# Django 4.1.8.dev20230308103347 ドキュメント

# ミドルウェア

This document explains all middleware components that come with Django. For information on how to use them and how to write your own middleware, see the middleware usage guide.

## 使用できる middleware

### Cache middleware

class `UpdateCacheMiddleware`

class `FetchFromCacheMiddleware`

サイト全体でキャッシュを有効にします。有効にすると、Django を利用している各ページは `CACHE_MIDDLEWARE_SECONDS` 設定で指定した時間だけキャッシュされます。詳しくは the cache documentation を読んでください。

### Common middleware

class `CommonMiddleware`

完璧主義者のためにいくつかの便利な機能を提供します。

- `DISALLOWED_USER_AGENTS` 設定に含まれるユーザーエージェントのアクセスを禁止します。この設定は、コンパイルした正規表現オブジェクトのリストである必要があります。

- `APPEND_SLASH` および `PREPEND_WWW` 設定に基づいて、URL の書き換えを実行します。

  `APPEND_SLASH` が `True` で、与えられた URL がスラッシュで終わっていなくて、さらに URLconf に URL が見つからなければ、Django は / が最後に追加された新しい URL を作り、この新しい URL へリクエストをリダイレクトします。それ以外のときには、最初の URL を通常通りに処理します。

  たとえば、 `foo.com/bar` は、 `foo.com/bar` に対する有効な URL パタンがなく、`foo.com/bar/` に対しては有効なパタンが 存在する 場合に、 `foo.com/bar/` にリダイレクトされます。

  `PREPEND_WWW` を `True` にすると、先頭に "www." がない URL は "www." で始まる同じ URL にリダイレクトされます。

  2つのオプションが意味するのは、URL を正規化するということです。これは、1つの URL には1つの、かつただ1つだけの場所を指すべきだという考えです。技術的には URL `foo.com/bar` は `foo.com/bar/` とは区別されます。実際、サーチエンジンのインデクスはこれらを区別して作成されます。よって、URL を正規化するというのがベストプラクティスなのです。

  If necessary, individual views may be excluded from the `APPEND_SLASH` behavior using the `no_append_slash()` decorator:

      from django.views.decorators.common import no_append_slash

      @no_append_slash
      def sensitive_fbv(request, *args, **kwargs):
          """View to be excluded from APPEND_SLASH."""
          return HttpResponse()

- Sets the `Content-Length` header for non-streaming responses.

`CommonMiddleware.``response_redirect_class`

Defaults to `HttpResponsePermanentRedirect`. Subclass `CommonMiddleware` and override the attribute to customize the redirects issued by the middleware.

class `BrokenLinkEmailsMiddleware`

- Sends broken link notification emails to `MANAGERS` (see How to manage error reporting).

### GZip middleware

class `GZipMiddleware`

警告

Security researchers recently revealed that when compression techniques (including `GZipMiddleware`) are used on a website, the site may become exposed to a number of possible attacks. Before using `GZipMiddleware` on your site, you should consider very carefully whether you are subject to these attacks. If you're in any doubt about whether you're affected, you should avoid using `GZipMiddleware`. For more details, see the the BREACH paper (PDF) and breachattack.com.

The `django.middleware.gzip.GZipMiddleware` compresses content for browsers that understand GZip compression (all modern browsers).

This middleware should be placed before any other middleware that need to read or write the response body so that compression happens afterward.

It will NOT compress content if any of the following are true:

- The content body is less than 200 bytes long.
- The response has already set the `Content-Encoding` header.
- The request (the browser) hasn't sent an `Accept-Encoding` header containing `gzip`.

If the response has an `ETag` header, the ETag is made weak to comply with RFC 7232#section-2.1.

You can apply GZip compression to individual views using the `gzip_page()` decorator.

### Conditional GET middleware

class `ConditionalGetMiddleware`

Handles conditional GET operations. If the response doesn't have an `ETag` header, the middleware adds one if needed. If the response has an `ETag` or `Last-Modified` header, and the request has `If-None-Match` or `If-Modified-Since`, the response is replaced by an `HttpResponseNotModified`.

### Locale ミドルウェア

class `LocaleMiddleware`

リクエストからのデータに基づいた言語セクションを有効化します。この機能は、それぞれのユーザに対してコンテンツをカスタマイズします。 国際化のドキュメント を参照してください。

`LocaleMiddleware.``response_redirect_class`

デフォルトは `HttpResponseRedirect` です。`LocaleMiddleware` をサブクラス化して属性をオーバーライドし、ミドルウェアによって発行されたリダイレクトをカスタマイズします。

### Message ミドルウェア

class `MessageMiddleware`

クッキーおよびセッションをベースとしたメッセージサポートを有効化します。メッセージのドキュメント を参照してください。

### Security middleware

警告

If your deployment situation allows, it's usually a good idea to have your front-end web server perform the functionality provided by the `SecurityMiddleware`. That way, if there are requests that aren't served by Django (such as static media or user-uploaded files), they will have the same protections as requests to your Django application.

class `SecurityMiddleware`

The `django.middleware.security.SecurityMiddleware` provides several security enhancements to the request/response cycle. Each one can be independently enabled or disabled with a setting.

