Speed up ejabberd_s2s:is_service/2, allow_host/2 (thanks to Andreas Köhler)(EJAB...

Speed up ejabberd_s2s:is_service/2, allow_host/2 (thanks to Andreas Köhler)(EJAB-1319)

Iterating through the list of possible parent domains of a given domain
and comparing with the list of hosts or routes is almost always faster
than doing it the other way around. It naturally returns the shortest or
longest parent domain satisfying a predicate, whereas the possibly long
list compared with would need to be sorted by length first.