#!@PERL@
# Remove entries older than a given time from
# a DB file produced by dns-terror.
#
# 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 File::Basename;
use Time::localtime;
use Getopt::Std;

use vars qw($opt_d $opt_m $opt_v);

main();
exit(0);

sub main
{
    my(%input, $dbfile, %output, $path, $newfile,
     $days, $timestamp, $deltime, $ipaddr, $data, $domain, $expired, $total);

    getopts("d:m:v") || die "Usage: $0 [-v] [-d days] [-m mark-size] [ip2host.db]\n";
    $days = $opt_d || 35;	# Long enough to last to the next monthly report.
    $deltime = time - $days * (60 * 60 * 24);
    $dbfile = shift @ARGV || "ip2host.db";
    $path = (fileparse($dbfile, ".db"))[1];
    $newfile = "${path}tmphost.db";
    unlink $newfile;
    $| = 1;			# Instant gratification if output is logged.

    tie(%input, "BerkeleyDB::Btree", -Filename => $dbfile)
	|| die "$0: Can't tie to $dbfile: $!\n";
    tie(%output, "BerkeleyDB::Btree", -Filename => $newfile,
	-Flags => DB_CREATE|DB_TRUNCATE, -Mode => 0640)
	|| die "$0: Can't tie to $newfile: $!\n";

    $expired = $total = 0;
    # We copy to a new file because deleting while walking the btree
    # sometimes causes the DB library to SEGV.
    while (($ipaddr, $data) = each(%input)) {
	($timestamp, $domain) = unpack("IA*", $data);
	if ($timestamp < $deltime) {
	    print "deleting ", ctime($timestamp), " $ipaddr $domain\n"
		if $opt_v;
	    $expired++;
	} else {
	    $output{$ipaddr} = $data;
	}
	$total++;

	if ($opt_m and $total % $opt_m == 0) {
	    print "$total entries checked\n";
	}
    }
    
    print "Finished expiring, renaming $newfile to $dbfile\n" if $opt_v;
    untie(%input);
    untie(%output);
    rename($newfile, $dbfile)
	|| die "$0: Can't rename $newfile to $dbfile: $!\n";

    printf("Expired $expired of $total (%.2f%%) entries.\n",
	   $total ? ((100.0 * $expired) / (1.0 * $total)) : 0);
}