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 use Net::Ping;
  14
  15 use lib 'lib';
  16 use Net::DHCP::Packet;
  17 use Net::DHCP::Constants 0.67;
  18 die "need to run $0 as root like this\nsudo $0\n" unless $< == 0;
  19
  20 my $debug = shift @ARGV;
  21
  22 our ( $file, $gpxe_file );
  23 our ( $ip_from, $ip_to ) = ( 10, 100 );
  24
  25 our $server_ip = readlink 'conf/server.ip' if -l 'conf/server.ip';
  26
  27 if ( ! $server_ip ) {
  28         $server_ip = `/sbin/ifconfig`;
  29         $server_ip =~ s/^.+?addr:([\d\.]+).*$/$1/gs;
  30         warn "auto-configure server ip to $server_ip\n";
  31 } else {
  32         warn "server ip $server_ip\n";
  33 }
  34
  35 my $sock = IO::Socket::INET->new(
  36         LocalPort       => 67,
  37 #       LocalAddr       => 'localhost',
  38 #       LocalAddr       => '10.0.0.100',
  39         LocalAddr       => '0.0.0.0',
  40         Proto           => 'udp',
  41         ReuseAddr       => 1,
  42 #       PeerPort        => getservbyname('bootpc', 'udp'),
  43         Broadcast       => 1,
  44         Type            => SOCK_DGRAM,
  45 ) or die "Failed to bind to socket: $@";
  46
  47
  48 my $addr = $ip_from;
  49
  50 sub client_ip {
  51         my ( $mac ) = @_;
  52
  53         my $conf = "conf/$server_ip";
  54         mkdir $conf unless -e $conf;
  55
  56         if ( -e "$conf/mac/$mac" ) {
  57                 my $ip = read_file "$conf/mac/$mac";
  58                 print "$mac old $ip\n";
  59                 return $ip;
  60         }
  61
  62         mkdir $_ foreach grep { ! -e $_ } map { "$conf/$_" } ( 'ip', 'mac' );
  63
  64         my $p = Net::Ping->new;
  65
  66         my $prefix = $server_ip;
  67         $prefix =~ s{\.\d+$}{.};
  68         my $ip = $prefix . $addr;
  69         while ( -e "conf/ip/$ip" || $p->ping( $ip ) ) {
  70                 $ip = $prefix . $addr++;
  71                 die "all addresses allocated!" if $addr == $ip_to;
  72         }
  73
  74         write_file "$conf/mac/$mac", $ip;
  75         if ( -l "$conf/ip/$ip" && readlink "$conf/ip/$ip" ne "$conf/mac/$mac") {
  76                 unlink     "$conf/ip/$ip";
  77                 symlink    "$conf/mac/$mac", "$conf/ip/$ip";
  78                 warn "$mac IP changed to $ip";
  79         }
  80
  81         print "$mac NEW $ip\n";
  82
  83         return $ip;
  84 }
  85
  86 my $transaction = 0; # FIXME predictible transaction numbers
  87
  88 while (1) {
  89
  90         require "config.pl"; # refresh config
  91
  92         print "waiting for DHCP requests on ",$sock->sockhost,":",$sock->sockport,"\n";
  93
  94         my $buf;
  95         $sock->recv($buf, 1024);
  96         print "<< ",$sock->peerhost,":",$sock->peerport,"\n";
  97
  98         if (defined $buf) {
  99
 100                 my $dhcp = Net::DHCP::Packet->new($buf);
 101                 $dhcp->comment( $transaction++ );
 102
 103                 warn "recv: ", $dhcp->toString, "\n\n";
 104
 105                 my $mac = substr($dhcp->chaddr(),0,$dhcp->hlen()*2);
 106                 my $ip = client_ip($mac);
 107                 my $user_class = $dhcp->getOptionValue(DHO_USER_CLASS());
 108
 109                 if ( $user_class eq 'gPXE' ) {
 110                         $file = $gpxe_file;
 111                 } elsif ( ! $file ) {
 112                         $file = 'undionly.kpxe';
 113                 }
 114
 115                 my $packet = {
 116                         Op              => BOOTREPLY(),
 117                         Hops    => $dhcp->hops(),
 118                         Xid             => $dhcp->xid(),
 119                         Flags   => $dhcp->flags(),
 120                         Ciaddr  => $dhcp->ciaddr(),
 121                         Yiaddr  => $ip,
 122                         Siaddr  => $server_ip,
 123                         Giaddr  => $dhcp->giaddr(),
 124                         Chaddr  => $dhcp->chaddr(),
 125                         File    => $file,
 126                 };
 127
 128                 my $messagetype = $dhcp->getOptionValue(DHO_DHCP_MESSAGE_TYPE());
 129
 130                 if ($messagetype eq DHCPDISCOVER()) {
 131                         warn "DHCP DISCOVER";
 132                         $packet->{Comment} = $dhcp->comment();
 133                         $packet->{DHO_DHCP_MESSAGE_TYPE()} = DHCPOFFER();
 134                 } elsif ($messagetype eq DHCPREQUEST()) {
 135                         my $requested_ip = $dhcp->getOptionValue(DHO_DHCP_REQUESTED_ADDRESS());
 136                         warn "DHCP REQUEST $requested_ip";
 137                         if ( $ip eq $requested_ip ) {
 138                                 $packet->{DHO_DHCP_MESSAGE_TYPE()}      = DHCPACK();
 139                                 $packet->{DHO_DHCP_LEASE_TIME()}        = 5 * 60; # 5 min
 140 #                               $packet->{DHO_DHCP_SERVER_IDENTIFIER()} = $server_ip;           # FIXME
 141                                 $packet->{DHO_SUBNET_MASK()}            = '255.255.255.0';
 142                                 $packet->{DHO_ROUTERS()}                = $server_ip;
 143 #                               $packet->{DHO_DOMAIN_NAME()}            = 'pxelator.lan';
 144 #                               $packet->{DHO_NAME_SERVERS()}           = $server_ip;
 145 #                               $packet->{DHO_ROOT_PATH()}              = '/exports/foobar';
 146                         } else {
 147                                 $packet->{DHO_DHCP_MESSAGE_TYPE()} = DHCPNAK();
 148                                 $packet->{DHO_DHCP_MESSAGE()} = "Bad request, expected $ip";
 149                         }
 150                 } elsif ($messagetype eq DHCPINFORM()) {
 151                         warn "DHCP INFORM ignored";
 152                 } else {
 153                         warn "$messagetype igored (bootp?)";
 154                 }
 155
 156
 157                 warn ">> $mac == $ip server: $server_ip", $file ? " file: $file\n" : "\n";
 158
 159                 $packet = new Net::DHCP::Packet( %$packet );
 160                 warn "## ",$packet->toString(),"\n" if $debug;
 161
 162                 my $reply = IO::Socket::INET->new(
 163                         LocalAddr => $server_ip,
 164                         LocalPort => 67,
 165                         Proto => "udp",
 166                         Broadcast => 1,
 167                         PeerAddr => '255.255.255.255',
 168                         PeerPort => 68,
 169                         Reuse => 1,
 170                 ) or die "socket: $@";
 171
 172                 my $buff = $packet->serialize();
 173                 $reply->send( $buff, 0 ) or die "Error sending: $!\n";
 174
 175 #               system("arp -s $ip $mac"),
 176
 177         } else {
 178                 print "No bootp request.\n";
 179         }
 180
 181 }