2 """The KRPC communication protocol implementation.
4 @var UDP_PACKET_LIMIT: the maximum number of bytes that can be sent in a
5 UDP packet without fragmentation
7 @var KRPC_ERROR: the code for a generic error
8 @var KRPC_ERROR_SERVER_ERROR: the code for a server error
9 @var KRPC_ERROR_MALFORMED_PACKET: the code for a malformed packet error
10 @var KRPC_ERROR_METHOD_UNKNOWN: the code for a method unknown error
11 @var KRPC_ERROR_MALFORMED_REQUEST: the code for a malformed request error
12 @var KRPC_ERROR_INVALID_TOKEN: the code for an invalid token error
13 @var KRPC_ERROR_RESPONSE_TOO_LONG: the code for a response too long error
15 @var KRPC_ERROR_INTERNAL: the code for an internal error
16 @var KRPC_ERROR_RECEIVED_UNKNOWN: the code for an unknown message type error
17 @var KRPC_ERROR_TIMEOUT: the code for a timeout error
18 @var KRPC_ERROR_PROTOCOL_STOPPED: the code for a stopped protocol error
20 @var TID: the identifier for the transaction ID
21 @var REQ: the identifier for a request packet
22 @var RSP: the identifier for a response packet
23 @var TYP: the identifier for the type of packet
24 @var ARG: the identifier for the argument to the request
25 @var ERR: the identifier for an error packet
27 @group Remote node error codes: KRPC_ERROR, KRPC_ERROR_SERVER_ERROR,
28 KRPC_ERROR_MALFORMED_PACKET, KRPC_ERROR_METHOD_UNKNOWN,
29 KRPC_ERROR_MALFORMED_REQUEST, KRPC_ERROR_INVALID_TOKEN,
30 KRPC_ERROR_RESPONSE_TOO_LONG
31 @group Local node error codes: KRPC_ERROR_INTERNAL, KRPC_ERROR_RECEIVED_UNKNOWN,
32 KRPC_ERROR_TIMEOUT, KRPC_ERROR_PROTOCOL_STOPPED
33 @group Command identifiers: TID, REQ, RSP, TYP, ARG, ERR
37 from bencode import bencode, bdecode
38 from datetime import datetime, timedelta
41 from twisted.internet import defer
42 from twisted.internet import protocol, reactor
43 from twisted.python import log
44 from twisted.trial import unittest
46 from khash import newID
48 UDP_PACKET_LIMIT = 1472
52 KRPC_ERROR_SERVER_ERROR = 201
53 KRPC_ERROR_MALFORMED_PACKET = 202
54 KRPC_ERROR_METHOD_UNKNOWN = 203
55 KRPC_ERROR_MALFORMED_REQUEST = 204
56 KRPC_ERROR_INVALID_TOKEN = 205
57 KRPC_ERROR_RESPONSE_TOO_LONG = 206
60 KRPC_ERROR_INTERNAL = 100
61 KRPC_ERROR_RECEIVED_UNKNOWN = 101
62 KRPC_ERROR_TIMEOUT = 102
63 KRPC_ERROR_PROTOCOL_STOPPED = 103
73 class KrpcError(Exception):
74 """An error occurred in the KRPC protocol."""
77 def verifyMessage(msg):
78 """Check received message for corruption and errors.
