Re: [B.A.T.M.A.N.] [PATCH 3/5] batman-adv: enable roaming packets to carry flags

[Antonio Quartulli <ordex@autistici.org>]

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On Tue, Jun 26, 2012 at 11:45:37PM +0200, Matthias Schiffer wrote:
> On 06/26/2012 11:22 PM, Sven Eckelmann wrote:
> > On Tuesday 26 June 2012 22:00:20 Antonio Quartulli wrote:
> >> In case of client-roaming it would be useful to carry TT flags along with
> >> the client entry. Information contained in the flags could be used on the
> >> new mesh node for several reasons (e.g. particular roaming treatment).
> >>
> >> This patch modifies the ROAMING_ADV packet according to this idea so that it
> >> can also carry the flags together with the MAC address of the moving
> >> client.
> >>
> >> Signed-off-by: Antonio Quartulli <ordex@autistici.org>
> >> ---
> >>  packet.h            |    2 +-
> >>  routing.c           |    7 ++++---
> >>  translation-table.c |   17 ++++++++++-------
> >>  3 files changed, 15 insertions(+), 11 deletions(-)
> >>
> >> diff --git a/packet.h b/packet.h
> >> index 65d66e4..e0b94a3 100644
> >> --- a/packet.h
> >> +++ b/packet.h
> >> @@ -214,7 +214,7 @@ struct batadv_tt_query_packet {
> >>
> >>  struct batadv_roam_adv_packet {
> >>  	struct batadv_header header;
> >> -	uint8_t  reserved;
> >> +	uint8_t  flags;
> >>  	uint8_t  dst[ETH_ALEN];
> >>  	uint8_t  src[ETH_ALEN];
> >>  	uint8_t  client[ETH_ALEN];
> > 
> > I am not 100% sure because I haven't checked the code, but couldn't it be the 
> > case that we send random bits inside reserved at the moment? At least I cannot 
> > remember the part of the code that initialized reserver to any specific value. 
> > That would make the change incompatible with older batman-adv version.
> 
> As stated in an earlier mail, the `reserved' field in the vis packets
> isn't initialized either, leading to the same problem, being unable to
> ever use this field for anything when you want to stay compatible with
> older versions.
> 
> IMO this should be fixed in all packets, it's a really bad idea to send
> uninitialized memory over the network...

Yes, I agree. we have to remember this fix the next time we decide to break
compatibility. I don't think we are going to do it now.

Cheers,




-- 
Antonio Quartulli

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

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