8fe15f507b
The old code relied on the timing of DelayedCalls to see what had been called or not, but unfortunately we don't have a real-time OS so the timing on DelayedCalls can only be approximate. Changed to explicitly keep track of which calls had been made. This simplifies the shutdown logic drastically, and I believe we can take out the reactor.iterate() now
355 lines
15 KiB
Python
355 lines
15 KiB
Python
#!/usr/bin/env python
|
|
#
|
|
# This library is free software, distributed under the terms of
|
|
# the GNU Lesser General Public License Version 3, or any later version.
|
|
# See the COPYING file included in this archive
|
|
#
|
|
# The docstrings in this module contain epytext markup; API documentation
|
|
# may be created by processing this file with epydoc: http://epydoc.sf.net
|
|
|
|
import logging
|
|
import binascii
|
|
import time
|
|
|
|
from twisted.internet import protocol, defer
|
|
from twisted.python import failure
|
|
from twisted.internet import error
|
|
import twisted.internet.reactor
|
|
|
|
import constants
|
|
import encoding
|
|
import msgtypes
|
|
import msgformat
|
|
from contact import Contact
|
|
|
|
|
|
reactor = twisted.internet.reactor
|
|
log = logging.getLogger(__name__)
|
|
|
|
|
|
class TimeoutError(Exception):
|
|
""" Raised when a RPC times out """
|
|
def __init__(self, remote_contact_id):
|
|
# remote_contact_id is a binary blob so we need to convert it
|
|
# into something more readable
|
|
msg = 'Timeout connecting to {}'.format(binascii.hexlify(remote_contact_id))
|
|
Exception.__init__(self, msg)
|
|
self.remote_contact_id = remote_contact_id
|
|
|
|
|
|
class Delay(object):
|
|
maxToSendDelay = 10**-3 #0.05
|
|
minToSendDelay = 10**-5 #0.01
|
|
|
|
def __init__(self, start=0):
|
|
self._next = start
|
|
|
|
# TODO: explain why this logic is like it is. And add tests that
|
|
# show that it actually does what it needs to do.
|
|
def __call__(self):
|
|
ts = time.time()
|
|
delay = 0
|
|
if ts >= self._next:
|
|
delay = self.minToSendDelay
|
|
self._next = ts + self.minToSendDelay
|
|
else:
|
|
delay = (self._next - ts) + self.maxToSendDelay
|
|
self._next += self.maxToSendDelay
|
|
return delay
|
|
|
|
|
|
class KademliaProtocol(protocol.DatagramProtocol):
|
|
""" Implements all low-level network-related functions of a Kademlia node """
|
|
msgSizeLimit = constants.udpDatagramMaxSize-26
|
|
|
|
|
|
def __init__(self, node, msgEncoder=encoding.Bencode(),
|
|
msgTranslator=msgformat.DefaultFormat()):
|
|
self._node = node
|
|
self._encoder = msgEncoder
|
|
self._translator = msgTranslator
|
|
self._sentMessages = {}
|
|
self._partialMessages = {}
|
|
self._partialMessagesProgress = {}
|
|
self._delay = Delay()
|
|
# keep track of outstanding writes so that they
|
|
# can be cancelled on shutdown
|
|
self._call_later_list = {}
|
|
|
|
def sendRPC(self, contact, method, args, rawResponse=False):
|
|
""" Sends an RPC to the specified contact
|
|
|
|
@param contact: The contact (remote node) to send the RPC to
|
|
@type contact: kademlia.contacts.Contact
|
|
@param method: The name of remote method to invoke
|
|
@type method: str
|
|
@param args: A list of (non-keyword) arguments to pass to the remote
|
|
method, in the correct order
|
|
@type args: tuple
|
|
@param rawResponse: If this is set to C{True}, the caller of this RPC
|
|
will receive a tuple containing the actual response
|
|
message object and the originating address tuple as
|
|
a result; in other words, it will not be
|
|
interpreted by this class. Unless something special
|
|
needs to be done with the metadata associated with
|
|
the message, this should remain C{False}.
