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

1037 lines
45 KiB
Python

#!/usr/bin/env python3
import os
import random # For simulation, not cryptography!
import math
import sys
import logging
import resource
import nacl.utils
import nacl.signing
import nacl.public
import nacl.hash
import nacl.bindings
import network
import dirauth
import msg as simmsg
import cell as simcell
from connection import Connection
vrftable = dict()
# Simulated VRF. The output and proof are of the correct size (32 bytes
# for the output, 48 bytes for the proof), and we charge the right
# number of group operations (1 keygen, 2 DH for proving, 3 DH for
# verifiying -- that last number charges 1 DH for a (s*G+c*Y) multiexp,
# but 2 for a (s*A+c*B) multiexp)
class VRF:
@staticmethod
def get_output(vrf_privkey, vrf_input, perfstats):
"""Given the VRF private key and the input, produce
the output value and the proof."""
# nacl can't do the group operations we need to actually
# compute the VRF, so we just fake it for the simulation. The
# output value is sha256(privkey, input), and the proof is
# sha256(pubkey, input, output) + 16 bytes of 0.
# ***THIS IS NOT A REAL VRF!***
val = nacl.hash.sha256(bytes(vrf_privkey) + vrf_input,
encoder=nacl.encoding.RawEncoder)
vrf_pubkey = vrf_privkey.public_key
proof = nacl.hash.sha256(bytes(vrf_pubkey) + val + vrf_input,
encoder=nacl.encoding.RawEncoder) + bytes(16)
perfstats.keygens += 1
perfstats.dhs += 2
vrftable[proof] = (bytes(vrf_privkey), vrf_input, val, bytes(vrf_pubkey))
return val, proof
@staticmethod
def check_output(vrf_pubkey, vrf_input, vrf_output, perfstats):
"""Given the VRF public key, the input, and the claimed output
and proof, raise an exception if the proof fails to check.
Returns the VRF output."""
# Again, NOT A REAL VRF!
val, proof = vrf_output
if nacl.hash.sha256(vrf_pubkey + val + vrf_input,
encoder=nacl.encoding.RawEncoder) + bytes(16) != \
proof:
t = [nacl.encoding.HexEncoder.encode(x) for x in vrftable[proof]]
raise ValueError("VRF proof did not verify: %s %s %s 00x16 ?= %s: %s" % \
(nacl.encoding.HexEncoder.encode(vrf_pubkey),
nacl.encoding.HexEncoder.encode(val),
nacl.encoding.HexEncoder.encode(vrf_input),
nacl.encoding.HexEncoder.encode(proof),
t))
perfstats.dhs += 3
del vrftable[proof]
return val
class RelayFallbackTerminationError(Exception):
"""An exception raised when someone tries to terminate a fallback
relay."""
class Sphinx:
"""Implement the public-key reblinding technique based on Sphinx.
This does a few more public-key operations than it would strictly
need to if we were using a group implementation that (unlike nacl)
supported the operations we needed directly. The biggest issue is
that nacl insists the high bit is set on private keys, which means
we can't just multiply private keys together to get a new private
key, and do a single DH operation with that resulting key; we have
to perform a linear number of DH operations instead, per node in the
circuit, so a quadratic number of DH operations total."""
@staticmethod
def makeblindkey(shared_secret, domain_separator, perfstats):
"""Create a Sphinx reblinding key (a PrivateKey) out of a shared
secret and a domain separator (both bytestrings). The domain
separator is just a constant bytestring like b'data' or
b'circuit' for the data-protecting and circuit-protecting
public-key elements respectively."""
rawkey = nacl.hash.sha256(domain_separator + shared_secret,
encoder=nacl.encoding.RawEncoder)
perfstats.keygens += 1
# The PrivateKey constructor does the Curve25519 pinning of
# certain bits of the key to 0 and 1
return nacl.public.PrivateKey(rawkey)
@staticmethod
def reblindpubkey(blindkey, pubkey, perfstats):
"""Create a Sphinx reblinded PublicKey out of a reblinding key
(output by makeblindkey) and a (possibly already reblinded)
PublicKey."""
new_pubkey = nacl.bindings.crypto_scalarmult(bytes(blindkey),
bytes(pubkey))
perfstats.dhs += 1
return nacl.public.PublicKey(new_pubkey)
@staticmethod
def client(client_privkey, blindkey_list, server_pubkey,
domain_separator, is_last, perfstats):
"""Given the client's PrivateKey, a (possibly empty) list of
reblinding keys, and the server's PublicKey, produce the shared
secret and the new blinding key (to add to the list). The
domain separator is as above. If is_last is true, don't bother
creating the new blinding key, since this is the last iteration,
and we won't be using it."""
