feat: peer exchange

waku.go

@@ -332,6 +332,18 @@ func main() {
 			Usage:       "Discovery can automatically update its ENR with the IP address as seen by other nodes it communicates with.",
 			Destination: &options.DiscV5.AutoUpdate,
 		},
+		&cli.BoolFlag{
+			Name:        "peer-exchange",
+			Usage:       "Enable waku peer exchange protocol (responder side)",
+			Destination: &options.PeerExchange.Enable,
+		},
+		&cli.GenericFlag{
+			Name:  "peer-exchange-node",
+			Usage: "Peer multiaddr to send peer exchange requests to. (enables peer exchange protocol requester side)",
+			Value: &cliutils.MultiaddrValue{
+				Value: &options.PeerExchange.Node,
+			},
+		},
 		&cli.BoolFlag{
 			Name:        "dns-discovery",
 			Usage:       "Enable DNS discovery",

waku/node.go

@@ -40,6 +40,7 @@ import (
 	"github.com/status-im/go-waku/waku/v2/node"
 	"github.com/status-im/go-waku/waku/v2/protocol/filter"
 	"github.com/status-im/go-waku/waku/v2/protocol/lightpush"
+	"github.com/status-im/go-waku/waku/v2/protocol/peer_exchange"
 	"github.com/status-im/go-waku/waku/v2/protocol/relay"
 	"github.com/status-im/go-waku/waku/v2/protocol/store"
 	"github.com/status-im/go-waku/waku/v2/rest"
@@ -254,6 +255,10 @@ func Execute(options Options) {
 		nodeOpts = append(nodeOpts, node.WithDiscoveryV5(options.DiscV5.Port, bootnodes, options.DiscV5.AutoUpdate, pubsub.WithDiscoveryOpts(discovery.Limit(45), discovery.TTL(time.Duration(20)*time.Second))))
 	}
 
+	if options.PeerExchange.Enable {
+		nodeOpts = append(nodeOpts, node.WithPeerExchange())
+	}
+
 	checkForRLN(logger, options, &nodeOpts)
 
 	wakuNode, err := node.New(ctx, nodeOpts...)
@@ -272,6 +277,21 @@ func Execute(options Options) {
 		if err = wakuNode.DiscV5().Start(); err != nil {
 			logger.Fatal("starting discovery v5", zap.Error(err))
 		}
+
+		// retrieve and connect to peer exchange peers
+		if options.PeerExchange.Enable && options.PeerExchange.Node != nil {
+			logger.Info("retrieving peer info via peer exchange protocol")
+
+			peerId, err := wakuNode.AddPeer(*options.PeerExchange.Node, string(peer_exchange.PeerExchangeID_v20alpha1))
+			if err != nil {
+				logger.Error("adding peer exchange peer", logging.MultiAddrs("node", *options.PeerExchange.Node), zap.Error(err))
+			} else {
+				desiredOutDegree := 6 // TODO: obtain this from gossipsub D
+				if err = wakuNode.PeerExchange().Request(ctx, desiredOutDegree, peer_exchange.WithPeer(*peerId)); err != nil {
+					logger.Error("requesting peers via peer exchange", zap.Error(err))
+				}
+			}
+		}
 	}
 
 	if len(options.Relay.Topics.Value()) == 0 {

waku/options.go

@@ -131,6 +131,12 @@ type WSOptions struct {
 	CertPath string
 }
 
+// PeerExchangeOptions are settings used with the peer exchange protocol
+type PeerExchangeOptions struct {
+	Enable bool
+	Node   *multiaddr.Multiaddr
+}
+
 // Options contains all the available features and settings that can be
 // configured via flags when executing go-waku as a service.
 type Options struct {
@@ -156,6 +162,7 @@ type Options struct {
 	PersistPeers     bool
 	UserAgent        string
 
+	PeerExchange PeerExchangeOptions
 	Websocket    WSOptions
 	Relay        RelayOptions
 	Store        StoreOptions

waku/v2/discv5/discover.go

@@ -21,7 +21,7 @@ import (
 )
 
 type DiscoveryV5 struct {
-	sync.Mutex
+	sync.RWMutex
 
 	discovery.Discovery
 
@@ -33,6 +33,7 @@ type DiscoveryV5 struct {
 	localnode *enode.LocalNode
 	NAT       nat.Interface
 	quit      chan struct{}
+	started   bool
 
 	log *zap.Logger
 
@@ -43,13 +44,14 @@ type DiscoveryV5 struct {
 
 type peerCache struct {
 	sync.RWMutex
-	recs map[peer.ID]peerRecord
+	recs map[peer.ID]PeerRecord
 	rng  *rand.Rand
 }
 
-type peerRecord struct {
+type PeerRecord struct {
 	expire int64
-	peer   peer.AddrInfo
+	Peer   peer.AddrInfo
+	Node   enode.Node
 }
 
 type discV5Parameters struct {
@@ -115,7 +117,7 @@ func NewDiscoveryV5(host host.Host, priv *ecdsa.PrivateKey, localnode *enode.Loc
 		wg:     &sync.WaitGroup{},
 		peerCache: peerCache{
 			rng:  rand.New(rand.NewSource(rand.Int63())),
-			recs: make(map[peer.ID]peerRecord),
+			recs: make(map[peer.ID]PeerRecord),
 		},
 		localnode: localnode,
 		config: discover.Config{
@@ -137,6 +139,10 @@ func NewDiscoveryV5(host host.Host, priv *ecdsa.PrivateKey, localnode *enode.Loc
 	}, nil
 }
 
+func (d *DiscoveryV5) Node() *enode.Node {
+	return d.localnode.Node()
+}
+
 func (d *DiscoveryV5) listen() error {
 	conn, err := net.ListenUDP("udp", d.udpAddr)
 	if err != nil {
@@ -174,9 +180,14 @@ func (d *DiscoveryV5) Start() error {
 	d.Lock()
 	defer d.Unlock()
 
+	if d.started {
+		return nil
+	}
+
 	d.wg.Wait() // Waiting for other go routines to stop
 
 	d.quit = make(chan struct{}, 1)
+	d.started = true
 
 	err := d.listen()
 	if err != nil {
@@ -190,10 +201,15 @@ func (d *DiscoveryV5) Stop() {
 	d.Lock()
 	defer d.Unlock()
 
+	if !d.started {
+		return
+	}
+
 	close(d.quit)
 
 	d.listener.Close()
 	d.listener = nil
+	d.started = false
 
 	d.log.Info("stopped Discovery V5")
 
@@ -293,9 +309,10 @@ func (d *DiscoveryV5) iterate(ctx context.Context, iterator enode.Iterator, limi
 		}
 
 		for _, p := range peerAddrs {
-			d.peerCache.recs[p.ID] = peerRecord{
+			d.peerCache.recs[p.ID] = PeerRecord{
 				expire: time.Now().Unix() + 3600, // Expires in 1hr
-				peer:   p,
+				Peer:   p,
+				Node:   *iterator.Node(),
 			}
 		}
 
@@ -320,7 +337,7 @@ func (d *DiscoveryV5) removeExpiredPeers() int {
 	return newCacheSize
 }
 
-func (d *DiscoveryV5) FindPeers(ctx context.Context, topic string, opts ...discovery.Option) (<-chan peer.AddrInfo, error) {
+func (d *DiscoveryV5) FindNodes(ctx context.Context, topic string, opts ...discovery.Option) ([]PeerRecord, error) {
 	// Get options
 	var options discovery.Options
 	err := options.Apply(opts...)
@@ -328,7 +345,7 @@ func (d *DiscoveryV5) FindPeers(ctx context.Context, topic string, opts ...disco
 		return nil, err
 	}
 
-	const maxLimit = 100
+	const maxLimit = 600
 	limit := options.Limit
 	if limit == 0 || limit > maxLimit {
 		limit = maxLimit
@@ -368,29 +385,43 @@ func (d *DiscoveryV5) FindPeers(ctx context.Context, topic string, opts ...disco
 		count = limit
 	}
 
-	chPeer := make(chan peer.AddrInfo, count)
-
 	perm := d.peerCache.rng.Perm(len(d.peerCache.recs))[0:count]
 	permSet := make(map[int]int)
 	for i, v := range perm {
 		permSet[v] = i
 	}
 
-	sendLst := make([]*peer.AddrInfo, count)
+	sendLst := make([]PeerRecord, count)
 	iter := 0
 	for k := range d.peerCache.recs {
 		if sendIndex, ok := permSet[iter]; ok {
-			peerInfo := d.peerCache.recs[k].peer
+			sendLst[sendIndex] = d.peerCache.recs[k]
-			sendLst[sendIndex] = &peerInfo
 		}
 		iter++
 	}
 
