django/tests/middleware/tests.py

import gzip
import random
import re
import struct
from io import BytesIO
from urllib.parse import quote

from django.conf import settings
from django.core import mail
from django.core.exceptions import PermissionDenied
from django.http import (
    FileResponse, HttpRequest, HttpResponse, HttpResponseNotFound,
    HttpResponsePermanentRedirect, HttpResponseRedirect, StreamingHttpResponse,
)
from django.middleware.clickjacking import XFrameOptionsMiddleware
from django.middleware.common import (
    BrokenLinkEmailsMiddleware, CommonMiddleware,
)
from django.middleware.gzip import GZipMiddleware
from django.middleware.http import ConditionalGetMiddleware
from django.test import RequestFactory, SimpleTestCase, override_settings

int2byte = struct.Struct(">B").pack


def get_response_empty(request):
    return HttpResponse()


def get_response_404(request):
    return HttpResponseNotFound()


@override_settings(ROOT_URLCONF='middleware.urls')
class CommonMiddlewareTest(SimpleTestCase):

    rf = RequestFactory()

    @override_settings(APPEND_SLASH=True)
    def test_append_slash_have_slash(self):
        """
        URLs with slashes should go unmolested.
        """
        request = self.rf.get('/slash/')
        self.assertIsNone(CommonMiddleware(get_response_404).process_request(request))
        self.assertEqual(CommonMiddleware(get_response_404)(request).status_code, 404)

    @override_settings(APPEND_SLASH=True)
    def test_append_slash_slashless_resource(self):
        """
        Matches to explicit slashless URLs should go unmolested.
        """
        def get_response(req):
            return HttpResponse("Here's the text of the Web page.")

        request = self.rf.get('/noslash')
        self.assertIsNone(CommonMiddleware(get_response).process_request(request))
        self.assertEqual(
            CommonMiddleware(get_response)(request).content,
            b"Here's the text of the Web page.",
        )

    @override_settings(APPEND_SLASH=True)
    def test_append_slash_slashless_unknown(self):
        """
        APPEND_SLASH should not redirect to unknown resources.
        """
        request = self.rf.get('/unknown')
        response = CommonMiddleware(get_response_404)(request)
        self.assertEqual(response.status_code, 404)

    @override_settings(APPEND_SLASH=True)
    def test_append_slash_redirect(self):
        """
        APPEND_SLASH should redirect slashless URLs to a valid pattern.
        """
        request = self.rf.get('/slash')
        r = CommonMiddleware(get_response_empty).process_request(request)
        self.assertEqual(r.status_code, 301)

    @override_settings(APPEND_SLASH=True)
    def test_append_slash_redirect_querystring(self):
        """
        APPEND_SLASH should preserve querystrings when redirecting.
        """
        request = self.rf.get('/slash?test=1')
        resp = CommonMiddleware(get_response_404)(request)
        self.assertEqual(resp.url, '/slash/?test=1')

    @override_settings(APPEND_SLASH=True)
    def test_append_slash_redirect_querystring_have_slash(self):
        """
        APPEND_SLASH should append slash to path when redirecting a request
        with a querystring ending with slash.
        """
        request = self.rf.get('/slash?test=slash/')
        resp = CommonMiddleware(get_response_404)(request)
        self.assertIsInstance(resp, HttpResponsePermanentRedirect)
        self.assertEqual(resp.url, '/slash/?test=slash/')

    @override_settings(APPEND_SLASH=True, DEBUG=True)
    def test_append_slash_no_redirect_on_POST_in_DEBUG(self):
        """
        While in debug mode, an exception is raised with a warning
        when a failed attempt is made to POST, PUT, or PATCH to an URL which
        would normally be redirected to a slashed version.
        """
        msg = "maintaining %s data. Change your form to point to testserver/slash/"
        request = self.rf.get('/slash')
        request.method = 'POST'
        with self.assertRaisesMessage(RuntimeError, msg % request.method):
            CommonMiddleware(get_response_404)(request)
        request = self.rf.get('/slash')
        request.method = 'PUT'
        with self.assertRaisesMessage(RuntimeError, msg % request.method):
            CommonMiddleware(get_response_404)(request)
        request = self.rf.get('/slash')
        request.method = 'PATCH'
        with self.assertRaisesMessage(RuntimeError, msg % request.method):
            CommonMiddleware(get_response_404)(request)

    @override_settings(APPEND_SLASH=False)
    def test_append_slash_disabled(self):
        """
        Disabling append slash functionality should leave slashless URLs alone.
        """
        request = self.rf.get('/slash')
        self.assertEqual(CommonMiddleware(get_response_404)(request).status_code, 404)

    @override_settings(APPEND_SLASH=True)
    def test_append_slash_opt_out(self):
        """
        Views marked with @no_append_slash should be left alone.
        """
        request = self.rf.get('/sensitive_fbv')
        self.assertEqual(CommonMiddleware(get_response_404)(request).status_code, 404)

        request = self.rf.get('/sensitive_cbv')
        self.assertEqual(CommonMiddleware(get_response_404)(request).status_code, 404)

