message: Fixed crash under fuzz testing by using a saturating sub
diff: @@ -278,7 +278,7 @@ fn ipv4_option_length(option: &Ipv4OptionPacket) -> usize {
  fn ipv4_option_payload_length(ipv4_option: &Ipv4OptionPacket) -> usize {
  match ipv4_option.get_length().first() {
  - Some(len) => *len as usize - 2,
  + Some(len) => (*len as usize).saturating_sub(2),
  None => 0,
  }
  }
  