summaryrefslogtreecommitdiff
path: root/slixmpp/plugins/xep_0009/remote.py
blob: b7612c03bfb88d69d9c8a2849b8b3489cb63aeeb (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
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
"""
    Slixmpp: The Slick XMPP Library
    Copyright (C) 2011 Nathanael C. Fritz, Dann Martens (TOMOTON).
    This file is part of Slixmpp.

    See the file LICENSE for copying permission.
"""

from binding import py2xml, xml2py, xml2fault, fault2xml
from threading import RLock
import abc
import inspect
import logging
import slixmpp
import sys
import threading
import traceback

log = logging.getLogger(__name__)

def _intercept(method, name, public):
    def _resolver(instance, *args, **kwargs):
        log.debug("Locally calling %s.%s with arguments %s.", instance.FQN(), method.__name__, args)
        try:
            value = method(instance, *args, **kwargs)
            if value == NotImplemented:
                raise InvocationException("Local handler does not implement %s.%s!" % (instance.FQN(), method.__name__))
            return value
        except InvocationException:
            raise
        except Exception as e:
            raise InvocationException("A problem occured calling %s.%s!" % (instance.FQN(), method.__name__), e)
    _resolver._rpc = public
    _resolver._rpc_name = method.__name__ if name is None else name
    return _resolver

def remote(function_argument, public = True):
    '''
    Decorator for methods which are remotely callable. This decorator
    works in conjunction with classes which extend ABC Endpoint.
    Example:

        @remote
        def remote_method(arg1, arg2)

    Arguments:
        function_argument -- a stand-in for either the actual method
            OR a new name (string) for the method. In that case the
            method is considered mapped:
            Example:

            @remote("new_name")
            def remote_method(arg1, arg2)

        public -- A flag which indicates if this method should be part
            of the known dictionary of remote methods. Defaults to True.
            Example:

            @remote(False)
            def remote_method(arg1, arg2)

    Note: renaming and revising (public vs. private) can be combined.
    Example:

            @remote("new_name", False)
            def remote_method(arg1, arg2)
    '''
    if hasattr(function_argument, '__call__'):
        return _intercept(function_argument, None, public)
    else:
        if not isinstance(function_argument, basestring):
            if not isinstance(function_argument, bool):
                raise Exception('Expected an RPC method name or visibility modifier!')
            else:
                def _wrap_revised(function):
                    function = _intercept(function, None, function_argument)
                    return function
                return _wrap_revised
        def _wrap_remapped(function):
            function = _intercept(function, function_argument, public)
            return function
        return _wrap_remapped


class ACL:
    '''
    An Access Control List (ACL) is a list of rules, which are evaluated
    in order until a match is found. The policy of the matching rule
    is then applied.

    Rules are 3-tuples, consisting of a policy enumerated type, a JID
    expression and a RCP resource expression.

    Examples:
    [ (ACL.ALLOW, '*', '*') ] allow everyone everything, no restrictions
    [ (ACL.DENY, '*', '*') ] deny everyone everything, no restrictions
    [ (ACL.ALLOW, 'test@xmpp.org/unit', 'test.*'),
      (ACL.DENY, '*', '*') ] deny everyone everything, except named
        JID, which is allowed access to endpoint 'test' only.

    The use of wildcards is allowed in expressions, as follows:
    '*' everyone, or everything (= all endpoints and methods)
    'test@xmpp.org/*' every JID regardless of JID resource
    '*@xmpp.org/rpc' every JID from domain xmpp.org with JID res 'rpc'
    'frank@*' every 'frank', regardless of domain or JID res
    'system.*' all methods of endpoint 'system'
    '*.reboot' all methods reboot regardless of endpoint
    '''
    ALLOW = True
    DENY = False

    @classmethod
    def check(cls, rules, jid, resource):
        if rules is None:
            return cls.DENY                  # No rules means no access!
        jid = str(jid)     # Check the string representation of the JID.
        if not jid:
            return cls.DENY                  # Can't check an empty JID.
        for rule in rules:
            policy = cls._check(rule, jid, resource)
            if policy is not None:
                return policy
        return cls.DENY   # By default if not rule matches, deny access.