    @override_settings(APPEND_SLASH=True)
    def test_append_slash_quoted(self):
        """
        URLs which require quoting should be redirected to their slash version.
        """
        request = self.rf.get(quote('/needsquoting#'))
        r = CommonMiddleware(get_response_404)(request)
        self.assertEqual(r.status_code, 301)
        self.assertEqual(r.url, '/needsquoting%23/')

    @override_settings(APPEND_SLASH=True)
    def test_append_slash_leading_slashes(self):
        """
        Paths starting with two slashes are escaped to prevent open redirects.
        If there's a URL pattern that allows paths to start with two slashes, a
        request with path //evil.com must not redirect to //evil.com/ (appended
        slash) which is a schemaless absolute URL. The browser would navigate
        to evil.com/.
        """
        # Use 4 slashes because of RequestFactory behavior.
        request = self.rf.get('////evil.com/security')
        r = CommonMiddleware(get_response_404).process_request(request)
        self.assertEqual(r.status_code, 301)
        self.assertEqual(r.url, '/%2Fevil.com/security/')
        r = CommonMiddleware(get_response_404)(request)
        self.assertEqual(r.status_code, 301)
        self.assertEqual(r.url, '/%2Fevil.com/security/')

    @override_settings(APPEND_SLASH=False, PREPEND_WWW=True)
    def test_prepend_www(self):
        request = self.rf.get('/path/')
        r = CommonMiddleware(get_response_empty).process_request(request)
        self.assertEqual(r.status_code, 301)
        self.assertEqual(r.url, 'http://www.testserver/path/')

    @override_settings(APPEND_SLASH=True, PREPEND_WWW=True)
    def test_prepend_www_append_slash_have_slash(self):
        request = self.rf.get('/slash/')
        r = CommonMiddleware(get_response_empty).process_request(request)
        self.assertEqual(r.status_code, 301)
        self.assertEqual(r.url, 'http://www.testserver/slash/')

    @override_settings(APPEND_SLASH=True, PREPEND_WWW=True)
    def test_prepend_www_append_slash_slashless(self):
        request = self.rf.get('/slash')
        r = CommonMiddleware(get_response_empty).process_request(request)
        self.assertEqual(r.status_code, 301)
        self.assertEqual(r.url, 'http://www.testserver/slash/')

    # The following tests examine expected behavior given a custom URLconf that
    # overrides the default one through the request object.

    @override_settings(APPEND_SLASH=True)
    def test_append_slash_have_slash_custom_urlconf(self):
        """
        URLs with slashes should go unmolested.
        """
        request = self.rf.get('/customurlconf/slash/')
        request.urlconf = 'middleware.extra_urls'
        self.assertIsNone(CommonMiddleware(get_response_404).process_request(request))
        self.assertEqual(CommonMiddleware(get_response_404)(request).status_code, 404)

    @override_settings(APPEND_SLASH=True)
    def test_append_slash_slashless_resource_custom_urlconf(self):
        """
        Matches to explicit slashless URLs should go unmolested.
        """
        def get_response(req):
            return HttpResponse("Web content")

        request = self.rf.get('/customurlconf/noslash')
        request.urlconf = 'middleware.extra_urls'
        self.assertIsNone(CommonMiddleware(get_response).process_request(request))
        self.assertEqual(CommonMiddleware(get_response)(request).content, b'Web content')

    @override_settings(APPEND_SLASH=True)
    def test_append_slash_slashless_unknown_custom_urlconf(self):
        """
        APPEND_SLASH should not redirect to unknown resources.
        """
        request = self.rf.get('/customurlconf/unknown')
        request.urlconf = 'middleware.extra_urls'
        self.assertIsNone(CommonMiddleware(get_response_404).process_request(request))
        self.assertEqual(CommonMiddleware(get_response_404)(request).status_code, 404)

    @override_settings(APPEND_SLASH=True)
    def test_append_slash_redirect_custom_urlconf(self):
        """
        APPEND_SLASH should redirect slashless URLs to a valid pattern.
        """
        request = self.rf.get('/customurlconf/slash')
        request.urlconf = 'middleware.extra_urls'
        r = CommonMiddleware(get_response_404)(request)
        self.assertIsNotNone(r, "CommonMiddleware failed to return APPEND_SLASH redirect using request.urlconf")
        self.assertEqual(r.status_code, 301)
        self.assertEqual(r.url, '/customurlconf/slash/')

    @override_settings(APPEND_SLASH=True, DEBUG=True)
    def test_append_slash_no_redirect_on_POST_in_DEBUG_custom_urlconf(self):
        """
        While in debug mode, an exception is raised with a warning
        when a failed attempt is made to POST to an URL which would normally be
        redirected to a slashed version.
        """
        request = self.rf.get('/customurlconf/slash')
        request.urlconf = 'middleware.extra_urls'
        request.method = 'POST'
        with self.assertRaisesMessage(RuntimeError, 'end in a slash'):
            CommonMiddleware(get_response_404)(request)

    @override_settings(APPEND_SLASH=False)
    def test_append_slash_disabled_custom_urlconf(self):
        """
        Disabling append slash functionality should leave slashless URLs alone.
        """
        request = self.rf.get('/customurlconf/slash')
        request.urlconf = 'middleware.extra_urls'
        self.assertIsNone(CommonMiddleware(get_response_404).process_request(request))
        self.assertEqual(CommonMiddleware(get_response_404)(request).status_code, 404)

