Compute bloom filter for reverse lookup to enable bulk local address filtering

[davidmurdoch]

I'd love to be able to make an eth_call to return a bloom filter containing all registered addresses (and maybe another filter for all registered domains, but that's less useful for my purposes)

If I have dozens of local addresses and would like to fetch their ens records (if reverse ens is enabled) I have to make dozens of queries to do so. It'd be nice if I could query for the latest bloom filter, then check if the addresses are contained in the filter; that way I'd only query for addresses that are very likely (due to bloom filter false positives) to be registered.

Of course, maybe there already is an efficient way of doing bulk reverse lookup and this issue should be closed :-)