adding UserAgent to Nat for description of port mapping

config/config.go

@@ -47,7 +47,7 @@ import (
 type AddrsFactory = bhost.AddrsFactory
 
 // NATManagerC is a NATManager constructor.
-type NATManagerC func(network.Network) bhost.NATManager
+type NATManagerC func(network.Network, ...bhost.Option) (bhost.NATManager, error)
 
 type RoutingC func(host.Host) (routing.PeerRouting, error)
 

p2p/host/basic/basic_host.go

@@ -129,7 +129,7 @@ type HostOpts struct {
 
 	// NATManager takes care of setting NAT port mappings, and discovering external addresses.
 	// If omitted, this will simply be disabled.
-	NATManager func(network.Network) NATManager
+	NATManager func(network.Network, ...Option) (NATManager, error)
 
 	// ConnManager is a libp2p connection manager
 	ConnManager connmgr.ConnManager
@@ -272,7 +272,11 @@ func NewHost(n network.Network, opts *HostOpts) (*BasicHost, error) {
 	}
 
 	if opts.NATManager != nil {
-		h.natmgr = opts.NATManager(n)
+		natmgr, err := opts.NATManager(n, WithUserAgent(opts.UserAgent))
+		if err != nil {
+			return nil, fmt.Errorf("failed to create NAT manager: %w", err)
+		}
+		h.natmgr = natmgr
 	}
 
 	if opts.MultiaddrResolver != nil {

p2p/host/basic/natmgr.go

@@ -2,6 +2,7 @@ package basichost
 
 import (
 	"context"
+	"fmt"
 	"io"
 	"net"
 	"net/netip"
@@ -26,8 +27,8 @@ type NATManager interface {
 }
 
 // NewNATManager creates a NAT manager.
-func NewNATManager(net network.Network) NATManager {
-	return newNATManager(net)
+func NewNATManager(net network.Network, opt ...Option) (NATManager, error) {
+	return newNATManager(net, opt...)
 }
 
 type entry struct {
@@ -43,7 +44,13 @@ type nat interface {
 }
 
 // so we can mock it in tests
-var discoverNAT = func(ctx context.Context) (nat, error) { return inat.DiscoverNAT(ctx) }
+var discoverNAT = func(ctx context.Context, userAgent string) (nat, error) {
+	if userAgent != "" {
+		return inat.DiscoverNATWithUserAgent(ctx, userAgent)
+	} else {
+		return inat.DiscoverNAT(ctx)
+	}
+}
 
 // natManager takes care of adding + removing port mappings to the nat.
 // Initialized with the host if it has a NATPortMap option enabled.
@@ -56,6 +63,8 @@ type natManager struct {
 	natMx sync.RWMutex
 	nat   nat
 
+	userAgent string
+
 	syncFlag chan struct{} // cap: 1
 
 	tracked map[entry]bool // the bool is only used in doSync and has no meaning outside of that function
@@ -65,7 +74,7 @@ type natManager struct {
 	ctxCancel context.CancelFunc
 }
 
-func newNATManager(net network.Network) *natManager {
+func newNATManager(net network.Network, opts ...Option) (*natManager, error) {
 	ctx, cancel := context.WithCancel(context.Background())
 	nmgr := &natManager{
 		net:       net,
@@ -74,9 +83,17 @@ func newNATManager(net network.Network) *natManager {
 		ctxCancel: cancel,
 		tracked:   make(map[entry]bool),
 	}
+
+	for _, opt := range opts {
+		err := opt(nmgr)
+		if err != nil {
+			return nil, fmt.Errorf("error applying NAT manager option: %w", err)
+		}
+	}
+
 	nmgr.refCount.Add(1)
 	go nmgr.background(ctx)
-	return nmgr
+	return nmgr, nil
 }
 
