Wireshark-bugs: [Wireshark-bugs] [Bug 7952] Decoding of ECGI

Date: Fri, 2 Nov 2012 08:59:46 -0700 (PDT)
https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=7952

--- Comment #3 from Anders Broman <anders.broman@xxxxxxxxxxxx> 2012-11-02 08:59:45 PDT ---
Well there is two encoding possibillities:
/*
 * MCC/MNC dissection - little endian MNC encoding
 *
:
 * MNC of length 3:
 *
 *   8   7   6   5   4   3   2   1
 * +---+---+---+---+---+---+---+---+
 * |  MCC digit 2  |  MCC digit 1  |  octet x
 * +---------------+---------------+
 * |  MNC digit 3  |  MCC digit 3  |  octet x+1
 * +---------------+---------------+
 * |  MNC digit 2  |  MNC digit 1  |  octet x+2
 * +---------------+---------------+
 *
 *
 * MCC/MNC dissection - big endian MNC encoding
:
 * MNC of length 3:
 *
 *   8   7   6   5   4   3   2   1
 * +---+---+---+---+---+---+---+---+
 * |  MCC digit 2  |  MCC digit 1  |  octet x
 * +---------------+---------------+
 * |  MNC digit 1  |  MCC digit 3  |  octet x+1
 * +---------------+---------------+
 * |  MNC digit 3  |  MNC digit 2  |  octet x+2
 * +---------------+---------------+
 */

3GPP TS 29.171 version 10.3.0 Release 10
7.4.27 PLMN Identity
- digits 0 to 9, encoded
0000 to 1001,
- 1111 used as filler digit,
two digits per octet,
- bits 4 to 1 of octet n
encoding digit 2n-1
- bits 8 to 5 of octet n
encoding digit 2n
-The Selected PLMN
identity consists of 3 digits
from MCC followed by
either
-a filler digit plus 2 digits
from MNC (in case of 2
digit MNC) or
-3 digits from MNC (in case
of a 3 digit MNC).

to me it's not totaly clear which encoding method should be used but I suppose
one could assume  MCC/MNC dissection - little endian MNC encoding, as the
filler is supposed to come after MCC and the filler should probably be the last
digit.
If so there is a bug in Wireshark:
- dissect_e212_mcc_mnc(parameter_tvb, actx->pinfo, tree, 0, FALSE);
+ dissect_e212_mcc_mnc(parameter_tvb, actx->pinfo, tree, 0, TRUE);

/Anders

-- 
Configure bugmail: https://bugs.wireshark.org/bugzilla/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are watching all bug changes.