- `SECURE_CONTENT_TYPE_NOSNIFF`
- `SECURE_CROSS_ORIGIN_OPENER_POLICY`
- `SECURE_HSTS_INCLUDE_SUBDOMAINS`
- `SECURE_HSTS_PRELOAD`
- `SECURE_HSTS_SECONDS`
- `SECURE_REDIRECT_EXEMPT`
- `SECURE_REFERRER_POLICY`
- `SECURE_SSL_HOST`
- `SECURE_SSL_REDIRECT`

#### HTTP Strict Transport Security

For sites that should only be accessed over HTTPS, you can instruct modern browsers to refuse to connect to your domain name via an insecure connection (for a given period of time) by setting the "Strict-Transport-Security" header. This reduces your exposure to some SSL-stripping man-in-the-middle (MITM) attacks.

`SecurityMiddleware` will set this header for you on all HTTPS responses if you set the `SECURE_HSTS_SECONDS` setting to a non-zero integer value.

When enabling HSTS, it's a good idea to first use a small value for testing, for example, `SECURE_HSTS_SECONDS = 3600` for one hour. Each time a web browser sees the HSTS header from your site, it will refuse to communicate non-securely (using HTTP) with your domain for the given period of time. Once you confirm that all assets are served securely on your site (i.e. HSTS didn't break anything), it's a good idea to increase this value so that infrequent visitors will be protected (31536000 seconds, i.e. 1 year, is common).

Additionally, if you set the `SECURE_HSTS_INCLUDE_SUBDOMAINS` setting to `True`, `SecurityMiddleware` will add the `includeSubDomains` directive to the `Strict-Transport-Security` header. This is recommended (assuming all subdomains are served exclusively using HTTPS), otherwise your site may still be vulnerable via an insecure connection to a subdomain.

If you wish to submit your site to the browser preload list, set the `SECURE_HSTS_PRELOAD` setting to `True`. That appends the `preload` directive to the `Strict-Transport-Security` header.

警告

The HSTS policy applies to your entire domain, not just the URL of the response that you set the header on. Therefore, you should only use it if your entire domain is served via HTTPS only.

Browsers properly respecting the HSTS header will refuse to allow users to bypass warnings and connect to a site with an expired, self-signed, or otherwise invalid SSL certificate. If you use HSTS, make sure your certificates are in good shape and stay that way!

注釈

If you are deployed behind a load-balancer or reverse-proxy server, and the `Strict-Transport-Security` header is not being added to your responses, it may be because Django doesn't realize that it's on a secure connection; you may need to set the `SECURE_PROXY_SSL_HEADER` setting.

#### Referrer Policy

Browsers use the Referer header as a way to send information to a site about how users got there. When a user clicks a link, the browser will send the full URL of the linking page as the referrer. While this can be useful for some purposes -- like figuring out who's linking to your site -- it also can cause privacy concerns by informing one site that a user was visiting another site.

Some browsers have the ability to accept hints about whether they should send the HTTP `Referer` header when a user clicks a link; this hint is provided via the Referrer-Policy header. This header can suggest any of three behaviors to browsers:

- Full URL: send the entire URL in the `Referer` header. For example, if the user is visiting `https://example.com/page.html`, the `Referer` header would contain `"https://example.com/page.html"`.
- Origin only: send only the "origin" in the referrer. The origin consists of the scheme, host and (optionally) port number. For example, if the user is visiting `https://example.com/page.html`, the origin would be `https://example.com/`.
- No referrer: do not send a `Referer` header at all.

There are two types of conditions this header can tell a browser to watch out for:

- Same-origin versus cross-origin: a link from `https://example.com/1.html` to `https://example.com/2.html` is same-origin. A link from `https://example.com/page.html` to `https://not.example.com/page.html` is cross-origin.
- Protocol downgrade: a downgrade occurs if the page containing the link is served via HTTPS, but the page being linked to is not served via HTTPS.

警告

When your site is served via HTTPS, Django's CSRF protection system requires the `Referer` header to be present, so completely disabling the `Referer` header will interfere with CSRF protection. To gain most of the benefits of disabling `Referer` headers while also keeping CSRF protection, consider enabling only same-origin referrers.

`SecurityMiddleware` can set the `Referrer-Policy` header for you, based on the `SECURE_REFERRER_POLICY` setting (note spelling: browsers send a `Referer` header when a user clicks a link, but the header instructing a browser whether to do so is spelled `Referrer-Policy`). The valid values for this setting are:

`no-referrer`
  Instructs the browser to send no referrer for links clicked on this site.
`no-referrer-when-downgrade`
  Instructs the browser to send a full URL as the referrer, but only when no protocol downgrade occurs.
`origin`
  Instructs the browser to send only the origin, not the full URL, as the referrer.
`origin-when-cross-origin`
  Instructs the browser to send the full URL as the referrer for same-origin links, and only the origin for cross-origin links.
`same-origin`
  Instructs the browser to send a full URL, but only for same-origin links. No referrer will be sent for cross-origin links.
`strict-origin`
  Instructs the browser to send only the origin, not the full URL, and to send no referrer when a protocol downgrade occurs.
`strict-origin-when-cross-origin`
  Instructs the browser to send the full URL when the link is same-origin and no protocol downgrade occurs; send only the origin when the link is cross-origin and no protocol downgrade occurs; and no referrer when a protocol downgrade occurs.
`unsafe-url`
  Instructs the browser to always send the full URL as the referrer.

Unknown Policy Values

Where a policy value is unknown by a user agent, it is possible to specify multiple policy values to provide a fallback. The last specified value that is understood takes precedence. To support this, an iterable or comma-separated string can be used with `SECURE_REFERRER_POLICY`.

#### Cross-Origin Opener Policy

New in Django 4.0.

Some browsers have the ability to isolate top-level windows from other documents by putting them in a separate browsing context group based on the value of the Cross-Origin Opener Policy (COOP) header. If a document that is isolated in this way opens a cross-origin popup window, the popup’s `window.opener` property will be `null`. Isolating windows using COOP is a defense-in-depth protection against cross-origin attacks, especially those like Spectre which allowed exfiltration of data loaded into a shared browsing context.

`SecurityMiddleware` can set the `Cross-Origin-Opener-Policy` header for you, based on the `SECURE_CROSS_ORIGIN_OPENER_POLICY` setting. The valid values for this setting are:

`same-origin`
  Isolates the browsing context exclusively to same-origin documents. Cross-origin documents are not loaded in the same browsing context. This is the default and most secure option.
`same-origin-allow-popups`
  Isolates the browsing context to same-origin documents or those which either don't set COOP or which opt out of isolation by setting a COOP of `unsafe-none`.
`unsafe-none`
  Allows the document to be added to its opener's browsing context group unless the opener itself has a COOP of `same-origin` or `same-origin-allow-popups`.

#### `X-Content-Type-Options: nosniff`

Some browsers will try to guess the content types of the assets that they fetch, overriding the `Content-Type` header. While this can help display sites with improperly configured servers, it can also pose a security risk.

If your site serves user-uploaded files, a malicious user could upload a specially-crafted file that would be interpreted as HTML or JavaScript by the browser when you expected it to be something harmless.

To prevent the browser from guessing the content type and force it to always use the type provided in the `Content-Type` header, you can pass the X-Content-Type-Options: nosniff header. `SecurityMiddleware` will do this for all responses if the `SECURE_CONTENT_TYPE_NOSNIFF` setting is `True`.

Note that in most deployment situations where Django isn't involved in serving user-uploaded files, this setting won't help you. For example, if your `MEDIA_URL` is served directly by your front-end web server (nginx, Apache, etc.) then you'd want to set this header there. On the other hand, if you are using Django to do something like require authorization in order to download files and you cannot set the header using your web server, this setting will be useful.

#### SSL リダイレクト

サイトが HTTP と HTTPS 接続の両方をサポートしている場合、多くのユーザーはデフォルトでセキュアでない接続を行ってしまいます。最善のセキュリティのためには、すべての HTTP 接続を HTTPS 接続にリダイレクトするべきです。

`SECURE_SSL_REDIRECT` 設定を True に設定すれば、 `SecurityMiddleware` が すべての HTTP 接続を HTTPS に parmanent (HTTP 301) にリダイレクトしてくれます。

注釈

パフォーマンス上の理由により、このようなリダイレクトは Django の外部、フロントエンドのロードバランサーや nginx などのリバースプロキシサーバーで実行した方が良いです。 `SECURE_SSL_REDIRECT` は、これらのオプションが使用できないデプロイ環境で使われることを想定しています。

If the `SECURE_SSL_HOST` setting has a value, all redirects will be sent to that host instead of the originally-requested host.