80 @type msg: C{dictionary}
81 @param msg: the dictionary of information received on the connection
82 @raise KrpcError: if the message is corrupt
86 raise KrpcError, (KRPC_ERROR_MALFORMED_PACKET, "not a dictionary")
88 raise KrpcError, (KRPC_ERROR_MALFORMED_PACKET, "no message type")
91 raise KrpcError, (KRPC_ERROR_MALFORMED_PACKET, "request type not specified")
92 if type(msg[REQ]) != str:
93 raise KrpcError, (KRPC_ERROR_MALFORMED_PACKET, "request type is not a string")
95 raise KrpcError, (KRPC_ERROR_MALFORMED_PACKET, "no arguments for request")
96 if type(msg[ARG]) != dict:
97 raise KrpcError, (KRPC_ERROR_MALFORMED_PACKET, "arguments for request are not in a dictionary")
100 raise KrpcError, (KRPC_ERROR_MALFORMED_PACKET, "response not specified")
101 if type(msg[RSP]) != dict:
102 raise KrpcError, (KRPC_ERROR_MALFORMED_PACKET, "response is not a dictionary")
103 elif msg[TYP] == ERR:
105 raise KrpcError, (KRPC_ERROR_MALFORMED_PACKET, "error not specified")
106 if type(msg[ERR]) != list:
107 raise KrpcError, (KRPC_ERROR_MALFORMED_PACKET, "error is not a list")
108 if len(msg[ERR]) != 2:
109 raise KrpcError, (KRPC_ERROR_MALFORMED_PACKET, "error is not a 2-element list")
110 if type(msg[ERR][0]) not in (int, long):
111 raise KrpcError, (KRPC_ERROR_MALFORMED_PACKET, "error number is not a number")
112 if type(msg[ERR][1]) != str:
113 raise KrpcError, (KRPC_ERROR_MALFORMED_PACKET, "error string is not a string")
115 # raise KrpcError, (KRPC_ERROR_MALFORMED_PACKET, "unknown message type")
117 raise KrpcError, (KRPC_ERROR_MALFORMED_PACKET, "no transaction ID specified")
118 if type(msg[TID]) != str:
119 raise KrpcError, (KRPC_ERROR_MALFORMED_PACKET, "transaction id is not a string")
121 class hostbroker(protocol.DatagramProtocol):
122 """The factory for the KRPC protocol.
124 @type server: L{khashmir.Khashmir}
125 @ivar server: the main Khashmir program
126 @type stats: L{stats.StatsLogger}
127 @ivar stats: the statistics logger to save transport info
128 @type config: C{dictionary}
129 @ivar config: the configuration parameters for the DHT
130 @type connections: C{dictionary}
131 @ivar connections: all the connections that have ever been made to the
132 protocol, keys are IP address and port pairs, values are L{KRPC}
133 protocols for the addresses
134 @ivar protocol: the protocol to use to handle incoming connections
136 @type addr: (C{string}, C{int})
137 @ivar addr: the IP address and port of this node
140 def __init__(self, server, stats, config):
141 """Initialize the factory.
143 @type server: L{khashmir.Khashmir}
144 @param server: the main DHT program
145 @type stats: L{stats.StatsLogger}
146 @param stats: the statistics logger to save transport info
147 @type config: C{dictionary}
148 @param config: the configuration parameters for the DHT
153 # this should be changed to storage that drops old entries
154 self.connections = {}
156 def datagramReceived(self, datagram, addr):
157 """Optionally create a new protocol object, and handle the new datagram.
159 @type datagram: C{string}
160 @param datagram: the data received from the transport.
161 @type addr: (C{string}, C{int})
162 @param addr: source IP address and port of datagram.
164 c = self.connectionForAddr(addr)
165 c.datagramReceived(datagram, addr)
167 # del self.connections[addr]
169 def connectionForAddr(self, addr):
170 """Get a protocol object for the source.
172 @type addr: (C{string}, C{int})
173 @param addr: source IP address and port of datagram.
175 # Don't connect to ourself
176 if addr == self.addr:
179 # Create a new protocol object if necessary
180 if not self.connections.has_key(addr):
181 conn = self.protocol(addr, self.server, self.stats, self.transport, self.config)
182 self.connections[addr] = conn
184 conn = self.connections[addr]
187 def makeConnection(self, transport):
188 """Make a connection to a transport and save our address."""
189 protocol.DatagramProtocol.makeConnection(self, transport)
190 tup = transport.getHost()
191 self.addr = (tup.host, tup.port)
193 def stopProtocol(self):
194 """Stop all the open connections."""
195 for conn in self.connections.values():
197 protocol.DatagramProtocol.stopProtocol(self)
199 class KrpcRequest(defer.Deferred):
200 """An outstanding request to a remote node.
202 @type protocol: L{KRPC}
203 @ivar protocol: the protocol to send data with
204 @ivar tid: the transaction ID of the request
205 @type method: C{string}
206 @ivar method: the name of the method to call on the remote node
207 @type data: C{string}
208 @ivar data: the message to send to the remote node
209 @type config: C{dictionary}
210 @ivar config: the configuration parameters for the DHT
212 @ivar delay: the last timeout delay sent
213 @type start: C{datetime}
214 @ivar start: the time to request was started at
215 @type laterNextTimeout: L{twisted.internet.interfaces.IDelayedCall}
216 @ivar laterNextTimeout: the pending call to timeout the last sent request
217 @type laterFinalTimeout: L{twisted.internet.interfaces.IDelayedCall}
218 @ivar laterFinalTimeout: the pending call to timeout the entire request
221 def __init__(self, protocol, newTID, method, data, config):
222 """Initialize the request, and send it out.
