Make proxy-logging more like eventlet.posthook

The old use of Eventlet's posthook process meant that responses that
forgot to include content-length or transfer-encoding headers would
get one tacked on, if Eventlet could guess what was probably meant. I
added a bit of that logic into proxy-logging now as we saw some
errors resulting from this.

Fixes Bug #1012714

Change-Id: I671453eaf3704eab814ff12c4625ba7d749cc7ed

swift/common/middleware/proxy_logging.py

@@ -167,6 +167,9 @@ def iter_response(iterable):
             else:
                 if not chunk:
                     start_response_args[0][1].append(('content-length', '0'))
+                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 '

test/unit/common/middleware/test_proxy_logging.py

@@ -34,6 +34,17 @@ def __call__(self, env, start_response):
         return self.body
 
 
+class FakeAppNoContentLengthNoTransferEncoding(object):
+    def __init__(self, body=['FAKE APP']):
+        self.body = body
+
+    def __call__(self, env, start_response):
+        start_response('200 OK', [('Content-Type', 'text/plain')])
+        while env['wsgi.input'].read(5):
+            pass
+        return self.body
+
+
 class FileLikeExceptor(object):
     def __init__(self):
         pass
@@ -226,5 +237,14 @@ def test_disconnect_on_read(self):
         self.assertEquals(log_parts[6], '499')
         self.assertEquals(log_parts[10], '-')  # read length
 
+    def test_no_content_length_no_transfer_encoding(self):
+        app = proxy_logging.ProxyLoggingMiddleware(
+                FakeAppNoContentLengthNoTransferEncoding(), {})
+        app.access_logger = FakeLogger()
+        req = Request.blank('/', environ={'REQUEST_METHOD': 'GET'})
+        resp = app(req.environ, start_response)
+        body = ''.join(resp)
+
+
 if __name__ == '__main__':
     unittest.main()