Re: [PATCH v3 4/5] batman-adv: mcast: implement multicast packet generation

Implement the preparation of a batman-adv multicast packet and use this under certain conditions. For one thing this implements the capability to push a complete batman-adv multicast packet header, including a tracker TVLV with all originator destinations that have signaled interest in it, onto a given ethernet frame with an IP multicast packet inside. For another checks are implemented to determine if encapsulating a multicast packet in this new batman-adv multicast packet type and using it is feasible. Those checks are: 1) Have all nodes signaled that they are capable of handling the new batman-adv multicast packet type? 2) Do all active hard interfaces of all nodes, including us, have an MTU of at least 1280 bytes? 3) Does a complete multicast packet header with all its destination addresses fit onto the given multicast packet / ethernet frame and does not exceed 1280 bytes? If all checks passed then the new batman-adv multicast packet type will be used for transmission and distribution. Otherwise we fall back to one or more batman-adv unicast packet transmissions, if possible. Or if not possible we will fall back to classic flooding through a batman-adv broadcast packet. Signed-off-by: Linus Lüssing <linus.luessing(a)c0d3.blue> --- net/batman-adv/multicast.c | 79 ++++- net/batman-adv/multicast.h | 24 +- net/batman-adv/multicast_forw.c | 511 ++++++++++++++++++++++++++++++++ net/batman-adv/soft-interface.c | 6 +- net/batman-adv/types.h | 6 + 5 files changed, 618 insertions(+), 8 deletions(-)