[M] Change in osmo-ttcn3-hacks[master]: SGsAP_Emulation: Introduce proper support for server-mode

15 Sep 2025

pespin has submitted this change. ( https://gerrit.osmocom.org/c/osmo-ttcn3-hacks/+/41083?usp=email )
Change subject: SGsAP_Emulation: Introduce proper support for server-mode
......................................................................
SGsAP_Emulation: Introduce proper support for server-mode
Prior to this commit, only initial (not really useful) SCTP server-mode
support existed in SGsAP_Emulation.
This is basically because MSC_Tests uses the SCTP client-mode, and
MME_Tests_SGsAP were not yet in a fully working state.
In server-mode, we have a conn_id for the listening socket and a conn_id
for the accepted socket; track them properly.
Moreover, in server node we definetly need some sort of event to wait
for the client to connect; introduce it.
Based on existing work in Iuh_Emulation.
Change-Id: Iccf4ac96c56e947529f0ffc06428e2325a115d50
---
M library/SGsAP_Emulation.ttcn
M mme/MME_Tests.ttcn
M msc/MSC_Tests.ttcn
3 files changed, 111 insertions(+), 11 deletions(-)
Approvals:
  fixeria: Looks good to me, approved
  laforge: Looks good to me, but someone else must approve
  Jenkins Builder: Verified
  osmith: Looks good to me, but someone else must approve

diff --git a/library/SGsAP_Emulation.ttcn b/library/SGsAP_Emulation.ttcn
index bb125a5..da5a311 100644
--- a/library/SGsAP_Emulation.ttcn
+++ b/library/SGsAP_Emulation.ttcn
@@ -34,6 +34,7 @@
 import from SCTP_Templates all;
 import from Osmocom_Types all;
 import from IPL4asp_Types all;
+import from Misc_Helpers all;
 import from DNS_Helpers all;
 import from MobileL3_Types all;
@@ -48,9 +49,20 @@
    inout PDU_SGsAP, PDU_ML3_MS_NW, PDU_ML3_NW_MS;
 } with { extension "internal" };
+type enumerated SGsAPEM_EventUpDown {
+	SGsAPEM_EVENT_DOWN,
+	SGsAPEM_EVENT_UP
+}
+
+/* an event indicating us whether or not a connection is physically up or down,
+ * and whether we have received an ID_ACK */
+type union SGsAPEM_Event {
+	SGsAPEM_EventUpDown	up_down
+}
+
 /* global test port e.g. for non-imsi/conn specific messages */
 type port SGsAP_PT message {
-	inout PDU_SGsAP;
+	inout PDU_SGsAP, SGsAPEM_Event;
 } with { extension "internal" };
@@ -76,8 +88,10 @@
    /* test port for unit data messages */
    port SGsAP_PT SGsAP_UNIT;
+	var SGsAP_conn_parameters g_pars;
    var charstring g_sgsap_id;
-	var integer g_sgsap_conn_id := -1;
+	var integer g_self_conn_id := -1;
+	var IPL4asp_Types.ConnectionId g_last_conn_id := -1; /* server only */
 }
type function SGsAPCreateCallback(PDU_SGsAP msg, hexstring imsi, charstring id)
@@ -101,7 +115,7 @@
 function tr_SGsAP_RecvFrom_R(template PDU_SGsAP msg)
 runs on SGsAP_Emulation_CT return template SGsAP_RecvFrom {
    var template SGsAP_RecvFrom mrf := {
-		connId := g_sgsap_conn_id,
+		connId := ?,
    	remName := ?,
    	remPort := ?,
    	locName := ?,
@@ -246,13 +260,35 @@
    return omit;
 }
+private function emu_is_server() runs on SGsAP_Emulation_CT return boolean {
+	return g_pars.remote_sctp_port == -1;
+}
+
+/* Resolve TCP/IP connection identifier depending on server/client mode */
+private function f_sgsap_conn_id()
+runs on SGsAP_Emulation_CT return IPL4asp_Types.ConnectionId {
+	var IPL4asp_Types.ConnectionId conn_id;
+
+	if (not emu_is_server()) {
+		conn_id := g_self_conn_id;
+	} else {
+		conn_id := g_last_conn_id;
+	}
+
+	if (conn_id == -1) { /* Just to be sure */
+		Misc_Helpers.f_shutdown(__FILE__, __LINE__, fail, "Connection is not established");
+	}
+
+	return conn_id;
+}
+
 private function f_sgsap_xceive(template (value) PDU_SGsAP tx,
    			template PDU_SGsAP rx_t := ?)
