From 654f85e2b85c3a5b18be8904d1602b98df3c0ae0 Mon Sep 17 00:00:00 2001
From: Daniel Willmann <dwillmann@sysmocom.de>
Date: Mon, 12 Oct 2020 18:10:06 +0200
Subject: Correctly handle ALIVE/TEST procedure with FR/NS-over-IP without SNS

If IP-SNS is not used we should wait for the RESET procedure to finish
before sending NS-ALIVE.
For IP-SNS start NS-ALIVE in both roles (sgsn and bss) and don't handle
NS-RESET.

Also unified the log messages a bit (received -> Rx).

Related: SYS#5002
Change-Id: Ie01fee70297255b3d9c091bc2cec75b0f915c588
---
 library/NS_Emulation.ttcnpp | 57 +++++++++++++++++++++++++++++----------------
 1 file changed, 37 insertions(+), 20 deletions(-)

diff --git a/library/NS_Emulation.ttcnpp b/library/NS_Emulation.ttcnpp
index 5fb2aa67..4d3db4cd 100644
--- a/library/NS_Emulation.ttcnpp
+++ b/library/NS_Emulation.ttcnpp
@@ -217,20 +217,9 @@ module NS_Emulation {
 			f_sendAlive();
 		}
 
-		[config.role_sgsn] NSCP.receive(NS_Provider_Evt:{link_status:=NS_PROV_LINK_STATUS_UP}) {
-			log("Provider Link came up: sending NS-ALIVE");
-			f_sendAlive();
-			Tns_test.start;
-			}
-
-		[not config.role_sgsn] NSCP.receive(NS_Provider_Evt:{link_status:=NS_PROV_LINK_STATUS_UP}) {
-			log("Provider Link came up: sending NS-RESET");
-			f_sendReset();
-			}
-
 		/* Stop t_alive when receiving ALIVE-ACK */
 		[Tns_alive.running] NSCP.receive(t_NS_ALIVE_ACK) {
-			log("NS-ALIVE-ACK received: stopping Tns-alive; starting Tns-test");
+			log("Rx NS-ALIVE-ACK: stopping Tns-alive; starting Tns-test");
 			Tns_alive.stop;
 			Tns_test.start;
 		}
@@ -246,10 +235,36 @@ module NS_Emulation {
 			/* FIXME */
 		}
 
+		[not config.handle_sns] as_handle_reset();
+
+		[config.role_sgsn and config.handle_sns and ischosen(config.provider.ip)] as_sns_sgsn();
+
+		/* default case of handling unknown PDUs */
+		[] NSCP.receive(PDU_NS: ?) -> value rf {
+			log("Rx Unexpected NS PDU ", rf," in state ", g_state);
+			NSCP.send(ts_NS_STATUS(NS_CAUSE_PDU_NOT_COMPATIBLE_WITH_PROTOCOL_STATE, rf));
+		}
+	}
+
+	private altstep as_handle_reset() runs on NS_CT {
+		var PDU_NS rf;
+
+		[config.role_sgsn] NSCP.receive(NS_Provider_Evt:{link_status:=NS_PROV_LINK_STATUS_UP}) {
+			log("Provider Link came up: waiting for NS-RESET");
+			}
+
+		[not config.role_sgsn] NSCP.receive(NS_Provider_Evt:{link_status:=NS_PROV_LINK_STATUS_UP}) {
+			log("Provider Link came up: sending NS-RESET");
+			f_sendReset();
+			}
+
 		/* Respond to RESET with correct NSEI/NSVCI */
 		[] NSCP.receive(tr_NS_RESET(?, config.nsvci, config.nsei)) -> value rf {
 			f_change_state(NSE_S_ALIVE_BLOCKED);
 			NSCP.send(ts_NS_RESET_ACK(config.nsvci, config.nsei));
+			log("Rx NS-RESET: Sending NS-ALIVE");
+			f_sendAlive();
+			Tns_test.start;
 		}
 
 		/* Respond to RESET with wrong NSEI/NSVCI */
@@ -257,20 +272,22 @@ module NS_Emulation {
 			log("Rx NS-RESET for unknown NSEI/NSVCI");
 			/* FIXME */
 		}
-
-		[config.role_sgsn and config.handle_sns and ischosen(config.provider.ip)] as_sns_sgsn();
-
-		/* default case of handling unknown PDUs */
-		[] NSCP.receive(PDU_NS: ?) -> value rf {
-			log("Rx Unexpected NS PDU ", rf," in state ", g_state);
-			NSCP.send(ts_NS_STATUS(NS_CAUSE_PDU_NOT_COMPATIBLE_WITH_PROTOCOL_STATE, rf));
-		}
 	}
 
 	/* simple IP Sub-Network Service responder for the SGSN side. This is not a full implementation
 	 * of the protocol, merely sufficient to make the PCU/BSS side happy to proceed */
 	private altstep as_sns_sgsn() runs on NS_CT {
 		var PDU_NS rf;
+		[config.role_sgsn] NSCP.receive(NS_Provider_Evt:{link_status:=NS_PROV_LINK_STATUS_UP}) {
+			log("Provider Link came up: sending NS-ALIVE");
+			f_sendAlive();
+			}
+
+		[not config.role_sgsn] NSCP.receive(NS_Provider_Evt:{link_status:=NS_PROV_LINK_STATUS_UP}) {
+			log("Provider Link came up: sending NS-ALIVE");
+			f_sendAlive();
+			}
+
 		[] NSCP.receive(tr_SNS_SIZE(config.nsei)) -> value rf {
 			/* blindly acknowledge whatever the PCU sends */
 			NSCP.send(ts_SNS_SIZE_ACK(config.nsei, omit));
-- 
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