contrib/dnslist/dnslist.pl

#!/usr/bin/perl

# dnslist - Read state file from dnsmasq and create a nice web page to display
#           a list of DHCP clients.
# 
# Copyright (C) 2004  Thomas Tuttle
# 
# 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 2 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
# MERCHANTIBILITY 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
# 
# * The license is in fact included at the end of this file, and can
#   either be viewed by reading everything after "__DATA__" or by
#   running dnslist with the '-l' option.
# 
# Version: 0.2
# Author:  Thomas Tuttle
# Email:   dnslist.20.thinkinginbinary@spamgourmet.org
# License: GNU General Public License, version 2.0
#
# v. 0.0: Too ugly to publish, thrown out.
#
# v. 0.1: First rewrite.
#         Added master host list so offline hosts can still be displayed.
#         Fixed modification detection (a newer modification time is lower.)
#
# v. 0.2: Fixed Client ID = "*" => "None"
#         Fixed HTML entities (a client ID of ????<? screwed it up)
#         Fixed command-line argument processing (apparently, "shift @ARGV" !=
#             "$_ = shift @ARGV"...)
#         Added license information.

use Template;

# Location of state file.  (This is the dnsmasq default.)
# Change with -s <file>
my $dnsmasq_state_file = '/var/lib/misc/dnsmasq.leases';
# Location of template.  (Assumed to be in current directory.)
# Change with -t <file>
my $html_template_file = 'dnslist.tt2';
# File to write HTML page to.  (This is where Slackware puts WWW pages.  It may
# be different on other systems.  Make sure the permissions are set correctly
# for it.)
my $html_output_file = '/var/www/htdocs/dhcp.html';
# Time to wait after each page update.  (The state file is checked for changes
# before each update but is not read in each time, in case it is very big.  The
# page is rewritten just so the "(updated __/__ __:__:__)" text changes ;-)
my $wait_time = 2;

# Read command-line arguments.
while ($_ = shift @ARGV) {
	if (/-s/) { $dnsmasq_state_file = shift; next; }
	if (/-t/) { $html_template_file = shift; next; }
	if (/-o/) { $html_output_file = shift;   next; }
	if (/-d/) { $wait_time = shift;          next; }
	if (/-l/) { show_license();              exit; }
	die "usage: dnslist [-s state_file] [-t template_file] [-o output_file] [-d delay_time]\n";
}

# Master list of clients, offline and online.
my $list = {};
# Sorted host list.  (It's actually sorted by IP--the sub &byip() compares two
# IP addresses, octet by octet, and figures out which is higher.)
my @hosts = ();
# Last time the state file was changed.
my $last_state_change;

# Check for a change to the state file.
sub check_state {
	if (defined $last_state_change) {
		if (-M $dnsmasq_state_file < $last_state_change) {
			print "check_state: state file has been changed.\n";
			$last_state_change = -M $dnsmasq_state_file;
			return 1;
		} else {
			return 0;
		}
	} else {
		# Last change undefined, so we are running for the first time.
		print "check_state: reading state file at startup.\n";
		read_state();
		$last_state_change = -M $dnsmasq_state_file;
		return 1;
	}
}

# Read data in state file.
sub read_state {
	my $old;
	my $new;
	# Open file.
	unless (open STATE, $dnsmasq_state_file) {
		warn "read_state: can't open $dnsmasq_state_file!\n";
		return 0;
	}
	# Mark all hosts as offline, saving old state.
	foreach $ether (keys %{$list}) {
		$list->{$ether}->{'old_online'} = $list->{$ether}->{'online'};
		$list->{$ether}->{'online'} = 0;
	}
	# Read hosts.
	while (<STATE>) {
		chomp;
		@host{qw/raw_lease ether_addr ip_addr hostname raw_client_id/} = split /\s+/;
		$ether = $host{ether_addr};
		# Mark each online host as online.
		$list->{$ether}->{'online'} = 1;
		# Copy data to master list.
		foreach $key (keys %host) {
			$list->{$ether}->{$key} = $host{$key};
		}
	}
	close STATE;
	# Handle changes in offline/online state.  (The sub &do_host() handles
	# all of the extra stuff to do with a host's data once it is read.
	foreach $ether (keys %{$list}) {
		$old = $list->{$ether}->{'old_online'};
		$new = $list->{$ether}->{'online'};
		if (not $old) {
			if (not $new) {
				do_host($ether, 'offline');
			} else {
				do_host($ether, 'join');
			}
		} else {
			if (not $new) {
				do_host($ether, 'leave');
			} else {
				do_host($ether, 'online');
			}
		}
	}
	# Sort hosts by IP ;-)
	@hosts = sort byip values %{$list};
	# Copy sorted list to template data store.
	$data->{'hosts'} = [ @hosts ];
}

