# documentação Django 2.0.8

# Código fonte para django.middleware.clickjacking

    """
    Clickjacking Protection Middleware.

    This module provides a middleware that implements protection against a
    malicious site loading resources from your site in a hidden frame.
    """

    from django.conf import settings
    from django.utils.deprecation import MiddlewareMixin

    class XFrameOptionsMiddleware(MiddlewareMixin):
        """
        Set the X-Frame-Options HTTP header in HTTP responses.

        Do not set the header if it's already set or if the response contains
        a xframe_options_exempt value set to True.

        By default, set the X-Frame-Options header to 'SAMEORIGIN', meaning the
        response can only be loaded on a frame within the same site. To prevent the
        response from being loaded in a frame in any site, set X_FRAME_OPTIONS in
        your project's Django settings to 'DENY'.
        """
        def process_response(self, request, response):
            # Don't set it if it's already in the response
            if response.get('X-Frame-Options') is not None:
                return response

            # Don't set it if they used @xframe_options_exempt
            if getattr(response, 'xframe_options_exempt', False):
                return response

            response['X-Frame-Options'] = self.get_xframe_options_value(request,
                                                                        response)
            return response

        def get_xframe_options_value(self, request, response):
            """
            Get the value to set for the X_FRAME_OPTIONS header. Use the value from
            the X_FRAME_OPTIONS setting, or 'SAMEORIGIN' if not set.

            This method can be overridden if needed, allowing it to vary based on
            the request or response.
            """
            return getattr(settings, 'X_FRAME_OPTIONS', 'SAMEORIGIN').upper()