Detect registered domains with reg-dom-libs

The reg-dom libs are available in C, Perl and PHP so far.

They include recent representations of the effective TLD list available at
mxr.mozilla.org/mozilla-central/source/netwerk/dns/effective_tld_names.dat
and help to convert an arbitrary domain name to the registered domain name.

Pseudo code:
registeredDomain = getRegisteredDomain(ingoingDomain);

Return values:
1) NULL if ingoingDomain is a TLD
2) the registered domain name if TLD is known
3) just <domain>.<tld> if <tld> is unknown
   This case was added to support new TLDs in outdated reg-dom libs
   by a certain likelihood. This fallback method is implemented in the
   last conversion step and can be simply commented out.

<Apache 2.0 Licence>

Nightly updated if necessary,
download at: http://www.dkim-reputation.org/regdom-lib-downloads/

Source Code at GitHub: https://github.com/usrflo/registered-domain-libs

Contact: http://www.agitos.de/supportformular.html