    @classmethod
    def _check(cls, rule, jid, resource):
        if cls._match(jid, rule[1]) and cls._match(resource, rule[2]):
            return rule[0]
        else:
            return None

    @classmethod
    def _next_token(cls, expression, index):
        new_index = expression.find('*', index)
        if new_index == 0:
            return ''
        else:
            if new_index == -1:
                return expression[index : ]
            else:
                return expression[index : new_index]

    @classmethod
    def _match(cls, value, expression):
        #! print "_match [VALUE] %s [EXPR] %s" % (value, expression)
        index = 0
        position = 0
        while index < len(expression):
            token = cls._next_token(expression, index)
            #! print "[TOKEN] '%s'" % token
            size = len(token)
            if size > 0:
                token_index = value.find(token, position)
                if token_index == -1:
                    return False
                else:
                    #! print "[INDEX-OF] %s" % token_index
                    position = token_index + len(token)
                pass
            if size == 0:
                index += 1
            else:
                index += size
        #! print "index %s position %s" % (index, position)
        return True

ANY_ALL = [ (ACL.ALLOW, '*', '*') ]


class RemoteException(Exception):
    '''
    Base exception for RPC. This exception is raised when a problem
    occurs in the network layer.
    '''

    def __init__(self, message="", cause=None):
        '''
        Initializes a new RemoteException.

        Arguments:
            message -- The message accompanying this exception.
            cause -- The underlying cause of this exception.
        '''
        self._message = message
        self._cause = cause
        pass

    def __str__(self):
        return repr(self._message)

    def get_message(self):
        return self._message

    def get_cause(self):
        return self._cause



class InvocationException(RemoteException):
    '''
    Exception raised when a problem occurs during the remote invocation
    of a method.
    '''
    pass



class AuthorizationException(RemoteException):
    '''
    Exception raised when the caller is not authorized to invoke the
    remote method.
    '''
    pass


class TimeoutException(Exception):
    '''
    Exception raised when the synchronous execution of a method takes
    longer than the given threshold because an underlying asynchronous
    reply did not arrive in time.
    '''
    pass


class Callback(object):
    '''
    A base class for callback handlers.
    '''
    __metaclass__ = abc.ABCMeta


    @abc.abstractproperty
    def set_value(self, value):
        return NotImplemented

    @abc.abstractproperty
    def cancel_with_error(self, exception):
        return NotImplemented


class Future(Callback):
    '''
    Represents the result of an asynchronous computation.
    '''

    def __init__(self):
        '''
        Initializes a new Future.
        '''
        self._value = None
        self._exception = None
        self._event = threading.Event()
        pass

    def set_value(self, value):
        '''
        Sets the value of this Future. Once the value is set, a caller
        blocked on get_value will be able to continue.
        '''
        self._value = value
        self._event.set()

    def get_value(self, timeout=None):
        '''
        Gets the value of this Future. This call will block until
        the result is available, or until an optional timeout expires.
        When this Future is cancelled with an error,

        Arguments:
            timeout -- The maximum waiting time to obtain the value.
        '''
        self._event.wait(timeout)
        if self._exception:
            raise self._exception
        if not self._event.is_set():
            raise TimeoutException
        return self._value

    def is_done(self):
        '''
        Returns true if a value has been returned.
        '''
        return self._event.is_set()

    def cancel_with_error(self, exception):
        '''
        Cancels the Future because of an error. Once cancelled, a
        caller blocked on get_value will be able to continue.
        '''
        self._exception = exception
        self._event.set()



class Endpoint(object):
    '''
    The Endpoint class is an abstract base class for all objects
    participating in an RPC-enabled XMPP network.

    A user subclassing this class is required to implement the method:
        FQN(self)
    where FQN stands for Fully Qualified Name, an unambiguous name
    which specifies which object an RPC call refers to. It is the
    first part in a RPC method name '<fqn>.<method>'.
    '''
    __metaclass__ = abc.ABCMeta


    def __init__(self, session, target_jid):
        '''
        Initialize a new Endpoint. This constructor should never be
        invoked by a user, instead it will be called by the factories
        which instantiate the RPC-enabled objects, of which only
        the classes are provided by the user.

        Arguments:
            session -- An RPC session instance.
            target_jid -- the identity of the remote XMPP entity.
        '''
        self.session = session
        self.target_jid = target_jid

    @abc.abstractproperty
    def FQN(self):
        return NotImplemented

    def get_methods(self):
        '''
        Returns a dictionary of all RPC method names provided by this
        class. This method returns the actual  method names as found
        in the class definition which have been decorated with:

            @remote
            def some_rpc_method(arg1, arg2)


        Unless:
            (1) the name has been remapped, in which case the new
                name will be returned.

