add three tests for CIPHER MODE COMPLETE without algo

Add three tests which exercise MSC behaviour when a CIPHER MODE
COMPLETE command lacks the optional chosenEncryptionAlgorithm IE.
Check for behaviour with A5/1, A5/3, and A5/1 + A5/3 configured
in the network, and expect the location update to succeed.

These tests pass on master, but they should somehow verify the
cipher the MSC ends up using. I am not quite sure how to do that.
Would inspecting the MSC's VTY be a reasonable approach? How
could his be done by code which runs on BSC_ConnectionHandler?

Change-Id: I1a2a126795c544613a7a87e238e1fc8c4e943885
Related: OS#2872

library/BSSMAP_Templates.ttcn

@@ -1174,6 +1174,19 @@ modifies ts_BSSAP_BSSMAP := {
 	}
 }
 
+template PDU_BSSAP ts_BSSMAP_CipherModeComplAlg(template BSSMAP_IE_ChosenEncryptionAlgorithm chosenEncryptionAlgorithm := ?)
+modifies ts_BSSAP_BSSMAP := {
+	pdu := {
+		bssmap := {
+			cipherModeComplete := {
+				messageType := '55'O,
+				layer3MessageContents := omit,
+				chosenEncryptionAlgorithm := chosenEncryptionAlgorithm
+			}
+		}
+	}
+}
+
 template PDU_BSSAP tr_BSSMAP_CipherModeCompl(template OCT1 alg := ?) modifies tr_BSSAP_BSSMAP := {
 	pdu := {
 		bssmap := {

msc/BSC_ConnectionHandler.ttcn

@@ -494,12 +494,25 @@ runs on BSC_ConnHdlr {
 	}
 
 	f_mm_common();
+	f_msc_lu_hlr();
+	f_accept_reject_lu();
+	/* FIXME: there could be pending SMS or other common procedures by the MSC, let's ignore them */
+	f_expect_clear();
+
+	setverdict(pass);
+}
 
+function f_msc_lu_hlr() runs on BSC_ConnHdlr
+{
 	/* Expect MSC to perform LU with HLR */
 	GSUP.receive(tr_GSUP_UL_REQ(g_pars.imsi));
 	GSUP.send(ts_GSUP_ISD_REQ(g_pars.imsi, g_pars.msisdn));
 	GSUP.receive(tr_GSUP_ISD_RES(g_pars.imsi));
 	GSUP.send(ts_GSUP_UL_RES(g_pars.imsi));
+}
+
+function f_accept_reject_lu() runs on BSC_ConnHdlr {
+	var PDU_DTAP_MT dtap_mt;
 
 	alt {
 	[] BSSAP.receive(tr_PDU_DTAP_MT(tr_ML3_MT_LU_Acc)) -> value dtap_mt {
@@ -529,9 +542,6 @@ runs on BSC_ConnHdlr {
 
 	/* Wait for MM-Information (if enabled) */
 	f_expect_mm_info();
-
-	/* FIXME: there could be pending SMS or other common procedures by the MSC, let's ignore them */
-	f_expect_clear();
 	setverdict(pass);
 }
 

msc/MSC_Tests.cfg

@@ -61,3 +61,6 @@ MSC_Tests.control
 #MSC_Tests.TC_reset_two
 #MSC_Tests.TC_lu_and_mt_call
 #MSC_Tests.TC_cipher_complete_with_invalid_cipher
+#MSC_Tests.TC_cipher_complete_1_without_cipher
+#MSC_Tests.TC_cipher_complete_3_without_cipher
+#MSC_Tests.TC_cipher_complete_13_without_cipher

msc/MSC_Tests.ttcn

@@ -3647,6 +3647,94 @@ testcase TC_lu_with_invalid_mcc_mnc() runs on MTC_CT {
 	vc_conn.done;
 }
 