If there are a few pages on your site that should be available over HTTP, and not redirected to HTTPS, you can list regular expressions to match those URLs in the `SECURE_REDIRECT_EXEMPT` setting.

注釈

If you are deployed behind a load-balancer or reverse-proxy server and Django can't seem to tell when a request actually is already secure, you may need to set the `SECURE_PROXY_SSL_HEADER` setting.

### Session middleware

class `SessionMiddleware`

セッションのサポートを有効にします。詳しくは セッションのドキュメント を読んでください。

### Site middleware

class `CurrentSiteMiddleware`

受信側のすべての `HttpRequest` オブジェクトに、現在のサイトを表す `site` 属性を追加します。詳しくは sites documentation を読んでください。

### Authentication middleware

class `AuthenticationMiddleware`

Adds the `user` attribute, representing the currently-logged-in user, to every incoming `HttpRequest` object. See Authentication in web requests.

class `RemoteUserMiddleware`

Middleware for utilizing web server provided authentication. See How to authenticate using REMOTE_USER for usage details.

class `PersistentRemoteUserMiddleware`

Middleware for utilizing web server provided authentication when enabled only on the login page. See ログインページでのみ REMOTE_USER を使用する for usage details.

### CSRF プロテクション middleware

class `CsrfViewMiddleware`

POST フォームに隠しフォームフィールドを追加し、リクエストの値が正しいかチェックすることで、Cross Site Request Forgery に対するプロテクションを追加します。詳しくは Cross Site Request Forgery プロテクションのドキュメント を読んでください。

### `X-Frame-Options` middleware

class `XFrameOptionsMiddleware`

シンプルな クリックジャッキングに対する X-Frame-Options ヘッダ経由のプロテクション です。

## Middleware の順序

Django の多様なミドルウェアクラスの順序に関する注意点を挙げておきます。

1. `SecurityMiddleware`

   SSL リダイレクトを有効にしているなら、他のたくさんの必要のないミドルウェアが実行されないように、リストの先頭付近に置くべきです。

2. `UpdateCacheMiddleware`

   `Vary` ヘッダに変更を加えるミドルウェア (`SessionMiddleware`, `GZipMiddleware`, `LocaleMiddleware`) の前に置きます。

3. `GZipMiddleware`

   response body を変更・使用する可能性のあるミドルウェアの前に置きます。

   `Vary` ヘッダを修正するため、 `UpdateCacheMiddleware` の後に置きます。

4. `SessionMiddleware`

   Before any middleware that may raise an exception to trigger an error view (such as `PermissionDenied`) if you're using `CSRF_USE_SESSIONS`.

   `Vary` ヘッダを修正するため、 `UpdateCacheMiddleware` の後に置きます。

5. `ConditionalGetMiddleware`

   Before any middleware that may change the response (it sets the `ETag` header).

   gzip されたコンテンツに対して `ETag` ヘッダを計算しないように、 `GZipMiddleware` の後に置きます。

6. `LocaleMiddleware`

   `SessionMiddleware` (session データを使う) と `UpdateCacheMiddleware` (`Vary` ヘッダを修正する) の後のできるだけ高い位置に置きます。

7. `CommonMiddleware`

   Before any middleware that may change the response (it sets the `Content-Length` header). A middleware that appears before `CommonMiddleware` and changes the response must reset `Content-Length`.

   `APPEND_SLASH` か `PREPEND_WWW` が `True` に設定されているとリダイレクトされるので、先頭の近くに置きます。

   After `SessionMiddleware` if you're using `CSRF_USE_SESSIONS`.

8. `CsrfViewMiddleware`

   CSRF 攻撃が可能なすべての view ミドルウェアの前に置きます。

   Before `RemoteUserMiddleware`, or any other authentication middleware that may perform a login, and hence rotate the CSRF token, before calling down the middleware chain.

   After `SessionMiddleware` if you're using `CSRF_USE_SESSIONS`.

9. `AuthenticationMiddleware`

   session ストレージを使うので、 `SessionMiddleware` の後に置きます。

10. `MessageMiddleware`

    After `SessionMiddleware`: can use session-based storage.

11. `FetchFromCacheMiddleware`

    キャッシュのハッシュキーを生成するのに `Vary` ヘッダを使用するため、このヘッダを修正するすべてのミドルウェアのあとに置きます。

12. `FlatpageFallbackMiddleware`

    最後に実行されるタイプのミドルウェアなので、できるだけ下に置く必要があります。

13. `RedirectFallbackMiddleware`

    最後に実行されるタイプのミドルウェアなので、できるだけ下に置く必要があります。