PyBitmessage/src/network/bmproto.py

import base64
import hashlib
import random
import socket
import struct
import time

from bmconfigparser import BMConfigParser
from debug import logger
from inventory import Inventory
import knownnodes
from network.advanceddispatcher import AdvancedDispatcher
from network.dandelion import Dandelion
from network.bmobject import BMObject, BMObjectInsufficientPOWError, BMObjectInvalidDataError, \
        BMObjectExpiredError, BMObjectUnwantedStreamError, BMObjectInvalidError, BMObjectAlreadyHaveError
import network.connectionpool
from network.node import Node
from network.objectracker import ObjectTracker
from network.proxy import Proxy, ProxyError, GeneralProxyError

import addresses
from queues import objectProcessorQueue, portCheckerQueue, invQueue, addrQueue
import shared
import state
import protocol

class BMProtoError(ProxyError):
    errorCodes = ("Protocol error")


class BMProtoInsufficientDataError(BMProtoError):
    errorCodes = ("Insufficient data")


class BMProtoExcessiveDataError(BMProtoError):
    errorCodes = ("Too much data")


class BMProto(AdvancedDispatcher, ObjectTracker):
    # ~1.6 MB which is the maximum possible size of an inv message.
    maxMessageSize = 1600100
    # 2**18 = 256kB is the maximum size of an object payload
    maxObjectPayloadSize = 2**18
    # protocol specification says max 1000 addresses in one addr command
    maxAddrCount = 1000
    # protocol specification says max 50000 objects in one inv command
    maxObjectCount = 50000
    # address is online if online less than this many seconds ago
    addressAlive = 10800
    # maximum time offset
    maxTimeOffset = 3600

    def __init__(self, address=None, sock=None):
        AdvancedDispatcher.__init__(self, sock)
        self.isOutbound = False
        # packet/connection from a local IP
        self.local = False

    def bm_proto_reset(self):
        self.magic = None
        self.command = None
        self.payloadLength = 0
        self.checksum = None
        self.payload = None
        self.invalid = False
        self.payloadOffset = 0
        self.expectBytes = protocol.Header.size
        self.object = None
        self.dandelionRoutes = []
        self.dandelionRefresh = 0

    def state_bm_header(self):
        self.magic, self.command, self.payloadLength, self.checksum = protocol.Header.unpack(self.read_buf[:protocol.Header.size])
        self.command = self.command.rstrip('\x00')
        if self.magic != 0xE9BEB4D9:
            # skip 1 byte in order to sync
            self.set_state("bm_header", length=1)
            self.bm_proto_reset()
            logger.debug("Bad magic")
            if self.socket.type == socket.SOCK_STREAM:
                self.close_reason = "Bad magic"
                self.set_state("close")
            return False
        if self.payloadLength > BMProto.maxMessageSize:
            self.invalid = True
        self.set_state("bm_command", length=protocol.Header.size, expectBytes=self.payloadLength)
        return True
        
    def state_bm_command(self):
        self.payload = self.read_buf[:self.payloadLength]
        if self.checksum != hashlib.sha512(self.payload).digest()[0:4]:
            logger.debug("Bad checksum, ignoring")
            self.invalid = True
        retval = True
        if not self.fullyEstablished and self.command not in ("error", "version", "verack"):
            logger.error("Received command %s before connection was fully established, ignoring", self.command)
            self.invalid = True
        if not self.invalid:
            try:
                retval = getattr(self, "bm_command_" + str(self.command).lower())()
            except AttributeError:
                # unimplemented command
                logger.debug("unimplemented command %s", self.command)
            except BMProtoInsufficientDataError:
                logger.debug("packet length too short, skipping")
            except BMProtoExcessiveDataError:
                logger.debug("too much data, skipping")
            except BMObjectInsufficientPOWError:
                logger.debug("insufficient PoW, skipping")
            except BMObjectInvalidDataError:
                logger.debug("object invalid data, skipping")
            except BMObjectExpiredError:
                logger.debug("object expired, skipping")
            except BMObjectUnwantedStreamError:
                logger.debug("object not in wanted stream, skipping")
            except BMObjectInvalidError:
                logger.debug("object invalid, skipping")
            except BMObjectAlreadyHaveError:
                logger.debug("%s:%i already got object, skipping", self.destination.host, self.destination.port)
            except struct.error:
                logger.debug("decoding error, skipping")
        elif self.socket.type == socket.SOCK_DGRAM:
            # broken read, ignore
            pass
        else:
            #print "Skipping command %s due to invalid data" % (self.command)
            logger.debug("Closing due to invalid command %s", self.command)
            self.close_reason = "Invalid command %s" % (self.command)
            self.set_state("close")
            return False
        if retval:
            self.set_state("bm_header", length=self.payloadLength)
            self.bm_proto_reset()
        # else assume the command requires a different state to follow
        return True

    def decode_payload_string(self, length):
        value = self.payload[self.payloadOffset:self.payloadOffset+length]
        self.payloadOffset += length
        return value

    def decode_payload_varint(self):
        value, offset = addresses.decodeVarint(self.payload[self.payloadOffset:])
        self.payloadOffset += offset
        return value

    def decode_payload_node(self):
        services, host, port = self.decode_payload_content("Q16sH")
        if host[0:12] == '\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xFF\xFF':
            host = socket.inet_ntop(socket.AF_INET, str(host[12:16]))
        elif host[0:6] == '\xfd\x87\xd8\x7e\xeb\x43':
            # Onion, based on BMD/bitcoind
            host = base64.b32encode(host[6:]).lower() + ".onion"
        else:
            host = socket.inet_ntop(socket.AF_INET6, str(host))
        if host == "":
            # This can happen on Windows systems which are not 64-bit compatible 
            # so let us drop the IPv6 address. 
            host = socket.inet_ntop(socket.AF_INET, str(host[12:16]))

        return Node(services, host, port)

    def decode_payload_content(self, pattern = "v"):
        # L = varint indicating the length of the next array
        # l = varint indicating the length of the next item
        # v = varint (or array)
        # H = uint16
        # I = uint32
        # Q = uint64
        # i = net_addr (without time and stream number)
        # s = string
        # 0-9 = length of the next item
        # , = end of array

        def decode_simple(self, char="v"):
            if char == "v":
                return self.decode_payload_varint()
            if char == "i":
                return self.decode_payload_node()
            if char == "H":
                self.payloadOffset += 2
                return struct.unpack(">H", self.payload[self.payloadOffset-2:self.payloadOffset])[0]
            if char == "I":
                self.payloadOffset += 4
                return struct.unpack(">I", self.payload[self.payloadOffset-4:self.payloadOffset])[0]
            if char == "Q":
                self.payloadOffset += 8
                return struct.unpack(">Q", self.payload[self.payloadOffset-8:self.payloadOffset])[0]

        size = None
        isArray = False

        # size
        # iterator starting from size counting to 0
        # isArray?
        # subpattern
        # position of parser in subpattern
        # retval (array)
        parserStack = [[1, 1, False, pattern, 0, []]]

        #try:
        #    sys._getframe(200)
        #    logger.error("Stack depth warning, pattern: %s", pattern)
        #    return
        #except ValueError:
        #    pass

        while True:
            i = parserStack[-1][3][parserStack[-1][4]]
            if i in "0123456789" and (size is None or parserStack[-1][3][parserStack[-1][4]-1] not in "lL"):
                try:
                    size = size * 10 + int(i)
                except TypeError:
                    size = int(i)
                isArray = False
            elif i in "Ll" and size is None:
                size = self.decode_payload_varint()
                if i == "L":
                    isArray = True
                else:
                    isArray = False
            elif size is not None:
                if isArray:
                    parserStack.append([size, size, isArray, parserStack[-1][3][parserStack[-1][4]:], 0, []])
                    parserStack[-2][4] = len(parserStack[-2][3])
                else:
                    for j in range(parserStack[-1][4], len(parserStack[-1][3])):
                        if parserStack[-1][3][j] not in "lL0123456789":
                            break
                    parserStack.append([size, size, isArray, parserStack[-1][3][parserStack[-1][4]:j+1], 0, []])
                    parserStack[-2][4] += len(parserStack[-1][3]) - 1
                size = None
                continue
            elif i == "s":
                #if parserStack[-2][2]:
                #    parserStack[-1][5].append(self.payload[self.payloadOffset:self.payloadOffset + parserStack[-1][0]])
                #else:
                parserStack[-1][5] = self.payload[self.payloadOffset:self.payloadOffset + parserStack[-1][0]]
                self.payloadOffset += parserStack[-1][0]
                parserStack[-1][1] = 0
                parserStack[-1][2] = True
                #del parserStack[-1]
                size = None
            elif i in "viHIQ":
                parserStack[-1][5].append(decode_simple(self, parserStack[-1][3][parserStack[-1][4]]))
                size = None
            else:
                size = None
            for depth in range(len(parserStack) - 1, -1, -1):
                parserStack[depth][4] += 1
                if parserStack[depth][4] >= len(parserStack[depth][3]):
                    parserStack[depth][1] -= 1
                    parserStack[depth][4] = 0
                    if depth > 0:
                        if parserStack[depth][2]:
                            parserStack[depth - 1][5].append(parserStack[depth][5])
                        else:
                            parserStack[depth - 1][5].extend(parserStack[depth][5])
                        parserStack[depth][5] = []
                    if parserStack[depth][1] <= 0:
                        if depth == 0:
                            # we're done, at depth 0 counter is at 0 and pattern is done parsing
                            return parserStack[depth][5]
                        del parserStack[-1]
                        continue
                    break
                break
        if self.payloadOffset > self.payloadLength:
            logger.debug("Insufficient data %i/%i", self.payloadOffset, self.payloadLength)
            raise BMProtoInsufficientDataError()

