my $flag1 = substr $packet, 0, 8;
    my $byte_count = substr $packet, 9, 16;
    my $num_bytes = convert_byte_count($byte_count);
    my $payload = substr $packet, 25, $num_bytes * 8;
    my $flag2 = substr $packet, 25 + $num_bytes * 8, 8;