使 Go App 使用 DNS over TLS

func newResolver(serverName string, addr string) *net.Resolver {
	var dialer net.Dialer
	tlsConfig := &tls.Config{
		ServerName: serverName,
		ClientSessionCache: tls.NewLRUClientSessionCache(32),

		InsecureSkipVerify: false,
	}

	return &net.Resolver{
		PreferGo: true,
		Dial: func (context context.Context, _, address string) (net.Conn, error) {
			conn, err := dialer.DialContext(context, "tcp", addr)
			if err != nil {
				return nil, err
			}

			_ = conn.(*net.TCPConn).SetKeepAlive(true)
			_ = conn.(*net.TCPConn).SetKeepAlivePeriod(10 * time.Minute)
			return tls.Client(conn, tlsConfig), nil
		},
	}

}

func init() {
	net.DefaultResolver = newResolver('cloudflare-dns.com', '1.0.0.1:853')
}