import logging import time import socket import errno from twisted.internet import protocol, defer, error, reactor, task import constants import encoding import msgtypes import msgformat from contact import Contact from error import BUILTIN_EXCEPTIONS, UnknownRemoteException, TimeoutError from delay import Delay log = logging.getLogger(__name__) class KademliaProtocol(protocol.DatagramProtocol): """ Implements all low-level network-related functions of a Kademlia node """ msgSizeLimit = constants.udpDatagramMaxSize - 26 def __init__(self, node): self._node = node self._encoder = encoding.Bencode() self._translator = msgformat.DefaultFormat() 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 = {} # keep track of bandwidth usage by peer self._history_rx = {} self._history_tx = {} self._bytes_rx = {} self._bytes_tx = {} self._unique_contacts = [] self._queries_rx_per_second = 0 self._queries_tx_per_second = 0 self._kbps_tx = 0 self._kbps_rx = 0 self._recent_contact_count = 0 self._total_bytes_tx = 0 self._total_bytes_rx = 0 self._bandwidth_stats_update_lc = task.LoopingCall(self._update_bandwidth_stats) def _update_bandwidth_stats(self): recent_rx_history = {} now = time.time() for address, history in self._history_rx.iteritems(): recent_rx_history[address] = [(s, t) for (s, t) in history if now - t < 1.0] qps_rx = sum(len(v) for (k, v) in recent_rx_history.iteritems()) bps_rx = sum(sum([x[0] for x in v]) for (k, v) in recent_rx_history.iteritems()) kbps_rx = round(float(bps_rx) / 1024.0, 2) recent_tx_history = {} now = time.time() for address, history in self._history_tx.iteritems(): recent_tx_history[address] = [(s, t) for (s, t) in history if now - t < 1.0] qps_tx = sum(len(v) for (k, v) in recent_tx_history.iteritems()) bps_tx = sum(sum([x[0] for x in v]) for (k, v) in recent_tx_history.iteritems()) kbps_tx = round(float(bps_tx) / 1024.0, 2) recent_contacts = [] for k, v in recent_rx_history.iteritems(): if v: recent_contacts.append(k) for k, v in recent_tx_history.iteritems(): if v and k not in recent_contacts: recent_contacts.append(k) self._queries_rx_per_second = qps_rx self._queries_tx_per_second = qps_tx self._kbps_tx = kbps_tx self._kbps_rx = kbps_rx self._recent_contact_count = len(recent_contacts) self._total_bytes_tx = sum(v for (k, v) in self._bytes_tx.iteritems()) self._total_bytes_rx = sum(v for (k, v) in self._bytes_rx.iteritems()) @property def unique_contacts(self): return self._unique_contacts @property def queries_rx_per_second(self): return self._queries_rx_per_second @property def queries_tx_per_second(self): return self._queries_tx_per_second @property def kbps_tx(self): return self._kbps_tx @property def kbps_rx(self): return self._kbps_rx @property def recent_contact_count(self): return self._recent_contact_count @property def total_bytes_tx(self): return self._total_bytes_tx @property def total_bytes_rx(self): return self._total_bytes_rx @property def bandwidth_stats(self): response = { "kbps_received": self.kbps_rx, "kbps_sent": self.kbps_tx, "total_bytes_sent": self.total_bytes_tx, "total_bytes_received": self.total_bytes_rx, "queries_received": self.queries_rx_per_second, "queries_sent": self.queries_tx_per_second, "recent_contacts": self.recent_contact_count, "unique_contacts": len(self.unique_contacts) } return response 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.node_id, method, args) msgPrimitive = self._translator.toPrimitive(msg) encodedMsg = self._encoder.encode(msgPrimitive) if args: log.debug("DHT SEND CALL %s(%s)", method, args[0].encode('hex')) else: log.debug("DHT SEND CALL %s", method) df = defer.Deferred() if rawResponse: df._rpcRawResponse = True # Set the RPC timeout timer timeoutCall = reactor.callLater(constants.rpcTimeout, self._msgTimeout, msg.id) # Transmit the data self._send(encodedMsg, msg.id, (contact.address, contact.port)) self._sentMessages[msg.id] = (contact.id, df, timeoutCall, method, args) return df def startProtocol(self): log.info("DHT listening on UDP %i", self._node.port) if not self._bandwidth_stats_update_lc.running: self._bandwidth_stats_update_lc.start(1) 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) now = time.time() contact_history = self._history_rx.get(address, []) if len(contact_history) > 1000: contact_history = [x for x in contact_history if now - x[1] < 1.0] contact_history.append((len(datagram), time.time())) self._history_rx[address] = contact_history bytes_rx = self._bytes_rx.get(address, 0) bytes_rx += len(datagram) self._bytes_rx[address] = bytes_rx if address not in self.unique_contacts: self._unique_contacts.append(address) # 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 message.id in self._sentMessages: # 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 in BUILTIN_EXCEPTIONS: exception_type = BUILTIN_EXCEPTIONS[message.exceptionType] else: exception_type = UnknownRemoteException remoteException = exception_type(message.response) log.error("Remote exception (%s): %s", address, remoteException) 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}). """ now = time.time() contact_history = self._history_tx.get(address, []) if len(contact_history) > 1000: contact_history = [x for x in contact_history if now - x[1] < 1.0] contact_history.append((len(data), time.time())) self._history_tx[address] = contact_history bytes_tx = self._bytes_tx.get(address, 0) bytes_tx += len(data) self._bytes_tx[address] = bytes_tx if address not in self.unique_contacts: self._unique_contacts.append(address) 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: try: self.transport.write(txData, address) except socket.error as err: if err.errno == errno.EWOULDBLOCK: # i'm scared this may swallow important errors, but i get a million of these # on Linux and it doesnt seem to affect anything -grin log.debug("Can't send data to dht: EWOULDBLOCK") elif err.errno == errno.ENETUNREACH: # this should probably try to retransmit when the network connection is back log.error("Network is unreachable") else: log.error("DHT socket error: %s (%i)", err.message, err.errno) raise err def _sendResponse(self, contact, rpcID, response): """ Send a RPC response to the specified contact """ msg = msgtypes.ResponseMessage(rpcID, self._node.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.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 if args: log.debug("DHT RECV CALL %s(%s) %s:%i", method, args[0].encode('hex'), senderContact.address, senderContact.port) else: log.debug("DHT RECV CALL %s %s:%i", method, senderContact.address, senderContact.port) try: if method != 'ping': kwargs = {'_rpcNodeID': senderContact.id, '_rpcNodeContact': senderContact} result = func(*args, **kwargs) else: result = func() except Exception, e: log.exception("error handling request for %s: %s", senderContact.address, method) df.errback(e) else: df.callback(result) else: # No such exposed method df.errback(AttributeError('Invalid method: %s' % method)) def _msgTimeout(self, messageID): """ Called when an RPC request message times out """ # Find the message that timed out if messageID not in self._sentMessages: # This should never be reached log.error("deferred timed out, but is not present in sent messages list!") return remoteContactID, df, timeout_call, method, args = self._sentMessages[messageID] if self._partialMessages.has_key(messageID): # We are still receiving this message self._msgTimeoutInProgress(messageID, remoteContactID, df, method, args) 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(TimeoutError(remoteContactID)) def _msgTimeoutInProgress(self, messageID, remoteContactID, df, method, args): # 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, method, args) else: # No progress has been made del self._partialMessagesProgress[messageID] del self._partialMessages[messageID] df.errback(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') if self._bandwidth_stats_update_lc.running: self._bandwidth_stats_update_lc.stop() 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() log.info('DHT stopped')