For the DoS mitigation subsystem (legacy/trac#24902), we need a way to lookup the connection address and *quickly* know if it is a known relay or not. This is also needed for legacy/trac#2667 which would prevent Exit to reenter the network. nickm has started a branch to have IP addresses with bloom filter: `address_set_029`. Next step is to use that and bridge it with the nodelist so we can lookup an IP address and learn if it is known or not (not get the `node_t` back, that would require more work and probably lose in performance).