Re: [B.A.T.M.A.N.] [PATCH maint 3/3] batman-adv: do not modify batadv packet header before pulling it

[Matthias Schiffer <mschiffer@universe-factory.net>]

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On 03/18/2018 09:15 AM, Sven Eckelmann wrote:
> On Freitag, 16. März 2018 11:29:11 CET Matthias Schiffer wrote:
>> batadv_check_unicast_ttvn() may modify the batadv header, leading to
>> checksum errors in the following processing of the packet.
>>
>> Rather than fixing up the checksum, simply pull the batadv header before
>> modifying it (and push it back in case the packet is rerouted).
>>
>> Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
>> ---
> 
> This patch is so invasive that it breaks the batadv_dbg_arp check which you've 
> just fixed a patch before.
> 
> Kind regards,
> 	Sven
> 

Yes, it's the main reason I improved the check; I should have mentioned
that in the commit message. As mentioned on IRC, batadv_dbg_arp will still
print what information is added to the DAT cache, but it can't tell which
batadv packet type the ARP packet was encapsulated in anymore (this
information is still available through `batctl td`).

In my further cleanup patches, I plan to

* make the broadcast case match as well (pull before calling snooping
functions)
* move snooping calls to batadv_interface_rx
* remove header size argument from incoming snooping functions (will always
be 0)
* remove the now dead code from batadv_dbg_arp

This will improve symmetry between the incoming and outgoing snooping paths.

Matthias


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