
 #include "BodyExtractor.h"
+#include "EmptyBody.h"
 #include "FetchObserver.h"
 #include "InternalRequest.h"
 #include "InternalResponse.h"
@@ -1242,6 +1243,29 @@ FetchBody<Derived>::ConsumeBody(JSContext* aCx, FetchConsumeType aType,
     return nullptr;
   }
 
+  // Null bodies are a special-case in the fetch spec.  The Body mix-in can only
+  // be "disturbed" or "locked" if its associated "body" is non-null.
+  // Additionally, the Body min-in's "consume body" algorithm explicitly creates
+  // a fresh empty ReadableStream object in step 2.  This means that `bodyUsed`
+  // will never return true for a null body.
+  //
+  // To this end, we create a fresh (empty) body every time a request is made
+  // and consume its body here, without marking this FetchBody consumed via
+  // SetBodyUsed.
+  nsCOMPtr<nsIInputStream> bodyStream;
+  DerivedClass()->GetBody(getter_AddRefs(bodyStream));
+  if (!bodyStream) {
+    RefPtr<EmptyBody> emptyBody =
+      EmptyBody::Create(DerivedClass()->GetParentObject(),
+                        DerivedClass()->GetPrincipalInfo().get(),
+                        signalImpl, mMimeType, aRv);
+    if (NS_WARN_IF(aRv.Failed())) {
+      return nullptr;
+    }
+
+    return emptyBody->ConsumeBody(aCx, aType, aRv);
+  }
+
   SetBodyUsed(aCx, aRv);
   if (NS_WARN_IF(aRv.Failed())) {
     return nullptr;
@@ -1251,7 +1275,7 @@ FetchBody<Derived>::ConsumeBody(JSContext* aCx, FetchConsumeType aType,
 
   RefPtr<Promise> promise =
     FetchBodyConsumer<Derived>::Create(global, mMainThreadEventTarget, this,
-                                       signalImpl, aType, aRv);
+                                       bodyStream, signalImpl, aType, aRv);
   if (NS_WARN_IF(aRv.Failed())) {
     return nullptr;
   }
@@ -1269,6 +1293,11 @@ already_AddRefed<Promise>
 FetchBody<Response>::ConsumeBody(JSContext* aCx, FetchConsumeType aType,
                                  ErrorResult& aRv);
 
+template
+already_AddRefed<Promise>
+FetchBody<EmptyBody>::ConsumeBody(JSContext* aCx, FetchConsumeType aType,
+                                  ErrorResult& aRv);
+
 template <class Derived>
 void
 FetchBody<Derived>::SetMimeType()
@@ -1297,6 +1326,13 @@ template
 void
 FetchBody<Response>::SetMimeType();
 
+template <class Derived>
+void
+FetchBody<Derived>::OverrideMimeType(const nsACString& aMimeType)
+{
+  mMimeType = aMimeType;
+}
+
 template <class Derived>
 const nsACString&
 FetchBody<Derived>::BodyBlobURISpec() const
@@ -1312,6 +1348,10 @@ template
 const nsACString&
 FetchBody<Response>::BodyBlobURISpec() const;
 
+template
+const nsACString&
+FetchBody<EmptyBody>::BodyBlobURISpec() const;
+
 template <class Derived>
 const nsAString&
 FetchBody<Derived>::BodyLocalPath() const
@@ -1327,6 +1367,10 @@ template
 const nsAString&
 FetchBody<Response>::BodyLocalPath() const;
 
+template
+const nsAString&
+FetchBody<EmptyBody>::BodyLocalPath() const;
+
 template <class Derived>
 void
 FetchBody<Derived>::SetReadableStreamBody(JSContext* aCx, JSObject* aBody)

dom/fetch/Fetch.h

@@ -267,6 +267,9 @@ public:
   void
   Abort() override;
 
+  already_AddRefed<Promise>
+  ConsumeBody(JSContext* aCx, FetchConsumeType aType, ErrorResult& aRv);
+
 protected:
   nsCOMPtr<nsIGlobalObject> mOwner;
 
@@ -288,6 +291,9 @@ protected:
   void
   SetMimeType();
 
+  void
+  OverrideMimeType(const nsACString& aMimeType);
+
   void
   SetReadableStreamBody(JSContext* aCx, JSObject* aBody);
 
@@ -298,9 +304,6 @@ private:
     return static_cast<Derived*>(const_cast<FetchBody*>(this));
   }
 
-  already_AddRefed<Promise>
-  ConsumeBody(JSContext* aCx, FetchConsumeType aType, ErrorResult& aRv);
-
   void
   LockStream(JSContext* aCx, JS::HandleObject aStream, ErrorResult& aRv);
 

dom/fetch/FetchConsumer.cpp

@@ -323,22 +323,15 @@ template <class Derived>
 FetchBodyConsumer<Derived>::Create(nsIGlobalObject* aGlobal,
                                    nsIEventTarget* aMainThreadEventTarget,
                                    FetchBody<Derived>* aBody,
+                                   nsIInputStream* aBodyStream,
                                    AbortSignalImpl* aSignalImpl,
                                    FetchConsumeType aType,
                                    ErrorResult& aRv)
 {
   MOZ_ASSERT(aBody);
+  MOZ_ASSERT(aBodyStream);
   MOZ_ASSERT(aMainThreadEventTarget);
 
