obey the multiaddr's IP version when dialing

.travis.yml

@@ -18,6 +18,10 @@ before_install:
   - export GOARCH=$TRAVIS_GOARCH
   - go env # for debugging
 
+# see https://github.com/travis-ci/travis-ci/issues/8361#issuecomment-350090030
+before_script:
+  - sudo sh -c 'echo 0 > /proc/sys/net/ipv6/conf/all/disable_ipv6'
+
 script:
   - ginkgo -r --cover --randomizeAllSpecs --randomizeSuites --trace --progress
 

conn_test.go

@@ -35,12 +35,12 @@ var _ = Describe("Connection", func() {
 		return id, priv
 	}
 
-	runServer := func(tr tpt.Transport) (ma.Multiaddr, <-chan tpt.Conn) {
+	runServer := func(tr tpt.Transport, multiaddr string) (ma.Multiaddr, <-chan tpt.Conn) {
 		addrChan := make(chan ma.Multiaddr)
 		connChan := make(chan tpt.Conn)
 		go func() {
 			defer GinkgoRecover()
-			addr, err := ma.NewMultiaddr("/ip4/127.0.0.1/udp/0/quic")
+			addr, err := ma.NewMultiaddr(multiaddr)
 			Expect(err).ToNot(HaveOccurred())
 			ln, err := tr.Listen(addr)
 			Expect(err).ToNot(HaveOccurred())
@@ -62,10 +62,30 @@ var _ = Describe("Connection", func() {
 		clientID, clientKey = createPeer()
 	})
 
-	It("handshakes", func() {
+	It("handshakes on IPv4", func() {
 		serverTransport, err := NewTransport(serverKey)
 		Expect(err).ToNot(HaveOccurred())
-		serverAddr, serverConnChan := runServer(serverTransport)
+		serverAddr, serverConnChan := runServer(serverTransport, "/ip4/127.0.0.1/udp/0/quic")
+
+		clientTransport, err := NewTransport(clientKey)
+		Expect(err).ToNot(HaveOccurred())
+		conn, err := clientTransport.Dial(context.Background(), serverAddr, serverID)
+		Expect(err).ToNot(HaveOccurred())
+		serverConn := <-serverConnChan
+		Expect(conn.LocalPeer()).To(Equal(clientID))
+		Expect(conn.LocalPrivateKey()).To(Equal(clientKey))
+		Expect(conn.RemotePeer()).To(Equal(serverID))
+		Expect(conn.RemotePublicKey()).To(Equal(serverKey.GetPublic()))
+		Expect(serverConn.LocalPeer()).To(Equal(serverID))
+		Expect(serverConn.LocalPrivateKey()).To(Equal(serverKey))
+		Expect(serverConn.RemotePeer()).To(Equal(clientID))
+		Expect(serverConn.RemotePublicKey()).To(Equal(clientKey.GetPublic()))
+	})
+
+	It("handshakes on IPv6", func() {
+		serverTransport, err := NewTransport(serverKey)
+		Expect(err).ToNot(HaveOccurred())
+		serverAddr, serverConnChan := runServer(serverTransport, "/ip6/::1/udp/0/quic")
 
 		clientTransport, err := NewTransport(clientKey)
 		Expect(err).ToNot(HaveOccurred())
@@ -85,7 +105,7 @@ var _ = Describe("Connection", func() {
 	It("opens and accepts streams", func() {
 		serverTransport, err := NewTransport(serverKey)
 		Expect(err).ToNot(HaveOccurred())
-		serverAddr, serverConnChan := runServer(serverTransport)
+		serverAddr, serverConnChan := runServer(serverTransport, "/ip4/127.0.0.1/udp/0/quic")
 
 		clientTransport, err := NewTransport(clientKey)
 		Expect(err).ToNot(HaveOccurred())
@@ -110,7 +130,7 @@ var _ = Describe("Connection", func() {
 
 		serverTransport, err := NewTransport(serverKey)
 		Expect(err).ToNot(HaveOccurred())
-		serverAddr, serverConnChan := runServer(serverTransport)
+		serverAddr, serverConnChan := runServer(serverTransport, "/ip4/127.0.0.1/udp/0/quic")
 
 		clientTransport, err := NewTransport(clientKey)
 		Expect(err).ToNot(HaveOccurred())
@@ -124,7 +144,7 @@ var _ = Describe("Connection", func() {
 	It("fails if the client presents an invalid cert chain", func() {
 		serverTransport, err := NewTransport(serverKey)
 		Expect(err).ToNot(HaveOccurred())
-		serverAddr, serverConnChan := runServer(serverTransport)
+		serverAddr, serverConnChan := runServer(serverTransport, "/ip4/127.0.0.1/udp/0/quic")
 
 		clientTransport, err := NewTransport(clientKey)
 		invalidateCertChain(clientTransport.(*transport).tlsConf)
@@ -139,7 +159,7 @@ var _ = Describe("Connection", func() {
 		serverTransport, err := NewTransport(serverKey)
 		invalidateCertChain(serverTransport.(*transport).tlsConf)
 		Expect(err).ToNot(HaveOccurred())
-		serverAddr, serverConnChan := runServer(serverTransport)
+		serverAddr, serverConnChan := runServer(serverTransport, "/ip4/127.0.0.1/udp/0/quic")
 
