feat(peer-exchange): rate limit (#1043)

Co-authored-by: Prem Chaitanya Prathi <chaitanyaprem@gmail.com>

waku/v2/protocol/peer_exchange/client.go

@@ -19,8 +19,8 @@ import (
 	"go.uber.org/zap"
 )
 
-func (wakuPX *WakuPeerExchange) Request(ctx context.Context, numPeers int, opts ...PeerExchangeOption) error {
+func (wakuPX *WakuPeerExchange) Request(ctx context.Context, numPeers int, opts ...RequestOption) error {
-	params := new(PeerExchangeParameters)
+	params := new(PeerExchangeRequestParameters)
 	params.host = wakuPX.h
 	params.log = wakuPX.log
 	params.pm = wakuPX.pm
@@ -103,7 +103,7 @@ func (wakuPX *WakuPeerExchange) Request(ctx context.Context, numPeers int, opts
 	return wakuPX.handleResponse(ctx, responseRPC.Response, params)
 }
 
-func (wakuPX *WakuPeerExchange) handleResponse(ctx context.Context, response *pb.PeerExchangeResponse, params *PeerExchangeParameters) error {
+func (wakuPX *WakuPeerExchange) handleResponse(ctx context.Context, response *pb.PeerExchangeResponse, params *PeerExchangeRequestParameters) error {
 	var discoveredPeers []struct {
 		addrInfo peer.AddrInfo
 		enr      *enode.Node

waku/v2/protocol/peer_exchange/metrics.go

@@ -39,6 +39,7 @@ var (
 	decodeRPCFailure metricsErrCategory = "decode_rpc_failure"
 	pxFailure        metricsErrCategory = "px_failure"
 	dialFailure      metricsErrCategory = "dial_failure"
+	rateLimitFailure metricsErrCategory = "ratelimit_failure"
 )
 
 // RecordError increases the counter for different error types

waku/v2/protocol/peer_exchange/protocol.go

@@ -20,6 +20,7 @@ import (
 	"github.com/waku-org/go-waku/waku/v2/protocol/peer_exchange/pb"
 	"github.com/waku-org/go-waku/waku/v2/service"
 	"go.uber.org/zap"
+	"golang.org/x/time/rate"
 )
 
 // PeerExchangeID_v20alpha1 is the current Waku Peer Exchange protocol identifier
@@ -47,12 +48,13 @@ type WakuPeerExchange struct {
 
 	peerConnector PeerConnector
 	enrCache      *enrCache
+	limiter       *rate.Limiter
 }
 
 // NewWakuPeerExchange returns a new instance of WakuPeerExchange struct
 // Takes an optional peermanager if WakuPeerExchange is being created along with WakuNode.
 // If using libp2p host, then pass peermanager as nil
-func NewWakuPeerExchange(disc *discv5.DiscoveryV5, peerConnector PeerConnector, pm *peermanager.PeerManager, reg prometheus.Registerer, log *zap.Logger) (*WakuPeerExchange, error) {
+func NewWakuPeerExchange(disc *discv5.DiscoveryV5, peerConnector PeerConnector, pm *peermanager.PeerManager, reg prometheus.Registerer, log *zap.Logger, opts ...Option) (*WakuPeerExchange, error) {
 	wakuPX := new(WakuPeerExchange)
 	wakuPX.disc = disc
 	wakuPX.metrics = newMetrics(reg)
@@ -62,6 +64,12 @@ func NewWakuPeerExchange(disc *discv5.DiscoveryV5, peerConnector PeerConnector,
 	wakuPX.pm = pm
 	wakuPX.CommonService = service.NewCommonService()
 
+	params := &PeerExchangeParameters{}
+	for _, opt := range opts {
+		opt(params)
+	}
+
+	wakuPX.limiter = params.limiter
 	return wakuPX, nil
 }
 
@@ -87,6 +95,14 @@ func (wakuPX *WakuPeerExchange) start() error {
 func (wakuPX *WakuPeerExchange) onRequest() func(network.Stream) {
 	return func(stream network.Stream) {
 		logger := wakuPX.log.With(logging.HostID("peer", stream.Conn().RemotePeer()))
+
+		if wakuPX.limiter != nil && !wakuPX.limiter.Allow() {
+			wakuPX.metrics.RecordError(rateLimitFailure)
+			wakuPX.log.Error("exceeds the rate limit")
+			// TODO: peer exchange protocol should contain an err field
+			return
+		}
+
 		requestRPC := &pb.PeerExchangeRPC{}
 		reader := pbio.NewDelimitedReader(stream, math.MaxInt32)
 		err := reader.ReadMsg(requestRPC)