                    @remote("new_name")
                    def some_rpc_method(arg1, arg2)

            (2) the method is set to hidden

                    @remote(False)
                    def some_hidden_method(arg1, arg2)
        '''
        result = dict()
        for function in dir(self):
            test_attr = getattr(self, function, None)
            try:
                if test_attr._rpc:
                    result[test_attr._rpc_name] = test_attr
            except Exception:
                pass
        return result



class Proxy(Endpoint):
    '''
    Implementation of the Proxy pattern which is intended to wrap
    around Endpoints in order to intercept calls, marshall them and
    forward them to the remote object.
    '''

    def __init__(self, endpoint, callback = None):
        '''
        Initializes a new Proxy.

        Arguments:
            endpoint -- The endpoint which is proxified.
        '''
        self._endpoint = endpoint
        self._callback = callback

    def __getattribute__(self, name, *args):
        if name in ('__dict__', '_endpoint', 'async', '_callback'):
            return object.__getattribute__(self, name)
        else:
            attribute = self._endpoint.__getattribute__(name)
            if hasattr(attribute, '__call__'):
                try:
                    if attribute._rpc:
                        def _remote_call(*args, **kwargs):
                            log.debug("Remotely calling '%s.%s' with arguments %s.", self._endpoint.FQN(), attribute._rpc_name, args)
                            return self._endpoint.session._call_remote(self._endpoint.target_jid, "%s.%s" % (self._endpoint.FQN(), attribute._rpc_name), self._callback, *args, **kwargs)
                        return _remote_call
                except:
                    pass   # If the attribute doesn't exist, don't care!
            return attribute

    def async(self, callback):
        return Proxy(self._endpoint, callback)

    def get_endpoint(self):
        '''
        Returns the proxified endpoint.
        '''
        return self._endpoint

    def FQN(self):
        return self._endpoint.FQN()


class JabberRPCEntry(object):


    def __init__(self, endpoint_FQN, call):
        self._endpoint_FQN = endpoint_FQN
        self._call = call

    def call_method(self, args):
        return_value = self._call(*args)
        if return_value is None:
            return return_value
        else:
            return self._return(return_value)

    def get_endpoint_FQN(self):
        return self._endpoint_FQN

    def _return(self, *args):
        return args


class RemoteSession(object):
    '''
    A context object for a Jabber-RPC session.
    '''


    def __init__(self, client, session_close_callback):
        '''
        Initializes a new RPC session.

        Arguments:
            client -- The Slixmpp client associated with this session.
            session_close_callback -- A callback called when the
                session is closed.
        '''
        self._client = client
        self._session_close_callback = session_close_callback
        self._event = threading.Event()
        self._entries = {}
        self._callbacks = {}
        self._acls = {}
        self._lock = RLock()

    def _wait(self):
        self._event.wait()

    def _notify(self, event):
        log.debug("RPC Session as %s started.", self._client.boundjid.full)
        self._client.send_presence()
        self._event.set()
        pass

    def _register_call(self, endpoint, method, name=None):
        '''
        Registers a method from an endpoint as remotely callable.
        '''
        if name is None:
            name = method.__name__
        key = "%s.%s" % (endpoint, name)
        log.debug("Registering call handler for %s (%s).", key, method)
        with self._lock:
            if key in self._entries:
                raise KeyError("A handler for %s has already been regisered!" % endpoint)
            self._entries[key] = JabberRPCEntry(endpoint, method)
        return key

    def _register_acl(self, endpoint, acl):
        log.debug("Registering ACL %s for endpoint %s.", repr(acl), endpoint)
        with self._lock:
            self._acls[endpoint] = acl

    def _register_callback(self, pid, callback):
        with self._lock:
            self._callbacks[pid] = callback

    def forget_callback(self, callback):
        with self._lock:
            pid = self._find_key(self._callbacks, callback)
            if pid is not None:
                del self._callback[pid]
            else:
                raise ValueError("Unknown callback!")
        pass

    def _find_key(self, dict, value):
        """return the key of dictionary dic given the value"""
        search = [k for k, v in dict.iteritems() if v == value]
        if len(search) == 0:
            return None
        else:
            return search[0]

    def _unregister_call(self, key):
        #removes the registered call
        with self._lock:
            if self._entries[key]:
                del self._entries[key]
            else:
                raise ValueError()

    def new_proxy(self, target_jid, endpoint_cls):
        '''
        Instantiates a new proxy object, which proxies to a remote
        endpoint. This method uses a class reference without
        constructor arguments to instantiate the proxy.