-	for _, send := range sendLst {
+	return sendLst, err
-		chPeer <- *send
+}
+
+func (d *DiscoveryV5) FindPeers(ctx context.Context, topic string, opts ...discovery.Option) (<-chan peer.AddrInfo, error) {
+	records, err := d.FindNodes(ctx, topic, opts...)
+	if err != nil {
+		return nil, err
+	}
+
+	chPeer := make(chan peer.AddrInfo, len(records))
+	for _, r := range records {
+		chPeer <- r.Peer
 	}
 
 	close(chPeer)
 
 	return chPeer, err
 }
+
+func (d *DiscoveryV5) IsStarted() bool {
+	d.RLock()
+	defer d.RUnlock()
+
+	return d.started
+}

waku/v2/metrics/metrics.go

@@ -18,6 +18,7 @@ var (
 	FilterSubscriptions = stats.Int64("filter_subscriptions", "Number of filter subscriptions", stats.UnitDimensionless)
 	StoreErrors         = stats.Int64("errors", "Number of errors in store protocol", stats.UnitDimensionless)
 	LightpushErrors     = stats.Int64("errors", "Number of errors in lightpush protocol", stats.UnitDimensionless)
+	PeerExchangeError   = stats.Int64("errors", "Number of errors in peer exchange protocol", stats.UnitDimensionless)
 )
 
 var (
@@ -79,6 +80,12 @@ func RecordLightpushError(ctx context.Context, tagType string) {
 	}
 }
 
+func RecordPeerExchangeError(ctx context.Context, tagType string) {
+	if err := stats.RecordWithTags(ctx, []tag.Mutator{tag.Insert(ErrorType, tagType)}, PeerExchangeError.M(1)); err != nil {
+		utils.Logger().Error("failed to record with tags", zap.Error(err))
+	}
+}
+
 func RecordMessage(ctx context.Context, tagType string, len int) {
 	if err := stats.RecordWithTags(ctx, []tag.Mutator{tag.Insert(KeyType, tagType)}, StoreMessages.M(int64(len))); err != nil {
 		utils.Logger().Error("failed to record with tags", zap.Error(err))

waku/v2/node/wakunode2.go

@@ -32,6 +32,7 @@ import (
 	"github.com/status-im/go-waku/waku/v2/protocol/filter"
 	"github.com/status-im/go-waku/waku/v2/protocol/lightpush"
 	"github.com/status-im/go-waku/waku/v2/protocol/pb"
+	"github.com/status-im/go-waku/waku/v2/protocol/peer_exchange"
 	"github.com/status-im/go-waku/waku/v2/protocol/relay"
 	"github.com/status-im/go-waku/waku/v2/protocol/store"
 	"github.com/status-im/go-waku/waku/v2/protocol/swap"
@@ -79,6 +80,7 @@ type WakuNode struct {
 	addrChan chan ma.Multiaddr
 
 	discoveryV5  *discv5.DiscoveryV5
+	peerExchange *peer_exchange.WakuPeerExchange
 
 	bcaster v2.Broadcaster
 
@@ -291,6 +293,13 @@ func (w *WakuNode) Start() error {
 		}
 	}
 
+	if w.opts.enablePeerExchange {
+		err := w.mountPeerExchange()
+		if err != nil {
+			return err
+		}
+	}
+
 	if w.opts.enableDiscV5 {
 		w.opts.wOpts = append(w.opts.wOpts, pubsub.WithDiscovery(w.discoveryV5, w.opts.discV5Opts...))
 	}
@@ -345,6 +354,14 @@ func (w *WakuNode) Stop() {
 		w.filter.Stop()
 	}
 
+	if w.peerExchange != nil {
+		w.peerExchange.Stop()
+	}
+
+	if w.discoveryV5 != nil {
+		w.discoveryV5.Stop()
+	}
+
 	w.relay.Stop()
 	w.lightPush.Stop()
 	w.store.Stop()
@@ -405,6 +422,11 @@ func (w *WakuNode) DiscV5() *discv5.DiscoveryV5 {
 	return w.discoveryV5
 }
 
+// PeerExchange is used to access any operation related to Peer Exchange
+func (w *WakuNode) PeerExchange() *peer_exchange.WakuPeerExchange {
+	return w.peerExchange
+}
+
 // Broadcaster is used to access the message broadcaster that is used to push
 // messages to different protocols
 func (w *WakuNode) Broadcaster() v2.Broadcaster {
@@ -474,6 +496,11 @@ func (w *WakuNode) mountDiscV5() error {
 	return err
 }
 
+func (w *WakuNode) mountPeerExchange() error {
+	w.peerExchange = peer_exchange.NewWakuPeerExchange(w.ctx, w.host, w.discoveryV5, w.log)
+	return w.peerExchange.Start()
+}
+
 func (w *WakuNode) startStore() {
 	w.store.Start(w.ctx)
 

waku/v2/node/wakuoptions.go

@@ -77,6 +77,8 @@ type WakuNodeParameters struct {
 	discV5Opts       []pubsub.DiscoverOpt
 	discV5autoUpdate bool
 
+	enablePeerExchange bool
+
 	enableRLN                    bool
 	rlnRelayMemIndex             uint
 	rlnRelayPubsubTopic          string
@@ -277,6 +279,14 @@ func WithDiscoveryV5(udpPort int, bootnodes []*enode.Node, autoUpdate bool, disc
 	}
 }
 
+// WithPeerExchange is a WakuOption used to enable Peer Exchange
+func WithPeerExchange() WakuNodeOption {
+	return func(params *WakuNodeParameters) error {
+		params.enablePeerExchange = true
+		return nil
+	}
+}
+
 // WithWakuFilter enables the Waku V2 Filter protocol. This WakuNodeOption
 // accepts a list of WakuFilter gossipsub options to setup the protocol
 func WithWakuFilter(fullNode bool, filterOpts ...filter.Option) WakuNodeOption {

waku/v2/protocol/pb/generate.go

@@ -5,3 +5,4 @@ package pb
 //go:generate protoc -I. --gofast_out=. ./waku_message.proto
 //go:generate protoc -I. --gofast_out=. ./waku_store.proto
 //go:generate protoc -I. --gofast_out=. ./waku_swap.proto
+//go:generate protoc -I. --gofast_out=. ./waku_peer_exchange.proto

