234 lines
9.4 KiB
Python
234 lines
9.4 KiB
Python
"""passbook app_gw request handler"""
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import mimetypes
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from random import SystemRandom
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from urllib.parse import urlparse
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import certifi
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import urllib3
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from django.core.cache import cache
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from django.utils.http import urlencode
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from structlog import get_logger
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from passbook.app_gw.models import ApplicationGatewayProvider
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from passbook.app_gw.proxy.exceptions import InvalidUpstream
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from passbook.app_gw.proxy.response import get_django_response
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from passbook.app_gw.proxy.rewrite import Rewriter
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from passbook.app_gw.proxy.utils import encode_items, normalize_request_headers
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from passbook.core.models import Application
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from passbook.policy.engine import PolicyEngine
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SESSION_UPSTREAM_KEY = 'passbook_app_gw_upstream'
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IGNORED_HOSTNAMES_KEY = 'passbook_app_gw_ignored'
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LOGGER = get_logger(__name__)
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QUOTE_SAFE = r'<.;>\(}*+|~=-$/_:^@)[{]&\'!,"`'
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ERRORS_MESSAGES = {
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'upstream-no-scheme': ("Upstream URL scheme must be either "
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"'http' or 'https' (%s).")
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}
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HTTP_NO_VERIFY = urllib3.PoolManager()
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HTTP = urllib3.PoolManager(
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cert_reqs='CERT_REQUIRED',
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ca_certs=certifi.where())
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IGNORED_HOSTS = cache.get(IGNORED_HOSTNAMES_KEY, [])
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POLICY_CACHE = {}
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class RequestHandler:
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"""Forward requests"""
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_parsed_url = None
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_request_headers = None
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def __init__(self, app_gw, request):
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self.app_gw = app_gw
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self.request = request
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if self.app_gw.pk not in POLICY_CACHE:
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POLICY_CACHE[self.app_gw.pk] = self.app_gw.application.policies.all()
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@staticmethod
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def find_app_gw_for_request(request):
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"""Check if a request should be proxied or forwarded to passbook"""
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# Check if hostname is in cached list of ignored hostnames
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# This saves us having to query the database on each request
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host_header = request.META.get('HTTP_HOST')
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if host_header in IGNORED_HOSTS:
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# LOGGER.debug("%s is ignored", host_header)
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return False
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# Look through all ApplicationGatewayProviders and check hostnames
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matches = ApplicationGatewayProvider.objects.filter(
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server_name__contains=[host_header],
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enabled=True)
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if not matches.exists():
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# Mo matching Providers found, add host header to ignored list
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IGNORED_HOSTS.append(host_header)
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cache.set(IGNORED_HOSTNAMES_KEY, IGNORED_HOSTS)
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# LOGGER.debug("Ignoring %s", host_header)
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return False
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# At this point we're certain there's a matching ApplicationGateway
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if len(matches) > 1:
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# This should never happen
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raise ValueError
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app_gw = matches.first()
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try:
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# Check if ApplicationGateway is associated with application
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getattr(app_gw, 'application')
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if app_gw:
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return app_gw
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except Application.DoesNotExist:
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pass
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# LOGGER.debug("ApplicationGateway not associated with Application")
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return True
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def _get_upstream(self):
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"""Choose random upstream and save in session"""
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if SESSION_UPSTREAM_KEY not in self.request.session:
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self.request.session[SESSION_UPSTREAM_KEY] = {}
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if self.app_gw.pk not in self.request.session[SESSION_UPSTREAM_KEY]:
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upstream_index = int(SystemRandom().random() * len(self.app_gw.upstream))
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self.request.session[SESSION_UPSTREAM_KEY][self.app_gw.pk] = upstream_index
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return self.app_gw.upstream[self.request.session[SESSION_UPSTREAM_KEY][self.app_gw.pk]]
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def get_upstream(self):
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"""Get upstream as parsed url"""
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upstream = self._get_upstream()
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self._parsed_url = urlparse(upstream)
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if self._parsed_url.scheme not in ('http', 'https'):
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raise InvalidUpstream(ERRORS_MESSAGES['upstream-no-scheme'] %
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upstream)
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return upstream
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def _format_path_to_redirect(self):
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# LOGGER.debug("Path before: %s", self.request.get_full_path())
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rewriter = Rewriter(self.app_gw, self.request)
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after = rewriter.build()
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# LOGGER.debug("Path after: %s", after)
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return after
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def get_proxy_request_headers(self):
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"""Get normalized headers for the upstream
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Gets all headers from the original request and normalizes them.
