Re: [B.A.T.M.A.N.] [PATCH] batctl: Validate translated mac addresses

[Sven Eckelmann <sven@narfation.org>]

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On Samstag, 14. April 2018 04:34:42 CEST Antonio Quartulli wrote:
> 
> On 14/04/18 02:16, Sven Eckelmann wrote:
[...]
> We already handle the case of multiple originators handling the same MAC
> address, no? In that case I think we pick the "best" originator.

Yes, but this doesn't make a lot of sense for multicast and zero mac 
addresses. The translate layer of batctl is usually used to ping/traceroute to 
some originator. But multicast and zero mac addresses don't represent a 
"client" which can be used to identify some originator. So it doesn't seem to 
make sense to allow them here.

Or even without the ping/traceroute stuff, the concept of calling `batctl 
translate` should give you an answer which you can understand. So it should 
tell you that batman-adv is very likely to transmit a unicast packet with this 
destination address to this originator. But this cannot work for multicast 
destination addresses because multiple answer should be given here - which is 
out of scope for this command. Which reminds me that I should propose a second 
patch which checks whether the input for translate_mac is "valid" before 
trying to translate it.

> This case sounds more like a validity check because "a zero MAC should
> not be in the translation table", or am I wrong?

Partially, yes. I personally don't care (at the moment) whether there is a 
zero mac address in the translation table. The current translation table code 
(batadv_tt_local_add) doesn't check whether there is a zero mac address 
(is_zero_ether_addr). But Linus had some ideas when zero mac addresses can be 
useful - maybe he tell us whether it makes sense/problems to have them in the 
translation table.

Kind regards,
	Sven

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