Radiotap header parsing

[piotr...@sens.us]

Hi,

first of all thanks for an excellent library.
But I think I found a bug on radiotap header parsing - although according to spec it is 8 bytes long, in my capture (included sample) it is padded to 34.
I am on 64bit machine, maybe that is the reason or maybe it is something else (mac8011 padding?)

Anyway it_len field is set correctly so it can be used during parsing and calculating length of data after it.
Here is a patch for that, checked it against v0.3 because current version in git does not build for me (some make problems)

BTW. the capture file contains another one problematic packet (#157) with QoS Null function, parsing fails on it as well, not sure if it is fixed in latest due to problems stated.

Kind regards
Piotr

[Matias Fontanini]

Hi Piotr,

Thanks a lot for the patch! I'll be applying it in a while, and will have a look at the QoS Null function packet bug. RadioTap has not been tested enough so as to ensure every packet is parsed right. I'm going to search for more packet samples and add some test cases soon.

As for the make problem when using the current version of the library, found in the git repository, yes, yesterday I modified something and it seems like it's somehow broken. I'll put my hands on that later today.

Thanks again for the patch, I'll let you know when the QoS Null function packet is parsed correctly.

Cheers,
Matias

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[Matias Fontanini]

Hello again,

I've applied the patch, and fixed an issue that it introduced when the packet used a FCS. Moreover, it looks like the Makefile is fixed. I'd appreciate it if you could pull the repository and tried to compile the library though.

Finally, the issue when parsing the QoS Null function packet is fixed. Note that that packet will contain a Dot11QoSData object.

Thanks again for your report and patch.

Cheers,
Matias

[Piotr Haber]

Hi,

thanks for the fixes and sorry for extra work about the FCS,

radiotap is not the best documented format i've seen...

i did compile the library ok, will continue tomorrow

BTW. there is this other flag 

0x20 : frame has padding between 802.11 header and payload (to 32-bit boundary)

but i did not see it used anywhere

Cheers.

[Matias Fontanini]

No problem, the test cases made the error easy to spot. Thanks for
compiling it, I'm glad it finally works.

I'll put my hands on those radiotap fields that are missing in the
library soon.

Cheers.