add hole punching support (#194)

p2p/transport/quic/conn_test.go

@@ -11,14 +11,14 @@ import (
 	"sync/atomic"
 	"time"
 
-	gomock "github.com/golang/mock/gomock"
 	ic "github.com/libp2p/go-libp2p-core/crypto"
+	n "github.com/libp2p/go-libp2p-core/network"
 	"github.com/libp2p/go-libp2p-core/peer"
 	tpt "github.com/libp2p/go-libp2p-core/transport"
-
 	quicproxy "github.com/lucas-clemente/quic-go/integrationtests/tools/proxy"
 	ma "github.com/multiformats/go-multiaddr"
 
+	"github.com/golang/mock/gomock"
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
 )
@@ -345,4 +345,53 @@ var _ = Describe("Connection", func() {
 		Expect(rerr).To(HaveOccurred())
 		Expect(rerr.Error()).To(ContainSubstring("received a stateless reset"))
 	})
+
+	It("hole punches", func() {
+		t1, err := NewTransport(serverKey, nil, nil)
+		Expect(err).ToNot(HaveOccurred())
+		laddr, err := ma.NewMultiaddr("/ip4/127.0.0.1/udp/0/quic")
+		Expect(err).ToNot(HaveOccurred())
+		ln1, err := t1.Listen(laddr)
+		Expect(err).ToNot(HaveOccurred())
+		done1 := make(chan struct{})
+		go func() {
+			defer GinkgoRecover()
+			defer close(done1)
+			if _, err := ln1.Accept(); err == nil {
+				Fail("didn't expect to accept any connections")
+			}
+		}()
+
+		t2, err := NewTransport(clientKey, nil, nil)
+		Expect(err).ToNot(HaveOccurred())
+		ln2, err := t2.Listen(laddr)
+		Expect(err).ToNot(HaveOccurred())
+		done2 := make(chan struct{})
+		go func() {
+			defer GinkgoRecover()
+			defer close(done2)
+			if _, err := ln2.Accept(); err == nil {
+				Fail("didn't expect to accept any connections")
+			}
+		}()
+		connChan := make(chan tpt.CapableConn)
+		go func() {
+			defer GinkgoRecover()
+			conn, err := t2.Dial(n.WithSimultaneousConnect(context.Background(), ""), ln1.Multiaddr(), serverID)
+			Expect(err).ToNot(HaveOccurred())
+			connChan <- conn
+		}()
+		conn1, err := t1.Dial(n.WithSimultaneousConnect(context.Background(), ""), ln2.Multiaddr(), clientID)
+		Expect(err).ToNot(HaveOccurred())
+		defer conn1.Close()
+		Expect(conn1.RemotePeer()).To(Equal(clientID))
+		var conn2 tpt.CapableConn
+		Eventually(connChan).Should(Receive(&conn2))
+		defer conn2.Close()
+		Expect(conn2.RemotePeer()).To(Equal(serverID))
+		ln1.Close()
+		ln2.Close()
+		Eventually(done1).Should(BeClosed())
+		Eventually(done2).Should(BeClosed())
+	})
 })

p2p/transport/quic/listener.go

@@ -12,7 +12,7 @@ import (
 
 	p2ptls "github.com/libp2p/go-libp2p-tls"
 
-	quic "github.com/lucas-clemente/quic-go"
+	"github.com/lucas-clemente/quic-go"
 	ma "github.com/multiformats/go-multiaddr"
 )
 
@@ -74,6 +74,21 @@ func (l *listener) Accept() (tpt.CapableConn, error) {
 			sess.CloseWithError(errorCodeConnectionGating, "connection gated")
 			continue
 		}
+
+		// return through active hole punching if any
+		key := holePunchKey{addr: sess.RemoteAddr().String(), peer: conn.remotePeerID}
+		var wasHolePunch bool
+		l.transport.holePunchingMx.Lock()
+		holePunch, ok := l.transport.holePunching[key]
+		if ok && !holePunch.fulfilled {
+			holePunch.connCh <- conn
+			wasHolePunch = true
+			holePunch.fulfilled = true
+		}
+		l.transport.holePunchingMx.Unlock()
+		if wasHolePunch {
+			continue
+		}
 		return conn, nil
 	}
 }
@@ -92,6 +107,7 @@ func (l *listener) setupConn(sess quic.Session) (*conn, error) {
 	if err != nil {
 		return nil, err
 	}
+
 	remoteMultiaddr, err := toQuicMultiaddr(sess.RemoteAddr())
 	if err != nil {
 		return nil, err

p2p/transport/quic/transport.go

@@ -1,20 +1,23 @@
 package libp2pquic
 
 import (
+	"bytes"
 	"context"
 	"errors"
 	"fmt"
 	"io"
+	"math/rand"
 	"net"
-
-	"github.com/libp2p/go-libp2p-core/connmgr"
-	n "github.com/libp2p/go-libp2p-core/network"
+	"sync"
+	"time"
 
 	"github.com/minio/sha256-simd"
 	"golang.org/x/crypto/hkdf"
 
 	logging "github.com/ipfs/go-log"
+	"github.com/libp2p/go-libp2p-core/connmgr"
 	ic "github.com/libp2p/go-libp2p-core/crypto"
+	n "github.com/libp2p/go-libp2p-core/network"
 	"github.com/libp2p/go-libp2p-core/peer"
 	"github.com/libp2p/go-libp2p-core/pnet"
 	tpt "github.com/libp2p/go-libp2p-core/transport"
@@ -27,8 +30,12 @@ import (
 
 var log = logging.Logger("quic-transport")
 
