1 files changed, 85 insertions, 0 deletions
diff --git a/dom/html/MediaError.cpp b/dom/html/MediaError.cpp
new file mode 100644
index 0000000000..beb37f7232
--- /dev/null
+++ b/dom/html/MediaError.cpp
@@ -0,0 +1,85 @@
+/* -*- 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 "mozilla/dom/MediaError.h"
+
+#include <string>
+#include <unordered_set>
+
+#include "mozilla/dom/Document.h"
+#include "mozilla/dom/MediaErrorBinding.h"
+#include "nsContentUtils.h"
+#include "nsIScriptError.h"
+#include "jsapi.h"
+#include "js/Warnings.h"  // JS::WarnASCII
+
+namespace mozilla::dom {
+
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(MediaError, mParent)
+NS_IMPL_CYCLE_COLLECTING_ADDREF(MediaError)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(MediaError)
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(MediaError)
+  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+MediaError::MediaError(HTMLMediaElement* aParent, uint16_t aCode,
+                       const nsACString& aMessage)
+    : mParent(aParent), mCode(aCode), mMessage(aMessage) {}
+
+void MediaError::GetMessage(nsAString& aResult) const {
+  // When fingerprinting resistance is enabled, only messages in this list
+  // can be returned to content script.
+  // FIXME: An unordered_set seems overkill for this.
+  static const std::unordered_set<std::string> whitelist = {
+      "404: Not Found"
+      // TODO
+  };
+
+  const bool shouldBlank = whitelist.find(mMessage.get()) == whitelist.end();
+
+  if (shouldBlank) {
+    // Print a warning message to JavaScript console to alert developers of
+    // a non-whitelisted error message.
+    nsAutoCString message =
+        nsLiteralCString(
+            "This error message will be blank when "
+            "privacy.resistFingerprinting = true."
+            "  If it is really necessary, please add it to the whitelist in"
+            " MediaError::GetMessage: ") +
+        mMessage;
+    Document* ownerDoc = mParent->OwnerDoc();
+    AutoJSAPI api;
+    if (api.Init(ownerDoc->GetScopeObject())) {
+      // We prefer this API because it can also print to our debug log and
+      // try server's log viewer.
+      JS::WarnASCII(api.cx(), "%s", message.get());
+    } else {
+      // If failed to use JS::WarnASCII, fall back to
+      // nsContentUtils::ReportToConsoleNonLocalized, which can only print to
+      // JavaScript console.
+      nsContentUtils::ReportToConsoleNonLocalized(
+          NS_ConvertASCIItoUTF16(message), nsIScriptError::warningFlag,
+          "MediaError"_ns, ownerDoc);
+    }
+
+    if (!nsContentUtils::IsCallerChrome() &&
+        ownerDoc->ShouldResistFingerprinting()) {
+      aResult.Truncate();
+      return;
+    }
+  }
+
+  CopyUTF8toUTF16(mMessage, aResult);
+}
+
+JSObject* MediaError::WrapObject(JSContext* aCx,
+                                 JS::Handle<JSObject*> aGivenProto) {
+  return MediaError_Binding::Wrap(aCx, this, aGivenProto);
+}
+
+}  // namespace mozilla::dom