sysmo-usim-sjs1: update EF.AD with correct MNC length

At the moment EF.AD, which contains the length of the MNC is not
updated. For two digit MNC (the usual case) this is fine since the
length is set to 2 by default. However, when one wants to set an MNC
with 3 digit length the file must be updated, otherwise the third digit
of the MNC is recognized as part of the MSIN.

Change-Id: I827092b2c7f7952f54b2d9f8dbda419a0dbfaf65
Related: OS#3850

pySim-read.py

@@ -176,5 +176,12 @@ if __name__ == '__main__':
 	except Exception as e:
 		print "MSISDN: Can't read file -- " + str(e)
 
+	# EF.AD
+	(res, sw) = scc.read_binary(['3f00', '7f20', '6fad'])
+	if sw == '9000':
+		print("AD: %s" % (res,))
+	else:
+		print("AD: Can't read, response code = %s" % (sw,))
+
 	# Done for this card and maybe for everything ?
 	print "Done !\n"

pySim/cards.py

@@ -118,6 +118,20 @@ class Card(object):
 		data, sw = self._scc.update_record(EF['SMSP'], 1, rpad(smsp, 84))
 		return sw
 
+	def update_ad(self, mnc):
+                #See also: 3GPP TS 31.102, chapter 4.2.18
+                mnclen = len(str(mnc))
+                if mnclen == 1:
+                        mnclen = 2
+                if mnclen > 3:
+			raise RuntimeError('unable to calculate proper mnclen')
+
+	        data = self._scc.read_binary(EF['AD'], length=None, offset=0)
+                size = len(data[0])/2
+                content = data[0][0:6] + "%02X" % mnclen
+		data, sw = self._scc.update_binary(EF['AD'], content)
+		return sw
+
 	def read_spn(self):
 		(spn, sw) = self._scc.read_binary(EF['SPN'])
 		if sw == '9000':
@@ -593,6 +607,11 @@ class SysmoUSIMSJS1(Card):
 			if sw != '9000':
 				print("Programming OPLMNwAcT failed with code %s"%sw)
 
+                # EF.AD
+                if p.get('mcc') and p.get('mnc'):
+			sw = self.update_ad(p['mnc'])
+			if sw != '9000':
+				print("Programming AD failed with code %s"%sw)
 
 		# EF.SMSP
 		r = self._scc.select_file(['3f00', '7f10'])