[rt2x00-users] Alignment, padding and IV/ICV
Gertjan van Wingerde
gwingerde at gmail.com
Tue Dec 1 21:24:51 UTC 2009
On 12/01/09 22:09, Benoit PAPILLAULT wrote:
> OK. My feeling is that if we try to achieve header alignment + payload
> alignment + L2 pad at the same time, it will not work. For instance,
> with an ACK frame (header_length=10, l2pad=0), we cannot align both
> header + payload.
But an ACK frame won't have any payload, so no l2pad and no payload align (as
there is no payload).
> If we align header for all frames + payload for data frame only, we then
> have :
> - control frame : hdrlen = 16 so if we align header, payload will be
> align, except for ACK/CTS (hdrlen=10), which we don't care.
> - invalid frame : we don't care, no padding
> - data frame : if we align header+payload, L2pad will be OK as well
> (since hdrlen+l2pad is always a multiple of 4).
> - management frame : hdrlen=24, already multiple of 4. So alignment of
> header will also align the payload.
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