_ChecksumData
uint16 _ChecksumData(const void* data, uint16 length, ip_addr_t source,
uint16 _ChecksumData(const void *data, uint16 length, ip_addr_t source,
uint16 chksum = _ChecksumData(data, size, sourceIP, destinationIP);
&& _ChecksumData(data, length, sourceIP, destinationIP) != 0)) {