refactor: separate NetworkOverlay from Overlay

...since connections only need to know about the latter.

prog/weaver/main.go

@@ -150,7 +150,7 @@ func main() {
 	}
 	config.ProtocolMinVersion = byte(protocolMinVersion)
 
-	var fastDPOverlay weave.Overlay
+	var fastDPOverlay weave.NetworkOverlay
 	if datapathName != "" {
 		// A datapath name implies that "Bridge" and "Overlay"
 		// packet handling use fast datapath, although other

router/fastdp.go

@@ -297,7 +297,7 @@ type fastDatapathOverlay struct {
 	*FastDatapath
 }
 
-func (fastdp *FastDatapath) Overlay() Overlay {
+func (fastdp *FastDatapath) Overlay() NetworkOverlay {
 	return fastDatapathOverlay{fastdp}
 }
 

router/overlay.go

@@ -4,15 +4,22 @@ import (
 	"net"
 )
 
-// Interface to overlay network packet handling
 type Overlay interface {
-	// Start consuming forwarded packets.
-	StartConsumingPackets(*Peer, *Peers, OverlayConsumer) error
+	// Enhance a features map with overlay-related features
+	AddFeaturesTo(map[string]string)
 
 	// Prepare on overlay connection. The connection should remain
 	// passive until it has been Confirm()ed.
 	PrepareConnection(OverlayConnectionParams) (OverlayConnection, error)
 
+	// Obtain diagnostic information specific to the overlay
+	Diagnostics() interface{}
+}
+
+// Interface to overlay network packet handling
+type NetworkOverlay interface {
+	Overlay
+
 	// The routes have changed, so any cached information should
 	// be discarded.
 	InvalidateRoutes()
@@ -20,11 +27,8 @@ type Overlay interface {
 	// A mapping of a short id to a peer has changed
 	InvalidateShortIDs()
 
-	// Enhance a features map with overlay-related features
-	AddFeaturesTo(map[string]string)
-
-	// Obtain diagnostic information specific to the overlay
-	Diagnostics() interface{}
+	// Start consuming forwarded packets.
+	StartConsumingPackets(*Peer, *Peers, OverlayConsumer) error
 }
 
 type OverlayConnectionParams struct {

router/overlay_switch.go

@@ -13,16 +13,16 @@ import (
 // uses the best one that seems to be working.
 
 type OverlaySwitch struct {
-	overlays      map[string]Overlay
+	overlays      map[string]NetworkOverlay
 	overlayNames  []string
-	compatOverlay Overlay
+	compatOverlay NetworkOverlay
 }
 
 func NewOverlaySwitch() *OverlaySwitch {
-	return &OverlaySwitch{overlays: make(map[string]Overlay)}
+	return &OverlaySwitch{overlays: make(map[string]NetworkOverlay)}
 }
 
-func (osw *OverlaySwitch) Add(name string, overlay Overlay) {
+func (osw *OverlaySwitch) Add(name string, overlay NetworkOverlay) {
 	// check for repeated names
 	if _, present := osw.overlays[name]; present {
 		log.Fatal("OverlaySwitch: repeated overlay name")
@@ -32,7 +32,7 @@ func (osw *OverlaySwitch) Add(name string, overlay Overlay) {
 	osw.overlayNames = append(osw.overlayNames, name)
 }
 
-func (osw *OverlaySwitch) SetCompatOverlay(overlay Overlay) {
+func (osw *OverlaySwitch) SetCompatOverlay(overlay NetworkOverlay) {
 	osw.compatOverlay = overlay
 }
 
@@ -70,7 +70,7 @@ func (osw *OverlaySwitch) StartConsumingPackets(localPeer *Peer, peers *Peers, c
 }
 
 type namedOverlay struct {
-	Overlay
+	NetworkOverlay
 	name string
 }
 
@@ -82,7 +82,7 @@ func (osw *OverlaySwitch) commonOverlays(params OverlayConnectionParams) ([]name
 		peerOverlays = strings.Split(overlaysFeature, " ")
 	}
 
-	common := make(map[string]Overlay)
+	common := make(map[string]NetworkOverlay)
 	for _, name := range peerOverlays {
 		if overlay := osw.overlays[name]; overlay != nil {
 			common[name] = overlay

router/router.go

@@ -70,7 +70,7 @@ type Router struct {
 	acceptLimiter   *TokenBucket
 }
 
-func NewRouter(config Config, name PeerName, nickName string, overlay Overlay) *Router {
+func NewRouter(config Config, name PeerName, nickName string, overlay NetworkOverlay) *Router {
 	router := &Router{Config: config, gossipChannels: make(GossipChannels)}
 
 	if router.Bridge == nil {
@@ -108,7 +108,7 @@ func NewRouter(config Config, name PeerName, nickName string, overlay Overlay) *
 func (router *Router) Start() {
 	log.Println("Sniffing traffic on", router.Bridge)
 	checkFatal(router.Bridge.StartConsumingPackets(router.handleCapturedPacket))
-	checkFatal(router.Overlay.StartConsumingPackets(router.Ourself.Peer, router.Peers, router.handleForwardedPacket))
+	checkFatal(router.Overlay.(NetworkOverlay).StartConsumingPackets(router.Ourself.Peer, router.Peers, router.handleForwardedPacket))
 	router.listenTCP(router.Port)
 }
 
@@ -218,7 +218,7 @@ func (router *Router) handleForwardedPacket(key ForwardPacketKey) FlowOp {
 
 		// We need to clear out any flows destined to the MAC
 		// that forward to the old peer.
-		router.Overlay.InvalidateRoutes()
+		router.Overlay.(NetworkOverlay).InvalidateRoutes()
 	}
 
 	router.PacketLogging.LogForwardPacket("Injecting", key)

router/sleeve.go

@@ -71,7 +71,7 @@ type SleeveOverlay struct {
 	forwarders map[PeerName]*sleeveForwarder
 }
 
-func NewSleeveOverlay(localPort int) Overlay {
+func NewSleeveOverlay(localPort int) NetworkOverlay {
 	return &SleeveOverlay{localPort: localPort}
 }