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Normalization occurs by removing the prefix ``HTTP_`` and
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replacing and ``_`` by ``-``. Example: ``HTTP_ACCEPT_ENCODING``
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becames ``Accept-Encoding``.
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.. versionadded:: 0.9.1
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:param request: The original HTTPRequest instance
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:returns: Normalized headers for the upstream
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"""
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return normalize_request_headers(self.request)
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def get_request_headers(self):
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"""Return request headers that will be sent to upstream.
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The header REMOTE_USER is set to the current user
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if AuthenticationMiddleware is enabled and
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the view's add_remote_user property is True.
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.. versionadded:: 0.9.8
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"""
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request_headers = self.get_proxy_request_headers()
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if not self.app_gw.authentication_header:
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return request_headers
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request_headers[self.app_gw.authentication_header] = self.request.user.get_username()
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# LOGGER.debug("%s set", self.app_gw.authentication_header)
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return request_headers
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def check_permission(self):
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"""Check if user is authenticated and has permission to access app"""
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if not hasattr(self.request, 'user'):
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return False
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if not self.request.user.is_authenticated:
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return False
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policy_engine = PolicyEngine(POLICY_CACHE[self.app_gw.pk])
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policy_engine.for_user(self.request.user).with_request(self.request).build()
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passing, _messages = policy_engine.result
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return passing
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def get_encoded_query_params(self):
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"""Return encoded query params to be used in proxied request"""
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get_data = encode_items(self.request.GET.lists())
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return urlencode(get_data)
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def _created_proxy_response(self, path):
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request_payload = self.request.body
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# LOGGER.debug("Request headers: %s", self._request_headers)
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request_url = self.get_upstream() + path
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# LOGGER.debug("Request URL: %s", request_url)
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if self.request.GET:
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request_url += '?' + self.get_encoded_query_params()
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# LOGGER.debug("Request URL: %s", request_url)
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http = HTTP
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if not self.app_gw.upstream_ssl_verification:
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http = HTTP_NO_VERIFY
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try:
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proxy_response = http.urlopen(self.request.method,
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request_url,
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redirect=False,
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retries=None,
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headers=self._request_headers,
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body=request_payload,
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decode_content=False,
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preload_content=False)
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# LOGGER.debug("Proxy response header: %s",
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# proxy_response.getheaders())
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except urllib3.exceptions.HTTPError as error:
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LOGGER.exception(error)
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raise
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return proxy_response
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def _replace_host_on_redirect_location(self, proxy_response):
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location = proxy_response.headers.get('Location')
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if location:
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if self.request.is_secure():
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scheme = 'https://'
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else:
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scheme = 'http://'
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request_host = scheme + self.request.META.get('HTTP_HOST')
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upstream_host_http = 'http://' + self._parsed_url.netloc
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upstream_host_https = 'https://' + self._parsed_url.netloc
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location = location.replace(upstream_host_http, request_host)
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location = location.replace(upstream_host_https, request_host)
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proxy_response.headers['Location'] = location
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# LOGGER.debug("Proxy response LOCATION: %s",
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# proxy_response.headers['Location'])
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def _set_content_type(self, proxy_response):
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content_type = proxy_response.headers.get('Content-Type')
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if not content_type:
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content_type = (mimetypes.guess_type(self.request.path)[0] or
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self.app_gw.default_content_type)
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proxy_response.headers['Content-Type'] = content_type
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# LOGGER.debug("Proxy response CONTENT-TYPE: %s",
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# proxy_response.headers['Content-Type'])
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def get_response(self):
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"""Pass request to upstream and return response"""
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self._request_headers = self.get_request_headers()
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path = self._format_path_to_redirect()
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proxy_response = self._created_proxy_response(path)
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self._replace_host_on_redirect_location(proxy_response)
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self._set_content_type(proxy_response)
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response = get_django_response(proxy_response, strict_cookies=False)
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# If response has a 'Location' header, we rewrite that location as well
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if 'Location' in response:
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LOGGER.debug("Rewriting Location header")
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for server_name in self.app_gw.server_name:
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response['Location'] = response['Location'].replace(
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self._parsed_url.hostname, server_name)
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LOGGER.debug(response['Location'])
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# LOGGER.debug("RESPONSE RETURNED: %s", response)
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return response
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