Reference client for Bitmessage: a P2P encrypted decentralised communication protocol:
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"""
BMObject and it's exceptions.
"""
import logging
import time
import protocol
import state
from addresses import calculateInventoryHash
from inventory import Inventory
from network.dandelion import Dandelion
logger = logging.getLogger('default')
class BMObjectInsufficientPOWError(Exception):
"""Exception indicating the object doesn't have sufficient proof of work."""
errorCodes = ("Insufficient proof of work")
class BMObjectInvalidDataError(Exception):
"""Exception indicating the data being parsed does not match the specification."""
errorCodes = ("Data invalid")
class BMObjectExpiredError(Exception):
"""Exception indicating the object's lifetime has expired."""
errorCodes = ("Object expired")
class BMObjectUnwantedStreamError(Exception):
"""Exception indicating the object is in a stream we didn't advertise as being interested in."""
errorCodes = ("Object in unwanted stream")
class BMObjectInvalidError(Exception):
"""The object's data does not match object specification."""
errorCodes = ("Invalid object")
class BMObjectAlreadyHaveError(Exception):
"""We received a duplicate object (one we already have)"""
errorCodes = ("Already have this object")
class BMObject(object):
"""Bitmessage Object as a class."""
# pylint: disable=too-many-instance-attributes
# max TTL, 28 days and 3 hours
maxTTL = 28 * 24 * 60 * 60 + 10800
# min TTL, 3 hour (in the past
minTTL = -3600
def __init__(
self,
nonce,
expiresTime,
objectType,
version,
streamNumber,
data,
payloadOffset
): # pylint: disable=too-many-arguments
self.nonce = nonce
self.expiresTime = expiresTime
self.objectType = objectType
self.version = version
self.streamNumber = streamNumber
self.inventoryHash = calculateInventoryHash(data)
# copy to avoid memory issues
self.data = bytearray(data)
self.tag = self.data[payloadOffset:payloadOffset + 32]
def checkProofOfWorkSufficient(self):
"""Perform a proof of work check for sufficiency."""
# Let us check to make sure that the proof of work is sufficient.
if not protocol.isProofOfWorkSufficient(self.data):
logger.info('Proof of work is insufficient.')
raise BMObjectInsufficientPOWError()
def checkEOLSanity(self):
"""Check if object's lifetime isn't ridiculously far in the past or future."""
# EOL sanity check
if self.expiresTime - int(time.time()) > BMObject.maxTTL:
logger.info(
'This object\'s End of Life time is too far in the future. Ignoring it. Time is %i',
self.expiresTime)
# .. todo:: remove from download queue
raise BMObjectExpiredError()
if self.expiresTime - int(time.time()) < BMObject.minTTL:
logger.info(
'This object\'s End of Life time was too long ago. Ignoring the object. Time is %i',
self.expiresTime)
# .. todo:: remove from download queue
raise BMObjectExpiredError()
def checkStream(self):
"""Check if object's stream matches streams we are interested in"""
if self.streamNumber not in state.streamsInWhichIAmParticipating:
logger.debug('The streamNumber %i isn\'t one we are interested in.', self.streamNumber)
raise BMObjectUnwantedStreamError()
def checkAlreadyHave(self):
"""
Check if we already have the object (so that we don't duplicate it in inventory or advertise it unnecessarily)
"""
# if it's a stem duplicate, pretend we don't have it
if Dandelion().hasHash(self.inventoryHash):
return
if self.inventoryHash in Inventory():
raise BMObjectAlreadyHaveError()
def checkObjectByType(self):
"""Call a object type specific check (objects can have additional checks based on their types)"""
if self.objectType == protocol.OBJECT_GETPUBKEY:
self.checkGetpubkey()
elif self.objectType == protocol.OBJECT_PUBKEY:
self.checkPubkey()
elif self.objectType == protocol.OBJECT_MSG:
self.checkMessage()
elif self.objectType == protocol.OBJECT_BROADCAST:
self.checkBroadcast()
# other objects don't require other types of tests
def checkMessage(self):
""""Message" object type checks."""
# pylint: disable=no-self-use
return
def checkGetpubkey(self):
""""Getpubkey" object type checks."""
if len(self.data) < 42:
logger.info('getpubkey message doesn\'t contain enough data. Ignoring.')
raise BMObjectInvalidError()
def checkPubkey(self):
""""Pubkey" object type checks."""
if len(self.data) < 146 or len(self.data) > 440: # sanity check
logger.info('pubkey object too short or too long. Ignoring.')
raise BMObjectInvalidError()
def checkBroadcast(self):
""""Broadcast" object type checks."""
if len(self.data) < 180:
logger.debug(
'The payload length of this broadcast packet is unreasonably low.'
' Someone is probably trying funny business. Ignoring message.')
raise BMObjectInvalidError()
# this isn't supported anymore
if self.version < 2:
raise BMObjectInvalidError()