|
|
@type rawResponse: bool
|
|
|
|
@return: This immediately returns a deferred object, which will return
|
|
the result of the RPC call, or raise the relevant exception
|
|
if the remote node raised one. If C{rawResponse} is set to
|
|
C{True}, however, it will always return the actual response
|
|
message (which may be a C{ResponseMessage} or an
|
|
C{ErrorMessage}).
|
|
@rtype: twisted.internet.defer.Deferred
|
|
"""
|
|
msg = msgtypes.RequestMessage(self._node.id, method, args)
|
|
msgPrimitive = self._translator.toPrimitive(msg)
|
|
encodedMsg = self._encoder.encode(msgPrimitive)
|
|
|
|
df = defer.Deferred()
|
|
if rawResponse:
|
|
df._rpcRawResponse = True
|
|
|
|
# Set the RPC timeout timer
|
|
timeoutCall = reactor.callLater(
|
|
constants.rpcTimeout, self._msgTimeout, msg.id) #IGNORE:E1101
|
|
# Transmit the data
|
|
self._send(encodedMsg, msg.id, (contact.address, contact.port))
|
|
self._sentMessages[msg.id] = (contact.id, df, timeoutCall)
|
|
return df
|
|
|
|
def datagramReceived(self, datagram, address):
|
|
""" Handles and parses incoming RPC messages (and responses)
|
|
|
|
@note: This is automatically called by Twisted when the protocol
|
|
receives a UDP datagram
|
|
"""
|
|
if datagram[0] == '\x00' and datagram[25] == '\x00':
|
|
totalPackets = (ord(datagram[1]) << 8) | ord(datagram[2])
|
|
msgID = datagram[5:25]
|
|
seqNumber = (ord(datagram[3]) << 8) | ord(datagram[4])
|
|
if msgID not in self._partialMessages:
|
|
self._partialMessages[msgID] = {}
|
|
self._partialMessages[msgID][seqNumber] = datagram[26:]
|
|
if len(self._partialMessages[msgID]) == totalPackets:
|
|
keys = self._partialMessages[msgID].keys()
|
|
keys.sort()
|
|
data = ''
|
|
for key in keys:
|
|
data += self._partialMessages[msgID][key]
|
|
datagram = data
|
|
del self._partialMessages[msgID]
|
|
else:
|
|
return
|
|
try:
|
|
msgPrimitive = self._encoder.decode(datagram)
|
|
except encoding.DecodeError:
|
|
# We received some rubbish here
|
|
return
|
|
except IndexError:
|
|
log.warning("Couldn't decode dht datagram from %s", address)
|
|
return
|
|
|
|
message = self._translator.fromPrimitive(msgPrimitive)
|
|
remoteContact = Contact(message.nodeID, address[0], address[1], self)
|
|
|
|
# Refresh the remote node's details in the local node's k-buckets
|
|
self._node.addContact(remoteContact)
|
|
|
|
if isinstance(message, msgtypes.RequestMessage):
|
|
# This is an RPC method request
|
|
self._handleRPC(remoteContact, message.id, message.request, message.args)
|
|
elif isinstance(message, msgtypes.ResponseMessage):
|
|
# Find the message that triggered this response
|
|
if self._sentMessages.has_key(message.id):
|
|
# Cancel timeout timer for this RPC
|
|
df, timeoutCall = self._sentMessages[message.id][1:3]
|
|
timeoutCall.cancel()
|
|
del self._sentMessages[message.id]
|
|
|
|
if hasattr(df, '_rpcRawResponse'):
|
|
# The RPC requested that the raw response message
|
|
# and originating address be returned; do not
|
|
# interpret it
|
|
df.callback((message, address))
|
|
elif isinstance(message, msgtypes.ErrorMessage):
|
|
# The RPC request raised a remote exception; raise it locally
|
|
if message.exceptionType.startswith('exceptions.'):
|
|
exceptionClassName = message.exceptionType[11:]
|
|
else:
|
|
localModuleHierarchy = self.__module__.split('.')
|
|
remoteHierarchy = message.exceptionType.split('.')
