1 files changed, 154 insertions, 0 deletions
diff --git a/dom/base/SerializedStackHolder.cpp b/dom/base/SerializedStackHolder.cpp
new file mode 100644
index 0000000000..199879e226
--- /dev/null
+++ b/dom/base/SerializedStackHolder.cpp
@@ -0,0 +1,154 @@
+/* -*- 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 "SerializedStackHolder.h"
+
+#include "js/SavedFrameAPI.h"
+#include "mozilla/dom/WorkerPrivate.h"
+#include "mozilla/dom/ScriptSettings.h"
+#include "mozilla/Services.h"
+#include "nsJSPrincipals.h"
+#include "nsIObserverService.h"
+#include "xpcpublic.h"
+
+namespace mozilla::dom {
+
+SerializedStackHolder::SerializedStackHolder()
+    : mHolder(StructuredCloneHolder::CloningSupported,
+              StructuredCloneHolder::TransferringNotSupported,
+              StructuredCloneHolder::StructuredCloneScope::SameProcess) {}
+
+void SerializedStackHolder::WriteStack(JSContext* aCx,
+                                       JS::Handle<JSObject*> aStack) {
+  JS::Rooted<JS::Value> stackValue(aCx, JS::ObjectValue(*aStack));
+  mHolder.Write(aCx, stackValue, IgnoreErrors());
+
+  // StructuredCloneHolder::Write can leave a pending exception on the context.
+  JS_ClearPendingException(aCx);
+}
+
+void SerializedStackHolder::SerializeMainThreadOrWorkletStack(
+    JSContext* aCx, JS::Handle<JSObject*> aStack) {
+  MOZ_ASSERT(!IsCurrentThreadRunningWorker());
+  WriteStack(aCx, aStack);
+}
+
+void SerializedStackHolder::SerializeWorkerStack(JSContext* aCx,
+                                                 WorkerPrivate* aWorkerPrivate,
+                                                 JS::Handle<JSObject*> aStack) {
+  MOZ_ASSERT(aWorkerPrivate->IsOnCurrentThread());
+
+  RefPtr<StrongWorkerRef> workerRef =
+      StrongWorkerRef::Create(aWorkerPrivate, "WorkerErrorReport");
+  if (workerRef) {
+    mWorkerRef = new ThreadSafeWorkerRef(workerRef);
+  } else {
+    // Don't write the stack if we can't create a ref to the worker.
+    return;
+  }
+
+  WriteStack(aCx, aStack);
+}
+
+void SerializedStackHolder::SerializeCurrentStack(JSContext* aCx) {
+  JS::Rooted<JSObject*> stack(aCx);
+  if (JS::CurrentGlobalOrNull(aCx) && !JS::CaptureCurrentStack(aCx, &stack)) {
+    JS_ClearPendingException(aCx);
+    return;
+  }
+
+  if (stack) {
+    if (NS_IsMainThread()) {
+      SerializeMainThreadOrWorkletStack(aCx, stack);
+    } else {
+      WorkerPrivate* currentWorker = GetCurrentThreadWorkerPrivate();
+      SerializeWorkerStack(aCx, currentWorker, stack);
+    }
+  }
+}
+
+JSObject* SerializedStackHolder::ReadStack(JSContext* aCx) {
+  MOZ_ASSERT(NS_IsMainThread());
+  if (!mHolder.HasData()) {
+    return nullptr;
+  }
+
+  JS::Rooted<JS::Value> stackValue(aCx);
+
+  mHolder.Read(xpc::CurrentNativeGlobal(aCx), aCx, &stackValue, IgnoreErrors());
+
+  return stackValue.isObject() ? &stackValue.toObject() : nullptr;
+}
+
+UniquePtr<SerializedStackHolder> GetCurrentStackForNetMonitor(JSContext* aCx) {
+  MOZ_ASSERT_IF(!NS_IsMainThread(),
+                GetCurrentThreadWorkerPrivate()->IsWatchedByDevTools());
+
+  return GetCurrentStack(aCx);
+}
+
+UniquePtr<SerializedStackHolder> GetCurrentStack(JSContext* aCx) {
+  UniquePtr<SerializedStackHolder> stack = MakeUnique<SerializedStackHolder>();
+  stack->SerializeCurrentStack(aCx);
+  return stack;
+}
+
+void NotifyNetworkMonitorAlternateStack(
+    nsISupports* aChannel, UniquePtr<SerializedStackHolder> aStackHolder) {
+  if (!aStackHolder) {
+    return;
+  }
+
+  nsString stackString;
+  ConvertSerializedStackToJSON(std::move(aStackHolder), stackString);
+
+  if (!stackString.IsEmpty()) {
+    NotifyNetworkMonitorAlternateStack(aChannel, stackString);
+  }
+}
+
+void ConvertSerializedStackToJSON(UniquePtr<SerializedStackHolder> aStackHolder,
+                                  nsAString& aStackString) {
+  // We need a JSContext to be able to stringify the SavedFrame stack.
+  // This will not run any scripts. A privileged scope is needed to fully
+  // inspect all stack frames we find.
+  AutoJSAPI jsapi;
+  DebugOnly<bool> ok = jsapi.Init(xpc::PrivilegedJunkScope());
+  JSContext* cx = jsapi.cx();
+
+  JS::Rooted<JSObject*> savedFrame(cx, aStackHolder->ReadStack(cx));
+  if (!savedFrame) {
+    return;
+  }
+
+  JS::Rooted<JSObject*> converted(cx);
+  converted = JS::ConvertSavedFrameToPlainObject(
+      cx, savedFrame, JS::SavedFrameSelfHosted::Exclude);
+  if (!converted) {
+    JS_ClearPendingException(cx);
+    return;
+  }
+
+  JS::Rooted<JS::Value> convertedValue(cx, JS::ObjectValue(*converted));
+  if (!nsContentUtils::StringifyJSON(cx, convertedValue, aStackString,
+                                     UndefinedIsNullStringLiteral)) {
+    JS_ClearPendingException(cx);
+    return;
+  }
+}
+
+void NotifyNetworkMonitorAlternateStack(nsISupports* aChannel,
+                                        const nsAString& aStackJSON) {
+  nsCOMPtr<nsIObserverService> obsService = services::GetObserverService();
+  if (!obsService) {
+    return;
+  }
+
+  obsService->NotifyObservers(aChannel, "network-monitor-alternate-stack",
+                              PromiseFlatString(aStackJSON).get());
+}
+
+}  // namespace mozilla::dom