    @override_settings(APPEND_SLASH=True)
    def test_append_slash_quoted_custom_urlconf(self):
        """
        URLs which require quoting should be redirected to their slash version.
        """
        request = self.rf.get(quote('/customurlconf/needsquoting#'))
        request.urlconf = 'middleware.extra_urls'
        r = CommonMiddleware(get_response_404)(request)
        self.assertIsNotNone(r, "CommonMiddleware failed to return APPEND_SLASH redirect using request.urlconf")
        self.assertEqual(r.status_code, 301)
        self.assertEqual(r.url, '/customurlconf/needsquoting%23/')

    @override_settings(APPEND_SLASH=False, PREPEND_WWW=True)
    def test_prepend_www_custom_urlconf(self):
        request = self.rf.get('/customurlconf/path/')
        request.urlconf = 'middleware.extra_urls'
        r = CommonMiddleware(get_response_empty).process_request(request)
        self.assertEqual(r.status_code, 301)
        self.assertEqual(r.url, 'http://www.testserver/customurlconf/path/')

    @override_settings(APPEND_SLASH=True, PREPEND_WWW=True)
    def test_prepend_www_append_slash_have_slash_custom_urlconf(self):
        request = self.rf.get('/customurlconf/slash/')
        request.urlconf = 'middleware.extra_urls'
        r = CommonMiddleware(get_response_empty).process_request(request)
        self.assertEqual(r.status_code, 301)
        self.assertEqual(r.url, 'http://www.testserver/customurlconf/slash/')

    @override_settings(APPEND_SLASH=True, PREPEND_WWW=True)
    def test_prepend_www_append_slash_slashless_custom_urlconf(self):
        request = self.rf.get('/customurlconf/slash')
        request.urlconf = 'middleware.extra_urls'
        r = CommonMiddleware(get_response_empty).process_request(request)
        self.assertEqual(r.status_code, 301)
        self.assertEqual(r.url, 'http://www.testserver/customurlconf/slash/')

    # Tests for the Content-Length header

    def test_content_length_header_added(self):
        def get_response(req):
            response = HttpResponse('content')
            self.assertNotIn('Content-Length', response)
            return response

        response = CommonMiddleware(get_response)(self.rf.get('/'))
        self.assertEqual(int(response.headers['Content-Length']), len(response.content))

    def test_content_length_header_not_added_for_streaming_response(self):
        def get_response(req):
            response = StreamingHttpResponse('content')
            self.assertNotIn('Content-Length', response)
            return response

        response = CommonMiddleware(get_response)(self.rf.get('/'))
        self.assertNotIn('Content-Length', response)

    def test_content_length_header_not_changed(self):
        bad_content_length = 500

        def get_response(req):
            response = HttpResponse()
            response.headers['Content-Length'] = bad_content_length
            return response

        response = CommonMiddleware(get_response)(self.rf.get('/'))
        self.assertEqual(int(response.headers['Content-Length']), bad_content_length)

    # Other tests

    @override_settings(DISALLOWED_USER_AGENTS=[re.compile(r'foo')])
    def test_disallowed_user_agents(self):
        request = self.rf.get('/slash')
        request.META['HTTP_USER_AGENT'] = 'foo'
        with self.assertRaisesMessage(PermissionDenied, 'Forbidden user agent'):
            CommonMiddleware(get_response_empty).process_request(request)

    def test_non_ascii_query_string_does_not_crash(self):
        """Regression test for #15152"""
        request = self.rf.get('/slash')
        request.META['QUERY_STRING'] = 'drink=café'
        r = CommonMiddleware(get_response_empty).process_request(request)
        self.assertEqual(r.status_code, 301)

    def test_response_redirect_class(self):
        request = self.rf.get('/slash')
        r = CommonMiddleware(get_response_404)(request)
        self.assertEqual(r.status_code, 301)
        self.assertEqual(r.url, '/slash/')
        self.assertIsInstance(r, HttpResponsePermanentRedirect)

    def test_response_redirect_class_subclass(self):
        class MyCommonMiddleware(CommonMiddleware):
            response_redirect_class = HttpResponseRedirect

        request = self.rf.get('/slash')
        r = MyCommonMiddleware(get_response_404)(request)
        self.assertEqual(r.status_code, 302)
        self.assertEqual(r.url, '/slash/')
        self.assertIsInstance(r, HttpResponseRedirect)


