message: Fix "attempt to subtract with overflow" in tcp_option_payload_length()
diff: @@ -203,9 +203,9 @@ fn tcp_option_length(option: &TcpOptionPacket) -> usize {
  }
  fn tcp_option_payload_length(ipv4_option: &TcpOptionPacket) -> usize {
  - match ipv4_option.get_length().first() {
  - Some(len) => *len as usize - 2,
  - None => 0,
  + match ipv4_option.get_length_raw().first() {
  + Some(len) if *len >= 2 => *len as usize - 2,
  + _ => 0,
  }
  }
  