gRPC Status of Unknown

This repository consists of a test case that reveals the gRPC status of Unknown in the server stream.

If the underlying connection to the client is closed before sending the first message in a server stream, it gets a grpc error having the status of Unknown, as rpc error: code = Unknown desc = connection error: desc = "transport is closing". After an investigation, I found that if the connection is closed at the very beginning of the stream before the server writes the headers. When it writes the headers, it gets the ConnectionError and tries to convert it to a grpc status error by status.Convert(err).Err(). Since ConnectionError is not a grpc status error it converts the error to grpc status of Unknown.

Code snippet that runs this as follows:

// WriteHeader sends the header metadata md back to the client.
func (t *http2Server) WriteHeader(s *Stream, md metadata.MD) error {
	s.hdrMu.Lock()
	defer s.hdrMu.Unlock()
	if s.getState() == streamDone {
		return t.streamContextErr(s)
	}

	if s.updateHeaderSent() {
		return ErrIllegalHeaderWrite
	}

	if md.Len() > 0 {
		if s.header.Len() > 0 {
			s.header = metadata.Join(s.header, md)
		} else {
			s.header = md
		}
	}
	if err := t.writeHeaderLocked(s); err != nil {
		return status.Convert(err).Err()
	}
	return nil
}