@override_settings(
    IGNORABLE_404_URLS=[re.compile(r'foo')],
    MANAGERS=[('PHD', 'PHB@dilbert.com')],
)
class BrokenLinkEmailsMiddlewareTest(SimpleTestCase):

    rf = RequestFactory()

    def setUp(self):
        self.req = self.rf.get('/regular_url/that/does/not/exist')

    def get_response(self, req):
        return self.client.get(req.path)

    def test_404_error_reporting(self):
        self.req.META['HTTP_REFERER'] = '/another/url/'
        BrokenLinkEmailsMiddleware(self.get_response)(self.req)
        self.assertEqual(len(mail.outbox), 1)
        self.assertIn('Broken', mail.outbox[0].subject)

    def test_404_error_reporting_no_referer(self):
        BrokenLinkEmailsMiddleware(self.get_response)(self.req)
        self.assertEqual(len(mail.outbox), 0)

    def test_404_error_reporting_ignored_url(self):
        self.req.path = self.req.path_info = 'foo_url/that/does/not/exist'
        BrokenLinkEmailsMiddleware(self.get_response)(self.req)
        self.assertEqual(len(mail.outbox), 0)

    def test_custom_request_checker(self):
        class SubclassedMiddleware(BrokenLinkEmailsMiddleware):
            ignored_user_agent_patterns = (re.compile(r'Spider.*'), re.compile(r'Robot.*'))

            def is_ignorable_request(self, request, uri, domain, referer):
                '''Check user-agent in addition to normal checks.'''
                if super().is_ignorable_request(request, uri, domain, referer):
                    return True
                user_agent = request.META['HTTP_USER_AGENT']
                return any(pattern.search(user_agent) for pattern in self.ignored_user_agent_patterns)

        self.req.META['HTTP_REFERER'] = '/another/url/'
        self.req.META['HTTP_USER_AGENT'] = 'Spider machine 3.4'
        SubclassedMiddleware(self.get_response)(self.req)
        self.assertEqual(len(mail.outbox), 0)
        self.req.META['HTTP_USER_AGENT'] = 'My user agent'
        SubclassedMiddleware(self.get_response)(self.req)
        self.assertEqual(len(mail.outbox), 1)

    def test_referer_equal_to_requested_url(self):
        """
        Some bots set the referer to the current URL to avoid being blocked by
        an referer check (#25302).
        """
        self.req.META['HTTP_REFERER'] = self.req.path
        BrokenLinkEmailsMiddleware(self.get_response)(self.req)
        self.assertEqual(len(mail.outbox), 0)

        # URL with scheme and domain should also be ignored
        self.req.META['HTTP_REFERER'] = 'http://testserver%s' % self.req.path
        BrokenLinkEmailsMiddleware(self.get_response)(self.req)
        self.assertEqual(len(mail.outbox), 0)

        # URL with a different scheme should be ignored as well because bots
        # tend to use http:// in referers even when browsing HTTPS websites.
        self.req.META['HTTP_X_PROTO'] = 'https'
        self.req.META['SERVER_PORT'] = 443
        with self.settings(SECURE_PROXY_SSL_HEADER=('HTTP_X_PROTO', 'https')):
            BrokenLinkEmailsMiddleware(self.get_response)(self.req)
        self.assertEqual(len(mail.outbox), 0)

    def test_referer_equal_to_requested_url_on_another_domain(self):
        self.req.META['HTTP_REFERER'] = 'http://anotherserver%s' % self.req.path
        BrokenLinkEmailsMiddleware(self.get_response)(self.req)
        self.assertEqual(len(mail.outbox), 1)

    @override_settings(APPEND_SLASH=True)
    def test_referer_equal_to_requested_url_without_trailing_slash_when_append_slash_is_set(self):
        self.req.path = self.req.path_info = '/regular_url/that/does/not/exist/'
        self.req.META['HTTP_REFERER'] = self.req.path_info[:-1]
        BrokenLinkEmailsMiddleware(self.get_response)(self.req)
        self.assertEqual(len(mail.outbox), 0)

    @override_settings(APPEND_SLASH=False)
    def test_referer_equal_to_requested_url_without_trailing_slash_when_append_slash_is_unset(self):
        self.req.path = self.req.path_info = '/regular_url/that/does/not/exist/'
        self.req.META['HTTP_REFERER'] = self.req.path_info[:-1]
        BrokenLinkEmailsMiddleware(self.get_response)(self.req)
        self.assertEqual(len(mail.outbox), 1)


@override_settings(ROOT_URLCONF='middleware.cond_get_urls')
class ConditionalGetMiddlewareTest(SimpleTestCase):
    request_factory = RequestFactory()

    def setUp(self):
        self.req = self.request_factory.get('/')
        self.resp_headers = {}

    def get_response(self, req):
        resp = self.client.get(req.path_info)
        for key, value in self.resp_headers.items():
            resp[key] = value
        return resp

    # Tests for the ETag header

    def test_middleware_calculates_etag(self):
        resp = ConditionalGetMiddleware(self.get_response)(self.req)
        self.assertEqual(resp.status_code, 200)
        self.assertNotEqual('', resp['ETag'])

    def test_middleware_wont_overwrite_etag(self):
        self.resp_headers['ETag'] = 'eggs'
        resp = ConditionalGetMiddleware(self.get_response)(self.req)
        self.assertEqual(resp.status_code, 200)
        self.assertEqual('eggs', resp['ETag'])

    def test_no_etag_streaming_response(self):
        def get_response(req):
            return StreamingHttpResponse(['content'])

        self.assertFalse(ConditionalGetMiddleware(get_response)(self.req).has_header('ETag'))

