Userspace mlme and detecting failed authentication attempt

Blaise Gassend blaise at willowgarage.com
Mon Jun 28 13:36:09 EDT 2010


Hi,

I am currently working on using wpa_supplicant as part of a roaming
streaming video app, and have a few questions that members of this list
may be able to help with:
http://www.willowgarage.com/pages/robots/texas/overview

Right now my main problem is that if association fails, it takes many
seconds before wpa_supplicant retries an association. I'm exploring
options to make this better. I have seen that you can adjust the
association timeout, but would rather a more robust solution where I
don't have to trade off excessive waiting time with the risk of
interrupting an association that is still making progress.

Here are the questions I am wondering about. Even a simple yes/no answer
would be really helpful in cutting down my search space.

1) Is there currently a mechanism for nl80211 to report to
wpa_supplicant that that the association failed?

2) Is there currently a way to get wpa_supplicant to use that mechanism,
or is that something that I would have to add?

I see that wpa_supplicant has a userspace mlme option, and my initial
thought would be easy to hack on if I want to fine-tune the association
process. According to config.mk that requires a kernel patch (the "vif"
patch, I believe). From digging through the mailing list, it looks like
this patch used to be linked to from the wpa_supplicant web page, but
the link no longer works. I have also seen commits to the kernel code
that suggest that support for userspace mlme has been removed.
(http://osdir.com/ml/linux-wireless/2009-03/msg01003.html)

So more questions:

3) Is userspace mlme obsolete?

4) Where can the kernel patch be found if I want to use it?

5) Apparently the "SME" API may be the replacement for userspace MLME.
Does wpa_supplicant use the SME API?

I have seen various threads where people discuss the merits of userspace
MLME and how many userspace MLME implementations there should be.
(http://www.mail-archive.com/netdev@vger.kernel.org/msg40483.html for
example) These were a while back, and I get the feeling that some
consensus was reached, but I haven't found the consensus written down
anywhere. 

6) Any pointers to what the outcome of that discussion was?

Thanks for any help,
Blaise



More information about the HostAP mailing list