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1 """ |
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2 Functions that modify an HTTP request or response in some way. |
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3 """ |
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4 |
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5 # This group of functions are run as part of the response handling, after |
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6 # everything else, including all response middleware. Think of them as |
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7 # "compulsory response middleware". Be careful about what goes here, because |
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8 # it's a little fiddly to override this behavior, so they should be truly |
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9 # universally applicable. |
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10 |
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11 def fix_location_header(request, response): |
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12 """ |
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13 Ensures that we always use an absolute URI in any location header in the |
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14 response. This is required by RFC 2616, section 14.30. |
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15 |
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16 Code constructing response objects is free to insert relative paths, as |
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17 this function converts them to absolute paths. |
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18 """ |
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19 if 'Location' in response and request.get_host(): |
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20 response['Location'] = request.build_absolute_uri(response['Location']) |
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21 return response |
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22 |
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23 def conditional_content_removal(request, response): |
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24 """ |
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25 Removes the content of responses for HEAD requests, 1xx, 204 and 304 |
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26 responses. Ensures compliance with RFC 2616, section 4.3. |
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27 """ |
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28 if 100 <= response.status_code < 200 or response.status_code in (204, 304): |
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29 response.content = '' |
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30 response['Content-Length'] = 0 |
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31 if request.method == 'HEAD': |
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32 response.content = '' |
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33 return response |
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34 |
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35 def fix_IE_for_attach(request, response): |
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36 """ |
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37 This function will prevent Django from serving a Content-Disposition header |
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38 while expecting the browser to cache it (only when the browser is IE). This |
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39 leads to IE not allowing the client to download. |
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40 """ |
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41 if 'MSIE' not in request.META.get('HTTP_USER_AGENT', '').upper(): |
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42 return response |
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43 |
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44 offending_headers = ('no-cache', 'no-store') |
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45 if response.has_header('Content-Disposition'): |
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46 try: |
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47 del response['Pragma'] |
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48 except KeyError: |
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49 pass |
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50 if response.has_header('Cache-Control'): |
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51 cache_control_values = [value.strip() for value in |
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52 response['Cache-Control'].split(',') |
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53 if value.strip().lower() not in offending_headers] |
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54 |
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55 if not len(cache_control_values): |
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56 del response['Cache-Control'] |
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57 else: |
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58 response['Cache-Control'] = ', '.join(cache_control_values) |
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59 |
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60 return response |
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61 |
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62 def fix_IE_for_vary(request, response): |
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63 """ |
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64 This function will fix the bug reported at |
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65 http://support.microsoft.com/kb/824847/en-us?spid=8722&sid=global |
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66 by clearing the Vary header whenever the mime-type is not safe |
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67 enough for Internet Explorer to handle. Poor thing. |
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68 """ |
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69 if 'MSIE' not in request.META.get('HTTP_USER_AGENT', '').upper(): |
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70 return response |
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71 |
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72 # These mime-types that are decreed "Vary-safe" for IE: |
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73 safe_mime_types = ('text/html', 'text/plain', 'text/sgml') |
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74 |
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75 # The first part of the Content-Type field will be the MIME type, |
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76 # everything after ';', such as character-set, can be ignored. |
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77 if response['Content-Type'].split(';')[0] not in safe_mime_types: |
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78 try: |
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79 del response['Vary'] |
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80 except KeyError: |
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81 pass |
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82 |
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83 return response |
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84 |