|
|
#strip the remote hierarchy
|
|
while remoteHierarchy[0] == localModuleHierarchy[0]:
|
|
remoteHierarchy.pop(0)
|
|
localModuleHierarchy.pop(0)
|
|
exceptionClassName = '.'.join(remoteHierarchy)
|
|
remoteException = None
|
|
try:
|
|
exec 'remoteException = %s("%s")' % (exceptionClassName, message.response)
|
|
except Exception:
|
|
# We could not recreate the exception; create a generic one
|
|
remoteException = Exception(message.response)
|
|
df.errback(remoteException)
|
|
else:
|
|
# We got a result from the RPC
|
|
df.callback(message.response)
|
|
else:
|
|
# If the original message isn't found, it must have timed out
|
|
#TODO: we should probably do something with this...
|
|
pass
|
|
|
|
def _send(self, data, rpcID, address):
|
|
""" Transmit the specified data over UDP, breaking it up into several
|
|
packets if necessary
|
|
|
|
If the data is spread over multiple UDP datagrams, the packets have the
|
|
following structure::
|
|
| | | | | |||||||||||| 0x00 |
|
|
|Transmision|Total number|Sequence number| RPC ID |Header end|
|
|
| type ID | of packets |of this packet | | indicator|
|
|
| (1 byte) | (2 bytes) | (2 bytes) |(20 bytes)| (1 byte) |
|
|
| | | | | |||||||||||| |
|
|
|
|
@note: The header used for breaking up large data segments will
|
|
possibly be moved out of the KademliaProtocol class in the
|
|
future, into something similar to a message translator/encoder
|
|
class (see C{kademlia.msgformat} and C{kademlia.encoding}).
|
|
"""
|
|
if len(data) > self.msgSizeLimit:
|
|
# We have to spread the data over multiple UDP datagrams,
|
|
# and provide sequencing information
|
|
#
|
|
# 1st byte is transmission type id, bytes 2 & 3 are the
|
|
# total number of packets in this transmission, bytes 4 &
|
|
# 5 are the sequence number for this specific packet
|
|
totalPackets = len(data) / self.msgSizeLimit
|
|
if len(data) % self.msgSizeLimit > 0:
|
|
totalPackets += 1
|
|
encTotalPackets = chr(totalPackets >> 8) + chr(totalPackets & 0xff)
|
|
seqNumber = 0
|
|
startPos = 0
|
|
while seqNumber < totalPackets:
|
|
packetData = data[startPos:startPos+self.msgSizeLimit]
|
|
encSeqNumber = chr(seqNumber >> 8) + chr(seqNumber & 0xff)
|
|
txData = '\x00%s%s%s\x00%s' % (encTotalPackets, encSeqNumber, rpcID, packetData)
|
|
self._scheduleSendNext(txData, address)
|
|
|
|
startPos += self.msgSizeLimit
|
|
seqNumber += 1
|
|
else:
|
|
self._scheduleSendNext(data, address)
|
|
|
|
def _scheduleSendNext(self, txData, address):
|
|
"""Schedule the sending of the next UDP packet """
|
|
delay = self._delay()
|
|
key = object()
|
|
delayed_call = reactor.callLater(delay, self._write_and_remove, key, txData, address)
|
|
self._call_later_list[key] = delayed_call
|
|
|
|
def _write_and_remove(self, key, txData, address):
|
|
del self._call_later_list[key]
|
|
if self.transport:
|
|
self.transport.write(txData, address)
|
|
|
|
def _sendResponse(self, contact, rpcID, response):
|
|
""" Send a RPC response to the specified contact
|
|
"""
|
|
msg = msgtypes.ResponseMessage(rpcID, self._node.id, response)
|
|
msgPrimitive = self._translator.toPrimitive(msg)
|
|
encodedMsg = self._encoder.encode(msgPrimitive)
|
|
self._send(encodedMsg, rpcID, (contact.address, contact.port))
|
|
|
|
def _sendError(self, contact, rpcID, exceptionType, exceptionMessage):
|
|
""" Send an RPC error message to the specified contact
|
|
"""
|
|
msg = msgtypes.ErrorMessage(rpcID, self._node.id, exceptionType, exceptionMessage)
|
|
