Return E_PARSE error when JSON can't be parsed

v2/json2/json_test.go

@@ -10,6 +10,7 @@ import (
 	"encoding/json"
 	"errors"
 	"net/http"
+	"strings"
 	"testing"
 
 	"github.com/gorilla/rpc/v2"
@@ -136,6 +137,16 @@ func executeRaw(t *testing.T, s *rpc.Server, req interface{}, res interface{}) e
 	return DecodeClientResponse(w.Body, res)
 }
 
+func executeInvalidJSON(t *testing.T, s *rpc.Server, res interface{}) error {
+	r, _ := http.NewRequest("POST", "http://localhost:8080/", strings.NewReader(`not even a json`))
+	r.Header.Set("Content-Type", "application/json")
+
+	w := NewRecorder()
+	s.ServeHTTP(w, r)
+
+	return DecodeClientResponse(w.Body, res)
+}
+
 func TestService(t *testing.T) {
 	s := rpc.NewServer()
 	s.RegisterCodec(NewCodec(), "application/json")
@@ -182,6 +193,15 @@ func TestService(t *testing.T) {
 	if res.Result != Service1DefaultResponse {
 		t.Errorf("Wrong response: got %v, want %v", res.Result, Service1DefaultResponse)
 	}
+
+	res = Service1Response{}
+	if err := executeInvalidJSON(t, s, &res); err == nil {
+		t.Error("Expected to receive an E_PARSE error, but got nil")
+	} else if jsonRpcErr, ok := err.(*Error); !ok {
+		t.Errorf("Expected to receive an Error, but got %T: %s", err, err)
+	} else if jsonRpcErr.Code != E_PARSE {
+		t.Errorf("Expected to receive an E_PARSE JSON-RPC error (%d) but got %d", E_PARSE, jsonRpcErr.Code)
+	}
 }
 
 func TestDecodeNullResult(t *testing.T) {

v2/json2/server.go

@@ -88,20 +88,21 @@ func newCodecRequest(r *http.Request, encoder rpc.Encoder) rpc.CodecRequest {
 	// Decode the request body and check if RPC method is valid.
 	req := new(serverRequest)
 	err := json.NewDecoder(r.Body).Decode(req)
+
 	if err != nil {
 		err = &Error{
 			Code:    E_PARSE,
 			Message: err.Error(),
 			Data:    req,
 		}
-	}
-	if req.Version != Version {
+	} else if req.Version != Version {
 		err = &Error{
 			Code:    E_INVALID_REQ,
 			Message: "jsonrpc must be " + Version,
 			Data:    req,
 		}
 	}
+
 	r.Body.Close()
 	return &CodecRequest{request: req, err: err, encoder: encoder}
 }
@@ -185,8 +186,9 @@ func (c *CodecRequest) WriteError(w http.ResponseWriter, status int, err error)
 }
 
 func (c *CodecRequest) writeServerResponse(w http.ResponseWriter, res *serverResponse) {
-	// Id is null for notifications and they don't have a response.
-	if c.request.Id != nil {
+	// Id is null for notifications and they don't have a response, unless we couldn't even parse the JSON, in that
+	// case we can't know whether it was intended to be a notification
+	if c.request.Id != nil || isParseErrorResponse(res) {
 		w.Header().Set("Content-Type", "application/json; charset=utf-8")
 		encoder := json.NewEncoder(c.encoder.Encode(w))
 		err := encoder.Encode(res)
@@ -198,5 +200,9 @@ func (c *CodecRequest) writeServerResponse(w http.ResponseWriter, res *serverRes
 	}
 }
 
+func isParseErrorResponse(res *serverResponse) bool {
+	return res != nil && res.Error != nil && res.Error.Code == E_PARSE
+}
+
 type EmptyResponse struct {
 }