# Do stuff per host.
sub do_host {
	my ($ether, $status) = @_;
	
	# Find textual representation of DHCP client ID.
	if ($list->{$ether}->{'raw_client_id'} eq '*') {
		$list->{$ether}->{'text_client_id'} = 'None';
	} else {
		my $text = "";
		foreach $char (split /:/, $list->{$ether}->{'raw_client_id'}) {
			$char = pack('H2', $char);
			if (ord($char) >= 32 and ord($char) <= 127) {
				$text .= $char;
			} else {
				$text .= "?";
			}
		}
		$list->{$ether}->{'text_client_id'} = $text;
	}
		
	# Convert lease expiration date/time to text.
	if ($list->{$ether}->{'raw_lease'} == 0) {
		$list->{$ether}->{'text_lease'} = 'Never';
	} else {
		$list->{$ether}->{'text_lease'} = nice_time($list->{$ether}->{'raw_lease'});
	}
	
	if ($status eq 'offline') {
		# Nothing to do.
	} elsif ($status eq 'online') {
		# Nothing to do.
	} elsif ($status eq 'join') {
		# Update times for joining host.
		print "do_host: $ether joined the network.\n";
		$list->{$ether}->{'join_time'} = time;
		$list->{$ether}->{'since'} = nice_time(time);
	} elsif ($status eq 'leave') {
		# Update times for leaving host.
		print "do_host: $ether left the network.\n";
		$list->{$ether}->{'leave_time'} = time;
		$list->{$ether}->{'since'} = nice_time(time);
	}
	
}

# Convert time to a string representation.
sub nice_time {
	my $time = shift;
	my ($sec, $min, $hour, $mday, $mon, $year, $wday, $yday, $dst) = localtime($time);
	$sec = pad($sec, '0', 2);
	$min = pad($min, '0', 2);
	$hour = pad($hour, '0', 2);
	$mon = pad($mon, '0', 2);
	$mday = pad($mday, '0', 2);
	return "$mon/$mday $hour:$min:$sec";
}

# Pad string to a certain length by repeatedly prepending another string.
sub pad {
	my ($text, $pad, $length) = @_;
	while (length($text) < $length) {
		$text = "$pad$text";
	}
	return $text;
}

# Compare two IP addresses.  (Uses $a and $b from sort.)
sub byip {
	# Split into octets.
	my @a = split /\./, $a->{ip_addr};
	my @b = split /\./, $b->{ip_addr};
	# Compare octets.
	foreach $n (0..3) {
		return $a[$n] <=> $b[$n] if ($a[$n] != $b[$n]);
	}
	# If we get here there is no difference.
	return 0;
}
		
# Output HTML file.
sub write_output {
	# Create new template object.
	my $template = Template->new(
		{
			ABSOLUTE => 1, # /var/www/... is an absolute path
			OUTPUT => $html_output_file # put it here, not STDOUT
		}
	);
	$data->{'updated'} = nice_time(time); # add "(updated ...)" to file
	unless ($template->process($html_template_file, $data)) { # do it
		warn "write_output: Template Toolkit error: " . $template->error() . "\n";
		return 0;
	}
	print "write_output: page updated.\n";
	return 1;
}

sub show_license {
	while (<DATA>) {
		print;
		$line++;
		if ($line == 24) { <>; $line = 1; }
	}
}