        Arguments:
            target_jid -- the XMPP entity ID hosting the endpoint.
            endpoint_cls -- The remote (duck) type.
        '''
        try:
            argspec = inspect.getargspec(endpoint_cls.__init__)
            args = [None] * (len(argspec[0]) - 1)
            result = endpoint_cls(*args)
            Endpoint.__init__(result, self, target_jid)
            return Proxy(result)
        except:
            traceback.print_exc(file=sys.stdout)

    def new_handler(self, acl, handler_cls, *args, **kwargs):
        '''
        Instantiates a new handler object, which is called remotely
        by others. The user can control the effect of the call by
        implementing the remote method in the local endpoint class. The
        returned reference can be called locally and will behave as a
        regular instance.

        Arguments:
            acl -- Access control list (see ACL class)
            handler_clss -- The local (duck) type.
            *args -- Constructor arguments for the local type.
            **kwargs -- Constructor keyworded arguments for the local
                type.
        '''
        argspec = inspect.getargspec(handler_cls.__init__)
        base_argspec = inspect.getargspec(Endpoint.__init__)
        if(argspec == base_argspec):
            result = handler_cls(self, self._client.boundjid.full)
        else:
            result = handler_cls(*args, **kwargs)
            Endpoint.__init__(result, self, self._client.boundjid.full)
        method_dict = result.get_methods()
        for method_name, method in method_dict.iteritems():
            #!!! self._client.plugin['xep_0009'].register_call(result.FQN(), method, method_name)
            self._register_call(result.FQN(), method, method_name)
        self._register_acl(result.FQN(), acl)
        return result

#    def is_available(self, targetCls, pto):
#        return self._client.is_available(pto)

    def _call_remote(self, pto, pmethod, callback, *arguments):
        iq = self._client.plugin['xep_0009'].make_iq_method_call(pto, pmethod, py2xml(*arguments))
        pid = iq['id']
        if callback is None:
            future = Future()
            self._register_callback(pid, future)
            iq.send()
            return future.get_value(30)
        else:
            log.debug("[RemoteSession] _call_remote %s", callback)
            self._register_callback(pid, callback)
            iq.send()

    def close(self):
        '''
        Closes this session.
        '''
        self._client.disconnect(False)
        self._session_close_callback()

    def _on_jabber_rpc_method_call(self, iq):
        iq.enable('rpc_query')
        params = iq['rpc_query']['method_call']['params']
        args = xml2py(params)
        pmethod = iq['rpc_query']['method_call']['method_name']
        try:
            with self._lock:
                entry = self._entries[pmethod]
                rules = self._acls[entry.get_endpoint_FQN()]
            if ACL.check(rules, iq['from'], pmethod):
                return_value = entry.call_method(args)
            else:
                raise AuthorizationException("Unauthorized access to %s from %s!" % (pmethod, iq['from']))
            if return_value is None:
                return_value = ()
            response = self._client.plugin['xep_0009'].make_iq_method_response(iq['id'], iq['from'], py2xml(*return_value))
            response.send()
        except InvocationException as ie:
            fault = dict()
            fault['code'] = 500
            fault['string'] = ie.get_message()
            self._client.plugin['xep_0009']._send_fault(iq, fault2xml(fault))
        except AuthorizationException as ae:
            log.error(ae.get_message())
            error = self._client.plugin['xep_0009']._forbidden(iq)
            error.send()
        except Exception as e:
            if isinstance(e, KeyError):
                log.error("No handler available for %s!", pmethod)
                error = self._client.plugin['xep_0009']._item_not_found(iq)
            else:
                traceback.print_exc(file=sys.stderr)
                log.error("An unexpected problem occurred invoking method %s!", pmethod)
                error = self._client.plugin['xep_0009']._undefined_condition(iq)
            #! print "[REMOTE.PY] _handle_remote_procedure_call AN ERROR SHOULD BE SENT NOW %s " % e
            error.send()

    def _on_jabber_rpc_method_response(self, iq):
        iq.enable('rpc_query')
        args = xml2py(iq['rpc_query']['method_response']['params'])
        pid = iq['id']
        with self._lock:
            callback = self._callbacks[pid]
            del self._callbacks[pid]
        if(len(args) > 0):
            callback.set_value(args[0])
        else:
            callback.set_value(None)
        pass

