search

P1sec / pycrate

A Python library to ease the development of encoders and decoders for various protocols and file formats; contains ASN.1 and CSN.1 compilers.
GNU Lesser General Public License v2.1
381 stars 132 forks source link

Feature Group Indicators LTE UE Capability #168

Closed ritgail closed 2 years ago

ritgail commented 2 years ago

Hi Developers,

I was trying to decode UE capability information on LTE UL_DCCH message. I used the below codes: lte_ue_capability(unhexlify('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'))

def lte_ue_capability(payload): request = RRCLTE.EUTRA_RRC_Definitions.UE_EUTRA_Capability request.from_uper(payload) jsonObject = json.loads(request.to_json()) return jsonObject

I am able to get the result, but I need feature group indicator values. Currently, it is showing in Hex.

Is it already implemented to decode? Thanks for your support. uecapability.txt

p1-bmu commented 2 years ago

featureGroupInd* are all defined as BIT STRING (SIZE (32)) in the LTE RRC ASN.1 specification. Pycrate does not provide additional decoding for those fields. You need to check annexes B.1 and C.1 of the 3GPP TS 36.331, which describe how those fields are encoded (what seems fairly complex at 1st sight...).

ritgail commented 2 years ago

I can try to populate these fields similar to wireshark.

Could you guide me how to do that with the BIT STRING. I can see it is now like: _UE_EUTRA_Capability_featureGroupIndicators = BIT_STR(name=u'featureGroupIndicators', mode=MODE_TYPE, tag=(6, TAG_CONTEXT_SPEC, TAG_IMPLICIT), opt=True) _UE_EUTRA_Capability_featureGroupIndicators._const_sz = ASN1Set(rv=[32], rr=[], ev=None, er=[])

image

p1-bmu commented 2 years ago

Ideally, you would have to change the ASN.1 definitions of the different objects featureGroupInd* in the file EUTRA-RRC-Definitions.asn, to define named bits (see e.g. https://www.oss.com/asn1/resources/asn1-made-simple/types.html). You would have then to recompile the LTERRC ASN.1 spec. Finally, you should be able to access the named bits after decoding a buffer through one of the following methods: