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package Munin::Node::Configure::HostEnumeration;
use strict;
use warnings;
use Socket;
use Munin::Node::Configure::Debug;
use Exporter ();
our @ISA = qw/Exporter/;
our @EXPORT = qw/expand_hosts/;
### Network address manipulation ###############################################
# converts a hostname or IP and an optional netmask into a list of the
# hostnames and/or IPs in that network.
#
# If you haven't guessed, this is IPv4 only.
sub _hosts_in_net
{
my ($host, $mask) = @_;
my @ret;
# avoid losing the hostname that was provided. makes for more appropriate
# links in the servicedir.
#
# FIXME: this is very limited. make it work in the case when a netmask is
# provided (substitute the hostname for the corresponding IP in the list
# that is returned.
unless (defined $mask) {
return $host;
}
my $addr = _resolve($host);
die "Invalid netmask: $mask\n"
unless ($mask =~ /^\d+$/ and $mask <= 32);
my $net = unpack('N', $addr); # ntohl()
# Evil maths courtesy of nmap's TargetGroup.cc
my $low = $net & (0 - (1 << (32 - $mask)));
my $high = $net | ((1 << (32 - $mask)) - 1);
# Note that the .. operator uses signed integers. Hence the loop.
for (my $ip = $low; $ip <= $high; $ip++) {
push @ret, inet_ntoa(pack 'N', $ip);
}
return @ret;
}
# Resolves a hostname or IP, and returns the address as a bitstring in
# network byte order.
sub _resolve
{
my ($host) = @_;
my ($name, $aliases, $addrtype, $length, @addrs) = gethostbyname($host);
die "Unable to resolve $host\n" unless $name;
if (scalar @addrs > 1) {
warn sprintf "# Hostname %s resolves to %u IPs. Using %s\n",
$host,
scalar(@addrs),
inet_ntoa($addrs[0]);
}
DEBUG(sprintf "# Resolved %s to %s", $host, inet_ntoa($addrs[0]));
return $addrs[0];
}
sub expand_hosts
{
my (@unexpanded) = @_;
my @hosts;
foreach my $item (@unexpanded) {
DEBUG("Processing $item");
my ($host, $mask) = split '/', $item, 2;
push @hosts, _hosts_in_net($host, $mask);
}
return @hosts;
}
1;
__END__
=head1 NAME
Munin::Node::Configure::HostEnumeration - Takes a list of hosts, and returns
the corresponding IPs in dotted-quad form.
=head1 SYNOPSIS
@hosts = ('switch1', 'host1/24', '10.0.0.60/30');
foreach my $host (expand_hosts(@hosts)) {
# ...
}
=head1 SUBROUTINES
=over
=item B<expand_hosts>
@expanded = expand_hosts(@list);
Takes a list of hosts, and returns the corresponding IPs in dotted-quad form.
Items can be specified as a hostname or dotted-quad IP, either with or
without a netmask.
Currently only IPv4 addresses are supported.
=back
=cut
# vim: ts=4 : sw=4 : expandtab
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