msgPrimitive = self._translator.toPrimitive(msg)
|
|
encodedMsg = self._encoder.encode(msgPrimitive)
|
|
self._send(encodedMsg, rpcID, (contact.address, contact.port))
|
|
|
|
def _handleRPC(self, senderContact, rpcID, method, args):
|
|
""" Executes a local function in response to an RPC request """
|
|
# Set up the deferred callchain
|
|
def handleError(f):
|
|
self._sendError(senderContact, rpcID, f.type, f.getErrorMessage())
|
|
|
|
def handleResult(result):
|
|
self._sendResponse(senderContact, rpcID, result)
|
|
|
|
df = defer.Deferred()
|
|
df.addCallback(handleResult)
|
|
df.addErrback(handleError)
|
|
|
|
# Execute the RPC
|
|
func = getattr(self._node, method, None)
|
|
if callable(func) and hasattr(func, 'rpcmethod'):
|
|
# Call the exposed Node method and return the result to the deferred callback chain
|
|
try:
|
|
kwargs = {'_rpcNodeID': senderContact.id, '_rpcNodeContact': senderContact}
|
|
result = func(*args, **kwargs)
|
|
except Exception, e:
|
|
df.errback(failure.Failure(e))
|
|
else:
|
|
df.callback(result)
|
|
else:
|
|
# No such exposed method
|
|
df.errback(failure.Failure(AttributeError('Invalid method: %s' % method)))
|
|
|
|
def _msgTimeout(self, messageID):
|
|
""" Called when an RPC request message times out """
|
|
# Find the message that timed out
|
|
if not self._sentMessages.has_key(messageID):
|
|
# This should never be reached
|
|
log.error("deferred timed out, but is not present in sent messages list!")
|
|
return
|
|
remoteContactID, df = self._sentMessages[messageID][0:2]
|
|
if self._partialMessages.has_key(messageID):
|
|
# We are still receiving this message
|
|
self._msgTimeoutInProgress(messageID, remoteContactID, df)
|
|
return
|
|
del self._sentMessages[messageID]
|
|
# The message's destination node is now considered to be dead;
|
|
# raise an (asynchronous) TimeoutError exception and update the host node
|
|
self._node.removeContact(remoteContactID)
|
|
df.errback(failure.Failure(TimeoutError(remoteContactID)))
|
|
|
|
def _msgTimeoutInProgress(self, messageID, remoteContactID, df):
|
|
# See if any progress has been made; if not, kill the message
|
|
if self._hasProgressBeenMade(messageID):
|
|
# Reset the RPC timeout timer
|
|
timeoutCall = reactor.callLater(constants.rpcTimeout, self._msgTimeout, messageID)
|
|
self._sentMessages[messageID] = (remoteContactID, df, timeoutCall)
|
|
else:
|
|
# No progress has been made
|
|
del self._partialMessagesProgress[messageID]
|
|
del self._partialMessages[messageID]
|
|
df.errback(failure.Failure(TimeoutError(remoteContactID)))
|
|
|
|
def _hasProgressBeenMade(self, messageID):
|
|
return (
|
|
self._partialMessagesProgress.has_key(messageID) and
|
|
(
|
|
len(self._partialMessagesProgress[messageID]) !=
|
|
len(self._partialMessages[messageID])
|
|
)
|
|
)
|
|
|
|
def stopProtocol(self):
|
|
""" Called when the transport is disconnected.
|
|
|
|
Will only be called once, after all ports are disconnected.
|
|
"""
|
|
log.info('Stopping dht')
|
|
for delayed_call in self._call_later_list.values():
|
|
try:
|
|
delayed_call.cancel()
|
|
except (error.AlreadyCalled, error.AlreadyCancelled):
|
|
log.debug('Attempted to cancel a DelayedCall that was not active')
|
|
except Exception:
|
|
log.exception('Failed to cancel a DelayedCall')
|
|
# not sure why this is needed, but taking this out sometimes causes
|
|
# exceptions.AttributeError: 'Port' object has no attribute 'socket'
|
|
# to happen on shutdown
|
|
# reactor.iterate()
|