feat: use max qfi in PDU session as tunnel key

clean.sh

@@ -0,0 +1,18 @@
+#!/bin/bash
+
+sudo ip xfrm policy flush
+sudo ip xfrm state flush
+
+# Remove all GRE interfaces
+GREs=$(ip link show type gre | awk 'NR%2==1 {print $2}' | cut -d @ -f 1)
+for GRE in ${GREs}; do
+    sudo ip link del ${GRE}
+    echo del ${GRE}
+done
+
+# Remove all XFRM interfaces
+XFRMIs=$(ip link show type xfrm | awk 'NR%2==1 {print $2}' | cut -d @ -f 1)
+for XFRMI in ${XFRMIs}; do
+    sudo ip link del ${XFRMI}
+    echo del ${XFRMI}
+done

internal/gtp/handler/handler.go

@@ -56,6 +56,10 @@ func forward(packet gtpQoSMsg.QoSTPDUPacket) {
 		return
 	}
 
+	// The QFI field of the GRE header is set to the QFI associated with the user data packet
+	// [Implement] we use the largest QFI in this PDU session as key
+	var tunnelKey uint8 = 0
+
 	// UE inner IP in IPSec
 	ueInnerIPAddr := ikeUe.IPSecInnerIPAddr
 
@@ -68,6 +72,7 @@ func forward(packet gtpQoSMsg.QoSTPDUPacket) {
 			cm = &ipv4.ControlMessage{
 				IfIndex: childSA.XfrmIface.Attrs().Index,
 			}
+			tunnelKey = pdusession.MaxQFI()
 			break
 		}
 	}
@@ -83,6 +88,11 @@ func forward(packet gtpQoSMsg.QoSTPDUPacket) {
 		logger.GTPLog.Tracef("QFI: %v, RQI: %v", qfi, rqi)
 	}
 
+	if tunnelKey != uint8(0) {
+		// [Implement] we use the largest QFI in this PDU session as tunnel key
+		qfi = tunnelKey
+	}
+
 	// Encasulate IPv4 packet with GRE header before forward to UE through IPsec
 	grePacket := gre.GREPacket{}
 

pkg/context/ue.go

@@ -431,3 +431,11 @@ func (ranUe *N3IWFRanUe) DetachAMF() {
 	}
 	delete(ranUe.AMF.N3iwfRanUeList, ranUe.RanUeNgapId)
 }
+
+func (pdusession PDUSession) MaxQFI() uint8 {
+	var maxQfi uint8 = 0
+	for _, qfi := range pdusession.QFIList {
+		maxQfi = max(maxQfi, qfi)
+	}
+	return maxQfi
+}

pkg/ike/handler/handler.go

@@ -1777,6 +1777,7 @@ func CreatePDUSessionChildSA(ikeUe *context.N3IWFIkeUe,
 
 			// Notify-Qos
 			ikePayload.BuildNotify5G_QOS_INFO(uint8(pduSessionID), pduSession.QFIList, true, false, 0)
+			logger.IKELog.Infoln("pduSession", pduSessionID, "QFIList:", pduSession.QFIList)
 
 			// Notify-UP_IP_ADDRESS
 			ikePayload.BuildNotifyUP_IP4_ADDRESS(n3iwfSelf.IPSecGatewayAddress)