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LBRY-Vault/electrum/lnchan.py
Janus 47c07f77b4 lnsweep: fix create_sweeptxs_for_their_just_revoked_ctx 
in the case where an htlc is failed, it could happen
that we use the wrong list of htlcs to generate sweep
tx'es. we would use the pending list instead of the
committed list.

observed by sending 12300sat and then 123000sat,
the second payment fails and an AssertionError was
triggered cause the htlc output could not be found
in the ctx.

added some documentation to clarify the behaviour
of lnchan.included_htlcs.
2019-08-20 09:03:11 +02:00

892 lines
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# Copyright (C) 2018 The Electrum developers
# Copyright (C) 2015-2018 The Lightning Network Developers
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
# API (method signatures and docstrings) partially copied from lnd
# 42de4400bff5105352d0552155f73589166d162b
from collections import namedtuple, defaultdict
import binascii
import json
from enum import Enum, auto
from typing import Optional, Dict, List, Tuple, NamedTuple, Set, Callable, Iterable, Sequence
from copy import deepcopy
from .util import bfh, PrintError, bh2u
from .bitcoin import TYPE_SCRIPT, TYPE_ADDRESS
from .bitcoin import redeem_script_to_address
from .crypto import sha256, sha256d
from . import ecc
from .lnutil import Outpoint, LocalConfig, RemoteConfig, Keypair, OnlyPubkeyKeypair, ChannelConstraints, RevocationStore
from .lnutil import get_per_commitment_secret_from_seed
from .lnutil import secret_to_pubkey, derive_privkey, derive_pubkey, derive_blinded_pubkey
from .lnutil import sign_and_get_sig_string
from .lnutil import make_htlc_tx_with_open_channel, make_commitment, make_received_htlc, make_offered_htlc
from .lnutil import HTLC_TIMEOUT_WEIGHT, HTLC_SUCCESS_WEIGHT
from .lnutil import funding_output_script, LOCAL, REMOTE, HTLCOwner, make_closing_tx, make_commitment_outputs
from .lnutil import ScriptHtlc, PaymentFailure, calc_onchain_fees, RemoteMisbehaving, make_htlc_output_witness_script
from .transaction import Transaction
from .lnsweep import (create_sweeptxs_for_our_latest_ctx, create_sweeptxs_for_their_latest_ctx,
create_sweeptxs_for_their_just_revoked_ctx)
class ChannelJsonEncoder(json.JSONEncoder):
def default(self, o):
if isinstance(o, bytes):
return binascii.hexlify(o).decode("ascii")
if isinstance(o, RevocationStore):
return o.serialize()
if isinstance(o, set):
return list(o)
return super().default(o)
RevokeAndAck = namedtuple("RevokeAndAck", ["per_commitment_secret", "next_per_commitment_point"])
class FeeUpdateProgress(Enum):
FUNDEE_SIGNED = auto()
FUNDEE_ACKED = auto()
FUNDER_SIGNED = auto()
FUNDEE_SIGNED = FeeUpdateProgress.FUNDEE_SIGNED
FUNDEE_ACKED = FeeUpdateProgress.FUNDEE_ACKED
FUNDER_SIGNED = FeeUpdateProgress.FUNDER_SIGNED
class FeeUpdate(defaultdict):
def __init__(self, chan, rate):
super().__init__(lambda: False)
self.rate = rate
self.chan = chan
def pending_feerate(self, subject):
if self[FUNDEE_ACKED]:
return self.rate
if subject == REMOTE and self.chan.constraints.is_initiator:
return self.rate
if subject == LOCAL and not self.chan.constraints.is_initiator:
return self.rate
# implicit return None
class UpdateAddHtlc(namedtuple('UpdateAddHtlc', ['amount_msat', 'payment_hash', 'cltv_expiry', 'htlc_id'])):
"""
This whole class body is so that if you pass a hex-string as payment_hash,
it is decoded to bytes. Bytes can't be saved to disk, so we save hex-strings.
