# Copyright (c) 2016 Weitian LI # MIT license """ Communicate with the "fg21sim" simulation program through the Web UI using the WebSocket_ protocol, which provides full-duplex communication channels over a single TCP connection. .. _WebSocket: https://en.wikipedia.org/wiki/WebSocket References ---------- - Tornado WebSocket: http://www.tornadoweb.org/en/stable/websocket.html - Can I Use: WebSocket: http://caniuse.com/#feat=websockets """ import json import logging import tornado.websocket from tornado.options import options from .console import ConsoleHandler from .configs import ConfigsHandler from ..utils import get_host_ip, ip_in_network logger = logging.getLogger(__name__) class FG21simWSHandler(tornado.websocket.WebSocketHandler): """ WebSocket for bi-directional communication between the Web UI and the server, which can deal with the configurations and execute the simulation task. Generally, WebSocket send and receive data as *string*. Therefore, the more complex data are stringified as JSON string before sending, which will be parsed after receive. Each message (as a JSON object or Python dictionary) has a ``type`` field which will be used to determine the following action to take. Attributes ---------- name : str Name to distinguish this WebSocket handle. from_localhost : bool Set to ``True`` if the access is from the localhost, otherwise ``False``. configs : `~ConfigManager` A ``ConfigManager`` instance, for configuration manipulations when communicating with the Web UI. """ name = "fg21sim" from_localhost = None def check_origin(self, origin): """Check the origin of the WebSocket access. Attributes ---------- from_localhost : bool Set to ``True`` if the access is from the localhost, otherwise ``False``. NOTE ---- Currently, only allow access from the ``localhost`` (i.e., 127.0.0.1) and local LAN. """ self.from_localhost = False logger.info("WebSocket: {0}: origin: {1}".format(self.name, origin)) ip = get_host_ip(url=origin) network = options.hosts_allowed if ip == "127.0.0.1": self.from_localhost = True allow = True logger.info("WebSocket: %s: origin is localhost" % self.name) elif network.upper() == "ANY": # Any hosts are allowed allow = True logger.warning("WebSocket: %s: any hosts are allowed" % self.name) elif ip_in_network(ip, network): allow = True logger.info("WebSocket: %s: " % self.name + "client is in the allowed network: %s" % network) else: allow = False logger.error("WebSocket: %s: " % self.name + "client is NOT in the allowed network: %s" % network) return allow def open(self): """Invoked when a new WebSocket is opened by the client.""" # FIXME: # * better to move to the `Application` class ?? # * or create a ``ConfigsHandler`` similar to the ``ConsoleHandler`` self.configs = self.application.configmanager self.console_handler = ConsoleHandler(websocket=self) self.configs_handler = ConfigsHandler(configs=self.configs) # logger.info("WebSocket: {0}: opened".format(self.name)) logger.info("Allowed hosts: {0}".format(options.hosts_allowed)) def on_close(self): """Invoked when a new WebSocket is closed by the client.""" code, reason = None, None if hasattr(self, "close_code"): code = self.close_code if hasattr(self, "close_reason"): reason = self.close_reason logger.info("WebSocket: {0}: closed by client: {1}, {2}".format( self.name, code, reason)) # FIXME/XXX: # * How to be non-blocking ?? # NOTE: WebSocket.on_message: may NOT be a coroutine at the moment (v4.3) # References: # [1] https://stackoverflow.com/a/35543856/4856091 # [2] https://stackoverflow.com/a/33724486/4856091 def on_message(self, message): """Handle incoming messages and dispatch task according to the message type. NOTE ---- The received message (parsed to a Python dictionary) has a ``type`` item which will be used to determine the following action to take. Currently supported message types are: ``configs``: Request or set the configurations ``console``: Control the simulation tasks, or request logging messages ``results``: Request the simulation results The sent message also has a ``type`` item of same value, which the client can be used to figure out the proper actions. There is a ``success`` item which indicates the status of the requested operation, and an ``error`` recording the error message if ``success=False``. """ logger.debug("WebSocket: %s: received: %s" % (self.name, message)) try: msg = json.loads(message) msg_type = msg["type"] except json.JSONDecodeError: logger.warning("WebSocket: {0}: ".format(self.name) + "message is not a valid JSON string") response = {"success": False, "type": None, "error": "message is not a valid JSON string"} except (KeyError, TypeError): logger.warning("WebSocket: %s: skip invalid message" % self.name) response = {"success": False, "type": None, "error": "type is missing"} else: # Check the message type and dispatch task if msg_type == "configs": # Request or set the configurations response = self.configs_handler.handle_message(msg) elif msg_type == "console": # Control the simulation tasks, or request logging messages # FIXME/XXX: # * How to make this asynchronously ?? response = self.console_handler.handle_message(msg) elif msg_type == "results": # Request the simulation results response = self._handle_results(msg) else: # Message of unknown type logger.warning("WebSocket: {0}: ".format(self.name) + "unknown message type: {0}".format(msg_type)) response = {"success": False, "type": msg_type, "error": "unknown message type %s" % msg_type} # msg_response = json.dumps(response) self.write_message(msg_response) def _handle_results(self, msg): # Got a message of supported types msg_type = msg["type"] logger.info("WebSocket: {0}: ".format(self.name) + "handle message of type: {0}".format(msg_type)) response = {"success": True, "type": msg_type} return response