waku/v2/protocol/pb/waku_peer_exchange.pb.go

@@ -0,0 +1,938 @@
+// Code generated by protoc-gen-gogo. DO NOT EDIT.
+// source: waku_peer_exchange.proto
+
+package pb
+
+import (
+	fmt "fmt"
+	proto "github.com/golang/protobuf/proto"
+	io "io"
+	math "math"
+	math_bits "math/bits"
+)
+
+// Reference imports to suppress errors if they are not otherwise used.
+var _ = proto.Marshal
+var _ = fmt.Errorf
+var _ = math.Inf
+
+// This is a compile-time assertion to ensure that this generated file
+// is compatible with the proto package it is being compiled against.
+// A compilation error at this line likely means your copy of the
+// proto package needs to be updated.
+const _ = proto.ProtoPackageIsVersion3 // please upgrade the proto package
+
+type PeerInfo struct {
+	ENR                  []byte   `protobuf:"bytes,1,opt,name=ENR,proto3" json:"ENR,omitempty"`
+	XXX_NoUnkeyedLiteral struct{} `json:"-"`
+	XXX_unrecognized     []byte   `json:"-"`
+	XXX_sizecache        int32    `json:"-"`
+}
+
+func (m *PeerInfo) Reset()         { *m = PeerInfo{} }
+func (m *PeerInfo) String() string { return proto.CompactTextString(m) }
+func (*PeerInfo) ProtoMessage()    {}
+func (*PeerInfo) Descriptor() ([]byte, []int) {
+	return fileDescriptor_ce50192ba54b780f, []int{0}
+}
+func (m *PeerInfo) XXX_Unmarshal(b []byte) error {
+	return m.Unmarshal(b)
+}
+func (m *PeerInfo) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
+	if deterministic {
+		return xxx_messageInfo_PeerInfo.Marshal(b, m, deterministic)
+	} else {
+		b = b[:cap(b)]
+		n, err := m.MarshalToSizedBuffer(b)
+		if err != nil {
+			return nil, err
+		}
+		return b[:n], nil
+	}
+}
+func (m *PeerInfo) XXX_Merge(src proto.Message) {
+	xxx_messageInfo_PeerInfo.Merge(m, src)
+}
+func (m *PeerInfo) XXX_Size() int {
+	return m.Size()
+}
+func (m *PeerInfo) XXX_DiscardUnknown() {
+	xxx_messageInfo_PeerInfo.DiscardUnknown(m)
+}
+
+var xxx_messageInfo_PeerInfo proto.InternalMessageInfo
+
+func (m *PeerInfo) GetENR() []byte {
+	if m != nil {
+		return m.ENR
+	}
+	return nil
+}
+
+type PeerExchangeQuery struct {
+	NumPeers             uint64   `protobuf:"varint,1,opt,name=numPeers,proto3" json:"numPeers,omitempty"`
+	XXX_NoUnkeyedLiteral struct{} `json:"-"`
+	XXX_unrecognized     []byte   `json:"-"`
+	XXX_sizecache        int32    `json:"-"`
+}
+
+func (m *PeerExchangeQuery) Reset()         { *m = PeerExchangeQuery{} }
+func (m *PeerExchangeQuery) String() string { return proto.CompactTextString(m) }
+func (*PeerExchangeQuery) ProtoMessage()    {}
+func (*PeerExchangeQuery) Descriptor() ([]byte, []int) {
+	return fileDescriptor_ce50192ba54b780f, []int{1}
+}
+func (m *PeerExchangeQuery) XXX_Unmarshal(b []byte) error {
+	return m.Unmarshal(b)
+}
+func (m *PeerExchangeQuery) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
+	if deterministic {
+		return xxx_messageInfo_PeerExchangeQuery.Marshal(b, m, deterministic)
+	} else {
+		b = b[:cap(b)]
+		n, err := m.MarshalToSizedBuffer(b)
+		if err != nil {
+			return nil, err
+		}
+		return b[:n], nil
+	}
+}
+func (m *PeerExchangeQuery) XXX_Merge(src proto.Message) {
+	xxx_messageInfo_PeerExchangeQuery.Merge(m, src)
+}
+func (m *PeerExchangeQuery) XXX_Size() int {
+	return m.Size()
+}
+func (m *PeerExchangeQuery) XXX_DiscardUnknown() {
+	xxx_messageInfo_PeerExchangeQuery.DiscardUnknown(m)
+}
+
+var xxx_messageInfo_PeerExchangeQuery proto.InternalMessageInfo
+
+func (m *PeerExchangeQuery) GetNumPeers() uint64 {
+	if m != nil {
+		return m.NumPeers
+	}
+	return 0
+}
+
+type PeerExchangeResponse struct {
+	PeerInfos            []*PeerInfo `protobuf:"bytes,1,rep,name=peerInfos,proto3" json:"peerInfos,omitempty"`
+	XXX_NoUnkeyedLiteral struct{}    `json:"-"`
+	XXX_unrecognized     []byte      `json:"-"`
+	XXX_sizecache        int32       `json:"-"`
+}
+
+func (m *PeerExchangeResponse) Reset()         { *m = PeerExchangeResponse{} }
+func (m *PeerExchangeResponse) String() string { return proto.CompactTextString(m) }
+func (*PeerExchangeResponse) ProtoMessage()    {}
+func (*PeerExchangeResponse) Descriptor() ([]byte, []int) {
+	return fileDescriptor_ce50192ba54b780f, []int{2}
+}
+func (m *PeerExchangeResponse) XXX_Unmarshal(b []byte) error {
+	return m.Unmarshal(b)
+}
+func (m *PeerExchangeResponse) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
+	if deterministic {
+		return xxx_messageInfo_PeerExchangeResponse.Marshal(b, m, deterministic)
+	} else {
+		b = b[:cap(b)]
+		n, err := m.MarshalToSizedBuffer(b)
+		if err != nil {
+			return nil, err
+		}
+		return b[:n], nil
+	}
+}
+func (m *PeerExchangeResponse) XXX_Merge(src proto.Message) {
+	xxx_messageInfo_PeerExchangeResponse.Merge(m, src)
+}
+func (m *PeerExchangeResponse) XXX_Size() int {
+	return m.Size()
+}
+func (m *PeerExchangeResponse) XXX_DiscardUnknown() {
+	xxx_messageInfo_PeerExchangeResponse.DiscardUnknown(m)
+}
+
+var xxx_messageInfo_PeerExchangeResponse proto.InternalMessageInfo
+
+func (m *PeerExchangeResponse) GetPeerInfos() []*PeerInfo {
+	if m != nil {
+		return m.PeerInfos
+	}
+	return nil
+}
+
+type PeerExchangeRPC struct {
+	Query                *PeerExchangeQuery    `protobuf:"bytes,1,opt,name=query,proto3" json:"query,omitempty"`
+	Response             *PeerExchangeResponse `protobuf:"bytes,2,opt,name=response,proto3" json:"response,omitempty"`
+	XXX_NoUnkeyedLiteral struct{}              `json:"-"`
+	XXX_unrecognized     []byte                `json:"-"`
+	XXX_sizecache        int32                 `json:"-"`
+}
+
+func (m *PeerExchangeRPC) Reset()         { *m = PeerExchangeRPC{} }
+func (m *PeerExchangeRPC) String() string { return proto.CompactTextString(m) }
+func (*PeerExchangeRPC) ProtoMessage()    {}
+func (*PeerExchangeRPC) Descriptor() ([]byte, []int) {
+	return fileDescriptor_ce50192ba54b780f, []int{3}
