Munin contributed plugins

#!/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-1;

	$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) {

	next if $line =~ /^\s*#/;

	if ($line =~ /range[\s]+([\d]+\.[\d]+\.[\d]+\.[\d]+)[\s]+([\d]+\.[\d]+\.[\d]+\.[\d]+)/) {

	    $start = string2ip($1);

	    $end = string2ip($2);

	    defined($start) || next;

	    defined($end) || next;

            # The range statement gives the lowest and highest IP addresses in a range.

	    $size = $end - $start + 1;

	    $pools{$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);

}