/* Returns the IP checksum of the 'n' bytes in 'data'.
*
* The return value has the same endianness as the data. That is, if 'data'
* consists of a packet in network byte order, then the return value is a value
* in network byte order, and if 'data' consists of a data structure in host
* byte order, then the return value is in host byte order. */
/* Returns the IP checksum of the 'n' bytes in 'data'.
*
* The return value has the same endianness as the data. That is, if 'data'
* consists of a packet in network byte order, then the return value is a value
* in network byte order, and if 'data' consists of a data structure in host
* byte order, then the return value is in host byte order. */