Fix s3api cross policy copy

In s3api's request object we copy backend headers into the request
environ for logging after we call get_response.  The problem with s3api
copy is that we make a pre-flight HEAD request to the source object
using the same request object, so the first response backend headers
pollute the request and the proxy won't over-ride the backend header
with the correct storage policy.

As a possible fix we simply remove the problematic header from the
request object after the pre-flight HEAD request finishes.

Change-Id: I40b252446b3a1294a5ca8b531f224ce9c16f9aba

swift/common/middleware/s3api/s3request.py

@@ -916,6 +916,8 @@ class S3Request(swob.Request):
         src_resp = self.get_response(app, 'HEAD', src_bucket,
                                      swob.str_to_wsgi(src_obj),
                                      headers=headers, query=query)
+        # we can't let this HEAD req spoil our COPY
+        self.headers.pop('x-backend-storage-policy-index')
         if src_resp.status_int == 304:  # pylint: disable-msg=E1101
             raise PreconditionFailed()
 

test/unit/common/middleware/helpers.py

@@ -189,7 +189,8 @@ class FakeSwift(object):
 
         # simulate object GET/HEAD
         elif method in ('GET', 'HEAD') and obj:
-            req.headers['X-Backend-Storage-Policy-Index'] = '2'
+            req.headers['X-Backend-Storage-Policy-Index'] = headers.get(
+                'x-backend-storage-policy-index', '2')
 
         # note: tests may assume this copy of req_headers is case insensitive
         # so we deliberately use a HeaderKeyDict

test/unit/common/middleware/s3api/test_obj.py

@@ -835,6 +835,30 @@ class TestS3ApiObj(S3ApiTestCase):
                    return_value=timestamp):
             return self.call_s3api(req)
 
+    def test_simple_object_copy(self):
+        self.swift.register('HEAD', '/v1/AUTH_test/some/source',
+                            swob.HTTPOk, {
+                                'x-backend-storage-policy-index': '1',
+                            }, None)
+        req = Request.blank(
+            '/bucket/object', method='PUT',
+            headers={
+                'Authorization': 'AWS test:tester:hmac',
+                'X-Amz-Copy-Source': '/some/source',
+                'Date': self.get_date_header(),
+            },
+        )
+        timestamp = time.time()
+        with patch('swift.common.middleware.s3api.utils.time.time',
+                   return_value=timestamp):
+            status, headers, body = self.call_s3api(req)
+        self.assertEqual(status.split()[0], '200')
+        head_call, put_call = self.swift.calls_with_headers
+        self.assertEqual(
+            head_call.headers['x-backend-storage-policy-index'], '1')
+        self.assertEqual(put_call.headers['x-copy-from'], '/some/source')
+        self.assertNotIn('x-backend-storage-policy-index', put_call.headers)
+
     @s3acl
     def test_object_PUT_copy(self):
         def do_test(src_path):