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electrum/electrum/lnchannel.py

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# Copyright (C) 2018 The Electrum 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.
import os
from collections import namedtuple, defaultdict
import binascii
import json
from enum import IntEnum
from typing import (Optional, Dict, List, Tuple, NamedTuple, Set, Callable,
Iterable, Sequence, TYPE_CHECKING, Iterator, Union)
import time
import threading
from abc import ABC, abstractmethod
import itertools
from aiorpcx import NetAddress
import attr
from . import ecc
from . import constants, util
from .util import bfh, bh2u, chunks, TxMinedInfo
from .invoices import PR_PAID
from .bitcoin import redeem_script_to_address
from .crypto import sha256, sha256d
from .transaction import Transaction, PartialTransaction, TxInput
from .logging import Logger
from .lnonion import decode_onion_error, OnionFailureCode, OnionRoutingFailureMessage
from . import lnutil
from .lnutil import (Outpoint, LocalConfig, RemoteConfig, Keypair, OnlyPubkeyKeypair, ChannelConstraints,
get_per_commitment_secret_from_seed, secret_to_pubkey, derive_privkey, make_closing_tx,
sign_and_get_sig_string, RevocationStore, derive_blinded_pubkey, Direction, derive_pubkey,
make_htlc_tx_with_open_channel, make_commitment, make_received_htlc, make_offered_htlc,
HTLC_TIMEOUT_WEIGHT, HTLC_SUCCESS_WEIGHT, extract_ctn_from_tx_and_chan, UpdateAddHtlc,
funding_output_script, SENT, RECEIVED, LOCAL, REMOTE, HTLCOwner, make_commitment_outputs,
ScriptHtlc, PaymentFailure, calc_fees_for_commitment_tx, RemoteMisbehaving, make_htlc_output_witness_script,
ShortChannelID, map_htlcs_to_ctx_output_idxs, LNPeerAddr,
LN_MAX_HTLC_VALUE_MSAT, fee_for_htlc_output, offered_htlc_trim_threshold_sat,
received_htlc_trim_threshold_sat, make_commitment_output_to_remote_address)
from .lnsweep import create_sweeptxs_for_our_ctx, create_sweeptxs_for_their_ctx
from .lnsweep import create_sweeptx_for_their_revoked_htlc, SweepInfo
from .lnhtlc import HTLCManager
from .lnmsg import encode_msg, decode_msg
from .address_synchronizer import TX_HEIGHT_LOCAL
from .lnutil import CHANNEL_OPENING_TIMEOUT
from .lnutil import ChannelBackupStorage
from .lnutil import format_short_channel_id
if TYPE_CHECKING:
from .lnworker import LNWallet
from .json_db import StoredDict
from .lnrouter import RouteEdge
# lightning channel states
# Note: these states are persisted by name (for a given channel) in the wallet file,
# so consider doing a wallet db upgrade when changing them.
class ChannelState(IntEnum):
PREOPENING = 0 # Initial negotiation. Channel will not be reestablished
OPENING = 1 # Channel will be reestablished. (per BOLT2)
# - Funding node: has received funding_signed (can broadcast the funding tx)
# - Non-funding node: has sent the funding_signed message.
FUNDED = 2 # Funding tx was mined (requires min_depth and tx verification)
OPEN = 3 # both parties have sent funding_locked
SHUTDOWN = 4 # shutdown has been sent.
CLOSING = 5 # closing negotiation done. we have a fully signed tx.
FORCE_CLOSING = 6 # we force-closed, and closing tx is unconfirmed. Note that if the
