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#!/usr/bin/perl
# TODO
# * use syslog
# * runit - as also invalid DHCP packets cause library to croak()
# * error checking
use strict;
use warnings;
use Sys::Hostname;
use IO::Socket::INET;
use Net::DHCP::Constants qw/:dho_codes :dhcp_message :bootp_codes :htype_codes :dhcp_other/;
use Net::DHCP::Packet;
# populated in BEGIN
my %addOption;
my $domainnameservers = '192.0.1.2 192.0.1.50';
# Mac OS X 10.7 seems to accept space seperated entries here (no idea if others do too)
my $domainname = 'domain.foo';
my @subnets;
for (<DATA>) {
next if (/^(#|$)/);
chomp;
push @subnets, $_;
}
my $sock = IO::Socket::INET->new(
Proto => 'udp',
LocalPort => 67,
);
unless ($sock) {
print STDERR "unable to open socket: $@\n";
exit 1;
}
my $buf;
while (my $src = $sock->recv($buf, DHCP_MAX_MTU - DHCP_UDP_OVERHEAD)) {
my $sport = $sock->peerport;
next unless ($sport == 68);
# add padding to stop the library complaining
# as the packets are typically 262 bytes long
$buf .= "\x00" x (BOOTP_MIN_LEN() - length($buf))
if (length($buf) < BOOTP_MIN_LEN());
my $pac = Net::DHCP::Packet->new($buf);
next unless ($pac->isDhcp
&& $pac->op == BOOTREQUEST()
&& $pac->htype == HTYPE_FDDI()
&& $pac->getOptionValue(DHO_DHCP_MESSAGE_TYPE()) == DHCPINFORM());
my $res = Net::DHCP::Packet->new(
Op => BOOTREPLY(),
Htype => $pac->htype,
Xid => $pac->xid,
Ciaddr => $sock->peerhost,
Chaddr => $pac->chaddr,
Sname => hostname,
DHO_DHCP_MESSAGE_TYPE() => DHCPACK(),
);
foreach (split / /, $pac->getOptionValue(DHO_DHCP_PARAMETER_REQUEST_LIST())) {
&{$addOption{$_}}($res, $_)
if (defined($addOption{$_}));
}
$sock->send($res->serialize);
}
exit 0;
BEGIN {
sub OptionSubnetMask {
my ($res, $opt) = @_;
$res->addOptionValue(DHO_SUBNET_MASK(), '255.255.255.255');
}
$addOption{DHO_SUBNET_MASK()} = \&OptionSubnetMask;
sub OptionDomainName {
my ($res, $opt) = @_;
$res->addOptionValue(DHO_DOMAIN_NAME(), $domainname);
}
$addOption{DHO_DOMAIN_NAME()} = \&OptionDomainName;
sub OptionDomainNameServers {
my ($res, $opt) = @_;
$res->addOptionValue(DHO_DOMAIN_NAME_SERVERS(), $domainnameservers);
}
$addOption{DHO_DOMAIN_NAME_SERVERS()} = \&OptionDomainNameServers;
sub OptionClasslessStaticRoutes {
my ($res, $opt) = @_;
$res->addOptionValue($opt, [ map { [$_, '0.0.0.0'] } @subnets ]);
}
$addOption{121} = \&OptionClasslessStaticRoutes;
$addOption{249} = \&OptionClasslessStaticRoutes;
}
__DATA__
10.0.0.0/8
192.168.0.0/16
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