swarm: add mock net.PacketConn for testing

This uses https://github.com/tailscale/tailscale/tree/main/tstest/natlab
to provide a mock net.PacketConn. This allows us to fake quic addresses
on nodes to test for address discovery. This can also be used to test
nat traversal.

go.mod

@@ -59,6 +59,7 @@ require (
 	golang.org/x/sys v0.10.0
 	golang.org/x/tools v0.11.0
 	google.golang.org/protobuf v1.30.0
+	tailscale.com v1.40.1
 )
 
 require (
@@ -75,7 +76,6 @@ require (
 	github.com/dustin/go-humanize v1.0.0 // indirect
 	github.com/elastic/gosigar v0.14.2 // indirect
 	github.com/francoispqt/gojay v1.2.13 // indirect
-	github.com/fsnotify/fsnotify v1.5.4 // indirect
 	github.com/go-task/slim-sprig v0.0.0-20230315185526-52ccab3ef572 // indirect
 	github.com/godbus/dbus/v5 v5.1.0 // indirect
 	github.com/gogo/protobuf v1.3.2 // indirect
@@ -99,8 +99,8 @@ require (
 	github.com/opencontainers/runtime-spec v1.0.2 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
-	github.com/prometheus/common v0.37.0 // indirect
-	github.com/prometheus/procfs v0.8.0 // indirect
+	github.com/prometheus/common v0.41.0 // indirect
+	github.com/prometheus/procfs v0.9.0 // indirect
 	github.com/quic-go/qpack v0.4.0 // indirect
 	github.com/quic-go/qtls-go1-19 v0.3.2 // indirect
 	github.com/quic-go/qtls-go1-20 v0.2.2 // indirect

p2p/host/basic/basic_host_test.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"io"
+	"net/netip"
 	"reflect"
 	"sort"
 	"strings"
@@ -22,6 +23,7 @@ import (
 	"github.com/libp2p/go-libp2p/p2p/host/eventbus"
 	swarmt "github.com/libp2p/go-libp2p/p2p/net/swarm/testing"
 	"github.com/libp2p/go-libp2p/p2p/protocol/identify"
+	"tailscale.com/tstest/natlab"
 
 	ma "github.com/multiformats/go-multiaddr"
 
@@ -892,5 +894,50 @@ func TestInferWebtransportAddrsFromQuic(t *testing.T) {
 		})
 
 	}
+}
+
+func TestAddressDiscovery(t *testing.T) {
+	inet := &natlab.Network{Name: "internet", Prefix4: netip.MustParsePrefix("1.2.3.0/24")}
+	type TestHost struct {
+		H    *BasicHost
+		Addr ma.Multiaddr
+	}
+	port := 1000
+	newHost := func(name string) TestHost {
+		m := &natlab.Machine{Name: name}
+		mif := m.Attach("eth0", inet)
+		port++
+		listenAddr := ma.StringCast(fmt.Sprintf("/ip4/0.0.0.0/udp/%d/quic-v1", port))
+		publicAddr := ma.StringCast(fmt.Sprintf("/ip4/%s/udp/%d/quic-v1", mif.V4().String(), port))
+		h, err := NewHost(swarmt.GenSwarm(t, swarmt.OptQUICListenAddress(listenAddr), swarmt.OptUDPTransport(swarmt.UDPTransport(m))), nil)
+		if err != nil {
+			t.Fatal(err)
+		}
+		return TestHost{H: h, Addr: publicAddr}
+	}
+
+	var peers []TestHost
+	for i := 0; i < identify.ActivationThresh; i++ {
+		h := newHost(fmt.Sprintf("peer-%d", i))
+		h.H.IDService().Start()
+		peers = append(peers, h)
+	}
 
+	h := newHost("host")
+	h.H.IDService().Start()
+	for _, p := range peers {
+		ctx := network.WithDialPeerTimeout(context.Background(), 1*time.Second)
+		h.H.Peerstore().AddAddr(p.H.ID(), p.Addr, peerstore.TempAddrTTL)
+		err := h.H.Connect(ctx, peer.AddrInfo{ID: p.H.ID()})
+		if err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	require.Eventually(t,
+		func() bool {
+			return ma.Contains(h.H.Addrs(), h.Addr)
+		},
+		5*time.Second,
+		100*time.Millisecond)
 }

p2p/net/swarm/testing/testing.go

@@ -1,7 +1,9 @@
 package testing
 
 import (
+	"context"
 	"crypto/rand"
+	"net"
 	"testing"
 	"time"
 
