add IsPrivateAddr

private.go

@@ -61,6 +61,21 @@ func IsPublicAddr(a ma.Multiaddr) bool {
 	return false
 }
 
+// IsPrivateAddr returns true if the IP part of the mutiadr is in a private network
+func IsPrivateAddr(a ma.Multiaddr) bool {
+	ip, err := a.ValueForProtocol(ma.P_IP4)
+	if err == nil {
+		return inAddrRange(ip, Private4)
+	}
+
+	ip, err = a.ValueForProtocol(ma.P_IP6)
+	if err == nil {
+		return inAddrRange(ip, Private6)
+	}
+
+	return false
+}
+
 func inAddrRange(s string, ipnets []*net.IPNet) bool {
 	ip := net.ParseIP(s)
 	for _, ipnet := range ipnets {

private_test.go

@@ -16,6 +16,10 @@ func TestIsPublicAddr(t *testing.T) {
 		t.Fatal("192.168.1.1 is not a public address!")
 	}
 
+	if !IsPrivateAddr(a) {
+		t.Fatal("192.168.1.1 is a private address!")
+	}
+
 	a, err = ma.NewMultiaddr("/ip4/1.1.1.1/tcp/80")
 	if err != nil {
 		t.Fatal(err)
@@ -24,4 +28,8 @@ func TestIsPublicAddr(t *testing.T) {
 	if !IsPublicAddr(a) {
 		t.Fatal("1.1.1.1 is a public address!")
 	}
+
+	if IsPrivateAddr(a) {
+		t.Fatal("1.1.1.1 is not a private address!")
+	}
 }