Adds RPC inspector (#8)

* perf: use msgio pooled buffers for received msgs (libp2p#500)

* perf: use pooled buffers for message writes (libp2p#507)

* improve handling of dead peers (libp2p#508)

* chore: ignore signing keys during WithLocalPublication publishing (libp2p#497)

* adds app specific rpc handler

Co-authored-by: Hlib Kanunnikov <hlibwondertan@gmail.com>
Co-authored-by: Viacheslav <viacheslavgonkivskyi@gmail.com>

comm.go

@@ -1,19 +1,20 @@
 package pubsub
 
 import (
-	"bufio"
 	"context"
+	"encoding/binary"
 	"io"
 	"time"
 
+	"github.com/gogo/protobuf/proto"
+	pool "github.com/libp2p/go-buffer-pool"
+	"github.com/multiformats/go-varint"
+
 	"github.com/libp2p/go-libp2p/core/network"
 	"github.com/libp2p/go-libp2p/core/peer"
+	"github.com/libp2p/go-msgio"
 
 	pb "github.com/libp2p/go-libp2p-pubsub/pb"
-
-	"github.com/libp2p/go-msgio/protoio"
-
-	"github.com/gogo/protobuf/proto"
 )
 
 // get the initial RPC containing all of our subscriptions to send to new peers
@@ -60,11 +61,11 @@ func (p *PubSub) handleNewStream(s network.Stream) {
 		p.inboundStreamsMx.Unlock()
 	}()
 
-	r := protoio.NewDelimitedReader(s, p.maxMessageSize)
+	r := msgio.NewVarintReaderSize(s, p.maxMessageSize)
 	for {
-		rpc := new(RPC)
-		err := r.ReadMsg(&rpc.RPC)
+		msgbytes, err := r.ReadMsg()
 		if err != nil {
+			r.ReleaseMsg(msgbytes)
 			if err != io.EOF {
 				s.Reset()
 				log.Debugf("error reading rpc from %s: %s", s.Conn().RemotePeer(), err)
@@ -77,6 +78,15 @@ func (p *PubSub) handleNewStream(s network.Stream) {
 			return
 		}
 
+		rpc := new(RPC)
+		err = rpc.Unmarshal(msgbytes)
+		r.ReleaseMsg(msgbytes)
+		if err != nil {
+			s.Reset()
+			log.Warnf("bogus rpc from %s: %s", s.Conn().RemotePeer(), err)
+			return
+		}
+
 		rpc.from = peer
 		select {
 		case p.incoming <- rpc:
@@ -115,7 +125,7 @@ func (p *PubSub) handleNewPeer(ctx context.Context, pid peer.ID, outgoing <-chan
 	}
 
 	go p.handleSendingMessages(ctx, s, outgoing)
-	go p.handlePeerEOF(ctx, s)
+	go p.handlePeerDead(s)
 	select {
 	case p.newPeerStream <- s:
 	case <-ctx.Done():
@@ -131,32 +141,33 @@ func (p *PubSub) handleNewPeerWithBackoff(ctx context.Context, pid peer.ID, back
 	}
 }
 
-func (p *PubSub) handlePeerEOF(ctx context.Context, s network.Stream) {
+func (p *PubSub) handlePeerDead(s network.Stream) {
 	pid := s.Conn().RemotePeer()
-	r := protoio.NewDelimitedReader(s, p.maxMessageSize)
-	rpc := new(RPC)
-	for {
-		err := r.ReadMsg(&rpc.RPC)
-		if err != nil {
-			p.notifyPeerDead(pid)
-			return
-		}
 
+	_, err := s.Read([]byte{0})
+	if err == nil {
 		log.Debugf("unexpected message from %s", pid)
 	}
+
+	s.Reset()
+	p.notifyPeerDead(pid)
 }
 
 func (p *PubSub) handleSendingMessages(ctx context.Context, s network.Stream, outgoing <-chan *RPC) {
-	bufw := bufio.NewWriter(s)
-	wc := protoio.NewDelimitedWriter(bufw)
+	writeRpc := func(rpc *RPC) error {
+		size := uint64(rpc.Size())
+
+		buf := pool.Get(varint.UvarintSize(size) + int(size))
+		defer pool.Put(buf)
 
