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authorIvan Alejandro <ivanalejandro0@gmail.com>2014-07-08 16:45:43 -0300
committerIvan Alejandro <ivanalejandro0@gmail.com>2014-07-14 12:11:50 -0300
commit1eae3af1906f95d9d2d76c205b61799d248f0e71 (patch)
tree9fc8f3d0a6b01963068878582e9520933544023a /src/leap/bitmask/backend/backend.py
parent3795dedd26fc239e143ca2a29b7e16d433f964ba (diff)
Add base communication framework.
Diffstat (limited to 'src/leap/bitmask/backend/backend.py')
-rw-r--r--src/leap/bitmask/backend/backend.py196
1 files changed, 196 insertions, 0 deletions
diff --git a/src/leap/bitmask/backend/backend.py b/src/leap/bitmask/backend/backend.py
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+++ b/src/leap/bitmask/backend/backend.py
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+#!/usr/bin/env python
+# encoding: utf-8
+import json
+import threading
+import time
+
+from twisted.internet import defer, reactor, threads
+
+import zmq
+from zmq.auth.thread import ThreadAuthenticator
+
+from leap.bitmask.backend.api import API
+from leap.bitmask.backend.utils import get_backend_certificates
+from leap.bitmask.backend.signaler import Signaler
+
+import logging
+logger = logging.getLogger(__name__)
+
+
+class Backend(object):
+ """
+ Backend server.
+ Receives signals from backend_proxy and emit signals if needed.
+ """
+ PORT = '5556'
+ BIND_ADDR = "tcp://127.0.0.1:%s" % PORT
+
+ def __init__(self):
+ """
+ Backend constructor, create needed instances.
+ """
+ self._signaler = Signaler()
+
+ self._do_work = threading.Event() # used to stop the worker thread.
+ self._zmq_socket = None
+
+ self._ongoing_defers = []
+ self._init_zmq()
+
+ def _init_zmq(self):
+ """
+ Configure the zmq components and connection.
+ """
+ context = zmq.Context()
+ socket = context.socket(zmq.REP)
+
+ # Start an authenticator for this context.
+ auth = ThreadAuthenticator(context)
+ auth.start()
+ auth.allow('127.0.0.1')
+
+ # Tell authenticator to use the certificate in a directory
+ auth.configure_curve(domain='*', location=zmq.auth.CURVE_ALLOW_ANY)
+ public, secret = get_backend_certificates()
+ socket.curve_publickey = public
+ socket.curve_secretkey = secret
+ socket.curve_server = True # must come before bind
+
+ socket.bind(self.BIND_ADDR)
+
+ self._zmq_socket = socket
+
+ def _worker(self):
+ """
+ Receive requests and send it to process.
+
+ Note: we use a simple while since is less resource consuming than a
+ Twisted's LoopingCall.
+ """
+ while self._do_work.is_set():
+ # Wait for next request from client
+ try:
+ request = self._zmq_socket.recv(zmq.NOBLOCK)
+ self._zmq_socket.send("OK")
+ logger.debug("Received request: '{0}'".format(request))
+ self._process_request(request)
+ except zmq.ZMQError as e:
+ if e.errno != zmq.EAGAIN:
+ raise
+ time.sleep(0.01)
+
+ def _stop_reactor(self):
+ """
+ Stop the Twisted reactor, but first wait a little for some threads to
+ complete their work.
+
+ Note: this method needs to be run in a different thread so the
+ time.sleep() does not block and other threads can finish.
+ i.e.:
+ use threads.deferToThread(this_method) instead of this_method()
+ """
+ wait_max = 5 # seconds
+ wait_step = 0.5
+ wait = 0
+ while self._ongoing_defers and wait < wait_max:
+ time.sleep(wait_step)
+ wait += wait_step
+ msg = "Waiting for running threads to finish... {0}/{1}"
+ msg = msg.format(wait, wait_max)
+ logger.debug(msg)
+
+ # after a timeout we shut down the existing threads.
+ for d in self._ongoing_defers:
+ d.cancel()
+
+ reactor.stop()
+ logger.debug("Twisted reactor stopped.")
+
+ def run(self):
+ """
+ Start the ZMQ server and run the loop to handle requests.
+ """
+ self._signaler.start()
+ self._do_work.set()
+ threads.deferToThread(self._worker)
+ reactor.run()
+
+ def stop(self):
+ """
+ Stop the server and the zmq request parse loop.
+ """
+ logger.debug("STOP received.")
+ self._signaler.stop()
+ self._do_work.clear()
+ threads.deferToThread(self._stop_reactor)
+
+ def _process_request(self, request_json):
+ """
+ Process a request and call the according method with the given
+ parameters.
+
+ :param request_json: a json specification of a request.
+ :type request_json: str
+ """
+ try:
+ # request = zmq.utils.jsonapi.loads(request_json)
+ # We use stdlib's json to ensure that we get unicode strings
+ request = json.loads(request_json)
+ api_method = request['api_method']
+ kwargs = request['arguments'] or None
+ except Exception as e:
+ msg = "Malformed JSON data in Backend request '{0}'. Exc: {1!r}"
+ msg = msg.format(request_json, e)
+ msg = msg.format(request_json)
+ logger.critical(msg)
+ raise
+
+ if api_method not in API:
+ logger.error("Invalid API call '{0}'".format(api_method))
+ return
+
+ self._run_in_thread(api_method, kwargs)
+
+ def _run_in_thread(self, api_method, kwargs):
+ """
+ Run the method name in a thread with the given arguments.
+
+ :param api_method: the callable name to run in a thread.
+ :type api_method: str
+ :param kwargs: the arguments dict that will be sent to the callable.
+ :type kwargs: tuple
+ """
+ func = getattr(self, api_method)
+
+ method = func
+ if kwargs is not None:
+ method = lambda: func(**kwargs)
+
+ logger.debug("Running method: '{0}' "
+ "with args: '{1}' in a thread".format(api_method, kwargs))
+
+ # run the action in a thread and keep track of it
+ d = threads.deferToThread(method)
+ d.addCallback(self._done_action, d)
+ d.addErrback(self._done_action, d)
+ self._ongoing_defers.append(d)
+
+ def _done_action(self, failure, d):
+ """
+ Remove the defer from the ongoing list.
+
+ :param failure: the failure that triggered the errback.
+ None if no error.
+ :type failure: twisted.python.failure.Failure
+ :param d: defer to remove
+ :type d: twisted.internet.defer.Deferred
+ """
+ if failure is not None:
+ if failure.check(defer.CancelledError):
+ logger.debug("A defer was cancelled.")
+ else:
+ logger.error("There was a failure - {0!r}".format(failure))
+ logger.error(failure.getTraceback())
+
+ if d in self._ongoing_defers:
+ self._ongoing_defers.remove(d)