    def test_no_etag_response_empty_content(self):
        def get_response(req):
            return HttpResponse()

        self.assertFalse(ConditionalGetMiddleware(get_response)(self.req).has_header('ETag'))

    def test_no_etag_no_store_cache(self):
        self.resp_headers['Cache-Control'] = 'No-Cache, No-Store, Max-age=0'
        self.assertFalse(ConditionalGetMiddleware(self.get_response)(self.req).has_header('ETag'))

    def test_etag_extended_cache_control(self):
        self.resp_headers['Cache-Control'] = 'my-directive="my-no-store"'
        self.assertTrue(ConditionalGetMiddleware(self.get_response)(self.req).has_header('ETag'))

    def test_if_none_match_and_no_etag(self):
        self.req.META['HTTP_IF_NONE_MATCH'] = 'spam'
        resp = ConditionalGetMiddleware(self.get_response)(self.req)
        self.assertEqual(resp.status_code, 200)

    def test_no_if_none_match_and_etag(self):
        self.resp_headers['ETag'] = 'eggs'
        resp = ConditionalGetMiddleware(self.get_response)(self.req)
        self.assertEqual(resp.status_code, 200)

    def test_if_none_match_and_same_etag(self):
        self.req.META['HTTP_IF_NONE_MATCH'] = '"spam"'
        self.resp_headers['ETag'] = '"spam"'
        resp = ConditionalGetMiddleware(self.get_response)(self.req)
        self.assertEqual(resp.status_code, 304)

    def test_if_none_match_and_different_etag(self):
        self.req.META['HTTP_IF_NONE_MATCH'] = 'spam'
        self.resp_headers['ETag'] = 'eggs'
        resp = ConditionalGetMiddleware(self.get_response)(self.req)
        self.assertEqual(resp.status_code, 200)

    def test_if_none_match_and_redirect(self):
        def get_response(req):
            resp = self.client.get(req.path_info)
            resp['ETag'] = 'spam'
            resp['Location'] = '/'
            resp.status_code = 301
            return resp

        self.req.META['HTTP_IF_NONE_MATCH'] = 'spam'
        resp = ConditionalGetMiddleware(get_response)(self.req)
        self.assertEqual(resp.status_code, 301)

    def test_if_none_match_and_client_error(self):
        def get_response(req):
            resp = self.client.get(req.path_info)
            resp['ETag'] = 'spam'
            resp.status_code = 400
            return resp

        self.req.META['HTTP_IF_NONE_MATCH'] = 'spam'
        resp = ConditionalGetMiddleware(get_response)(self.req)
        self.assertEqual(resp.status_code, 400)

    # Tests for the Last-Modified header

    def test_if_modified_since_and_no_last_modified(self):
        self.req.META['HTTP_IF_MODIFIED_SINCE'] = 'Sat, 12 Feb 2011 17:38:44 GMT'
        resp = ConditionalGetMiddleware(self.get_response)(self.req)
        self.assertEqual(resp.status_code, 200)

    def test_no_if_modified_since_and_last_modified(self):
        self.resp_headers['Last-Modified'] = 'Sat, 12 Feb 2011 17:38:44 GMT'
        resp = ConditionalGetMiddleware(self.get_response)(self.req)
        self.assertEqual(resp.status_code, 200)

    def test_if_modified_since_and_same_last_modified(self):
        self.req.META['HTTP_IF_MODIFIED_SINCE'] = 'Sat, 12 Feb 2011 17:38:44 GMT'
        self.resp_headers['Last-Modified'] = 'Sat, 12 Feb 2011 17:38:44 GMT'
        self.resp = ConditionalGetMiddleware(self.get_response)(self.req)
        self.assertEqual(self.resp.status_code, 304)

    def test_if_modified_since_and_last_modified_in_the_past(self):
        self.req.META['HTTP_IF_MODIFIED_SINCE'] = 'Sat, 12 Feb 2011 17:38:44 GMT'
        self.resp_headers['Last-Modified'] = 'Sat, 12 Feb 2011 17:35:44 GMT'
        resp = ConditionalGetMiddleware(self.get_response)(self.req)
        self.assertEqual(resp.status_code, 304)

    def test_if_modified_since_and_last_modified_in_the_future(self):
        self.req.META['HTTP_IF_MODIFIED_SINCE'] = 'Sat, 12 Feb 2011 17:38:44 GMT'
        self.resp_headers['Last-Modified'] = 'Sat, 12 Feb 2011 17:41:44 GMT'
        self.resp = ConditionalGetMiddleware(self.get_response)(self.req)
        self.assertEqual(self.resp.status_code, 200)

    def test_if_modified_since_and_redirect(self):
        def get_response(req):
            resp = self.client.get(req.path_info)
            resp['Last-Modified'] = 'Sat, 12 Feb 2011 17:35:44 GMT'
            resp['Location'] = '/'
            resp.status_code = 301
            return resp

        self.req.META['HTTP_IF_MODIFIED_SINCE'] = 'Sat, 12 Feb 2011 17:38:44 GMT'
        resp = ConditionalGetMiddleware(get_response)(self.req)
        self.assertEqual(resp.status_code, 301)

