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);
  14
  15 $mymac = qx/ \/sbin\/ifconfig | grep -P '^eth0.+HWaddr\\s*' | awk '{print \$5}' /;
  16 $mymac =~ tr/://d;
  17
  18 # Overrule when testing
  19 #$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                                 )
  37       || die "Socket (send) creation error: $@\n";     # yes, it uses $@ here
  38
  39 # create DHCP Packet DISCOVER
  40 $discover = Net::DHCP::Packet->new(
  41                           Chaddr => $mymac,
  42                           Giaddr => $send->sockhost(),
  43               Xid => int(rand(0xFFFFFFFF)), # random xid
  44               DHO_DHCP_MESSAGE_TYPE() => DHCPDISCOVER(),
  45               Flags => 0x8000,
  46                           DHO_VENDOR_CLASS_IDENTIFIER() => 'foo',
  47               );
  48
  49 logger("Sending DISCOVER to " . $send->peerhost . ":" . $send->peerport);
  50 logger($discover->toString());
  51 $send->send($discover->serialize(), 0)
  52               or die "Error sending:$!\n";
  53
  54 $receive = IO::Socket::IP->new(  Proto => 'udp',
  55                                 Broadcast => 1,
  56                                 LocalPort => 'bootpc(68)',
  57                                 #LocalAddr => inet_ntoa(INADDR_LOOPBACK),#(INADDR_ANY),
  58                                 )
  59       || die "Socket (receive) creation error: $@\n";     # yes, it uses $@ here
  60
  61 logger("Listen: " . $receive->sockhost . ":" . $receive->sockport);
  62 logger("Waiting for response from server");
  63 $receive->recv($buf, 1024, 0);
  64 logger("Got response from " . $receive->peerhost . ":" . $receive->peerport);
  65 $receive->close;
  66 $response = new Net::DHCP::Packet($buf);
  67 $serverip = $response->getOptionValue(DHO_DHCP_SERVER_IDENTIFIER());
  68 $myip = $response->yiaddr();
  69
  70 logger($response->toString());
  71
  72 # create DHCP Packet REQUEST
  73 $request = Net::DHCP::Packet->new(
  74                       Xid => int(rand(0xFFFFFFFF)), # random xid
  75                       Chaddr => $mymac,
  76                       Giaddr => $send->sockhost(),
  77                       DHO_DHCP_MESSAGE_TYPE() => DHCPREQUEST(),
  78                                           DHO_VENDOR_CLASS_IDENTIFIER() => 'foo',
  79                       DHO_DHCP_REQUESTED_ADDRESS() => $myip,
  80                       );
  81
  82 logger("Sending REQUEST to " . $send->peerhost . ":" . $send->peerport);
  83 logger($request->toString());
  84
  85 $send->send($request->serialize())
  86               or die "Error sending:$!\n";
  87 $send->close;
  88
  89 $receive = IO::Socket::IP->new(  Proto => 'udp',
  90                                 Broadcast => 1,
  91                                 LocalPort => 'bootpc(68)',
  92                                 #LocalAddr => inet_ntoa(INADDR_LOOPBACK),#inet_ntoa(INADDR_ANY),
  93                                 )
  94       || die "Socket creation error: $@\n";     # yes, it uses $@ here
  95
  96 logger("Waiting for response from server");
  97 $receive->recv($buf, 1024, 0);
  98 logger("Got response from " . $receive->peerhost . ":" . $receive->peerport);
  99 $receive->close;
 100 $response = new Net::DHCP::Packet($buf);
 101 logger($response->toString());
 102
 103 if ($response->getOptionValue(DHO_DHCP_MESSAGE_TYPE()) == DHCPACK()) {
 104         $send = IO::Socket::IP->new(  Proto => 'udp',
 105                                                                   Broadcast => 1,
 106                                                                   PeerPort => 'bootps(67)',
 107                                                                   PeerAddr => $serverip,
 108                                                                 )
 109                   || die "Socket (send) creation error: $@\n";     # yes, it uses $@ here
 110
 111         # create DHCP Packet REQUEST
 112         $request = Net::DHCP::Packet->new(
 113                                                   op => BOOTREQUEST(),
 114                                                   Xid => int(rand(0xFFFFFFFF)), # random xid
 115                                                   Chaddr => $mymac,
 116                                                   Ciaddr => $myip,
 117                                                   Giaddr => $send->sockhost(),
 118                                                   DHO_VENDOR_CLASS_IDENTIFIER() => 'foo',
 119                                                   DHO_DHCP_MESSAGE_TYPE() => DHCPRELEASE()
 120                                                   );
 121
 122         logger("Sending REQUEST to " . $send->peerhost . ":" . $send->peerport);
 123         logger($request->toString());
 124
 125         $send->send($request->serialize())
 126                                   or die "Error sending:$!\n";
 127         $send->close;
 128 } else {
 129         logger("Request for ip $myip was denied")
 130 }