Fix the race condition with novnc

The first RFP negotiation message potentially arrived
earlier, in which case the message will be swallowed
by the recv() which receive response for the http
request. This commit is to ensure only the response
is removed from the socket buffer, so it won't impact
the following RFP negotiation.

Change-Id: I100e140acbc2d981f7b98e12b3e9ae02844f41fd
Closes-Bug: #1695844

nova/console/websocketproxy.py

@@ -147,12 +147,15 @@ class NovaProxyRequestHandlerBase(object):
         if connect_info.get('internal_access_path'):
             tsock.send("CONNECT %s HTTP/1.1\r\n\r\n" %
                         connect_info['internal_access_path'])
+            end_token = "\r\n\r\n"
             while True:
                 data = tsock.recv(4096, socket.MSG_PEEK)
-                if data.find("\r\n\r\n") != -1:
+                token_loc = data.find(end_token)
+                if token_loc != -1:
                     if data.split("\r\n")[0].find("200") == -1:
                         raise exception.InvalidConnectionInfo()
-                    tsock.recv(len(data))
+                    # remove the response from recv buffer
+                    tsock.recv(token_loc + len(end_token))
                     break
 
         # Start proxying

nova/tests/unit/console/test_websocketproxy.py

@@ -17,6 +17,8 @@
 
 import mock
 
+import socket
+
 from nova.console import websocketproxy
 from nova import exception
 from nova import test
@@ -180,6 +182,35 @@ class NovaProxyRequestHandlerBaseTestCase(test.NoDBTestCase):
                           self.wh.new_websocket_client)
         check_token.assert_called_with(mock.ANY, token="123-456-789")
 
+    @mock.patch('nova.consoleauth.rpcapi.ConsoleAuthAPI.check_token')
+    def test_new_websocket_client_internal_access_path_rfb(self, check_token):
+        check_token.return_value = {
+            'host': 'node1',
+            'port': '10000',
+            'internal_access_path': 'vmid',
+            'console_type': 'novnc',
+            'access_url': 'https://example.net:6080'
+        }
+
+        tsock = mock.MagicMock()
+        HTTP_RESP = "HTTP/1.1 200 OK\r\n\r\n"
+        RFB_MSG = "RFB 003.003\n"
+        # RFB negotiation message may arrive earlier.
+        tsock.recv.side_effect = [HTTP_RESP + RFB_MSG,
+                                  HTTP_RESP]
+
+        self.wh.socket.return_value = tsock
+        self.wh.path = "http://127.0.0.1/?token=123-456-789"
+        self.wh.headers = self.fake_header
+
+        self.wh.new_websocket_client()
+
+        check_token.assert_called_with(mock.ANY, token="123-456-789")
+        self.wh.socket.assert_called_with('node1', 10000, connect=True)
+        tsock.recv.assert_has_calls([mock.call(4096, socket.MSG_PEEK),
+                                     mock.call(len(HTTP_RESP))])
+        self.wh.do_proxy.assert_called_with(tsock)
+
     @mock.patch.object(websocketproxy, 'sys')
     @mock.patch('nova.consoleauth.rpcapi.ConsoleAuthAPI.check_token')
     def test_new_websocket_client_py273_good_scheme(