rpc: improve error codes for internal server errors

rpc/errors.go

@@ -62,6 +62,7 @@ const (
 	errcodeNotificationsUnsupported = -32001
 	errcodePanic                    = -32603
 	errcodeMarshalError             = -32603
+	errorcodeInternalServerError    = -32603
 )
 
 type methodNotFoundError struct{ method string }

rpc/handler.go

@@ -390,7 +390,14 @@ func (h *handler) handleSubscribe(cp *callProc, msg *jsonrpcMessage) *jsonrpcMes
 func (h *handler) runMethod(ctx context.Context, msg *jsonrpcMessage, callb *callback, args []reflect.Value) *jsonrpcMessage {
 	result, err := callb.call(ctx, msg.Method, args)
 	if err != nil {
-		return msg.errorResponse(err)
+		if ec, ok := err.(Error); ok {
+			return msg.errorResponse(ec)
+		} else {
+			return msg.errorResponse(&internalServerError{
+				code: errorcodeInternalServerError,
+				message: err.Error(),
+			})
+		}
 	}
 	return msg.response(result)
 }

rpc/json.go

@@ -95,7 +95,7 @@ func (msg *jsonrpcMessage) String() string {
 	return string(b)
 }
 
-func (msg *jsonrpcMessage) errorResponse(err error) *jsonrpcMessage {
+func (msg *jsonrpcMessage) errorResponse(err Error) *jsonrpcMessage {
 	resp := errorMessage(err)
 	resp.ID = msg.ID
 	return resp
@@ -109,15 +109,12 @@ func (msg *jsonrpcMessage) response(result interface{}) *jsonrpcMessage {
 	return &jsonrpcMessage{Version: vsn, ID: msg.ID, Result: enc}
 }
 
-func errorMessage(err error) *jsonrpcMessage {
+func errorMessage(err Error) *jsonrpcMessage {
 	msg := &jsonrpcMessage{Version: vsn, ID: null, Error: &jsonError{
 		Code:    errcodeDefault,
 		Message: err.Error(),
 	}}
-	ec, ok := err.(Error)
-	if ok {
-		msg.Error.Code = ec.ErrorCode()
-	}
+	msg.Error.Code = err.ErrorCode()
 	de, ok := err.(DataError)
 	if ok {
 		msg.Error.Data = de.ErrorData()

rpc/server_test.go

@@ -45,7 +45,7 @@ func TestServerRegisterName(t *testing.T) {
 		t.Fatalf("Expected service calc to be registered")
 	}
 
-	wantCallbacks := 12
+	wantCallbacks := 13
 	if len(svc.callbacks) != wantCallbacks {
 		t.Errorf("Expected %d callbacks for service 'service', got %d", wantCallbacks, len(svc.callbacks))
 	}

rpc/testdata/internal-error.js

@@ -5,3 +5,6 @@
 
 --> {"jsonrpc":"2.0","id":2,"method":"test_panic","params": []}
 <-- {"jsonrpc":"2.0","id":2,"error":{"code":-32603,"message":"method handler crashed"}}
+
+--> {"jsonrpc":"2.0","id":2,"method":"test_returnInternalError","params": []}
+<-- {"jsonrpc":"2.0","id":2,"error":{"code":-32603,"message":"service internal error"}}

rpc/testservice_test.go

@@ -120,6 +120,10 @@ func (s *testService) ReturnError() error {
 	return testError{}
 }
 
+func (s *testService) ReturnInternalError() error {
+	return errors.New("service internal error")
+}
+
 func (s *testService) MarshalError() *MarshalErrObj {
 	return &MarshalErrObj{}
 }