def verify_balance_proof(self, sender, open_block_number, balance,
signature):
"""Verify that a balance proof is valid and return the sender.
Does not check the balance itself.
:returns: the channel
"""
if (sender, open_block_number) in self.unconfirmed_channels:
raise InsufficientConfirmations(
'Insufficient confirmations for the channel '
'(sender=%s, open_block_number=%d)' %
(sender, open_block_number))
try:
c = self.channels[sender, open_block_number]
except KeyError:
raise NoOpenChannel('Channel does not exist or has been closed'
'(sender=%s, open_block_number=%s)' %
(sender, open_block_number))
if c.is_closed:
raise NoOpenChannel('Channel closing has been requested already.')
if not is_same_address(
verify_balance_proof(self.receiver, open_block_number, balance,
decode_hex(signature)), sender):
raise InvalidBalanceProof(
'Recovered signer does not match the sender')
return c
def on_invalid_amount(self, method: str, url: str, response: Response,
**kwargs) -> bool:
log.debug('Server claims an invalid amount sent.')
balance_sig = response.headers.get(HTTPHeaders.BALANCE_SIGNATURE)
if balance_sig:
balance_sig = decode_hex(balance_sig)
last_balance = int(response.headers.get(HTTPHeaders.SENDER_BALANCE))
channel = self.get_channel(url)
verified = balance_sig and is_same_address(
verify_balance_proof(
channel.receiver, channel.block, last_balance, balance_sig,
self.client.channel_manager_address), channel.sender)
if verified:
if last_balance == channel.balance:
log.error(
'Server tried to disguise the last unconfirmed payment as a confirmed payment.'
)
return False
else:
log.debug(
'Server provided proof for a different channel balance ({}). Adopting.'
.format(last_balance))
channel.update_balance(last_balance)
else:
log.debug(
'Server did not provide proof for a different channel balance. Reverting to 0.'
)
channel.update_balance(0)
return self.on_payment_requested(method, url, response, **kwargs)
def test_verify_balance_proof_v0(channel_manager_contract_address: str):
sig = sign_balance_proof(SENDER_PRIVATE_KEY, RECEIVER_ADDR, 312524, 11,
channel_manager_contract_address)
sig = sig[:-1] + b'\x00'
assert verify_balance_proof(
RECEIVER_ADDR, 312524, 11, sig,
channel_manager_contract_address) == SENDER_ADDR
def test_verify_balance_proof_v27(channel_manager_contract_address: str):
# Should be default but test anyway.
sig = sign_balance_proof(SENDER_PRIVATE_KEY, RECEIVER_ADDR, 312524, 11,
channel_manager_contract_address)
sig = sig[:-1] + b'\x1b'
assert verify_balance_proof(
RECEIVER_ADDR, 312524, 11, sig,
channel_manager_contract_address) == SENDER_ADDR
def _sync_balance(self, balance: int, balance_sig: bytes) -> bool:
if not self.channel:
# Nothing to verify or sync. Server does not know about a channel yet.
return True
elif not balance:
# Server does know about the channel but cannot confirm its creation yet.
log.info(
'Server could not confirm new channel yet. Waiting for {} seconds.'
.format(self.retry_interval))
time.sleep(self.retry_interval)
self.retry = True
return False
verified = balance_sig and is_same_address(
verify_balance_proof(self.channel.receiver, self.channel.block,
balance, balance_sig), self.channel.sender)
if balance > self.channel.balance:
if verified:
log.info(
'Server proved a higher channel balance (server/local): {}/{}. Adopting.'
.format(balance, self.channel.balance))
self.channel.balance = balance
else:
log.error(
'Server could not prove higher channel balance (server/local): {}/{}'
.format(balance, self.channel.balance))
return False
elif balance < self.channel.balance:
if verified:
log.info(
'Server sent older balance proof or rejected the last one (server/local): '
'{}/{}. Possibly because of an unconfirmed topup. Retrying in {} seconds.'
.format(balance, self.channel.balance,
self.retry_interval))
self.channel.balance = balance
time.sleep(self.retry_interval)
self.retry = True
return False
else:
log.info(
'Server sent lower balance without proof. Attempting to continue on lower '
'balance (server/local): {}.'.format(
balance, self.channel.balance))
self.channel.balance = balance
return True
def close_cooperatively(self, closing_sig: bytes):
"""
Attempts to close the channel immediately by providing a hash of the channel's balance
proof signed by the receiver. This signature must correspond to the balance proof stored in
the passed channel state.
"""
if self.state == Channel.State.closed:
log.error(
'Channel must not be closed already to be closed cooperatively.'
)
return None
log.info(
'Attempting to cooperatively close channel to {} created at block #{}.'
.format(self.receiver, self.block))
current_block = self.client.web3.eth.blockNumber
if not is_same_address(
verify_balance_proof(self.receiver, self.block, self.balance,
closing_sig), self.receiver):
log.error('Invalid closing signature.')
return None
tx = self.client.channel_manager_proxy.create_signed_transaction(
'close', [
self.receiver, self.block, self.balance, self.balance_sig,
closing_sig
])
self.client.web3.eth.sendRawTransaction(tx)
log.info('Waiting for settle confirmation event...')
event = self.client.channel_manager_proxy.get_channel_settle_event_blocking(
self.sender, self.receiver, self.block, current_block + 1)
if event:
log.info('Successfully closed channel in block {}.'.format(
event['blockNumber']))
self.state = Channel.State.closed
self.client.store_channels()
return event
else:
log.error('No event received.')
return None
def test_verify_balance_proof():
sig = sign_balance_proof(SENDER_PRIVATE_KEY, RECEIVER_ADDR, 315123, 8)
assert verify_balance_proof(RECEIVER_ADDR, 315123, 8, sig) == SENDER_ADDR
def test_verify_balance_proof_v27():
# Should be default but test anyway.
sig = sign_balance_proof(SENDER_PRIVATE_KEY, RECEIVER_ADDR, 312524, 11)
sig = sig[:-1] + b'\x1b'
assert verify_balance_proof(RECEIVER_ADDR, 312524, 11, sig) == SENDER_ADDR
def test_verify_balance_proof_v0():
sig = sign_balance_proof(SENDER_PRIVATE_KEY, RECEIVER_ADDR, 312524, 11)
sig = sig[:-1] + b'\x00'
assert verify_balance_proof(RECEIVER_ADDR, 312524, 11, sig) == SENDER_ADDR
def test_verify_balance_proof(channel_manager_contract_address: str):
sig = sign_balance_proof(SENDER_PRIVATE_KEY, RECEIVER_ADDR, 315123, 8,
channel_manager_contract_address)
assert verify_balance_proof(
RECEIVER_ADDR, 315123, 8, sig,
channel_manager_contract_address) == SENDER_ADDR