if type(server_pubkey) is bytes:
server_pubkey = nacl.public.PublicKey(server_pubkey)
reblinded_server_pubkey = server_pubkey
for blindkey in blindkey_list:
reblinded_server_pubkey = Sphinx.reblindpubkey(blindkey,
reblinded_server_pubkey, perfstats)
sharedsecret = nacl.public.Box(client_privkey,
reblinded_server_pubkey).shared_key()
perfstats.dhs += 1
if is_last:
blindkey = None
else:
blindkey = Sphinx.makeblindkey(sharedsecret,
domain_separator, perfstats)
return sharedsecret, blindkey
@staticmethod
def server(client_pubkey, server_privkey, domain_separator, is_last,
perfstats):
"""Given the client's PublicKey and the server's PrivateKey,
produce the shared secret and the new reblinded client
PublicKey. The domain separator is as above. If is_last is
True, don't bother generating the new PublicKey, since we're the
last server in the chain, and won't be using it."""
sharedsecret = nacl.public.Box(server_privkey,
client_pubkey).shared_key()
perfstats.dhs += 1
if is_last:
blinded_pubkey = None
else:
blindkey = Sphinx.makeblindkey(sharedsecret, domain_separator,
perfstats)
blinded_pubkey = Sphinx.reblindpubkey(blindkey, client_pubkey,
perfstats)
return sharedsecret, blinded_pubkey
class NTor:
"""A class implementing the ntor one-way authenticated key agreement
scheme. The details are not exactly the same as either the ntor
paper or Tor's implementation, but it will agree on keys and have
the same number of public key operations."""
def __init__(self, perfstats):
self.perfstats = perfstats
# Only used for Single-Pass Walking Onions; it is the sequence
# of blinding keys used by Sphinx
self.blinding_keys = []
def request(self):
"""Create the ntor request message: X = g^x."""
self.client_ephem_key = nacl.public.PrivateKey.generate()
self.perfstats.keygens += 1
return bytes(self.client_ephem_key.public_key)
@staticmethod
def reply(onion_privkey, idpubkey, client_pubkey, perfstats,
sphinx_domainsep=None):
"""The server calls this static method to produce the ntor reply
message: (Y = g^y, B = g^b, A = H(M, "verify")) and the shared
secret S = H(M, "secret") for M = (X^y,X^b,ID,B,X,Y). If
sphinx_domainsep is not None, also compute and return the Sphinx
reblinded client request to pass to the next server."""
if type(idpubkey) is not bytes:
idpubkey = bytes(idpubkey)
if type(client_pubkey) is bytes:
client_pubkey = nacl.public.PublicKey(client_pubkey)
server_ephem_key = nacl.public.PrivateKey.generate()
perfstats.keygens += 1
xykey = nacl.public.Box(server_ephem_key, client_pubkey).shared_key()
xbkey = nacl.public.Box(onion_privkey, client_pubkey).shared_key()
perfstats.dhs += 2
M = xykey + xbkey + \
idpubkey + \
onion_privkey.public_key.encode(encoder=nacl.encoding.RawEncoder) + \
server_ephem_key.public_key.encode(encoder=nacl.encoding.RawEncoder)
A = nacl.hash.sha256(M + b'verify', encoder=nacl.encoding.RawEncoder)
S = nacl.hash.sha256(M + b'secret', encoder=nacl.encoding.RawEncoder)
if sphinx_domainsep is not None:
blindkey = Sphinx.makeblindkey(S, sphinx_domainsep, perfstats)
blinded_client_pubkey = Sphinx.reblindpubkey(blindkey,
client_pubkey, perfstats)
return ((bytes(server_ephem_key.public_key),
bytes(onion_privkey.public_key), A),
S), blinded_client_pubkey
else:
return ((bytes(server_ephem_key.public_key),
bytes(onion_privkey.public_key), A), S)
def verify(self, reply, onion_pubkey, idpubkey, sphinx_domainsep=None):
"""The client calls this method to verify the ntor reply
message, passing the onion and id public keys for the server
it's expecting to be talking to. If sphinx_domainsep is not
None, also compute the reblinding key so that the client can
reuse this same NTor object for the next server. Returns the
shared secret on success, or raises ValueError on failure."""
server_ephem_pubkey, server_onion_pubkey, authtag = reply
if type(idpubkey) is not bytes:
idpubkey = bytes(idpubkey)
if type(server_ephem_pubkey) is bytes:
server_ephem_pubkey = nacl.public.PublicKey(server_ephem_pubkey)
if type(server_onion_pubkey) is bytes:
server_onion_pubkey = nacl.public.PublicKey(server_onion_pubkey)
if type(onion_pubkey) is bytes:
onion_pubkey = nacl.public.PublicKey(onion_pubkey)
if onion_pubkey != server_onion_pubkey:
raise ValueError("NTor onion pubkey mismatch")
