#!/usr/bin/perl

$origserver="172.31.100.254";	# changed from $origserver="192.168.0.254"
$orignetwork="172.31.100.0";	# changed from $orignetwork="192.168.0.0"
$orignetmask="255.255.255.0";	

# the following line is buggy as it outputs "BROADCAST=aaa.bbb.ccc.ddd" it will be corrected
$origbroadcast = `/bin/ipcalc -b $orignetwork $orignetmask`;

# correction code for above bug  added in following line

@obcast=split '=',$origbroadcast;
$origbroadcast = @obcast[1];    # corrected form of $origbroadcast 

$config_file = "/etc/ltsp/dhcpd.conf";
$bkup_file = $config_file . ".ltsp.orig";
$tmp_file = $config_file . ".ltsp.tmp";

# don't bother to continue unless the target file exists
$exists = stat ($config_file);
if (! $exists) {
        print "\n". $config_file ." not found\n\n";
        exit;
}

# open target file
open (IN, "< $config_file");
open (OUT, "> $tmp_file");


if ( $ARGV[2] ) {
    $server = $ARGV[0];
    $network = $ARGV[1];
    $netmask = $ARGV[2];
} else {
    $server="172.31.100.254";
    $network="172.31.100.0";
    $netmask="255.255.255.0";
}
# the following line is buggy as it outputs "BROADCAST=aaa.bbb.ccc.ddd" it will be corrected 
$broadcast = `/bin/ipcalc -b $network $netmask`;

# correction code for above bug is added in the following line

@bc=split '=',$broadcast;
$broadcast = @bc[1];           # corrected form of $broadcast

@orignw = split '\.', $orignetwork;
@nw = split '\.', $network;
@nm = split '\.', $netmask;
$i = 0;
while ($nm[$i] == "255") {
    if ($net) {
        $net = $net . ".";
	$orignet = $orignet . ".";
         }
    $net = $net . $nw[$i];
    $orignet = $orignet . $orignw[$i];
    ++$i;
}
while (<IN>) {
    s/$origserver/$server/g;
    s/$orignetwork/$network/g;
    s/$orignetmask/$netmask/g;
    s/$origbroadcast/$broadcast/g;
    s/$orignet/$net/g;
    print OUT $_;
}

# close up the files
close (IN);
close (OUT);

# out with the old, in with the new
rename ($config_file, $bkup_file);
rename ($tmp_file, $config_file);

exit;