Wireshark · Wireshark-dev: Re: [Wireshark-dev] NBAP -> RRC Help

["Anders Broman" <anders.broman@xxxxxxxxxxxx>]

Hi,

Abstracts from the ASN1 descriptions:

NBAP:

IB-SG-DATA ::= BIT STRING

-- Contains SIB data fixed" or "SIB data variable" in segment as encoded in ref.[18].

RRC

SIB-Data-fixed ::= BIT STRING (SIZE (222))

SIB-Data-variable ::= BIT STRING (SIZE (1..214))

In principle you could "export" SIB-Data-fixed  and SIB-Data-variable dissection from RRC, include packet-rrc.h in NBAP and use the metodes

there but as yopu can see that wouldn't add much...

 

From a quick read of the spec it's not clear to me if

 iB-Type: mIB (0)
Idicates that the field actually contains a masterInformationBlock and could be decoded as such.

 

Regards

Anders

---

From: wireshark-dev-bounces@xxxxxxxxxxxxx [mailto:wireshark-dev-bounces@xxxxxxxxxxxxx] On Behalf Of Rick Bywater
Sent: den 10 november 2009 15:21
To: wireshark-dev@xxxxxxxxxxxxx
Subject: [Wireshark-dev] NBAP -> RRC Help

All,

I am looking at the NBAP dissector to correct/complete 
its decode of IB_SG_DATA.  According to the specifications, the IB_SG_DATA 
has RRC encoding.  So, for each IE IB_SG_DATA IE, the RRC dissector for 
that segment (presumably) should be called.  Currently, those IEs simply 
decode as bit string?  Here is an abbreviated section of the decode I am 
talking about:

Frame 1 (330 bytes on wire, 330 bytes 
captured)
Ethernet II, Src: Dell_ed:a0:a4 (00:11:43:ed:a0:a4), Dst: 
DellComp_f2:3c:f1 (00:b0:d0:f2:3c:f1)
Internet Protocol, Src: 172.16.5.201 
(172.16.5.201), Dst: 10.30.86.200 (10.30.86.200)
Stream Control Transmission 
Protocol, Src Port: 49153 (49153), Dst Port: 49152 (49152)
UTRAN Iub 
interface NBAP signalling
    NBAP-PDU: initiatingMessage 
(0)
        
initiatingMessage
            
procedureID
                
procedureCode: id-systemInformationUpdate 
(32)
                
ddMode: common 
(2)
            
criticality: reject 
(0)
            
messageDiscriminator: common 
(0)
            
transactionID: longTransActionId 
(1)
                
longTransActionId: 
80
            
value
                
SystemInformationUpdateRequest
                    
protocolIEs: 2 
items
                        
Item 0: 
id-C-ID
                            
ProtocolIE-Field
                                
id: id-C-ID 
(25)
                                
criticality: reject 
(0)
                                
value
                                    
C-ID: 
0
                        
Item 1: 
id-MIB-SB-SIB-InformationList-SystemInfoUpdateRqst
                            
ProtocolIE-Field
                                
id: id-MIB-SB-SIB-InformationList-SystemInfoUpdateRqst 
(134)
                                
criticality: reject 
(0)
                                
value
                                    
MIB-SB-SIB-InformationList-SystemInfoUpdateRqst: 7 
items
                                        
Item 
0
                                            
MIB-SB-SIB-InformationItem-SystemInfoUpdateRqst
                                                
iB-Type: mIB 
(0)
                                                
iB-OC-ID: 
1
                                                
deletionIndicator: no-Deletion 
(0)
                                                    
no-Deletion: 
id-SegmentInformationListIE-SystemInfoUpdate
                                                        
iB-SG-REP: rep8 
(1)
                                                        
segmentInformationList
                                                            
id: id-SegmentInformationListIE-SystemInfoUpdate 
(266)
                                                            
criticality: reject 
(0)
                                                            
value
                                                                
SegmentInformationListIE-SystemInfoUpdate: 1 
item
                                                                    
Item 
0
                                                                        
SegmentInformationItem-SystemInfoUpdate
                                                                            
iB-SG-POS: 
0
                                                                            
segment-Type: complete-SIB 
(5)
                                                                            
iB-SG-DATA: 609104650004062120321101990C8D4400D01CA880E8 [bit length 
176]


So, my question is how is that done?  Can a higher level 
dissector be invoked via an ASN.1 dissector while returning back later to finish 
decoding the remaining IEs?  If so, where is an example I can follow?

Thanks,
Rick