"""
__slots__ = ()
def __new__(cls, *args, **kwargs):
if len(args) > 0:
args = list(args)
if type(args[1]) is str:
args[1] = bfh(args[1])
return super().__new__(cls, *args)
if type(kwargs['payment_hash']) is str:
kwargs['payment_hash'] = bfh(kwargs['payment_hash'])
return super().__new__(cls, **kwargs)
def decodeAll(d, local):
for k, v in d.items():
if k == 'revocation_store':
yield (k, RevocationStore.from_json_obj(v))
elif k.endswith("_basepoint") or k.endswith("_key"):
if local:
yield (k, Keypair(**dict(decodeAll(v, local))))
else:
yield (k, OnlyPubkeyKeypair(**dict(decodeAll(v, local))))
elif k in ["node_id", "channel_id", "short_channel_id", "pubkey", "privkey", "current_per_commitment_point", "next_per_commitment_point", "per_commitment_secret_seed", "current_commitment_signature", "current_htlc_signatures"] and v is not None:
yield (k, binascii.unhexlify(v))
else:
yield (k, v)
def htlcsum(htlcs):
return sum([x.amount_msat for x in htlcs])
# following two functions are used because json
# doesn't store int keys and byte string values
def str_bytes_dict_from_save(x):
return {int(k): bfh(v) for k,v in x.items()}
def str_bytes_dict_to_save(x):
return {str(k): bh2u(v) for k, v in x.items()}
class HtlcChanges(NamedTuple):
# ints are htlc ids
adds: Dict[int, UpdateAddHtlc]
settles: Set[int]
fails: Set[int]
locked_in: Set[int]
@staticmethod
def new():
"""
Since we can't use default arguments for these types (they would be shared among instances)
"""
return HtlcChanges({}, set(), set(), set())
class Channel(PrintError):
def diagnostic_name(self):
if self.name:
return str(self.name)
try:
return f"lnchan_{bh2u(self.channel_id[-4:])}"
except:
return super().diagnostic_name()
def __init__(self, state, name = None, payment_completed : Optional[Callable[[HTLCOwner, UpdateAddHtlc, bytes], None]] = None):
self.preimages = {}
if not payment_completed:
payment_completed = lambda this, x, y, z: None
self.payment_completed = payment_completed
assert 'local_state' not in state
self.config = {}
self.config[LOCAL] = state["local_config"]
if type(self.config[LOCAL]) is not LocalConfig:
conf = dict(decodeAll(self.config[LOCAL], True))
self.config[LOCAL] = LocalConfig(**conf)
assert type(self.config[LOCAL].htlc_basepoint.privkey) is bytes
self.config[REMOTE] = state["remote_config"]
if type(self.config[REMOTE]) is not RemoteConfig:
conf = dict(decodeAll(self.config[REMOTE], False))
self.config[REMOTE] = RemoteConfig(**conf)
assert type(self.config[REMOTE].htlc_basepoint.pubkey) is bytes
self.channel_id = bfh(state["channel_id"]) if type(state["channel_id"]) not in (bytes, type(None)) else state["channel_id"]
self.constraints = ChannelConstraints(**state["constraints"]) if type(state["constraints"]) is not ChannelConstraints else state["constraints"]
self.funding_outpoint = Outpoint(**dict(decodeAll(state["funding_outpoint"], False))) if type(state["funding_outpoint"]) is not Outpoint else state["funding_outpoint"]
self.node_id = bfh(state["node_id"]) if type(state["node_id"]) not in (bytes, type(None)) else state["node_id"]
self.short_channel_id = bfh(state["short_channel_id"]) if type(state["short_channel_id"]) not in (bytes, type(None)) else state["short_channel_id"]
self.short_channel_id_predicted = self.short_channel_id
self.onion_keys = str_bytes_dict_from_save(state.get('onion_keys', {}))
# FIXME this is a tx serialised in the custom electrum partial tx format.
# we should not persist txns in this format. we should persist htlcs, and be able to derive
# any past commitment transaction and use that instead; until then...
self.remote_commitment_to_be_revoked = Transaction(state["remote_commitment_to_be_revoked"])
self.log = {LOCAL: HtlcChanges.new(), REMOTE: HtlcChanges.new()}
for strname, subject in [('remote_log', REMOTE), ('local_log', LOCAL)]:
if strname not in state: continue
for y in state[strname]:
htlc = UpdateAddHtlc(**y)
self.log[subject].adds[htlc.htlc_id] = htlc
self.name = name
self.pending_fee = None
self.local_commitment = self.pending_commitment(LOCAL)
self.remote_commitment = self.pending_commitment(REMOTE)
self._is_funding_txo_spent = None # "don't know"
self._state = None
if state.get('force_closed', False):
self.set_state('FORCE_CLOSING')
else:
self.set_state('DISCONNECTED')
self.lnwatcher = None
self.settled = {LOCAL: state.get('settled_local', []), REMOTE: state.get('settled_remote', [])}
for sub in (LOCAL, REMOTE):
self.log[sub].locked_in.update(self.log[sub].adds.keys())
def set_state(self, state: str):
if self._state == 'FORCE_CLOSING':