@@ -24,6 +26,7 @@ import (
 	quic "github.com/libp2p/go-libp2p/p2p/transport/quic"
 	"github.com/libp2p/go-libp2p/p2p/transport/quicreuse"
 	"github.com/libp2p/go-libp2p/p2p/transport/tcp"
+	"tailscale.com/tstest/natlab"
 
 	ma "github.com/multiformats/go-multiaddr"
 	"github.com/stretchr/testify/require"
@@ -38,6 +41,8 @@ type config struct {
 	sk               crypto.PrivKey
 	swarmOpts        []swarm.Option
 	eventBus         event.Bus
+	quicListenAddr   ma.Multiaddr
+	udpTransport     quicreuse.UDPTransport
 	clock
 }
 
@@ -101,6 +106,18 @@ func OptPeerPrivateKey(sk crypto.PrivKey) Option {
 	}
 }
 
+func OptQUICListenAddress(addr ma.Multiaddr) Option {
+	return func(_ *testing.T, c *config) {
+		c.quicListenAddr = addr
+	}
+}
+
+func OptUDPTransport(tr quicreuse.UDPTransport) Option {
+	return func(_ *testing.T, c *config) {
+		c.udpTransport = tr
+	}
+}
+
 func EventBus(b event.Bus) Option {
 	return func(_ *testing.T, c *config) {
 		c.eventBus = b
@@ -175,7 +192,7 @@ func GenSwarm(t *testing.T, opts ...Option) *swarm.Swarm {
 		}
 	}
 	if !cfg.disableQUIC {
-		reuse, err := quicreuse.NewConnManager([32]byte{})
+		reuse, err := quicreuse.NewConnManager([32]byte{}, quicreuse.WithUDPTransport(cfg.udpTransport))
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -187,8 +204,14 @@ func GenSwarm(t *testing.T, opts ...Option) *swarm.Swarm {
 			t.Fatal(err)
 		}
 		if !cfg.dialOnly {
-			if err := s.Listen(ma.StringCast("/ip4/127.0.0.1/udp/0/quic")); err != nil {
-				t.Fatal(err)
+			if cfg.quicListenAddr == nil {
+				if err := s.Listen(ma.StringCast("/ip4/127.0.0.1/udp/0/quic")); err != nil {
+					t.Fatal(err)
+				}
+			} else {
+				if err := s.Listen(cfg.quicListenAddr); err != nil {
+					t.Fatal(err)
+				}
 			}
 		}
 	}
@@ -198,6 +221,22 @@ func GenSwarm(t *testing.T, opts ...Option) *swarm.Swarm {
 	return s
 }
 
+type udpTransport struct {
+	listenPacket func(network string, laddr *net.UDPAddr) (net.PacketConn, error)
+}
+
+func (u udpTransport) ListenPacket(network string, laddr *net.UDPAddr) (net.PacketConn, error) {
+	return u.listenPacket(network, laddr)
+}
+
+func UDPTransport(m *natlab.Machine) quicreuse.UDPTransport {
+	tr := udpTransport{}
+	tr.listenPacket = func(network string, laddr *net.UDPAddr) (net.PacketConn, error) {
+		return m.ListenPacket(context.Background(), network, laddr.String())
+	}
+	return tr
+}
+
 // DivulgeAddresses adds swarm a's addresses to swarm b's peerstore.
 func DivulgeAddresses(a, b network.Network) {
 	id := a.LocalPeer()

p2p/transport/quicreuse/connmgr.go

@@ -26,8 +26,9 @@ type ConnManager struct {
 	quicListenersMu sync.Mutex
 	quicListeners   map[string]quicListenerEntry
 
-	srk quic.StatelessResetKey
-	mt  *metricsTracer
+	srk          quic.StatelessResetKey
+	mt           *metricsTracer
+	udpTransport UDPTransport
 }
 
 type quicListenerEntry struct {
@@ -67,12 +68,15 @@ func NewConnManager(statelessResetKey quic.StatelessResetKey, opts ...Option) (*
 	if !cm.enableDraft29 {
 		serverConfig.Versions = []quic.VersionNumber{quic.Version1}
 	}
+	if cm.udpTransport == nil {
+		cm.udpTransport = defaultUDPTranport{}
+	}
 
 	cm.clientConfig = quicConf
 	cm.serverConfig = serverConfig
 	if cm.enableReuseport {
-		cm.reuseUDP4 = newReuse(&statelessResetKey, cm.mt)
-		cm.reuseUDP6 = newReuse(&statelessResetKey, cm.mt)
+		cm.reuseUDP4 = newReuse(&statelessResetKey, cm.mt, cm.udpTransport)
+		cm.reuseUDP6 = newReuse(&statelessResetKey, cm.mt, cm.udpTransport)
 	}
 	return cm, nil
 }
@@ -246,6 +250,16 @@ func (c *ConnManager) Close() error {
 	return c.reuseUDP4.Close()
 }
 