# We use the blinding keys if present; if they're not present
# (because we're not in Single-Pass Walking Onions), the loops
# are just empty anyway, so everything will work in the usual
# unblinded way.
reblinded_server_ephem_pubkey = server_ephem_pubkey
for blindkey in self.blinding_keys:
reblinded_server_ephem_pubkey = Sphinx.reblindpubkey(blindkey,
reblinded_server_ephem_pubkey, self.perfstats)
xykey = nacl.public.Box(self.client_ephem_key,
reblinded_server_ephem_pubkey).shared_key()
reblinded_onion_pubkey = onion_pubkey
for blindkey in self.blinding_keys:
reblinded_onion_pubkey = Sphinx.reblindpubkey(blindkey,
reblinded_onion_pubkey, self.perfstats)
xbkey = nacl.public.Box(self.client_ephem_key,
reblinded_onion_pubkey).shared_key()
self.perfstats.dhs += 2
M = xykey + xbkey + \
idpubkey + \
onion_pubkey.encode(encoder=nacl.encoding.RawEncoder) + \
server_ephem_pubkey.encode(encoder=nacl.encoding.RawEncoder)
Acheck = nacl.hash.sha256(M + b'verify', encoder=nacl.encoding.RawEncoder)
S = nacl.hash.sha256(M + b'secret', encoder=nacl.encoding.RawEncoder)
if Acheck != authtag:
raise ValueError("NTor auth mismatch")
if sphinx_domainsep is not None:
blindkey = Sphinx.makeblindkey(S, sphinx_domainsep,
self.perfstats)
self.blinding_keys.append(blindkey)
return S
class VanillaExtendCircuitHandler:
"""A handler for VanillaExtendCircuitCell cells. It allocates a new
circuit id on the Channel to the requested next hop, connects the
existing and new circuits together, and forwards a
VanillaCreateCircuitMsg to the next hop."""
def received_cell(self, circhandler, cell):
# Remove ourselves from handling a second
# VanillaExtendCircuitCell on this circuit
circhandler.replace_celltype_handler(simcell.VanillaExtendCircuitCell, None)
# Allocate a new circuit id to the requested next hop
channelmgr = circhandler.channel.channelmgr
nexthopchannel = channelmgr.get_channel_to(cell.hopaddr)
newcircid, newcirchandler = nexthopchannel.new_circuit()
# Connect the existing and new circuits together
circhandler.adjacent_circuit_handler = newcirchandler
newcirchandler.adjacent_circuit_handler = circhandler
# Set up a handler for when the VanillaCreatedCircuitCell comes
# back
newcirchandler.replace_celltype_handler(
simcell.VanillaCreatedCircuitCell,
VanillaCreatedRelayHandler())
# Forward a VanillaCreateCircuitMsg to the next hop
nexthopchannel.send_msg(
simmsg.VanillaCreateCircuitMsg(newcircid, cell.ntor_request))
class TelescopingExtendCircuitHandler:
"""A handler for TelescopingExtendCircuitCell cells. It allocates a new
circuit id on the Channel to the requested next hop, connects the
existing and new circuits together, and forwards a
TelescopingCreateCircuitMsg to the next hop."""
def __init__(self, relaypicker, current_relay_idkey):
self.relaypicker = relaypicker
self.current_relay_idkey = bytes(current_relay_idkey)
def received_cell(self, circhandler, cell):
# Remove ourselves from handling a second
# TelescopingExtendCircuitCell on this circuit
circhandler.replace_celltype_handler(simcell.TelescopingExtendCircuitCell, None)
# Find the SNIP corresponding to the index sent by the client
next_snip = self.relaypicker.pick_relay_by_uniform_index(cell.idx)
# Check to make sure that we aren't extending to ourselves. If we are,
# close the circuit.
if next_snip.snipdict["idkey"] == self.current_relay_idkey:
logging.debug("Client requested extending the circuit to a relay already in the path; aborting. my circid: %s", str(circhandler.circid))
circhandler.close()
return
# Allocate a new circuit id to the requested next hop
channelmgr = circhandler.channel.channelmgr
nexthopchannel = channelmgr.get_channel_to(next_snip.snipdict["addr"])
newcircid, newcirchandler = nexthopchannel.new_circuit()
# Connect the existing and new circuits together
circhandler.adjacent_circuit_handler = newcirchandler
newcirchandler.adjacent_circuit_handler = circhandler
# Set up a handler for when the TelescopingCreatedCircuitCell comes
# back
newcirchandler.replace_celltype_handler(
simcell.TelescopingCreatedCircuitCell,
TelescopingCreatedRelayHandler(next_snip))
# Forward a TelescopingCreateCircuitMsg to the next hop
nexthopchannel.send_msg(
simmsg.TelescopingCreateCircuitMsg(newcircid, cell.ntor_request))
class VanillaCreatedRelayHandler:
"""Handle a VanillaCreatedCircuitCell received by a _relay_ that
recently received a VanillaExtendCircuitCell from a client, and so
forwarded a VanillaCreateCircuitCell to the next hop."""
def received_cell(self, circhandler, cell):
# Remove ourselves from handling a second
# VanillaCreatedCircuitCell on this circuit
circhandler.replace_celltype_handler(simcell.VanillaCreatedCircuitCell, None)
# Just forward a VanillaExtendedCircuitCell back towards the
# client
circhandler.adjacent_circuit_handler.send_cell(
simcell.VanillaExtendedCircuitCell(cell.ntor_reply))
class TelescopingCreatedRelayHandler:
"""Handle a TelescopingCreatedCircuitCell received by a _relay_ that
recently received a TelescopingExtendCircuitCell from a client, and so
forwarded a TelescopingCreateCircuitCell to the next hop."""