+}
+func (m *PeerExchangeRPC) XXX_Unmarshal(b []byte) error {
+	return m.Unmarshal(b)
+}
+func (m *PeerExchangeRPC) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
+	if deterministic {
+		return xxx_messageInfo_PeerExchangeRPC.Marshal(b, m, deterministic)
+	} else {
+		b = b[:cap(b)]
+		n, err := m.MarshalToSizedBuffer(b)
+		if err != nil {
+			return nil, err
+		}
+		return b[:n], nil
+	}
+}
+func (m *PeerExchangeRPC) XXX_Merge(src proto.Message) {
+	xxx_messageInfo_PeerExchangeRPC.Merge(m, src)
+}
+func (m *PeerExchangeRPC) XXX_Size() int {
+	return m.Size()
+}
+func (m *PeerExchangeRPC) XXX_DiscardUnknown() {
+	xxx_messageInfo_PeerExchangeRPC.DiscardUnknown(m)
+}
+
+var xxx_messageInfo_PeerExchangeRPC proto.InternalMessageInfo
+
+func (m *PeerExchangeRPC) GetQuery() *PeerExchangeQuery {
+	if m != nil {
+		return m.Query
+	}
+	return nil
+}
+
+func (m *PeerExchangeRPC) GetResponse() *PeerExchangeResponse {
+	if m != nil {
+		return m.Response
+	}
+	return nil
+}
+
+func init() {
+	proto.RegisterType((*PeerInfo)(nil), "PeerInfo")
+	proto.RegisterType((*PeerExchangeQuery)(nil), "PeerExchangeQuery")
+	proto.RegisterType((*PeerExchangeResponse)(nil), "PeerExchangeResponse")
+	proto.RegisterType((*PeerExchangeRPC)(nil), "PeerExchangeRPC")
+}
+
+func init() { proto.RegisterFile("waku_peer_exchange.proto", fileDescriptor_ce50192ba54b780f) }
+
+var fileDescriptor_ce50192ba54b780f = []byte{
+	// 211 bytes of a gzipped FileDescriptorProto
+	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0xe2, 0x92, 0x28, 0x4f, 0xcc, 0x2e,
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+	0x01, 0xd4, 0x1a, 0x90, 0x26, 0x66, 0x0d, 0x6e, 0x23, 0x4e, 0x3d, 0x98, 0xc5, 0x41, 0x08, 0x39,
+	0xa5, 0x3c, 0x2e, 0x7e, 0x14, 0x03, 0x02, 0x9c, 0x85, 0x34, 0xb8, 0x58, 0x0b, 0x41, 0x16, 0x83,
+	0x2d, 0xe3, 0x36, 0x12, 0xd2, 0xc3, 0x70, 0x52, 0x10, 0x44, 0x81, 0x90, 0x21, 0x17, 0x47, 0x11,
+	0xd4, 0x46, 0x09, 0x26, 0xb0, 0x62, 0x51, 0x3d, 0x6c, 0xce, 0x09, 0x82, 0x2b, 0x73, 0x12, 0x38,
+	0xf1, 0x48, 0x8e, 0xf1, 0xc2, 0x23, 0x39, 0xc6, 0x07, 0x8f, 0xe4, 0x18, 0x67, 0x3c, 0x96, 0x63,
+	0x48, 0x62, 0x03, 0x07, 0x8c, 0x31, 0x20, 0x00, 0x00, 0xff, 0xff, 0x99, 0xd5, 0xbb, 0xb6, 0x34,
+	0x01, 0x00, 0x00,
+}
+
+func (m *PeerInfo) Marshal() (dAtA []byte, err error) {
+	size := m.Size()
+	dAtA = make([]byte, size)
+	n, err := m.MarshalToSizedBuffer(dAtA[:size])
+	if err != nil {
+		return nil, err
+	}
+	return dAtA[:n], nil
+}
+
+func (m *PeerInfo) MarshalTo(dAtA []byte) (int, error) {
+	size := m.Size()
+	return m.MarshalToSizedBuffer(dAtA[:size])
+}
+
+func (m *PeerInfo) MarshalToSizedBuffer(dAtA []byte) (int, error) {
+	i := len(dAtA)
+	_ = i
+	var l int
+	_ = l
+	if m.XXX_unrecognized != nil {
+		i -= len(m.XXX_unrecognized)
+		copy(dAtA[i:], m.XXX_unrecognized)
+	}
+	if len(m.ENR) > 0 {
+		i -= len(m.ENR)
+		copy(dAtA[i:], m.ENR)
+		i = encodeVarintWakuPeerExchange(dAtA, i, uint64(len(m.ENR)))
+		i--
+		dAtA[i] = 0xa
+	}
+	return len(dAtA) - i, nil
+}
+
+func (m *PeerExchangeQuery) Marshal() (dAtA []byte, err error) {
+	size := m.Size()
+	dAtA = make([]byte, size)
+	n, err := m.MarshalToSizedBuffer(dAtA[:size])
+	if err != nil {
+		return nil, err
+	}
+	return dAtA[:n], nil
+}
+
+func (m *PeerExchangeQuery) MarshalTo(dAtA []byte) (int, error) {
+	size := m.Size()
+	return m.MarshalToSizedBuffer(dAtA[:size])
+}
+
+func (m *PeerExchangeQuery) MarshalToSizedBuffer(dAtA []byte) (int, error) {
+	i := len(dAtA)
+	_ = i
+	var l int
+	_ = l
+	if m.XXX_unrecognized != nil {
+		i -= len(m.XXX_unrecognized)
+		copy(dAtA[i:], m.XXX_unrecognized)
+	}
+	if m.NumPeers != 0 {
+		i = encodeVarintWakuPeerExchange(dAtA, i, uint64(m.NumPeers))
+		i--
+		dAtA[i] = 0x8
+	}
+	return len(dAtA) - i, nil
+}
+
+func (m *PeerExchangeResponse) Marshal() (dAtA []byte, err error) {
+	size := m.Size()
+	dAtA = make([]byte, size)
+	n, err := m.MarshalToSizedBuffer(dAtA[:size])
+	if err != nil {
+		return nil, err
+	}
+	return dAtA[:n], nil
+}
+
+func (m *PeerExchangeResponse) MarshalTo(dAtA []byte) (int, error) {
+	size := m.Size()
+	return m.MarshalToSizedBuffer(dAtA[:size])
+}
+
+func (m *PeerExchangeResponse) MarshalToSizedBuffer(dAtA []byte) (int, error) {
+	i := len(dAtA)
+	_ = i
+	var l int
+	_ = l
+	if m.XXX_unrecognized != nil {
+		i -= len(m.XXX_unrecognized)
+		copy(dAtA[i:], m.XXX_unrecognized)
+	}
+	if len(m.PeerInfos) > 0 {
+		for iNdEx := len(m.PeerInfos) - 1; iNdEx >= 0; iNdEx-- {
+			{
+				size, err := m.PeerInfos[iNdEx].MarshalToSizedBuffer(dAtA[:i])
+				if err != nil {
+					return 0, err
+				}
+				i -= size
+				i = encodeVarintWakuPeerExchange(dAtA, i, uint64(size))
+			}
+			i--
+			dAtA[i] = 0xa
+		}
+	}
+	return len(dAtA) - i, nil
+}
+
+func (m *PeerExchangeRPC) Marshal() (dAtA []byte, err error) {
+	size := m.Size()
+	dAtA = make([]byte, size)
+	n, err := m.MarshalToSizedBuffer(dAtA[:size])
+	if err != nil {
+		return nil, err
+	}
+	return dAtA[:n], nil
+}
+
+func (m *PeerExchangeRPC) MarshalTo(dAtA []byte) (int, error) {
+	size := m.Size()
+	return m.MarshalToSizedBuffer(dAtA[:size])
+}
+
+func (m *PeerExchangeRPC) MarshalToSizedBuffer(dAtA []byte) (int, error) {
+	i := len(dAtA)
+	_ = i
+	var l int
+	_ = l
+	if m.XXX_unrecognized != nil {
+		i -= len(m.XXX_unrecognized)
+		copy(dAtA[i:], m.XXX_unrecognized)
+	}
+	if m.Response != nil {
+		{
+			size, err := m.Response.MarshalToSizedBuffer(dAtA[:i])
+			if err != nil {
+				return 0, err
+			}
+			i -= size
+			i = encodeVarintWakuPeerExchange(dAtA, i, uint64(size))
+		}
+		i--
+		dAtA[i] = 0x12
+	}
+	if m.Query != nil {
+		{
+			size, err := m.Query.MarshalToSizedBuffer(dAtA[:i])
+			if err != nil {
+				return 0, err
+			}
+			i -= size
+			i = encodeVarintWakuPeerExchange(dAtA, i, uint64(size))
+		}
+		i--
+		dAtA[i] = 0xa
+	}
+	return len(dAtA) - i, nil
+}
+
+func encodeVarintWakuPeerExchange(dAtA []byte, offset int, v uint64) int {
+	offset -= sovWakuPeerExchange(v)
+	base := offset
+	for v >= 1<<7 {
+		dAtA[offset] = uint8(v&0x7f | 0x80)
+		v >>= 7
+		offset++
+	}
+	dAtA[offset] = uint8(v)
+	return base
+}
+func (m *PeerInfo) Size() (n int) {
+	if m == nil {
+		return 0
+	}
+	var l int
+	_ = l
+	l = len(m.ENR)
+	if l > 0 {
+		n += 1 + l + sovWakuPeerExchange(uint64(l))
+	}
+	if m.XXX_unrecognized != nil {
+		n += len(m.XXX_unrecognized)
+	}
+	return n
+}
+
+func (m *PeerExchangeQuery) Size() (n int) {
+	if m == nil {
+		return 0
+	}
+	var l int
+	_ = l
+	if m.NumPeers != 0 {
+		n += 1 + sovWakuPeerExchange(uint64(m.NumPeers))
+	}
+	if m.XXX_unrecognized != nil {
+		n += len(m.XXX_unrecognized)
+	}
+	return n
+}
+
+func (m *PeerExchangeResponse) Size() (n int) {
+	if m == nil {
+		return 0
+	}
+	var l int
+	_ = l
+	if len(m.PeerInfos) > 0 {
+		for _, e := range m.PeerInfos {
+			l = e.Size()
+			n += 1 + l + sovWakuPeerExchange(uint64(l))
+		}
+	}
+	if m.XXX_unrecognized != nil {
+		n += len(m.XXX_unrecognized)
+	}
+	return n
+}
+
+func (m *PeerExchangeRPC) Size() (n int) {
+	if m == nil {
+		return 0
+	}
+	var l int
+	_ = l
+	if m.Query != nil {
+		l = m.Query.Size()
+		n += 1 + l + sovWakuPeerExchange(uint64(l))
+	}
+	if m.Response != nil {
+		l = m.Response.Size()
+		n += 1 + l + sovWakuPeerExchange(uint64(l))
+	}
+	if m.XXX_unrecognized != nil {
+		n += len(m.XXX_unrecognized)
+	}
+	return n
+}
+
+func sovWakuPeerExchange(x uint64) (n int) {
+	return (math_bits.Len64(x|1) + 6) / 7
+}
+func sozWakuPeerExchange(x uint64) (n int) {
+	return sovWakuPeerExchange(uint64((x << 1) ^ uint64((int64(x) >> 63))))
+}
+func (m *PeerInfo) Unmarshal(dAtA []byte) error {
+	l := len(dAtA)
+	iNdEx := 0
+	for iNdEx < l {
+		preIndex := iNdEx
+		var wire uint64
+		for shift := uint(0); ; shift += 7 {
+			if shift >= 64 {
+				return ErrIntOverflowWakuPeerExchange
+			}
+			if iNdEx >= l {
+				return io.ErrUnexpectedEOF
+			}
+			b := dAtA[iNdEx]
+			iNdEx++
+			wire |= uint64(b&0x7F) << shift
+			if b < 0x80 {
+				break
+			}
+		}
+		fieldNum := int32(wire >> 3)
+		wireType := int(wire & 0x7)
+		if wireType == 4 {
+			return fmt.Errorf("proto: PeerInfo: wiretype end group for non-group")
+		}
+		if fieldNum <= 0 {
+			return fmt.Errorf("proto: PeerInfo: illegal tag %d (wire type %d)", fieldNum, wire)
+		}
+		switch fieldNum {
+		case 1:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field ENR", wireType)
+			}
+			var byteLen int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowWakuPeerExchange
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				byteLen |= int(b&0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			if byteLen < 0 {
+				return ErrInvalidLengthWakuPeerExchange
+			}
+			postIndex := iNdEx + byteLen
+			if postIndex < 0 {
+				return ErrInvalidLengthWakuPeerExchange
+			}
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			m.ENR = append(m.ENR[:0], dAtA[iNdEx:postIndex]...)
+			if m.ENR == nil {
+				m.ENR = []byte{}
+			}
+			iNdEx = postIndex
+		default:
+			iNdEx = preIndex
+			skippy, err := skipWakuPeerExchange(dAtA[iNdEx:])
+			if err != nil {
+				return err
+			}
+			if (skippy < 0) || (iNdEx+skippy) < 0 {
+				return ErrInvalidLengthWakuPeerExchange
+			}
+			if (iNdEx + skippy) > l {
+				return io.ErrUnexpectedEOF
+			}
+			m.XXX_unrecognized = append(m.XXX_unrecognized, dAtA[iNdEx:iNdEx+skippy]...)
+			iNdEx += skippy
+		}
+	}
+
+	if iNdEx > l {
+		return io.ErrUnexpectedEOF
+	}
+	return nil
+}
+func (m *PeerExchangeQuery) Unmarshal(dAtA []byte) error {
+	l := len(dAtA)
+	iNdEx := 0
+	for iNdEx < l {
+		preIndex := iNdEx
+		var wire uint64
+		for shift := uint(0); ; shift += 7 {
+			if shift >= 64 {
+				return ErrIntOverflowWakuPeerExchange
+			}
+			if iNdEx >= l {
+				return io.ErrUnexpectedEOF
+			}
+			b := dAtA[iNdEx]
+			iNdEx++
+			wire |= uint64(b&0x7F) << shift
+			if b < 0x80 {
+				break
+			}
+		}
+		fieldNum := int32(wire >> 3)
+		wireType := int(wire & 0x7)
+		if wireType == 4 {
+			return fmt.Errorf("proto: PeerExchangeQuery: wiretype end group for non-group")
+		}
+		if fieldNum <= 0 {
+			return fmt.Errorf("proto: PeerExchangeQuery: illegal tag %d (wire type %d)", fieldNum, wire)
+		}
+		switch fieldNum {
+		case 1:
+			if wireType != 0 {
+				return fmt.Errorf("proto: wrong wireType = %d for field NumPeers", wireType)
+			}
+			m.NumPeers = 0
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowWakuPeerExchange
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				m.NumPeers |= uint64(b&0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+		default:
+			iNdEx = preIndex
+			skippy, err := skipWakuPeerExchange(dAtA[iNdEx:])
+			if err != nil {
+				return err
+			}
+			if (skippy < 0) || (iNdEx+skippy) < 0 {
+				return ErrInvalidLengthWakuPeerExchange
+			}
+			if (iNdEx + skippy) > l {
+				return io.ErrUnexpectedEOF
+			}
+			m.XXX_unrecognized = append(m.XXX_unrecognized, dAtA[iNdEx:iNdEx+skippy]...)
+			iNdEx += skippy
+		}
+	}
+
+	if iNdEx > l {
+		return io.ErrUnexpectedEOF
+	}
+	return nil
+}
+func (m *PeerExchangeResponse) Unmarshal(dAtA []byte) error {
+	l := len(dAtA)
+	iNdEx := 0
+	for iNdEx < l {
+		preIndex := iNdEx
+		var wire uint64
+		for shift := uint(0); ; shift += 7 {
+			if shift >= 64 {
+				return ErrIntOverflowWakuPeerExchange
+			}
+			if iNdEx >= l {
+				return io.ErrUnexpectedEOF
+			}
+			b := dAtA[iNdEx]
+			iNdEx++
+			wire |= uint64(b&0x7F) << shift
+			if b < 0x80 {
+				break
+			}
+		}
+		fieldNum := int32(wire >> 3)
+		wireType := int(wire & 0x7)
+		if wireType == 4 {
+			return fmt.Errorf("proto: PeerExchangeResponse: wiretype end group for non-group")
+		}
+		if fieldNum <= 0 {
