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#!/usr/bin/perl -w
#------------------------------------------------------------------------------
# Usage: mresolv2 [ -t timeout ] [ file... ]
#
# Reads IP addresses and issues non-blocking DNS queries. Answers are
# sent to standard output in RR format:
#
# 1.1.168.192.in-addr.arpa. 86400 IN PTR host1.example.com.
#
# 1.2.168.192.in-addr.arpa. 86400 IN CNAME 1.0-16.2.168.192.in-addr.arpa.
# 1.0-16.2.168.192.in-addr.arpa. 86400 IN PTR host2.example.com.
#
# Michael Fuhr
# mike@fuhr.org
#
# Copyright (c) 1999-2000 Michael Fuhr. All rights reserved. This program
# is free software; you can redistribute it and/or modify it under the same
# terms as Perl itself.
#
# $Id: mresolv2,v 1.3 2000/11/24 17:14:40 mfuhr Exp mfuhr $
#------------------------------------------------------------------------------
use IO::Socket;
use IO::Select;
use Net::DNS;
use Getopt::Std;
use strict;
use constant DEFAULT_TIMEOUT => 30;
use constant DEFAULT_NAMESERVER => "127.0.0.1";
use constant DEFAULT_PORT => 53;
use constant DEFAULT_SRCADDR => "0.0.0.0";
use constant DEFAULT_SRCPORT => 0;
$| = 1;
#------------------------------------------------------------------------------
# Get the timeout or use a reasonable default.
#------------------------------------------------------------------------------
my $progname = $0;
$progname =~ s!.*/!!;
my %opt;
getopts("t:", \%opt);
my $timeout = defined($opt{"t"}) ? $opt{"t"} : DEFAULT_TIMEOUT;
die "$progname: invalid timeout: $timeout\n" if $timeout < 0;
#------------------------------------------------------------------------------
# Create a socket pointing at the default nameserver.
#------------------------------------------------------------------------------
my $sock = IO::Socket::INET->new(Proto => "udp");
die "couldn't create socket: $!" unless $sock;
my $sockaddr_src = sockaddr_in(DEFAULT_SRCPORT, inet_aton(DEFAULT_SRCADDR));
$sock->bind($sockaddr_src) or die "can't bind socket: $!";
my $res = Net::DNS::Resolver->new;
my $ns = $res->nameservers ? ($res->nameservers)[0] : DEFAULT_NAMESERVER;
my $sockaddr_dst = sockaddr_in(DEFAULT_PORT, inet_aton($ns));
my $sel = IO::Select->new;
$sel->add($sock);
#------------------------------------------------------------------------------
# Read IP addresses and send queries.
#------------------------------------------------------------------------------
my $pending = 0;
while (<>) {
chomp;
next unless /^(\d+)\.(\d+)\.(\d+)\.(\d+)$/;
my $ip = "$4.$3.$2.$1.in-addr.arpa";
my $packet = Net::DNS::Packet->new($ip, "PTR");
$sock->send($packet->data, 0, $sockaddr_dst) or die "send: $ip: $!";
++$pending;
while ($sel->can_read(0)) {
--$pending;
my $buf = "";
$sock->recv($buf, 512) or die "recv: $!";
next unless $buf;
my $ans = Net::DNS::Packet->new(\$buf);
next unless $ans;
foreach my $rr ($ans->answer) {
$rr->print;
if ($rr->type eq "CNAME") {
my $cname = $rr->cname;
my $packet = Net::DNS::Packet->new($cname, "PTR");
$sock->send($packet->data, 0, $sockaddr_dst)
or die "send: $cname: $!";
++$pending;
}
}
}
}
#------------------------------------------------------------------------------
# Wait for outstanding requests until all are complete or we've timed out.
#------------------------------------------------------------------------------
while ($pending > 0 && $sel->can_read($timeout)) {
--$pending;
my $buf = "";
$sock->recv($buf, 512) or die "recv: $!";
next unless $buf;
my $ans = Net::DNS::Packet->new(\$buf);
next unless $ans;
foreach my $rr ($ans->answer) {
$rr->print;
if ($rr->type eq "CNAME") {
my $cname = $rr->cname;
my $packet = Net::DNS::Packet->new($cname, "PTR");
$sock->send($packet->data, 0, $sockaddr_dst)
or die "send: $cname: $!";
++$pending;
}
}
}
|
