Re: [B.A.T.M.A.N.] [PATCH] batman-adv: limit local translation table max size

[Antonio Quartulli <ordex@autistici.org>]

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On Mon, Sep 02, 2013 at 12:49:03AM +0800, Marek Lindner wrote:
> On Sunday, September 01, 2013 16:05:43 Antonio Quartulli wrote:
> > > Upon reading this function a realized this "tt_diff_len = 0" mechanism is
> > > buggy. For instance, the changes_list list is not purged but keeps
> > > growing until it magically fits the ogm diff again. Or checking
> > > bat_priv->soft_iface-
> > > 
> > > >mtu isn't terribly accurate either. The more I looked the more my head
> > > 
> > > started to spin. Suddenly, I was convinced we don't need the check
> > > anymore because we have the fragmentation but you are right - it won't
> > > help here. I'll add the check again but be aware that it is broken.
> > 
> > Right, there is a bug. We should purge the list in any case, even if
> > tt_diff_len is 0.
> > 
> > Yes, checking tt_diff_len against bat_priv->soft_iface->mtu is probably not
> > correct..shall we check it against the mtu of the primary interface?
> > Anyway, this is outside the scope of this patch.
> 
> Checking the primary interface is not enough either. You would need to know 
> how much space is left in the OGM itself (assuming nobody else is going to 
> occupy it before you do). All registered tvlvs and their content have to be 
> taken into account. As well as headers and other stuff ...

Looks like an interesting problem :)
Moreover, assuming we prepare a "correct OGM" it may be the case that the mtu is
changed later (after preparing but before sending it).

Cheers,

-- 
Antonio Quartulli

..each of us alone is worth nothing..
Ernesto "Che" Guevara

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