    def _on_jabber_rpc_method_response2(self, iq):
        iq.enable('rpc_query')
        if iq['rpc_query']['method_response']['fault'] is not None:
            self._on_jabber_rpc_method_fault(iq)
        else:
            args = xml2py(iq['rpc_query']['method_response']['params'])
            pid = iq['id']
            with self._lock:
                callback = self._callbacks[pid]
                del self._callbacks[pid]
            if(len(args) > 0):
                callback.set_value(args[0])
            else:
                callback.set_value(None)
            pass

    def _on_jabber_rpc_method_fault(self, iq):
        iq.enable('rpc_query')
        fault = xml2fault(iq['rpc_query']['method_response']['fault'])
        pid = iq['id']
        with self._lock:
            callback = self._callbacks[pid]
            del self._callbacks[pid]
        e = {
             500: InvocationException
        }[fault['code']](fault['string'])
        callback.cancel_with_error(e)

    def _on_jabber_rpc_error(self, iq):
        pid = iq['id']
        pmethod = self._client.plugin['xep_0009']._extract_method(iq['rpc_query'])
        code = iq['error']['code']
        type = iq['error']['type']
        condition = iq['error']['condition']
        #! print("['REMOTE.PY']._BINDING_handle_remote_procedure_error -> ERROR! ERROR! ERROR! Condition is '%s'" % condition)
        with self._lock:
            callback = self._callbacks[pid]
            del self._callbacks[pid]
        e = {
            'item-not-found': RemoteException("No remote handler available for %s at %s!" % (pmethod, iq['from'])),
            'forbidden': AuthorizationException("Forbidden to invoke remote handler for %s at %s!" % (pmethod, iq['from'])),
            'undefined-condition': RemoteException("An unexpected problem occured trying to invoke %s at %s!" % (pmethod, iq['from'])),
        }[condition]
        if e is None:
            RemoteException("An unexpected exception occurred at %s!" % iq['from'])
        callback.cancel_with_error(e)


class Remote(object):
    '''
    Bootstrap class for Jabber-RPC sessions. New sessions are openend
    with an existing XMPP client, or one is instantiated on demand.
    '''
    _instance = None
    _sessions = dict()
    _lock = threading.RLock()

    @classmethod
    def new_session_with_client(cls, client, callback=None):
        '''
        Opens a new session with a given client.

        Arguments:
            client -- An XMPP client.
            callback -- An optional callback which can be used to track
                the starting state of the session.
        '''
        with Remote._lock:
            if(client.boundjid.bare in cls._sessions):
                raise RemoteException("There already is a session associated with these credentials!")
            else:
                cls._sessions[client.boundjid.bare] = client;
        def _session_close_callback():
            with Remote._lock:
                del cls._sessions[client.boundjid.bare]
        result = RemoteSession(client, _session_close_callback)
        client.plugin['xep_0009'].xmpp.add_event_handler('jabber_rpc_method_call', result._on_jabber_rpc_method_call, threaded=True)
        client.plugin['xep_0009'].xmpp.add_event_handler('jabber_rpc_method_response', result._on_jabber_rpc_method_response, threaded=True)
        client.plugin['xep_0009'].xmpp.add_event_handler('jabber_rpc_method_fault', result._on_jabber_rpc_method_fault, threaded=True)
        client.plugin['xep_0009'].xmpp.add_event_handler('jabber_rpc_error', result._on_jabber_rpc_error, threaded=True)
        if callback is None:
            start_event_handler = result._notify
        else:
            start_event_handler = callback
        client.add_event_handler("session_start", start_event_handler)
        if client.connect():
            client.process(threaded=True)
        else:
            raise RemoteException("Could not connect to XMPP server!")
        pass
        if callback is None:
            result._wait()
        return result

    @classmethod
    def new_session(cls, jid, password, callback=None):
        '''
        Opens a new session and instantiates a new XMPP client.

        Arguments:
            jid -- The XMPP JID for logging in.
            password -- The password for logging in.
            callback -- An optional callback which can be used to track
                the starting state of the session.
        '''
        client = slixmpp.ClientXMPP(jid, password)
        #? Register plug-ins.
        client.register_plugin('xep_0004') # Data Forms
        client.register_plugin('xep_0009') # Jabber-RPC
        client.register_plugin('xep_0030') # Service Discovery
        client.register_plugin('xep_0060') # PubSub
        client.register_plugin('xep_0199') # XMPP Ping
        return cls.new_session_with_client(client, callback)