* [X-Forwarded-Host](https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/X-Forwarded-Host)

///

然而，因為**應用伺服器**並不知道自己在受信任的**代理**之後，預設情況下它不會信任這些標頭。

但你可以設定**應用伺服器**去信任由**代理**送來的「轉發」標頭。若你使用 FastAPI CLI，可以用 *CLI 參數* `--forwarded-allow-ips` 指定應信任哪些 IP 來的「轉發」標頭。

例如，如果**應用伺服器**只會接收來自受信任**代理**的連線，你可以設定 `--forwarded-allow-ips="*"`，也就是信任所有來源 IP，因為實際上它只會收到**代理**那個 IP 送來的請求。

        // 127.0.0.1 is configured as a trusted proxy by default
        final MockletHttpServletRequest request = getMockRequest();
        request.setRemoteAddr("127.0.0.1");
        request.addHeader("X-Forwarded-For", "203.0.113.50, 70.41.3.18, 150.172.238.178");
        assertEquals("203.0.113.50", rateLimitHelper.getClientIp(request));
    }

    @Test
    public void test_getClientIp_xRealIp_trustedProxy() {

   * X-Forwarded-Host}</a> header field name.
   *
   * @since 20.0
   */
  public static final String X_FORWARDED_HOST = "X-Forwarded-Host";

  /**
   * The HTTP <a
   * href="https://docs.aws.amazon.com/elasticloadbalancing/latest/classic/x-forwarded-headers.html#x-forwarded-port">{@code
   * X-Forwarded-Port}</a> header field name.
   *
   * @since 20.0
   */

* [X-Forwarded-Proto](https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/X-Forwarded-Proto)
* [X-Forwarded-Host](https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/X-Forwarded-Host)

///

それでも、**アプリケーションサーバー**は信頼できる**プロキシ**の背後にあることを知らないため、デフォルトではそれらのヘッダーを信頼しません。

         proxy_buffering off;

        location / {
            proxy_set_header Host $http_host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;

            proxy_connect_timeout 300;
            # Default is HTTP/1, keepalive is only enabled in HTTP/1.1
            proxy_http_version 1.1;

 * interface-specific subclass of {@code ForwardingObject}, such as {@link ForwardingList}, to
 * preserve equality behavior, or override {@code equals} directly.
 *
 * <p>The {@code toString} method is forwarded to the delegate. Although this class does not
 * implement {@link Serializable}, a serializable subclass may be created since this class has a
 * parameter-less constructor.
 *
 * @author Mike Bostock
 * @since 2.0
 */

        if (isTrustedProxy(remoteAddr)) {
            final String xForwardedFor = request.getHeader("X-Forwarded-For");
            if (StringUtil.isNotBlank(xForwardedFor)) {
                final String clientIp = xForwardedFor.split(",")[0].trim();
                if (logger.isDebugEnabled()) {
                    logger.debug("Client IP from X-Forwarded-For: clientIp={}, remoteAddr={}", clientIp, remoteAddr);
                }

 * interface-specific subclass of {@code ForwardingObject}, such as {@link ForwardingList}, to
 * preserve equality behavior, or override {@code equals} directly.
 *
 * <p>The {@code toString} method is forwarded to the delegate. Although this class does not
 * implement {@link Serializable}, a serializable subclass may be created since this class has a
 * parameter-less constructor.
 *
 * @author Mike Bostock
 * @since 2.0
 */

        UserInfoHelper userInfoHelper = new UserInfoHelper();
        userInfoHelper.setCookieSecure(null);

        MockletHttpServletRequest request = getMockRequest();
        request.addHeader("X-Forwarded-Proto", "https");

        assertTrue(userInfoHelper.isSecureCookie());
    }

    @Test
    public void test_isSecureCookie_noRequest() {
        UserInfoHelper userInfoHelper = new UserInfoHelper();

		t.opts = opts
	})
}

// GetWithCtx will return a cached value or fetch a new one.
// passes a caller context, if caller context cancels nothing
// is cached.
// If the Update function returns an error the value is forwarded as is and not cached.
func (t *Cache[T]) GetWithCtx(ctx context.Context) (T, error) {
	v := t.val.Load()
	ttl := t.ttl
	vTime := t.lastUpdateMs.Load()
	tNow := time.Now().UnixMilli()