static final int IN = 0x0001;
    static final int A = 0x0001;
    static final int NS = 0x0002;
    static final int NULL = 0x000a;

    static final int HEADER_LENGTH = 12;

    // header field offsets
    static final int OPCODE_OFFSET = 2;
    static final int QUESTION_OFFSET = 4;
    static final int ANSWER_OFFSET = 6;
    static final int AUTHORITY_OFFSET = 8;
    static final int ADDITIONAL_OFFSET = 10;

    static final int IN        = 0x0001;
    static final int A         = 0x0001;
    static final int NS        = 0x0002;
    static final int NULL      = 0x000a;

    static final int HEADER_LENGTH = 12;

    // header field offsets
    static final int OPCODE_OFFSET = 2;
    static final int QUESTION_OFFSET = 4;
    static final int ANSWER_OFFSET = 6;
    static final int AUTHORITY_OFFSET = 8;
    static final int ADDITIONAL_OFFSET = 10;

이 경우, 프론트엔드가 제대로 동작하기 위해 `http://localhost:8080`을 목록에 포함해야 합니다.

## 와일드카드

모든 출처를 허용하기 위해 목록을 `"*"` ("와일드카드")로 선언하는 것도 가능합니다.

하지만 이것은 특정한 유형의 통신만을 허용하며, 쿠키 및 액세스 토큰과 사용되는 인증 헤더(Authoriztion header) 등이 포함된 경우와 같이 자격 증명(credentials)이 포함된 통신은 허용되지 않습니다.

따라서 모든 작업을 의도한대로 실행하기 위해, 허용되는 출처를 명시적으로 지정하는 것이 좋습니다.

## `CORSMiddleware` 사용

`CORSMiddleware` 을 사용하여 **FastAPI** 응용 프로그램의 교차 출처 리소스 공유 환경을 설정할 수 있습니다.

    * <abbr title="en anglais : path parameters">les paramètres du chemin</abbr>.
    * <abbr title="en anglais : query parameters">les paramètres de la requête</abbr>.
    * les cookies.
    * <abbr title="en anglais : headers">les en-têtes</abbr>.
    * <abbr title="en anglais : forms">les formulaires</abbr>.
    * <abbr title="en anglais : files">les fichiers</abbr>.

     * key and value, which we pass to the superconstructor, even though the key and value type for
     * a given entry might not include null. The right fix for the header problems is probably to
     * define a separate MultimapLink interface with a separate "header" implementation, which
     * hopefully could avoid implementing Entry or ValueSetLink at all. (But note that that approach

    * JSON.
    * Pfad-Parametern.
    * Abfrage-Parametern.
    * Cookies.
    * Header-Feldern.
    * Formularen.
    * Dateien.
* <abbr title="auch bekannt als: Serialisierung, Parsen, Marshalling">Konvertierung</abbr> von Ausgabedaten: Konvertierung von Python-Daten und -Typen zu Netzwerkdaten (als JSON):

Also fügen wir sie in ihr eigenes `dependencies`-Modul (`app/dependencies.py`) ein.

Wir werden nun eine einfache Abhängigkeit verwenden, um einen benutzerdefinierten `X-Token`-Header zu lesen:

//// tab | Python 3.9+

```Python hl_lines="3  6-8" title="app/dependencies.py"
{!> ../../docs_src/bigger_applications/app_an_py39/dependencies.py!}
```

////

//// tab | Python 3.8+

    * JSON.
    * <abbr title="Yol: Path">Yol</abbr> parametrləri.
    * <abbr title="Sorğu: Query">Sorğu</abbr> parametrləri.
    * <abbr title="Çərəz: Cookie">Çərəzlər</abbr>.
    * <abbr title="Başlıq: Header">Başlıqlaq</abbr>.
    * <abbr title="Forma: Form">Formalar</abbr>.
    * Fayllar.

* **Soporte en el editor**.
* **Type checks**.

...y **FastAPI** usa las mismas declaraciones para:

* **Definir requerimientos**: desde request path parameters, query parameters, headers, bodies, dependencies, etc.
* **Convertir datos**: desde el request al tipo requerido.
* **Validar datos**: viniendo de cada request:
    * Generando **errores automáticos** devueltos al cliente cuando los datos son inválidos.

                      type: object
                    rewrite:
                      description: Rewrite HTTP URIs and Authority headers.
                      properties:
                        authority:
                          description: rewrite the Authority/Host header with this
                            value.
                          type: string
                        uri: