From: Sven Eckelmann <sven@narfation.org>
To: b.a.t.m.a.n@lists.open-mesh.org
Subject: Re: [PATCH v6 2/3] batman-adv: mcast: implement multicast packet generation
Date: Sat, 29 Jul 2023 12:49:29 +0200 [thread overview]
Message-ID: <2654113.Lt9SDvczpP@sven-l14> (raw)
In-Reply-To: <20230720043556.12163-3-linus.luessing@c0d3.blue>
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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.luessing@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 <sven@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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next prev parent reply other threads:[~2023-07-29 10:49 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-20 4:35 [PATCH v6 0/3] Implementation of a Stateless Multicast Packet Type Linus Lüssing
2023-07-20 4:35 ` [PATCH v6 1/3] batman-adv: mcast: implement multicast packet reception and forwarding Linus Lüssing
2023-07-28 17:52 ` Sven Eckelmann
2023-08-14 15:35 ` Simon Wunderlich
2023-08-14 15:53 ` Simon Wunderlich
2023-07-20 4:35 ` [PATCH v6 2/3] batman-adv: mcast: implement multicast packet generation Linus Lüssing
2023-07-29 10:49 ` Sven Eckelmann [this message]
2023-07-20 4:35 ` [PATCH v6 3/3] batman-adv: mcast: shrink tracker packet after scrubbing Linus Lüssing
2023-07-29 11:11 ` Sven Eckelmann
2023-08-14 15:56 ` Simon Wunderlich
2023-07-29 11:11 ` [PATCH v6 0/3] Implementation of a Stateless Multicast Packet Type Sven Eckelmann
2023-08-14 16:05 ` Sven Eckelmann
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