def __init__(self, next_snip):
self.next_snip = next_snip
def received_cell(self, circhandler, cell):
logging.debug("Handle a TelescopingCreatedCircuit received by a relay")
# Remove ourselves from handling a second
# TelescopingCreatedCircuitCell on this circuit
circhandler.replace_celltype_handler(simcell.TelescopingCreatedCircuitCell, None)
# Just forward a TelescopingExtendedCircuitCell back towards the
# client
circhandler.adjacent_circuit_handler.send_cell(
simcell.TelescopingExtendedCircuitCell(cell.ntor_reply, self.next_snip))
class SinglePassCreatedRelayHandler:
"""Handle a SinglePassCreatedCircuitCell received by a _relay_ that
recently received a SinglePassCreateCircuitMsg from this relay."""
def __init__(self, ntorreply, next_snip, vrf_output, createdkey):
self.ntorreply = ntorreply
self.next_snip = next_snip
self.vrf_output = vrf_output
self.createdkey = createdkey
def received_cell(self, circhandler, cell):
logging.debug("Handle a SinglePassCreatedCircuitCell received by a relay")
# Remove ourselves from handling a second
# SinglePassCreatedCircuitCell on this circuit
circhandler.replace_celltype_handler(simcell.SinglePassCreatedCircuitCell, None)
logging.debug("Sending a SinglePassCreatedCell after receiving one from %s", self.next_snip.snipdict['addr'])
# Forward a SinglePassCreatedCircuitCell back towards the client
circhandler.adjacent_circuit_handler.channel_send_cell(
simcell.SinglePassCreatedCircuitCell(self.ntorreply,
simcell.SinglePassCreatedEnc(self.createdkey, self.next_snip,
self.vrf_output, cell)))
class CircuitHandler:
"""A class for managing sending and receiving encrypted cells on a
particular circuit."""
class NoCryptLayer:
def encrypt_msg(self, message): return message
def decrypt_msg(self, message): return message
class CryptLayer:
def __init__(self, enckey, deckey, next_layer):
self.enckey = enckey
self.deckey = deckey
self.next_layer = next_layer
def encrypt_msg(self, message):
return self.next_layer.encrypt_msg(simcell.EncryptedCell(self.enckey, message))
def decrypt_msg(self, message):
return self.next_layer.decrypt_msg(message).decrypt(self.deckey)
def __init__(self, channel, circid):
self.channel = channel
self.circid = circid
# The list of relay descriptors that form the circuit so far
# (client side only)
self.circuit_descs = []
# The dispatch table is indexed by type, and the values are
# objects with received_cell(circhandler, cell) methods.
self.cell_dispatch_table = dict()
# The topmost crypt layer. This is an object with
# encrypt_msg(msg) and decrypt_msg(msg) methods that returns the
# en/decrypted messages respectively. Messages are encrypted
# starting with the last layer that was added (the keys for the
# furthest away relay in the circuit) and are decrypted starting
# with the first layer that was added (the keys for the guard).
self.crypt_layer = self.NoCryptLayer()
# The adjacent CircuitHandler that's connected to this one. If
# we get a cell on one, we forward it to the other (if it's not
# meant for us to handle directly)
self.adjacent_circuit_handler = None
# The function to call when this circuit closes
self.closer = lambda: self.channel.circuithandlers.pop(circid)
def close(self):
"""Close the circuit. Sends a CloseCell on the circuit (and its
adjacent circuit, if present) and closes both."""
adjcirchandler = self.adjacent_circuit_handler
self.adjacent_circuit_handler = None
logging.debug("Closing circuit. circid: %s", str(self.circid))
if adjcirchandler is not None:
adjcirchandler.adjacent_circuit_handler = None
self.closer()
self.channel_send_cell(simcell.CloseCell())
if adjcirchandler is not None:
adjcirchandler.closer()
adjcirchandler.channel_send_cell(simcell.CloseCell())
def send_cell(self, cell):
"""Send a cell on this circuit, encrypting as needed."""
self.channel_send_cell(self.crypt_layer.encrypt_msg(cell))
def channel_send_cell(self, cell):
"""Send a cell on this circuit directly without encrypting it
first."""
self.channel.send_msg(simmsg.CircuitCellMsg(self.circid, cell))
def received_cell(self, cell):
"""A cell has been received on this circuit. Dispatch it
according to its type."""
if isinstance(cell, simcell.EncryptedCell):
cell = self.crypt_layer.decrypt_msg(cell)
logging.debug("CircuitHandler: %s received cell %s on circuit %d from %s" % (self.channel.channelmgr.myaddr, cell, self.circid, self.channel.peer.channelmgr.myaddr))
# If it's still encrypted, it's for sure meant for forwarding to
# our adjacent hop, which had better exist.
if isinstance(cell, simcell.EncryptedCell):
self.adjacent_circuit_handler.send_cell(cell)
else:
