Fixed #10681 -- Work around (by ignoring) invalid ETag headers.

This is a hack to work around problems in the Real World. Apparently, Opera
9.64 has been observed sending malformed headers. We now compromise our high
principles and simply ignore such bad behaviour.

Patch from Ivan Sagalaev.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@10370 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/views/decorators/http.py

@@ -75,7 +75,15 @@ def condition(etag_func=None, last_modified_func=None):
             if if_none_match or if_match:
                 # There can be more than one ETag in the request, so we
                 # consider the list of values.
-                etags = parse_etags(if_none_match or if_match)
+                try:
+                    etags = parse_etags(if_none_match or if_match)
+                except ValueError:
+                    # In case of invalid etag ignore all ETag headers.
+                    # Apparently Opera sends invalidly quoted headers at times
+                    # (we should be returning a 400 response, but that's a
+                    # little extreme) -- this is Django bug #10681.
+                    if_none_match = None
+                    if_match = None
 
             # Compute values (if any) for the requested resource.
             if etag_func:

tests/regressiontests/conditional_processing/models.py

@@ -112,6 +112,11 @@ class ConditionalGet(TestCase):
         response = self.client.get('/condition/last_modified2/')
         self.assertFullResponse(response, check_etag=False)
 
+    def testInvalidETag(self):
+        self.client.defaults['HTTP_IF_NONE_MATCH'] = r'"\"'
+        response = self.client.get('/condition/etag/')
+        self.assertFullResponse(response, check_last_modified=False)
+
 
 class ETagProcesing(TestCase):
     def testParsing(self):