Wireshark-bugs: [Wireshark-bugs] [Bug 8004] Incorrect Decoding for TCAP Abort

Date: Wed, 21 Nov 2012 01:31:18 -0800 (PST)
https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=8004

--- Comment #3 from Vineeth <vineethvijaysv@xxxxxxxxx> 2012-11-21 01:31:17 PST ---
(In reply to comment #2)
> It looks to me like there is
> Frame 1
> Transaction Capabilities Application Part
> 
> 0000   67 2c 49 04 28 0d 00 01 6b 24 28 22 06 07 00 11  g,I.(...k$("....
> 0010   86 05 01 01 01 a0 17 64 15 80 01 00 be 10 28 0e  .......d......(.
> 0020   06 07 04 00 00 01 01 01 01 a0 03 a4 01 80        ..............
> 
> The last byte 0x80 is map-userAbort (CHOICE tag 4) 
> 
> MAP-DialoguePDU ::= CHOICE {
>     map-open        [0] MAP-OpenInfo,
>     map-accept    [1] MAP-AcceptInfo,
>     map-close        [2] MAP-CloseInfo,
>     map-refuse    [3] MAP-RefuseInfo,
>     map-userAbort    [4] MAP-UserAbortInfo,
>     map-providerAbort    [5] MAP-ProviderAbortInfo}
> 
> MAP-UserAbortInfo is missing from the buffer.


I think the packet is complete. Its last 5 digit should be decoded as:

0xa0 -> MAP-Dialogue-PDU
0x03 -> length: 3 bytes
0xa4 -> map-UserAbortInfo
0x01 -> length: 1 byte
0x80 -> userSpecificReason

The decode itself is happening fine if following changes are made in
packet-ber.c, but the residual buffer (which doesn't exist) is attempted to be
decoded as GSM-MAP decoder, and an exception for packet limitation occurs :(

@@ -1147,7 +1146,7 @@
         THROW(ReportedBoundsError);
     }

-    oct = (tvb_length(tvb) == 1)?0:tvb_get_guint8(tvb, offset);
+    oct = tvb_get_guint8(tvb, offset);
     offset += 1;

     if(!(oct&0x80)) {

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