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 autodie;
   9
  10 use IO::Socket::INET;
  11 use File::Slurp;
  12 use Data::Dump qw/dump/;
  13
  14 use lib 'lib';
  15 use Net::DHCP::Packet;
  16 use Net::DHCP::Constants 0.67;
  17 die "need to run $0 as root like this\nsudo $0\n" unless $< == 0;
  18
  19 my $debug = shift @ARGV;
  20
  21 our ( $file, $gpxe_file );
  22 our ( $ip_from, $ip_to ) = ( 10, 100 );
  23
  24 our $server_ip = readlink 'conf/server.ip' if -l 'conf/server.ip';
  25
  26 if ( ! $server_ip ) {
  27         $server_ip = `/sbin/ifconfig`;
  28         $server_ip =~ s/^.+?addr:([\d\.]+).*$/$1/gs;
  29         warn "auto-configure server ip to $server_ip\n";
  30 } else {
  31         warn "server ip $server_ip\n";
  32 }
  33
  34 my $sock = IO::Socket::INET->new(
  35         LocalPort       => 67,
  36 #       LocalAddr       => 'localhost',
  37 #       LocalAddr       => '10.0.0.100',
  38         LocalAddr       => '0.0.0.0',
  39         Proto           => 'udp',
  40         ReuseAddr       => 1,
  41 #       PeerPort        => getservbyname('bootpc', 'udp'),
  42         Broadcast       => 1,
  43         Type            => SOCK_DGRAM,
  44 ) or die "Failed to bind to socket: $@";
  45
  46
  47 my $addr = $ip_from;
  48
  49 sub client_ip {
  50         my ( $mac ) = @_;
  51
  52         my $conf = "conf/$server_ip";
  53         mkdir $conf unless -e $conf;
  54
  55         if ( -e "$conf/mac/$mac" ) {
  56                 my $ip = read_file "$conf/mac/$mac";
  57                 print "$mac old $ip\n";
  58                 return $ip;
  59         }
  60
  61         mkdir $_ foreach grep { ! -e $_ } map { "$conf/$_" } ( 'ip', 'mac' );
  62
  63         my $prefix = $server_ip;
  64         $prefix =~ s{\.\d+$}{.};
  65         my $ip = $prefix . $addr;
  66         while ( -e "conf/ip/$ip" ) {
  67                 $ip = $prefix . $addr++;
  68                 die "all addresses allocated!" if $addr == $ip_to;
  69         }
  70
  71         write_file "$conf/mac/$mac", $ip;
  72         if ( -l "$conf/ip/$ip" && readlink "$conf/ip/$ip" ne "$conf/mac/$mac") {
  73                 unlink     "$conf/ip/$ip";
  74                 symlink    "$conf/mac/$mac", "$conf/ip/$ip";
  75                 warn "$mac IP changed to $ip";
  76         }
  77
  78         print "$mac NEW $ip\n";
  79
  80         return $ip;
  81 }
  82
  83 my $transaction = 0; # FIXME predictible transaction numbers
  84
  85 while (1) {
  86
  87         require "config.pl"; # refresh config
  88
  89         print "waiting for DHCP requests on ",$sock->sockhost,":",$sock->sockport,"\n";
  90
  91         my $buf;
  92         $sock->recv($buf, 1024);
  93         print "<< ",$sock->peerhost,":",$sock->peerport,"\n";
  94
  95         if (defined $buf) {
  96
  97                 my $dhcp = Net::DHCP::Packet->new($buf);
  98                 $dhcp->comment( $transaction++ );
  99
 100                 warn "recv: ", $dhcp->toString, "\n\n";
 101
 102                 my $mac = substr($dhcp->chaddr(),0,$dhcp->hlen()*2);
 103                 my $ip = client_ip($mac);
 104                 my $user_class = $dhcp->getOptionValue(DHO_USER_CLASS());
 105
 106                 if ( $user_class eq 'gPXE' ) {
 107                         $file = $gpxe_file;
 108                 } elsif ( ! $file ) {
 109                         $file = 'undionly.kpxe';
 110                 }
 111
 112                 my $packet = {
 113                         Op              => BOOTREPLY(),
 114                         Hops    => $dhcp->hops(),
 115                         Xid             => $dhcp->xid(),
 116                         Flags   => $dhcp->flags(),
 117                         Ciaddr  => $dhcp->ciaddr(),
 118                         Yiaddr  => $ip,
 119                         Siaddr  => $server_ip,
 120                         Giaddr  => $dhcp->giaddr(),
 121                         Chaddr  => $dhcp->chaddr(),
 122                         File    => $file,
 123 #                       DHO_DHCP_MESSAGE_TYPE() => DHCPACK(),
 124 #                       DHO_SUBNET_MASK() => '255.255.255.0',
 125                 };
 126
 127                 my $messagetype = $dhcp->getOptionValue(DHO_DHCP_MESSAGE_TYPE());
 128
 129                 if ($messagetype eq DHCPDISCOVER()) {
 130                         warn "DHCP DISCOVER";
 131                         $packet->{Comment} = $dhcp->comment();
 132                         $packet->{DHO_DHCP_MESSAGE_TYPE()} = DHCPOFFER();
 133                 } elsif ($messagetype eq DHCPREQUEST()) {
 134                         my $requested_ip = $dhcp->getOptionValue(DHO_DHCP_REQUESTED_ADDRESS());
 135                         warn "DHCP REQUEST $requested_ip";
 136                         if ( $ip eq $requested_ip ) {
 137                                 $packet->{DHO_DHCP_MESSAGE_TYPE()} = DHCPACK();
 138                                 $packet->{DHO_DHCP_LEASE_TIME()}   = 100;
 139                         } else {
 140                                 $packet->{DHO_DHCP_MESSAGE_TYPE()} = DHCPNAK();
 141                                 $packet->{DHO_DHCP_MESSAGE()} = "Bad request, expected $ip";
 142                         }
 143                 } elsif ($messagetype eq DHCPINFORM()) {
 144                         warn "DHCP INFORM ignored";
 145                 } else {
 146                         warn "$messagetype igored (bootp?)";
 147                 }
 148
 149
 150                 warn ">> $mac == $ip server: $server_ip", $file ? " file: $file\n" : "\n";
 151
 152                 $packet = new Net::DHCP::Packet( %$packet );
 153                 warn "## ",$packet->toString(),"\n" if $debug;
 154
 155                 my $reply = IO::Socket::INET->new(
 156                         LocalAddr => $server_ip,
 157                         LocalPort => 67,
 158                         Proto => "udp",
 159                         Broadcast => 1,
 160                         PeerAddr => '255.255.255.255',
 161                         PeerPort => 68,
 162                         Reuse => 1,
 163                 ) or die "socket: $@";
 164
 165                 my $buff = $packet->serialize();
 166                 $reply->send( $buff, 0 ) or die "Error sending: $!\n";
 167
 168 #               system("arp -s $ip $mac"),
 169
 170         } else {
 171                 print "No bootp request.\n";
 172         }
 173
 174 }