# This is a plaintext cell meant for us. Handle it
# according to the table.
celltype = type(cell)
if celltype in self.cell_dispatch_table:
self.cell_dispatch_table[celltype].received_cell(self, cell)
elif isinstance(cell, simcell.StringCell):
# Default handler; just print the message in the cell
logging.debug("CircuitHandler: %s received '%s' on circuit %d from %s" \
% (self.channel.channelmgr.myaddr, cell,
self.circid, self.channel.peer.channelmgr.myaddr))
elif isinstance(cell, simcell.CloseCell):
logging.debug("Received CloseCell on circuit %s", str(self.circid))
# Forward the CloseCell (without encryption) to the
# adjacent circuit, if any, and close both this and the
# adjacent circuit
adjcirchandler = self.adjacent_circuit_handler
self.adjacent_circuit_handler = None
if adjcirchandler is not None:
adjcirchandler.adjacent_circuit_handler = None
self.closer()
if adjcirchandler is not None:
adjcirchandler.closer()
adjcirchandler.channel_send_cell(cell)
else:
# I don't know how to handle this cell?
raise ValueError("CircuitHandler: %s received unknown cell type %s on circuit %d from %s" \
% (self.channel.channelmgr.myaddr, cell,
self.circid, self.channel.peer.channelmgr.myaddr))
def replace_celltype_handler(self, celltype, handler):
"""Add an object with a received_cell(circhandler, cell) method
to the cell dispatch table. It replaces anything that's already
there. Passing None as the handler removes the dispatcher for
that cell type."""
if handler is None:
del self.cell_dispatch_table[celltype]
else:
self.cell_dispatch_table[celltype] = handler
def add_crypt_layer(self, enckey, deckey):
"""Add a processing layer to this CircuitHandler so that cells
we send will get encrypted with the first given key, and cells
we receive will be decrypted with the other given key."""
current_crypt_layer = self.crypt_layer
self.crypt_layer = self.CryptLayer(enckey, deckey, current_crypt_layer)
class Channel(Connection):
"""A class representing a channel between a relay and either a
client or a relay, transporting cells from various circuits."""
def __init__(self):
super().__init__()
# The RelayChannelManager managing this Channel
self.channelmgr = None
# The Channel at the other end
self.peer = None
# The function to call when the connection closes
self.closer = lambda: None
# The next circuit id to use on this channel. The party that
# opened the channel uses even numbers; the receiving party uses
# odd numbers.
self.next_circid = None
# A map for CircuitHandlers to use for each open circuit on the
# channel
self.circuithandlers = dict()
def closed(self):
# Close each circuithandler we're managing
while self.circuithandlers:
chitems = iter(self.circuithandlers.items())
circid, circhandler = next(chitems)
logging.debug('closing circuit %s', circid)
circhandler.close()
self.closer()
self.peer = None
def close(self):
peer = self.peer
self.closed()
if peer is not None and peer is not self:
peer.closed()
def new_circuit(self):
"""Allocate a new circuit on this channel, returning the new
circuit's id and the new CircuitHandler."""
circid = self.next_circid
self.next_circid += 2
circuithandler = CircuitHandler(self, circid)
self.circuithandlers[circid] = circuithandler
return circid, circuithandler
def is_circuit_open(self, circid):
is_open = (circid in self.circuithandlers) and (self.circuithandlers[circid] is not None)
return is_open
def new_circuit_with_circid(self, circid):
"""Allocate a new circuit on this channel, with the circuit id
received from our peer. Return the new CircuitHandler"""
circuithandler = CircuitHandler(self, circid)
self.circuithandlers[circid] = circuithandler
return circuithandler
def send_cell(self, circid, cell):
"""Send the given message on the given circuit, encrypting or
decrypting as needed."""
self.circuithandlers[circid].send_cell(cell)
def send_raw_cell(self, circid, cell):
"""Send the given message, tagged for the given circuit id. No
encryption or decryption is done."""
self.send_msg(simmsg.CircuitCellMsg(self.circid, self.cell))
def send_msg(self, message):
"""Send the given NetMsg on the channel."""
self.channelmgr.perfstats.bytes_sent += message.size()
self.peer.received(self.channelmgr.myaddr, message)
def received(self, peeraddr, message):
"""Callback when a message is received from the network."""
logging.debug('Channel: %s received %s from %s' % (self.channelmgr.myaddr, message, peeraddr))
self.channelmgr.perfstats.bytes_received += message.size()
if isinstance(message, simmsg.CircuitCellMsg):
circid, cell = message.circid, message.cell
self.circuithandlers[circid].received_cell(cell)
else:
self.channelmgr.received_msg(message, peeraddr, self)
class ChannelManager:
"""The class that manages the channels to other relays and clients.
Relays and clients both use subclasses of this class to both create
on-demand channels to relays, to gracefully handle the closing of
channels, and to handle commands received over the channels."""
def __init__(self, myaddr, dirauthaddrs, perfstats):
# A dictionary of Channels to other hosts, indexed by NetAddr
self.channels = dict()
self.myaddr = myaddr
self.dirauthaddrs = dirauthaddrs
self.consensus = None
self.relaypicker = None
self.perfstats = perfstats
def terminate(self):
"""Close all connections we're managing."""
while self.channels:
channelitems = iter(self.channels.items())
addr, channel = next(channelitems)
logging.debug('closing channel %s %s', addr, channel)
channel.close()
def add_channel(self, channel, peeraddr):
"""Add the given channel to the list of channels we are
managing. If we are already managing a channel to the same
peer, close it first."""
