Add support for Vary header
diff --git a/python3/httplib2/__init__.py b/python3/httplib2/__init__.py
old mode 100755
new mode 100644
index d90a4a3..1cbcd4c
--- a/python3/httplib2/__init__.py
+++ b/python3/httplib2/__init__.py
@@ -337,6 +337,18 @@
                 if key not in ['status','content-encoding','transfer-encoding']:
                     info[key] = value
 
+            # Add annotations to the cache to indicate what headers
+            # are variant for this request.
+            vary = response_headers.get('vary', None)
+            if vary:
+                vary_headers = vary.lower().replace(' ', '').split(',')
+                for header in vary_headers:
+                    key = '-varied-%s' % header
+                    try:
+                        info[key] = request_headers[header]
+                    except KeyError:
+                        pass
+
             status = response_headers.status
             if status == 304:
                 status = 200
@@ -1023,6 +1035,18 @@
                 # RFC 2616 Section 13.10
                 self.cache.delete(cachekey)
 
+            # Check the vary header in the cache to see if this request
+            # matches what varies in the cache.
+            if method in ['GET', 'HEAD'] and 'vary' in info:
+                vary = info['vary']
+                vary_headers = vary.lower().replace(' ', '').split(',')
+                for header in vary_headers:
+                    key = '-varied-%s' % header
+                    value = info[key]
+                    if headers.get(header, '') != value:
+                            cached_value = None
+                            break
+
             if cached_value and method in ["GET", "HEAD"] and self.cache and 'range' not in headers:
                 if '-x-permanent-redirect-url' in info:
                     # Should cached permanent redirects be counted in our redirection count? For now, yes.
diff --git a/python3/httplib2test.py b/python3/httplib2test.py
index 78ec082..810e88a 100755
--- a/python3/httplib2test.py
+++ b/python3/httplib2test.py
@@ -571,6 +571,76 @@
         (response, content) = self.http.request(uri, "GET")

         self.assertEqual(response.status, 410)

 

+    def testVaryHeaderSimple(self):

+        """

+        RFC 2616 13.6

+        When the cache receives a subsequent request whose Request-URI

+        specifies one or more cache entries including a Vary header field,

+        the cache MUST NOT use such a cache entry to construct a response

+        to the new request unless all of the selecting request-headers

+        present in the new request match the corresponding stored

+        request-headers in the original request.

+        """

+        # test that the vary header is sent

+        uri = urllib.parse.urljoin(base, "vary/accept.asis")

+        (response, content) = self.http.request(uri, "GET", headers={'Accept': 'text/plain'})

+        self.assertEqual(response.status, 200)

+        self.assertTrue('vary' in response)

+

+        # get the resource again, from the cache since accept header in this

+        # request is the same as the request

+        (response, content) = self.http.request(uri, "GET", headers={'Accept': 'text/plain'})

+        self.assertEqual(response.status, 200)

+        self.assertEqual(response.fromcache, True, msg="Should be from cache")

+

+        # get the resource again, not from cache since Accept headers does not match

+        (response, content) = self.http.request(uri, "GET", headers={'Accept': 'text/html'})

+        self.assertEqual(response.status, 200)

+        self.assertEqual(response.fromcache, False, msg="Should not be from cache")

+

+        # get the resource again, without any Accept header, so again no match

+        (response, content) = self.http.request(uri, "GET")

+        self.assertEqual(response.status, 200)

+        self.assertEqual(response.fromcache, False, msg="Should not be from cache")

+

+    def testNoVary(self):

+        # when there is no vary, a different Accept header (e.g.) should not

+        # impact if the cache is used

+        # test that the vary header is not sent

+        uri = urllib.parse.urljoin(base, "vary/no-vary.asis")

+        (response, content) = self.http.request(uri, "GET", headers={'Accept': 'text/plain'})

+        self.assertEqual(response.status, 200)

+        self.assertFalse('vary' in response)

+

+        (response, content) = self.http.request(uri, "GET", headers={'Accept': 'text/plain'})

+        self.assertEqual(response.status, 200)

+        self.assertEqual(response.fromcache, True, msg="Should be from cache")

+        

+        (response, content) = self.http.request(uri, "GET", headers={'Accept': 'text/html'})

+        self.assertEqual(response.status, 200)

+        self.assertEqual(response.fromcache, True, msg="Should be from cache")

+

+    def testVaryHeaderDouble(self):

+        uri = urllib.parse.urljoin(base, "vary/accept-double.asis")

+        (response, content) = self.http.request(uri, "GET", headers={

+            'Accept': 'text/plain', 'Accept-Language': 'da, en-gb;q=0.8, en;q=0.7'})

+        self.assertEqual(response.status, 200)

+        self.assertTrue('vary' in response)

+

+        # we are from cache

+        (response, content) = self.http.request(uri, "GET", headers={

+            'Accept': 'text/plain', 'Accept-Language': 'da, en-gb;q=0.8, en;q=0.7'})

+        self.assertEqual(response.fromcache, True, msg="Should be from cache")

+

+        (response, content) = self.http.request(uri, "GET", headers={'Accept': 'text/plain'})

+        self.assertEqual(response.status, 200)

+        self.assertEqual(response.fromcache, False)

+

+        # get the resource again, not from cache, varied headers don't match exact

+        (response, content) = self.http.request(uri, "GET", headers={'Accept-Language': 'da'})

+        self.assertEqual(response.status, 200)

+        self.assertEqual(response.fromcache, False, msg="Should not be from cache")

+

     def testHeadGZip(self):

         # Test that we don't try to decompress a HEAD response 

         uri = urllib.parse.urljoin(base, "gzip/final-destination.txt")