assert state == 'FORCE_CLOSING', 'new state was not FORCE_CLOSING: ' + state
self._state = state
def get_state(self):
return self._state
def _check_can_pay(self, amount_msat: int) -> None:
if self.get_state() != 'OPEN':
raise PaymentFailure('Channel not open')
if self.available_to_spend(LOCAL) < amount_msat:
raise PaymentFailure(f'Not enough local balance. Have: {self.available_to_spend(LOCAL)}, Need: {amount_msat}')
if len(self.htlcs(LOCAL, only_pending=True)) + 1 > self.config[REMOTE].max_accepted_htlcs:
raise PaymentFailure('Too many HTLCs already in channel')
current_htlc_sum = htlcsum(self.htlcs(LOCAL, only_pending=True))
if current_htlc_sum + amount_msat > self.config[REMOTE].max_htlc_value_in_flight_msat:
raise PaymentFailure(f'HTLC value sum (sum of pending htlcs: {current_htlc_sum/1000} sat plus new htlc: {amount_msat/1000} sat) would exceed max allowed: {self.config[REMOTE].max_htlc_value_in_flight_msat/1000} sat')
if amount_msat <= 0: # FIXME htlc_minimum_msat
raise PaymentFailure(f'HTLC value too small: {amount_msat} msat')
def can_pay(self, amount_msat):
try:
self._check_can_pay(amount_msat)
except PaymentFailure:
return False
return True
def set_funding_txo_spentness(self, is_spent: bool):
assert isinstance(is_spent, bool)
self._is_funding_txo_spent = is_spent
def should_try_to_reestablish_peer(self) -> bool:
return self._is_funding_txo_spent is False and self._state == 'DISCONNECTED'
def get_funding_address(self):
script = funding_output_script(self.config[LOCAL], self.config[REMOTE])
return redeem_script_to_address('p2wsh', script)
def add_htlc(self, htlc):
"""
AddHTLC adds an HTLC to the state machine's local update log. This method
should be called when preparing to send an outgoing HTLC.
This docstring is from LND.
"""
assert type(htlc) is dict
self._check_can_pay(htlc['amount_msat'])
htlc = UpdateAddHtlc(**htlc, htlc_id=self.config[LOCAL].next_htlc_id)
self.log[LOCAL].adds[htlc.htlc_id] = htlc
self.print_error("add_htlc")
self.config[LOCAL]=self.config[LOCAL]._replace(next_htlc_id=htlc.htlc_id + 1)
return htlc.htlc_id
def receive_htlc(self, htlc):
"""
ReceiveHTLC adds an HTLC to the state machine's remote update log. This
method should be called in response to receiving a new HTLC from the remote
party.
This docstring is from LND.
"""
assert type(htlc) is dict
htlc = UpdateAddHtlc(**htlc, htlc_id = self.config[REMOTE].next_htlc_id)
if self.available_to_spend(REMOTE) < htlc.amount_msat:
raise RemoteMisbehaving('Remote dipped below channel reserve.' +\
f' Available at remote: {self.available_to_spend(REMOTE)},' +\
f' HTLC amount: {htlc.amount_msat}')
adds = self.log[REMOTE].adds
adds[htlc.htlc_id] = htlc
self.print_error("receive_htlc")
self.config[REMOTE]=self.config[REMOTE]._replace(next_htlc_id=htlc.htlc_id + 1)
return htlc.htlc_id
def sign_next_commitment(self):
"""
SignNextCommitment signs a new commitment which includes any previous
unsettled HTLCs, any new HTLCs, and any modifications to prior HTLCs
committed in previous commitment updates.
The first return parameter is the signature for the commitment transaction
itself, while the second parameter is are all HTLC signatures concatenated.
any). The HTLC signatures are sorted according to the BIP 69 order of the
HTLC's on the commitment transaction.
This docstring was adapted from LND.
"""
self.print_error("sign_next_commitment")
old_logs = dict(self.lock_in_htlc_changes(LOCAL))
pending_remote_commitment = self.pending_commitment(REMOTE)
sig_64 = sign_and_get_sig_string(pending_remote_commitment, self.config[LOCAL], self.config[REMOTE])
their_remote_htlc_privkey_number = derive_privkey(
int.from_bytes(self.config[LOCAL].htlc_basepoint.privkey, 'big'),
self.config[REMOTE].next_per_commitment_point)
their_remote_htlc_privkey = their_remote_htlc_privkey_number.to_bytes(32, 'big')
for_us = False
htlcsigs = []
for we_receive, htlcs in zip([True, False], [self.included_htlcs(REMOTE, REMOTE), self.included_htlcs(REMOTE, LOCAL)]):
for htlc in htlcs:
_script, htlc_tx = make_htlc_tx_with_open_channel(chan=self,
pcp=self.config[REMOTE].next_per_commitment_point,
for_us=for_us,
we_receive=we_receive,
commit=pending_remote_commitment,
htlc=htlc)
sig = bfh(htlc_tx.sign_txin(0, their_remote_htlc_privkey))
htlc_sig = ecc.sig_string_from_der_sig(sig[:-1])
htlc_output_idx = htlc_tx.inputs()[0]['prevout_n']
htlcsigs.append((htlc_output_idx, htlc_sig))
htlcsigs.sort()
htlcsigs = [x[1] for x in htlcsigs]
self.process_new_offchain_ctx(pending_remote_commitment, ours=False)
