113 lines
2.3 KiB
Perl
113 lines
2.3 KiB
Perl
package App::Netdisco::Util::DNS;
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use strict;
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use warnings;
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use Dancer ':script';
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use Net::DNS;
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use NetAddr::IP::Lite ':lower';
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use base 'Exporter';
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our @EXPORT = ();
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our @EXPORT_OK = qw/hostname_from_ip ipv4_from_hostname/;
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our %EXPORT_TAGS = (all => \@EXPORT_OK);
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=head1 NAME
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App::Netdisco::Util::DNS
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=head1 DESCRIPTION
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A set of helper subroutines to support parts of the Netdisco application.
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There are no default exports, however the C<:all> tag will export all
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subroutines.
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=head1 EXPORT_OK
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=head2 hostname_from_ip( $ip, \%opts? )
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Given an IP address (either IPv4 or IPv6), return the canonical hostname.
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C<< %opts >> can override the various timeouts available in
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L<Net::DNS::Resolver>:
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=over 4
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=item C<tcp_timeout>: 120 (seconds)
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=item C<udp_timeout>: 30 (seconds)
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=item C<retry>: 4 (attempts)
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=item C<retrans>: 5 (timeout)
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=back
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Returns C<undef> if no PTR record exists for the IP.
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=cut
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sub hostname_from_ip {
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my ($ip, $opts) = @_;
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return unless $ip;
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my $ETCHOSTS = setting('dns')->{'ETCHOSTS'};
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# check /etc/hosts file and short-circuit if found
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foreach my $name (reverse sort keys %$ETCHOSTS) {
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if ($ETCHOSTS->{$name}->[0]->[0] eq $ip) {
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return $name;
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}
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}
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my $res = Net::DNS::Resolver->new;
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$res->tcp_timeout($opts->{tcp_timeout} || 120);
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$res->udp_timeout($opts->{udp_timeout} || 30);
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$res->retry($opts->{retry} || 4);
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$res->retrans($opts->{retrans} || 5);
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my $query = $res->search($ip);
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if ($query) {
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foreach my $rr ($query->answer) {
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next unless $rr->type eq "PTR";
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return $rr->ptrdname;
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}
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}
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return undef;
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}
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=head2 ipv4_from_hostname( $name )
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Given a host name will return the first IPv4 address.
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Returns C<undef> if no A record exists for the name.
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=cut
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sub ipv4_from_hostname {
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my $name = shift;
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return unless $name;
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my $ETCHOSTS = setting('dns')->{'ETCHOSTS'};
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# check /etc/hosts file and short-circuit if found
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if (exists $ETCHOSTS->{$name} and $ETCHOSTS->{$name}->[0]->[0]) {
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my $ip = NetAddr::IP::Lite->new($ETCHOSTS->{$name}->[0]->[0]);
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return $ip->addr if $ip and $ip->bits == 32;
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}
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my $res = Net::DNS::Resolver->new;
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my $query = $res->search($name);
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if ($query) {
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foreach my $rr ($query->answer) {
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next unless $rr->type eq "A";
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return $rr->address;
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}
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}
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return undef;
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}
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1;
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