Subject: Re: bpf, net80211 and FCS
To: David Young <dyoung@pobox.com>
From: Eric Auge <eau@phear.org>
List: tech-kern
Date: 06/03/2005 09:35:10
This is an OpenPGP/MIME signed message (RFC 2440 and 3156)
--------------enig7F4C95AA9B38117677E44D02
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit



David Young wrote:
> Eric,
> 
> The FCS is ordinarily stripped before BPF-tapping because apps do not
> expect for it to be present.  For your app, consider using radiotap
> (DLT_IEEE802_11_RADIO).  The radiotap header may contain a flag,
> IEEE80211_RADIOTAP_F_FCS, that tells whether there is an FCS in the last
> four bytes of a tapped frame.

hmm ok i missed something then...thanks for information.

> 
> All 802.11 NICs check the FCS.  Most NICs will indicate to the driver
> whether the FCS was correct or not.  The radiotap header was designed
> to carry that kind of "meta-information" about frames.  If you were
> so inclined, you could modify the drivers to set a "FCS (in)correct"
> flag in the radiotap header, and submit a patch. :-)

right, I first wanted to ask if I was not missing something obvious,
and to get an idea of a clean patch, which you gave.

I'll do one and submit here for review, or should I send-pr ?

Thanks for your help,
Regards,
Eric.
> 
> Dave
> 

--------------enig7F4C95AA9B38117677E44D02
Content-Type: application/pgp-signature; name="signature.asc"
Content-Description: OpenPGP digital signature
Content-Disposition: attachment; filename="signature.asc"

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.1 (NetBSD)

iD8DBQFCoAg1SdZNA80H8MYRAjiaAKCLIR/bpVzFUZg1BXR1Ro7BgIpcDgCgibvr
DcvrTl35n9pFdFaGlmdMVyc=
=Ms/e
-----END PGP SIGNATURE-----

--------------enig7F4C95AA9B38117677E44D02--