summaryrefslogtreecommitdiff
path: root/src/leap/bitmask/backend/backend.py
blob: 26c547b63a1e6876703dcca0047ec3ab78eae3b8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
#!/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)