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walkingonions-boosted/client.py
2022-03-17 17:05:34 +01:00

574 lines
23 KiB
Python

#!/usr/bin/env python3
import random # For simulation, not cryptography!
import math
import sys
import time
import logging
import network
import dirauth
import relay
import cell as simcell
import msg as simmsg
import nacl.hash
class VanillaCreatedExtendedHandler:
"""A handler for VanillaCreatedCircuitCell and
VanillaExtendedCircuitCell cells."""
def __init__(self, channelmgr, ntor, expecteddesc):
self.channelmgr = channelmgr
self.ntor = ntor
self.expecteddesc = expecteddesc
self.onionkey = expecteddesc.descdict['onionkey']
self.idkey = expecteddesc.descdict['idkey']
def received_cell(self, circhandler, cell):
secret = self.ntor.verify(cell.ntor_reply, self.onionkey, self.idkey)
enckey = nacl.hash.sha256(secret + b'upstream')
deckey = nacl.hash.sha256(secret + b'downstream')
circhandler.add_crypt_layer(enckey, deckey)
if len(circhandler.circuit_descs) == 0:
# This was a VanillaCreatedCircuitCell
circhandler.replace_celltype_handler(
simcell.VanillaCreatedCircuitCell, None)
else:
# This was a VanillaExtendedCircuitCell
circhandler.replace_celltype_handler(
simcell.VanillaExtendedCircuitCell, None)
circhandler.circuit_descs.append(self.expecteddesc)
# Are we done building the circuit?
if len(circhandler.circuit_descs) == 3:
# Yes!
return
nexthop = None
while nexthop is None:
nexthop = self.channelmgr.relaypicker.pick_weighted_relay()
if nexthop.descdict['addr'] in \
[ desc.descdict['addr'] \
for desc in circhandler.circuit_descs ]:
nexthop = None
# Construct the VanillaExtendCircuitCell
ntor = relay.NTor(self.channelmgr.perfstats)
ntor_request = ntor.request()
circextendmsg = simcell.VanillaExtendCircuitCell(
nexthop.descdict['addr'], ntor_request)
# Set up the reply handler
circhandler.replace_celltype_handler(
simcell.VanillaExtendedCircuitCell,
VanillaCreatedExtendedHandler(self.channelmgr, ntor, nexthop))
# Send the cell
circhandler.send_cell(circextendmsg)
class TelescopingCreatedHandler:
"""A handler for TelescopingCreatedCircuitCell cells; this will only always
communicate with the client's guard."""
def __init__(self, channelmgr, ntor):
self.channelmgr = channelmgr
self.ntor = ntor
if type(self.channelmgr.guard) is dirauth.RelayDescriptor:
guardd = self.channelmgr.guard.descdict
else:
guardd = self.channelmgr.guard.snipdict
self.onionkey = guardd["onionkey"]
self.idkey = guardd["idkey"]
def received_cell(self, circhandler, cell):
logging.debug("Received cell in TelescopingCreatedHandler")
secret = self.ntor.verify(cell.ntor_reply, self.onionkey, self.idkey)
enckey = nacl.hash.sha256(secret + b'upstream')
deckey = nacl.hash.sha256(secret + b'downstream')
circhandler.add_crypt_layer(enckey, deckey)
circhandler.replace_celltype_handler(simcell.TelescopingCreatedCircuitCell, None)
circhandler.circuit_descs.append(self.channelmgr.guard)
nexthopidx = None
while nexthopidx is None:
nexthopidx = self.channelmgr.relaypicker.pick_weighted_relay_index()
#print("WARNING: Unimplemented! Need to check if this idx is in the list of circhandlers idxs")
# TODO verify we don't need to do the above
# Construct the TelescopingExtendCircuitCell
ntor = relay.NTor(self.channelmgr.perfstats)
ntor_request = ntor.request()
circextendmsg = simcell.TelescopingExtendCircuitCell(
nexthopidx, ntor_request)
# Set up the reply handler
circhandler.replace_celltype_handler(
simcell.TelescopingExtendedCircuitCell,
TelescopingExtendedHandler(self.channelmgr, ntor))
# Send the cell
circhandler.send_cell(circextendmsg)
class TelescopingExtendedHandler:
"""A handler for TelescopingExtendedCircuitCell cells."""
