lib: GTP_Emulation: Allow receiving packets with TEID 0

Some GTP messages like Echo Request, Echo Reply and Ind Error don't use
the TEID value. According to 3GPP TS 29.060 sec 9.3.1 in those cases the TEID is
set to 0:

"""
- TEID: Contains the Tunnel Endpoint Identifier for the tunnel to which this T-PDU belongs. The TEID shall be
used by the receiving entity to find the PDP context, except for the following cases:
- The Echo Request/Response and Supported Extension Headers notification messages, where the Tunnel
Endpoint Identifier shall be set to all zeroes.
- The Error Indication message where the Tunnel Endpoint Identifier shall be set to all zeros.
"""

Change-Id: Ic702b78028e850ed961ef805f35e10a42da34e56

1 files changed, 11 insertions, 2 deletions

diff --git a/library/GTP_Emulation.ttcn b/library/GTP_Emulation.ttcn
index 534fdef8..615309a8 100644
--- a/library/GTP_Emulation.ttcn
+++ b/library/GTP_Emulation.ttcn
@@ -185,10 +185,19 @@ function main(GtpEmulationCfg cfg) runs on GTP_Emulation_CT {
 		var template hexstring imsi_t := f_gtpc_extract_imsi(g1c_ud.gtpc);
 		if (isvalue(imsi_t)) {
 			vc_conn := f_comp_by_imsi(valueof(imsi_t));
-		} else {
+			CLIENT.send(g1c_ud) to vc_conn;
+		} else if(g1c_ud.gtpc.teid != int2oct(0, 4)) {
 			vc_conn := f_comp_by_teid(g1c_ud.gtpc.teid);
+			CLIENT.send(g1c_ud) to vc_conn;
+		} else {
+			/* Send to all clients */
+			var integer i;
+			for (i := 0; i < sizeof(TidTable); i := i+1) {
+				if (isbound(TidTable[i].teid) and TidTable[i].teid == teid) {
+					CLIENT.send(g1c_ud) to TidTable[i].vc_conn;
+				}
+			}
 		}
-		CLIENT.send(g1c_ud) to vc_conn;
 		}
 	[] GTPU.receive(Gtp1uUnitdata:?) -> value g1u_ud {
 		vc_conn := f_comp_by_teid(g1u_ud.gtpu.teid);