#!@PERL@
# Retry resolving negative cache entries in the IP to host name DB file.
#
# Written by David MacKenzie <djm@djmnet.org>
# Please send comments and bug reports to <fastresolve-bugs@djmnet.org>

##############################################################################
#   Copyright 1999 UUNET, an MCI WorldCom company.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2, or (at your option)
# any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
# 02111-1307, USA.
##############################################################################

use BerkeleyDB;
use Fcntl;
use Getopt::Std;

use vars qw($opt_d);

main();
exit(0);

sub main
{
    my(@opts, $dbfile, $tempfile);

    @opts = @ARGV;
    getopts("d:");

    $dbfile = $opt_d || "ip2host.db";
    ($tempfile = $dbfile) =~ s/\.db$//;
    $tempfile .= ".temp$$";

    $SIG{HUP} = $SIG{INT} = $SIG{TERM} = sub { unlink $tempfile; exit 1; };
    get_unresolved($dbfile, $tempfile);
    system "dns-terror @opts -r < $tempfile";
    unlink $tempfile;
}

# Put the unresolved addresses in $dbfile into $outfile, one per line.
sub get_unresolved
{
    my($dbfile, $outfile) = @_;
    my(%input, $timestamp, $key, $data);

    tie(%input, "BerkeleyDB::Btree", -Filename => $dbfile, -Flags => DB_RDONLY)
	|| die "$0: Can't read $dbfile: $!\n";
    
    open(OUT, ">$outfile") || die "$0: Can't create $outfile: $!\n";

    while (($key, $data) = each(%input)) {
	($timestamp, $data) = unpack("IA*", $data);

	if (!$data) {
	    print OUT "$key\n";
	}
    }
    
    untie(%input);
    close(OUT);
}