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Diffstat (limited to 'src/leap/bitmask/backend/backend_proxy.py')
| -rw-r--r-- | src/leap/bitmask/backend/backend_proxy.py | 162 |
1 files changed, 162 insertions, 0 deletions
diff --git a/src/leap/bitmask/backend/backend_proxy.py b/src/leap/bitmask/backend/backend_proxy.py new file mode 100644 index 00000000..f683e465 --- /dev/null +++ b/src/leap/bitmask/backend/backend_proxy.py @@ -0,0 +1,162 @@ +# -*- coding: utf-8 -*- +# backend_proxy.py +# Copyright (C) 2013, 2014 LEAP +# +# This program is free software: you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation, either version 3 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see <http://www.gnu.org/licenses/>. +""" +The BackendProxy handles calls from the GUI and forwards (through ZMQ) +to the backend. +""" +import functools +import Queue +import threading +import time + +import zmq + +from leap.bitmask.backend.api import API, STOP_REQUEST +from leap.bitmask.backend.utils import get_backend_certificates + +import logging +logger = logging.getLogger(__name__) + + +class BackendProxy(object): + """ + The BackendProxy handles calls from the GUI and forwards (through ZMQ) + to the backend. + """ + PORT = '5556' + SERVER = "tcp://localhost:%s" % PORT + + def __init__(self): + self._socket = None + + # initialize ZMQ stuff: + context = zmq.Context() + logger.debug("Connecting to server...") + socket = context.socket(zmq.REQ) + + # public, secret = zmq.curve_keypair() + client_keys = zmq.curve_keypair() + socket.curve_publickey = client_keys[0] + socket.curve_secretkey = client_keys[1] + + # The client must know the server's public key to make a CURVE + # connection. + public, _ = get_backend_certificates() + socket.curve_serverkey = public + + socket.setsockopt(zmq.RCVTIMEO, 1000) + socket.connect(self.SERVER) + self._socket = socket + + self._call_queue = Queue.Queue() + self._worker_caller = threading.Thread(target=self._worker) + self._worker_caller.start() + + def _worker(self): + """ + Worker loop that processes the Queue of pending requests to do. + """ + while True: + try: + request = self._call_queue.get(block=False) + # break the loop after sending the 'stop' action to the + # backend. + if request == STOP_REQUEST: + break + + self._send_request(request) + except Queue.Empty: + pass + time.sleep(0.01) + + logger.debug("BackendProxy worker stopped.") + + def _api_call(self, *args, **kwargs): + """ + Call the `api_method` method in backend (through zmq). + + :param kwargs: named arguments to forward to the backend api method. + :type kwargs: dict + + Note: is mandatory to have the kwarg 'api_method' defined. + """ + if args: + # Use a custom message to be more clear about using kwargs *only* + raise Exception("All arguments need to be kwargs!") + + api_method = kwargs.pop('api_method', None) + if api_method is None: + raise Exception("Missing argument, no method name specified.") + + request = { + 'api_method': api_method, + 'arguments': kwargs, + } + + try: + request_json = zmq.utils.jsonapi.dumps(request) + except Exception as e: + msg = ("Error serializing request into JSON.\n" + "Exception: {0} Data: {1}") + msg = msg.format(e, request) + logger.critical(msg) + raise + + # queue the call in order to handle the request in a thread safe way. + self._call_queue.put(request_json) + + if api_method == STOP_REQUEST: + self._call_queue.put(STOP_REQUEST) + + def _send_request(self, request): + """ + Send the given request to the server. + This is used from a thread safe loop in order to avoid sending a + request without receiving a response from a previous one. + + :param request: the request to send. + :type request: str + """ + # logger.debug("Sending request to backend: {0}".format(request)) + self._socket.send(request) + + try: + # Get the reply. + self._socket.recv() + # response = self._socket.recv() + # msg = "Received reply for '{0}' -> '{1}'" + # msg = msg.format(request, response) + # logger.debug(msg) + except zmq.error.Again as e: + msg = "Timeout error contacting backend. {0!r}".format(e) + logger.critical(msg) + + def __getattribute__(self, name): + """ + This allows the user to do: + bp = BackendProxy() + bp.some_method() + + Just by having defined 'some_method' in the API + + :param name: the attribute name that is requested. + :type name: str + """ + if name in API: + return functools.partial(self._api_call, api_method=name) + else: + return object.__getattribute__(self, name) |