+var ErrHolePunching = errors.New("hole punching attempted; no active dial")
+
 var quicDialContext = quic.DialContext // so we can mock it in tests
 
+var HolePunchTimeout = 5 * time.Second
+
 var quicConfig = &quic.Config{
 	MaxIncomingStreams:         1000,
 	MaxIncomingUniStreams:      -1,             // disable unidirectional streams
@@ -96,10 +103,23 @@ type transport struct {
 	serverConfig *quic.Config
 	clientConfig *quic.Config
 	gater        connmgr.ConnectionGater
+
+	holePunchingMx sync.Mutex
+	holePunching   map[holePunchKey]*activeHolePunch
 }
 
 var _ tpt.Transport = &transport{}
 
+type holePunchKey struct {
+	addr string
+	peer peer.ID
+}
+
+type activeHolePunch struct {
+	connCh    chan tpt.CapableConn
+	fulfilled bool
+}
+
 // NewTransport creates a new QUIC transport
 func NewTransport(key ic.PrivKey, psk pnet.PSK, gater connmgr.ConnectionGater) (tpt.Transport, error) {
 	if len(psk) > 0 {
@@ -138,6 +158,7 @@ func NewTransport(key ic.PrivKey, psk pnet.PSK, gater connmgr.ConnectionGater) (
 		serverConfig: config,
 		clientConfig: config.Clone(),
 		gater:        gater,
+		holePunching: make(map[holePunchKey]*activeHolePunch),
 	}, nil
 }
 
@@ -156,6 +177,13 @@ func (t *transport) Dial(ctx context.Context, raddr ma.Multiaddr, p peer.ID) (tp
 		return nil, err
 	}
 	tlsConf, keyCh := t.identity.ConfigForPeer(p)
+
+	if simConnect, _ := n.GetSimultaneousConnect(ctx); simConnect {
+		if bytes.Compare([]byte(t.localPeer), []byte(p)) < 0 {
+			return t.holePunch(ctx, network, addr, p)
+		}
+	}
+
 	pconn, err := t.connManager.Dial(network, addr)
 	if err != nil {
 		return nil, err
@@ -202,6 +230,82 @@ func (t *transport) Dial(ctx context.Context, raddr ma.Multiaddr, p peer.ID) (tp
 	return conn, nil
 }
 
+func (t *transport) holePunch(ctx context.Context, network string, addr *net.UDPAddr, p peer.ID) (tpt.CapableConn, error) {
+	pconn, err := t.connManager.Dial(network, addr)
+	if err != nil {
+		return nil, err
+	}
+	defer pconn.DecreaseCount()
+
+	ctx, cancel := context.WithTimeout(ctx, HolePunchTimeout)
+	defer cancel()
+
+	key := holePunchKey{addr: addr.String(), peer: p}
+	t.holePunchingMx.Lock()
+	if _, ok := t.holePunching[key]; ok {
+		t.holePunchingMx.Unlock()
+		return nil, fmt.Errorf("already punching hole for %s", addr)
+	}
+	connCh := make(chan tpt.CapableConn, 1)
+	t.holePunching[key] = &activeHolePunch{connCh: connCh}
+	t.holePunchingMx.Unlock()
+
+	var timer *time.Timer
+	defer func() {
+		if timer != nil {
+			timer.Stop()
+		}
+	}()
+
+	payload := make([]byte, 64)
+	var punchErr error
+loop:
+	for i := 0; ; i++ {
+		if _, err := rand.Read(payload); err != nil {
+			punchErr = err
+			break
+		}
+		if _, err := pconn.UDPConn.WriteToUDP(payload, addr); err != nil {
+			punchErr = err
+			break
+		}
+
+		maxSleep := 10 * (i + 1) * (i + 1) // in ms
+		if maxSleep > 200 {
+			maxSleep = 200
+		}
+		d := 10*time.Millisecond + time.Duration(rand.Intn(maxSleep))*time.Millisecond
+		if timer == nil {
+			timer = time.NewTimer(d)
+		} else {
+			timer.Reset(d)
+		}
+		select {
+		case c := <-connCh:
+			t.holePunchingMx.Lock()
+			delete(t.holePunching, key)
+			t.holePunchingMx.Unlock()
+			return c, nil
+		case <-timer.C:
+		case <-ctx.Done():
+			punchErr = ErrHolePunching
+			break loop
+		}
+	}
+	// we only arrive here if punchErr != nil
+	t.holePunchingMx.Lock()
+	defer func() {
+		delete(t.holePunching, key)
+		t.holePunchingMx.Unlock()
+	}()
+	select {
+	case c := <-t.holePunching[key].connCh:
+		return c, nil
+	default:
+		return nil, punchErr
+	}
+}
+
 // Don't use mafmt.QUIC as we don't want to dial DNS addresses. Just /ip{4,6}/udp/quic
 var dialMatcher = mafmt.And(mafmt.IP, mafmt.Base(ma.P_UDP), mafmt.Base(ma.P_QUIC))
 

p2p/transport/quic/transport_test.go

@@ -11,7 +11,7 @@ import (
 
 	ic "github.com/libp2p/go-libp2p-core/crypto"
 	tpt "github.com/libp2p/go-libp2p-core/transport"
-	quic "github.com/lucas-clemente/quic-go"
+	"github.com/lucas-clemente/quic-go"
 	ma "github.com/multiformats/go-multiaddr"
 
 	. "github.com/onsi/ginkgo"