+type UDPTransport interface {
+	ListenPacket(network string, laddr *net.UDPAddr) (net.PacketConn, error)
+}
+
+type defaultUDPTranport struct{}
+
+func (defaultUDPTranport) ListenPacket(network string, laddr *net.UDPAddr) (net.PacketConn, error) {
+	return listenAndOptimize(network, laddr)
+}
+
 // listenAndOptimize same as net.ListenUDP, but also calls quic.OptimizeConn
 func listenAndOptimize(network string, laddr *net.UDPAddr) (net.PacketConn, error) {
 	conn, err := net.ListenUDP(network, laddr)

p2p/transport/quicreuse/options.go

@@ -26,3 +26,10 @@ func EnableMetrics() Option {
 		return nil
 	}
 }
+
+func WithUDPTransport(tr UDPTransport) Option {
+	return func(m *ConnManager) error {
+		m.udpTransport = tr
+		return nil
+	}
+}

p2p/transport/quicreuse/reuse.go

@@ -126,9 +126,10 @@ type reuse struct {
 
 	statelessResetKey *quic.StatelessResetKey
 	metricsTracer     *metricsTracer
+	udpTransport      UDPTransport
 }
 
-func newReuse(srk *quic.StatelessResetKey, mt *metricsTracer) *reuse {
+func newReuse(srk *quic.StatelessResetKey, mt *metricsTracer, tr UDPTransport) *reuse {
 	r := &reuse{
 		unicast:           make(map[string]map[int]*refcountedTransport),
 		globalListeners:   make(map[int]*refcountedTransport),
@@ -137,6 +138,7 @@ func newReuse(srk *quic.StatelessResetKey, mt *metricsTracer) *reuse {
 		gcStopChan:        make(chan struct{}),
 		statelessResetKey: srk,
 		metricsTracer:     mt,
+		udpTransport:      tr,
 	}
 	go r.gc()
 	return r
@@ -314,7 +316,7 @@ func (r *reuse) TransportForListen(network string, laddr *net.UDPAddr) (*refcoun
 		}
 	}
 
-	conn, err := listenAndOptimize(network, laddr)
+	conn, err := r.udpTransport.ListenPacket(network, laddr)
 	if err != nil {
 		return nil, err
 	}

p2p/transport/quicreuse/reuse_test.go

@@ -61,7 +61,7 @@ func cleanup(t *testing.T, reuse *reuse) {
 }
 
 func TestReuseListenOnAllIPv4(t *testing.T) {
-	reuse := newReuse(nil, nil)
+	reuse := newReuse(nil, nil, defaultUDPTranport{})
 	require.Eventually(t, isGarbageCollectorRunning, 500*time.Millisecond, 50*time.Millisecond, "expected garbage collector to be running")
 	cleanup(t, reuse)
 
@@ -73,7 +73,7 @@ func TestReuseListenOnAllIPv4(t *testing.T) {
 }
 
 func TestReuseListenOnAllIPv6(t *testing.T) {
-	reuse := newReuse(nil, nil)
+	reuse := newReuse(nil, nil, defaultUDPTranport{})
 	require.Eventually(t, isGarbageCollectorRunning, 500*time.Millisecond, 50*time.Millisecond, "expected garbage collector to be running")
 	cleanup(t, reuse)
 
