Fix 500 on GET of many-segment manifest.

The proxy_logging middleware was asserting that the response contained
either a Content-Length header or a Transfer-Encoding header. If not,
it would either add one (if app_iter was a list) or blow up
(otherwise). This blowing up is observable on a GET request to a
manifest object that references more than
swift.common.constraints.CONTAINER_LISTING_LIMIT segments.

If a response makes it up to eventlet.wsgi without a Content-Length
header, then a "Transfer-Encoding: chunked" header is automatically
stuffed into the response by eventlet. Therefore, it's not an error
for a response to not have a Content-Length header, and proxy_logging
should just let it happen.

Fixes bug 1078113.

Change-Id: I3751a8ae14dc68bab546f2746b61267a5115e252

swift/common/middleware/proxy_logging.py

@@ -205,10 +205,6 @@ class ProxyLoggingMiddleware(object):
                 elif isinstance(iterable, list):
                     start_response_args[0][1].append(
                         ('content-length', str(sum(len(i) for i in iterable))))
-                else:
-                    raise Exception('WSGI [proxy-logging]: No content-length '
-                                    'or transfer-encoding header sent and '
-                                    'there is content! %r' % chunk)
             start_response(*start_response_args[0])
             bytes_sent = 0
             client_disconnect = False

test/unit/common/middleware/test_proxy_logging.py

@@ -391,25 +391,6 @@ class TestProxyLogging(unittest.TestCase):
         self.assertEquals(resp_body, '')
         self.assertEquals(log_parts[11], '-')
 
-    def test_no_content_length_no_transfer_encoding_with_str_body(self):
-        app = proxy_logging.ProxyLoggingMiddleware(
-            FakeAppNoContentLengthNoTransferEncoding(
-                body='line1\nline2\n',
-            ), {})
-        app.access_logger = FakeLogger()
-        req = Request.blank('/', environ={'REQUEST_METHOD': 'GET'})
-        resp = app(req.environ, start_response)
-        # Python 2.7 can have assertRaises act as a context manager, but python
-        # 2.6 can't.  So there's this.
-        try:
-            resp_body = ''.join(resp)
-        except Exception as e:
-            self.assertEquals(
-                "WSGI [proxy-logging]: No content-length or transfer-encoding "
-                "header sent and there is content! 'l'", str(e))
-        else:
-            self.assert_(False)
-
     def test_req_path_info_popping(self):
         app = proxy_logging.ProxyLoggingMiddleware(FakeApp(), {})
         app.access_logger = FakeLogger()