feat: switch to go-netroute

This library makes the correct syscalls instead of shelling out to a binary.

gateway.go

+package nat
+
+import (
+	"net"
+
+	"github.com/libp2p/go-netroute"
+)
+
+func getDefaultGateway() (net.IP, error) {
+	router, err := netroute.New()
+	if err != nil {
+		return nil, err
+	}
+
+	_, ip, _, err := router.Route(net.IPv4zero)
+	return ip, err
+}

go.mod

@@ -2,9 +2,9 @@ module github.com/libp2p/go-nat
 
 require (
 	github.com/huin/goupnp v1.0.0
-	github.com/jackpal/gateway v1.0.5
 	github.com/jackpal/go-nat-pmp v1.0.2
 	github.com/koron/go-ssdp v0.0.0-20191105050749-2e1c40ed0b5d
+	github.com/libp2p/go-netroute v0.1.2
 )
 
 go 1.12

go.sum

+github.com/google/gopacket v1.1.17 h1:rMrlX2ZY2UbvT+sdz3+6J+pp2z+msCq9MxTU6ymxbBY=
+github.com/google/gopacket v1.1.17/go.mod h1:UdDNZ1OO62aGYVnPhxT1U6aI7ukYtA/kB8vaU0diBUM=
 github.com/huin/goupnp v1.0.0 h1:wg75sLpL6DZqwHQN6E1Cfk6mtfzS45z8OV+ic+DtHRo=
 github.com/huin/goupnp v1.0.0/go.mod h1:n9v9KO1tAxYH82qOn+UTIFQDmx5n1Zxd/ClZDMX7Bnc=
 github.com/huin/goutil v0.0.0-20170803182201-1ca381bf3150/go.mod h1:PpLOETDnJ0o3iZrZfqZzyLl6l7F3c6L1oWn7OICBi6o=
-github.com/jackpal/gateway v1.0.5 h1:qzXWUJfuMdlLMtt0a3Dgt+xkWQiA5itDEITVJtuSwMc=
-github.com/jackpal/gateway v1.0.5/go.mod h1:lTpwd4ACLXmpyiCTRtfiNyVnUmqT9RivzCDQetPfnjA=
-github.com/jackpal/go-nat-pmp v1.0.1 h1:i0LektDkO1QlrTm/cSuP+PyBCDnYvjPLGl4LdWEMiaA=
-github.com/jackpal/go-nat-pmp v1.0.1/go.mod h1:QPH045xvCAeXUZOxsnwmrtiCoxIr9eob+4orBN1SBKc=
 github.com/jackpal/go-nat-pmp v1.0.2 h1:KzKSgb7qkJvOUTqYl9/Hg/me3pWgBmERKrTGD7BdWus=
 github.com/jackpal/go-nat-pmp v1.0.2/go.mod h1:QPH045xvCAeXUZOxsnwmrtiCoxIr9eob+4orBN1SBKc=
 github.com/koron/go-ssdp v0.0.0-20191105050749-2e1c40ed0b5d h1:68u9r4wEvL3gYg2jvAOgROwZ3H+Y3hIDk4tbbmIjcYQ=
 github.com/koron/go-ssdp v0.0.0-20191105050749-2e1c40ed0b5d/go.mod h1:5Ky9EC2xfoUKUor0Hjgi2BJhCSXJfMOFlmyYrVKGQMk=
+github.com/libp2p/go-netroute v0.1.2 h1:UHhB35chwgvcRI392znJA3RCBtZ3MpE3ahNCN5MR4Xg=
+github.com/libp2p/go-netroute v0.1.2/go.mod h1:jZLDV+1PE8y5XxBySEBgbuVAXbhtuHSdmLPL2n9MKbk=
+github.com/libp2p/go-sockaddr v0.0.2 h1:tCuXfpA9rq7llM/v834RKc/Xvovy/AqM9kHvTV/jY/Q=
+github.com/libp2p/go-sockaddr v0.0.2/go.mod h1:syPvOmNs24S3dFVGJA1/mrqdeijPxLV2Le3BRLKd68k=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/net v0.0.0-20181011144130-49bb7cea24b1 h1:Y/KGZSOdz/2r0WJ9Mkmz6NJBusp0kiNx1Cn82lzJQ6w=
 golang.org/x/net v0.0.0-20181011144130-49bb7cea24b1/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3 h1:0GoQqolDA55aaLxZyTzK/Y2ePZzZTUrRacwib7cNsYQ=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190228124157-a34e9553db1e/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190405154228-4b34438f7a67 h1:1Fzlr8kkDLQwqMP8GxrhptBLqZG/EDpiATneiZHY998=
+golang.org/x/sys v0.0.0-20190405154228-4b34438f7a67/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.3.0 h1:g61tztE5qeGQ89tm6NTjjM9VPIm088od1l6aSorWRWg=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=

nat.go

@@ -8,8 +8,6 @@ import (
 	"math/rand"
 	"net"
 	"time"
-
-	"github.com/jackpal/gateway"
 )
 
 var ErrNoExternalAddress = errors.New("no external address")
@@ -101,7 +99,7 @@ func DiscoverGateway() (NAT, error) {
 	case 1:
 		return nats[0], nil
 	}
-	gw, _ := gateway.DiscoverGateway()
+	gw, _ := getDefaultGateway()
 	bestNAT := nats[0]
 	natGw, _ := bestNAT.GetDeviceAddress()
 	bestNATIsGw := gw != nil && natGw.Equal(gw)

natpmp.go

@@ -5,7 +5,6 @@ import (
 	"net"
 	"time"
 
-	"github.com/jackpal/gateway"
 	"github.com/jackpal/go-nat-pmp"
 )
 
@@ -16,24 +15,24 @@ var (
 func discoverNATPMP(ctx context.Context) <-chan NAT {
 	res := make(chan NAT, 1)
 
-	ip, err := gateway.DiscoverGateway()
-	if err == nil {
-		go func() {
-			defer close(res)
-			// Unfortunately, we can't actually _stop_ the natpmp
-			// library. However, we can at least close _our_ channel
-			// and walk away.
-			select {
-			case client, ok := <-discoverNATPMPWithAddr(ip):
-				if ok {
-					res <- &natpmpNAT{client, ip, make(map[int]int)}
-				}
-			case <-ctx.Done():
-			}
-		}()
-	} else {
-		close(res)
+	ip, err := getDefaultGateway()
+	if err != nil {
+		return nil
 	}
+
+	go func() {
+		defer close(res)
+		// Unfortunately, we can't actually _stop_ the natpmp
+		// library. However, we can at least close _our_ channel
+		// and walk away.
+		select {
+		case client, ok := <-discoverNATPMPWithAddr(ip):
+			if ok {
+				res <- &natpmpNAT{client, ip, make(map[int]int)}
+			}
+		case <-ctx.Done():
+		}
+	}()
 	return res
 }