 runs on SGsAP_Emulation_CT  return PDU_SGsAP {
    timer T := 10.0;
    var SGsAP_RecvFrom mrf;
-	SGsAP.send(t_SGsAP_Send(g_sgsap_conn_id, tx));
+	SGsAP.send(t_SGsAP_Send(f_sgsap_conn_id(), tx));
    alt {
    [] SGsAP.receive(tr_SGsAP_RecvFrom_R(rx_t)) -> value mrf { }
    [] SGsAP.receive(tr_SctpAssocChange) { repeat; }
@@ -265,8 +301,15 @@
    return mrf.msg;
 }
+private function f_send_SGsAPEM_Event(template (value) SGsAPEM_Event evt) runs on SGsAP_Emulation_CT {
+	if (SGsAP_UNIT.checkstate("Connected")) {
+		SGsAP_UNIT.send(evt);
+	}
+}
+
 function main(SGsAPOps ops, SGsAP_conn_parameters p, charstring id) runs on SGsAP_Emulation_CT {
    var Result res;
+	g_pars := p;
    g_sgsap_id := id;
    f_imsi_table_init();
    f_expect_table_init();
@@ -281,10 +324,14 @@
    						        { sctp := valueof(ts_SctpTuple) });
    }
    if (not ispresent(res.connId)) {
-		setverdict(fail, "Could not connect SGsAP socket, check your configuration");
-		mtc.stop;
+		Misc_Helpers.f_shutdown(__FILE__, __LINE__, fail, "Could not connect SGsAP socket, check your configuration");
    }
-	g_sgsap_conn_id := res.connId;
+	g_self_conn_id := res.connId;
+
+	/* notify user about SCTP establishment */
+	if (p.remote_sctp_port != -1) {
+		f_send_SGsAPEM_Event(SGsAPEM_Event:{up_down:=SGsAPEM_EVENT_UP});
+	}
while (true) {
    	var SGsAP_ConnHdlr vc_conn;
@@ -295,30 +342,41 @@
    	var SGsAP_RecvFrom mrf;
    	var PDU_SGsAP msg;
    	var charstring vlr_name, mme_name;
+		var ASP_Event asp_evt;
alt {
+		/* SGsAP UNITDATA from client */
+		[] SGsAP_UNIT.receive(PDU_SGsAP:?) -> value msg sender vc_conn {
+			/* Pass message through */
+			SGsAP.send(t_SGsAP_Send(f_sgsap_conn_id(), msg));
+			}
+
    	/* SGsAP from client */
    	[] SGsAP_CLIENT.receive(PDU_SGsAP:?) -> value msg sender vc_conn {
    		/* Pass message through */
    		/* TODO: check which ConnectionID client has allocated + store in table? */
-			SGsAP.send(t_SGsAP_Send(g_sgsap_conn_id, msg));
+			SGsAP.send(t_SGsAP_Send(f_sgsap_conn_id(), msg));
    		}
    	/* DTAP/MobileL3 from client (emulated MS): wrap in SGsAP-UL-UD and send */
    	[] SGsAP_CLIENT.receive(PDU_ML3_MS_NW:?) -> value l3_mo sender vc_conn {
    		var octetstring l3_enc := enc_PDU_ML3_MS_NW(l3_mo);
    		imsi := f_imsi_by_comp(vc_conn);
    		msg := valueof(ts_SGsAP_UL_UD(imsi, l3_enc));
-			SGsAP.send(t_SGsAP_Send(g_sgsap_conn_id, msg));
+			SGsAP.send(t_SGsAP_Send(f_sgsap_conn_id(), msg));
    		}
    	[] SGsAP_CLIENT.receive(PDU_ML3_NW_MS:?) -> value l3_mt sender vc_conn {
    		var octetstring l3_enc := enc_PDU_ML3_NW_MS(l3_mt);