def __init__(self, channelmgr, ntor):
self.channelmgr = channelmgr
self.ntor = ntor
def received_cell(self, circhandler, cell):
logging.debug("Received cell in TelescopingExtendedHandler")
# Validate the SNIP
dirauth.SNIP.verify(cell.snip, self.channelmgr.consensus,
network.thenetwork.dirauthkeys()[0],
self.channelmgr.perfstats)
onionkey = cell.snip.snipdict['onionkey']
idkey = cell.snip.snipdict['idkey']
secret = self.ntor.verify(cell.ntor_reply, onionkey, idkey)
enckey = nacl.hash.sha256(secret + b'upstream')
deckey = nacl.hash.sha256(secret + b'downstream')
circhandler.add_crypt_layer(enckey, deckey)
circhandler.replace_celltype_handler(
simcell.TelescopingExtendedCircuitCell, None)
circhandler.circuit_descs.append(cell.snip)
# Are we done building the circuit?
#logging.warning("we may need another circhandler structure for snips")
if len(circhandler.circuit_descs) == 3:
# Yes!
return
nexthopidx = self.channelmgr.relaypicker.pick_weighted_relay_index()
# Construct the VanillaExtendCircuitCell
ntor = relay.NTor(self.channelmgr.perfstats)
ntor_request = ntor.request()
circextendmsg = simcell.TelescopingExtendCircuitCell(
nexthopidx, ntor_request)
# Set up the reply handler
circhandler.replace_celltype_handler(
simcell.TelescopingExtendedCircuitCell,
TelescopingExtendedHandler(self.channelmgr, ntor))
# Send the cell
circhandler.send_cell(circextendmsg)
class SinglePassCreatedHandler:
"""A handler for SinglePassCreatedCircuitCell cells."""
def __init__(self, channelmgr, ntor, client_key):
self.channelmgr = channelmgr
self.ntor = ntor
self.client_key = client_key
def received_cell(self, circhandler, cell):
# We should only get one simcell.SinglePassCreatedCircuitCell per
# circuit
circhandler.replace_celltype_handler(simcell.SinglePassCreatedCircuitCell, None)
# The circuit always starts with the guard
circhandler.circuit_descs.append(self.channelmgr.guard)
# Process each layer of the message
blinding_keys = []
while cell is not None:
lasthop = circhandler.circuit_descs[-1]
if type(lasthop) is dirauth.RelayDescriptor:
lasthopd = lasthop.descdict
else:
lasthopd = lasthop.snipdict
onionkey = lasthopd["onionkey"]
idkey = lasthopd["idkey"]
pathselkey = lasthopd["pathselkey"]
if cell.enc is None:
secret = self.ntor.verify(cell.ntor_reply, onionkey, idkey)
enckey = nacl.hash.sha256(secret + b'upstream')
deckey = nacl.hash.sha256(secret + b'downstream')
circhandler.add_crypt_layer(enckey, deckey)
cell = None
else:
secret = self.ntor.verify(cell.ntor_reply, onionkey,
idkey, b'circuit')
enckey = nacl.hash.sha256(secret + b'upstream')
deckey = nacl.hash.sha256(secret + b'downstream')
createdkey = nacl.hash.sha256(secret + b'created')
circhandler.add_crypt_layer(enckey, deckey)
(snip, vrfout, nextlayer) = cell.enc.decrypt(createdkey)
# Check the signature on the SNIP
dirauth.SNIP.verify(snip, self.channelmgr.consensus,
network.thenetwork.dirauthkeys()[0],
self.channelmgr.perfstats)
# Compute the index, check the VRF, ensure the SNIP is
# the correct one
pathsel_rand, next_blindkey = relay.Sphinx.client(
self.client_key, blinding_keys,
onionkey, b'pathsel',
nextlayer is None, self.channelmgr.perfstats)
if nextlayer is not None:
blinding_keys.append(next_blindkey)
try:
index = int.from_bytes(relay.VRF.check_output(pathselkey,
pathsel_rand, vrfout,
self.channelmgr.perfstats)[:4],
'big', signed=False)
except ValueError as e:
circhandler.close()
raise ValueError(str(e.args) + str(lasthopd))
indexrange = snip.snipdict["range"]
if index < indexrange[0] or index >= indexrange[1]:
logging.error("Incorrect SNIP received")
circhandler.circuit_descs.append(snip)
cell = nextlayer
class ClientChannelManager(relay.ChannelManager):
"""The subclass of ChannelManager for clients."""