+			return fmt.Errorf("proto: PeerExchangeResponse: illegal tag %d (wire type %d)", fieldNum, wire)
+		}
+		switch fieldNum {
+		case 1:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field PeerInfos", wireType)
+			}
+			var msglen int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowWakuPeerExchange
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				msglen |= int(b&0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			if msglen < 0 {
+				return ErrInvalidLengthWakuPeerExchange
+			}
+			postIndex := iNdEx + msglen
+			if postIndex < 0 {
+				return ErrInvalidLengthWakuPeerExchange
+			}
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			m.PeerInfos = append(m.PeerInfos, &PeerInfo{})
+			if err := m.PeerInfos[len(m.PeerInfos)-1].Unmarshal(dAtA[iNdEx:postIndex]); err != nil {
+				return err
+			}
+			iNdEx = postIndex
+		default:
+			iNdEx = preIndex
+			skippy, err := skipWakuPeerExchange(dAtA[iNdEx:])
+			if err != nil {
+				return err
+			}
+			if (skippy < 0) || (iNdEx+skippy) < 0 {
+				return ErrInvalidLengthWakuPeerExchange
+			}
+			if (iNdEx + skippy) > l {
+				return io.ErrUnexpectedEOF
+			}
+			m.XXX_unrecognized = append(m.XXX_unrecognized, dAtA[iNdEx:iNdEx+skippy]...)
+			iNdEx += skippy
+		}
+	}
+
+	if iNdEx > l {
+		return io.ErrUnexpectedEOF
+	}
+	return nil
+}
+func (m *PeerExchangeRPC) Unmarshal(dAtA []byte) error {
+	l := len(dAtA)
+	iNdEx := 0
+	for iNdEx < l {
+		preIndex := iNdEx
+		var wire uint64
+		for shift := uint(0); ; shift += 7 {
+			if shift >= 64 {
+				return ErrIntOverflowWakuPeerExchange
+			}
+			if iNdEx >= l {
+				return io.ErrUnexpectedEOF
+			}
+			b := dAtA[iNdEx]
+			iNdEx++
+			wire |= uint64(b&0x7F) << shift
+			if b < 0x80 {
+				break
+			}
+		}
+		fieldNum := int32(wire >> 3)
+		wireType := int(wire & 0x7)
+		if wireType == 4 {
+			return fmt.Errorf("proto: PeerExchangeRPC: wiretype end group for non-group")
+		}
+		if fieldNum <= 0 {
+			return fmt.Errorf("proto: PeerExchangeRPC: illegal tag %d (wire type %d)", fieldNum, wire)
+		}
+		switch fieldNum {
+		case 1:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Query", wireType)
+			}
+			var msglen int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowWakuPeerExchange
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				msglen |= int(b&0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			if msglen < 0 {
+				return ErrInvalidLengthWakuPeerExchange
+			}
+			postIndex := iNdEx + msglen
+			if postIndex < 0 {
+				return ErrInvalidLengthWakuPeerExchange
+			}
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			if m.Query == nil {
+				m.Query = &PeerExchangeQuery{}
+			}
+			if err := m.Query.Unmarshal(dAtA[iNdEx:postIndex]); err != nil {
+				return err
+			}
+			iNdEx = postIndex
+		case 2:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Response", wireType)
+			}
+			var msglen int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowWakuPeerExchange
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				msglen |= int(b&0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			if msglen < 0 {
+				return ErrInvalidLengthWakuPeerExchange
+			}
+			postIndex := iNdEx + msglen
+			if postIndex < 0 {
+				return ErrInvalidLengthWakuPeerExchange
+			}
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			if m.Response == nil {
+				m.Response = &PeerExchangeResponse{}
+			}
+			if err := m.Response.Unmarshal(dAtA[iNdEx:postIndex]); err != nil {
+				return err
+			}
+			iNdEx = postIndex
+		default:
+			iNdEx = preIndex
+			skippy, err := skipWakuPeerExchange(dAtA[iNdEx:])
+			if err != nil {
+				return err
+			}
+			if (skippy < 0) || (iNdEx+skippy) < 0 {
+				return ErrInvalidLengthWakuPeerExchange
+			}
+			if (iNdEx + skippy) > l {
+				return io.ErrUnexpectedEOF
+			}
+			m.XXX_unrecognized = append(m.XXX_unrecognized, dAtA[iNdEx:iNdEx+skippy]...)
+			iNdEx += skippy
+		}
+	}
+
+	if iNdEx > l {
+		return io.ErrUnexpectedEOF
+	}
+	return nil
+}
+func skipWakuPeerExchange(dAtA []byte) (n int, err error) {
+	l := len(dAtA)
+	iNdEx := 0
+	depth := 0
+	for iNdEx < l {
+		var wire uint64
+		for shift := uint(0); ; shift += 7 {
+			if shift >= 64 {
+				return 0, ErrIntOverflowWakuPeerExchange
+			}
+			if iNdEx >= l {
+				return 0, io.ErrUnexpectedEOF
+			}
+			b := dAtA[iNdEx]
+			iNdEx++
+			wire |= (uint64(b) & 0x7F) << shift
+			if b < 0x80 {
+				break
+			}
+		}
+		wireType := int(wire & 0x7)
+		switch wireType {
+		case 0:
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return 0, ErrIntOverflowWakuPeerExchange
+				}
+				if iNdEx >= l {
+					return 0, io.ErrUnexpectedEOF
+				}
+				iNdEx++
+				if dAtA[iNdEx-1] < 0x80 {
+					break
+				}
+			}
+		case 1:
+			iNdEx += 8
+		case 2:
+			var length int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return 0, ErrIntOverflowWakuPeerExchange
+				}
+				if iNdEx >= l {
+					return 0, io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				length |= (int(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			if length < 0 {
+				return 0, ErrInvalidLengthWakuPeerExchange
+			}
+			iNdEx += length
+		case 3:
+			depth++
+		case 4:
+			if depth == 0 {
+				return 0, ErrUnexpectedEndOfGroupWakuPeerExchange
+			}
+			depth--
+		case 5:
+			iNdEx += 4
+		default:
+			return 0, fmt.Errorf("proto: illegal wireType %d", wireType)
+		}
+		if iNdEx < 0 {
+			return 0, ErrInvalidLengthWakuPeerExchange
+		}
+		if depth == 0 {
+			return iNdEx, nil
+		}
+	}
+	return 0, io.ErrUnexpectedEOF
+}
+
+var (
+	ErrInvalidLengthWakuPeerExchange        = fmt.Errorf("proto: negative length found during unmarshaling")
+	ErrIntOverflowWakuPeerExchange          = fmt.Errorf("proto: integer overflow")
+	ErrUnexpectedEndOfGroupWakuPeerExchange = fmt.Errorf("proto: unexpected end of group")
+)