# we can't know if this message arrives.
# since we shouldn't actually throw away
# failed htlcs yet (or mark htlc locked in),
# roll back the changes that were made
self.log = old_logs
return sig_64, htlcsigs
def lock_in_htlc_changes(self, subject):
for sub in (LOCAL, REMOTE):
log = self.log[sub]
yield (sub, deepcopy(log))
for htlc_id in log.fails:
log.adds.pop(htlc_id)
log.fails.clear()
self.log[subject].locked_in.update(self.log[subject].adds.keys())
def receive_new_commitment(self, sig, htlc_sigs):
"""
ReceiveNewCommitment process a signature for a new commitment state sent by
the remote party. This method should be called in response to the
remote party initiating a new change, or when the remote party sends a
signature fully accepting a new state we've initiated. If we are able to
successfully validate the signature, then the generated commitment is added
to our local commitment chain. Once we send a revocation for our prior
state, then this newly added commitment becomes our current accepted channel
state.
This docstring is from LND.
"""
self.print_error("receive_new_commitment")
for _ in self.lock_in_htlc_changes(REMOTE): pass
assert len(htlc_sigs) == 0 or type(htlc_sigs[0]) is bytes
pending_local_commitment = self.pending_commitment(LOCAL)
preimage_hex = pending_local_commitment.serialize_preimage(0)
pre_hash = sha256d(bfh(preimage_hex))
if not ecc.verify_signature(self.config[REMOTE].multisig_key.pubkey, sig, pre_hash):
raise Exception('failed verifying signature of our updated commitment transaction: ' + bh2u(sig) + ' preimage is ' + preimage_hex)
htlc_sigs_string = b''.join(htlc_sigs)
htlc_sigs = htlc_sigs[:] # copy cause we will delete now
for htlcs, we_receive in [(self.included_htlcs(LOCAL, REMOTE), True), (self.included_htlcs(LOCAL, LOCAL), False)]:
for htlc in htlcs:
idx = self.verify_htlc(htlc, htlc_sigs, we_receive)
del htlc_sigs[idx]
if len(htlc_sigs) != 0: # all sigs should have been popped above
raise Exception('failed verifying HTLC signatures: invalid amount of correct signatures')
self.config[LOCAL]=self.config[LOCAL]._replace(
current_commitment_signature=sig,
current_htlc_signatures=htlc_sigs_string)
if self.pending_fee is not None:
if not self.constraints.is_initiator:
self.pending_fee[FUNDEE_SIGNED] = True
if self.constraints.is_initiator and self.pending_fee[FUNDEE_ACKED]:
self.pending_fee[FUNDER_SIGNED] = True
self.process_new_offchain_ctx(pending_local_commitment, ours=True)
def verify_htlc(self, htlc: UpdateAddHtlc, htlc_sigs: Sequence[bytes], we_receive: bool) -> int:
_, this_point, _ = self.points()
_script, htlc_tx = make_htlc_tx_with_open_channel(chan=self,
pcp=this_point,
for_us=True,
we_receive=we_receive,
commit=self.pending_commitment(LOCAL),
htlc=htlc)
pre_hash = sha256d(bfh(htlc_tx.serialize_preimage(0)))
remote_htlc_pubkey = derive_pubkey(self.config[REMOTE].htlc_basepoint.pubkey, this_point)
for idx, sig in enumerate(htlc_sigs):
if ecc.verify_signature(remote_htlc_pubkey, sig, pre_hash):
return idx
else:
raise Exception(f'failed verifying HTLC signatures: {htlc}')
def get_remote_htlc_sig_for_htlc(self, htlc: UpdateAddHtlc, we_receive: bool) -> bytes:
data = self.config[LOCAL].current_htlc_signatures
htlc_sigs = [data[i:i + 64] for i in range(0, len(data), 64)]
idx = self.verify_htlc(htlc, htlc_sigs, we_receive=we_receive)
remote_htlc_sig = ecc.der_sig_from_sig_string(htlc_sigs[idx]) + b'\x01'
return remote_htlc_sig
def revoke_current_commitment(self):
self.print_error("revoke_current_commitment")
last_secret, this_point, next_point = self.points()
new_feerate = self.constraints.feerate
if self.pending_fee is not None:
if not self.constraints.is_initiator and self.pending_fee[FUNDEE_SIGNED]:
new_feerate = self.pending_fee.rate
self.pending_fee = None
print("FEERATE CHANGE COMPLETE (non-initiator)")
if self.constraints.is_initiator and self.pending_fee[FUNDER_SIGNED]:
new_feerate = self.pending_fee.rate
self.pending_fee = None
print("FEERATE CHANGE COMPLETE (initiator)")
self.config[LOCAL]=self.config[LOCAL]._replace(
ctn=self.config[LOCAL].ctn + 1,
)
self.constraints=self.constraints._replace(
feerate=new_feerate
)
self.local_commitment = self.pending_commitment(LOCAL)
return RevokeAndAck(last_secret, next_point), "current htlcs"
def points(self):
last_small_num = self.config[LOCAL].ctn
this_small_num = last_small_num + 1
next_small_num = last_small_num + 2
