the acl.c code parsing a site-spec has been factored out into a
new TU: hostspec. it was superior to the parsing code in
upstream.c in that it properly deals with both ipv4 and ipv6.
both upstream and acl now use the new code for parsing, and upstream
also for checking for a match.
acl.c still uses the old matching code as it has a lot of special case
code for specifications containing a hostname, and in case such
a spec is encountered, tries to do reverse name lookup to see if
a numeric ip matches that spec.
removing that code could break existing usecases, however since
that was never implemented for upstream nobody will miss it there.
original patch submitted in 2006 to debian mailing list:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=392848%29#12
this version was rebased to git and updated by Russ Dill <russ.dill@gmail.com>
in 2015 (the original patch used a different config file format).
as discussed in #40.
commit message by @rofl0r.