224 @type protocol: L{KRPC}
225 @param protocol: the protocol to send data with
226 @param newTID: the transaction ID of the request
227 @type method: C{string}
228 @param method: the name of the method to call on the remote node
229 @type data: C{string}
230 @param data: the message to send to the remote node
231 @type config: C{dictionary}
232 @param config: the configuration parameters for the DHT
234 defer.Deferred.__init__(self)
235 self.protocol = protocol
240 self.delay = self.config.get('KRPC_INITIAL_DELAY', 2)
241 self.start = datetime.now()
242 self.laterNextTimeout = None
243 self.laterFinalTimeout = reactor.callLater(self.config.get('KRPC_TIMEOUT', 9), self.finalTimeout)
244 reactor.callLater(0, self.send)
247 """Send the request to the remote node."""
248 assert not self.laterNextTimeout, 'There is already a pending request'
249 self.laterNextTimeout = reactor.callLater(self.delay, self.nextTimeout)
251 self.protocol.sendData(self.method, self.data)
255 def nextTimeout(self):
256 """Check for a unrecoverable timeout, otherwise resend."""
257 self.laterNextTimeout = None
258 if datetime.now() - self.start > timedelta(seconds = self.config.get('KRPC_TIMEOUT', 9)):
260 elif self.protocol.stopped:
261 log.msg('Timeout but can not resend %r, protocol has been stopped' % self.tid)
264 log.msg('Trying to resend %r now with delay %d sec' % (self.tid, self.delay))
265 reactor.callLater(0, self.send)
267 def finalTimeout(self):
268 """Timeout the request after an unrecoverable timeout."""
270 delay = datetime.now() - self.start
271 log.msg('%r timed out after %0.2f sec' %
272 (self.tid, delay.seconds + delay.microseconds/1000000.0))
273 self.protocol.timeOut(self.tid, self.method)
275 def callback(self, resp):
277 defer.Deferred.callback(self, resp)
279 def errback(self, resp):
281 defer.Deferred.errback(self, resp)
283 def dropTimeOut(self):
284 """Cancel the timeout call when a response is received."""
285 if self.laterFinalTimeout and self.laterFinalTimeout.active():
286 self.laterFinalTimeout.cancel()
287 self.laterFinalTimeout = None
288 if self.laterNextTimeout and self.laterNextTimeout.active():
289 self.laterNextTimeout.cancel()
290 self.laterNextTimeout = None
293 """The KRPC protocol implementation.
295 @ivar transport: the transport to use for the protocol
296 @type factory: L{khashmir.Khashmir}
297 @ivar factory: the main Khashmir program
298 @type stats: L{stats.StatsLogger}
299 @ivar stats: the statistics logger to save transport info
300 @type addr: (C{string}, C{int})
301 @ivar addr: the IP address and port of the source node
302 @type config: C{dictionary}
303 @ivar config: the configuration parameters for the DHT
304 @type tids: C{dictionary}
305 @ivar tids: the transaction IDs outstanding for requests, keys are the
306 transaction ID of the request, values are the deferreds to call with
308 @type stopped: C{boolean}
309 @ivar stopped: whether the protocol has been stopped
312 def __init__(self, addr, server, stats, transport, config = {}):
313 """Initialize the protocol.
315 @type addr: (C{string}, C{int})
316 @param addr: the IP address and port of the source node
317 @type server: L{khashmir.Khashmir}
318 @param server: the main Khashmir program
319 @type stats: L{stats.StatsLogger}
320 @param stats: the statistics logger to save transport info
321 @param transport: the transport to use for the protocol
322 @type config: C{dictionary}
323 @param config: the configuration parameters for the DHT
324 (optional, defaults to using defaults)
326 self.transport = transport
327 self.factory = server
334 def datagramReceived(self, data, addr):
335 """Process the new datagram.
337 @type data: C{string}
338 @param data: the data received from the transport.
339 @type addr: (C{string}, C{int})
340 @param addr: source IP address and port of datagram.
