def should_join_circuit(self, create_payload, previous_node_address):
"""
Check whether we should join a circuit. Returns a deferred that fires with a boolean.
"""
if self.settings.max_joined_circuits <= len(self.relay_from_to) + len(self.exit_sockets):
self.logger.warning("too many relays (%d)", (len(self.relay_from_to) + len(self.exit_sockets)))
return succeed(False)
# Check whether we have a random open slot, if so, allocate this to this request.
circuit_id = create_payload.circuit_id
for index, slot in enumerate(self.random_slots):
if not slot:
self.random_slots[index] = circuit_id
return succeed(True)
# No random slots but this user might be allocated a competing slot.
# Next, we request the token balance of the circuit initiator.
balance_deferred = Deferred()
self.request_cache.add(BalanceRequestCache(self, circuit_id, balance_deferred))
# Temporarily add these values, otherwise we are unable to communicate with the previous hop.
self.directions[circuit_id] = EXIT_NODE
shared_secret, _, _ = self.crypto.generate_diffie_shared_secret(create_payload.key)
self.relay_session_keys[circuit_id] = self.crypto.generate_session_keys(shared_secret)
self.send_cell([Peer(create_payload.node_public_key, previous_node_address)], u"balance-request",
BalanceRequestPayload(circuit_id))
self.directions.pop(circuit_id, None)
self.relay_session_keys.pop(circuit_id, None)
return balance_deferred
def on_balance_request_cell(self, source_address, data, _):
payload = self._ez_unpack_noauth(BalanceRequestPayload, data, global_time=False)
circuit_id = payload.circuit_id
request = self.request_cache.get(u"anon-circuit", circuit_id)
if request.should_forward:
forwarding_relay = RelayRoute(request.from_circuit_id, request.peer)
self.send_cell([forwarding_relay.peer.address], u"relay-balance-request",
BalanceRequestPayload(forwarding_relay.circuit_id))
else:
self.on_balance_request(payload)
def on_balance_request_cell(self, source_address, data, _):
_, payload = self._ez_unpack_noauth(BalanceRequestPayload, data)
circuit_id = payload.circuit_id
request = self.request_cache.get(u"anon-circuit", circuit_id)
if request.should_forward:
forwarding_relay = RelayRoute(request.from_circuit_id,
request.candidate_sock_addr,
mid=request.candidate_mid)
self.send_cell([forwarding_relay.sock_addr], u"relay-balance-request",
BalanceRequestPayload(forwarding_relay.circuit_id))
else:
self.on_balance_request(payload)
def on_balance_request_cell(self, source_address, data, _):
payload = self._ez_unpack_noauth(BalanceRequestPayload,
data,
global_time=False)
if self.request_cache.has(u"create", payload.circuit_id):
request = self.request_cache.get(u"create", payload.circuit_id)
forwarding_relay = RelayRoute(request.from_circuit_id,
request.peer)
self.send_cell([forwarding_relay.peer.address],
u"relay-balance-request",
BalanceRequestPayload(forwarding_relay.circuit_id))
elif self.request_cache.has(u"circuit", payload.circuit_id):
self.on_balance_request(payload)
else:
self.logger.warning("Circuit creation cache for id %s not found!",
payload.circuit_id)
