There is currently no way (that I am aware of) to avoid forwarding topics across the bridge. I guess the situation you’re describing is that you have publishers and subscribers on the topic /tf, for example, on both the ROS 1 and ROS 2 sides but you don’t want them to talk? If you only had /tf publishers and subscribers on the ROS 1 side, then even though it would “bridge” that topic, there would be no one listening or contributing from the ROS 2 side anyways. If this is a feature you need, then I’d ask you to open an issue about it on the ros1_bridge’s issue tracker:
As for the message rate throttling, we could implement that into the bridge, but it could also be implemented on the ROS 1 side with some of the topic tools:
http://wiki.ros.org/topic_tools/throttle
It is clearer, in my opinion, to separate the bridging and throttling code unless there is a compelling reason to combine them.
We’re always happy to have contributions, it sounds like the “blacklist” of topics on the bridge would be a useful one.