chore: listening tcp together for dns server (#1792)

common/sockopt/reuse_common.go

@@ -0,0 +1,30 @@
+package sockopt
+
+import (
+	"net"
+	"syscall"
+)
+
+func RawConnReuseaddr(rc syscall.RawConn) (err error) {
+	var innerErr error
+	err = rc.Control(func(fd uintptr) {
+		innerErr = reuseControl(fd)
+	})
+
+	if innerErr != nil {
+		err = innerErr
+	}
+	return
+}
+
+func UDPReuseaddr(c net.PacketConn) error {
+	if c, ok := c.(syscall.Conn); ok {
+		rc, err := c.SyscallConn()
+		if err != nil {
+			return err
+		}
+
+		return RawConnReuseaddr(rc)
+	}
+	return nil
+}