for endpoint with port == 0, read the port and hostname from the crea… (#239)

* for endpoint with port == 0, read the port and hostname from the created server scoket

this sets the port number from the created socket, possibly this change could trickle up to the actual server in the endpoint name

* fix copy paste error

opcua/server/binary_server_asyncio.py

@@ -95,6 +95,14 @@ class BinaryServer(object):
 
         coro = self.loop.create_server(OPCUAProtocol, self.hostname, self.port)
         self._server = self.loop.run_coro_and_wait(coro)
+        # get the port and the hostname from the created server socket
+        # only relevant for dynamic port asignment (when self.port == 0)
+        if self.port == 0 and len(self._server.sockets) == 1:
+            # will work for AF_INET and AF_INET6 socket names
+            # these are to only families supported by the create_server call
+            sockname = self._server.sockets[0].getsockname()
+            self.hostname = sockname[0]
+            self.port = sockname[1]
         print('Listening on {}:{}'.format(self.hostname, self.port))
 
     def stop(self):