    def test_if_modified_since_and_client_error(self):
        def get_response(req):
            resp = self.client.get(req.path_info)
            resp['Last-Modified'] = 'Sat, 12 Feb 2011 17:35:44 GMT'
            resp.status_code = 400
            return resp

        self.req.META['HTTP_IF_MODIFIED_SINCE'] = 'Sat, 12 Feb 2011 17:38:44 GMT'
        resp = ConditionalGetMiddleware(get_response)(self.req)
        self.assertEqual(resp.status_code, 400)

    def test_not_modified_headers(self):
        """
        The 304 Not Modified response should include only the headers required
        by section 4.1 of RFC 7232, Last-Modified, and the cookies.
        """
        def get_response(req):
            resp = self.client.get(req.path_info)
            resp['Date'] = 'Sat, 12 Feb 2011 17:35:44 GMT'
            resp['Last-Modified'] = 'Sat, 12 Feb 2011 17:35:44 GMT'
            resp['Expires'] = 'Sun, 13 Feb 2011 17:35:44 GMT'
            resp['Vary'] = 'Cookie'
            resp['Cache-Control'] = 'public'
            resp['Content-Location'] = '/alt'
            resp['Content-Language'] = 'en'  # shouldn't be preserved
            resp['ETag'] = '"spam"'
            resp.set_cookie('key', 'value')
            return resp

        self.req.META['HTTP_IF_NONE_MATCH'] = '"spam"'

        new_response = ConditionalGetMiddleware(get_response)(self.req)
        self.assertEqual(new_response.status_code, 304)
        base_response = get_response(self.req)
        for header in ('Cache-Control', 'Content-Location', 'Date', 'ETag', 'Expires', 'Last-Modified', 'Vary'):
            self.assertEqual(new_response.headers[header], base_response.headers[header])
        self.assertEqual(new_response.cookies, base_response.cookies)
        self.assertNotIn('Content-Language', new_response)

    def test_no_unsafe(self):
        """
        ConditionalGetMiddleware shouldn't return a conditional response on an
        unsafe request. A response has already been generated by the time
        ConditionalGetMiddleware is called, so it's too late to return a 412
        Precondition Failed.
        """
        def get_200_response(req):
            return HttpResponse(status=200)

        response = ConditionalGetMiddleware(self.get_response)(self.req)
        etag = response.headers['ETag']
        put_request = self.request_factory.put('/', HTTP_IF_MATCH=etag)
        conditional_get_response = ConditionalGetMiddleware(get_200_response)(put_request)
        self.assertEqual(conditional_get_response.status_code, 200)  # should never be a 412

    def test_no_head(self):
        """
        ConditionalGetMiddleware shouldn't compute and return an ETag on a
        HEAD request since it can't do so accurately without access to the
        response body of the corresponding GET.
        """
        def get_200_response(req):
            return HttpResponse(status=200)

        request = self.request_factory.head('/')
        conditional_get_response = ConditionalGetMiddleware(get_200_response)(request)
        self.assertNotIn('ETag', conditional_get_response)


class XFrameOptionsMiddlewareTest(SimpleTestCase):
    """
    Tests for the X-Frame-Options clickjacking prevention middleware.
    """

    def test_same_origin(self):
        """
        The X_FRAME_OPTIONS setting can be set to SAMEORIGIN to have the
        middleware use that value for the HTTP header.
        """
        with override_settings(X_FRAME_OPTIONS='SAMEORIGIN'):
            r = XFrameOptionsMiddleware(get_response_empty)(HttpRequest())
            self.assertEqual(r.headers['X-Frame-Options'], 'SAMEORIGIN')

        with override_settings(X_FRAME_OPTIONS='sameorigin'):
            r = XFrameOptionsMiddleware(get_response_empty)(HttpRequest())
            self.assertEqual(r.headers['X-Frame-Options'], 'SAMEORIGIN')

    def test_deny(self):
        """
        The X_FRAME_OPTIONS setting can be set to DENY to have the middleware
        use that value for the HTTP header.
        """
        with override_settings(X_FRAME_OPTIONS='DENY'):
            r = XFrameOptionsMiddleware(get_response_empty)(HttpRequest())
            self.assertEqual(r.headers['X-Frame-Options'], 'DENY')

        with override_settings(X_FRAME_OPTIONS='deny'):
            r = XFrameOptionsMiddleware(get_response_empty)(HttpRequest())
            self.assertEqual(r.headers['X-Frame-Options'], 'DENY')

    def test_defaults_sameorigin(self):
        """
        If the X_FRAME_OPTIONS setting is not set then it defaults to
        DENY.
        """
        with override_settings(X_FRAME_OPTIONS=None):
            del settings.X_FRAME_OPTIONS    # restored by override_settings
            r = XFrameOptionsMiddleware(get_response_empty)(HttpRequest())
            self.assertEqual(r.headers['X-Frame-Options'], 'DENY')

    def test_dont_set_if_set(self):
        """
        If the X-Frame-Options header is already set then the middleware does
        not attempt to override it.
        """
        def same_origin_response(request):
            response = HttpResponse()
            response.headers['X-Frame-Options'] = 'SAMEORIGIN'
            return response