342 self.stats.receivedBytes(len(data))
344 if self.config.get('SPEW', False):
345 log.msg("stopped, dropping message from %r: %s" % (addr, data))
347 # Bdecode the message
351 if self.config.get('SPEW', False):
352 log.msg("krpc bdecode error: ")
356 # Make sure the remote node isn't trying anything funny
360 log.msg("krpc message verification error: ")
364 if self.config.get('SPEW', False):
365 log.msg("%d received from %r: %s" % (self.factory.port, addr, msg))
367 # Process it based on its type
371 # Requests are handled by the factory
372 f = getattr(self.factory ,"krpc_" + msg[REQ], None)
373 msg[ARG]['_krpc_sender'] = self.addr
374 if f and callable(f):
375 self.stats.receivedAction(msg[REQ])
377 ret = f(*(), **msg[ARG])
379 log.msg('Got a Krpc error while running: krpc_%s' % msg[REQ])
380 if e[0] != KRPC_ERROR_INVALID_TOKEN:
382 self.stats.errorAction(msg[REQ])
383 olen = self._sendResponse(msg[REQ], addr, msg[TID], ERR,
386 log.msg('Got a malformed request for: krpc_%s' % msg[REQ])
388 self.stats.errorAction(msg[REQ])
389 olen = self._sendResponse(msg[REQ], addr, msg[TID], ERR,
390 [KRPC_ERROR_MALFORMED_REQUEST, str(e)])
392 log.msg('Got an unknown error while running: krpc_%s' % msg[REQ])
394 self.stats.errorAction(msg[REQ])
395 olen = self._sendResponse(msg[REQ], addr, msg[TID], ERR,
396 [KRPC_ERROR_SERVER_ERROR, str(e)])
398 olen = self._sendResponse(msg[REQ], addr, msg[TID], RSP, ret)
400 # Request for unknown method
401 log.msg("ERROR: don't know about method %s" % msg[REQ])
402 self.stats.receivedAction('unknown')
403 olen = self._sendResponse(msg[REQ], addr, msg[TID], ERR,
404 [KRPC_ERROR_METHOD_UNKNOWN, "unknown method "+str(msg[REQ])])
406 log.msg("%s >>> %s %s %s" % (addr, ilen, msg[REQ], olen))
407 elif msg[TYP] == RSP:
408 # Responses get processed by their TID's deferred
409 if self.tids.has_key(msg[TID]):
410 req = self.tids[msg[TID]]
412 del(self.tids[msg[TID]])
413 msg[RSP]['_krpc_sender'] = addr
414 req.callback(msg[RSP])
416 # no tid, this transaction was finished already...
417 if self.config.get('SPEW', False):
418 log.msg('received response from %r for completed request: %r' %
419 (msg[RSP]['id'], msg[TID]))
420 elif msg[TYP] == ERR:
421 # Errors get processed by their TID's deferred's errback
422 if self.tids.has_key(msg[TID]):
423 req = self.tids[msg[TID]]
424 del(self.tids[msg[TID]])
426 req.errback(KrpcError(*msg[ERR]))
428 # no tid, this transaction was finished already...
429 log.msg('received an error %r from %r for completed request: %r' %
430 (msg[ERR], msg[RSP]['id'], msg[TID]))
432 # Received an unknown message type
433 if self.config.get('SPEW', False):
434 log.msg("unknown message type: %r" % msg)
435 if msg[TID] in self.tids:
436 req = self.tids[msg[TID]]
437 del(self.tids[msg[TID]])
439 req.errback(KrpcError(KRPC_ERROR_RECEIVED_UNKNOWN,
440 "Received an unknown message type: %r" % msg[TYP]))
442 def _sendResponse(self, request, addr, tid, msgType, response):
443 """Helper function for sending responses to nodes.
445 @param request: the name of the requested method
446 @type addr: (C{string}, C{int})
447 @param addr: source IP address and port of datagram.
448 @param tid: the transaction ID of the request
449 @param msgType: the type of message to respond with
450 @param response: the arguments for the response
456 # Create the response message
457 msg = {TID : tid, TYP : msgType, msgType : response}
459 if self.config.get('SPEW', False):
460 log.msg("%d responding to %r: %s" % (self.factory.port, addr, msg))
464 # Make sure its not too long
465 if len(out) > UDP_PACKET_LIMIT:
466 # Can we remove some values to shorten it?
