Adding MapPort function to BasicHost

core/host/host.go

@@ -5,6 +5,7 @@ package host
 
 import (
 	"context"
+	"net"
 
 	"github.com/libp2p/go-libp2p/core/connmgr"
 	"github.com/libp2p/go-libp2p/core/event"
@@ -72,4 +73,7 @@ type Host interface {
 
 	// EventBus returns the hosts eventbus
 	EventBus() event.Bus
+
+	// MapPort is a utility function that attempts to set up a port mapping
+	MapPort(protocol string, internalPort int) (net.Addr, int, error)
 }

p2p/host/basic/basic_host.go

@@ -1125,6 +1125,21 @@ func (h *BasicHost) Close() error {
 	return nil
 }
 
+func (h *BasicHost) MapPort(protocol string, internalPort int) (net.Addr, int, error) {
+	for h.natmgr == nil || h.natmgr.NAT() == nil {
+		time.Sleep(time.Millisecond * 100)
+	}
+	mapping, err := h.natmgr.NAT().NewMapping(protocol, internalPort)
+	if err != nil {
+		return nil, 0, err
+	}
+	addr, err := mapping.ExternalAddr()
+	if err != nil {
+		return nil, 0, err
+	}
+	return addr, mapping.ExternalPort(), nil
+}
+
 type streamWrapper struct {
 	network.Stream
 	rw io.ReadWriteCloser

p2p/host/basic/natmgr.go

@@ -14,6 +14,12 @@ import (
 	ma "github.com/multiformats/go-multiaddr"
 )
 
+// discoveryNATPeriod is the period at which we try to discover NATs.
+var discoveryNATPeriod = 3 * time.Second
+
+// discoveryTry is the number of times we try to discover NATs.
+const discoveryTry = 5
+
 // NATManager is a simple interface to manage NAT devices.
 type NATManager interface {
 	// NAT gets the NAT device managed by the NAT manager.
@@ -88,11 +94,20 @@ func (nmgr *natManager) background(ctx context.Context) {
 
 	discoverCtx, cancel := context.WithTimeout(ctx, 10*time.Second)
 	defer cancel()
+	tryCount := 0
 	natInstance, err := inat.DiscoverNAT(discoverCtx)
-	if err != nil {
+	tryCount++
+	for err != nil {
 		log.Info("DiscoverNAT error:", err)
-		close(nmgr.ready)
-		return
+		if tryCount > discoveryTry {
+			log.Info("DiscoverNAT failed after ", tryCount, " tries")
+			return
+		}
+		time.Sleep(discoveryNATPeriod)
+		discoverCtx, cancel := context.WithTimeout(ctx, 10*time.Second)
+		defer cancel()
+		natInstance, err = inat.DiscoverNAT(discoverCtx)
+		tryCount++
 	}
 
 	nmgr.natMx.Lock()

p2p/host/blank/blank.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"net"
 
 	"github.com/libp2p/go-libp2p/core/connmgr"
 	"github.com/libp2p/go-libp2p/core/event"
@@ -227,3 +228,7 @@ func (bh *BlankHost) ConnManager() connmgr.ConnManager {
 func (bh *BlankHost) EventBus() event.Bus {
 	return bh.eventbus
 }
+
+func (bh *BlankHost) MapPort(protocol string, internalPort int) (net.Addr, int, error) {
+	return nil, 0, nil
+}

p2p/host/routed/routed.go

@@ -3,6 +3,7 @@ package routedhost
 import (
 	"context"
 	"fmt"
+	"net"
 	"time"
 
 	"github.com/libp2p/go-libp2p/core/connmgr"
@@ -219,4 +220,8 @@ func (rh *RoutedHost) ConnManager() connmgr.ConnManager {
 	return rh.host.ConnManager()
 }
 
+func (rh *RoutedHost) MapPort(protocol string, internalPort int) (net.Addr, int, error) {
+	return rh.host.MapPort(protocol, internalPort)
+}
+
 var _ (host.Host) = (*RoutedHost)(nil)