| """ |
| Functions that modify an HTTP request or response in some way. |
| """ |
| |
| # This group of functions are run as part of the response handling, after |
| # everything else, including all response middleware. Think of them as |
| # "compulsory response middleware". Be careful about what goes here, because |
| # it's a little fiddly to override this behavior, so they should be truly |
| # universally applicable. |
| |
| def fix_location_header(request, response): |
| """ |
| Ensures that we always use an absolute URI in any location header in the |
| response. This is required by RFC 2616, section 14.30. |
| |
| Code constructing response objects is free to insert relative paths, as |
| this function converts them to absolute paths. |
| """ |
| if 'Location' in response and request.get_host(): |
| response['Location'] = request.build_absolute_uri(response['Location']) |
| return response |
| |
| def conditional_content_removal(request, response): |
| """ |
| Removes the content of responses for HEAD requests, 1xx, 204 and 304 |
| responses. Ensures compliance with RFC 2616, section 4.3. |
| """ |
| if 100 <= response.status_code < 200 or response.status_code in (204, 304): |
| response.content = '' |
| response['Content-Length'] = 0 |
| if request.method == 'HEAD': |
| response.content = '' |
| return response |
| |
| def fix_IE_for_attach(request, response): |
| """ |
| This function will prevent Django from serving a Content-Disposition header |
| while expecting the browser to cache it (only when the browser is IE). This |
| leads to IE not allowing the client to download. |
| """ |
| if 'MSIE' not in request.META.get('HTTP_USER_AGENT', '').upper(): |
| return response |
| |
| offending_headers = ('no-cache', 'no-store') |
| if response.has_header('Content-Disposition'): |
| try: |
| del response['Pragma'] |
| except KeyError: |
| pass |
| if response.has_header('Cache-Control'): |
| cache_control_values = [value.strip() for value in |
| response['Cache-Control'].split(',') |
| if value.strip().lower() not in offending_headers] |
| |
| if not len(cache_control_values): |
| del response['Cache-Control'] |
| else: |
| response['Cache-Control'] = ', '.join(cache_control_values) |
| |
| return response |
| |
| def fix_IE_for_vary(request, response): |
| """ |
| This function will fix the bug reported at |
| http://support.microsoft.com/kb/824847/en-us?spid=8722&sid=global |
| by clearing the Vary header whenever the mime-type is not safe |
| enough for Internet Explorer to handle. Poor thing. |
| """ |
| if 'MSIE' not in request.META.get('HTTP_USER_AGENT', '').upper(): |
| return response |
| |
| # These mime-types that are decreed "Vary-safe" for IE: |
| safe_mime_types = ('text/html', 'text/plain', 'text/sgml') |
| |
| # The first part of the Content-Type field will be the MIME type, |
| # everything after ';', such as character-set, can be ignored. |
| if response['Content-Type'].split(';')[0] not in safe_mime_types: |
| try: |
| del response['Vary'] |
| except KeyError: |
| pass |
| |
| return response |
| |