467 if 'values' in response:
468 # Save the original list of values
469 orig_values = response['values']
470 len_orig_values = len(bencode(orig_values))
472 # Caclulate the maximum value length possible
473 max_len_values = len_orig_values - (len(out) - UDP_PACKET_LIMIT)
474 assert max_len_values > 0
476 # Start with a calculation of how many values should be included
477 # (assumes all values are the same length)
478 per_value = (float(len_orig_values) - 2.0) / float(len(orig_values))
479 num_values = len(orig_values) - int(ceil(float(len(out) - UDP_PACKET_LIMIT) / per_value))
481 # Do a linear search for the actual maximum number possible
482 bencoded_values = len(bencode(orig_values[:num_values]))
483 while bencoded_values < max_len_values and num_values + 1 < len(orig_values):
484 bencoded_values += len(bencode(orig_values[num_values]))
486 while bencoded_values > max_len_values and num_values > 0:
488 bencoded_values -= len(bencode(orig_values[num_values]))
489 assert num_values > 0
492 response['values'] = orig_values[:num_values]
494 assert len(out) < UDP_PACKET_LIMIT
495 log.msg('Shortened a long packet from %d to %d values, new packet length: %d' %
496 (len(orig_values), num_values, len(out)))
498 # Too long a response, send an error
499 log.msg('Could not send response, too long: %d bytes' % len(out))
500 self.stats.errorAction(request)
501 msg = {TID : tid, TYP : ERR, ERR : [KRPC_ERROR_RESPONSE_TOO_LONG, "response was %d bytes" % len(out)]}
505 # Unknown error, send an error message
506 self.stats.errorAction(request)
507 msg = {TID : tid, TYP : ERR, ERR : [KRPC_ERROR_SERVER_ERROR, "unknown error sending response: %s" % str(e)]}
510 self.stats.sentBytes(len(out))
511 self.transport.write(out, addr)
514 def sendRequest(self, method, args):
515 """Send a request to the remote node.
517 @type method: C{string}
518 @param method: the method name to call on the remote node
519 @param args: the arguments to send to the remote node's method
522 return defer.fail(KrpcError(KRPC_ERROR_PROTOCOL_STOPPED,
523 "cannot send, connection has been stopped"))
525 # Create the request message
527 msg = {TID : newTID, TYP : REQ, REQ : method, ARG : args}
528 if self.config.get('SPEW', False):
529 log.msg("%d sending to %r: %s" % (self.factory.port, self.addr, msg))
532 # Create the request object and save it with the TID
533 req = KrpcRequest(self, newTID, method, data, self.config)
534 self.tids[newTID] = req
536 # Save the conclusion of the action
537 req.addCallbacks(self.stats.responseAction, self.stats.failedAction,
538 callbackArgs = (method, datetime.now()),
539 errbackArgs = (method, datetime.now()))
543 def sendData(self, method, data):
544 """Write a request to the transport and save the stats.
546 @type method: C{string}
547 @param method: the name of the method to call on the remote node
548 @type data: C{string}
549 @param data: the message to send to the remote node
551 self.transport.write(data, self.addr)
552 self.stats.sentAction(method)
553 self.stats.sentBytes(len(data))
555 def timeOut(self, badTID, method):
556 """Call the deferred's errback if a timeout occurs.
558 @param badTID: the transaction ID of the request
559 @type method: C{string}
560 @param method: the name of the method that timed out on the remote node
562 if badTID in self.tids:
563 req = self.tids[badTID]
564 del(self.tids[badTID])
565 req.errback(KrpcError(KRPC_ERROR_TIMEOUT, "timeout waiting for '%s' from %r" %
566 (method, self.addr)))
568 log.msg('Received a timeout for an unknown request for %s from %r' % (method, self.addr))
571 """Cancel all pending requests."""
