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lib/Net/DNS/Resolver/cygwin.pm  view on Meta::CPAN

package Net::DNS::Resolver::cygwin;

use strict;
use warnings;
our $VERSION = (qw$Id: cygwin.pm 2002 2025-01-07 09:57:46Z willem $)[2];


=head1 NAME

Net::DNS::Resolver::cygwin - Cygwin resolver class

=cut


use IO::File;


sub _getregkey {
	my @key = @_;

	my $handle = IO::File->new( join( '/', @key ), '<' ) or return '';
	my $value  = <$handle> || '';
	close($handle);

	$value =~ s/\0+$//;
	return $value;
}


sub _init {
	my $defaults = shift->_defaults;

	my $dirhandle;

	my $root = '/proc/registry/HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Services/Tcpip/Parameters';

	unless ( -d $root ) {

		# Doesn't exist, maybe we are on 95/98/Me?
		$root = '/proc/registry/HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Services/VxD/MSTCP';
		-d $root || Carp::croak "can't read registry: $!";
	}

	# Best effort to find a useful domain name for the current host
	# if domain ends up blank, we're probably (?) not connected anywhere
	# a DNS server is interesting either...
	my $domain = _getregkey( $root, 'Domain' ) || _getregkey( $root, 'DhcpDomain' );

	# If nothing else, the searchlist should probably contain our own domain
	# also see below for domain name devolution if so configured
	# (also remove any duplicates later)
	my $devolution = _getregkey( $root, 'UseDomainNameDevolution' );
	my $searchlist = _getregkey( $root, 'SearchList' );
	my @searchlist = ( $domain, split m/[\s,]+/, $searchlist );


	# This is (probably) adequate on NT4
	my @nt4nameservers;
	foreach ( grep {length} _getregkey( $root, 'NameServer' ), _getregkey( $root, 'DhcpNameServer' ) ) {
		push @nt4nameservers, split m/[\s,]+/;
		last;
	}


	# but on W2K/XP the registry layout is more advanced due to dynamically
	# appearing connections. So we attempt to handle them, too...
	# opt to silently fail if something isn't ok (maybe we're on NT4)
	# If this doesn't fail override any NT4 style result we found, as it
	# may be there but is not valid.
	# drop any duplicates later
	my @nameservers;

	my $dnsadapters = join '/', $root, 'DNSRegisteredAdapters';
	if ( opendir( $dirhandle, $dnsadapters ) ) {
		my @adapters = grep { !/^\.\.?$/ } readdir($dirhandle);
		closedir($dirhandle);
		foreach my $adapter (@adapters) {
			my $ns = _getregkey( $dnsadapters, $adapter, 'DNSServerAddresses' );
			until ( length($ns) < 4 ) {
				push @nameservers, join '.', unpack( 'C4', $ns );
				substr( $ns, 0, 4 ) = '';
			}
		}
	}

	my $interfaces = join '/', $root, 'Interfaces';
	if ( opendir( $dirhandle, $interfaces ) ) {
		my @ifacelist = grep { !/^\.\.?$/ } readdir($dirhandle);
		closedir($dirhandle);
		foreach my $iface (@ifacelist) {
			my $ip = _getregkey( $interfaces, $iface, 'DhcpIPAddress' )
					|| _getregkey( $interfaces, $iface, 'IPAddress' );
			next unless $ip;
			next if $ip eq '0.0.0.0';

			foreach (
				grep {length} _getregkey( $interfaces, $iface, 'NameServer' ),
				_getregkey( $interfaces, $iface, 'DhcpNameServer' )
				) {
				push @nameservers, split m/[\s,]+/;
				last;
			}
		}
	}

	@nameservers = @nt4nameservers unless @nameservers;
	$defaults->nameservers(@nameservers);


	# fix devolution if configured, and simultaneously
	# eliminate duplicate entries (but keep the order)
	my @list;
	my %seen;
	foreach (@searchlist) {
		s/\.+$//;
		push( @list, $_ ) unless $seen{lc $_}++;

		next unless $devolution;

		# while there are more than two labels, cut
		while (s#^[^.]+\.(.+\..+)$#$1#) {
			push( @list, $_ ) unless $seen{lc $_}++;
		}
	}
	$defaults->searchlist(@list);

	%$defaults = Net::DNS::Resolver::Base::_untaint(%$defaults);

	$defaults->_read_env;
	return;
}


1;
__END__


=head1 SYNOPSIS

	use Net::DNS::Resolver;

=head1 DESCRIPTION

This class implements the OS specific portions of C<Net::DNS::Resolver>.

No user serviceable parts inside, see L<Net::DNS::Resolver>
for all your resolving needs.

=head1 COPYRIGHT

Copyright (c)2003 Sidney Markowitz.

All rights reserved.

=head1 LICENSE

Permission to use, copy, modify, and distribute this software and its
documentation for any purpose and without fee is hereby granted, provided
that the original copyright notices appear in all copies and that both
copyright notice and this permission notice appear in supporting