    def bm_command_error(self):
        fatalStatus, banTime, inventoryVector, errorText = self.decode_payload_content("vvlsls")
        logger.error("%s:%i error: %i, %s", self.destination.host, self.destination.port, fatalStatus, errorText)
        return True

    def bm_command_getdata(self):
        items = self.decode_payload_content("l32s")
        # skip?
        if time.time() < self.skipUntil:
            return True
        #TODO make this more asynchronous
        random.shuffle(items)
        for i in map(str, items):
            if i in Dandelion().hashMap and \
                    self != Dandelion().hashMap[i]:
                self.antiIntersectionDelay()
                logger.info('%s asked for a stem object we didn\'t offer to it.', self.destination)
                break
            else:
                try:
                    self.append_write_buf(protocol.CreatePacket('object', Inventory()[i].payload))
                except KeyError:
                    self.antiIntersectionDelay()
                    logger.info('%s asked for an object we don\'t have.', self.destination)
                    break
        # I think that aborting after the first missing/stem object is more secure
        # when using random reordering, as the recipient won't know exactly which objects we refuse to deliver
        return True

    def bm_command_inv(self):
        items = self.decode_payload_content("l32s")

        if len(items) >= BMProto.maxObjectCount:
            logger.error("Too many items in inv message!")
            raise BMProtoExcessiveDataError()
        else:
            pass

        for i in map(str, items):
            self.handleReceivedInventory(i)

        return True

    def bm_command_dinv(self):
        """
        Dandelion stem announce
        """
        items = self.decode_payload_content("l32s")

        if len(items) >= BMProto.maxObjectCount:
            logger.error("Too many items in dinv message!")
            raise BMProtoExcessiveDataError()
        else:
            pass

        # ignore command if dandelion turned off
        if BMConfigParser().safeGetBoolean("network", "dandelion") == 0:
            return True

        for i in map(str, items):
            self.handleReceivedInventory(i)
            Dandelion().addHash(i, self)

        return True

    def bm_command_object(self):
        objectOffset = self.payloadOffset
        nonce, expiresTime, objectType, version, streamNumber = self.decode_payload_content("QQIvv")
        self.object = BMObject(nonce, expiresTime, objectType, version, streamNumber, self.payload, self.payloadOffset)

        if len(self.payload) - self.payloadOffset > BMProto.maxObjectPayloadSize:
            logger.info('The payload length of this object is too large (%s bytes). Ignoring it.' % len(self.payload) - self.payloadOffset)
            raise BMProtoExcessiveDataError()

        try:
            self.object.checkProofOfWorkSufficient()
            self.object.checkEOLSanity()
            self.object.checkAlreadyHave()
        except (BMObjectExpiredError, BMObjectAlreadyHaveError, BMObjectInsufficientPOWError) as e:
            BMProto.stopDownloadingObject(self.object.inventoryHash)
            raise e
        try:
            self.object.checkStream()
        except (BMObjectUnwantedStreamError,) as e:
            BMProto.stopDownloadingObject(self.object.inventoryHash, BMConfigParser().get("inventory", "acceptmismatch"))
            if not BMConfigParser().get("inventory", "acceptmismatch"):
                raise e

        try:
            self.object.checkObjectByType()
            objectProcessorQueue.put((self.object.objectType, buffer(self.object.data)))
        except BMObjectInvalidError as e:
            BMProto.stopDownloadingObject(self.object.inventoryHash, True)
        else:
            try:
                del state.missingObjects[self.object.inventoryHash]
            except KeyError:
                pass