def __init__(self, myaddr, dirauthaddrs, perfstats):
super().__init__(myaddr, dirauthaddrs, perfstats)
self.guardaddr = None
self.guard = None
self.circuit_build_begin = 0
def get_consensus_from_fallbackrelay(self):
"""Download a fresh consensus from a random fallbackrelay."""
fb = network.thenetwork.getfallbackrelay()
logging.debug("Chose fallback %s", fb)
if network.thenetwork.womode == network.WOMode.VANILLA:
if self.consensus is not None and \
len(self.consensus.consdict['relays']) > 0:
self.send_msg(simmsg.RelayGetConsensusDiffMsg(), fb.netaddr)
else:
self.send_msg(simmsg.RelayGetConsensusMsg(), fb.netaddr)
else:
self.send_msg(simmsg.RelayGetConsensusMsg(), fb.netaddr)
def ensure_guard_vanilla(self):
"""Ensure that we have a channel to a guard (Vanilla Onion
Routing version)."""
while True:
if self.guardaddr is None:
# Pick a guard from the consensus
self.guard = self.relaypicker.pick_weighted_relay()
self.guardaddr = self.guard.descdict['addr']
self.test_guard_connection()
if self.guardaddr is not None:
break
logging.debug('chose guard=%s', self.guardaddr)
def test_guard_connection(self):
# Connect to the guard
try:
self.get_channel_to(self.guardaddr)
except network.NetNoServer:
# Our guard is gone
self.guardaddr = None
self.guard = None
def ensure_guard_walking_onions(self):
"""Ensure we have a channel to a guard (Walking Onions version).
For the first implementation, we assume an out-of-band mechanism
that just simply hands us a guard; we don't count the number of
operations or bandwidth as this operation in practice occurs
infrequently."""
while True:
if self.guardaddr is None:
#randomly sample a guard
#logging.warning("Unimplemented! guard should be selected from any relays.")
self.guard = self.relaypicker.pick_weighted_relay()
# here, we have a SNIP instead of a relay descriptor
self.guardaddr = self.guard.snipdict['addr']
self.test_guard_connection()
if self.guardaddr is not None:
break
# Ensure we have the current descriptor for the guard
# Note that self.guard may be a RelayDescriptor or a SNIP,
# depending on how we got it
if type(self.guard) is dirauth.RelayDescriptor:
guardepoch = self.guard.descdict["epoch"]
else:
guardepoch = self.guard.snipdict["epoch"]
if guardepoch != network.thenetwork.getepoch():
guardchannel = self.get_channel_to(self.guardaddr)
guardchannel.send_msg(simmsg.RelayGetDescMsg())
logging.debug('chose guard=%s', self.guardaddr)
def ensure_guard(self):
"""Ensure that we have a channel to a guard."""
if network.thenetwork.womode == network.WOMode.VANILLA:
self.ensure_guard_vanilla()
return
# At this point, we are either in Telescoping or Single-Pass mode
self.ensure_guard_walking_onions()
def new_circuit_vanilla(self):
"""Create a new circuit from this client. (Vanilla Onion Routing
version)"""
# Get our channel to the guard
guardchannel = self.get_channel_to(self.guardaddr)
# Allocate a new circuit id on it
circid, circhandler = guardchannel.new_circuit()
# Construct the VanillaCreateCircuitMsg
ntor = relay.NTor(self.perfstats)
ntor_request = ntor.request()
circcreatemsg = simmsg.VanillaCreateCircuitMsg(circid, ntor_request)
# Set up the reply handler
circhandler.replace_celltype_handler(
simcell.VanillaCreatedCircuitCell,
VanillaCreatedExtendedHandler(self, ntor, self.guard))
# Send the message
guardchannel.send_msg(circcreatemsg)
if guardchannel.is_circuit_open(circid):
self.perfstats.circuit_building_time = time.perf_counter() - self.circuit_build_begin
logging.debug("Client %s ended circuit building after %s", self.myaddr, str(self.perfstats.circuit_building_time))
return circhandler
def new_circuit_telescoping(self):
"""Create a new circuit from this client (Telescoping Walking Onions
version). If an error occurs and the circuit is deleted from the guard
channel, return None, otherwise, return the circuit handler."""
