Change in ...osmo-ttcn3-hacks[master]: sgsn: new test for N(U) = 0 in GMM ID response

[osmith]

osmith has uploaded this change for review. ( https://gerrit.osmocom.org/c/osmo-ttcn3-hacks/+/14516


Change subject: sgsn: new test for N(U) = 0 in GMM ID response
......................................................................

sgsn: new test for N(U) = 0 in GMM ID response

Related: OS#2951
Change-Id: I19939892d6a49f80453de977021892ba02d3bed2
---
M sgsn/SGSN_Tests.ttcn
1 file changed, 39 insertions(+), 5 deletions(-)



  git pull ssh://gerrit.osmocom.org:29418/osmo-ttcn3-hacks refs/changes/16/14516/1

diff --git a/sgsn/SGSN_Tests.ttcn b/sgsn/SGSN_Tests.ttcn
index 03c9d05..b8b2d29 100644
--- a/sgsn/SGSN_Tests.ttcn
+++ b/sgsn/SGSN_Tests.ttcn
@@ -392,23 +392,26 @@
 	BSSGP[gb_index].send(ts_BSSGP_UL_UD(g_pars.tlli, g_pars.bssgp_cell_id[gb_index], llc_enc));
 }
 
-function f_send_l3_gmm_llc(template PDU_L3_MS_SGSN l3_mo, integer gb_index := 0) runs on BSSGP_ConnHdlr {
+function f_send_l3_gmm_llc(template PDU_L3_MS_SGSN l3_mo, integer gb_index := 0, integer n_u := -1) runs on BSSGP_ConnHdlr {
 	var octetstring l3_enc := enc_PDU_L3_MS_SGSN(valueof(l3_mo));
 	var BIT4 sapi := f_llc_sapi_by_l3_mo(valueof(l3_mo));
-	var integer n_u := f_llc_get_n_u_tx(llc[bit2int(sapi)]);
+
+	if (n_u == -1) {
+		n_u := f_llc_get_n_u_tx(llc[bit2int(sapi)]);
+	}
 	f_send_llc(ts_LLC_UI(l3_enc, sapi, '0'B, n_u), gb_index);
 }
 
-altstep as_mm_identity(integer gb_idx := 0) runs on BSSGP_ConnHdlr {
+altstep as_mm_identity(integer gb_idx := 0, integer n_u := -1) runs on BSSGP_ConnHdlr {
 	var MobileL3_CommonIE_Types.MobileIdentityLV mi;
 	[] BSSGP[gb_idx].receive(tr_BD_L3_MT(tr_GMM_ID_REQ('001'B))) {
 		mi := valueof(ts_MI_IMSI_LV(g_pars.imsi));
-		f_send_l3_gmm_llc(ts_GMM_ID_RESP(mi), gb_idx);
+		f_send_l3_gmm_llc(ts_GMM_ID_RESP(mi), gb_idx, n_u);
 		repeat;
 	}
 	[] BSSGP[gb_idx].receive(tr_BD_L3_MT(tr_GMM_ID_REQ('010'B))) {
 		mi := valueof(ts_MI_IMEI_LV(g_pars.imei));
-		f_send_l3_gmm_llc(ts_GMM_ID_RESP(mi), gb_idx);
+		f_send_l3_gmm_llc(ts_GMM_ID_RESP(mi), gb_idx, n_u);
 		repeat;
 	}
 }
@@ -2447,6 +2450,36 @@
 	vc_conn.done;
 }
 
+/* Attach reject after sending two ML L3 messages with N(U) set to zero (OS#2951) */
+private function f_TC_attach_pdp_resp_nu_0(charstring id) runs on BSSGP_ConnHdlr {
+	var RoutingAreaIdentificationV old_ra := f_random_RAI();
+
+	f_send_l3_gmm_llc(ts_GMM_ATTACH_REQ(f_mi_get_lv(), old_ra, false, false, omit, omit), n_u := 0);
+
+	alt {
+	[] as_mm_identity(n_u := 0);
+	/* FIXME: sgsn ignores the wrong N(U) two times, and then "learns" the one we are using. Is this what we want?
+         *        if this test gets used, count the ID REQs we get from sgsn, and add verdicts here. */
+	}
+}
+testcase TC_attach_pdp_resp_nu_0() runs on test_CT {
+	/* MS  -> SGSN: Attach Request, with N(U) = 0
+	 * MS <-  SGSN: Identity Request
+	 * MS  -> SGSN: Identity Response, with N(U) = 0 (broken behavior!)
+	 *		(SGSN drops the message due to invalid N(U))
+	 * MS <-  SGSN: Identity Request (2nd try)
+	 * MS  -> SGSN: Identity Response, with N(U) = 0 (broken behavior!)
+	 *		(SGSN drops the message due to invalid N(U))
+	 * MS <-  SGSN: Identity Request (3rd try)
+	 * MS  -> SGSN: Identity Response, with N(U) = 0 (broken behavior!)
+	 *		(SGSN does recovery handling and accepts the message)
+	 * MS <-  SGSN: Attach Reject (Network Failure)
+	 *		(SGSN requests subscriber auth info from HLR, but HLR does not answer in this test) */
+	var BSSGP_ConnHdlr vc_conn;
+	f_init();
+	vc_conn := f_start_handler(refers(f_TC_attach_pdp_resp_nu_0), testcasename(), g_gb, 2, 40.0);
+	vc_conn.done;
+}
 
 control {
 	execute( TC_attach() );
@@ -2502,6 +2535,7 @@
 	execute( TC_llc_null() );
 	execute( TC_llc_sabm_dm_llgmm() );
 	execute( TC_llc_sabm_dm_ll5() );
+	execute( TC_attach_pdp_resp_nu_0() );
 }
 
 

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Gerrit-Project: osmo-ttcn3-hacks
Gerrit-Branch: master
Gerrit-Change-Id: I19939892d6a49f80453de977021892ba02d3bed2
Gerrit-Change-Number: 14516
Gerrit-PatchSet: 1
Gerrit-Owner: osmith <osmith at sysmocom.de>
Gerrit-MessageType: newchange
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