        def deny_response(request):
            response = HttpResponse()
            response.headers['X-Frame-Options'] = 'DENY'
            return response

        with override_settings(X_FRAME_OPTIONS='DENY'):
            r = XFrameOptionsMiddleware(same_origin_response)(HttpRequest())
            self.assertEqual(r.headers['X-Frame-Options'], 'SAMEORIGIN')

        with override_settings(X_FRAME_OPTIONS='SAMEORIGIN'):
            r = XFrameOptionsMiddleware(deny_response)(HttpRequest())
            self.assertEqual(r.headers['X-Frame-Options'], 'DENY')

    def test_response_exempt(self):
        """
        If the response has an xframe_options_exempt attribute set to False
        then it still sets the header, but if it's set to True then it doesn't.
        """
        def xframe_exempt_response(request):
            response = HttpResponse()
            response.xframe_options_exempt = True
            return response

        def xframe_not_exempt_response(request):
            response = HttpResponse()
            response.xframe_options_exempt = False
            return response

        with override_settings(X_FRAME_OPTIONS='SAMEORIGIN'):
            r = XFrameOptionsMiddleware(xframe_not_exempt_response)(HttpRequest())
            self.assertEqual(r.headers['X-Frame-Options'], 'SAMEORIGIN')

            r = XFrameOptionsMiddleware(xframe_exempt_response)(HttpRequest())
            self.assertIsNone(r.headers.get('X-Frame-Options'))

    def test_is_extendable(self):
        """
        The XFrameOptionsMiddleware method that determines the X-Frame-Options
        header value can be overridden based on something in the request or
        response.
        """
        class OtherXFrameOptionsMiddleware(XFrameOptionsMiddleware):
            # This is just an example for testing purposes...
            def get_xframe_options_value(self, request, response):
                if getattr(request, 'sameorigin', False):
                    return 'SAMEORIGIN'
                if getattr(response, 'sameorigin', False):
                    return 'SAMEORIGIN'
                return 'DENY'

        def same_origin_response(request):
            response = HttpResponse()
            response.sameorigin = True
            return response

        with override_settings(X_FRAME_OPTIONS='DENY'):
            r = OtherXFrameOptionsMiddleware(same_origin_response)(HttpRequest())
            self.assertEqual(r.headers['X-Frame-Options'], 'SAMEORIGIN')

            request = HttpRequest()
            request.sameorigin = True
            r = OtherXFrameOptionsMiddleware(get_response_empty)(request)
            self.assertEqual(r.headers['X-Frame-Options'], 'SAMEORIGIN')

        with override_settings(X_FRAME_OPTIONS='SAMEORIGIN'):
            r = OtherXFrameOptionsMiddleware(get_response_empty)(HttpRequest())
            self.assertEqual(r.headers['X-Frame-Options'], 'DENY')


class GZipMiddlewareTest(SimpleTestCase):
    """
    Tests the GZipMiddleware.
    """
    short_string = b"This string is too short to be worth compressing."
    compressible_string = b'a' * 500
    incompressible_string = b''.join(int2byte(random.randint(0, 255)) for _ in range(500))
    sequence = [b'a' * 500, b'b' * 200, b'a' * 300]
    sequence_unicode = ['a' * 500, 'é' * 200, 'a' * 300]
    request_factory = RequestFactory()

    def setUp(self):
        self.req = self.request_factory.get('/')
        self.req.META['HTTP_ACCEPT_ENCODING'] = 'gzip, deflate'
        self.req.META['HTTP_USER_AGENT'] = 'Mozilla/5.0 (Windows NT 5.1; rv:9.0.1) Gecko/20100101 Firefox/9.0.1'
        self.resp = HttpResponse()
        self.resp.status_code = 200
        self.resp.content = self.compressible_string
        self.resp['Content-Type'] = 'text/html; charset=UTF-8'

    def get_response(self, request):
        return self.resp

    @staticmethod
    def decompress(gzipped_string):
        with gzip.GzipFile(mode='rb', fileobj=BytesIO(gzipped_string)) as f:
            return f.read()

    @staticmethod
    def get_mtime(gzipped_string):
        with gzip.GzipFile(mode='rb', fileobj=BytesIO(gzipped_string)) as f:
            f.read()  # must read the data before accessing the header
            return f.mtime

    def test_compress_response(self):
        """
        Compression is performed on responses with compressible content.
        """
        r = GZipMiddleware(self.get_response)(self.req)
        self.assertEqual(self.decompress(r.content), self.compressible_string)
        self.assertEqual(r.get('Content-Encoding'), 'gzip')
        self.assertEqual(r.get('Content-Length'), str(len(r.content)))

    def test_compress_streaming_response(self):
        """
        Compression is performed on responses with streaming content.
        """
        def get_stream_response(request):
            resp = StreamingHttpResponse(self.sequence)
            resp['Content-Type'] = 'text/html; charset=UTF-8'
            return resp

        r = GZipMiddleware(get_stream_response)(self.req)
        self.assertEqual(self.decompress(b''.join(r)), b''.join(self.sequence))
        self.assertEqual(r.get('Content-Encoding'), 'gzip')
        self.assertFalse(r.has_header('Content-Length'))

