swarm: add mock net.PacketConn for testing

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 {
+		*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{BasicHost: h, Addr: publicAddr}
+	}
+
+	var peers []TestHost
+	for i := 0; i < identify.ActivationThresh; i++ {
+		h := newHost(fmt.Sprintf("peer-%d", i))
+		h.Start()
+		peers = append(peers, h)
+	}
 
+	h := newHost("host")
+	h.Start()
+	for _, p := range peers {
+		ctx := network.WithDialPeerTimeout(context.Background(), 1*time.Second)
+		h.Peerstore().AddAddr(p.ID(), p.Addr, peerstore.TempAddrTTL)
+		err := h.Connect(ctx, peer.AddrInfo{ID: p.ID()})
+		if err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	require.Eventually(t,
+		func() bool {
+			return ma.Contains(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
@@ -175,10 +192,11 @@ 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)
 		}
+		t.Cleanup(func() { reuse.Close() })
 		quicTransport, err := quic.NewTransport(priv, reuse, nil, cfg.connectionGater, nil)
 		if err != nil {
 			t.Fatal(err)
@@ -187,8 +205,14 @@ 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 +222,22 @@ 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()