/[pxelator]/bin/dhcpd.pl
This is repository of my old source code which isn't updated any more. Go to git.rot13.org for current projects!
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Contents of /bin/dhcpd.pl

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Revision 22 - (show annotations)
Tue Jul 28 16:35:49 2009 UTC (10 years ago) by dpavlin
File MIME type: text/plain
File size: 3186 byte(s)
- correct handling of files and symlinks in conf/
- use autodie for errors
- move detection of server IP into dhcpd
- $gpxe_file defines payload for gPXE

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 Net::DHCP::Packet;
12 use Net::DHCP::Constants;
13 use File::Slurp;
14 use Data::Dump qw/dump/;
15
16 die "need to run $0 as root like this\nsudo $0\n" unless $< == 0;
17
18 my $debug = shift @ARGV;
19
20 our ( $file, $gpxe_file );
21 our ( $ip_from, $ip_to ) = ( 10, 100 );
22
23 our $server_ip = readlink 'conf/server.ip' if -l 'conf/server.ip';
24
25 if ( ! $server_ip ) {
26 $server_ip = `/sbin/ifconfig`;
27 $server_ip =~ s/^.+?addr:([\d\.]+).*$/$1/gs;
28 warn "auto-configure server ip to $server_ip\n";
29 } else {
30 warn "server ip $server_ip\n";
31 }
32
33 my $sock = IO::Socket::INET->new(
34 LocalPort => 67,
35 # LocalAddr => 'localhost',
36 # LocalAddr => '10.0.0.100',
37 LocalAddr => '0.0.0.0',
38 Proto => 'udp',
39 ReuseAddr => 1,
40 # PeerPort => getservbyname('bootpc', 'udp'),
41 Broadcast => 1,
42 Type => SOCK_DGRAM,
43 ) or die "Failed to bind to socket: $@";
44
45
46 my $addr = $ip_from;
47
48 sub client_ip {
49 my ( $mac ) = @_;
50
51 my $conf = "conf/$server_ip";
52 mkdir $conf unless -e $conf;
53
54 if ( -e "$conf/mac/$mac" ) {
55 my $ip = read_file "$conf/mac/$mac";
56 print "$mac old $ip\n";
57 return $ip;
58 }
59
60 mkdir $_ foreach grep { ! -e $_ } map { "$conf/$_" } ( 'ip', 'mac' );
61
62 my $prefix = $server_ip;
63 $prefix =~ s{\.\d+$}{.};
64 my $ip = $prefix . $addr;
65 while ( -e "conf/ip/$ip" ) {
66 $ip = $prefix . $addr++;
67 die "all addresses allocated!" if $addr == $ip_to;
68 }
69
70 write_file "$conf/mac/$mac", $ip;
71 unlink "$conf/ip/$ip" if -e "$conf/ip/$ip";
72 symlink "$conf/mac/$mac", "$conf/ip/$ip";
73
74 print "$mac NEW $ip\n";
75
76 return $ip;
77 }
78
79 while (1) {
80
81 require "config.pl"; # refresh config
82
83 print "waiting for DHCP requests on ",$sock->sockhost,":",$sock->sockport,"\n";
84
85 my $buf;
86 $sock->recv($buf, 1024);
87 print "<< ",$sock->peerhost,":",$sock->peerport,"\n";
88
89 if (defined $buf) {
90
91 my $dhcp;
92
93 eval { $dhcp = Net::DHCP::Packet->new($buf); };
94 die "can't use request", dump( $buf ) if $@;
95
96 if ( $debug ) {
97 warn "recv: ", $dhcp->toString, "\n\n";
98 }
99
100 my $mac = substr($dhcp->chaddr(),0,$dhcp->hlen()*2);
101 my $ip = client_ip($mac);
102 my $user_class = $dhcp->getOptionValue(DHO_USER_CLASS());
103
104 if ( $user_class eq 'gPXE' ) {
105 $file = $gpxe_file;
106 } elsif ( ! $file ) {
107 $file = 'undionly.kpxe';
108 }
109
110 my $packet = new Net::DHCP::Packet(
111 Op => BOOTREPLY(),
112 Hops => $dhcp->hops(),
113 Xid => $dhcp->xid(),
114 Flags => $dhcp->flags(),
115 Ciaddr => $dhcp->ciaddr(),
116 Yiaddr => $ip,
117 Siaddr => $server_ip,
118 Giaddr => $dhcp->giaddr(),
119 Chaddr => $dhcp->chaddr(),
120 File => $file,
121 # DHO_DHCP_MESSAGE_TYPE() => DHCPACK(),
122 DHO_SUBNET_MASK() => '255.0.0.0',
123 );
124
125 warn ">> $mac == $ip server: $server_ip file: $file\n";
126
127 warn "## ",$packet->toString(),"\n" if $debug;
128
129 my $reply = IO::Socket::INET->new(
130 LocalAddr => $server_ip,
131 LocalPort => 67,
132 Proto => "udp",
133 Broadcast => 1,
134 PeerAddr => '255.255.255.255',
135 PeerPort => 68,
136 Reuse => 1,
137 ) or die "socket: $@";
138
139 my $buff = $packet->serialize();
140 $reply->send( $buff, 0 ) or die "Error sending: $!\n";
141
142 # system("arp -s $ip $mac"),
143
144 } else {
145 print "No bootp request.\n";
146 }
147
148 }

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