 // Close closes the natManager, closing the underlying nat
@@ -107,7 +124,7 @@ func (nmgr *natManager) background(ctx context.Context) {
 
 	discoverCtx, cancel := context.WithTimeout(ctx, 10*time.Second)
 	defer cancel()
-	natInstance, err := discoverNAT(discoverCtx)
+	natInstance, err := discoverNAT(discoverCtx, nmgr.userAgent)
 	if err != nil {
 		log.Info("DiscoverNAT error:", err)
 		return

p2p/host/basic/natmgr_test.go

@@ -20,7 +20,7 @@ func setupMockNAT(t *testing.T) (mockNAT *MockNAT, reset func()) {
 	ctrl := gomock.NewController(t)
 	mockNAT = NewMockNAT(ctrl)
 	origDiscoverNAT := discoverNAT
-	discoverNAT = func(ctx context.Context) (nat, error) { return mockNAT, nil }
+	discoverNAT = func(ctx context.Context, userAgent string) (nat, error) { return mockNAT, nil }
 	return mockNAT, func() {
 		discoverNAT = origDiscoverNAT
 		ctrl.Finish()
@@ -33,7 +33,8 @@ func TestMapping(t *testing.T) {
 
 	sw := swarmt.GenSwarm(t)
 	defer sw.Close()
-	m := newNATManager(sw)
+	m, err := newNATManager(sw)
+	require.NoError(t, err)
 	require.Eventually(t, func() bool {
 		m.natMx.Lock()
 		defer m.natMx.Unlock()
@@ -67,7 +68,8 @@ func TestAddAndRemoveListeners(t *testing.T) {
 
 	sw := swarmt.GenSwarm(t)
 	defer sw.Close()
-	m := newNATManager(sw)
+	m, err := newNATManager(sw)
+	require.NoError(t, err)
 	require.Eventually(t, func() bool {
 		m.natMx.Lock()
 		defer m.natMx.Unlock()

p2p/host/basic/options.go

@@ -0,0 +1,13 @@
+package basichost
+
+type Option func(*natManager) error
+
+// WithUserAgent is a natManager option that sets specific user agent for the NAT manager.
+func WithUserAgent(userAgent string) Option {
+	return func(nmgr *natManager) error {
+		if userAgent != "" {
+			nmgr.userAgent = userAgent
+		}
+		return nil
+	}
+}

p2p/net/nat/nat.go

@@ -33,8 +33,12 @@ type entry struct {
 // so we can mock it in tests
 var discoverGateway = nat.DiscoverGateway
 
-// DiscoverNAT looks for a NAT device in the network and returns an object that can manage port mappings.
 func DiscoverNAT(ctx context.Context) (*NAT, error) {
+	return DiscoverNATWithUserAgent(ctx, "libp2p")
+}
+
+// DiscoverNATWithUserAgent looks for a NAT device in the network and returns an object that can manage port mappings.
+func DiscoverNATWithUserAgent(ctx context.Context, userAgent string) (*NAT, error) {
 	natInstance, err := discoverGateway(ctx)
 	if err != nil {
 		return nil, err
@@ -60,6 +64,7 @@ func DiscoverNAT(ctx context.Context) (*NAT, error) {
 		mappings:  make(map[entry]int),
 		ctx:       ctx,
 		ctxCancel: cancel,
+		userAgent: userAgent,
 	}
 	nat.refCount.Add(1)
 	go func() {
@@ -77,7 +82,8 @@ type NAT struct {
 	natmu sync.Mutex
 	nat   nat.NAT
 	// External IP of the NAT. Will be renewed periodically (every CacheTime).
-	extAddr netip.Addr
+	extAddr   netip.Addr
+	userAgent string
 
 	refCount  sync.WaitGroup
 	ctx       context.Context
@@ -222,14 +228,13 @@ func (nat *NAT) background() {
 
 func (nat *NAT) establishMapping(ctx context.Context, protocol string, internalPort int) (externalPort int) {
 	log.Debugf("Attempting port map: %s/%d", protocol, internalPort)
-	const comment = "libp2p"
 
 	nat.natmu.Lock()
 	var err error
-	externalPort, err = nat.nat.AddPortMapping(ctx, protocol, internalPort, comment, MappingDuration)
+	externalPort, err = nat.nat.AddPortMapping(ctx, protocol, internalPort, nat.userAgent, MappingDuration)
 	if err != nil {
 		// Some hardware does not support mappings with timeout, so try that
-		externalPort, err = nat.nat.AddPortMapping(ctx, protocol, internalPort, comment, 0)
+		externalPort, err = nat.nat.AddPortMapping(ctx, protocol, internalPort, nat.userAgent, 0)
 	}
 	nat.natmu.Unlock()