On 26/01/2023 19:01, Petr Machata wrote: > In order to generate IGMPv3 and MLDv2 packets on the fly, we will need > helpers to calculate the packet checksum. > > The approach presented in this patch revolves around payload templates > for mausezahn. These are mausezahn-like payload strings (01:23:45:...) > with possibly one 2-byte sequence replaced with the word PAYLOAD. The > main function is payload_template_calc_checksum(), which calculates > RFC 1071 checksum of the message. There are further helpers to then > convert the checksum to the payload format, and to expand it. > > For IPv6, MLDv2 message checksum is computed using a pseudoheader that > differs from the header used in the payload itself. The fact that the > two messages are different means that the checksum needs to be > returned as a separate quantity, instead of being expanded in-place in > the payload itself. Furthermore, the pseudoheader includes a length of > the message. Much like the checksum, this needs to be expanded in > mausezahn format. And likewise for number of addresses for (S,G) > entries. Thus we have several places where a computed quantity needs > to be presented in the payload format. Add a helper u16_to_bytes(), > which will be used in all these cases. > > Signed-off-by: Petr Machata <petrm@xxxxxxxxxx> > --- > tools/testing/selftests/net/forwarding/lib.sh | 56 +++++++++++++++++++ > 1 file changed, 56 insertions(+) > Acked-by: Nikolay Aleksandrov <razor@xxxxxxxxxxxxx>
