Fix marshalling of raw_message field for empty messages (#106)

* Fix marshalling of raw_message field for empty messages

* Add changelog entry

* Fix null vs "" marshalling

CHANGELOG.md

@@ -1,5 +1,8 @@
 # Changelog
 
+## Unreleased
+* Fixed a bug that prevented replaying empty gRPC messages [#105](https:/bradleyjkemp/grpc-tools/pull/105).
+
 ## [v0.2.5](https:/bradleyjkemp/grpc-tools/releases/tag/v0.2.5)
 * Added grpc-proxy options `WithServerOptions` and `WithDialOptions`, deprecated `WithOptions` [#71](https:/bradleyjkemp/grpc-tools/pull/71).
 * Added a new command-line option, `--interface` to allow choosing which network interface `grpc-proxy` listens on [#81](https:/bradleyjkemp/grpc-tools/pull/81).

grpc-dump/dump/recorded_server_stream.go

@@ -42,6 +42,10 @@ func (ss *recordedServerStream) SetTrailer(trailers metadata.MD) {
 
 func (ss *recordedServerStream) SendMsg(m interface{}) error {
  message := m.([]byte)
+ if message == nil {
+ // although the message is nil here, we actually want to save it as the empty message ("")
+ message = []byte{}
+ }
  ss.Lock()
  ss.events = append(ss.events, &internal.Message{
  MessageOrigin: internal.ServerMessage,

internal/dump.go

@@ -35,7 +35,7 @@ const (
 
 type Message struct {
  MessageOrigin MessageOrigin `json:"message_origin,omitempty"`
- RawMessage []byte `json:"raw_message,omitempty"`
+ RawMessage []byte `json:"raw_message"`
  Message interface{} `json:"message,omitempty"`
  Timestamp time.Time `json:"timestamp"`
 }