Allow waiting for Endpoint worker goroutines to finish.

Updates #837

PiperOrigin-RevId: 277325162

pkg/tcpip/stack/registration.go

@@ -67,6 +67,20 @@ type TransportEndpoint interface {
 	// HandleControlPacket is called by the stack when new control (e.g.,
 	// ICMP) packets arrive to this transport endpoint.
 	HandleControlPacket(id TransportEndpointID, typ ControlType, extra uint32, vv buffer.VectorisedView)
+
+	// Close puts the endpoint in a closed state and frees all resources
+	// associated with it. This cleanup may happen asynchronously. Wait can
+	// be used to block on this asynchronous cleanup.
+	Close()
+
+	// Wait waits for any worker goroutines owned by the endpoint to stop.
+	//
+	// An endpoint can be requested to stop its worker goroutines by calling
+	// its Close method.
+	//
+	// Wait will not block if the endpoint hasn't started any goroutines
+	// yet, even if it might later.
+	Wait()
 }
 
 // RawTransportEndpoint is the interface that needs to be implemented by raw

pkg/tcpip/stack/transport_demuxer.go

@@ -240,6 +240,26 @@ func (ep *multiPortEndpoint) handlePacketAll(r *Route, id TransportEndpointID, v
 	ep.mu.RUnlock() // Don't use defer for performance reasons.
 }
 
+// Close implements stack.TransportEndpoint.Close.
+func (ep *multiPortEndpoint) Close() {
+	ep.mu.RLock()
+	eps := append([]TransportEndpoint(nil), ep.endpointsArr...)
+	ep.mu.RUnlock()
+	for _, e := range eps {
+		e.Close()
+	}
+}
+
+// Wait implements stack.TransportEndpoint.Wait.
+func (ep *multiPortEndpoint) Wait() {
+	ep.mu.RLock()
+	eps := append([]TransportEndpoint(nil), ep.endpointsArr...)
+	ep.mu.RUnlock()
+	for _, e := range eps {
+		e.Wait()
+	}
+}
+
 // singleRegisterEndpoint tries to add an endpoint to the multiPortEndpoint
 // list. The list might be empty already.
 func (ep *multiPortEndpoint) singleRegisterEndpoint(t TransportEndpoint, reusePort bool) *tcpip.Error {

pkg/tcpip/stack/transport_test.go

@@ -225,8 +225,9 @@ func (f *fakeTransportEndpoint) IPTables() (iptables.IPTables, error) {
 	return iptables.IPTables{}, nil
 }
 
-func (f *fakeTransportEndpoint) Resume(*stack.Stack) {
-}
+func (f *fakeTransportEndpoint) Resume(*stack.Stack) {}
+
+func (f *fakeTransportEndpoint) Wait() {}
 
 type fakeTransportGoodOption bool
 

pkg/tcpip/transport/icmp/endpoint.go

@@ -798,3 +798,6 @@ func (e *endpoint) Info() tcpip.EndpointInfo {
 func (e *endpoint) Stats() tcpip.EndpointStats {
 	return &e.stats
 }
+
+// Wait implements stack.TransportEndpoint.Wait.
+func (*endpoint) Wait() {}

pkg/tcpip/transport/raw/endpoint.go

@@ -641,3 +641,6 @@ func (e *endpoint) Info() tcpip.EndpointInfo {
 func (e *endpoint) Stats() tcpip.EndpointStats {
 	return &e.stats
 }
+
+// Wait implements stack.TransportEndpoint.Wait.
+func (*endpoint) Wait() {}

pkg/tcpip/transport/tcp/endpoint.go

@@ -2399,6 +2399,22 @@ func (e *endpoint) Stats() tcpip.EndpointStats {
 	return &e.stats
 }
 
+// Wait implements stack.TransportEndpoint.Wait.
+func (e *endpoint) Wait() {
+	waitEntry, notifyCh := waiter.NewChannelEntry(nil)
+	e.waiterQueue.EventRegister(&waitEntry, waiter.EventHUp)
+	defer e.waiterQueue.EventUnregister(&waitEntry)
+	for {
+		e.mu.Lock()
+		running := e.workerRunning
+		e.mu.Unlock()
+		if !running {
+			break
+		}
+		<-notifyCh
+	}
+}
+
 func mssForRoute(r *stack.Route) uint16 {
 	// TODO(b/143359391): Respect TCP Min and Max size.
 	return uint16(r.MTU() - header.TCPMinimumSize)

pkg/tcpip/transport/udp/endpoint.go

@@ -1234,6 +1234,9 @@ func (e *endpoint) Stats() tcpip.EndpointStats {
 	return &e.stats
 }
 
+// Wait implements tcpip.Endpoint.Wait.
+func (*endpoint) Wait() {}
+
 func isBroadcastOrMulticast(a tcpip.Address) bool {
 	return a == header.IPv4Broadcast || header.IsV4MulticastAddress(a) || header.IsV6MulticastAddress(a)
 }