 		clientTransport, err := NewTransport(clientKey)
 		Expect(err).ToNot(HaveOccurred())
@@ -152,7 +172,7 @@ var _ = Describe("Connection", func() {
 	It("keeps accepting connections after a failed connection attempt", func() {
 		serverTransport, err := NewTransport(serverKey)
 		Expect(err).ToNot(HaveOccurred())
-		serverAddr, serverConnChan := runServer(serverTransport)
+		serverAddr, serverConnChan := runServer(serverTransport, "/ip4/127.0.0.1/udp/0/quic")
 
 		// first dial with an invalid cert chain
 		clientTransport1, err := NewTransport(clientKey)
@@ -175,10 +195,10 @@ var _ = Describe("Connection", func() {
 
 		serverTransport, err := NewTransport(serverKey)
 		Expect(err).ToNot(HaveOccurred())
-		serverAddr, serverConnChan := runServer(serverTransport)
+		serverAddr, serverConnChan := runServer(serverTransport, "/ip4/127.0.0.1/udp/0/quic")
 		serverTransport2, err := NewTransport(serverKey2)
 		Expect(err).ToNot(HaveOccurred())
-		serverAddr2, serverConnChan2 := runServer(serverTransport2)
+		serverAddr2, serverConnChan2 := runServer(serverTransport2, "/ip4/127.0.0.1/udp/0/quic")
 
 		data := bytes.Repeat([]byte{'a'}, 5*1<<20) // 5 MB
 		// wait for both servers to accept a connection

transport.go

@@ -5,7 +5,9 @@ import (
 	"crypto/tls"
 	"crypto/x509"
 	"errors"
+	"fmt"
 	"net"
+	"sync"
 
 	ic "github.com/libp2p/go-libp2p-crypto"
 	peer "github.com/libp2p/go-libp2p-peer"
@@ -27,12 +29,47 @@ var quicConfig = &quic.Config{
 	KeepAlive: true,
 }
 
+type connManager struct {
+	connIPv4Once sync.Once
+	connIPv4     net.PacketConn
+
+	connIPv6Once sync.Once
+	connIPv6     net.PacketConn
+}
+
+func (c *connManager) GetConnForAddr(network string) (net.PacketConn, error) {
+	switch network {
+	case "udp4":
+		var err error
+		c.connIPv4Once.Do(func() {
+			c.connIPv4, err = c.createConn(network, "0.0.0.0:0")
+		})
+		return c.connIPv4, err
+	case "udp6":
+		var err error
+		c.connIPv6Once.Do(func() {
+			c.connIPv6, err = c.createConn(network, ":0")
+		})
+		return c.connIPv6, err
+	default:
+		return nil, fmt.Errorf("unsupported network: %s", network)
+	}
+}
+
+func (c *connManager) createConn(network, host string) (net.PacketConn, error) {
+	addr, err := net.ResolveUDPAddr(network, host)
+	if err != nil {
+		return nil, err
+	}
+	return net.ListenUDP(network, addr)
+}
+
 // The Transport implements the tpt.Transport interface for QUIC connections.
 type transport struct {
 	privKey     ic.PrivKey
 	localPeer   peer.ID
 	tlsConf     *tls.Config
-	pconn     net.PacketConn
+	connManager *connManager
 }
 
 var _ tpt.Transport = &transport{}
@@ -48,27 +85,21 @@ func NewTransport(key ic.PrivKey) (tpt.Transport, error) {
 		return nil, err
 	}
 
-	// create a packet conn for outgoing connections
-	addr, err := net.ResolveUDPAddr("udp", "localhost:0")
-	if err != nil {
-		return nil, err
-	}
-	conn, err := net.ListenUDP("udp", addr)
-	if err != nil {
-		return nil, err
-	}
-
 	return &transport{
 		privKey:     key,
 		localPeer:   localPeer,
 		tlsConf:     tlsConf,
-		pconn:     conn,
+		connManager: &connManager{},
 	}, nil
 }
 
 // Dial dials a new QUIC connection
 func (t *transport) Dial(ctx context.Context, raddr ma.Multiaddr, p peer.ID) (tpt.Conn, error) {
-	_, host, err := manet.DialArgs(raddr)
+	network, host, err := manet.DialArgs(raddr)
+	if err != nil {
+		return nil, err
+	}
+	pconn, err := t.connManager.GetConnForAddr(network)
 	if err != nil {
 		return nil, err
 	}
@@ -100,7 +131,7 @@ func (t *transport) Dial(ctx context.Context, raddr ma.Multiaddr, p peer.ID) (tp
 		}
 		return nil
 	}
-	sess, err := quic.DialContext(ctx, t.pconn, addr, host, tlsConf, quicConfig)
+	sess, err := quic.DialContext(ctx, pconn, addr, host, tlsConf, quicConfig)
 	if err != nil {
 		return nil, err
 	}