Sample parser for radiotap header

Sample parser for radiotap header

[Roberto Riggio]

Hi,

I'm trying to update the radiotap support for the click
modular router. Where is the best place to look for
a C implementation of a radiotap parser?

R.

-- 
--------------------------------------------------------
Roberto Riggio, Ph.D.
CREATE-NET
Network&  Security Solutions for Pervasive Computing Systems (iNSPIRE)
Senior Researcher
Via alla Cascata 56/D - 38123 Povo Trento (Italy)
e-mail: roberto.riggio-2TmCWn7/4sHOQU1ULcgDhA@public.gmane.org
Tel: (+39) 0461 408400 - interno/extension 708
Fax: (+39) 0461 421157
www.create-net.org/~rriggio
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Re: Sample parser for radiotap header

[Johannes Berg]

On Wed, 2011-02-23 at 10:05 +0100, Roberto Riggio wrote:
> Hi,
> 
> I'm trying to update the radiotap support for the click
> modular router. Where is the best place to look for
> a C implementation of a radiotap parser?

There's a library linked on the website.

johannes

Re: Sample parser for radiotap header

[Bill Stafford]

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On Feb 23, 2011, at 01:05 AM, Roberto Riggio <roberto.riggio-2TmCWn7/4sFwQ27dvqrQYw@public.gmane.orgg> wrote:

Hi,

I'm trying to update the radiotap support for the click
modular router. Where is the best place to look for
a C implementation of a radiotap parser?

R.
 

The radiotap.org site has a section for Parser Libraries where it lists:
http://git.sipsolutions.net/radiotap.git/

-Bill


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Re: Sample parser for radiotap header

[Roberto Riggio]

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Il 24/02/2011 07:16, Bill Stafford ha scritto:
>
> The radiotap.org site has a section for Parser Libraries where it lists:
> http://git.sipsolutions.net/radiotap.git/
Is this supposed to know about extended present bitmask? I'm creating a
packet with four chained present bitmask in order to specify a MRR chain.

The problem is that when I'm trying to parse the header with the lib only
the first "block" is parsed. In fact when I use the function:

ieee80211_radiotap_iterator_next

I get ENOENT as return code when the bit 31 is reached. Same result
i I try to pass this packet to the linux kernel where the iterator 
implementation
is the same.
>
> -Bill
>


-- 
--------------------------------------------------------
Roberto Riggio, Ph.D.
CREATE-NET
Network&  Security Solutions for Pervasive Computing Systems (iNSPIRE)
Senior Researcher
Via alla Cascata 56/D - 38123 Povo Trento (Italy)
e-mail: roberto.riggio-2TmCWn7/4sHOQU1ULcgDhA@public.gmane.org
Tel: (+39) 0461 408400 - interno/extension 708
Fax: (+39) 0461 421157
www.create-net.org/~rriggio
--------------------------------------------------------

The information transmitted is intended only for the person or entity to
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Re: Sample parser for radiotap header

[Johannes Berg]

On Fri, 2011-02-25 at 19:36 +0100, Roberto Riggio wrote:

> Is this supposed to know about extended present bitmask? I'm creating
> a packet with four chained present bitmask in order to specify a MRR
> chain.
> 
> The problem is that when I'm trying to parse the header with the lib
> only the first "block" is parsed. In fact when I use the function:
> 
> ieee80211_radiotap_iterator_next
> 
> I get ENOENT as return code when the bit 31 is reached. Same result
> i I try to pass this packet to the linux kernel where the iterator
> implementation is the same.

You must be doing something wrong then, it is definitely parsing such
radiotap headers, hopefully correctly. There are examples in the check/
directory for it, e.g. 00.bin:
00000000  00 00 20 00 01 00 00 a0  01 00 00 00 00 00 00 00 
00000010  11 22 33 44 55 66 77 88  aa bb cc dd ee ff 00 11

is a radiotap header with two TSFT fields. I think you most likely
forgot to reset the namespace.

johannes

Re: Sample parser for radiotap header

[Roberto Riggio]

