[rbldnsd] /32 listings and exclusions on ip4trie -> possible troubles

[furio ercolessi]

If a dataset contains a /32 listing and also an exclusion for that IP,
then using ip4trie for that dataset may lead to troubles.
The IP will appear listed if the /32 listing comes first in the
file, or unlisted if the exclusion comes first.  The record that
comes first takes the slot, and the other is tossed away.
This behavior may lead to unintended results.

I think this is OK once people are fully aware of this, but perhaps
the documentation should stress this point.
Or perhaps the code can be fixed by giving priority to the exclusion
(that is, if the slot for the IP is occupied by a listing and an
exclusion appears, the exclusion could be put in place of the listing),
but I do not know if such behavior would break other things.

furio