waku/v2/protocol/peer_exchange/waku_peer_exchange_option.go

@@ -8,9 +8,23 @@ import (
 	"github.com/multiformats/go-multiaddr"
 	"github.com/waku-org/go-waku/waku/v2/peermanager"
 	"go.uber.org/zap"
+	"golang.org/x/time/rate"
 )
 
 type PeerExchangeParameters struct {
+	limiter *rate.Limiter
+}
+
+type Option func(*PeerExchangeParameters)
+
+// WithRateLimiter is an option used to specify a rate limiter for requests received in lightpush protocol
+func WithRateLimiter(r rate.Limit, b int) Option {
+	return func(params *PeerExchangeParameters) {
+		params.limiter = rate.NewLimiter(r, b)
+	}
+}
+
+type PeerExchangeRequestParameters struct {
 	host              host.Host
 	selectedPeer      peer.ID
 	peerAddr          multiaddr.Multiaddr
@@ -22,11 +36,11 @@ type PeerExchangeParameters struct {
 	clusterID         int
 }
 
-type PeerExchangeOption func(*PeerExchangeParameters) error
+type RequestOption func(*PeerExchangeRequestParameters) error
 
 // WithPeer is an option used to specify the peerID to fetch peers from
-func WithPeer(p peer.ID) PeerExchangeOption {
+func WithPeer(p peer.ID) RequestOption {
-	return func(params *PeerExchangeParameters) error {
+	return func(params *PeerExchangeRequestParameters) error {
 		params.selectedPeer = p
 		if params.peerAddr != nil {
 			return errors.New("peerAddr and peerId options are mutually exclusive")
@@ -38,8 +52,8 @@ func WithPeer(p peer.ID) PeerExchangeOption {
 // WithPeerAddr is an option used to specify a peerAddress to fetch peers from
 // This new peer will be added to peerStore.
 // Note that this option is mutually exclusive to WithPeerAddr, only one of them can be used.
-func WithPeerAddr(pAddr multiaddr.Multiaddr) PeerExchangeOption {
+func WithPeerAddr(pAddr multiaddr.Multiaddr) RequestOption {
-	return func(params *PeerExchangeParameters) error {
+	return func(params *PeerExchangeRequestParameters) error {
 		params.peerAddr = pAddr
 		if params.selectedPeer != "" {
 			return errors.New("peerAddr and peerId options are mutually exclusive")
@@ -53,8 +67,8 @@ func WithPeerAddr(pAddr multiaddr.Multiaddr) PeerExchangeOption {
 // from that list assuming it supports the chosen protocol, otherwise it will chose a peer
 // from the node peerstore
 // Note: this option can only be used if WakuNode is initialized which internally intializes the peerManager
-func WithAutomaticPeerSelection(fromThesePeers ...peer.ID) PeerExchangeOption {
+func WithAutomaticPeerSelection(fromThesePeers ...peer.ID) RequestOption {
-	return func(params *PeerExchangeParameters) error {
+	return func(params *PeerExchangeRequestParameters) error {
 		params.peerSelectionType = peermanager.Automatic
 		params.preferredPeers = fromThesePeers
 		return nil
@@ -65,8 +79,8 @@ func WithAutomaticPeerSelection(fromThesePeers ...peer.ID) PeerExchangeOption {
 // with the lowest ping. If a list of specific peers is passed, the peer will be chosen
 // from that list assuming it supports the chosen protocol, otherwise it will chose a peer
 // from the node peerstore
-func WithFastestPeerSelection(fromThesePeers ...peer.ID) PeerExchangeOption {
+func WithFastestPeerSelection(fromThesePeers ...peer.ID) RequestOption {
-	return func(params *PeerExchangeParameters) error {
+	return func(params *PeerExchangeRequestParameters) error {
 		params.peerSelectionType = peermanager.LowestRTT
 		params.preferredPeers = fromThesePeers
 		return nil
@@ -74,15 +88,15 @@ func WithFastestPeerSelection(fromThesePeers ...peer.ID) PeerExchangeOption {
 }
 
 // DefaultOptions are the default options to be used when using the lightpush protocol
-func DefaultOptions(host host.Host) []PeerExchangeOption {
+func DefaultOptions(host host.Host) []RequestOption {
-	return []PeerExchangeOption{
+	return []RequestOption{
 		WithAutomaticPeerSelection(),
 	}
 }
 
 // Use this if you want to filter peers by specific shards
-func FilterByShard(clusterID int, shard int) PeerExchangeOption {
+func FilterByShard(clusterID int, shard int) RequestOption {
-	return func(params *PeerExchangeParameters) error {
+	return func(params *PeerExchangeRequestParameters) error {
 		params.shard = shard
 		params.clusterID = clusterID
 		return nil