git.rot13.org Git - pxelator/blob - bin/dhcpd.pl

   1 #!/usr/bin/perl
   2
   3 # based on http://www.perlmonks.org/index.pl?node_id=325248
   4
   5 use strict;
   6 use warnings;
   7
   8 use IO::Socket::INET;
   9 use Net::DHCP::Packet;
  10 use Net::DHCP::Constants;
  11 use Data::Dump qw/dump/;
  12
  13 die "need to run $0 as root like this\nsudo $0\n" unless $< == 0;
  14
  15 my $debug = shift @ARGV;
  16
  17 our ( $server_ip, $file, $next_file );
  18
  19 my $sock = IO::Socket::INET->new(
  20         LocalPort       => 67,
  21 #       LocalAddr       => 'localhost',
  22 #       LocalAddr       => '10.0.0.100',
  23         LocalAddr       => '0.0.0.0',
  24         Proto           => 'udp',
  25         ReuseAddr       => 1,
  26 #       PeerPort        => getservbyname('bootpc', 'udp'),
  27         Broadcast       => 1,
  28         Type            => SOCK_DGRAM,
  29 ) or die "Failed to bind to socket: $@";
  30
  31 my $_ip = 10;
  32 my $_mac2ip;
  33
  34 sub client_ip {
  35         my ( $mac ) = @_;
  36
  37         my $ip = $_mac2ip->{$mac};
  38         return $ip if $ip;
  39
  40         $ip = $server_ip;
  41         $ip =~ s{\.\d+$}{.$_ip};
  42         $_mac2ip->{$mac} = $ip;
  43
  44         $_ip++;
  45         if ( $_ip == 100 ) {
  46                 warn "IP roll-over to 10\n";
  47                 $_ip = 10;
  48         }
  49
  50         return $ip;
  51 }
  52
  53 while (1) {
  54
  55         require "config.pl"; # refresh config
  56
  57         print "waiting for DHCP requests on ",$sock->sockhost,":",$sock->sockport,"\n";
  58
  59         my $buf;
  60         $sock->recv($buf, 1024);
  61         print "<< peer:",$sock->peerhost,":",$sock->peerport,"\n";
  62
  63         if (defined $buf) {
  64
  65                 my $dhcp;
  66
  67                 eval { $dhcp = Net::DHCP::Packet->new($buf); };
  68                 die "can't use request", dump( $buf ) if $@;
  69
  70                 if ( $debug ) {
  71                         warn "recv: ", $dhcp->toString, "\n\n";
  72                 }
  73
  74                 my $mac = substr($dhcp->chaddr(),0,$dhcp->hlen()*2);
  75                 my $ip = client_ip($mac);
  76
  77                 if ( ! $file ) {
  78                         if ( $dhcp->getOptionValue(DHO_USER_CLASS()) ne 'gPXE' ) {
  79                                 $file = 'undionly.kpxe';
  80                         } else {
  81                                 $file = $next_file;
  82                         }
  83                 }
  84
  85                 my $packet = new Net::DHCP::Packet(
  86                         Op              => BOOTREPLY(),
  87                         Hops    => $dhcp->hops(),
  88                         Xid             => $dhcp->xid(),
  89                         Flags   => $dhcp->flags(),
  90                         Ciaddr  => $dhcp->ciaddr(),
  91                         Yiaddr  => $ip,
  92                         Siaddr  => $server_ip,
  93                         Giaddr  => $dhcp->giaddr(),
  94                         Chaddr  => $dhcp->chaddr(),
  95                         File    => $file,
  96 #                       DHO_DHCP_MESSAGE_TYPE() => DHCPACK(),
  97                 DHO_SUBNET_MASK() => '255.0.0.0',
  98                 );
  99
 100                 warn ">> $mac == $ip server $server_ip\n";
 101
 102                 warn "## ",$packet->toString(),"\n" if $debug;
 103
 104                 my $reply = IO::Socket::INET->new(
 105                         LocalAddr => $server_ip,
 106                         LocalPort => 67,
 107                         Proto => "udp",
 108                         Broadcast => 1,
 109                         PeerAddr => '255.255.255.255',
 110                         PeerPort => 68,
 111                         Reuse => 1,
 112                 ) or die "socket: $@";
 113
 114                 my $buff = $packet->serialize();
 115                 $reply->send( $buff, 0 ) or die "Error sending: $!\n";
 116
 117 #               system("arp -s $ip $mac"),
 118
 119         } else {
 120                 print "No bootp request.\n";
 121         }
 122
 123 }