code: func (t *dialTask) dial(srv *Server, dest *enode.Node) error {
  	fd, err := srv.Dialer.Dial(dest)
  	if err != nil {
  		return &dialError{err}
  	}
  	mfd := newMeteredConn(fd, false, dest.IP())
  	return srv.SetupConn(mfd, t.flags, dest)
  }
docs: // dial performs the actual connection attempt.