added the ListenConfig and Setsockopt for additional unix environments

conn.go

@@ -73,9 +73,22 @@ func (c *connections) Add() error {
 	var err error
 	var conn net.PacketConn
 
-	if runtime.GOOS == "linux" {
-		conn, err = c.linuxListenPacket()
-	} else {
+	switch runtime.GOOS {
+	case "android":
+		fallthrough
+	case "linux":
+		fallthrough
+	case "darwin":
+		fallthrough
+	case "freebsd":
+		fallthrough
+	case "netbsd":
+		fallthrough
+	case "openbsd":
+		fallthrough
+	case "solaris":
+		conn, err = c.unixListenPacket()
+	default:
 		conn, err = net.ListenPacket("udp", ":0")
 	}
 
@@ -87,7 +100,7 @@ func (c *connections) Add() error {
 	return err
 }
 
-func (c *connections) linuxListenPacket() (net.PacketConn, error) {
+func (c *connections) unixListenPacket() (net.PacketConn, error) {
 	lc := net.ListenConfig{
 		Control: func(network, address string, c syscall.RawConn) error {
 			var operr error

xchg.go

@@ -62,13 +62,6 @@ func xchgKey(id uint16, name string) string {
 	return fmt.Sprintf("%d:%s", id, strings.ToLower(RemoveLastDot(name)))
 }
 
-func (r *xchgMgr) len() int {
-	r.Lock()
-	defer r.Unlock()
-
-	return len(r.xchgs)
-}
-
 func (r *xchgMgr) setTimeout(d time.Duration) {
 	r.Lock()
 	defer r.Unlock()