waku/v2/protocol/pb/waku_peer_exchange.proto

@@ -0,0 +1,18 @@
+syntax = "proto3";
+
+message PeerInfo {
+  bytes ENR = 1;
+}
+
+message PeerExchangeQuery {
+  uint64 numPeers = 1; // number of peers requested
+}
+
+message PeerExchangeResponse {
+  repeated PeerInfo peerInfos = 1;
+}
+
+message PeerExchangeRPC {
+  PeerExchangeQuery query = 1;
+  PeerExchangeResponse response = 2;
+}

waku/v2/protocol/peer_exchange/waku_peer_exchange.go

@@ -0,0 +1,364 @@
+package peer_exchange
+
+import (
+	"bufio"
+	"bytes"
+	"context"
+	"errors"
+	"math"
+	"math/rand"
+	"sync"
+	"time"
+
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/p2p/enode"
+	"github.com/ethereum/go-ethereum/p2p/enr"
+	"github.com/ethereum/go-ethereum/rlp"
+	"github.com/libp2p/go-libp2p/core/host"
+	"github.com/libp2p/go-libp2p/core/network"
+	"github.com/libp2p/go-libp2p/core/peer"
+	libp2pProtocol "github.com/libp2p/go-libp2p/core/protocol"
+	"github.com/libp2p/go-msgio/protoio"
+	"github.com/status-im/go-waku/logging"
+	"github.com/status-im/go-waku/waku/v2/discv5"
+	"github.com/status-im/go-waku/waku/v2/metrics"
+	"github.com/status-im/go-waku/waku/v2/protocol"
+	"github.com/status-im/go-waku/waku/v2/protocol/pb"
+	"github.com/status-im/go-waku/waku/v2/utils"
+	"go.uber.org/zap"
+)
+
+// PeerExchangeID_v20alpha1 is the current Waku Peer Exchange protocol identifier
+const PeerExchangeID_v20alpha1 = libp2pProtocol.ID("/vac/waku/peer-exchange/2.0.0-alpha1")
+const MaxCacheSize = 1000
+const CacheCleanWindow = 200
+const dialTimeout = 7 * time.Second
+
+var (
+	ErrNoPeersAvailable = errors.New("no suitable remote peers")
+	ErrInvalidId        = errors.New("invalid request id")
+)
+
+type peerRecord struct {
+	node enode.Node
+	idx  int
+}
+
+type WakuPeerExchange struct {
+	h    host.Host
+	ctx  context.Context
+	disc *discv5.DiscoveryV5
+
+	log  *zap.Logger
+	quit chan struct{}
+	wg   sync.WaitGroup
+
+	enrCache      map[enode.ID]peerRecord // todo: next step: ring buffer; future: implement cache satisfying https://rfc.vac.dev/spec/34/
+	enrCacheMutex sync.RWMutex
+	rng           *rand.Rand
+
+	started bool
+}
+
+// NewWakuPeerExchange returns a new instance of WakuPeerExchange struct
+func NewWakuPeerExchange(ctx context.Context, h host.Host, disc *discv5.DiscoveryV5, log *zap.Logger) *WakuPeerExchange {
+	wakuPX := new(WakuPeerExchange)
+	wakuPX.ctx = ctx
+	wakuPX.h = h
+	wakuPX.disc = disc
+	wakuPX.log = log.Named("wakupx")
+	wakuPX.enrCache = make(map[enode.ID]peerRecord)
+	wakuPX.rng = rand.New(rand.NewSource(rand.Int63()))
+	return wakuPX
+}
+
+// Start inits the peer exchange protocol
+func (wakuPX *WakuPeerExchange) Start() error {
+	wakuPX.h.SetStreamHandlerMatch(PeerExchangeID_v20alpha1, protocol.PrefixTextMatch(string(PeerExchangeID_v20alpha1)), wakuPX.onRequest)
+	wakuPX.log.Info("Peer exchange protocol started")
+	wakuPX.started = true
+	wakuPX.quit = make(chan struct{}, 1)
+
+	wakuPX.wg.Add(1)
+	go wakuPX.runPeerExchangeDiscv5Loop()
+
+	return nil
+}
+
+func (wakuPX *WakuPeerExchange) handleResponse(response *pb.PeerExchangeResponse) error {
+	var peers []peer.AddrInfo
+	for _, p := range response.PeerInfos {
+		enrRecord := &enr.Record{}
+		buf := bytes.NewBuffer(p.ENR)
+
+		err := enrRecord.DecodeRLP(rlp.NewStream(buf, uint64(len(p.ENR))))
+		if err != nil {
+			wakuPX.log.Error("converting bytes to enr", zap.Error(err))
+			return err
+		}
+
+		enodeRecord, err := enode.New(enode.ValidSchemes, enrRecord)
+		if err != nil {
+			wakuPX.log.Error("creating enode record", zap.Error(err))
+
+			return err
+		}
+
+		peerInfo, err := utils.EnodeToPeerInfo(enodeRecord)
+		if err != nil {
+			return err
+		}
+
+		if wakuPX.h.Network().Connectedness(peerInfo.ID) != network.Connected {
+			peers = append(peers, *peerInfo)
+		}
+	}
+
+	if len(peers) != 0 {
+		log.Info("connecting to newly discovered peers", zap.Int("count", len(peers)))
+		for _, p := range peers {
+			func(p peer.AddrInfo) {
+				ctx, cancel := context.WithTimeout(wakuPX.ctx, dialTimeout)
+				defer cancel()
+				err := wakuPX.h.Connect(ctx, p)
+				if err != nil {
+					log.Info("connecting to peer", zap.String("peer", p.ID.Pretty()), zap.Error(err))
+				}
+			}(p)
+		}
+	}
+
+	return nil
+}
+
+func (wakuPX *WakuPeerExchange) onRequest(s network.Stream) {
+	defer s.Close()
+	logger := wakuPX.log.With(logging.HostID("peer", s.Conn().RemotePeer()))
+	requestRPC := &pb.PeerExchangeRPC{}
+	reader := protoio.NewDelimitedReader(s, math.MaxInt32)
+	err := reader.ReadMsg(requestRPC)
+	if err != nil {
+		logger.Error("reading request", zap.Error(err))
+		metrics.RecordPeerExchangeError(wakuPX.ctx, "decodeRpcFailure")
+		return
+	}
+
+	if requestRPC.Query != nil {
+		logger.Info("request received")
+		err := wakuPX.respond(requestRPC.Query.NumPeers, s.Conn().RemotePeer())
+		if err != nil {
+			logger.Error("responding", zap.Error(err))
+			metrics.RecordPeerExchangeError(wakuPX.ctx, "pxFailure")
+			return
+		}
+	}
+
+	if requestRPC.Response != nil {
+		logger.Info("response received")
+		err := wakuPX.handleResponse(requestRPC.Response)
+		if err != nil {
+			logger.Error("handling response", zap.Error(err))
+			metrics.RecordPeerExchangeError(wakuPX.ctx, "pxFailure")
+			return
+		}
+	}
+}
+
+func (wakuPX *WakuPeerExchange) Request(ctx context.Context, numPeers int, opts ...PeerExchangeOption) error {
+	params := new(PeerExchangeParameters)
+	params.host = wakuPX.h
+	params.log = wakuPX.log
+
+	optList := DefaultOptions(wakuPX.h)
+	optList = append(optList, opts...)
+	for _, opt := range optList {
+		opt(params)
+	}
+
+	if params.selectedPeer == "" {
+		metrics.RecordPeerExchangeError(wakuPX.ctx, "dialError")
+		return ErrNoPeersAvailable
+	}
+
+	requestRPC := &pb.PeerExchangeRPC{
+		Query: &pb.PeerExchangeQuery{
+			NumPeers: uint64(numPeers),
+		},
+	}
+
+	return wakuPX.sendPeerExchangeRPCToPeer(requestRPC, params.selectedPeer)
+}
+
+// IsStarted returns if the peer exchange protocol has been mounted or not
+func (wakuPX *WakuPeerExchange) IsStarted() bool {
+	return wakuPX.started
+}
+
+// Stop unmounts the peer exchange protocol
+func (wakuPX *WakuPeerExchange) Stop() {
+	if wakuPX.started {
+		wakuPX.h.RemoveStreamHandler(PeerExchangeID_v20alpha1)
+		wakuPX.started = false
+		close(wakuPX.quit)
+		wakuPX.wg.Wait()
+	}
+}
+
+func (wakuPX *WakuPeerExchange) sendPeerExchangeRPCToPeer(rpc *pb.PeerExchangeRPC, peerID peer.ID) error {
+	logger := wakuPX.log.With(logging.HostID("peer", peerID))
+
+	// We connect first so dns4 addresses are resolved (NewStream does not do it)
+	err := wakuPX.h.Connect(wakuPX.ctx, wakuPX.h.Peerstore().PeerInfo(peerID))
+	if err != nil {
+		logger.Error("connecting peer", zap.Error(err))
+		return err
+	}
+
+	connOpt, err := wakuPX.h.NewStream(wakuPX.ctx, peerID, PeerExchangeID_v20alpha1)
+	if err != nil {
+		logger.Error("creating stream to peer", zap.Error(err))
+		return err
+	}
+	defer connOpt.Close()
+
+	writer := protoio.NewDelimitedWriter(connOpt)
+	err = writer.WriteMsg(rpc)
+	if err != nil {
+		logger.Error("writing response", zap.Error(err))
+		return err
+	}
+
+	return nil
+}
+
+func (wakuPX *WakuPeerExchange) respond(numPeers uint64, peerID peer.ID) error {
+	records, err := wakuPX.getENRsFromCache(numPeers)
+	if err != nil {
+		return err
+	}
+
+	responseRPC := &pb.PeerExchangeRPC{}
+	responseRPC.Response = new(pb.PeerExchangeResponse)
+	responseRPC.Response.PeerInfos = records
+
+	return wakuPX.sendPeerExchangeRPCToPeer(responseRPC, peerID)
+}
+
+func (wakuPX *WakuPeerExchange) getENRsFromCache(numPeers uint64) ([]*pb.PeerInfo, error) {
+	wakuPX.enrCacheMutex.Lock()
+	defer wakuPX.enrCacheMutex.Unlock()
+
+	if len(wakuPX.enrCache) == 0 {
+		return nil, nil
+	}
+
+	numItems := int(numPeers)
+	if len(wakuPX.enrCache) < int(numPeers) {
+		numItems = len(wakuPX.enrCache)
+	}
+
+	perm := wakuPX.rng.Perm(len(wakuPX.enrCache))[0:numItems]
+	permSet := make(map[int]int)
+	for i, v := range perm {
+		permSet[v] = i
+	}
+
+	var result []*pb.PeerInfo
+	iter := 0
+	for k := range wakuPX.enrCache {
+		if _, ok := permSet[iter]; ok {
+			var b bytes.Buffer
+			writer := bufio.NewWriter(&b)
+			enode := wakuPX.enrCache[k]
+
+			err := enode.node.Record().EncodeRLP(writer)
+			if err != nil {
+				return nil, err
+			}
+
+			writer.Flush()
+
+			result = append(result, &pb.PeerInfo{
+				ENR: b.Bytes(),
+			})
+		}
+		iter++
+	}
+
+	return result, nil
+}
+
+func (wakuPX *WakuPeerExchange) cleanCache() {
+	if len(wakuPX.enrCache) < MaxCacheSize {
+		return
+	}
+
+	r := make(map[enode.ID]peerRecord)
+	for k, v := range wakuPX.enrCache {
+		if v.idx > CacheCleanWindow {
+			v.idx -= CacheCleanWindow
+			r[k] = v
+		}
+	}
+
+	wakuPX.enrCache = r
+}
+
+func (wakuPX *WakuPeerExchange) findPeers() {
+	if !wakuPX.disc.IsStarted() {
+		return
+	}
+
+	ctx, cancel := context.WithTimeout(wakuPX.ctx, 2*time.Second)
+	defer cancel()
+	peerRecords, err := wakuPX.disc.FindNodes(ctx, "")
+	if err != nil {
+		wakuPX.log.Error("finding peers", zap.Error(err))
+	}
+
+	cnt := 0
+	wakuPX.enrCacheMutex.Lock()
+	for _, p := range peerRecords {
+		cnt++
+		wakuPX.enrCache[p.Node.ID()] = peerRecord{
+			idx:  len(wakuPX.enrCache),
+			node: p.Node,
+		}
+	}
+	wakuPX.enrCacheMutex.Unlock()
+
+	wakuPX.log.Info("discovered px peers via discv5", zap.Int("count", cnt))
+
+	wakuPX.cleanCache()
+}
+
+func (wakuPX *WakuPeerExchange) runPeerExchangeDiscv5Loop() {
+	defer wakuPX.wg.Done()
+
+	// Runs a discv5 loop adding new peers to the px peer cache
+	if wakuPX.disc == nil {
+		wakuPX.log.Warn("trying to run discovery v5 (for PX) while it's disabled")
+		return
+	}
+
+	wakuPX.log.Info("starting peer exchange discovery v5 loop")
+
+	ticker := time.NewTicker(30 * time.Second)
+	defer ticker.Stop()
+
+	// This loop "competes" with the loop in wakunode2
+	// For the purpose of collecting px peers, 30 sec intervals should be enough
+
+	wakuPX.findPeers()
+
+	for {
+		select {
+		case <-wakuPX.quit:
+			return
+
+		case <-ticker.C:
+			wakuPX.findPeers()
+		}
+
+	}
+}

