django-cors-headers =================== A Django App that adds CORS (Cross-Origin Resource Sharing) headers to responses. Although JSON-P is useful, it is strictly limited to GET requests. CORS builds on top of ``XmlHttpRequest`` to allow developers to make cross-domain requests, similar to same-domain requests. Read more about it here: http://www.html5rocks.com/en/tutorials/cors/ .. image:: https://travis-ci.org/ottoyiu/django-cors-headers.svg?branch=master :target: https://travis-ci.org/ottoyiu/django-cors-headers Requirements ------------ Tested with all combinations of: * Python: 2.7, 3.5, 3.6, 3.7 * Django: 1.11, 2.0, 2.1, 2.2 Setup ----- Install from **pip**: .. code-block:: sh pip install django-cors-headers and then add it to your installed apps: .. code-block:: python INSTALLED_APPS = ( ... 'corsheaders', ... ) You will also need to add a middleware class to listen in on responses: .. code-block:: python MIDDLEWARE = [ # Or MIDDLEWARE_CLASSES on Django < 1.10 ... 'corsheaders.middleware.CorsMiddleware', 'django.middleware.common.CommonMiddleware', ... ] ``CorsMiddleware`` should be placed as high as possible, especially before any middleware that can generate responses such as Django's ``CommonMiddleware`` or Whitenoise's ``WhiteNoiseMiddleware``. If it is not before, it will not be able to add the CORS headers to these responses. Also if you are using ``CORS_REPLACE_HTTPS_REFERER`` it should be placed before Django's ``CsrfViewMiddleware`` (see more below). About ----- **django-cors-headers** was created in January 2013 by Otto Yiu. It went unmaintained from August 2015 and was forked in January 2016 to the package `django-cors-middleware `_ by Laville Augustin at Zeste de Savoir. In September 2016, Adam Johnson, Ed Morley, and others gained maintenance responsibility for **django-cors-headers** (`Issue 110 `_) from Otto Yiu. Basically all of the changes in the forked **django-cors-middleware** were merged back, or re-implemented in a different way, so it should be possible to switch back. If there's a feature that hasn't been merged, please open an issue about it. **django-cors-headers** has had `40+ contributors `_ in its time; thanks to every one of them. Configuration ------------- Configure the middleware's behaviour in your Django settings. You must add the hosts that are allowed to do cross-site requests to ``CORS_ORIGIN_WHITELIST``, or set ``CORS_ORIGIN_ALLOW_ALL`` to ``True`` to allow all hosts. ``CORS_ORIGIN_ALLOW_ALL`` ~~~~~~~~~~~~~~~~~~~~~~~~~ If ``True``, the whitelist will not be used and all origins will be accepted. Defaults to ``False``. ``CORS_ORIGIN_WHITELIST`` ~~~~~~~~~~~~~~~~~~~~~~~~~ A list of origin hostnames that are authorized to make cross-site HTTP requests. The value ``'null'`` can also appear in this list, and will match the ``Origin: null`` header that is used in `"privacy-sensitive contexts" `_, such as when the client is running from a ``file://`` domain. Defaults to ``[]``. Example: .. code-block:: python CORS_ORIGIN_WHITELIST = ( 'google.com', 'hostname.example.com', 'localhost:8000', '127.0.0.1:9000' ) ``CORS_ORIGIN_REGEX_WHITELIST`` ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ A list of regexes that match origin regex list of origin hostnames that are authorized to make cross-site HTTP requests. Defaults to ``[]``. Useful when ``CORS_ORIGIN_WHITELIST`` is impractical, such as when you have a large number of subdomains. Example: .. code-block:: python CORS_ORIGIN_REGEX_WHITELIST = (r'^(https?://)?(\w+\.)?google\.com$', ) -------------- The following are optional settings, for which the defaults probably suffice. ``CORS_URLS_REGEX`` ~~~~~~~~~~~~~~~~~~~ A regex which restricts the URL's for which the CORS headers will be sent. Defaults to ``r'^.*$'``, i.e. match all URL's. Useful when you only need CORS on a part of your site, e.g. an API at ``/api/``. Example: .. code-block:: python CORS_URLS_REGEX = r'^/api/.*$' ``CORS_ALLOW_METHODS`` ~~~~~~~~~~~~~~~~~~~~~~ A list of HTTP verbs that are allowed for the actual request. Defaults to: .. code-block:: python CORS_ALLOW_METHODS = ( 'DELETE', 'GET', 'OPTIONS', 'PATCH', 'POST', 'PUT', ) The default can be imported as ``corsheaders.defaults.default_methods`` so you can just extend it with your custom methods. This allows you to keep up to date with any future changes. For example: .. code-block:: python from corsheaders.defaults import default_methods CORS_ALLOW_METHODS = default_methods + ( 'POKE', ) ``CORS_ALLOW_HEADERS`` ~~~~~~~~~~~~~~~~~~~~~~ The list of non-standard HTTP headers that can be used when making the actual request. Defaults to: .. code-block:: python CORS_ALLOW_HEADERS = ( 'accept', 'accept-encoding', 'authorization', 'content-type', 'dnt', 'origin', 'user-agent', 'x-csrftoken', 'x-requested-with', ) The default can be imported as ``corsheaders.defaults.default_headers`` so you can extend it with your custom headers. This allows you to keep up to date with any future changes. For example: .. code-block:: python from corsheaders.defaults import default_headers