last_secret = get_per_commitment_secret_from_seed(self.config[LOCAL].per_commitment_secret_seed, RevocationStore.START_INDEX - last_small_num)
this_secret = get_per_commitment_secret_from_seed(self.config[LOCAL].per_commitment_secret_seed, RevocationStore.START_INDEX - this_small_num)
this_point = secret_to_pubkey(int.from_bytes(this_secret, 'big'))
next_secret = get_per_commitment_secret_from_seed(self.config[LOCAL].per_commitment_secret_seed, RevocationStore.START_INDEX - next_small_num)
next_point = secret_to_pubkey(int.from_bytes(next_secret, 'big'))
return last_secret, this_point, next_point
# TODO don't presign txns for non-breach close
def process_new_offchain_ctx(self, ctx: 'Transaction', ours: bool):
if not self.lnwatcher:
return
outpoint = self.funding_outpoint.to_str()
if ours:
encumbered_sweeptxs = create_sweeptxs_for_our_latest_ctx(self, ctx, self.sweep_address)
else:
encumbered_sweeptxs = create_sweeptxs_for_their_latest_ctx(self, ctx, self.sweep_address)
for prev_txid, encumbered_tx in encumbered_sweeptxs:
if prev_txid is None:
prev_txid = ctx.txid()
if encumbered_tx is not None:
self.lnwatcher.add_sweep_tx(outpoint, prev_txid, encumbered_tx.to_json())
def process_new_revocation_secret(self, per_commitment_secret: bytes):
if not self.lnwatcher:
return
outpoint = self.funding_outpoint.to_str()
ctx = self.remote_commitment_to_be_revoked # FIXME can't we just reconstruct it?
encumbered_sweeptxs = create_sweeptxs_for_their_just_revoked_ctx(self, ctx, per_commitment_secret, self.sweep_address)
for prev_txid, encumbered_tx in encumbered_sweeptxs:
if prev_txid is None:
prev_txid = ctx.txid()
if encumbered_tx is not None:
self.lnwatcher.add_sweep_tx(outpoint, prev_txid, encumbered_tx.to_json())
def receive_revocation(self, revocation) -> Tuple[int, int]:
self.print_error("receive_revocation")
old_logs = dict(self.lock_in_htlc_changes(LOCAL))
cur_point = self.config[REMOTE].current_per_commitment_point
derived_point = ecc.ECPrivkey(revocation.per_commitment_secret).get_public_key_bytes(compressed=True)
if cur_point != derived_point:
self.log = old_logs
raise Exception('revoked secret not for current point')
# FIXME not sure this is correct... but it seems to work
# if there are update_add_htlc msgs between commitment_signed and rev_ack,
# this might break
prev_remote_commitment = self.pending_commitment(REMOTE)
self.config[REMOTE].revocation_store.add_next_entry(revocation.per_commitment_secret)
self.process_new_revocation_secret(revocation.per_commitment_secret)
##### start applying fee/htlc changes
if self.pending_fee is not None:
if not self.constraints.is_initiator:
self.pending_fee[FUNDEE_SIGNED] = True
if self.constraints.is_initiator and self.pending_fee[FUNDEE_ACKED]:
self.pending_fee[FUNDER_SIGNED] = True
def mark_settled(subject):
"""
find pending settlements for subject (LOCAL or REMOTE) and mark them settled, return value of settled htlcs
"""
old_amount = htlcsum(self.htlcs(subject, False))
for htlc_id in self.log[subject].settles:
adds = self.log[subject].adds
htlc = adds.pop(htlc_id)
self.settled[subject].append(htlc.amount_msat)
if subject == LOCAL:
preimage = self.preimages.pop(htlc_id)
else:
preimage = None
self.payment_completed(self, subject, htlc, preimage)
self.log[subject].settles.clear()
return old_amount - htlcsum(self.htlcs(subject, False))
sent_this_batch = mark_settled(LOCAL)
received_this_batch = mark_settled(REMOTE)
next_point = self.config[REMOTE].next_per_commitment_point
print("RECEIVED", received_this_batch)
print("SENT", sent_this_batch)
self.config[REMOTE]=self.config[REMOTE]._replace(
ctn=self.config[REMOTE].ctn + 1,
current_per_commitment_point=next_point,
next_per_commitment_point=revocation.next_per_commitment_point,
amount_msat=self.config[REMOTE].amount_msat + (sent_this_batch - received_this_batch)
)
self.config[LOCAL]=self.config[LOCAL]._replace(
amount_msat = self.config[LOCAL].amount_msat + (received_this_batch - sent_this_batch)
)
if self.pending_fee is not None:
if self.constraints.is_initiator:
self.pending_fee[FUNDEE_ACKED] = True
self.local_commitment = self.pending_commitment(LOCAL)
self.remote_commitment = self.pending_commitment(REMOTE)
self.remote_commitment_to_be_revoked = prev_remote_commitment
return received_this_batch, sent_this_batch
def balance(self, subject):
"""
This balance in mSAT is not including reserve and fees.