# Main loop.
while (1) {
	# Check for state change.
	if (check_state()) {
		read_state();
		sleep 1; # Sleep for a second just so we don't wear anything
		         # out.  (By not sleeping the whole time after a change
			 # we can detect rapid changes more easily--like if 300
			 # hosts all come back online, they show up quicker.)
	} else {
		sleep $wait_time; # Take a nap.
	}
	write_output(); # Write the file anyway.
}
__DATA__
		    GNU GENERAL PUBLIC LICENSE
		       Version 2, June 1991

 Copyright (C) 1989, 1991 Free Software Foundation, Inc.
                       59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 Everyone is permitted to copy and distribute verbatim copies
 of this license document, but changing it is not allowed.

			    Preamble

  The licenses for most software are designed to take away your
freedom to share and change it.  By contrast, the GNU General Public
License is intended to guarantee your freedom to share and change free
software--to make sure the software is free for all its users.  This
General Public License applies to most of the Free Software
Foundation's software and to any other program whose authors commit to
using it.  (Some other Free Software Foundation software is covered by
the GNU Library General Public License instead.)  You can apply it to
your programs, too.

  When we speak of free software, we are referring to freedom, not
price.  Our General Public Licenses are designed to make sure that you
have the freedom to distribute copies of free software (and charge for
this service if you wish), that you receive source code or can get it
if you want it, that you can change the software or use pieces of it
in new free programs; and that you know you can do these things.

  To protect your rights, we need to make restrictions that forbid
anyone to deny you these rights or to ask you to surrender the rights.
These restrictions translate to certain responsibilities for you if you
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  For example, if you distribute copies of such a program, whether
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you have.  You must make sure that they, too, receive or can get the
source code.  And you must show them these terms so they know their
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  We protect your rights with two steps: (1) copyright the software, and
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  Finally, any free program is threatened constantly by software
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  The precise terms and conditions for copying, distribution and
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		    GNU GENERAL PUBLIC LICENSE
   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION

  0. This License applies to any program or other work which contains
a notice placed by the copyright holder saying it may be distributed
under the terms of this General Public License.  The "Program", below,
refers to any such program or work, and a "work based on the Program"
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the term "modification".)  Each licensee is addressed as "you".

Activities other than copying, distribution and modification are not
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running the Program is not restricted, and the output from the Program
is covered only if its contents constitute a work based on the
Program (independent of having been made by running the Program).
Whether that is true depends on what the Program does.

  1. You may copy and distribute verbatim copies of the Program's
source code as you receive it, in any medium, provided that you
conspicuously and appropriately publish on each copy an appropriate
copyright notice and disclaimer of warranty; keep intact all the
notices that refer to this License and to the absence of any warranty;
and give any other recipients of the Program a copy of this License
along with the Program.

You may charge a fee for the physical act of transferring a copy, and
you may at your option offer warranty protection in exchange for a fee.

  2. You may modify your copy or copies of the Program or any portion
of it, thus forming a work based on the Program, and copy and
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above, provided that you also meet all of these conditions:

    a) You must cause the modified files to carry prominent notices
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    b) You must cause any work that you distribute or publish, that in
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    c) If the modified program normally reads commands interactively
    when run, you must cause it, when started running for such
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    announcement including an appropriate copyright notice and a
    notice that there is no warranty (or else, saying that you provide
    a warranty) and that users may redistribute the program under
    these conditions, and telling the user how to view a copy of this
    License.  (Exception: if the Program itself is interactive but
    does not normally print such an announcement, your work based on
    the Program is not required to print an announcement.)

These requirements apply to the modified work as a whole.  If
identifiable sections of that work are not derived from the Program,
and can be reasonably considered independent and separate works in
themselves, then this License, and its terms, do not apply to those
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distribute the same sections as part of a whole which is a work based
on the Program, the distribution of the whole must be on the terms of
this License, whose permissions for other licensees extend to the
entire whole, and thus to each and every part regardless of who wrote it.

Thus, it is not the intent of this section to claim rights or contest
your rights to work written entirely by you; rather, the intent is to
exercise the right to control the distribution of derivative or
collective works based on the Program.