        Inventory()[self.object.inventoryHash] = (
                self.object.objectType, self.object.streamNumber, buffer(self.payload[objectOffset:]), self.object.expiresTime, buffer(self.object.tag))
        invQueue.put((self.object.streamNumber, self.object.inventoryHash, self.destination))
        return True

    def _decode_addr(self):
        return self.decode_payload_content("LQIQ16sH")

    def bm_command_addr(self):
        addresses = self._decode_addr()
        for i in addresses:
            seenTime, stream, services, ip, port = i
            decodedIP = protocol.checkIPAddress(str(ip))
            if stream not in state.streamsInWhichIAmParticipating:
                continue
            if decodedIP is not False and seenTime > time.time() - BMProto.addressAlive:
                peer = state.Peer(decodedIP, port)
                try:
                    if knownnodes.knownNodes[stream][peer]["lastseen"] > seenTime:
                        continue
                except KeyError:
                    pass
                if len(knownnodes.knownNodes[stream]) < int(BMConfigParser().get("knownnodes", "maxnodes")):
                    with knownnodes.knownNodesLock:
                        try:
                            knownnodes.knownNodes[stream][peer]["lastseen"] = seenTime
                        except (TypeError, KeyError):
                            knownnodes.knownNodes[stream][peer] = {
                                "lastseen": seenTime,
                                "rating": 0,
                                "self": False,
                            }
                addrQueue.put((stream, peer, self.destination))
        return True

    def bm_command_portcheck(self):
        portCheckerQueue.put(state.Peer(self.destination, self.peerNode.port))
        return True

    def bm_command_ping(self):
        self.append_write_buf(protocol.CreatePacket('pong'))
        return True

    def bm_command_pong(self):
        # nothing really
        return True

    def bm_command_verack(self):
        self.verackReceived = True
        if self.verackSent:
            if self.isSSL:
                self.set_state("tls_init", length=self.payloadLength, expectBytes=0)
                return False
            self.set_state("connection_fully_established", length=self.payloadLength, expectBytes=0)
            return False
        return True

    def bm_command_version(self):
        self.remoteProtocolVersion, self.services, self.timestamp, self.sockNode, self.peerNode, self.nonce, \
            self.userAgent, self.streams = self.decode_payload_content("IQQiiQlsLv")
        self.nonce = struct.pack('>Q', self.nonce)
        self.timeOffset = self.timestamp - int(time.time())
        logger.debug("remoteProtocolVersion: %i", self.remoteProtocolVersion)
        logger.debug("services: 0x%08X", self.services)
        logger.debug("time offset: %i", self.timestamp - int(time.time()))
        logger.debug("my external IP: %s", self.sockNode.host)
        logger.debug("remote node incoming address: %s:%i", self.destination.host, self.peerNode.port)
        logger.debug("user agent: %s", self.userAgent)
        logger.debug("streams: [%s]", ",".join(map(str,self.streams)))
        if not self.peerValidityChecks():
            # TODO ABORT
            return True
        #shared.connectedHostsList[self.destination] = self.streams[0]
        self.append_write_buf(protocol.CreatePacket('verack'))
        self.verackSent = True
        if not self.isOutbound:
            self.append_write_buf(protocol.assembleVersionMessage(self.destination.host, self.destination.port, \
                    network.connectionpool.BMConnectionPool().streams, True, nodeid=self.nodeid))
            #print "%s:%i: Sending version"  % (self.destination.host, self.destination.port)
        if ((self.services & protocol.NODE_SSL == protocol.NODE_SSL) and
                protocol.haveSSL(not self.isOutbound)):
            self.isSSL = True
        if self.verackReceived:
            if self.isSSL:
                self.set_state("tls_init", length=self.payloadLength, expectBytes=0)
                return False
            self.set_state("connection_fully_established", length=self.payloadLength, expectBytes=0)
            return False
        return True