So a node cannot actually use it's whole balance.
But this number is simple, since it is derived simply
from the initial balance, and the value of settled HTLCs.
Note that it does not decrease once an HTLC is added,
failed or fulfilled, since the balance change is only
commited to later when the respective commitment
transaction as been revoked.
"""
initial = self.config[subject].initial_msat
initial -= sum(self.settled[subject])
initial += sum(self.settled[-subject])
assert initial == self.config[subject].amount_msat
return initial
def balance_minus_outgoing_htlcs(self, subject):
"""
This balance in mSAT, which includes the value of
pending outgoing HTLCs, is used in the UI.
"""
return self.balance(subject)\
- htlcsum(self.log[subject].adds.values())
def available_to_spend(self, subject):
"""
This balance in mSAT, while technically correct, can
not be used in the UI cause it fluctuates (commit fee)
"""
return self.balance_minus_outgoing_htlcs(subject)\
- htlcsum(self.log[subject].adds.values())\
- self.config[-subject].reserve_sat * 1000\
- calc_onchain_fees(
# TODO should we include a potential new htlc, when we are called from receive_htlc?
len(list(self.included_htlcs(subject, LOCAL)) + list(self.included_htlcs(subject, REMOTE))),
self.pending_feerate(subject),
True, # for_us
self.constraints.is_initiator,
)[subject]
def amounts(self):
remote_settled= htlcsum(self.htlcs(REMOTE, False))
local_settled= htlcsum(self.htlcs(LOCAL, False))
unsettled_local = htlcsum(self.htlcs(LOCAL, True))
unsettled_remote = htlcsum(self.htlcs(REMOTE, True))
remote_msat = self.config[REMOTE].amount_msat -\
unsettled_remote + local_settled - remote_settled
local_msat = self.config[LOCAL].amount_msat -\
unsettled_local + remote_settled - local_settled
return remote_msat, local_msat
def included_htlcs(self, subject, htlc_initiator, only_pending=True):
"""
return filter of non-dust htlcs for subjects commitment transaction, initiated by given party
"""
feerate = self.pending_feerate(subject)
conf = self.config[subject]
weight = HTLC_SUCCESS_WEIGHT if subject != htlc_initiator else HTLC_TIMEOUT_WEIGHT
htlcs = self.htlcs(htlc_initiator, only_pending=only_pending)
fee_for_htlc = lambda htlc: htlc.amount_msat // 1000 - (weight * feerate // 1000)
return filter(lambda htlc: fee_for_htlc(htlc) >= conf.dust_limit_sat, htlcs)
def pending_feerate(self, subject):
candidate = self.constraints.feerate
if self.pending_fee is not None:
x = self.pending_fee.pending_feerate(subject)
if x is not None:
candidate = x
return candidate
def pending_commitment(self, subject):
this_point = self.config[REMOTE].next_per_commitment_point if subject == REMOTE else self.points()[1]
return self.make_commitment(subject, this_point)
def total_msat(self, sub):
return sum(self.settled[sub])
def htlcs(self, subject, only_pending):
"""
only_pending: require the htlc's settlement to be pending (needs additional signatures/acks)
sets returned with True and False are disjunct
only_pending true:
skipped if settled or failed
<=>
included if not settled and not failed
only_pending false:
skipped if not (settled or failed)
<=>
included if not not (settled or failed)
included if settled or failed
"""
update_log = self.log[subject]
res = []
for htlc in update_log.adds.values():
locked_in = htlc.htlc_id in update_log.locked_in
settled = htlc.htlc_id in update_log.settles
failed = htlc.htlc_id in update_log.fails
if not locked_in:
continue
if only_pending == (settled or failed):
continue
res.append(htlc)
return res
def settle_htlc(self, preimage, htlc_id):
"""
SettleHTLC attempts to settle an existing outstanding received HTLC.
