dhcp.pl

   1 #!/usr/bin/perl
   2 # Simple DHCP client - sending a broadcasted DHCP Discover request
   3
   4 use strict;
   5 use warnings;
   6 use IO::Socket::IP -register;
   7
   8 use Net::DHCP::Packet;
   9 use Net::DHCP::Constants;
  10
  11 use POSIX qw(setsid strftime);
  12
  13 my ($request, $send, $receive, $discover, $response, $buf, $serverip, $myip, $mymac, $hostname);
  14
  15 $mymac = qx/ \/sbin\/ifconfig | grep -P '^eth0.+HWaddr\\s*' | awk '{print \$5}' /;
  16 $mymac =~ tr/://d;
  17 chomp($hostname = `hostname -s`);
  18 # Overrule when testing
  19 #$mymac = '001cc0c33317';
  20 logger("mac: $mymac");
  21
  22 # sample logger
  23 sub logger{
  24     my $str = shift;
  25     print STDOUT strftime "[%d/%b/%Y:%H:%M:%S] ", localtime;
  26     print STDOUT "$str\n";
  27 }
  28
  29 logger("DHCPd tester - dummy client");
  30
  31 logger("Opening socket");
  32 $send = IO::Socket::IP->new(  Proto => 'udp',
  33                                 Broadcast => 1,
  34                                 PeerPort => 'bootps(67)',
  35                                 PeerAddr => inet_ntoa(INADDR_LOOPBACK),#(INADDR_BROADCAST),
  36                                 #PeerAddr => inet_ntoa(INADDR_BROADCAST),
  37                                 )
  38       || die "Socket (send) creation error: $@\n";     # yes, it uses $@ here
  39
  40 # create DHCP Packet DISCOVER
  41 $discover = Net::DHCP::Packet->new(
  42                           Chaddr => $mymac,
  43                           Giaddr => $send->sockhost(),
  44               Xid => int(rand(0xFFFFFFFF)), # random xid
  45               DHO_DHCP_MESSAGE_TYPE() => DHCPDISCOVER(),
  46               Flags => 0x8000,
  47                           DHO_VENDOR_CLASS_IDENTIFIER() => 'foo',
  48                           DHO_HOST_NAME() => $hostname,
  49               );
  50
  51 logger("Sending DISCOVER to " . $send->peerhost . ":" . $send->peerport);
  52 logger($discover->toString());
  53 $send->send($discover->serialize(), 0)
  54               or die "Error sending:$!\n";
  55
  56 $receive = IO::Socket::IP->new(  Proto => 'udp',
  57                                 Broadcast => 1,
  58                                 LocalPort => 'bootpc(68)',
  59                                 #LocalAddr => inet_ntoa(INADDR_LOOPBACK),#(INADDR_ANY),
  60                                 LocalAddr => inet_ntoa(INADDR_ANY),
  61                                 )
  62       || die "Socket (receive) creation error: $@\n";     # yes, it uses $@ here
  63
  64 logger("Listen: " . $receive->sockhost . ":" . $receive->sockport);
  65 logger("Waiting for response from server");
  66 $receive->recv($buf, 1024, 0);
  67 logger("Got response from " . $receive->peerhost . ":" . $receive->peerport);
  68 $receive->close;
  69 $response = new Net::DHCP::Packet($buf);
  70 if ($response->getOptionValue(DHO_DHCP_MESSAGE_TYPE()) == DHCPNAK()) {
  71         logger("Request for ip was denied");
  72         exit;
  73 }
  74 $serverip = $response->getOptionValue(DHO_DHCP_SERVER_IDENTIFIER());
  75 $myip = $response->yiaddr();
  76
  77 logger($response->toString());
  78
  79 # create DHCP Packet REQUEST
  80 $request = Net::DHCP::Packet->new(
  81                       Xid => int(rand(0xFFFFFFFF)), # random xid
  82                       Chaddr => $mymac,
  83                       Giaddr => $send->sockhost(),
  84                       DHO_DHCP_MESSAGE_TYPE() => DHCPREQUEST(),
  85                                           DHO_VENDOR_CLASS_IDENTIFIER() => 'foo',
  86                                           DHO_HOST_NAME() => $hostname,
  87                       DHO_DHCP_REQUESTED_ADDRESS() => $myip,
  88                       );
  89
  90 logger("Sending REQUEST to " . $send->peerhost . ":" . $send->peerport);
  91 logger($request->toString());
  92
  93 $send->send($request->serialize())
  94               or die "Error sending:$!\n";
  95 $send->close;
  96
  97 $receive = IO::Socket::IP->new(  Proto => 'udp',
  98                                 Broadcast => 1,
  99                                 LocalPort => 'bootpc(68)',
 100                                 #LocalAddr => inet_ntoa(INADDR_LOOPBACK),#inet_ntoa(INADDR_ANY),
 101                                 LocalAddr => inet_ntoa(INADDR_ANY),
 102                                 )
 103       || die "Socket creation error: $@\n";     # yes, it uses $@ here
 104
 105 logger("Waiting for response from server");
 106 $receive->recv($buf, 1024, 0);
 107 logger("Got response from " . $receive->peerhost . ":" . $receive->peerport);
 108 $receive->close;
 109 $response = new Net::DHCP::Packet($buf);
 110 logger($response->toString());
 111
 112 if ($response->getOptionValue(DHO_DHCP_MESSAGE_TYPE()) == DHCPACK()) {
 113         $send = IO::Socket::IP->new(  Proto => 'udp',
 114                                                                   Broadcast => 1,
 115                                                                   PeerPort => 'bootps(67)',
 116                                                                   PeerAddr => $serverip,
 117                                                                 )
 118                   || die "Socket (send) creation error: $@\n";     # yes, it uses $@ here
 119
 120         # create DHCP Packet REQUEST
 121         $request = Net::DHCP::Packet->new(
 122                                                   op => BOOTREQUEST(),
 123                                                   Xid => int(rand(0xFFFFFFFF)), # random xid
 124                                                   Chaddr => $mymac,
 125                                                   Ciaddr => $myip,
 126                                                   Giaddr => $send->sockhost(),
 127                                                   DHO_VENDOR_CLASS_IDENTIFIER() => 'foo',
 128                                                   DHO_HOST_NAME() => $hostname,
 129                                                   DHO_DHCP_MESSAGE_TYPE() => DHCPRELEASE()
 130                                                   );
 131
 132         logger("Sending REQUEST to " . $send->peerhost . ":" . $send->peerport);
 133         logger($request->toString());
 134
 135         $send->send($request->serialize())
 136                                   or die "Error sending:$!\n";
 137         $send->close;
 138 } else {
 139         logger("Request for ip $myip was denied")
 140 }