package App::Netdisco::Util::DNS;
use strict;
use warnings FATAL => 'all';
use Net::DNS;
use base 'Exporter';
our @EXPORT = ();
our @EXPORT_OK = qw/
hostname_from_ip ipv4_from_hostname
/;
our %EXPORT_TAGS = (all => \@EXPORT_OK);
=head1 NAME
App::Netdisco::Util::DNS
=head1 DESCRIPTION
A set of helper subroutines to support parts of the Netdisco application.
There are no default exports, however the C<:all> tag will export all
subroutines.
=head1 EXPORT_OK
=head2 hostname_from_ip( $ip )
Given an IP address (either IPv4 or IPv6), return the canonical hostname.
Returns C<undef> if no PTR record exists for the IP.
=cut
sub hostname_from_ip {
my $ip = shift;
return unless $ip;
my $res = Net::DNS::Resolver->new;
my $query = $res->search($ip);
if ($query) {
foreach my $rr ($query->answer) {
next unless $rr->type eq "PTR";
return $rr->ptrdname;
}
}
return undef;
}
=head2 ipv4_from_hostname( $name )
Given a host name will return the first IPv4 address.
Returns C<undef> if no A record exists for the name.
=cut
sub ipv4_from_hostname {
my $name = shift;
return unless $name;
my $res = Net::DNS::Resolver->new;
my $query = $res->search($name);
if ($query) {
foreach my $rr ($query->answer) {
next unless $rr->type eq "A";
return $rr->address;
}
}
return undef;
}
1;