basichost: allow overriding Addrs()

p2p/host/basic/basic_host.go

@@ -23,6 +23,10 @@ var log = logging.Logger("basichost")
 
 var NegotiateTimeout = time.Second * 60
 
+// AddrsFactory functions can be passed to New in order to override
+// addresses returned by Addrs.
+type AddrsFactory func([]ma.Multiaddr) []ma.Multiaddr
+
 // Option is a type used to pass in options to the host.
 type Option int
 
@@ -45,6 +49,7 @@ type BasicHost struct {
 	mux     *msmux.MultistreamMuxer
 	ids     *identify.IDService
 	natmgr  *natManager
+	addrs   AddrsFactory
 
 	NegotiateTimeout time.Duration
 
@@ -72,6 +77,9 @@ func New(net inet.Network, opts ...interface{}) *BasicHost {
 	// setup host services
 	h.ids = identify.NewIDService(h)
 
+	// default addresses factory, can be overridden via opts argument
+	h.addrs = func(addrs []ma.Multiaddr) []ma.Multiaddr { return addrs }
+
 	for _, o := range opts {
 		switch o := o.(type) {
 		case Option:
@@ -81,6 +89,8 @@ func New(net inet.Network, opts ...interface{}) *BasicHost {
 			}
 		case metrics.Reporter:
 			h.bwc = o
+		case AddrsFactory:
+			h.addrs = AddrsFactory(o)
 		}
 	}
 
@@ -336,9 +346,15 @@ func (h *BasicHost) dialPeer(ctx context.Context, p peer.ID) error {
 	return nil
 }
 
-// Addrs returns all the addresses of BasicHost at this moment in time.
-// It's ok to not include addresses if they're not available to be used now.
+// Addrs returns listening addresses that are safe to announce to the network.
+// The output is the same as AllAddrs, but processed by AddrsFactory.
 func (h *BasicHost) Addrs() []ma.Multiaddr {
+	return h.addrs(h.AllAddrs())
+}
+
+// AllAddrs returns all the addresses of BasicHost at this moment in time.
+// It's ok to not include addresses if they're not available to be used now.
+func (h *BasicHost) AllAddrs() []ma.Multiaddr {
 	addrs, err := h.Network().InterfaceListenAddresses()
 	if err != nil {
 		log.Debug("error retrieving network interface addrs")

p2p/host/basic/basic_host_test.go

@@ -11,6 +11,7 @@ import (
 	inet "github.com/libp2p/go-libp2p-net"
 	testutil "github.com/libp2p/go-libp2p-netutil"
 	protocol "github.com/libp2p/go-libp2p-protocol"
+	ma "github.com/multiformats/go-multiaddr"
 )
 
 func TestHostSimple(t *testing.T) {
@@ -63,6 +64,25 @@ func TestHostSimple(t *testing.T) {
 	}
 }
 
+func TestHostAddrsFactory(t *testing.T) {
+	maddr := ma.StringCast("/ip4/1.2.3.4/tcp/1234")
+	addrsFactory := func(addrs []ma.Multiaddr) []ma.Multiaddr {
+		return []ma.Multiaddr{maddr}
+	}
+
+	ctx := context.Background()
+	h := New(testutil.GenSwarmNetwork(t, ctx), AddrsFactory(addrsFactory))
+	defer h.Close()
+
+	addrs := h.Addrs()
+	if len(addrs) != 1 {
+		t.Fatalf("expected 1 addr, got %d", len(addrs))
+	}
+	if addrs[0] != maddr {
+		t.Fatalf("expected %s, got %s", maddr.String(), addrs[0].String())
+	}
+}
+
 func getHostPair(ctx context.Context, t *testing.T) (host.Host, host.Host) {
 	h1 := New(testutil.GenSwarmNetwork(t, ctx))
 	h2 := New(testutil.GenSwarmNetwork(t, ctx))