variable limit_conn?

Hi,

I need to throttle traffic based on where the client is connecting from. For example, if client is 10.0.0.1, I want to limit_conn to 1; if client is 10.1.0.2, I want limit_conn to 5, ... I have a map that contains IP to # connections allowed. How can I enforce the limit_conn? lt doesn't allow me to use `limit_conn zone $num_conn`, seems to require a constant number.

Thanks!