P2P Channel list: Applying regulatory rules

Jouni Malinen j
Wed Dec 17 09:41:36 PST 2014

On Wed, Dec 17, 2014 at 09:05:47PM +0530, Krishna Chaitanya wrote:
> P2P spec 1.5 tells that:
> > The Channel List attribute shall indicate the channels that the P2P Device can support as Operating Channel of the P2P Group if it becomes P2P Group Owner.

Please keep in mind that this is in a section that specifically
discusses GO Negotiation Request and as such, that sentence doesn't have
much to do with what other frame with the Channel List attribute may do.

> So in p2p_buf_add_channel_list We should take in to account the
> reg_class flags and accordingly should avoid NO_IR/RADAR/PASSIVE-SCAN
> channels from the channel list? because we cannot start AP operation
> in those channels.

Not in that function since it is used for other purposes than just GO
Negotiation Request.

> How do we handle Auto-GO/non-Auto-GO, for regulatory rules. Spec is
> not clear about this.

There are large number of unclear parts related to how the operating
channel can get negotiated in number of corner cases (and even not so
corner cases).

> I am preparing a patch to remove those channels for now, later we can
> extend to check for DFS availability also.
> But want to confirm before spending too much time.

If I understood what you are proposing, I would be quite unlikely to
accept such a change. This area in P2P has required significant
fine-tuning to cover practical use cases and I'm not going to be undoing
those based on that one sentence in the spec.

None of the DFS channels are included in the P2P channel list now
anyway and there is already quite a bit of conditions removing channels
on which the device cannot become a GO. If you have a specific example
of a case where some channels should be removed, I'd suggest providing a
wpa_supplicant debug log and sniffer capture of an exchange as a
justification for a proposed change. Without those, I don't think I'd
accept changes in this area.
Jouni Malinen                                            PGP id EFC895FA

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