Message-ID: <4FE9E201.1010903@opentechinstitute.org> (sfid-20120626_182337_227242_2D9BB481)
Date: Tue, 26 Jun 2012 12:23:29 -0400
From: Will Hawkins <hawkinsw@opentechinstitute.org>
MIME-Version: 1.0
To: Johannes Berg <johannes@sipsolutions.net>
CC: Will Hawkins <hawkinsw@opentechinitiative.org>,
	linux-wireless@vger.kernel.org
Subject: Re: Help tracing NL80211_CMD_AUTHENTICATE as event in IBSS mode
References: <24f-4fe93400-17-239c5900@2266046>  (sfid-20120626_061218_757773_249E152D) <1340693584.4662.3.camel@jlt3.sipsolutions.net>
In-Reply-To: <1340693584.4662.3.camel@jlt3.sipsolutions.net>
Content-Type: text/plain; charset=UTF-8
Sender: linux-wireless-owner@vger.kernel.org


On 06/26/2012 02:53 AM, Johannes Berg wrote:
> Hi,
> 
>> The documentation for nl80211 says the following about the
>> NL80211_CMD_AUTHENTICATE command:
>> "When used as an event, this reports reception of an Authentication
>> frame in station and IBSS modes when the local MLME processed the
>> frame, i.e., it was for the local STA and was received in correct
>> state."
>>
>> I very much want this to be true for IBSS modes. However, I cannot
>> seem to trace through the source code to confirm that this actually
>> happens. I can easily follow the code for the case when the interface
>> is in station mode but lose the trail for IBSS. 
> 
> I'm afraid that isn't actually true for IBSS. The event you get there
> will be NL80211_CMD_NEW_STATION.

Thank you for the sanity check! Do you think it's worthwhile to patch
the nl80211.h file to address this?

> 
>> As far as I can tell, the only path to nl80211_send_rx_auth (the only
>> place a NL80211_CMD_AUTHENTICATE command is sent to userspace) looks
>> like this:
>> ieee80211_iface_work invokes ieee80211_sta_rx_queued_mgmt to handle
>> queued management packets received on a station interface.
>> ieee80211_sta_rx_queued_mgmt (eventually) invokes
>> cfg80211_send_rx_auth, after the proper handling. Finally,
>> cfg80211_send_rx_auth invokes nl80211_send_rx_auth.
> 
> Yes.
> 
> 
> I think in your case though, what you really want is a NL80211_CMD_FRAME
> event? You register for auth frames, also to prevent mac80211 from
> handling them itself, and then they get diverted to cfg80211_rx_mgmt()
> and on to nl80211_send_mgmt().

Thanks for this, as well. As far as the patch that I submitted, you are
exactly correct. I was only investigating this other method since it
appears that's how wpa_supplicant claims to support IBSS RSN.
wpa_supplicant never actually registers for AUTH frames (through
NL80211_CMD_REGISTER) and relies solely on the NL80211_CMD_AUTHENTICATE
to actually receive copies of those frames.

Thanks again. My forehead was getting sore from all the banging!
Will

> 
> johannes
> 
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