Il 02/03/2011 09:21, Johannes Berg ha scritto:
> You must be doing something wrong then, it is definitely parsing such
> radiotap headers, hopefully correctly. There are examples in the check/
> directory for it, e.g. 00.bin:
> 00000000  00 00 20 00 01 00 00 a0  01 00 00 00 00 00 00 00
> 00000010  11 22 33 44 55 66 77 88  aa bb cc dd ee ff 00 11
>
> is a radiotap header with two TSFT fields. I think you most likely
> forgot to reset the namespace.
Could you elaborate on this? What I'm doing is basically the following:

int ret = ieee80211_radiotap_iterator_init(&iterator, rthdr, skb->len, 
NULL);

the in the while loop i use:

ret = ieee80211_radiotap_iterator_next(&iterator);

and check the value of: iterator.this_arg_index

What do you mean by resetting the namespace?
> johannes

-- 
--------------------------------------------------------
Roberto Riggio, Ph.D.
CREATE-NET
Network&  Security Solutions for Pervasive Computing Systems (iNSPIRE)
Senior Researcher
Via alla Cascata 56/D - 38123 Povo Trento (Italy)
e-mail: roberto.riggio-2TmCWn7/4sHOQU1ULcgDhA@public.gmane.org
Tel: (+39) 0461 408400 - interno/extension 708
Fax: (+39) 0461 421157
www.create-net.org/~rriggio
--------------------------------------------------------

The information transmitted is intended only for the person or entity to
which it is addressed and may contain confidential and/or privileged
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Re: Sample parser for radiotap header

[Johannes Berg]

On Wed, 2011-03-02 at 09:42 +0100, Roberto Riggio wrote:
> Il 02/03/2011 09:21, Johannes Berg ha scritto:
> > You must be doing something wrong then, it is definitely parsing such
> > radiotap headers, hopefully correctly. There are examples in the check/
> > directory for it, e.g. 00.bin:
> > 00000000  00 00 20 00 01 00 00 a0  01 00 00 00 00 00 00 00
> > 00000010  11 22 33 44 55 66 77 88  aa bb cc dd ee ff 00 11
> >
> > is a radiotap header with two TSFT fields. I think you most likely
> > forgot to reset the namespace.

> Could you elaborate on this? What I'm doing is basically the following:

I think your radiotap header is malformed. Paste a hexdump and we can
help.

johannes

Re: Sample parser for radiotap header

[Johannes Berg]

On Wed, 2011-03-02 at 09:51 +0100, Roberto Riggio wrote:
> Il 02/03/2011 09:45, Johannes Berg ha scritto:
> > I think your radiotap header is malformed. Paste a hexdump and we can
> > help.
> 00002000 04040380 04000280 04000280 04000200 243c000c 00000000 00000000

Like I said, it's malformed. Cf.
http://radiotap.org/defined-fields/Radiotap%20Namespace

johannes

Re: Sample parser for radiotap header

[Roberto Riggio]

Il 02/03/2011 09:53, Johannes Berg ha scritto:
> Like I said, it's malformed. Cf.
> http://radiotap.org/defined-fields/Radiotap%20Namespace
So, every time I set bit 31 I must also set bit 29. What is a situation 
where
i should use bit 31 alone?
> johannes
>


-- 
--------------------------------------------------------
Roberto Riggio, Ph.D.
CREATE-NET
Network&  Security Solutions for Pervasive Computing Systems (iNSPIRE)
Senior Researcher
Via alla Cascata 56/D - 38123 Povo Trento (Italy)
e-mail: roberto.riggio-2TmCWn7/4sHOQU1ULcgDhA@public.gmane.org
Tel: (+39) 0461 408400 - interno/extension 708
Fax: (+39) 0461 421157
www.create-net.org/~rriggio
--------------------------------------------------------

The information transmitted is intended only for the person or entity to
which it is addressed and may contain confidential and/or privileged
material. Any review, retransmission, dissemination or other use of, or
taking of any action in reliance upon, this information by persons or
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divulgarlo anche in parte, distribuirlo ad altri soggetti, copiarlo,
od utilizzarlo per finalita' diverse, costituisce comportamento
contrario ai principi dettati dal D. Lgs. 196/2003.

Re: Sample parser for radiotap header

[Johannes Berg]

On Wed, 2011-03-02 at 10:01 +0100, Roberto Riggio wrote:
> Il 02/03/2011 09:53, Johannes Berg ha scritto:
> > Like I said, it's malformed. Cf.
> > http://radiotap.org/defined-fields/Radiotap%20Namespace

> So, every time I set bit 31 I must also set bit 29.

No.

>  What is a situation 
> where i should use bit 31 alone?

It's explained on the frontpage of radiotap.org.

johannes