#!/usr/bin/perl
# © 2001 Ronald Florence <ron@18james.com>
# last modified ron@rosie.18james.com, 14 Jun 2002

use Socket;
my %d;
my $conf = "/etc/ntp.conf";
my $ntpq = "/usr/bin/ntpq";

if ($#ARGV == 1)
  {
    for (@ARGV) 
      {
	$_ = join ".", unpack('C4', (gethostbyname $_)[4]) if /[a-zA-Z]/;
	$d{$_} = 0;
      }
  }
elsif (open (NTPCONF, $conf))
  {
    while (<NTPCONF>) 
      {
	if (/^server/) 
	  {
	    ($s, $server) = split;
	    $ip = ($server =~ /[A-Za-z]/) ?
	      join ".", unpack('C4', (gethostbyname $server)[4]) : $server; 
	    $d{$ip} = 0;
	    last if keys(%d) == 2;
	  }
      }
  }
else { die "usage: $0 [ntp-server-1 ntp-server-2]\n" ; }

foreach (`$ntpq -pn`) 
  {
    ($remote,$ref,$st,$t,$w,$p,$reach,$delay,$o,$d) = split;
    for (keys %d) 
      {
	$d{$_} = $delay*1000 if $remote =~ /$_/ && $reach > 0 && $delay > 0;
      }
    if ($remote =~ /^\*/) 
      { 
	$peer = substr $remote, 1;
	$id = $ref; 
	$stratum = $st;
      }
  }

foreach ($peer, $id) 
  {
    if (/[a-zA-Z]/) { s/^\.|\.$//g; }
    else { $_ = gethostbyaddr pack('C4', split /\./, $_), AF_INET || $_; } 
  }

if ($#ARGV == 1)  { print map "$d{$_}\n", @ARGV; }
else  { print map "$_\n", values %d; }
print "stratum $stratum\n",
      "$peer ($id)\n";

__END__

=head1 NAME

    delay.pl - charts and logs network delays for mrtg

=head1 SYNOPSIS

  Requires a working NTP installation.

  Use some variation of the following in the mrtg.cfg file:

     Target[delay]: `./delay.pl ntp-server1 ntp-server2`
     Options[delay]: growright, gauge, nopercent
     MaxBytes[delay]: 500000
     Title[delay]: Network Delay
     PageTop[delay]: <h3>NTP Network Delay</h3>
     kMG[delay]: µ,m,,
     YLegend[delay]: delay (ms)
     ShortLegend[delay]: sec
     LegendI[delay]: NTP-1:
     LegendO[delay]: NTP-2:
     Legend1[delay]: NTP network delay to <b>ntp-server-1</b>
     Legend2[delay]: NTP network delay to <b>ntp-server-2</b>

  If the first two servers in your /etc/inet/ntp.conf file are the
  servers you want to use to measure delays, you don't need to specify
  the servers on the command line.

=head1 DESCRIPTION

    A simple perl script to read and log the delays from the ntpq -p
    command on a system running NTP, and massage the data into a
    format suitable for mrtg.  Outputs delays from two NTP-servers in
    µsec, and the stratum, server and refid of the server with which
    the local clocks are synced -- in mrtg format.

=head1 LICENSE

    You may distribute this script under the same license as Perl itself.

=head1 AUTHOR

    Ronald Florence <ron@18james.com> 

=cut