protovalidate: don't panic in streaming interceptor

The streaming interceptor should match the behavior of the unary
interceptor and gracefully handle non-protobuf messages.

Signed-off-by: Akshay Shah <[email protected]>

Author: akshayjshah

interceptors/protovalidate/protovalidate.go

@@ -63,7 +63,10 @@ func (w *wrappedServerStream) RecvMsg(m interface{}) error {
 		return err
 	}
 
-	msg := m.(proto.Message)
+	msg, ok := m.(proto.Message)
+	if !ok {
+		return errors.New("unsupported message type")
+	}
 	if w.options.shouldIgnoreMessage(msg.ProtoReflect().Type()) {
 		return nil
 	}

interceptors/protovalidate/protovalidate_test.go

@@ -45,6 +45,12 @@ func TestUnaryServerInterceptor(t *testing.T) {
 		assert.Equal(t, codes.InvalidArgument, status.Code(err))
 	})
 
+	t.Run("not_protobuf", func(t *testing.T) {
+		_, err = interceptor(context.Background(), "not protobuf", info, handler)
+		assert.Error(t, err)
+		assert.Equal(t, codes.Unknown, status.Code(err))
+	})
+
 	interceptor = protovalidate_middleware.UnaryServerInterceptor(validator,
 		protovalidate_middleware.WithIgnoreMessages(testvalidate.BadUnaryRequest.ProtoReflect().Type()),
 	)