waku/v2/protocol/peer_exchange/waku_peer_exchange_option.go

@@ -0,0 +1,58 @@
+package peer_exchange
+
+import (
+	"context"
+
+	"github.com/libp2p/go-libp2p/core/host"
+	"github.com/libp2p/go-libp2p/core/peer"
+	"github.com/status-im/go-waku/waku/v2/utils"
+	"go.uber.org/zap"
+)
+
+type PeerExchangeParameters struct {
+	host         host.Host
+	selectedPeer peer.ID
+	log          *zap.Logger
+}
+
+type PeerExchangeOption func(*PeerExchangeParameters)
+
+// WithPeer is an option used to specify the peerID to push a waku message to
+func WithPeer(p peer.ID) PeerExchangeOption {
+	return func(params *PeerExchangeParameters) {
+		params.selectedPeer = p
+	}
+}
+
+// WithAutomaticPeerSelection is an option used to randomly select a peer from the peer store
+// to push a waku message to
+func WithAutomaticPeerSelection() PeerExchangeOption {
+	return func(params *PeerExchangeParameters) {
+		p, err := utils.SelectPeer(params.host, string(PeerExchangeID_v20alpha1), params.log)
+		if err == nil {
+			params.selectedPeer = *p
+		} else {
+			params.log.Info("selecting peer", zap.Error(err))
+		}
+	}
+}
+
+// WithFastestPeerSelection is an option used to select a peer from the peer store
+// with the lowest ping
+func WithFastestPeerSelection(ctx context.Context) PeerExchangeOption {
+	return func(params *PeerExchangeParameters) {
+		p, err := utils.SelectPeerWithLowestRTT(ctx, params.host, string(PeerExchangeID_v20alpha1), params.log)
+		if err == nil {
+			params.selectedPeer = *p
+		} else {
+			params.log.Info("selecting peer", zap.Error(err))
+		}
+	}
+}
+
+// DefaultOptions are the default options to be used when using the lightpush protocol
+func DefaultOptions(host host.Host) []PeerExchangeOption {
+	return []PeerExchangeOption{
+		WithAutomaticPeerSelection(),
+	}
+}

waku/v2/protocol/peer_exchange/waku_peer_exchange_test.go

@@ -0,0 +1,162 @@
+package peer_exchange
+
+import (
+	"context"
+	"crypto/ecdsa"
+	"fmt"
+	"math"
+	"net"
+	"strconv"
+	"testing"
+	"time"
+
+	gcrypto "github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/p2p/enode"
+	"github.com/ethereum/go-ethereum/p2p/enr"
+	"github.com/libp2p/go-libp2p"
+	"github.com/libp2p/go-libp2p/core/host"
+	"github.com/libp2p/go-libp2p/core/peerstore"
+	"github.com/multiformats/go-multiaddr"
+	"github.com/status-im/go-waku/tests"
+	"github.com/status-im/go-waku/waku/v2/discv5"
+	"github.com/status-im/go-waku/waku/v2/utils"
+	"github.com/stretchr/testify/require"
+	"go.uber.org/zap"
+
+	libp2pcrypto "github.com/libp2p/go-libp2p/core/crypto"
+)
+
+func createHost(t *testing.T) (host.Host, int, *ecdsa.PrivateKey) {
+	privKey, err := gcrypto.GenerateKey()
+	require.NoError(t, err)
+
+	sPrivKey := libp2pcrypto.PrivKey(utils.EcdsaPrivKeyToSecp256k1PrivKey(privKey))
+
+	port, err := tests.FindFreePort(t, "127.0.0.1", 3)
+	require.NoError(t, err)
+
+	sourceMultiAddr, err := multiaddr.NewMultiaddr(fmt.Sprintf("/ip4/127.0.0.1/tcp/%d", port))
+	require.NoError(t, err)
+
+	host, err := libp2p.New(
+		libp2p.ListenAddrs(sourceMultiAddr),
+		libp2p.Identity(sPrivKey),
+	)
+	require.NoError(t, err)
+
+	return host, port, privKey
+}
+
+func extractIP(addr multiaddr.Multiaddr) (*net.TCPAddr, error) {
+	ipStr, err := addr.ValueForProtocol(multiaddr.P_IP4)
+	if err != nil {
+		return nil, err
+	}
+
+	portStr, err := addr.ValueForProtocol(multiaddr.P_TCP)
+	if err != nil {
+		return nil, err
+	}
+	port, err := strconv.Atoi(portStr)
+	if err != nil {
+		return nil, err
+	}
+	return &net.TCPAddr{
+		IP:   net.ParseIP(ipStr),
+		Port: port,
+	}, nil
+}
+
+func newLocalnode(priv *ecdsa.PrivateKey, ipAddr *net.TCPAddr, udpPort int, wakuFlags utils.WakuEnrBitfield, advertiseAddr *net.IP, log *zap.Logger) (*enode.LocalNode, error) {
+	db, err := enode.OpenDB("")
+	if err != nil {
+		return nil, err
+	}
+	localnode := enode.NewLocalNode(db, priv)
+	localnode.SetFallbackUDP(udpPort)
+	localnode.Set(enr.WithEntry(utils.WakuENRField, wakuFlags))
+	localnode.SetFallbackIP(net.IP{127, 0, 0, 1})
+	localnode.SetStaticIP(ipAddr.IP)
+
+	if udpPort > 0 && udpPort <= math.MaxUint16 {
+		localnode.Set(enr.UDP(uint16(udpPort))) // lgtm [go/incorrect-integer-conversion]
+	} else {
+		log.Error("setting udpPort", zap.Int("port", udpPort))
+	}
+
+	if ipAddr.Port > 0 && ipAddr.Port <= math.MaxUint16 {
+		localnode.Set(enr.TCP(uint16(ipAddr.Port))) // lgtm [go/incorrect-integer-conversion]
+	} else {
+		log.Error("setting tcpPort", zap.Int("port", ipAddr.Port))
+	}
+
+	if advertiseAddr != nil {
+		localnode.SetStaticIP(*advertiseAddr)
+	}
+
+	return localnode, nil
+}
+
+func TestRetrieveProvidePeerExchangePeers(t *testing.T) {
+	// H1
+	host1, _, prvKey1 := createHost(t)
+	udpPort1, err := tests.FindFreePort(t, "127.0.0.1", 3)
+	require.NoError(t, err)
+	ip1, _ := extractIP(host1.Addrs()[0])
+	l1, err := newLocalnode(prvKey1, ip1, udpPort1, utils.NewWakuEnrBitfield(false, false, false, true), nil, utils.Logger())
+	require.NoError(t, err)
+	d1, err := discv5.NewDiscoveryV5(host1, prvKey1, l1, utils.Logger(), discv5.WithUDPPort(udpPort1))
+	require.NoError(t, err)
+
+	// H2
+	host2, _, prvKey2 := createHost(t)
+	ip2, _ := extractIP(host2.Addrs()[0])
+	udpPort2, err := tests.FindFreePort(t, "127.0.0.1", 3)
+	require.NoError(t, err)
+	l2, err := newLocalnode(prvKey2, ip2, udpPort2, utils.NewWakuEnrBitfield(false, false, false, true), nil, utils.Logger())
+	require.NoError(t, err)
+	d2, err := discv5.NewDiscoveryV5(host2, prvKey2, l2, utils.Logger(), discv5.WithUDPPort(udpPort2), discv5.WithBootnodes([]*enode.Node{d1.Node()}))
+	require.NoError(t, err)
+
+	// H3
+	host3, _, _ := createHost(t)
+
+	defer d1.Stop()
+	defer d2.Stop()
+	defer host1.Close()
+	defer host2.Close()
+	defer host3.Close()
+
+	err = d1.Start()
+	require.NoError(t, err)
+
+	err = d2.Start()
+	require.NoError(t, err)
+
+	// mount peer exchange
+	px1 := NewWakuPeerExchange(context.Background(), host1, d1, utils.Logger())
+	px3 := NewWakuPeerExchange(context.Background(), host3, nil, utils.Logger())
+
+	err = px1.Start()
+	require.NoError(t, err)
+
+	err = px3.Start()
+	require.NoError(t, err)
+
+	time.Sleep(3 * time.Second) // Give the algorithm some time to work its magic
+
+	host3.Peerstore().AddAddrs(host1.ID(), host1.Addrs(), peerstore.PermanentAddrTTL)
+	err = host3.Peerstore().AddProtocols(host1.ID(), string(PeerExchangeID_v20alpha1))
+	require.NoError(t, err)
+
+	err = px3.Request(context.Background(), 1)
+	require.NoError(t, err)
+
+	time.Sleep(3 * time.Second) //  Give the algorithm some time to work its magic
+
+	peer2Info := host3.Peerstore().PeerInfo(host2.ID())
+	require.Equal(t, host2.Addrs()[0], peer2Info.Addrs[0])
+
+	px1.Stop()
+	px3.Stop()
+}