    		imsi := f_imsi_by_comp(vc_conn);
    		msg := valueof(ts_SGsAP_DL_UD(imsi, l3_enc));
-			SGsAP.send(t_SGsAP_Send(g_sgsap_conn_id, msg));
+			SGsAP.send(t_SGsAP_Send(f_sgsap_conn_id(), msg));
    		}
/* DTAP/MobileL3 from MSC/VLR to MS wrapped in SGsAP-DL-UD: Extract, decode, forward */
    	[] SGsAP.receive(tr_SGsAP_RecvFrom_R(tr_SGsAP_DL_UD(?,?))) -> value mrf {
+			if (not match(mrf.connId, f_sgsap_conn_id())) {
+				Misc_Helpers.f_shutdown(__FILE__, __LINE__, fail,
+							log2str("Received message from unexpected conn_id!", mrf));
+			}
    		var octetstring l3_enc := mrf.msg.sGsAP_DOWNLINK_UNITDATA.nAS_MessageContainer.nAS_MessageContainer;
    		imsi := mrf.msg.sGsAP_DOWNLINK_UNITDATA.iMSI.iMSI.digits;
    		vc_conn := f_comp_by_imsi(imsi);
@@ -326,6 +384,10 @@
    		SGsAP_CLIENT.send(l3_mt) to vc_conn;
    		}
    	[] SGsAP.receive(tr_SGsAP_RecvFrom_R(tr_SGsAP_UL_UD(?,?))) -> value mrf {
+			if (not match(mrf.connId, f_sgsap_conn_id())) {
+				Misc_Helpers.f_shutdown(__FILE__, __LINE__, fail,
+							log2str("Received message from unexpected conn_id!", mrf));
+			}
    		var octetstring l3_enc := mrf.msg.sGsAP_UPLINK_UNITDATA.nAS_MessageContainer.nAS_MessageContainer;
    		imsi := mrf.msg.sGsAP_UPLINK_UNITDATA.iMSI.iMSI.digits;
    		l3_mo := dec_PDU_ML3_MS_NW(l3_enc);
@@ -336,6 +398,10 @@
/* any other SGsAP from MSC/VLR */
    	[] SGsAP.receive(tr_SGsAP_RecvFrom_R(?)) -> value mrf {
+			if (not match(mrf.connId, f_sgsap_conn_id())) {
+				Misc_Helpers.f_shutdown(__FILE__, __LINE__, fail,
+							log2str("Received message from unexpected conn_id!", mrf));
+			}
    		imsi_t := f_SGsAP_get_imsi(mrf.msg);
    		if (isvalue(imsi_t)) {
    			imsi := valueof(imsi_t.iMSI.digits);
@@ -351,12 +417,39 @@
    			/* message contained no IMSI; is not IMSI-oriented */
    			var template PDU_SGsAP resp := ops.unitdata_cb.apply(mrf.msg);
    			if (isvalue(resp)) {
-					SGsAP.send(t_SGsAP_Send(g_sgsap_conn_id, valueof(resp)));
+					SGsAP.send(t_SGsAP_Send(f_sgsap_conn_id(), valueof(resp)));
    			}
    		}
    		}
    	[] SGsAP.receive(tr_SctpAssocChange) { }
    	[] SGsAP.receive(tr_SctpPeerAddrChange)  { }
+		[] SGsAP.receive(tr_SctpShutDownEvent) {
+			log("SGsAP: SCTP shutdown");
+			g_self_conn_id := -1;
+			f_send_SGsAPEM_Event(SGsAPEM_Event:{up_down:=SGsAPEM_EVENT_DOWN}); /* TODO: send asp_evt.sctpShutDownEvent.clientId */
+			if (not emu_is_server()) {
+				self.stop;
+			}
+		}
+		/* server only */
+		[] SGsAP.receive(ASP_Event:{connOpened:=?}) -> value asp_evt {
+			if (not emu_is_server()) {
+				Misc_Helpers.f_shutdown(__FILE__, __LINE__, fail,