    def peerValidityChecks(self):
        if self.remoteProtocolVersion < 3:
            self.append_write_buf(protocol.assembleErrorMessage(fatal=2,
                errorText="Your is using an old protocol. Closing connection."))
            logger.debug ('Closing connection to old protocol version %s, node: %s',
                str(self.remoteProtocolVersion), str(self.destination))
            return False
        if self.timeOffset > BMProto.maxTimeOffset:
            self.append_write_buf(protocol.assembleErrorMessage(fatal=2,
                errorText="Your time is too far in the future compared to mine. Closing connection."))
            logger.info("%s's time is too far in the future (%s seconds). Closing connection to it.",
                self.destination, self.timeOffset)
            shared.timeOffsetWrongCount += 1
            return False
        elif self.timeOffset < -BMProto.maxTimeOffset:
            self.append_write_buf(protocol.assembleErrorMessage(fatal=2,
                errorText="Your time is too far in the past compared to mine. Closing connection."))
            logger.info("%s's time is too far in the past (timeOffset %s seconds). Closing connection to it.",
                self.destination, self.timeOffset)
            shared.timeOffsetWrongCount += 1
            return False
        else:
            shared.timeOffsetWrongCount = 0
        if not self.streams:
            self.append_write_buf(protocol.assembleErrorMessage(fatal=2,
                errorText="We don't have shared stream interests. Closing connection."))
            logger.debug ('Closed connection to %s because there is no overlapping interest in streams.',
                str(self.destination))
            return False
        if self.destination in network.connectionpool.BMConnectionPool().inboundConnections:
            try:
                if not protocol.checkSocksIP(self.destination.host):
                    self.append_write_buf(protocol.assembleErrorMessage(fatal=2,
                        errorText="Too many connections from your IP. Closing connection."))
                    logger.debug ('Closed connection to %s because we are already connected to that IP.',
                        str(self.destination))
                    return False
            except:
                pass
        if not self.isOutbound:
            # incoming from a peer we're connected to as outbound, or server full
            # report the same error to counter deanonymisation
            if state.Peer(self.destination.host, self.peerNode.port) in \
                network.connectionpool.BMConnectionPool().inboundConnections or \
                len(network.connectionpool.BMConnectionPool().inboundConnections) + \
                len(network.connectionpool.BMConnectionPool().outboundConnections) > \
                BMConfigParser().safeGetInt("bitmessagesettings", "maxtotalconnections") + \
                BMConfigParser().safeGetInt("bitmessagesettings", "maxbootstrapconnections"):
                self.append_write_buf(protocol.assembleErrorMessage(fatal=2,
                    errorText="Server full, please try again later."))
                logger.debug ("Closed connection to %s due to server full or duplicate inbound/outbound.",
                    str(self.destination))
                return False
        if network.connectionpool.BMConnectionPool().isAlreadyConnected(self.nonce):
            self.append_write_buf(protocol.assembleErrorMessage(fatal=2,
                errorText="I'm connected to myself. Closing connection."))
            logger.debug ("Closed connection to %s because I'm connected to myself.",
                str(self.destination))
            return False

        return True

    @staticmethod
    def assembleAddr(peerList):
        if isinstance(peerList, state.Peer):
            peerList = (peerList)
        if not peerList:
            return b''
        retval = b''
        for i in range(0, len(peerList), BMProto.maxAddrCount):
            payload = addresses.encodeVarint(len(peerList[i:i + BMProto.maxAddrCount]))
            for address in peerList[i:i + BMProto.maxAddrCount]:
                stream, peer, timestamp = address
                payload += struct.pack(
                    '>Q', timestamp)  # 64-bit time
                payload += struct.pack('>I', stream)
                payload += struct.pack(
                    '>q', 1)  # service bit flags offered by this node
                payload += protocol.encodeHost(peer.host)
                payload += struct.pack('>H', peer.port)  # remote port
            retval += protocol.CreatePacket('addr', payload)
        return retval

    @staticmethod
    def stopDownloadingObject(hashId, forwardAnyway=False):
        for connection in network.connectionpool.BMConnectionPool().inboundConnections.values() + \
                network.connectionpool.BMConnectionPool().outboundConnections.values():
            try:
                del connection.objectsNewToMe[hashId]
            except KeyError:
                pass
            if not forwardAnyway:
                try:
                    with connection.objectsNewToThemLock:
                        del connection.objectsNewToThem[hashId]
                except KeyError:
                    pass
        try:
            del state.missingObjects[hashId]
        except KeyError:
            pass

    def handle_close(self):
        self.set_state("close")
        if not (self.accepting or self.connecting or self.connected):
            # already disconnected
            return
        try:
            logger.debug("%s:%i: closing, %s", self.destination.host, self.destination.port, self.close_reason)
        except AttributeError:
            try:
                logger.debug("%s:%i: closing", self.destination.host, self.destination.port)
            except AttributeError:
                logger.debug("Disconnected socket closing")
        AdvancedDispatcher.handle_close(self)