"""
self.print_error("settle_htlc")
log = self.log[REMOTE]
htlc = log.adds[htlc_id]
assert htlc.payment_hash == sha256(preimage)
assert htlc_id not in log.settles
log.settles.add(htlc_id)
# not saving preimage because it's already saved in LNWorker.invoices
def receive_htlc_settle(self, preimage, htlc_id):
self.print_error("receive_htlc_settle")
log = self.log[LOCAL]
htlc = log.adds[htlc_id]
assert htlc.payment_hash == sha256(preimage)
assert htlc_id not in log.settles
self.preimages[htlc_id] = preimage
log.settles.add(htlc_id)
# we don't save the preimage because we don't need to forward it anyway
def fail_htlc(self, htlc_id):
self.print_error("fail_htlc")
log = self.log[REMOTE]
assert htlc_id not in log.fails
log.fails.add(htlc_id)
def receive_fail_htlc(self, htlc_id):
self.print_error("receive_fail_htlc")
log = self.log[LOCAL]
assert htlc_id not in log.fails
log.fails.add(htlc_id)
@property
def current_height(self):
return {LOCAL: self.config[LOCAL].ctn, REMOTE: self.config[REMOTE].ctn}
def pending_local_fee(self):
return self.constraints.capacity - sum(x[2] for x in self.pending_commitment(LOCAL).outputs())
def update_fee(self, feerate, initiator):
if self.constraints.is_initiator != initiator:
raise Exception("Cannot update_fee: wrong initiator", initiator)
if self.pending_fee is not None:
raise Exception("a fee update is already in progress")
self.pending_fee = FeeUpdate(self, rate=feerate)
def remove_uncommitted_htlcs_from_log(self, subject):
"""
returns
- the htlcs with uncommited (not locked in) htlcs removed
- a list of htlc_ids that were removed
"""
removed = []
htlcs = []
log = self.log[subject]
for i in log.adds.values():
locked_in = i.htlc_id in log.locked_in
if locked_in:
htlcs.append(i._asdict())
else:
removed.append(i.htlc_id)
return htlcs, removed
def to_save(self):
# need to forget about uncommited htlcs
# since we must assume they don't know about it,
# if it was not acked
remote_filtered, remote_removed = self.remove_uncommitted_htlcs_from_log(REMOTE)
local_filtered, local_removed = self.remove_uncommitted_htlcs_from_log(LOCAL)
to_save = {
"local_config": self.config[LOCAL],
"remote_config": self.config[REMOTE],
"channel_id": self.channel_id,
"short_channel_id": self.short_channel_id,
"constraints": self.constraints,
"funding_outpoint": self.funding_outpoint,
"node_id": self.node_id,
"remote_commitment_to_be_revoked": str(self.remote_commitment_to_be_revoked),
"remote_log": remote_filtered,
"local_log": local_filtered,
"onion_keys": str_bytes_dict_to_save(self.onion_keys),
"settled_local": self.settled[LOCAL],
"settled_remote": self.settled[REMOTE],
"force_closed": self.get_state() == 'FORCE_CLOSING',
}
# htlcs number must be monotonically increasing,
# so we have to decrease the counter
if len(remote_removed) != 0:
assert min(remote_removed) < to_save['remote_config'].next_htlc_id
to_save['remote_config'] = to_save['remote_config']._replace(next_htlc_id = min(remote_removed))
if len(local_removed) != 0:
assert min(local_removed) < to_save['local_config'].next_htlc_id
to_save['local_config'] = to_save['local_config']._replace(next_htlc_id = min(local_removed))
return to_save
def serialize(self):
namedtuples_to_dict = lambda v: {i: j._asdict() if isinstance(j, tuple) else j for i, j in v._asdict().items()}
serialized_channel = {}
to_save_ref = self.to_save()
for k, v in to_save_ref.items():
if isinstance(v, tuple):
serialized_channel[k] = namedtuples_to_dict(v)
else:
serialized_channel[k] = v
dumped = ChannelJsonEncoder().encode(serialized_channel)
roundtripped = json.loads(dumped)
reconstructed = Channel(roundtripped)
to_save_new = reconstructed.to_save()
if to_save_new != to_save_ref:
from pprint import PrettyPrinter
pp = PrettyPrinter(indent=168)
try:
from deepdiff import DeepDiff
except ImportError:
raise Exception("Channels did not roundtrip serialization without changes:\n" + pp.pformat(to_save_ref) + "\n" + pp.pformat(to_save_new))
else:
raise Exception("Channels did not roundtrip serialization without changes:\n" + pp.pformat(DeepDiff(to_save_ref, to_save_new)))
return roundtripped
def __str__(self):
return str(self.serialize())
def make_commitment(self, subject, this_point) -> Transaction:
