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-rw-r--r--src/leap/bitmask/backend/backend_proxy.py142
1 files changed, 142 insertions, 0 deletions
diff --git a/src/leap/bitmask/backend/backend_proxy.py b/src/leap/bitmask/backend/backend_proxy.py
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+++ b/src/leap/bitmask/backend/backend_proxy.py
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+#!/usr/bin/env python
+# encoding: utf-8
+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.
+ response = self._socket.recv()
+ msg = "Received reply for '{0}' -> '{1}'".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)