# Get our channel to the guard
guardchannel = self.get_channel_to(self.guardaddr)
# Allocate a new circuit id on it
circid, circhandler = guardchannel.new_circuit()
# Construct the TelescopingCreateCircuitMsg
ntor = relay.NTor(self.perfstats)
ntor_request = ntor.request()
circcreatemsg = simmsg.TelescopingCreateCircuitMsg(circid, ntor_request)
# Set up the reply handler
circhandler.replace_celltype_handler(
simcell.TelescopingCreatedCircuitCell,
TelescopingCreatedHandler(self, ntor))
# Send the message
guardchannel.send_msg(circcreatemsg)
# Check to make sure the circuit is open before sending it- if there
# was an error when establishing it, the circuit could already be
# closed.
if guardchannel.is_circuit_open(circid):
self.perfstats.circuit_building_time = time.perf_counter() - self.circuit_build_begin
logging.debug("Client %s ended circuit building after %s", self.myaddr, str(self.perfstats.circuit_building_time))
else:
logging.debug("Circuit was already closed, not sending bytes. circid: " + str(circid))
return None
guard = circhandler.circuit_descs[0]
if type(guard) is dirauth.RelayDescriptor:
guardd = guard.descdict
else:
guardd = guard.snipdict
if guardd["addr"] == circhandler.circuit_descs[2].snipdict["addr"]:
logging.debug("circuit in a loop")
circhandler.close()
circhandler = None
return circhandler
def new_circuit_singlepass(self):
"""Create a new circuit from this client (Single-Pass Walking Onions
version). If an error occurs and the circuit is deleted from the guard
channel, return None, otherwise, return the circuit handler."""
# Get our channel to the guard
guardchannel = self.get_channel_to(self.guardaddr)
# Allocate a new circuit id on it
circid, circhandler = guardchannel.new_circuit()
# first, create the path-selection key used for Sphinx
client_pathsel_key = nacl.public.PrivateKey.generate()
self.perfstats.keygens += 1
# Construct the SinglePassCreateCircuitMsg
ntor = relay.NTor(self.perfstats)
ntor_request = ntor.request()
circcreatemsg = simmsg.SinglePassCreateCircuitMsg(circid, ntor_request,
client_pathsel_key.public_key)
# Set up the reply handler
circhandler.replace_celltype_handler(
simcell.SinglePassCreatedCircuitCell,
SinglePassCreatedHandler(self, ntor, client_pathsel_key))
# Send the message
guardchannel.send_msg(circcreatemsg)
# Check to make sure the circuit is open before sending it- if there
# was an error when establishing it, the circuit could already be
# closed.
if guardchannel.is_circuit_open(circid):
self.perfstats.circuit_building_time = time.perf_counter() - self.circuit_build_begin
logging.debug("Client %s ended circuit building after %s", self.myaddr, str(self.perfstats.circuit_building_time))
else:
logging.debug("Circuit was already closed, not sending bytes. circid: " + str(circid))
return None
# In Single-Pass Walking Onions, we need to check whether the
# circuit got into a loop (guard equals exit); each node will
# refuse to extend to itself, so this is the only possible loop
# in a circuit of length 3
guard = circhandler.circuit_descs[0]
if type(guard) is dirauth.RelayDescriptor:
guardd = guard.descdict
else:
guardd = guard.snipdict
if guardd["addr"] == circhandler.circuit_descs[2].snipdict["addr"]:
logging.debug("circuit in a loop")
circhandler.close()
circhandler = None
return circhandler
def new_circuit(self):
"""Create a new circuit from this client."""