+							log2str("Unexpected event receiver in client mode", asp_evt));
+			}
+			g_last_conn_id := asp_evt.connOpened.connId;
+			log("Established a new SGsAP connection (conn_id=", g_last_conn_id, ")");
+
+			f_send_SGsAPEM_Event(SGsAPEM_Event:{up_down:=SGsAPEM_EVENT_UP}); /* TODO: send g_last_conn_id */
+		}
+		[] SGsAP.receive(ASP_Event:{connClosed:=?}) -> value asp_evt {
+			log("SGsAP: Closed");
+			g_self_conn_id := -1;
+			f_send_SGsAPEM_Event(SGsAPEM_Event:{up_down:=SGsAPEM_EVENT_DOWN}); /* TODO: send asp_evt.connClosed.connId */
+			if (not emu_is_server()) {
+				self.stop;
+			}
+		}
    	[] SGsAP_PROC.getcall(SGsAPEM_register:{?,?}) -> param(imsi, vc_conn) {
    		f_create_expect(imsi, vc_conn);
    		SGsAP_PROC.reply(SGsAPEM_register:{imsi, vc_conn}) to vc_conn;
diff --git a/mme/MME_Tests.ttcn b/mme/MME_Tests.ttcn
index 2847bcc..885b727 100644
--- a/mme/MME_Tests.ttcn
+++ b/mme/MME_Tests.ttcn
@@ -154,6 +154,8 @@
    connect(vc_SGsAP:SGsAP_PROC, self:SGsAP_PROC);
    connect(vc_SGsAP:SGsAP_UNIT, self:SGsAP_UNIT);
    vc_SGsAP.start(SGsAP_Emulation.main(ops, pars, id));
+
+	SGsAP_UNIT.receive(SGsAPEM_Event:{up_down:=SGsAPEM_EVENT_UP});
 }
/* send incoming unit data messages (like reset) to global S1AP_UNIT port */
diff --git a/msc/MSC_Tests.ttcn b/msc/MSC_Tests.ttcn
index 47b2c5e..ceddc11 100644
--- a/msc/MSC_Tests.ttcn
+++ b/msc/MSC_Tests.ttcn
@@ -106,7 +106,9 @@
    var GSUP_Emulation_CT vc_GSUP;
    var IPA_Emulation_CT vc_GSUP_IPA;
    var SMPP_Emulation_CT vc_SMPP;
+
    var SGsAP_Emulation_CT vc_SGsAP;
+	port SGsAP_PT SGsAP_UNIT;
/* only to get events from IPA underneath GSUP */
    port IPA_CTRL_PT GSUP_IPA_EVENT;
@@ -284,7 +286,10 @@
vc_SGsAP := SGsAP_Emulation_CT.create(id);
    map(vc_SGsAP:SGsAP, system:SGsAP_CODEC_PT);
+	connect(vc_SGsAP:SGsAP_UNIT, self:SGsAP_UNIT);
    vc_SGsAP.start(SGsAP_Emulation.main(ops, pars, id));
+
+	SGsAP_UNIT.receive(SGsAPEM_Event:{up_down:=SGsAPEM_EVENT_UP});
 }
-- 
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Gerrit-MessageType: merged
Gerrit-Project: osmo-ttcn3-hacks
Gerrit-Branch: master
Gerrit-Change-Id: Iccf4ac96c56e947529f0ffc06428e2325a115d50
Gerrit-Change-Number: 41083
Gerrit-PatchSet: 5
Gerrit-Owner: pespin pespin@sysmocom.de
Gerrit-Reviewer: Jenkins Builder
Gerrit-Reviewer: fixeria vyanitskiy@sysmocom.de
Gerrit-Reviewer: laforge laforge@osmocom.org
Gerrit-Reviewer: osmith osmith@sysmocom.de
Gerrit-Reviewer: pespin pespin@sysmocom.de



    

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[M] Change in osmo-ttcn3-hacks[master]: SGsAP_Emulation: Introduce proper support for server-mode