-  nsCOMPtr<nsIInputStream> bodyStream;
-  aBody->DerivedClass()->GetBody(getter_AddRefs(bodyStream));
-  if (!bodyStream) {
-    aRv = NS_NewCStringInputStream(getter_AddRefs(bodyStream), EmptyCString());
-    if (NS_WARN_IF(aRv.Failed())) {
-      return nullptr;
-    }
-  }
-
   RefPtr<Promise> promise = Promise::Create(aGlobal, aRv);
   if (aRv.Failed()) {
     return nullptr;
@@ -346,7 +339,7 @@ FetchBodyConsumer<Derived>::Create(nsIGlobalObject* aGlobal,
 
   RefPtr<FetchBodyConsumer<Derived>> consumer =
     new FetchBodyConsumer<Derived>(aMainThreadEventTarget, aGlobal,
-                                   aBody, bodyStream, promise,
+                                   aBody, aBodyStream, promise,
                                    aType);
 
   RefPtr<ThreadSafeWorkerRef> workerRef;

dom/fetch/FetchConsumer.h

@@ -39,6 +39,7 @@ public:
   Create(nsIGlobalObject* aGlobal,
          nsIEventTarget* aMainThreadEventTarget,
          FetchBody<Derived>* aBody,
+         nsIInputStream* aBodyStream,
          AbortSignalImpl* aSignalImpl,
          FetchConsumeType aType,
          ErrorResult& aRv);

dom/fetch/moz.build

@@ -27,6 +27,7 @@ EXPORTS.mozilla.dom += [
 UNIFIED_SOURCES += [
     'BodyExtractor.cpp',
     'ChannelInfo.cpp',
+    'EmptyBody.cpp',
     'Fetch.cpp',
     'FetchConsumer.cpp',
     'FetchDriver.cpp',

testing/web-platform/meta/fetch/api/request/request-consume-empty.html.ini

@@ -1,32 +1,4 @@
 [request-consume-empty.html]
-  max-asserts: 2
-  [Consume request's body as text]
-    expected: FAIL
-
-  [Consume request's body as blob]
-    expected: FAIL
-
-  [Consume request's body as arrayBuffer]
-    expected: FAIL
-
-  [Consume request's body as json]
-    expected: FAIL
-
-  [Consume request's body as formData]
-    expected: FAIL
-
   [Consume empty FormData request body as text]
     expected: FAIL
 
-  [Consume request's body as json (error case)]
-    expected: FAIL
-
-  [Consume request's body as formData with correct multipart type (error case)]
-    expected: FAIL
-
-  [Consume request's body as formData with correct urlencoded type]
-    expected: FAIL
-
-  [Consume request's body as formData without correct type (error case)]
-    expected: FAIL
-

testing/web-platform/meta/fetch/api/request/request-disturbed.html.ini

@@ -1,7 +1,4 @@
 [request-disturbed.html]
-  [Request without body cannot be disturbed]
-    expected: FAIL
-
   [Request's body: initial state]
     expected: FAIL
 

testing/web-platform/meta/fetch/api/response/response-consume-empty.html.ini

@@ -1,32 +1,3 @@
 [response-consume-empty.html]
-  max-asserts: 2
-  [Consume response's body as text]
-    expected: FAIL
-
-  [Consume response's body as blob]
-    expected: FAIL
-
-  [Consume response's body as arrayBuffer]
-    expected: FAIL
-
-  [Consume response's body as json]
-    expected: FAIL
-
-  [Consume response's body as formData]
-    expected: FAIL
-
   [Consume empty FormData response body as text]
     expected: FAIL
-
-  [Consume response's body as json (error case)]
-    expected: FAIL
-
-  [Consume response's body as formData with correct multipart type (error case)]
-    expected: FAIL
-
-  [Consume response's body as formData with correct urlencoded type]
-    expected: FAIL
-
-  [Consume response's body as formData without correct type (error case)]
-    expected: FAIL
-

testing/web-platform/meta/service-workers/cache-storage/serviceworker/cache-add.https.html.ini

@@ -1,4 +0,0 @@
-[cache-add.https.html]
-  [Cache.add with request with null body (not consumed)]
-    expected: FAIL
-

testing/web-platform/meta/service-workers/cache-storage/window/cache-add.https.html.ini

@@ -1,4 +0,0 @@
-[cache-add.https.html]
-  [Cache.add with request with null body (not consumed)]
-    expected: FAIL
-

testing/web-platform/meta/service-workers/cache-storage/worker/cache-add.https.html.ini

@@ -1,4 +0,0 @@
-[cache-add.https.html]
-  [Cache.add with request with null body (not consumed)]
-    expected: FAIL
-