Use jsonpb to (un)marshall messages to/from JSON

The stdlib encoding/json package isn't able to (un)marshal some advanced protobuf features such as `oneof` fields, so jsonpb should be used instead

cmd/_integration-tests/transport/http_test.go

@@ -17,6 +17,7 @@ import (
 	pb "github.com/Unity-Technologies/truss/cmd/_integration-tests/transport/proto"
 	httpclient "github.com/Unity-Technologies/truss/cmd/_integration-tests/transport/transportpermutations-service/svc/client/http"
 
+	"github.com/golang/protobuf/jsonpb"
 	"github.com/pkg/errors"
 )
 
@@ -643,7 +644,21 @@ func testHTTP(
 		t.Fatal(errors.Wrap(err, "cannot make http request"))
 	}
 
-	err = json.Unmarshal(respBytes, &resp)
+	switch v := resp.(type) {
+	case *pb.GetWithQueryResponse:
+		err = jsonpb.UnmarshalString(string(respBytes), v)
+	case *pb.GetWithRepeatedQueryResponse:
+		err = jsonpb.UnmarshalString(string(respBytes), v)
+	case *pb.GetWithEnumQueryResponse:
+		err = jsonpb.UnmarshalString(string(respBytes), v)
+	case *pb.PostWithNestedMessageBodyResponse:
+		err = jsonpb.UnmarshalString(string(respBytes), v)
+	case *pb.MetaResponse:
+		err = jsonpb.UnmarshalString(string(respBytes), v)
+	default:
+		t.Fatalf("Unknown response type: %T", v)
+	}
+
 	if err != nil {
 		t.Fatal(errors.Wrapf(err, "json error, got response: %q", string(respBytes)))
 	}

gengokit/httptransport/templates/client.go

@@ -92,6 +92,10 @@ import (
 	"strings"
 	"context"
 
+	{{ if len .HTTPHelper.Methods -}}
+		"github.com/golang/protobuf/jsonpb"
+	{{- end }}
+
 	"github.com/go-kit/kit/endpoint"
 	httptransport "github.com/go-kit/kit/transport/http"
 	"github.com/pkg/errors"
@@ -227,7 +231,7 @@ func contextValuesToHttpHeaders(keys []string) httptransport.RequestFunc {
 		}
 
 		var resp pb.{{GoName $method.ResponseType}}
-		if err = json.Unmarshal(buf, &resp); err != nil {
+		if err = jsonpb.UnmarshalString(string(buf), &resp); err != nil {
 			return nil, errorDecoder(buf)
 		}
 

gengokit/httptransport/templates/server.go

@@ -14,7 +14,7 @@ var ServerDecodeTemplate = `
 			return nil, errors.Wrapf(err, "cannot read body of http request")
 		}
 		if len(buf) > 0 {
-			if err = json.Unmarshal(buf, &req); err != nil {
+			if err = jsonpb.UnmarshalString(string(buf), &req); err != nil {
 				const size = 8196
 				if len(buf) > size {
 					buf = buf[:size]
@@ -67,6 +67,9 @@ import (
 	"strings"
 	"io"
 
+	"github.com/golang/protobuf/jsonpb"
+	"github.com/golang/protobuf/proto"
+
 	"context"
 
 	"github.com/gorilla/mux"
@@ -173,9 +176,12 @@ func (h httpError) Headers() http.Header {
 // EncodeHTTPGenericResponse is a transport/http.EncodeResponseFunc that encodes
 // the response as JSON to the response writer. Primarily useful in a server.
 func EncodeHTTPGenericResponse(_ context.Context, w http.ResponseWriter, response interface{}) error {
-	encoder := json.NewEncoder(w)
-	encoder.SetEscapeHTML(false)
-	return encoder.Encode(response)
+	marshaller := jsonpb.Marshaler{
+		EnumsAsInts:  true,
+		EmitDefaults: true,
+	}
+
+	return marshaller.Marshal(w, response.(proto.Message))
 }
 
 // Helper functions

gengokit/httptransport/templates_test.go

@@ -163,7 +163,7 @@ func DecodeHTTPSumZeroRequest(_ context.Context, r *http.Request) (interface{},
 		return nil, errors.Wrapf(err, "cannot read body of http request")
 	}
 	if len(buf) > 0 {
-		if err = json.Unmarshal(buf, &req); err != nil {
+		if err = jsonpb.UnmarshalString(string(buf), &req); err != nil {
 			const size = 8196
 			if len(buf) > size {
 				buf = buf[:size]