On Thursday, 20 July 2023 06:35:54 CEST Linus Lüssing wrote: > 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.luess...@c0d3.blue> > --- > net/batman-adv/multicast.c | 79 +++- > net/batman-adv/multicast.h | 25 +- > net/batman-adv/multicast_forw.c | 727 ++++++++++++++++++++++++++++++++ > net/batman-adv/soft-interface.c | 6 +- > net/batman-adv/types.h | 6 + > 5 files changed, 835 insertions(+), 8 deletions(-)
Acked-by: Sven Eckelmann <s...@narfation.org>
> +/**
> + * batadv_mcast_forw_scrape() - remove bytes within skb data
> + * @skb: the skb to remove bytes from
> + * @offset: the offset from the skb data from which to scrape
> + * @len: the amount of bytes to scrape starting from the offset
> + *
> + * Scrapes/removes len bytes from the given skb at the given offset from the
> + * skb data.
> + *
> + * Caller needs to ensure that the region from the skb data's start up
> + * to/including the to be removed bytes are linearized.
> + */
> +static void batadv_mcast_forw_scrape(struct sk_buff *skb,
> + unsigned short offset,
> + unsigned short len)
> +{
> + char *to = skb_pull(skb, len), *from = to - len;
> +
> + memmove(to, from, offset);
> +}
Just because I remembered it when reading a comment: SKB_LINEAR_ASSERT(skb)
might be a good idea in places like this. Not all over the place but actually
in the code which operates on the buffer and assumes the skbuff to be
linearized. skb_put would do such a check (because it is a put at the end of
the skb) but not an skb_pull.
Kind regards,
Sven
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