problems with dissecting

Ivan Kluchnikov Ivan.Kluchnikov at fairwaves.ru
Fri Mar 1 08:45:35 UTC 2013


Yes, this issue exists in the Wireshark too, but it is not critical
there, because dissector displays decoding of this message correct.
In any case, I will prepare a patch.

2013/3/1 Alexander Chemeris <alexander.chemeris at gmail.com>:
> 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
>>
>



-- 
Regards,
Ivan Kluchnikov.
http://fairwaves.ru




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