Refactor RDP proxy handling and update related tests

agents/rap-node-agent/internal/vpnruntime/fabric_transport_test.go

@@ -426,6 +426,59 @@ func TestFabricSessionPacketTransportRunFrameIngressDeliversInbox(t *testing.T)
 	}
 }
 
+func TestFabricSessionPacketPeerTransportSendsReplyToLatestRegisteredPeer(t *testing.T) {
+	inbox := NewFabricPacketInbox(4)
+	registry := NewFabricSessionPacketPeerRegistry()
+	sender := &recordingFrameSender{}
+	frame, err := NewFabricVPNPacketDataFrame(FabricVPNPacketFrameInput{
+		StreamID:        7,
+		VPNConnectionID: "vpn-1",
+		Direction:       FabricDirectionClientToGateway,
+		Packets:         [][]byte{[]byte("request")},
+	})
+	if err != nil {
+		t.Fatalf("frame: %v", err)
+	}
+	handled, err := registry.RegisterFrame(context.Background(), sender, frame)
+	if err != nil || !handled {
+		t.Fatalf("register frame handled=%v err=%v", handled, err)
+	}
+	if err := inbox.DeliverFabricSessionFrame(context.Background(), frame); err != nil {
+		t.Fatalf("deliver frame: %v", err)
+	}
+	transport := &FabricSessionPacketPeerTransport{
+		Registry:        registry,
+		Inbox:           inbox,
+		VPNConnectionID: "vpn-1",
+	}
+	requests, err := transport.ReceiveGatewayPacketBatch(context.Background(), time.Second)
+	if err != nil || len(requests) != 1 || string(requests[0]) != "request" {
+		t.Fatalf("requests=%q err=%v", requests, err)
+	}
+	if err := transport.SendGatewayPacketBatch(context.Background(), [][]byte{[]byte("reply")}); err != nil {
+		t.Fatalf("send reply: %v", err)
+	}
+	if len(sender.frames) != 1 {
+		t.Fatalf("sent frames = %d, want 1", len(sender.frames))
+	}
+	payload, err := DecodeFabricVPNPacketDataFrame(sender.frames[0])
+	if err != nil {
+		t.Fatalf("decode reply: %v", err)
+	}
+	if payload.Direction != FabricDirectionGatewayToClient || string(payload.Packets[0]) != "reply" {
+		t.Fatalf("reply payload = %+v", payload)
+	}
+}
+
+type recordingFrameSender struct {
+	frames []fabricproto.Frame
+}
+
+func (s *recordingFrameSender) SendFrame(_ context.Context, frame fabricproto.Frame) error {
+	s.frames = append(s.frames, frame)
+	return nil
+}
+
 func TestFabricSessionPacketTransportReceiveReadsPumpFrames(t *testing.T) {
 	inbox := NewFabricPacketInbox(4)
 	receiver := memoryFabricSessionReceiver{