In addition, mere aggregation of another work not based on the Program
with the Program (or with a work based on the Program) on a volume of
a storage or distribution medium does not bring the other work under
the scope of this License.

  3. You may copy and distribute the Program (or a work based on it,
under Section 2) in object code or executable form under the terms of
Sections 1 and 2 above provided that you also do one of the following:

    a) Accompany it with the complete corresponding machine-readable
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    customarily used for software interchange; or,

    c) Accompany it with the information you received as to the offer
    to distribute corresponding source code.  (This alternative is
    allowed only for noncommercial distribution and only if you
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The source code for a work means the preferred form of the work for
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distribution of the source code, even though third parties are not
compelled to copy the source along with the object code.

  4. You may not copy, modify, sublicense, or distribute the Program
except as expressly provided under this License.  Any attempt
otherwise to copy, modify, sublicense or distribute the Program is
void, and will automatically terminate your rights under this License.
However, parties who have received copies, or rights, from you under
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  5. You are not required to accept this License, since you have not
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may not distribute the Program at all.  For example, if a patent
license would not permit royalty-free redistribution of the Program by
all those who receive copies directly or indirectly through you, then
the only way you could satisfy both it and this License would be to
refrain entirely from distribution of the Program.

If any portion of this section is held invalid or unenforceable under
any particular circumstance, the balance of the section is intended to
apply and the section as a whole is intended to apply in other
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It is not the purpose of this section to induce you to infringe any
patents or other property right claims or to contest validity of any
such claims; this section has the sole purpose of protecting the
integrity of the free software distribution system, which is
implemented by public license practices.  Many people have made
generous contributions to the wide range of software distributed
through that system in reliance on consistent application of that
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to distribute software through any other system and a licensee cannot
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This section is intended to make thoroughly clear what is believed to
be a consequence of the rest of this License.

  8. If the distribution and/or use of the Program is restricted in
certain countries either by patents or by copyrighted interfaces, the
original copyright holder who places the Program under this License
may add an explicit geographical distribution limitation excluding
those countries, so that distribution is permitted only in or among
countries not thus excluded.  In such case, this License incorporates
the limitation as if written in the body of this License.

  9. The Free Software Foundation may publish revised and/or new versions
of the General Public License from time to time.  Such new versions will
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address new problems or concerns.

Each version is given a distinguishing version number.  If the Program
specifies a version number of this License which applies to it and "any
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Foundation.

  10. If you wish to incorporate parts of the Program into other free
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			    NO WARRANTY

  11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.  EXCEPT WHEN
OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
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WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
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PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.

		     END OF TERMS AND CONDITIONS

	    How to Apply These Terms to Your New Programs

  If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these terms.

  To do so, attach the following notices to the program.  It is safest
to attach them to the start of each source file to most effectively
convey the exclusion of warranty; and each file should have at least
the "copyright" line and a pointer to where the full notice is found.

    <one line to give the program's name and a brief idea of what it does.>
    Copyright (C) <year>  <name of author>

    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 2 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, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA


Also add information on how to contact you by electronic and paper mail.

If the program is interactive, make it output a short notice like this
when it starts in an interactive mode:

    Gnomovision version 69, Copyright (C) year name of author
    Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
    This is free software, and you are welcome to redistribute it
    under certain conditions; type `show c' for details.

The hypothetical commands `show w' and `show c' should show the appropriate
parts of the General Public License.  Of course, the commands you use may
be called something other than `show w' and `show c'; they could even be
mouse-clicks or menu items--whatever suits your program.

You should also get your employer (if you work as a programmer) or your
school, if any, to sign a "copyright disclaimer" for the program, if
necessary.  Here is a sample; alter the names:

  Yoyodyne, Inc., hereby disclaims all copyright interest in the program
  `Gnomovision' (which makes passes at compilers) written by James Hacker.

  <signature of Ty Coon>, 1 April 1989
  Ty Coon, President of Vice

This General Public License does not permit incorporating your program into
proprietary programs.  If your program is a subroutine library, you may
consider it more useful to permit linking proprietary applications with the
library.  If this is what you want to do, use the GNU Library General
Public License instead of this License.