#!/usr/bin/perl


# DHIS DNS Perl Engine by Dan Mahoney, please contact dhis@gushi.org with questions/comments/suggestions
# Last updated 9/25/2002

#Modified to fit to tinydns 1.05 by Nikademus nikademus@llorien.org

# Set this to the location of your dhis.db.
# You may need a different one.
$database = "/etc/dhis/db/dhis.db";

# Set this to the location of tinydns root on your system
# the directory where you can have the data file
$tinydnsroot = "/etc/tinydns/root";

# Set this to the IP this module should set for an offline host.
$offline = "192.168.255.0";

# Set this for the TTL a host should have.  60 was the DHIS original value.
$ttl = "60";

# logging setup.  By default DHIS has no way of logging the activity of the child processes
# so I added this kludge here.  It's heavy on file opens, but it's better to allow you to read
# the logfile in realtime (with tail -f) whereas if I didn't open so frequently the output would
# be buffered.

# set to 1 to turn on logging (only recommended for debugging)
$logging = "0";

# specify a log file.  The default will do but isn't very secure.
$logfile = "/tmp/dhis.log";

# set this to be whatever service you have defined in the DHIS service.db for this module
# otherwise this module will ignore the update requests
$thisservice = "dns";

########## End Of Configuration ##########


logthis("Starting up");
&cleardb;
&dbread;
&main;
logthis("EOF Received, exiting");

sub dbread {
  logthis("Reading database \"$database\"");
  open DATABASE, "$database" or die "Unable to read database $database";
  while (<DATABASE>) {
    $dbline = $_;

# This parse code works on my system, it may not work on yours, it assumes
# there are no spaces between your hostid and the beginning of the line.
# It also assumes you've followed the directions and put the curly brackets in.

    &logthis("reading database line \"$dbline\"");
    if ($dbline =~ /^(\d*)\s\{/) {
      &logthis("ID \"$1\" located");
      $currentid = $1;
    }
    if ($dbline =~ /hostname\s*(.*)\n/) {
      &logthis("setting hostname of host $currentid to \"$1\"");
      $hostname{$currentid} = "$1";
    }
  }
}

sub cleardb {
  foreach $key (keys %hostname) {
    delete $hostname{$key};
  }
}

sub main {

  while (<STDIN>) {
    $line = $_;
    if ($line =~ /reload/) {
      &logthis("reload command issued, reloading");
      &cleardb;
      &dbread;
      &logthis("database reload complete");
    }
    elsif ($line =~ /exit/) {
      &logthis("exit command received, exiting");
      close STDIN;
      exit 0;
    }

# add & update definitions
    elsif ($line =~ /add\s(\w*)\s(\d*)\s(.*)\n/ || $line =~ /update\s(\w*)\s(\d*)\s(.*)\n/) {
      &logthis("update received:\"$line\"");
      if (($hostname{$2}) && ($thisservice eq $1)) {
        &logthis("that's for $hostname{$2}");
	$newdata = "\+$hostname{$2}\:$3\:$ttl\n";
	update_zone();
      }
    }

# delete definition
    elsif ($line =~ /delete\s(\w*)\s(\d*)\s(.*)\n/) {
      &logthis("update received:\"$line\"");
      &logthis("that's for $hostname{$2}");
      if (($hostname{$2}) && ($thisservice eq $1)) {
        &logthis("thisservice = .$thisservice. and $1 is the arg");
	$newdata= "\+$hostname{$2}:$offline:$ttl\n";
	update_zone();
      }
    }
  }
}


sub logthis ($) {
  if ($logging eq 1) {
    $thing = shift;
    open LOGFILE, ">>$logfile";
    print LOGFILE "$thing\n";
    close LOGFILE;
  }
}

sub update_zone() {

	open (DATA, "<$tinydnsroot/data") || die print $!;
	@data=<DATA>;
	close (DATA);
	open (DATA, ">$tinydnsroot/data") || die print $!;
	for ($i=0;$i<@data;$i++) {
		if ($data[$i] =~ /\+$hostname{$2}\:([0-9]{1,3}\.){3}[0-9]{1,3}\:$ttl/ ) {
			print DATA $newdata;
			print $newdata;
		}
		else {
			print DATA $data[$i];
		}
	}
	close (DATA);
	system ("cd $tinydnsroot/ && /usr/local/bin/tinydns-data");
}