problems with dissecting

Alexander Chemeris alexander.chemeris at gmail.com
Fri Mar 1 06:39:26 UTC 2013


Ivan,

Could you please check whether this issue exists in the Wireshark dissector
as well? If yes, then we should submit a patch upstream.

Please excuse typos. Written with a touchscreen keyboard.

--
Regards,
Alexander Chemeris
CEO/Founder Fairwaves LLC
http://fairwaves.ru
On Mar 1, 2013 1:16 AM, "Ivan Kluchnikov" <Ivan.Kluchnikov at fairwaves.ru>
wrote:

> hi, andreas and steve!
>
> I fixed this problem, now decoding should work, you can check the last
> commit of master branch.
> There were problems with decoding and encoding of CSN_RECURSIVE_TARRAY,
> CSN_RECURSIVE_TARRAY_1, CSN_RECURSIVE_TARRAY_2.
>
>
> 2013/2/19 jolly <andreas at eversberg.eu>:
> > hi,
> >
> > steve and me experienced a problem with dissecting a "packet resource
> > request" at pcu. the patch i attached will show the following output:
> >
> > $ make && src/osmo-pcu
> >
> > PayloadType = 1 | spare = 0 | R = 0 | MESSAGE_TYPE = 5 |
> Exist_ACCESS_TYPE =
> > 1 | ACCESS_TYPE = 3 |  : ID | Choice PacketResourceRequestID = 1 |
> u.TLLI =
> > 0x7ee0e8fd | : End ID | Exist_MS_Radio_Access_capability = 1 |  :
> > MS_Radio_Access_capability | MS_RA_capability_value { | Choice
> > MS_RA_capability_value_Choice = 1 | u.Content length = 34 |
> > RF_Power_Capability = 4 | Exist_A5_bits = 1 | A5_bits = 96 | ES_IND = 1
> | PS
> > = 0 | VGCS = 0 | VBS = 0 | Exist_Multislot_capability = 1 |  :
> > Multislot_capability | Exist_HSCSD_multislot_class = 0 |
> > Exist_GPRS_multislot_class = 1 | GPRS_multislot_class = 10 ....
> >
> > this is all correct, but then i patched the get_ms_class_by_capability()
> > function at grps_rlcmac_data.c:
> >
> > ...
> > printf("we have = %d\n", cap->Count_MS_RA_capability_value);
> >         for (i = 0; i < cap->Count_MS_RA_capability_value; i++) {
> > printf("index=%d\n", cap->MS_RA_capability_value[i].IndexOfAccTech);
> > printf("exists multislot capability %d\n",
> > cap->MS_RA_capability_value[i].u.Content.Exist_Multislot_capability);
> > printf("exists class %d\n",
> >
> cap->MS_RA_capability_value[i].u.Content.Multislot_capability.Exist_GPRS_multislot_class);
> > printf("class %d\n",
> >
> cap->MS_RA_capability_value[i].u.Content.Multislot_capability.GPRS_multislot_class);
> > ...
> >
> > the output continues as this:
> >
> > we have = 2
> > index=2
> > exists multislot capability 0
> > exists class 1
> > class 10
> > index=0
> > exists multislot capability 0
> > exists class 0
> > class 0
> >
> > the "class 10" is correct, also it is correct that the class only exists
> in
> > the first entry of the capability array. the output of the dissector
> states
> > that multislot capability exists (Exist_Multislot_capability = 1), but
> if i
> > look at the structure, this field is not set.
> >
> > i looked at the dissector code, but don't really understand why
> > CSN_NEXT_EXIST works for some elements and not for others.
> >
> > any ideas?
> >
> > regards,
> >
> > andreas
> >
>
>
>
> --
> Regards,
> Ivan Kluchnikov.
> http://fairwaves.ru
>
>
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