sub do_rand {
    my $min = shift;
    my $len = shift;
    {
        my $n = "";
        for (1 .. $len)
        {
            $n .= chr( rand(255-$min)+$min );
        }

        if ($min == 0 && $n !~ /\x00/) {
           print("REDO!\n");
           redo;
        }
        return $n;
    }
}