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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 logging
import tornado.websocket
from .utils import get_host_ip
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``.
"""
name = "fg21sim"
from_localhost = None
def open(self):
"""Invoked when a new WebSocket is opened by the client."""
logger.info("WebSocket: %s: opened" % self.name)
def on_message(self, message):
"""Handle incoming messages."""
logger.info("WebSocket: %s: received: %s" % (self.name, message))
msg_back = message[::-1]
logger.info("WebSocket: %s: sent: %s" % (self.name, msg_back))
self.write_message(msg_back)
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))
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.
"""
logger.info("WebSocket: {0}: origin: {1}".format(self.name, origin))
ip = get_host_ip(url=origin)
if ip == "127.0.0.1":
self.from_localhost = True
logger.info("WebSocket: %s: origin is localhost" % self.name)
return True
else:
self.from_localhost = False
# FIXME/TODO: check whether from local LAN (or in same subnet)??
logger.error("WebSocket: %s: " % self.name +
"ONLY allow access from localhost at the moment :(")
return False
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