ToNetAddr + tests.

net.go

@@ -65,6 +65,27 @@ func FromNetAddr(a net.Addr) (Multiaddr, error) {
 	}
 }
 
+// ToNetAddr converts a Multiaddr to a net.Addr
+// Must be ThinWaist. acceptable protocol stacks are:
+// /ip{4,6}/{tcp, udp}
+func ToNetAddr(ma Multiaddr) (net.Addr, error) {
+	network, host, err := DialArgs(ma)
+	if err != nil {
+		return nil, err
+	}
+
+	switch network {
+	case "tcp":
+		return net.ResolveTCPAddr(network, host)
+	case "udp":
+		return net.ResolveUDPAddr(network, host)
+	case "ip":
+		return net.ResolveIPAddr(network, host)
+	}
+
+	return nil, fmt.Errorf("network not supported: %s", network)
+}
+
 // FromIP converts a net.IP type to a Multiaddr.
 func FromIP(ip net.IP) (Multiaddr, error) {
 	switch {
@@ -85,8 +106,12 @@ func DialArgs(m Multiaddr) (string, string, error) {
 
 	str := m.String()
 	parts := strings.Split(str, "/")[1:]
-	network := parts[2]
 
+	if len(parts) == 2 { // only IP
+		return parts[0], parts[1], nil
+	}
+
+	network := parts[2]
 	var host string
 	switch parts[0] {
 	case "ip4":
@@ -98,16 +123,28 @@ func DialArgs(m Multiaddr) (string, string, error) {
 }
 
 // IsThinWaist returns whether a Multiaddr starts with "Thin Waist" Protocols.
-// This means: /{IP4, IP6}/{TCP, UDP}
+// This means: /{IP4, IP6}[/{TCP, UDP}]
 func IsThinWaist(m Multiaddr) bool {
 	p := m.Protocols()
+
+	// nothing? not even a waist.
+	if len(p) == 0 {
+		return false
+	}
+
 	if p[0].Code != P_IP4 && p[0].Code != P_IP6 {
 		return false
 	}
 
-	if p[1].Code != P_TCP && p[1].Code != P_UDP {
-		return false
+	// only IP? still counts.
+	if len(p) == 1 {
+		return true
 	}
 
-	return true
+	switch p[1].Code {
+	case P_TCP, P_UDP, P_IP4, P_IP6:
+		return true
+	default:
+		return false
+	}
 }

net_test.go

@@ -18,6 +18,44 @@ func testConvert(t *testing.T, s string, gen GenFunc) {
 	}
 }
 
+func testToNetAddr(t *testing.T, maddr, ntwk, addr string) {
+	m, err := NewMultiaddr(maddr)
+	if err != nil {
+		t.Fatal("failed to generate.")
+	}
+
+	naddr, err := ToNetAddr(m)
+	if addr == "" { // should fail
+		if err == nil {
+			t.Fatalf("failed to error: %s", m)
+		}
+		return
+	}
+
+	// shouldn't fail
+	if err != nil {
+		t.Fatalf("failed to convert to net addr: %s", m)
+	}
+
+	if naddr.String() != addr {
+		t.Fatalf("naddr.Address() == %s != %s", naddr, addr)
+	}
+
+	if naddr.Network() != ntwk {
+		t.Fatalf("naddr.Network() == %s != %s", naddr.Network(), ntwk)
+	}
+
+	// should convert properly
+	switch ntwk {
+	case "tcp":
+		_ = naddr.(*net.TCPAddr)
+	case "udp":
+		_ = naddr.(*net.UDPAddr)
+	case "ip":
+		_ = naddr.(*net.IPAddr)
+	}
+}
+
 func TestFromIP4(t *testing.T) {
 	testConvert(t, "/ip4/10.20.30.40", func() (Multiaddr, error) {
 		return FromIP(net.ParseIP("10.20.30.40"))
@@ -48,6 +86,34 @@ func TestFromUDP(t *testing.T) {
 	})
 }
 
+func TestThinWaist(t *testing.T) {
+	addrs := map[string]bool{
+		"/ip4/127.0.0.1/udp/1234":              true,
+		"/ip4/127.0.0.1/tcp/1234":              true,
+		"/ip4/127.0.0.1/udp/1234/tcp/1234":     true,
+		"/ip4/127.0.0.1/tcp/12345/ip4/1.2.3.4": true,
+		"/ip6/::1/tcp/80":                      true,
+		"/ip6/::1/udp/80":                      true,
+		"/ip6/::1":                             true,
+		"/tcp/1234/ip4/1.2.3.4":                false,
+		"/tcp/1234":                            false,
+		"/tcp/1234/udp/1234":                   false,
+		"/ip4/1.2.3.4/ip4/2.3.4.5":             true,
+		"/ip6/::1/ip4/2.3.4.5":                 true,
+	}
+
+	for a, res := range addrs {
+		ma, err := NewMultiaddr(a)
+		if err != nil {
+			t.Fatalf("failed to construct Multiaddr: %s", a)
+		}
+
+		if IsThinWaist(ma) != res {
+			t.Fatalf("IsThinWaist(%s) != %v", a, res)
+		}
+	}
+}
+
 func TestDialArgs(t *testing.T) {
 	m, err := NewMultiaddr("/ip4/127.0.0.1/udp/1234")
 	if err != nil {