Bug 1615481. Throw the right exception from DataChannel.send() when the message is too big. r=jib

Differential Revision: https://phabricator.services.mozilla.com/D62850

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

netwerk/sctp/datachannel/DataChannel.cpp

@@ -3081,13 +3081,17 @@ void DataChannel::SetListener(DataChannelListener* aListener,
   mListener = aListener;
 }
 
-void DataChannel::SendErrnoToErrorResult(int error, ErrorResult& aRv) {
+void DataChannel::SendErrnoToErrorResult(int error, size_t aMessageSize,
+                                         ErrorResult& aRv) {
   switch (error) {
     case 0:
       break;
-    case EMSGSIZE:
-      aRv.Throw(NS_ERROR_DOM_TYPE_ERR);
+    case EMSGSIZE: {
+      nsPrintfCString err("Message size (%zu) exceeds maxMessageSize",
+                          aMessageSize);
+      aRv.ThrowTypeError(NS_ConvertUTF8toUTF16(err));
       break;
+    }
     default:
       aRv.Throw(NS_ERROR_DOM_OPERATION_ERR);
       break;
@@ -3173,7 +3177,8 @@ void DataChannel::SendMsg(const nsACString& aMsg, ErrorResult& aRv) {
     return;
   }
 
-  SendErrnoToErrorResult(mConnection->SendMsg(mStream, aMsg), aRv);
+  SendErrnoToErrorResult(mConnection->SendMsg(mStream, aMsg), aMsg.Length(),
+                         aRv);
   if (!aRv.Failed()) {
     IncrementBufferedAmount(aMsg.Length(), aRv);
   }
@@ -3184,7 +3189,8 @@ void DataChannel::SendBinaryMsg(const nsACString& aMsg, ErrorResult& aRv) {
     return;
   }
 
-  SendErrnoToErrorResult(mConnection->SendBinaryMsg(mStream, aMsg), aRv);
+  SendErrnoToErrorResult(mConnection->SendBinaryMsg(mStream, aMsg),
+                         aMsg.Length(), aRv);
   if (!aRv.Failed()) {
     IncrementBufferedAmount(aMsg.Length(), aRv);
   }
@@ -3214,7 +3220,8 @@ void DataChannel::SendBinaryBlob(dom::Blob& aBlob, ErrorResult& aRv) {
     return;
   }
 
-  SendErrnoToErrorResult(mConnection->SendBlob(mStream, msgStream), aRv);
+  SendErrnoToErrorResult(mConnection->SendBlob(mStream, msgStream), msgLength,
+                         aRv);
   if (!aRv.Failed()) {
     IncrementBufferedAmount(msgLength, aRv);
   }

netwerk/sctp/datachannel/DataChannel.h

@@ -449,7 +449,8 @@ class DataChannel {
   void SetListener(DataChannelListener* aListener, nsISupports* aContext);
 
   // Helper for send methods that converts POSIX error codes to an ErrorResult.
-  static void SendErrnoToErrorResult(int error, ErrorResult& aRv);
+  static void SendErrnoToErrorResult(int error, size_t aMessageSize,
+                                     ErrorResult& aRv);
 
   // Send a string
   void SendMsg(const nsACString& aMsg, ErrorResult& aRv);

testing/web-platform/tests/webrtc/RTCDataChannel-send.html

@@ -313,6 +313,6 @@ promise_test(async t => {
   // "send" method step 4:
   // If the byte size of "data" exceeds the value of maxMessageSize, throw
   // a TypeError.
-  assert_throws_dom('TypeError', () => channel1.send(message));
+  assert_throws_js(TypeError, () => channel1.send(message));
 }, 'Calling send() up to max size should succeed, above max size should fail');
 </script>