Wireshark-bugs: [Wireshark-bugs] [Bug 7764] New: Access Point Name in GSM A-I/F DTAP - Activate

Date: Thu, 27 Sep 2012 11:33:39 -0700 (PDT)
https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=7764

           Summary: Access Point Name in GSM A-I/F DTAP - Activate PDP
                    Context Request not displayed correctly
           Product: Web sites
           Version: N/A
          Platform: x86
        OS/Version: Windows 7
            Status: NEW
          Severity: Normal
          Priority: Low
         Component: Main site - www.wireshark.org
        AssignedTo: bugzilla-admin@xxxxxxxxxxxxx
        ReportedBy: rgallant@xxxxxxxxxxx


Created attachment 9241
  --> https://bugs.wireshark.org/bugzilla/attachment.cgi?id=9241
GPRS DTAP ActivatePDPContext msg with bad APN display

Build Information:
Version 1.8.1 (SVN Rev 43946 from /trunk-1.8)
--


The message below is a NAS Activate PDP Context Request (ASCII packet
dissection export).

As part of the message, it uses an 'Access Point Name' (APN) value of 'BTS'.

In the decode detail panel, the APN is displayed like this:

    Access Point Name
        Element ID: 0x28
        Length: 3
        APN: TS 

That is, the first letter of BTS is missing.

However, it is encoded correctly as per 3GPP 24.008 in the packet data window
(lower panel) as:

byte 0x8d: Access point name IEI number            =  0x28 
byte 0x8e: Length of access point name contents    =  0x03
byte 0x8f: Letter B                                =  0x42
byte 0x90: Letter T                                =  0x54
byte 0x91: Letter S                                =  0x53


I have attached a single packet pcap file as reference.


------------------------------------------------------------------------

No.     Time        Source                Destination           Protocol Length
Info
   2809 150.673348  10.10.10.37           10.10.10.44           RANAP    288   
SACK (RUA) id-DirectTransfer (DTAP) (SM) Activate PDP Context Request 

Frame 2809: 288 bytes on wire (2304 bits), 288 bytes captured (2304 bits)
Linux cooked capture
Internet Protocol Version 4, Src: 10.10.10.37 (10.10.10.37), Dst: 10.10.10.44
(10.10.10.44)
Stream Control Transmission Protocol, Src Port: 14003 (14003), Dst Port: 14003
(14003)
UTRAN Iuh interface RUA signalling
Radio Access Network Application Part
GSM A-I/F DTAP - Activate PDP Context Request
    Protocol Discriminator: GPRS session management messages
    01.. .... = Sequence number: 1
    DTAP GPRS Session Management Message Type: Activate PDP Context Request
(0x41)
    Network Service Access Point Identifier - Requested NSAPI
    LLC Service Access Point Identifier - Requested LLC SAPI
    Quality Of Service - Requested QoS
    Packet Data Protocol Address - Requested PDP address
    Access Point Name
        Element ID: 0x28
        Length: 3
        APN: TS 
    Protocol Configuration Options

Frame (288 bytes):

0000  00 00 00 01 00 06 00 03 a2 05 1a 6d 00 00 08 00   ...........m....
0010  45 00 01 10 00 12 40 00 ff 84 51 f3 0a 0a 0a 25   [email protected]....%
0020  0a 0a 0a 2c 36 b3 36 b3 d2 e2 8e 08 d0 ce 29 f3   ...,6.6.......).
0030  03 00 00 10 d2 e2 8e 14 00 00 80 00 00 00 00 00   ................
0040  00 03 00 dd a6 eb 46 64 00 00 00 0b 00 00 00 13   ......Fd........
0050  00 02 40 80 c8 00 00 03 00 07 00 01 80 00 03 00   ..@.............
0060  03 00 00 00 00 04 00 80 b4 80 b2 00 14 40 80 ad   .............@..
0070  00 00 04 00 10 40 80 8a 80 88 0a 41 05 03 0b 00   [email protected]....
0080  00 00 00 00 00 00 00 04 00 00 02 01 21 28 03 42   ............!(.B
0090  54 53 27 6e 80 c2 23 23 01 01 00 23 10 ea 7e 0d   TS'n..##...#..~.
00a0  41 02 56 07 dd ac 0e a0 0c ac 44 23 e0 55 4d 54   A.V.......D#.UMT
00b0  53 5f 43 48 41 50 5f 53 52 56 52 c2 23 25 02 01   S_CHAP_SRVR.#%..
00c0  00 25 10 2d 57 79 75 f2 41 94 03 e6 19 3e 6c 42   .%.-Wyu.A....>lB
00d0  31 17 01 6c 6a 64 78 63 65 6a 61 62 64 67 63 73   1..ljdxcejabdgcs
00e0  6f 65 72 80 21 1c 01 00 00 1c 81 06 00 00 00 00   oer.!...........
00f0  82 06 00 00 00 00 83 06 00 00 00 00 84 06 00 00   ................
0100  00 00 00 0f 40 06 00 14 22 00 12 34 00 37 40 01   ....@..."..4.7@.
0110  56 00 3a 40 08 00 14 22 00 12 34 34 34 00 00 00   V.:@..."..444...

------------------------------------------------------------------------

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