> OK, I'm not against it, but I don't know of any standard way to indicate
> whether the packet has valid FCS or not. I believe such flag would be
> useful for Kismet and other tools. I don't feel good about lumping all
> packets together without having a flag to tell good ones from corrupted
> ones.
>
> I see that AVS headers have made it into the kernel
> (drivers/net/wireless/prism54/islpci_eth.h), but there is no place for
> CRC flag in them. Could you ask linux-wlan-ng developers to add such
> flag?
Currently being discussed on the ipw2x00 list is the 80211 kernel stack
(partially in 2.6.12). Part of the discussion centers around
appropriate per-packet statistics headers. The current main focus of
the conversation is Radiotap headers -- these are in use on Net, Free,
and OpenBSD and exist in some state in linux in the madwifi drivers (Sam
implemented them on FreeBSD).
I believe these already have room for a known-invalid flag and if they
don't I'll request one (should linux adopt them). The RT headers are
basically a 32bit bitfield signifying what values are included, followed
by those data sets, in order. Bit 32 signifies another 32 (or 64, I
forget off the top of my head) bitfield following the initial bitfield,
for future expansion.
Think of RT as super-avs, with cross-os compatability. Ethereal (and
maybe tcpdump) and kismet all already understand it. If it looks like
we may not be moving to radiotap, I'll get in touch with the avs folks.
You can see the RT headers here:
http://cvsweb.netbsd.org/bsdweb.cgi/src/sys/net80211/ieee80211_radiotap.h?rev=1.11&content-type=text/x-cvsweb-markup
Radiotap, incidentally, also solves the FCS problem by defining header
flags for if we have it or not.
As you can probably guess, I'm growing to like the RT headers.
-m
--
Quidquid Latine Dictum Sit, Altum Viditur
(Anything said in latin sounds profound)
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