1 from django.core.exceptions import MiddlewareNotUsed

     2 from django.utils.http import http_date

     3 

     4 class ConditionalGetMiddleware(object):

     5     """

     6     Handles conditional GET operations. If the response has a ETag or

     7     Last-Modified header, and the request has If-None-Match or

     8     If-Modified-Since, the response is replaced by an HttpNotModified.

     9 

    10     Also sets the Date and Content-Length response-headers.

    11     """

    12     def process_response(self, request, response):

    13         response['Date'] = http_date()

    14         if not response.has_header('Content-Length'):

    15             response['Content-Length'] = str(len(response.content))

    16 

    17         if response.has_header('ETag'):

    18             if_none_match = request.META.get('HTTP_IF_NONE_MATCH', None)

    19             if if_none_match == response['ETag']:

    20                 # Setting the status is enough here. The response handling path

    21                 # automatically removes content for this status code (in

    22                 # http.conditional_content_removal()).

    23                 response.status_code = 304

    24 

    25         if response.has_header('Last-Modified'):

    26             if_modified_since = request.META.get('HTTP_IF_MODIFIED_SINCE', None)

    27             if if_modified_since == response['Last-Modified']:

    28                 # Setting the status code is enough here (same reasons as

    29                 # above).

    30                 response.status_code = 304

    31 

    32         return response

    33 

    34 class SetRemoteAddrFromForwardedFor(object):

    35     """

    36     This middleware has been removed; see the Django 1.1 release notes for

    37     details.

    38     

    39     It previously set REMOTE_ADDR based on HTTP_X_FORWARDED_FOR. However, after

    40     investiagtion, it turns out this is impossible to do in a general manner:

    41     different proxies treat the X-Forwarded-For header differently. Thus, a

    42     built-in middleware can lead to application-level security problems, and so

    43     this was removed in Django 1.1

    44     

    45     """

    46     def __init__(self):

    47         import warnings

    48         warnings.warn("SetRemoteAddrFromForwardedFor has been removed. "

    49                       "See the Django 1.1 release notes for details.",

    50                       category=DeprecationWarning)

    51         raise MiddlewareNotUsed()