remote_msat, local_msat = self.amounts()
assert local_msat >= 0, local_msat
assert remote_msat >= 0, remote_msat
this_config = self.config[subject]
other_config = self.config[-subject]
other_htlc_pubkey = derive_pubkey(other_config.htlc_basepoint.pubkey, this_point)
this_htlc_pubkey = derive_pubkey(this_config.htlc_basepoint.pubkey, this_point)
other_revocation_pubkey = derive_blinded_pubkey(other_config.revocation_basepoint.pubkey, this_point)
htlcs = [] # type: List[ScriptHtlc]
def append_htlc(htlc: UpdateAddHtlc, is_received_htlc: bool):
htlcs.append(ScriptHtlc(make_htlc_output_witness_script(
is_received_htlc=is_received_htlc,
remote_revocation_pubkey=other_revocation_pubkey,
remote_htlc_pubkey=other_htlc_pubkey,
local_htlc_pubkey=this_htlc_pubkey,
payment_hash=htlc.payment_hash,
cltv_expiry=htlc.cltv_expiry), htlc))
for htlc in self.included_htlcs(subject, -subject):
append_htlc(htlc, is_received_htlc=True)
for htlc in self.included_htlcs(subject, subject):
append_htlc(htlc, is_received_htlc=False)
if subject != LOCAL:
remote_msat, local_msat = local_msat, remote_msat
payment_pubkey = derive_pubkey(other_config.payment_basepoint.pubkey, this_point)
return make_commitment(
self.config[subject].ctn + 1,
this_config.multisig_key.pubkey,
other_config.multisig_key.pubkey,
payment_pubkey,
self.config[LOCAL if self.constraints.is_initiator else REMOTE].payment_basepoint.pubkey,
self.config[LOCAL if not self.constraints.is_initiator else REMOTE].payment_basepoint.pubkey,
other_revocation_pubkey,
derive_pubkey(this_config.delayed_basepoint.pubkey, this_point),
other_config.to_self_delay,
*self.funding_outpoint,
self.constraints.capacity,
local_msat,
remote_msat,
this_config.dust_limit_sat,
calc_onchain_fees(
len(htlcs),
self.pending_feerate(subject),
subject == LOCAL,
self.constraints.is_initiator,
),
htlcs=htlcs)
def get_local_index(self):
return int(self.config[LOCAL].multisig_key.pubkey < self.config[REMOTE].multisig_key.pubkey)
def make_closing_tx(self, local_script: bytes, remote_script: bytes,
fee_sat: int) -> Tuple[bytes, int, str]:
""" cooperative close """
_, outputs = make_commitment_outputs({
LOCAL: fee_sat * 1000 if self.constraints.is_initiator else 0,
REMOTE: fee_sat * 1000 if not self.constraints.is_initiator else 0,
},
self.config[LOCAL].amount_msat,
self.config[REMOTE].amount_msat,
(TYPE_SCRIPT, bh2u(local_script)),
(TYPE_SCRIPT, bh2u(remote_script)),
[], self.config[LOCAL].dust_limit_sat)
closing_tx = make_closing_tx(self.config[LOCAL].multisig_key.pubkey,
self.config[REMOTE].multisig_key.pubkey,
funding_txid=self.funding_outpoint.txid,
funding_pos=self.funding_outpoint.output_index,
funding_sat=self.constraints.capacity,
outputs=outputs)
der_sig = bfh(closing_tx.sign_txin(0, self.config[LOCAL].multisig_key.privkey))
sig = ecc.sig_string_from_der_sig(der_sig[:-1])
return sig, closing_tx
def force_close_tx(self):
# local_commitment always gives back the next expected local_commitment,
# but in this case, we want the current one. So substract one ctn number
old_local_state = self.config[LOCAL]
self.config[LOCAL]=self.config[LOCAL]._replace(ctn=self.config[LOCAL].ctn - 1)
tx = self.pending_commitment(LOCAL)
self.config[LOCAL] = old_local_state
tx.sign({bh2u(self.config[LOCAL].multisig_key.pubkey): (self.config[LOCAL].multisig_key.privkey, True)})
remote_sig = self.config[LOCAL].current_commitment_signature
remote_sig = ecc.der_sig_from_sig_string(remote_sig) + b"\x01"
none_idx = tx._inputs[0]["signatures"].index(None)
tx.add_signature_to_txin(0, none_idx, bh2u(remote_sig))
assert tx.is_complete()
return tx
def included_htlcs_in_their_latest_ctxs(self, htlc_initiator) -> Dict[int, List[UpdateAddHtlc]]:
""" A map from commitment number to list of HTLCs in
their latest two commitment transactions.
The oldest might have been revoked. """
old_htlcs = list(self.included_htlcs(REMOTE, htlc_initiator, only_pending=False))
old_logs = dict(self.lock_in_htlc_changes(LOCAL))
new_htlcs = list(self.included_htlcs(REMOTE, htlc_initiator))
self.log = old_logs
return {self.config[REMOTE].ctn: old_htlcs,
self.config[REMOTE].ctn+1: new_htlcs, }
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