sub split_domain { my $domain = shift; my ( $sld, $subtld, $tld ); if ( $domain =~ s/\.9\.4\.e164\.arpa$//o ) { ( $sld, $subtld, $tld ) = ( $domain, '', '9.4.e164.arpa' ); } else { ( $sld, $subtld, $tld ) = split /\./, $domain; ( $subtld, $tld ) = ( "", $subtld ) unless $tld; } [...]