use strict;

use IO::Socket;
use Net::DHCP::Packet;
use Net::DHCP::Constants;

my $server_ip = "10.10.10.1";
my $client_ip = "10.10.10.10";
my $subnet_mask = "255.255.255.0";

my $socket_in = IO::Socket::INET->new(
                                        LocalPort => 67,
                                        LocalAddr => "255.255.255.255",
                                        Proto    => 'udp') or die $@;

while(1) {
  my $buf;
  $socket_in->recv($buf,4096);
  my $packet = new Net::DHCP::Packet($buf);

  my $messagetype = $packet->getOptionValue(DHO_DHCP_MESSAGE_TYPE());

  if ($messagetype eq DHCPDISCOVER()) {
                  send_offer($packet);
  } elsif ($messagetype eq DHCPREQUEST()) {
                  send_ack($packet);
  }
}

sub send_offer {
  my($request)=@_;

  my $socket_out = IO::Socket::INET->new(
                                          PeerPort => 68,
                                          PeerAddr => "255.255.255.255",
                                          LocalAddr => "$server_ip:67",
                                          Broadcast => 1,
                                          Proto    => 'udp') or die $@;

  my $offer = new Net::DHCP::Packet(
                                     Op => BOOTREPLY(),
                                     Xid => $request->xid(),
                                     Flags => $request->flags(),
                                     Ciaddr => $request->ciaddr(),
                                     Yiaddr => $client_ip,
                                     Siaddr => $server_ip,
                                     Giaddr => $request->giaddr(),
                                     Chaddr => $request->chaddr(),
                                     DHO_DHCP_MESSAGE_TYPE() => DHCPOFFER(),
                                   );

  $offer->addOptionValue(DHO_SUBNET_MASK(), $subnet_mask);
  $offer->addOptionValue(DHO_NAME_SERVERS, $server_ip);

  $socket_out->send($offer->serialize()) or die $!;
  print STDERR "sent offer\n";
}

sub send_ack {
 print STDERR "send ack\n";
}