circhandler = None
# Start tracking the time for building a circuit
self.circuit_build_begin = time.perf_counter()
logging.debug("%s began circuit building after %s", self.myaddr, str(self.circuit_build_begin))
# If an error occured, circhandler will still be None, so we should
# try again.
while circhandler is None:
if network.thenetwork.womode == network.WOMode.VANILLA:
circhandler = self.new_circuit_vanilla()
elif network.thenetwork.womode == network.WOMode.TELESCOPING:
circhandler = self.new_circuit_telescoping()
elif network.thenetwork.womode == network.WOMode.SINGLEPASS:
circhandler = self.new_circuit_singlepass()
return circhandler
def received_msg(self, msg, peeraddr, channel):
"""Callback when a NetMsg not specific to a circuit is
received."""
logging.debug("Client %s received msg %s from %s" % (self.myaddr, msg, peeraddr))
if isinstance(msg, simmsg.RelayConsensusMsg) or \
isinstance(msg, simmsg.RelayConsensusDiffMsg):
self.relaypicker = dirauth.Consensus.verify(msg.consensus,
network.thenetwork.dirauthkeys(), self.perfstats)
self.consensus = msg.consensus
elif isinstance(msg, simmsg.RelayDescMsg):
dirauth.RelayDescriptor.verify(msg.desc, self.perfstats)
self.guard = msg.desc
else:
return super().received_msg(msg, peeraddr, channel)
def received_cell(self, circid, cell, peeraddr, channel):
"""Callback with a circuit-specific cell is received."""
logging.debug("Client %s received cell on circ %d: %s from %s" % (self.myaddr, circid, cell, peeraddr))
if isinstance(cell, simcell.CloseCell):
logging.debug("Log: Client received close cell; closing circuit")
# TODO close cell
return super().received_cell(circid, cell, peeraddr, channel)
class Client:
"""A class representing a Tor client."""
def __init__(self, dirauthaddrs):
# Get a network address for client-side use only (do not bind it
# to the network)
self.netaddr = network.NetAddr()
self.perfstats = network.PerfStats(network.EntType.CLIENT)
self.perfstats.name = "Client at %s" % self.netaddr
self.perfstats.is_bootstrapping = True
self.channelmgr = ClientChannelManager(self.netaddr, dirauthaddrs,
self.perfstats)
# Register for epoch tick notifications
network.thenetwork.wantepochticks(self, True)
def terminate(self):
"""Quit this client."""
# Stop listening for epoch ticks
network.thenetwork.wantepochticks(self, False)
# Close relay connections
self.channelmgr.terminate()
def get_consensus(self):
"""Fetch a new consensus."""
# We're going to want a new consensus from our guard. In order
# to get that, we'll need a channel to our guard. In order to
# get that, we'll need a guard address. In order to get that,
# we'll need a consensus (uh, oh; in that case, fetch the
# consensus from a fallback relay).
guardaddr = self.channelmgr.guardaddr
guardchannel = None
if guardaddr is not None:
try:
guardchannel = self.channelmgr.get_channel_to(guardaddr)
except network.NetNoServer:
guardaddr = None
if guardchannel is None:
logging.debug("In bootstrapping mode")
self.channelmgr.get_consensus_from_fallbackrelay()
logging.debug('client consensus=%s', self.channelmgr.consensus)
return
if network.thenetwork.womode == network.WOMode.VANILLA:
if self.channelmgr.consensus is not None and len(self.channelmgr.consensus.consdict['relays']) > 0:
guardchannel.send_msg(simmsg.RelayGetConsensusDiffMsg())
logging.debug('got consensus diff, client consensus=%s', self.channelmgr.consensus)
return
# At this point, we are in one of the following scenarios:
# 1. This is a walking onions protocol, and the client fetches the
# complete consensus each epoch
# 2. This is Vanilla Onion Routing and the client doesn't have a
# consensus and needs to bootstrap it.
guardchannel.send_msg(simmsg.RelayGetConsensusMsg())
logging.debug('client consensus=%s', self.channelmgr.consensus)
def newepoch(self, epoch):
"""Callback that fires at the start of each epoch"""
# We'll need a new consensus
self.get_consensus()
# If we don't have a guard, pick one and make a channel to it
self.channelmgr.ensure_guard()