572 for req in self.tids.values():
573 req.errback(KrpcError(KRPC_ERROR_PROTOCOL_STOPPED,
574 'connection has been stopped while waiting for response'))
578 #{ For testing the KRPC protocol
579 def connectionForAddr(host, port):
582 class Receiver(protocol.Factory):
586 def krpc_store(self, msg, _krpc_sender):
589 def krpc_echo(self, msg, _krpc_sender):
591 def krpc_values(self, length, num, _krpc_sender):
592 return {'values': ['1'*length]*num}
595 from stats import StatsLogger
597 a = hostbroker(af, StatsLogger(None, None),
598 {'KRPC_TIMEOUT': 9, 'KRPC_INITIAL_DELAY': 2, 'SPEW': False})
600 p = reactor.listenUDP(port, a)
603 class KRPCTests(unittest.TestCase):
607 self.af, self.a, self.ap = make(1180)
608 self.bf, self.b, self.bp = make(1181)
611 self.ap.stopListening()
612 self.bp.stopListening()
614 def bufEquals(self, result, value):
615 self.failUnlessEqual(self.bf.buf, value)
617 def testSimpleMessage(self):
618 d = self.a.connectionForAddr(('127.0.0.1', 1181)).sendRequest('store', {'msg' : "This is a test."})
619 d.addCallback(self.bufEquals, ["This is a test."])
622 def testMessageBlast(self):
624 d = self.a.connectionForAddr(('127.0.0.1', 1181)).sendRequest('store', {'msg' : "This is a test."})
625 d.addCallback(self.bufEquals, ["This is a test."] * 100)
629 df = self.a.connectionForAddr(('127.0.0.1', 1181)).sendRequest('echo', {'msg' : "This is a test."})
630 df.addCallback(self.gotMsg, "This is a test.")
633 def gotMsg(self, dict, should_be):
634 _krpc_sender = dict['_krpc_sender']
635 self.failUnlessEqual(dict['msg'], should_be)
637 def testManyEcho(self):
638 for i in xrange(100):
639 df = self.a.connectionForAddr(('127.0.0.1', 1181)).sendRequest('echo', {'msg' : "This is a test."})
640 df.addCallback(self.gotMsg, "This is a test.")
643 def testMultiEcho(self):
644 df = self.a.connectionForAddr(('127.0.0.1', 1181)).sendRequest('echo', {'msg' : "This is a test."})
645 df.addCallback(self.gotMsg, "This is a test.")
647 df = self.a.connectionForAddr(('127.0.0.1', 1181)).sendRequest('echo', {'msg' : "This is another test."})
648 df.addCallback(self.gotMsg, "This is another test.")
650 df = self.a.connectionForAddr(('127.0.0.1', 1181)).sendRequest('echo', {'msg' : "This is yet another test."})
651 df.addCallback(self.gotMsg, "This is yet another test.")
655 def testEchoReset(self):
656 df = self.a.connectionForAddr(('127.0.0.1', 1181)).sendRequest('echo', {'msg' : "This is a test."})
657 df.addCallback(self.gotMsg, "This is a test.")
659 df = self.a.connectionForAddr(('127.0.0.1', 1181)).sendRequest('echo', {'msg' : "This is another test."})
660 df.addCallback(self.gotMsg, "This is another test.")
661 df.addCallback(self.echoReset)
664 def echoReset(self, dict):
665 del(self.a.connections[('127.0.0.1', 1181)])
666 df = self.a.connectionForAddr(('127.0.0.1', 1181)).sendRequest('echo', {'msg' : "This is yet another test."})
667 df.addCallback(self.gotMsg, "This is yet another test.")
670 def testUnknownMeth(self):
671 df = self.a.connectionForAddr(('127.0.0.1', 1181)).sendRequest('blahblah', {'msg' : "This is a test."})
672 df = self.failUnlessFailure(df, KrpcError)
673 df.addBoth(self.gotErr, KRPC_ERROR_METHOD_UNKNOWN)
676 def testMalformedRequest(self):
677 df = self.a.connectionForAddr(('127.0.0.1', 1181)).sendRequest('echo', {'msg' : "This is a test.", 'foo': 'bar'})
678 df = self.failUnlessFailure(df, KrpcError)
679 df.addBoth(self.gotErr, KRPC_ERROR_MALFORMED_REQUEST, TypeError)
682 def gotErr(self, value, should_be, *errorTypes):
683 self.failUnlessEqual(value[0], should_be)
685 self.flushLoggedErrors(*errorTypes)
687 def testLongPackets(self):
688 df = self.a.connectionForAddr(('127.0.0.1', 1181)).sendRequest('values', {'length' : 1, 'num': 2000})
689 df.addCallback(self.gotLongRsp)
692 def gotLongRsp(self, dict):
693 # Not quite accurate, but good enough
694 self.failUnless(len(bencode(dict))-10 < UDP_PACKET_LIMIT)