    def test_compress_streaming_response_unicode(self):
        """
        Compression is performed on responses with streaming Unicode content.
        """
        def get_stream_response_unicode(request):
            resp = StreamingHttpResponse(self.sequence_unicode)
            resp['Content-Type'] = 'text/html; charset=UTF-8'
            return resp

        r = GZipMiddleware(get_stream_response_unicode)(self.req)
        self.assertEqual(
            self.decompress(b''.join(r)),
            b''.join(x.encode() for x in self.sequence_unicode)
        )
        self.assertEqual(r.get('Content-Encoding'), 'gzip')
        self.assertFalse(r.has_header('Content-Length'))

    def test_compress_file_response(self):
        """
        Compression is performed on FileResponse.
        """
        with open(__file__, 'rb') as file1:
            def get_response(req):
                file_resp = FileResponse(file1)
                file_resp['Content-Type'] = 'text/html; charset=UTF-8'
                return file_resp

            r = GZipMiddleware(get_response)(self.req)
            with open(__file__, 'rb') as file2:
                self.assertEqual(self.decompress(b''.join(r)), file2.read())
            self.assertEqual(r.get('Content-Encoding'), 'gzip')
            self.assertIsNot(r.file_to_stream, file1)

    def test_compress_non_200_response(self):
        """
        Compression is performed on responses with a status other than 200
        (#10762).
        """
        self.resp.status_code = 404
        r = GZipMiddleware(self.get_response)(self.req)
        self.assertEqual(self.decompress(r.content), self.compressible_string)
        self.assertEqual(r.get('Content-Encoding'), 'gzip')

    def test_no_compress_short_response(self):
        """
        Compression isn't performed on responses with short content.
        """
        self.resp.content = self.short_string
        r = GZipMiddleware(self.get_response)(self.req)
        self.assertEqual(r.content, self.short_string)
        self.assertIsNone(r.get('Content-Encoding'))

    def test_no_compress_compressed_response(self):
        """
        Compression isn't performed on responses that are already compressed.
        """
        self.resp['Content-Encoding'] = 'deflate'
        r = GZipMiddleware(self.get_response)(self.req)
        self.assertEqual(r.content, self.compressible_string)
        self.assertEqual(r.get('Content-Encoding'), 'deflate')

    def test_no_compress_incompressible_response(self):
        """
        Compression isn't performed on responses with incompressible content.
        """
        self.resp.content = self.incompressible_string
        r = GZipMiddleware(self.get_response)(self.req)
        self.assertEqual(r.content, self.incompressible_string)
        self.assertIsNone(r.get('Content-Encoding'))

    def test_compress_deterministic(self):
        """
        Compression results are the same for the same content and don't
        include a modification time (since that would make the results
        of compression non-deterministic and prevent
        ConditionalGetMiddleware from recognizing conditional matches
        on gzipped content).
        """
        r1 = GZipMiddleware(self.get_response)(self.req)
        r2 = GZipMiddleware(self.get_response)(self.req)
        self.assertEqual(r1.content, r2.content)
        self.assertEqual(self.get_mtime(r1.content), 0)
        self.assertEqual(self.get_mtime(r2.content), 0)


class ETagGZipMiddlewareTest(SimpleTestCase):
    """
    ETags are handled properly by GZipMiddleware.
    """
    rf = RequestFactory()
    compressible_string = b'a' * 500

    def test_strong_etag_modified(self):
        """
        GZipMiddleware makes a strong ETag weak.
        """
        def get_response(req):
            response = HttpResponse(self.compressible_string)
            response.headers['ETag'] = '"eggs"'
            return response

        request = self.rf.get('/', HTTP_ACCEPT_ENCODING='gzip, deflate')
        gzip_response = GZipMiddleware(get_response)(request)
        self.assertEqual(gzip_response.headers['ETag'], 'W/"eggs"')

    def test_weak_etag_not_modified(self):
        """
        GZipMiddleware doesn't modify a weak ETag.
        """
        def get_response(req):
            response = HttpResponse(self.compressible_string)
            response.headers['ETag'] = 'W/"eggs"'
            return response

        request = self.rf.get('/', HTTP_ACCEPT_ENCODING='gzip, deflate')
        gzip_response = GZipMiddleware(get_response)(request)
        self.assertEqual(gzip_response.headers['ETag'], 'W/"eggs"')

    def test_etag_match(self):
        """
        GZipMiddleware allows 304 Not Modified responses.
        """
        def get_response(req):
            response = HttpResponse(self.compressible_string)
            return response

        def get_cond_response(req):
            return ConditionalGetMiddleware(get_response)(req)

        request = self.rf.get('/', HTTP_ACCEPT_ENCODING='gzip, deflate')
        response = GZipMiddleware(get_cond_response)(request)
        gzip_etag = response.headers['ETag']
        next_request = self.rf.get('/', HTTP_ACCEPT_ENCODING='gzip, deflate', HTTP_IF_NONE_MATCH=gzip_etag)
        next_response = ConditionalGetMiddleware(get_response)(next_request)
        self.assertEqual(next_response.status_code, 304)