if peeraddr in self.channels:
self.channels[peeraddr].close()
channel.channelmgr = self
self.channels[peeraddr] = channel
channel.closer = lambda: self.channels.pop(peeraddr)
def get_channel_to(self, addr):
"""Get the Channel connected to the given NetAddr, creating one
if none exists right now."""
if addr in self.channels:
return self.channels[addr]
# Create the new channel
logging.debug('getting channel from %s to %s',self.myaddr,addr)
newchannel = network.thenetwork.connect(self.myaddr, addr,
self.perfstats)
logging.debug('got channel from %s to %s',self.myaddr,addr)
self.channels[addr] = newchannel
newchannel.closer = lambda: self.channels.pop(addr)
newchannel.channelmgr = self
return newchannel
def received_msg(self, message, peeraddr, channel):
"""Callback when a NetMsg not specific to a circuit is
received."""
logging.debug("ChannelManager: Node %s received msg %s from %s" % (self.myaddr, message, peeraddr))
def received_cell(self, circid, cell, peeraddr, channel):
"""Callback with a circuit-specific cell is received."""
logging.debug("ChannelManager: Node %s received cell on circ %d: %s from %s" % (self.myaddr, circid, cell, peeraddr))
def send_msg(self, message, peeraddr):
"""Send a message to the peer with the given address."""
channel = self.get_channel_to(peeraddr)
channel.send_msg(message)
def send_cell(self, circid, cell, peeraddr):
"""Send a cell on the given circuit to the peer with the given
address."""
channel = self.get_channel_to(peeraddr)
channel.send_cell(circid, cell)
class RelayChannelManager(ChannelManager):
"""The subclass of ChannelManager for relays."""
def __init__(self, myaddr, dirauthaddrs, onionprivkey, idpubkey,
desc_getter, path_selection_key_getter, perfstats):
super().__init__(myaddr, dirauthaddrs, perfstats)
self.onionkey = onionprivkey
self.idpubkey = idpubkey
if network.thenetwork.womode != network.WOMode.VANILLA:
self.endive = None
self.desc_getter = desc_getter
if network.thenetwork.womode == network.WOMode.SINGLEPASS:
self.path_selection_key_getter = path_selection_key_getter
def get_consensus(self):
"""Download a fresh consensus (and ENDIVE if using Walking
Onions) from a random dirauth."""
a = random.choice(self.dirauthaddrs)
c = network.thenetwork.connect(self, a, self.perfstats)
if network.thenetwork.womode == network.WOMode.VANILLA:
if self.consensus is not None and \
len(self.consensus.consdict['relays']) > 0:
self.consensus = c.getconsensusdiff()
else:
self.consensus = c.getconsensus()
logging.debug("Relay %s requests consensus from %s", self.myaddr, str(network.thenetwork.dirauthkeys()))
self.relaypicker = dirauth.Consensus.verify(self.consensus,
network.thenetwork.dirauthkeys(), self.perfstats)
else:
self.consensus = c.getconsensus()
if self.endive is not None and \
len(self.endive.enddict['snips']) > 0:
self.endive = c.getendivediff()
else:
self.endive = c.getendive()
self.relaypicker = dirauth.ENDIVE.verify(self.endive,
self.consensus, network.thenetwork.dirauthkeys(),
self.perfstats)
c.close()
def received_msg(self, message, peeraddr, channel):
"""Callback when a NetMsg not specific to a circuit is
received."""
logging.debug("RelayChannelManager: Node %s received msg %s from %s" % (self.myaddr, message, peeraddr))
if isinstance(message, simmsg.RelayRandomHopMsg):
if message.ttl > 0:
# Pick a random next hop from the consensus
nexthop = self.relaypicker.pick_weighted_relay()
if network.thenetwork.womode == network.WOMode.VANILLA:
nextaddr = nexthop.descdict["addr"]
else:
nextaddr = nexthop.snipdict["addr"]
self.send_msg(simmsg.RelayRandomHopMsg(message.ttl-1), nextaddr)
elif isinstance(message, simmsg.RelayGetConsensusMsg):
self.send_msg(simmsg.RelayConsensusMsg(self.consensus), peeraddr)
elif isinstance(message, simmsg.RelayGetConsensusDiffMsg):
self.send_msg(simmsg.RelayConsensusDiffMsg(self.consensus), peeraddr)
elif isinstance(message, simmsg.RelayGetDescMsg):
self.send_msg(simmsg.RelayDescMsg(self.desc_getter()), peeraddr)
elif isinstance(message, simmsg.VanillaCreateCircuitMsg):
# A new circuit has arrived
circhandler = channel.new_circuit_with_circid(message.circid)
# Create the ntor reply
reply, secret = NTor.reply(self.onionkey, self.idpubkey,
message.ntor_request, self.perfstats)
# Set up the circuit to use the shared secret
enckey = nacl.hash.sha256(secret + b'downstream')
deckey = nacl.hash.sha256(secret + b'upstream')
circhandler.add_crypt_layer(enckey, deckey)
