utils.py: Add helper method to parse ePDG Selection info TLV
ePDG selection information TLV data object is made of following elements:
ePDG Selection Information Tag '80' (1 Byte)
Length 5n Note
PLMN 1 (3 Bytes)
ePDG Priority (2 Bytes)
ePDG FQDN format '00' or '01' (1 Byte)
...
PLMN n
...
Note: The length is coded according to ISO/IEC 8825-1 [35]
Note 2: Inconsistency in spec: 3GPP TS 31.102 version 15.2.0 Release 15, 4.2.104
As per spec, Length field value is 5n, where n is number of PLMNs
But, each PLMN entry is made of PLMN (3 Bytes) + ePDG Priority (2 Bytes) + ePDG FQDN format (1 Byte)
Totalling to 6 Bytes, maybe Length should be 6n and not 5n
Change-Id: I0f9f38961a589e3f9a53d2288a3dc6fa71a4b1b0
diff --git a/pySim/utils.py b/pySim/utils.py
index f7d099b..a3e4cb1 100644
--- a/pySim/utils.py
+++ b/pySim/utils.py
@@ -609,3 +609,57 @@
sl = SerialSimLink(device=opts.device, baudrate=opts.baudrate)
return sl
+
+def dec_ePDGSelection(sixhexbytes):
+ """
+ Decode ePDGSelection to get EF.ePDGSelection or EF.ePDGSelectionEm.
+ See 3GPP TS 31.102 version 15.2.0 Release 15, section 4.2.104 and 4.2.106.
+ """
+
+ res = {'mcc': 0, 'mnc': 0, 'epdg_priority': 0, 'epdg_fqdn_format': ''}
+ plmn_chars = 6
+ epdg_priority_chars = 4
+ epdg_fqdn_format_chars = 2
+ # first three bytes (six ascii hex chars)
+ plmn_str = sixhexbytes[:plmn_chars]
+ # two bytes after first three bytes
+ epdg_priority_str = sixhexbytes[plmn_chars:plmn_chars + epdg_priority_chars]
+ # one byte after first five bytes
+ epdg_fqdn_format_str = sixhexbytes[plmn_chars + epdg_priority_chars:plmn_chars + epdg_priority_chars + epdg_fqdn_format_chars]
+ res['mcc'] = dec_mcc_from_plmn(plmn_str)
+ res['mnc'] = dec_mnc_from_plmn(plmn_str)
+ res['epdg_priority'] = epdg_priority_str
+ res['epdg_fqdn_format'] = epdg_fqdn_format_str == '00' and 'Operator Identifier FQDN' or 'Location based FQDN'
+ return res
+
+def format_ePDGSelection(hexstr):
+ ePDGSelection_info_tag_chars = 2
+ ePDGSelection_info_tag_str = hexstr[:2]
+ # Minimum length
+ len_chars = 2
+ # TODO: Need to determine length properly - definite length support only
+ # Inconsistency in spec: 3GPP TS 31.102 version 15.2.0 Release 15, 4.2.104
+ # As per spec, length is 5n, n - number of PLMNs
+ # But, each PLMN entry is made of PLMN (3 Bytes) + ePDG Priority (2 Bytes) + ePDG FQDN format (1 Byte)
+ # Totalling to 6 Bytes, maybe length should be 6n
+ len_str = hexstr[ePDGSelection_info_tag_chars:ePDGSelection_info_tag_chars+len_chars]
+ if len_str[0] == '8':
+ # The bits 7 to 1 denotes the number of length octets if length > 127
+ if int(len_str[1]) > 0:
+ # Update number of length octets
+ len_chars = len_chars * int(len_str[1])
+ len_str = hexstr[ePDGSelection_info_tag_chars:len_chars]
+
+ content_str = hexstr[ePDGSelection_info_tag_chars+len_chars:]
+ # Right pad to prevent index out of range - multiple of 6 bytes
+ content_str = rpad(content_str, len(content_str) + (12 - (len(content_str) % 12)))
+ s = ""
+ for rec_data in hexstr_to_Nbytearr(content_str, 6):
+ rec_info = dec_ePDGSelection(rec_data)
+ if rec_info['mcc'] == 0xFFF and rec_info['mnc'] == 0xFFF:
+ rec_str = "unused"
+ else:
+ rec_str = "MCC: %03d MNC: %03d ePDG Priority: %s ePDG FQDN format: %s" % \
+ (rec_info['mcc'], rec_info['mnc'], rec_info['epdg_priority'], rec_info['epdg_fqdn_format'])
+ s += "\t%s # %s\n" % (rec_data, rec_str)
+ return s