-	writeMsg := func(msg proto.Message) error {
-		err := wc.WriteMsg(msg)
+		n := binary.PutUvarint(buf, size)
+		_, err := rpc.MarshalTo(buf[n:])
 		if err != nil {
 			return err
 		}
 
-		return bufw.Flush()
+		_, err = s.Write(buf)
+		return err
 	}
 
 	defer s.Close()
@@ -167,7 +178,7 @@ func (p *PubSub) handleSendingMessages(ctx context.Context, s network.Stream, ou
 				return
 			}
 
-			err := writeMsg(&rpc.RPC)
+			err := writeRpc(rpc)
 			if err != nil {
 				s.Reset()
 				log.Debugf("writing message to %s: %s", s.Conn().RemotePeer(), err)

gossipsub.go

@@ -217,9 +217,9 @@ func NewGossipSubWithRouter(ctx context.Context, h host.Host, rt PubSubRouter, o
 }
 
 // DefaultGossipSubRouter returns a new GossipSubRouter with default parameters.
-func DefaultGossipSubRouter(h host.Host) *GossipSubRouter {
+func DefaultGossipSubRouter(h host.Host, opts ...func(*GossipSubRouter)) *GossipSubRouter {
 	params := DefaultGossipSubParams()
-	return &GossipSubRouter{
+	rt := &GossipSubRouter{
 		peers:     make(map[peer.ID]protocol.ID),
 		mesh:      make(map[string]map[peer.ID]struct{}),
 		fanout:    make(map[string]map[peer.ID]struct{}),
@@ -237,6 +237,18 @@ func DefaultGossipSubRouter(h host.Host) *GossipSubRouter {
 		tagTracer: newTagTracer(h.ConnManager()),
 		params:    params,
 	}
+
+	for _, opt := range opts {
+		opt(rt)
+	}
+
+	return rt
+}
+
+func WithAppSpecificRpcInspector(inspector func(peer.ID, *RPC) bool) func(*GossipSubRouter) {
+	return func(rt *GossipSubRouter) {
+		rt.appSpecificRpcInspector = inspector
+	}
 }
 
 // DefaultGossipSubParams returns the default gossip sub parameters
@@ -474,6 +486,11 @@ type GossipSubRouter struct {
 	// number of heartbeats since the beginning of time; this allows us to amortize some resource
 	// clean up -- eg backoff clean up.
 	heartbeatTicks uint64
+
+	// appSpecificRpcInspector is an auxiliary that may be set by the application to inspect incoming RPCs prior to
+	// processing them. The inspector is invoked on an accepted RPC right prior to handling it.
+	// The return value of the inspector function is a boolean indicating whether the RPC should be processed or not.
+	appSpecificRpcInspector func(peer.ID, *RPC) bool
 }
 
 type connectInfo struct {
@@ -614,6 +631,13 @@ func (gs *GossipSubRouter) HandleRPC(rpc *RPC) {
 		return
 	}
 
+	if gs.appSpecificRpcInspector != nil {
+		// check if the RPC is allowed by the external inspector
+		if accept := gs.appSpecificRpcInspector(rpc.from, rpc); !accept {
+			return // reject the RPC
+		}
+	}
+
 	iwant := gs.handleIHave(rpc.from, ctl)
 	ihave := gs.handleIWant(rpc.from, ctl)
 	prune := gs.handleGraft(rpc.from, ctl)

topic.go

@@ -239,7 +239,7 @@ func (t *Topic) Publish(ctx context.Context, data []byte, opts ...PubOpt) error
 		}
 	}
 
-	if pub.customKey != nil {
+	if pub.customKey != nil && !pub.local {
 		key, pid = pub.customKey()
 		if key == nil {
 			return ErrNilSignKey