RFC: libnetfilter_queue: nfq_udp_get_payload_len() gives wrong answer

[Duncan Roe <duncan_roe@optusnet.com.au>]

nfq_udp_get_payload() correctly returns a pointer to the first data byte in a
UDP message, e.g. to "A" in the message "ASD\n".

BUT nfq_udp_get_payload_len() returns 12 for the length of the above message,
i.e. combined lengths of payload and UDP header.

I plan to do an update of the documentation in src/extra/udp.c so I can document
this behaviour then.

OR

Should I change the behaviour of nfq_udp_get_payload_len() to what one would
expect? (e.g. return 4 in the example above)

OR

Should there be a new function, say nfq_udp_get_payload_len2(), to give the
expected answer?

AND, should the new or updated function guard against returning a -ve result?
(which, being unsigned, would become a large +ve result)

Any opinions?

Cheers ... Duncan.