CORS_ALLOW_HEADERS = default_headers + ( 'my-custom-header', ) ``CORS_EXPOSE_HEADERS`` ~~~~~~~~~~~~~~~~~~~~~~~ The list of HTTP headers that are to be exposed to the browser. Defaults to ``[]``. ``CORS_PREFLIGHT_MAX_AGE`` ~~~~~~~~~~~~~~~~~~~~~~~~~~ The number of seconds a client/browser can cache the preflight response. If this is 0 (or any falsey value), no max age header will be sent. Defaults to ``86400`` (one day). **Note:** A preflight request is an extra request that is made when making a "not-so-simple" request (e.g. ``Content-Type`` is not ``application/x-www-form-urlencoded``) to determine what requests the server actually accepts. Read more about it in the `HTML 5 Rocks CORS tutorial `_. ``CORS_ALLOW_CREDENTIALS`` ~~~~~~~~~~~~~~~~~~~~~~~~~~ If ``True``, cookies will be allowed to be included in cross-site HTTP requests. Defaults to ``False``. Note: in Django 2.1 the `SESSION_COOKIE_SAMESITE`_ setting was added, set to ``'Lax'`` by default, which will prevent Django's session cookie being sent cross-domain. Change it to ``None`` to bypass this security restriction. .. _SESSION_COOKIE_SAMESITE: https://docs.djangoproject.com/en/2.1/ref/settings/#std:setting-SESSION_COOKIE_SAMESITE ``CORS_MODEL`` ~~~~~~~~~~~~~~ If set, this should be the path to a model to look up allowed origins, in the form ``app.modelname``. Defaults to ``None``. The model should inherit from ``corsheaders.models.AbstractCorsModel`` and specify the allowed origin in the ``CharField`` called ``cors``. CSRF Integration ---------------- Most sites will need to take advantage of the `Cross-Site Request Forgery protection `_ that Django offers. CORS and CSRF are separate, and Django has no way of using your CORS configuration to exempt sites from the ``Referer`` checking that it does on secure requests. The way to do that is with its `CSRF_TRUSTED_ORIGINS setting `_. For example: .. code-block:: python CORS_ORIGIN_WHITELIST = ( 'read.only.com', 'change.allowed.com', ) CSRF_TRUSTED_ORIGINS = ( 'change.allowed.com', ) ``CORS_REPLACE_HTTPS_REFERER`` ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ``CSRF_TRUSTED_ORIGINS`` was introduced in Django 1.9, so users of earlier versions will need an alternate solution. If ``CORS_REPLACE_HTTPS_REFERER`` is ``True``, ``CorsMiddleware`` will change the ``Referer`` header to something that will pass Django's CSRF checks whenever the CORS checks pass. Defaults to ``False``. Note that unlike ``CSRF_TRUSTED_ORIGINS``, this setting does not allow you to distinguish between domains that are trusted to *read* resources by CORS and domains that are trusted to *change* resources by avoiding CSRF protection. With this feature enabled you should also add ``corsheaders.middleware.CorsPostCsrfMiddleware`` after ``django.middleware.csrf.CsrfViewMiddleware`` in your ``MIDDLEWARE_CLASSES`` to undo the ``Referer`` replacement: .. code-block:: python MIDDLEWARE_CLASSES = [ ... 'corsheaders.middleware.CorsMiddleware', ... 'django.middleware.csrf.CsrfViewMiddleware', 'corsheaders.middleware.CorsPostCsrfMiddleware', ... ] Signals ------- If you have a use case that requires more than just the above configuration, you can attach code to check if a given request should be allowed. For example, this can be used to read the list of origins you allow from a model. Attach any number of handlers to the ``check_request_enabled`` `Django signal `_, which provides the ``request`` argument (use ``**kwargs`` in your handler to protect against any future arguments being added). If any handler attached to the signal returns a truthy value, the request will be allowed. For example you might define a handler like this: .. code-block:: python # myapp/handlers.py from corsheaders.signals import check_request_enabled from .models import MySite def cors_allow_mysites(sender, request, **kwargs): return MySite.objects.filter(host=request.host).exists() check_request_enabled.connect(cors_allow_mysites) Then connect it at app ready time using a `Django AppConfig `_: .. code-block:: python # myapp/__init__.py default_app_config = 'myapp.apps.MyAppConfig' .. code-block:: python # myapp/apps.py from django.apps import AppConfig class MyAppConfig(AppConfig): name = 'myapp' def ready(self): # Makes sure all signal handlers are connected from . import handlers # noqa A common use case for the signal is to allow *all* origins to access a subset of URL's, whilst allowing a normal set of origins to access *all* URL's. This isn't possible using just the normal configuration, but it can be achieved with a signal handler. First set ``CORS_ORIGIN_WHITELIST`` to the list of trusted origins that are allowed to access every URL, and then add a handler to ``check_request_enabled`` to allow CORS regardless of the origin for the unrestricted URL's. For example: .. code-block:: python # myapp/handlers.py from corsheaders.signals import check_request_enabled def cors_allow_api_to_everyone(sender, request, **kwargs): return request.path.startswith('/api/') check_request_enabled.connect(cors_allow_api_to_everyone)