The attachment got somewhat dropped.
You can find it here
http://www.winpcap.org/gianluca/wlan_filtering.patch
GV
----- Original Message -----
From: "Gianluca Varenni" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Thursday, June 14, 2007 2:19 PM
Subject: [tcpdump-workers] Patches for wlan filtering
Guys,
the attached patch fixes some of the problems in the current wlan code
generation of pcap_compile.
In particular it should fix these problems:
1. the 802.11 header size of a data frame has not a fixed size. When the
QoS bit is set in the subtype field (QoS DATA frame), the header is two
bytes longer. You can clearly see this on 802.11n APs, that usually use
QoS DATA frames. The code does not take into consideration
* 802.11n frames containing the HT control field
* frames in a WDS (wireless bridges)
2. The optimizer generates buggy code when compiling filters in the form
"wlan dst ...." or similar. The optimizer gets disabled in these cases.
3. Added some code that verifies that a packet is a data frame when
accessing the LLC and above protocol fields.
Modifications related to 1. and 3. generate code that is not compatible
with the optimizer, as gen_load_ll_XXX() generate slist*'s of instructions
(where I added the code to verify if a packet is a data/QoS data frame),
and not block* chunks. So optimization gets disabled.
I'm planning to commit them on the libpcap CVS as disabled patches, and
also planning to enable them for the win32 build (winpcap) in the next
version that is probably due within some weeks.
Any comment/test is more than welcome. Please apply the patch with
"patch -p0 gencode.c < wlan_filtering.patch". The patch should work on
both HEAD and the libpcap_0_9 branch (I developed it on the libpcap_0_9
branch).
Have a nice day
GV
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