@@ -86,7 +86,7 @@ func TestReuseListenOnAllIPv6(t *testing.T) {
 }
 
 func TestReuseCreateNewGlobalConnOnDial(t *testing.T) {
-	reuse := newReuse(nil, nil)
+	reuse := newReuse(nil, nil, defaultUDPTranport{})
 	cleanup(t, reuse)
 
 	addr, err := net.ResolveUDPAddr("udp4", "1.1.1.1:1234")
@@ -100,7 +100,7 @@ func TestReuseCreateNewGlobalConnOnDial(t *testing.T) {
 }
 
 func TestReuseConnectionWhenDialing(t *testing.T) {
-	reuse := newReuse(nil, nil)
+	reuse := newReuse(nil, nil, defaultUDPTranport{})
 	cleanup(t, reuse)
 
 	addr, err := net.ResolveUDPAddr("udp4", "0.0.0.0:0")
@@ -117,7 +117,7 @@ func TestReuseConnectionWhenDialing(t *testing.T) {
 }
 
 func TestReuseConnectionWhenListening(t *testing.T) {
-	reuse := newReuse(nil, nil)
+	reuse := newReuse(nil, nil, defaultUDPTranport{})
 	cleanup(t, reuse)
 
 	raddr, err := net.ResolveUDPAddr("udp4", "1.1.1.1:1234")
@@ -132,7 +132,7 @@ func TestReuseConnectionWhenListening(t *testing.T) {
 }
 
 func TestReuseConnectionWhenDialBeforeListen(t *testing.T) {
-	reuse := newReuse(nil, nil)
+	reuse := newReuse(nil, nil, defaultUDPTranport{})
 	cleanup(t, reuse)
 
 	// dial any address
@@ -166,7 +166,7 @@ func TestReuseListenOnSpecificInterface(t *testing.T) {
 	if platformHasRoutingTables() {
 		t.Skip("this test only works on platforms that support routing tables")
 	}
-	reuse := newReuse(nil, nil)
+	reuse := newReuse(nil, nil, defaultUDPTranport{})
 	cleanup(t, reuse)
 
 	router, err := netroute.New()
@@ -203,7 +203,7 @@ func TestReuseGarbageCollect(t *testing.T) {
 		maxUnusedDuration = 10 * maxUnusedDuration
 	}
 
-	reuse := newReuse(nil, nil)
+	reuse := newReuse(nil, nil, defaultUDPTranport{})
 	cleanup(t, reuse)
 
 	numGlobals := func() int {

test-plans/go.sum

@@ -54,7 +54,7 @@ github.com/flynn/noise v1.0.0/go.mod h1:xbMo+0i6+IGbYdJhF31t2eR1BIU0CYc12+BNAKwU
 github.com/francoispqt/gojay v1.2.13 h1:d2m3sFjloqoIUQU3TsHBgj6qg/BVGlTBeHDUmyJnXKk=
 github.com/francoispqt/gojay v1.2.13/go.mod h1:ehT5mTG4ua4581f1++1WLG0vPdaA9HaiDsoyrBGkyDY=
 github.com/fsnotify/fsnotify v1.4.7/go.mod h1:jwhsz4b93w/PPRr/qN1Yymfu8t87LnFCMoQvtojpjFo=
-github.com/fsnotify/fsnotify v1.5.4 h1:jRbGcIw6P2Meqdwuo0H1p6JVLbL5DHKAKlYndzMwVZI=
+github.com/fsnotify/fsnotify v1.4.9 h1:hsms1Qyu0jgnwNXIxa+/V/PDsU6CfLf6CNO8H7IWoS4=
 github.com/ghodss/yaml v1.0.0/go.mod h1:4dBDuWmgqj2HViK6kFavaiC9ZROes6MMH2rRYeMEF04=
 github.com/gliderlabs/ssh v0.1.1/go.mod h1:U7qILu1NlMHj9FlMhZLlkCdDnU1DBEAqr0aevW3Awn0=
 github.com/go-errors/errors v1.0.1/go.mod h1:f4zRHt4oKfwPJE5k8C9vpYG+aDHdBFUsgrm6/TyX73Q=
@@ -456,3 +456,4 @@ lukechampine.com/blake3 v1.2.1 h1:YuqqRuaqsGV71BV/nm9xlI0MKUv4QC54jQnBChWbGnI=
 lukechampine.com/blake3 v1.2.1/go.mod h1:0OFRp7fBtAylGVCO40o87sbupkyIGgbpv1+M1k1LM6k=
 sourcegraph.com/sourcegraph/go-diff v0.5.0/go.mod h1:kuch7UrkMzY0X+p9CRK03kfuPQ2zzQcaEFbx8wA8rck=
 sourcegraph.com/sqs/pbtypes v0.0.0-20180604144634-d3ebe8f20ae4/go.mod h1:ketZ/q3QxT9HOBeFhu6RdvsftgpsbFHBF5Cas6cDKZ0=
+tailscale.com v1.40.1 h1:NdIUKoD6DHXZY7SnMN85ERPbXZsx6ipiRa6odnrYZtU=