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#!/usr/bin/perl -w
#
# Copyright (C) 2008 Rien Broekstra <rien@rename-it.nl>
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; version 2 dated June,
# 1991.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
#
#
# Munin plugin to measure saturation of DHCP pools.
#
# Configuration variables:
#
# conffile - path to dhcpd's configuration file (default "/etc/dhcpd.conf")
# leasefile - path to dhcpd's leases file (default "/var/lib/dhcp/dhcpd.leases")
#
# Parameters:
#
# config (required)
#
# Version 1.0, 2-12-2008
use POSIX;
use Time::Local;
use strict;
my $CONFFILE = exists $ENV{'conffile'} ? $ENV{'conffile'} : "/etc/dhcpd.conf";
my $LEASEFILE = exists $ENV{'leasefile'} ? $ENV{'leasefile'} : "/var/lib/dhcp/dhcpd.leases";
if ( defined $ARGV[0] and $ARGV[0] eq "autoconf" ) {
}
elsif ( defined $ARGV[0] and $ARGV[0] eq "config" ) {
my (%pools, $start, $label);
# Print general information
print "graph_title DHCP pool usage (in %)\n";
print "graph_args --upper-limit 100 -l 0\n";
print "graph_vlabel %\n";
print "graph_category network\n";
# Determine the available IP pools
%pools = determine_pools();
# Print a label for each pool
foreach $start (keys %pools) {
$label = ip2string($start);
$label =~ s/\./\_/g;
print "$label.label Pool ".ip2string($start)."\n";
print "$label.warning 75\n";
print "$label.critical 100\n";
}
}
else {
my (@activeleases, %pools, $start, $end, $size, $free, $label, $lease);
# Determine all leased IP addresses
@activeleases = determine_active_leases();
# Determine the available IP pools
%pools = determine_pools();
# For each pool, count how many leases from that pool are currently active
foreach $start (keys %pools) {
$size = $pools{$start};
$end = $start+$size;
$free = $size;
foreach $lease (@activeleases) {
if ($lease >= $start && $lease <= $end) {
$free--;
}
}
$label = ip2string($start);
$label =~ s/\./\_/g;
print "$label.value ".sprintf("%.1f", 100*($size-$free)/$size)."\n";
}
}
# Parse dhcpd.conf for range statements.
#
# Returns a hash with start IP -> size
sub determine_pools {
my (%pools, @conffile, $line, $start, $end, $size);
open(CONFFILE, "<${CONFFILE}") || exit -1;
@conffile = <CONFFILE>;
close (CONFFILE);
foreach $line (@conffile) {
if ($line =~ /range[\s]+([\d]+\.[\d]+\.[\d]+\.[\d]+)[\s]+([\d]+\.[\d]+\.[\d]+\.[\d]+)/) {
$start = string2ip($1);
$end = string2ip($2);
$size = $end - $start;
defined($start) || next;
defined($end) || next;
$pools{$start} = $size;
}
}
return %pools;
}
# Very simple parser for dhcpd.leases. This will break very easily if dhcpd decides to
# format the file differently. Ideally a simple recursive-descent parser should be used.
#
# Returns an array with currently leased IP's
sub determine_active_leases {
my (@leasefile, $startdate, $enddate, $lease, @activeleases, $mytz, $line, %saw);
open(LEASEFILE, "<${LEASEFILE}") || exit -1;
@leasefile = <LEASEFILE>;
close (LEASEFILE);
@activeleases = ();
# Portable way of converting a GMT date/time string to timestamp is setting TZ to UTC, and then calling mktime()
$mytz = $ENV{'TZ'};
$ENV{'TZ'} = 'UTC 0';
tzset();
foreach $line (@leasefile) {
if ($line =~ /lease ([\d]+\.[\d]+\.[\d]+\.[\d]+)/) {
$lease = string2ip($1);
defined($lease) || next;
undef $startdate;
undef $enddate;
}
elsif ($line =~ /starts \d ([\d]{4})\/([\d]{2})\/([\d]{2}) ([\d]{2}):([\d]{2}):([\d]{2})/) {
$startdate = mktime($6, $5, $4, $3, $2-1, $1-1900, 0, 0);
}
elsif ($line =~ /ends \d ([\d]{4})\/([\d]{2})\/([\d]{2}) ([\d]{2}):([\d]{2}):([\d]{2})/) {
$enddate = mktime($6, $5, $4, $3, $2-1, $1-1900, 0, 0);
if (defined($enddate) && defined($startdate) && defined($lease)) {
if ($startdate < time() && $enddate > time()) {
push (@activeleases, $lease);
}
}
}
}
# Set TZ back to its original setting
if (defined($mytz)) {
$ENV{'TZ'} = $mytz;
}
else {
delete $ENV{'TZ'};
}
tzset();
# Sort the array, strip doubles, and return
return grep(!$saw{$_}++, @activeleases);
}
#
# Helper routine to convert an IP address a.b.c.d into an integer
#
# Returns an integer representation of an IP address
sub string2ip {
my $string = shift;
defined($string) || return undef;
if ($string =~ /([\d]+)\.([\d]+)\.([\d]+)\.([\d]+)/) {
if ($1 < 0 || $1 > 255 || $2 < 0 || $2 > 255 || $3 < 0 || $3 > 255 || $4 < 0 || $4 > 255) {
return undef;
}
else {
return $1 << 24 | $2 << 16 | $3 << 8 | $4;
}
}
return undef;
}
#
# Returns a dotted quad notation of an
#
sub ip2string {
my $ip = shift;
defined ($ip) || return undef;
return sprintf ("%d.%d.%d.%d", ($ip >> 24) & 0xff, ($ip >> 16) & 0xff, ($ip >> 8) & 0xff, $ip & 0xff);
}
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