# Add a handler for if an Extend Cell arrives (there should
# be at most one on this circuit).
circhandler.replace_celltype_handler(
simcell.VanillaExtendCircuitCell, VanillaExtendCircuitHandler())
# Send the ntor reply
self.send_msg(simmsg.CircuitCellMsg(message.circid,
simcell.VanillaCreatedCircuitCell(reply)), peeraddr)
elif isinstance(message, simmsg.TelescopingCreateCircuitMsg):
# A new circuit has arrived
circhandler = channel.new_circuit_with_circid(message.circid)
# Create the ntor reply
reply, secret = NTor.reply(self.onionkey, self.idpubkey,
message.ntor_request, self.perfstats)
# Set up the circuit to use the shared secret
enckey = nacl.hash.sha256(secret + b'downstream')
deckey = nacl.hash.sha256(secret + b'upstream')
circhandler.add_crypt_layer(enckey, deckey)
# Add a handler for if an Extend Cell arrives (there should
# be at most one on this circuit).
circhandler.replace_celltype_handler(
simcell.TelescopingExtendCircuitCell,
TelescopingExtendCircuitHandler(self.relaypicker,
self.idpubkey))
# Send the ntor reply
self.send_msg(simmsg.CircuitCellMsg(message.circid,
simcell.TelescopingCreatedCircuitCell(reply)), peeraddr)
elif isinstance(message, simmsg.SinglePassCreateCircuitMsg) and message.ttl == 0:
# we are the end of the circuit, just establish a shared key and
# return
logging.debug("RelayChannelManager: Single-Pass TTL is 0, replying without extending")
# A new circuit has arrived
circhandler = channel.new_circuit_with_circid(message.circid)
# Create the ntor reply
reply, secret = NTor.reply(self.onionkey, self.idpubkey,
message.ntor_request, self.perfstats)
# Set up the circuit to use the shared secret
enckey = nacl.hash.sha256(secret + b'downstream')
deckey = nacl.hash.sha256(secret + b'upstream')
circhandler.add_crypt_layer(enckey, deckey)
# Send the ntor reply, but no need to send the snip for the next
# relay or vrf proof, as this is the last relay in the circuit.
self.send_msg(simmsg.CircuitCellMsg(message.circid,
simcell.SinglePassCreatedCircuitCell(reply, None)), peeraddr)
elif isinstance(message, simmsg.SinglePassCreateCircuitMsg) and message.ttl > 0:
logging.debug("RelayChannelManager: Single-Pass TTL is greater than 0; extending")
# A new circuit has arrived
circhandler = channel.new_circuit_with_circid(message.circid)
# Create the ntor reply for the circuit-extension key, and derive
# the client's next blinded key
(ntorreply, secret), blinded_client_encr_key = \
NTor.reply(self.onionkey, self.idpubkey,
message.ntor_request, self.perfstats, b'circuit')
# Set up the circuit to use the shared secret established from the
# circuit extension key
enckey = nacl.hash.sha256(secret + b'downstream')
deckey = nacl.hash.sha256(secret + b'upstream')
createdkey = nacl.hash.sha256(secret + b'created')
# Here, we will directly extend the circuit ourselves, after
# determining the next relay using the client's path selection
# key in conjunction with our own
pathsel_rand, blinded_client_path_selection_key = \
Sphinx.server(nacl.public.PublicKey(message.clipathselkey),
self.onionkey, b'pathsel', False, self.perfstats)
pathselkey = self.path_selection_key_getter()
# Simulate the VRF output for now (but it has the right
# size, and charges the right number of group operations to
# the perfstats)
vrf_output = VRF.get_output(pathselkey, pathsel_rand,
self.perfstats)
index = int.from_bytes(vrf_output[0][:4], 'big', signed=False)
next_hop = self.relaypicker.pick_relay_by_uniform_index(index)
if next_hop == None:
logging.debug("Client requested extending the circuit to a relay index that results in None, aborting. my circid: %s", str(circhandler.circid))
circhandler.close()
elif next_hop.snipdict["idkey"] == bytes(self.idpubkey):
logging.debug("Client requested extending the circuit to a relay already in the path; aborting. my circid: %s", str(circhandler.circid))
circhandler.close()
return
# Allocate a new circuit id to the requested next hop
channelmgr = circhandler.channel.channelmgr
nexthopchannel = channelmgr.get_channel_to(next_hop.snipdict["addr"])
newcircid, newcirchandler = nexthopchannel.new_circuit()
# Connect the existing and new circuits together
circhandler.adjacent_circuit_handler = newcirchandler
newcirchandler.adjacent_circuit_handler = circhandler
# Add a handler for once the next relay replies to say that the
# circuit has been created
newcirchandler.replace_celltype_handler(
simcell.SinglePassCreatedCircuitCell,
SinglePassCreatedRelayHandler(ntorreply, next_hop,
vrf_output, createdkey))
# Send the next create message to the next hop
nexthopchannel.send_msg(simmsg.SinglePassCreateCircuitMsg(newcircid,
blinded_client_encr_key, blinded_client_path_selection_key,
message.ttl-1))
# Now set up the crypto
circhandler.add_crypt_layer(enckey, deckey)
else:
return super().received_msg(message, peeraddr, channel)
def received_cell(self, circid, cell, peeraddr, channel):
"""Callback with a circuit-specific cell is received."""