+private function f_tc_cipher_complete_without_alg(charstring id, BSC_ConnHdlrPars pars, octetstring kc_support) runs on BSC_ConnHdlr {
+	pars.net.expect_auth := true;
+	pars.net.expect_ciph := true;
+	pars.net.kc_support := kc_support;
+	f_init_handler(pars);
+
+	g_pars.vec := f_gen_auth_vec_2g();
+
+	/* Can't use f_perform_lu() directly. Code below is based on it. */
+
+	/* tell GSUP dispatcher to send this IMSI to us */
+	f_create_gsup_expect(hex2str(g_pars.imsi));
+
+	/* Send BSSAP_Conn_Req with COMPL L3 INFO to MSC */
+	var PDU_ML3_MS_NW l3_lu := f_build_lu_imsi(g_pars.imsi)
+	f_cl3_or_initial_ue(l3_lu);
+
+	f_mm_auth();
+
+	var OCT1 a5_net := f_alg_mask_from_cm(g_pars.cm2);
+	var OCT1 a5_intersect := g_pars.net.kc_support and4b a5_net;
+	alt {
+	[] BSSAP.receive(tr_BSSMAP_CipherModeCmd(a5_intersect, g_pars.vec.kc)) {
+		BSSAP.send(ts_BSSMAP_CipherModeComplAlg(omit));
+		}
+	[] BSSAP.receive(tr_BSSMAP_ClassmarkReq) {
+		BSSAP.send(ts_BSSMAP_ClassmarkUpd(g_pars.cm2, g_pars.cm3));
+		repeat;
+		}
+	[] BSSAP.receive(tr_BSSMAP_CipherModeCmd(?, g_pars.vec.kc)) {
+		setverdict(fail, "Wrong ciphering algorithm mask in CiphModCmd");
+		mtc.stop;
+		}
+	[] BSSAP.receive {
+		setverdict(fail, "Unknown/unexpected BSSAP received");
+		mtc.stop;
+		}
+	}
+
+	/* TODO: Verify MSC is using the best cipher available! How? */
+
+	f_msc_lu_hlr();
+	f_accept_reject_lu();
+	f_expect_clear();
+	setverdict(pass);
+}
+
+/* A5/1 only permitted on network side; attempt CIPHER MODE COMPLETE without specifying the accepted algorithm. */
+private function f_tc_cipher_complete_1_without_cipher(charstring id, BSC_ConnHdlrPars pars) runs on BSC_ConnHdlr {
+	f_tc_cipher_complete_without_alg(id, pars, '02'O /* A5/1 only */);
+}
+
+/* A5/3 only permitted on network side; attempt CIPHER MODE COMPLETE without specifying the accepted algorithm. */
+private function f_tc_cipher_complete_3_without_cipher(charstring id, BSC_ConnHdlrPars pars) runs on BSC_ConnHdlr {
+	f_tc_cipher_complete_without_alg(id, pars, '08'O /* A5/3 only */);
+}
+
+/* A5/1 + A5/3 permitted on network side; attempt CIPHER MODE COMPLETE without specifying the accepted algorithm. */
+private function f_tc_cipher_complete_13_without_cipher(charstring id, BSC_ConnHdlrPars pars) runs on BSC_ConnHdlr {
+	f_tc_cipher_complete_without_alg(id, pars, '0A'O /* A5/1 and A5/3 enabled */);
+}
+
+testcase TC_cipher_complete_1_without_cipher() runs on MTC_CT {
+	var BSC_ConnHdlr vc_conn;
+	f_init();
+	f_vty_config(MSCVTY, "network", "encryption a5 1");
+
+	vc_conn := f_start_handler(refers(f_tc_cipher_complete_1_without_cipher), 53);
+	vc_conn.done;
+}
+
+testcase TC_cipher_complete_3_without_cipher() runs on MTC_CT {
+	var BSC_ConnHdlr vc_conn;
+	f_init();
+	f_vty_config(MSCVTY, "network", "encryption a5 3");
+
+	vc_conn := f_start_handler(refers(f_tc_cipher_complete_3_without_cipher), 54);
+	vc_conn.done;
+}
+
+testcase TC_cipher_complete_13_without_cipher() runs on MTC_CT {
+	var BSC_ConnHdlr vc_conn;
+	f_init();
+	f_vty_config(MSCVTY, "network", "encryption a5 1 3");
+
+	vc_conn := f_start_handler(refers(f_tc_cipher_complete_13_without_cipher), 55);
+	vc_conn.done;
+}
 
 /* TODO (SMS):
    * different user data lengths
@@ -5316,6 +5404,9 @@ control {
 	execute( TC_lu_and_ss_session_timeout() );
 
 	execute( TC_cipher_complete_with_invalid_cipher() );
+	execute( TC_cipher_complete_1_without_cipher() );
+	execute( TC_cipher_complete_3_without_cipher() );
+	execute( TC_cipher_complete_13_without_cipher() );
 	execute( TC_lu_with_invalid_mcc_mnc() );
 
 	execute( TC_sgsap_reset() );