library/RSL: pass lost link event to upper layers instead of failing

Some tests may expect that behavior so let the test decide what to do
with it.

Change-Id: Idd4bdfc99514f4c439837f0ce4a20ec5ff45e86c
diff --git a/library/RSL_Emulation.ttcn b/library/RSL_Emulation.ttcn
index 66cc4dc..2fcb96c 100644
--- a/library/RSL_Emulation.ttcn
+++ b/library/RSL_Emulation.ttcn
@@ -394,6 +394,20 @@
 	return f_streamId_by_trx(trx_nr);
 }
 
+private function f_trx_conn_map_unregister(integer conn_id)
+runs on RSL_Emulation_CT return IpaStreamId {
+
+	for (var integer i := 0; i < sizeof(TrxConnMap); i := i + 1) {
+		if (conn_id == TrxConnMap[i]) {
+			TrxConnMap[i] := -1;
+			TrxConnNum := TrxConnNum - 1;
+			return f_streamId_by_trx(i);
+		}
+	}
+
+	testcase.stop("Trying to unregister an unknown conn_id=", conn_id);
+}
+
 private function f_trx_conn_map_resolve(IpaStreamId id)
 runs on RSL_Emulation_CT return integer {
 	var integer trx_nr := f_trx_by_streamId(id);
@@ -498,12 +512,17 @@
 			/* Notify the upper layers about a new connection */
 			CCHAN_PT.send(ts_RSLEm_EV(RSLEM_EV_TRX_UP, sid));
 			}
-		[bts_role] IPA_PT.receive(tr_ASP_IPA_EV(ASP_IPA_EVENT_DOWN)) {
-			Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail, "Lost IPA connection!");
-
+		[bts_role] IPA_PT.receive(tr_ASP_IPA_EV(ASP_IPA_EVENT_DOWN)) -> value evt {
+			log("Lost IPA connection! (conn_id=", evt.conn_id, "): ", evt.id_resp);
+			/* Notify the upper layers about lost connection */
+			var IpaStreamId sid := f_trx_conn_map_unregister(evt.conn_id);
+			CCHAN_PT.send(ts_RSLEm_EV(RSLEM_EV_TRX_DOWN, sid));
 			}
-		[not bts_role] IPA_PT.receive(tr_ASP_IPA_EV(ASP_IPA_EVENT_DOWN)) {
-			Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail, "Lost IPA connection!");
+		[not bts_role] IPA_PT.receive(tr_ASP_IPA_EV(ASP_IPA_EVENT_DOWN)) -> value evt {
+			log("Lost IPA connection! (conn_id=", evt.conn_id, ")");
+			/* Notify the upper layers about lost connection */
+			var IpaStreamId sid := f_trx_conn_map_unregister(evt.conn_id);
+			CCHAN_PT.send(ts_RSLEm_EV(RSLEM_EV_TRX_DOWN, sid));
 			}
 		[bts_role] IPA_PT.receive(tr_ASP_IPA_EV(ASP_IPA_EVENT_ID_ACK)) {
 			IPA_PT.send(ts_ASP_RSL_UD(ts_RSL_PAGING_LOAD_IND(23)));