logging.debug("RelayChannelManager: Node %s received cell on circ %d: %s from %s" % (self.myaddr, circid, cell, peeraddr))
return super().received_cell(circid, cell, peeraddr, channel)
class Relay(network.Server):
"""The class representing an onion relay."""
def __init__(self, dirauthaddrs, bw, flags):
idkey = nacl.signing.SigningKey.generate()
name = idkey.verify_key.encode(encoder=nacl.encoding.HexEncoder).decode("ascii")
# Gather performance statistics
self.perfstats = network.PerfStats(network.EntType.RELAY, bw)
self.perfstats.is_bootstrapping = True
# Create the identity and onion keys
self.idkey = idkey
self.onionkey = nacl.public.PrivateKey.generate()
self.perfstats.keygens += 2
self.name = name
# Bind to the network to get a network address
self.netaddr = network.thenetwork.bind(self)
self.perfstats.name = "Relay at %s" % self.netaddr
# Our bandwidth and flags
self.bw = bw
self.flags = flags
# Register for epoch change notification
network.thenetwork.wantepochticks(self, True, priority=True, end=True)
network.thenetwork.wantepochticks(self, True, priority=True)
self.current_desc = None
self.next_desc = None
# Create the path selection key for Single-Pass Walking Onions
if network.thenetwork.womode == network.WOMode.SINGLEPASS:
self.path_selection_key = nacl.public.PrivateKey.generate()
self.next_path_selection_key = self.path_selection_key
self.perfstats.keygens += 1
else:
self.path_selection_key = None
# Create the RelayChannelManager connection manager
self.channelmgr = RelayChannelManager(self.netaddr, dirauthaddrs,
self.onionkey, self.idkey.verify_key,
lambda: self.current_desc, lambda: self.path_selection_key,
self.perfstats)
# Initially, we're not a fallback relay
self.is_fallbackrelay = False
self.uploaddesc()
def terminate(self):
"""Stop this relay."""
if self.is_fallbackrelay:
# Fallback relays must not (for now) terminate
raise RelayFallbackTerminationError(self)
# Stop listening for epoch ticks
network.thenetwork.wantepochticks(self, False, priority=True, end=True)
network.thenetwork.wantepochticks(self, False, priority=True)
# Tell the dirauths we're going away
self.uploaddesc(False)
# Close connections to other relays
self.channelmgr.terminate()
# Stop listening to our own bound port
self.close()
def set_is_fallbackrelay(self, isfallback = True):
"""Set this relay to be a fallback relay (or unset if passed
False)."""
self.is_fallbackrelay = isfallback
def epoch_ending(self, epoch):
# Download the new consensus, which will have been created
# already since the dirauths' epoch_ending callbacks happened
# before the relays'.
self.channelmgr.get_consensus()
def newepoch(self, epoch):
# Rotate the path selection key for Single-Pass Walking Onions
if network.thenetwork.womode == network.WOMode.SINGLEPASS:
self.path_selection_key = self.next_path_selection_key
self.next_path_selection_key = nacl.public.PrivateKey.generate()
self.perfstats.keygens += 1
# Upload the descriptor for the *next* epoch (the one after the
# one that just started)
self.uploaddesc()
def uploaddesc(self, upload=True):
# Upload the descriptor for the epoch to come, or delete a
# previous upload if upload=False
descdict = dict()
descdict["epoch"] = network.thenetwork.getepoch() + 1
descdict["idkey"] = bytes(self.idkey.verify_key)
descdict["onionkey"] = bytes(self.onionkey.public_key)
descdict["addr"] = self.netaddr
descdict["bw"] = self.bw
descdict["flags"] = self.flags
if network.thenetwork.womode == network.WOMode.SINGLEPASS:
descdict["pathselkey"] = \
bytes(self.next_path_selection_key.public_key)
desc = dirauth.RelayDescriptor(descdict)
desc.sign(self.idkey, self.perfstats)
dirauth.RelayDescriptor.verify(desc, self.perfstats)
self.current_desc = self.next_desc
self.next_desc = desc
if upload:
descmsg = simmsg.DirAuthUploadDescMsg(desc)
else:
# Note that this relies on signatures being deterministic;
# otherwise we'd need to save the descriptor we uploaded
# before so we could tell the airauths to delete the exact
# one
descmsg = simmsg.DirAuthDelDescMsg(desc)
# Upload them
for a in self.channelmgr.dirauthaddrs:
c = network.thenetwork.connect(self, a, self.perfstats)
c.sendmsg(descmsg)
c.close()
def connected(self, peer):
"""Callback invoked when someone (client or relay) connects to
us. Create a pair of linked Channels and return the peer half
to the peer."""
# Create the linked pair
if peer is self.netaddr:
# A self-loop? We'll allow it.
peerchannel = Channel()
peerchannel.peer = peerchannel
peerchannel.next_circid = 2
return peerchannel
peerchannel = Channel()
ourchannel = Channel()
peerchannel.peer = ourchannel
peerchannel.next_circid = 2
ourchannel.peer = peerchannel
ourchannel.next_circid = 1
# Add our channel to the RelayChannelManager
self.channelmgr.add_channel(ourchannel, peer)
return peerchannel