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# Copyright (c) 2016 Weitian LI <liweitianux@live.com>
# 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
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