allow gossipsub to graylist peers based on score

floodsub.go

@@ -67,6 +67,10 @@ func (fs *FloodSubRouter) EnoughPeers(topic string, suggested int) bool {
 	return false
 }
 
+func (fs *FloodSubRouter) AcceptFrom(peer.ID) bool {
+	return true
+}
+
 func (fs *FloodSubRouter) HandleRPC(rpc *RPC) {}
 
 func (fs *FloodSubRouter) Publish(msg *Message) {

gossipsub.go

@@ -74,10 +74,18 @@ func NewGossipSub(ctx context.Context, h host.Host, opts ...Option) (*PubSub, er
 }
 
 // WithPeerScore is a gossipsub router option that enables peer scoring.
+//
 // gossipThreshold is the score threshold below which gossip propagation is supressed.
+//
 // publishThreshold is the score threshold below which we shouldn't publish when using flood
-// publishing (also applies to fanout and floodsub peers).
-func WithPeerScore(params *PeerScoreParams, gossipThreshold float64, publishThreshold float64) Option {
+//  publishing (also applies to fanout and floodsub peers).
+//
+// graylistThreshold is the score threshold below which message processing is supressed altogether,
+//  implementing an effective graylist according to peer score.
+//
+// These thresholds should generally be negative, allowing some information to disseminate from low
+//  scoring peers.
+func WithPeerScore(params *PeerScoreParams, gossipThreshold, publishThreshold, graylistThreshold float64) Option {
 	return func(ps *PubSub) error {
 		gs, ok := ps.rt.(*GossipSubRouter)
 		if !ok {
@@ -87,6 +95,7 @@ func WithPeerScore(params *PeerScoreParams, gossipThreshold float64, publishThre
 		gs.score = newPeerScore(gs, params)
 		gs.gossipThreshold = gossipThreshold
 		gs.publishThreshold = publishThreshold
+		gs.graylistThreshold = graylistThreshold
 
 		// hook the tracer
 		if ps.tracer != nil {
@@ -145,6 +154,9 @@ type GossipSubRouter struct {
 	// when using flood publishing or the peer is a fanout or floodsub peer.
 	publishThreshold float64
 
+	// threshold for peer score before we graylist the peer and silently ignore its RPCs
+	graylistThreshold float64
+
 	// whether to use flood publishing
 	floodPublish bool
 }
@@ -218,6 +230,10 @@ func (gs *GossipSubRouter) EnoughPeers(topic string, suggested int) bool {
 	return false
 }
 
+func (gs *GossipSubRouter) AcceptFrom(p peer.ID) bool {
+	return gs.score.Score(p) >= gs.graylistThreshold
+}
+
 func (gs *GossipSubRouter) HandleRPC(rpc *RPC) {
 	ctl := rpc.GetControl()
 	if ctl == nil {

pubsub.go

@@ -151,6 +151,11 @@ type PubSubRouter interface {
 	// EnoughPeers returns whether the router needs more peers before it's ready to publish new records.
 	// Suggested (if greater than 0) is a suggested number of peers that the router should need.
 	EnoughPeers(topic string, suggested int) bool
+	// AcceptFrom is invoked on any incoming message before pushing it to the validation pipeline
+	// or processing control information.
+	// Allows routers with internal scoring to vet peers before commiting any processing resources
+	// to the message and implement an affective graylist.
+	AcceptFrom(peer.ID) bool
 	// HandleRPC is invoked to process control messages in the RPC envelope.
 	// It is invoked after subscriptions and payload messages have been processed.
 	HandleRPC(*RPC)
@@ -779,6 +784,12 @@ func (p *PubSub) handleIncomingRPC(rpc *RPC) {
 		}
 	}
 
+	// ask the router to vet the peer before commiting any processing resources
+	if !p.rt.AcceptFrom(rpc.from) {
+		log.Warningf("received message from router graylisted peer %s. Dropping RPC", rpc.from)
+		return
+	}
+
 	for _, pmsg := range rpc.GetPublish() {
 		if !p.subscribedToMsg(pmsg) {
 			log.Warning("received message we didn't subscribe to. Dropping.")

randomsub.go

@@ -86,6 +86,10 @@ func (rs *RandomSubRouter) EnoughPeers(topic string, suggested int) bool {
 	return false
 }
 
+func (rs *RandomSubRouter) AcceptFrom(peer.ID) bool {
+	return true
+}
+
 func (rs *RandomSubRouter) HandleRPC(rpc *RPC) {}
 
 func (rs *RandomSubRouter) Publish(msg *Message) {