From 851e9c0f4c92f2336faa5f5b9b4e3aa7c963608e Mon Sep 17 00:00:00 2001
From: Daniel Laszlo Sitzer <dlsitzer@gmail.com>
Date: Tue, 4 Dec 2018 19:40:08 +0100
Subject: utils: add EF [H|O]PLMNwAcT decoding.

Allow decoding and pretty printing of PLMNwAcT, HPLMNwAcT and OPLMNwAct.

Includes unit tests for the added functions.

Change-Id: I9b8ca6ffd98f665690b84239d9a228e2c72c6ff9
---
 pySim/utils.py | 73 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 73 insertions(+)

(limited to 'pySim/utils.py')

diff --git a/pySim/utils.py b/pySim/utils.py
index ba94702..65f10c5 100644
--- a/pySim/utils.py
+++ b/pySim/utils.py
@@ -113,6 +113,79 @@ def enc_spn(name, hplmn_disp=False, oplmn_disp=False):
 	if oplmn_disp: byte1 = byte1|0x02
 	return i2h([byte1])+s2h(name)
 
+def hexstr_to_fivebytearr(s):
+	return [s[i:i+10] for i in range(0, len(s), 10) ]
+
+# Accepts hex string representing three bytes
+def dec_mcc_from_plmn(plmn):
+	ia = h2i(plmn)
+	digit1 = ia[0] & 0x0F		# 1st byte, LSB
+	digit2 = (ia[0] & 0xF0) >> 4	# 1st byte, MSB
+	digit3 = ia[1] & 0x0F		# 2nd byte, LSB
+	if digit3 == 0xF and digit2 == 0xF and digit1 == 0xF:
+		return 0xFFF # 4095
+	mcc = digit1 * 100
+	mcc += digit2 * 10
+	mcc += digit3
+	return mcc
+
+def dec_mnc_from_plmn(plmn):
+	ia = h2i(plmn)
+	digit1 = ia[2] & 0x0F		# 3rd byte, LSB
+	digit2 = (ia[2] & 0xF0) >> 4	# 3rd byte, MSB
+	digit3 = (ia[1] & 0xF0) >> 4	# 2nd byte, MSB
+	if digit3 == 0xF and digit2 == 0xF and digit1 == 0xF:
+		return 0xFFF # 4095
+	mnc = 0
+	# signifies two digit MNC
+	if digit3 == 0xF:
+		mnc += digit1 * 10
+		mnc += digit2
+	else:
+		mnc += digit1 * 100
+		mnc += digit2 * 10
+		mnc += digit3
+	return mnc
+
+def dec_act(twohexbytes):
+	act_list = [
+		{'bit': 15, 'name': "UTRAN"},
+		{'bit': 14, 'name': "E-UTRAN"},
+		{'bit':  7, 'name': "GSM"},
+		{'bit':  6, 'name': "GSM COMPACT"},
+		{'bit':  5, 'name': "cdma2000 HRPD"},
+		{'bit':  4, 'name': "cdma2000 1xRTT"},
+	]
+	ia = h2i(twohexbytes)
+	u16t = (ia[0] << 8)|ia[1]
+	sel = []
+	for a in act_list:
+		if u16t & (1 << a['bit']):
+			sel.append(a['name'])
+	return sel
+
+def dec_xplmn_w_act(fivehexbytes):
+	res = {'mcc': 0, 'mnc': 0, 'act': []}
+	plmn_chars = 6
+	act_chars = 4
+	plmn_str = fivehexbytes[:plmn_chars]				# first three bytes (six ascii hex chars)
+	act_str = fivehexbytes[plmn_chars:plmn_chars + act_chars]	# two bytes after first three bytes
+	res['mcc'] = dec_mcc_from_plmn(plmn_str)
+	res['mnc'] = dec_mnc_from_plmn(plmn_str)
+	res['act'] = dec_act(act_str)
+	return res
+
+def format_xplmn_w_act(hexstr):
+	s = ""
+	for rec_data in hexstr_to_fivebytearr(hexstr):
+		rec_info = dec_xplmn_w_act(rec_data)
+		if rec_info['mcc'] == 0xFFF and rec_info['mnc'] == 0xFFF:
+			rec_str = "unused"
+		else:
+			rec_str = "MCC: %3s MNC: %3s AcT: %s" % (rec_info['mcc'], rec_info['mnc'], ", ".join(rec_info['act']))
+		s += "\t%s # %s\n" % (rec_data, rec_str)
+	return s
+
 def derive_milenage_opc(ki_hex, op_hex):
 	"""
 	Run the milenage algorithm to calculate OPC from Ki and OP
-- 
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