fix(console): novncd waits at most 5 s for a VNC server to answer

websockify's socket() connects without a timeout, so a console address
that does not answer held the console's process for the OS's TCP timeout
(some 2 minutes) before the page heard of it. novncd now connects with
CONNECT_TIMEOUT, then waits on the open connection as before.

console/novncd

@@ -25,7 +25,7 @@ from websockify import ProxyRequestHandler, WebSocketProxy  # noqa: E402
 from console.sshtunnels import open_tunnel, tunnel_target  # noqa: E402
 from console.tokens import ACCESS_CHECK, authorize, may_still_open, session_user_id  # noqa: E402
 from logs.audit import write  # noqa: E402
-from vrtManager.connection import CONN_SOCKET, CONN_SSH  # noqa: E402
+from vrtManager.connection import CONN_SOCKET, CONN_SSH, CONNECT_TIMEOUT  # noqa: E402
 from vrtManager.util import is_loopback  # noqa: E402
 from webvirtcloud.settings import WS_HOST, WS_PORT  # noqa: E402
 
@@ -79,6 +79,14 @@ def get_connection_infos(instance):
 WILDCARD = (None, "", "0.0.0.0", "::")
 
 
+def bounded_connect(host, port, connect=True):
+    """A connection to a VNC server, in place of websockify's socket(), which
+    waits for one that does not answer as long as the OS does (some 2 minutes)."""
+    tsock = socket.create_connection((host, port), timeout=CONNECT_TIMEOUT)
+    tsock.settimeout(None)  # a console may stay quiet for long once connected
+    return tsock
+
+
 def client_address(value):
     """The client's address nginx sends in X-Real-IP, or None."""
     try:
@@ -178,7 +186,7 @@ class ConsoleProxyHandler(ProxyRequestHandler, ConsoleClient):
         self.log_message(*args, **kwargs)
 
     def new_websocket_client(self):
-        self._new_client(self.server.socket)
+        self._new_client(bounded_connect)
 
 
 if __name__ == "__main__":

console/tests/test_views.py

@@ -570,6 +570,12 @@ class NovncdDaemonLogicTestCase(TestCase):
         # the VM access was checked for, not whichever VM has its name now
         self.assertEqual(mock_wvm.call_args.kwargs["uuid"], mock_instance.uuid)
 
+    def test_the_vnc_server_is_waited_for_a_bounded_time(self):
+        with patch.object(novncd_mod.socket, "create_connection") as create_connection:
+            tsock = novncd_mod.bounded_connect("192.0.2.40", 5900, connect=True)
+        create_connection.assert_called_once_with(("192.0.2.40", 5900), timeout=novncd_mod.CONNECT_TIMEOUT)
+        tsock.settimeout.assert_called_once_with(None)
+
     def test_a_token_without_its_users_session_is_refused_and_logged(self):
         from logs.models import Logs