[PATCH 08/16] WNM: Move driver MBO transition rejection into wnm_is_bss_excluded

[Jouni Malinen]

On Mon, Apr 29, 2024 at 01:51:49PM +0200, benjamin at sipsolutions.net wrote:
> Change the logic a bit to not directly use the result of the
> wpa_drv_get_bss_trans_status call and instead use the same selection
> logic as usual but taking into account the driver rejections.
> 
> This changes the logic in minor ways. The main change is that this
> aligns the ordering of BSSs to be identical in all cases. More
> precisely, we'll select the best BSS as found by find_better_target.
> 
> Beyond that, it also means that in the case of an non-abridged BTM
> request we'll also consider candidates that were found through the scan
> and not in the neighbor report. In this case, the driver will not have a
> chance to reject them.

This feels a bit scary especially if the updated design has not actually
been tested with a driver that uses the driver-based mechanism for
updating candidate lists (which I'm assuming has not been done here).

And there is something strange here:

> diff --git a/wpa_supplicant/wnm_sta.c b/wpa_supplicant/wnm_sta.c
>  #ifdef CONFIG_MBO
> -static struct wpa_bss *
> -get_mbo_transition_candidate(struct wpa_supplicant *wpa_s,
> +static void
> +fetch_drv_mbo_candidate_info(struct wpa_supplicant *wpa_s,
>  			     enum mbo_transition_reject_reason *reason)
>  {

> +		if (nei->preference_present && nei->preference == 0)
>  			continue;
> +
> +		/* FIXME: Should we go through wpa_scan_res_match? */

Well, that is not the strange part, but again, something that makes me
unhappy about applying this without full testing.

> +#else
> +static void
> +fetch_drv_mbo_transition_candidate_info(struct wpa_supplicant *wpa_s)
> +{
>  }
>  #endif /* CONFIG_MBO */

That is the strange part.. What was that supposed to be? That same
function with empty payload? Now the function name is different and so
is the list of arguments. This would obviously not work without
CONFIG_MBO defined.

If this is just to skip the functionality within the function, defining
the function once with the actually body within #ifdef CONFIG_MBO would
be much cleaner.

-- 
Jouni Malinen                                            PGP id EFC895FA