Define stateless functions to validate the checksum of an ip header and of a udp packet and use them in get_raw_packet().
Define stateless functions to validate the checksum of an ip header and of a
udp packet and use them in get_raw_packet().

Print a warning if the raw UDP receive gets a quantum of data that is greater
than that of a single UDP datagram.

Remove unnecessary argument from net_checksum().  Initializing a nonzero
checksum value is not very helpful in practice.

Define a function net_checksum_add() that, for two sequences of bytes A and B
that return checksums CS(A) and CS(B), will calculate the checksum CS(AB) of
the concatenated value AB given the checksums of the individual parts CS(A)
and CS(B).

niklata/ndhc