#!/usr/bin/perl

package Pos::Webtop::Dns;

use strict;
use Pos::db;
use Net::DNS::Resolver;

=head1 NAME

Pos::Webtop::DNS -- DNS resolution per-company webserver with fallback support.

=head1 SYNOPSIS

my $dottedQuadIp = Pos::Webtop::Dns::posdnsResolveHost(
				db        => $db, 
				companyId => 16,
				host      => 'www.yahoo.com');

=cut

sub posdnsResolveHost {
	my ($host, $resolver, $tb) = @{{@_}}{qw/host resolver toolBox/};
	my $addr = undef;
	my $clean = 0;
	my $ip = undef;
	my $supernattedIp = undef;
	my $db = $tb->getWebtopDbWriter();
	my $client = $tb->getClient();
	my $webSessionId = $client->getSessionId();
	my $companyId = $client->getCustomerId();

	if (not defined($resolver)) {
	
		$resolver = Net::DNS::Resolver->new or return undef;

		my @nameservers = $db->query(sql => "
				select
					RAWIP32_TO_DOTTED_QUAD_NO(dns_server_act_address)
				from
					customer_dns_servers
				where
					customer_id = '" . $db->escape(dirty => $companyId) . "'
				");

		if (scalar(@nameservers) == 0) { return undef; }				
		
		$ip = $nameservers[0];

		# acquire a supernat for this ip... 
		# if we have a web session, make it a web session nat, else, backend dynamic...
		
		if ( defined($webSessionId) )
		{
			$supernattedIp = $tb->getSupernattedIp( host=> $ip );
		}
		else
		{
			$supernattedIp = $tb->getSupernatInternalAddress( webSessionNat=> 0, ip=> $nameservers[0] );
		}		

		if ( not defined $supernattedIp )
		{
			$client->logger( severity=>'WARNING', logMessage=>'WEBTOP Dns: Supernat failed!' );
			return undef;
		}

		if ( $supernattedIp =~ /^((?:\d+\.){3}\d+)$/ )
		{
			$supernattedIp = $1;
		}
		else
		{
			warn "Pos::Webtop::Dns::posdnsResolveHost(): Got invalid ip from supernat request: '$supernattedIp'; returning undef";
			return undef;
		}

		$resolver->{'nameservers'} = [ $supernattedIp ];

	} else {
		$clean = 1;
	}

	my $response = $resolver->query($host);

	if ( defined($supernattedIp) && !defined($webSessionId) )
	{
		# must free backend dynamic nat
		Pos::Webtop::Supernat::supernatReleaseDynamicBackendNat( db=> $db, companyId=> $companyId, actualAddress=> $ip );
	}

	if ( defined($response) )
	{
		foreach my $answer ($response->answer) {

			if ($answer->{"class"} ne 'IN') { next; }
			if ($answer->{"type"} ne 'A') { next; }

			$addr = $answer->rdatastr;
		}
	}

	if (($clean == 0) and not defined($addr)) {
		
		# try one more time with global dns
		$addr = Pos::Webtop::Dns::posdnsResolveHost(toolBox => $tb, host => $host, resolver => Net::DNS::Resolver->new);

	}

	return $addr;
}

1;