#!/usr/bin/perl -w

# Plugin to monitor offsets to multiple NTP peers.
# NB currently only works for IPv4 peers
#
# (c)2008 Chris Hastie: chris (at) oak (hyphen) wood (dot) co (dot) uk
#
# Parameters understood:
#
# 	config   (required)
# 	autoconf (optional - used by munin-node-configure)
#
# Config variables:
#
#       ntpq            - path to ntpq program
#
# 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, either version 3 of the License, or
# (at your option) any later version.
#
# 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, see <http://www.gnu.org/licenses/>.
#
# Change log
# v1.0.0    2008-07-21        Chris Hastie
# initial release
# v1.0.1    2009-06-05	      Tony Hoyle
# ipv6 support.  Remove dns lookups.
#
#
# Magic markers - optional - used by installation scripts and
# munin-node-configure:
#
#%# family=contrib
#%# capabilities=autoconf
#

use strict;

my $NTPQ = $ENV{ntpq} || "ntpq";
my $COMMAND    =      "$NTPQ -nc associations";

my $statedir = $ENV{statedir} || $ENV{MUNIN_PLUGSTATE};
my $statefile = "$statedir/ntp_peers.state";

# autoconf
if ($ARGV[0] and $ARGV[0] eq "autoconf") {
	`$NTPQ -c help >/dev/null 2>/dev/null`;
	if ($? eq "0") {
		if (`$NTPQ -np | wc -l` > 0) {
			print "yes\n";
		} else {
			print "no (unable to list peers)\n";
		}
	} else {
		print "no (ntpq not found)\n";
	}
	exit 0;
}

my %peers;

# get data from ntpq
open(SERVICE, "$COMMAND |")
  or die("Could not execute '$COMMAND': $!");

while (<SERVICE>) {
    if(/^\s*\d+\s+(\d+)\s+/) {
      my ($name, $offset) = &lookupip($1);
      $peers{$name} = $offset;
    }
}
close(SERVICE);

# config
if ($ARGV[0] and $ARGV[0] eq 'config') {
  print "graph_title NTP peer offsets\n";
  print "graph_args --base 1000\n";
  print "graph_vlabel ms\n";
  print "graph_category time\n";
  print "graph_info Offset (in ms) to the server's NTP peers\n";
  print "graph_order ";
  foreach my $key (sort keys %peers) {
    print &sanitize_field($key) . " ";
  }
  print "\n";
  foreach my $peer (keys %peers) {
    print &sanitize_field($peer) . ".label " . $peer . "\n";
  }
  exit 0;
}

# send output
foreach my $peer (keys %peers) {
  print &sanitize_field($peer) . ".value " . &getpeeroffset($peer) . "\n";
}

# create a valid munin field name from the hostname
sub sanitize_field () {
  my $field = shift;

  # replace illegal characters with an underscore
  $field =~ s/[^A-Za-z0-9_]/_/g;
  # prepend an underscore if name starts with a number
  $field =~ s/^([^A-Za-z_])/_$1/;

  # truncate to 19 characters
  if (length($field) > 19) {
    $field = substr($field, 0, 19);
  }
  return $field
}

# get an IP address from the underscore escaped
# value of env.hostname_<key>
sub desanitize_field () {
  my $field = shift;
  $field =~ s/_/\./g;
  return $field
}

# Get name, offset info for peers
# It would be more efficient to use mrv here to avoid rerunning ntpq
sub lookupip() {
  my $assocID = shift;
  my $CMD = "$NTPQ -c \"rv $assocID srcadr,offset\"";
  my $addr="";
  my $offset="";

  # get data from ntpq
  open(SERVICE2, "$CMD |")
     or die("Could not execute '$CMD': $!");

  while(<SERVICE2>) {
    if(/^srcadr=([^\s]+),\soffset=(.+)$/) {
      $addr = $1;
      $offset = $2;
    }
  }
  close(SERVICE2);
  return ($addr, $offset);
}

# returns the offset, or U if it is undefined
sub getpeeroffset() {
  my $name = shift;
  my $rtn = 'U';
  if (exists($peers{$name})) {
    $rtn = $peers{$name};
  }
  return $rtn
}

=pod

=head1 Description

ntp_peers - A munin plugin to monitor offsets to multiple NTP peers and
graph them on a single graph

=head1 Parameters understood:

  config   (required)
  autoconf (optional - used by munin-node-configure)

=head1 Configuration variables:

All configuration parameters are optional

  ntpq            - path to ntpq program
  statedir        - directory in which to place state file
  hostname_<key>  - override hostname for peer <key>. <key> is
                    an IPv4 address with dots replaced by underscores.
                    Useful for reference clocks, eg
                    env.hostname_127_127_43_0  .GPS.

=head1 Known issues

ntp_peers will not monitor IPv6 peers

=cut