code: func listenerAddrEqual(ln net.Listener, addr string) bool {
  	lnAddr := ln.Addr().String()
  	hostname, port, err := net.SplitHostPort(addr)
  	if err != nil {
  		return lnAddr == addr
  	}
  	if lnAddr == net.JoinHostPort("::", port) {
  		return true
  	}
  	if lnAddr == net.JoinHostPort("0.0.0.0", port) {
  		return true
  	}
  	return hostname != "" && lnAddr == addr
  }
docs: // listenerAddrEqual compares a listener's address with
  // addr. Extra care is taken to match addresses with an
  // empty hostname portion, as listeners tend to report
  // [::]:80, for example, when the matching address that
  // created the listener might be simply :80.