# remote force-closes then we remain OPEN until it gets mined -
# the server could be lying to us with a fake tx.
CLOSED = 7 # closing tx has been mined
REDEEMED = 8 # we can stop watching
class PeerState(IntEnum):
DISCONNECTED = 0
REESTABLISHING = 1
GOOD = 2
BAD = 3
cs = ChannelState
state_transitions = [
(cs.PREOPENING, cs.OPENING),
(cs.OPENING, cs.FUNDED),
(cs.FUNDED, cs.OPEN),
(cs.OPENING, cs.SHUTDOWN),
(cs.FUNDED, cs.SHUTDOWN),
(cs.OPEN, cs.SHUTDOWN),
(cs.SHUTDOWN, cs.SHUTDOWN), # if we reestablish
(cs.SHUTDOWN, cs.CLOSING),
(cs.CLOSING, cs.CLOSING),
# we can force close almost any time
(cs.OPENING, cs.FORCE_CLOSING),
(cs.FUNDED, cs.FORCE_CLOSING),
(cs.OPEN, cs.FORCE_CLOSING),
(cs.SHUTDOWN, cs.FORCE_CLOSING),
(cs.CLOSING, cs.FORCE_CLOSING),
# we can get force closed almost any time
(cs.OPENING, cs.CLOSED),
(cs.FUNDED, cs.CLOSED),
(cs.OPEN, cs.CLOSED),
(cs.SHUTDOWN, cs.CLOSED),
(cs.CLOSING, cs.CLOSED),
#
(cs.FORCE_CLOSING, cs.FORCE_CLOSING), # allow multiple attempts
(cs.FORCE_CLOSING, cs.CLOSED),
(cs.FORCE_CLOSING, cs.REDEEMED),
(cs.CLOSED, cs.REDEEMED),
(cs.OPENING, cs.REDEEMED), # channel never funded (dropped from mempool)
(cs.PREOPENING, cs.REDEEMED), # channel never funded
]
del cs # delete as name is ambiguous without context
class RevokeAndAck(NamedTuple):
per_commitment_secret: bytes
next_per_commitment_point: bytes
class RemoteCtnTooFarInFuture(Exception): pass
def htlcsum(htlcs: Iterable[UpdateAddHtlc]):
return sum([x.amount_msat for x in htlcs])
class AbstractChannel(Logger, ABC):
storage: Union['StoredDict', dict]
config: Dict[HTLCOwner, Union[LocalConfig, RemoteConfig]]
_sweep_info: Dict[str, Dict[str, 'SweepInfo']]
lnworker: Optional['LNWallet']
_fallback_sweep_address: str
channel_id: bytes
funding_outpoint: Outpoint
node_id: bytes
_state: ChannelState
def set_short_channel_id(self, short_id: ShortChannelID) -> None:
self.short_channel_id = short_id
self.storage["short_channel_id"] = short_id
def get_id_for_log(self) -> str:
scid = self.short_channel_id
if scid:
return str(scid)
return self.channel_id.hex()
def short_id_for_GUI(self) -> str:
return format_short_channel_id(self.short_channel_id)
def set_state(self, state: ChannelState) -> None:
""" set on-chain state """
old_state = self._state
if (old_state, state) not in state_transitions:
raise Exception(f"Transition not allowed: {old_state.name} -> {state.name}")
self.logger.debug(f'Setting channel state: {old_state.name} -> {state.name}')
self._state = state
self.storage['state'] = self._state.name
if self.lnworker:
self.lnworker.channel_state_changed(self)
def get_state(self) -> ChannelState:
return self._state
def is_funded(self):
return self.get_state() >= ChannelState.FUNDED
def is_open(self):
return self.get_state() == ChannelState.OPEN
def is_closing(self):
return ChannelState.SHUTDOWN <= self.get_state() <= ChannelState.FORCE_CLOSING
def is_closed(self):
# the closing txid has been saved
return self.get_state() >= ChannelState.CLOSING
def is_redeemed(self):
return self.get_state() == ChannelState.REDEEMED
def save_funding_height(self, *, txid: str, height: int, timestamp: Optional[int]) -> None:
self.storage['funding_height'] = txid, height, timestamp
def get_funding_height(self):
return self.storage.get('funding_height')
def delete_funding_height(self):
self.storage.pop('funding_height', None)
def save_closing_height(self, *, txid: str, height: int, timestamp: Optional[int]) -> None:
self.storage['closing_height'] = txid, height, timestamp
def get_closing_height(self):
return self.storage.get('closing_height')
def delete_closing_height(self):
self.storage.pop('closing_height', None)
def create_sweeptxs_for_our_ctx(self, ctx):
return create_sweeptxs_for_our_ctx(chan=self, ctx=ctx, sweep_address=self.sweep_address)
def create_sweeptxs_for_their_ctx(self, ctx):
return create_sweeptxs_for_their_ctx(chan=self, ctx=ctx, sweep_address=self.sweep_address)
def is_backup(self):
return False
def sweep_ctx(self, ctx: Transaction) -> Dict[str, SweepInfo]:
txid = ctx.txid()
if self._sweep_info.get(txid) is None:
our_sweep_info = self.create_sweeptxs_for_our_ctx(ctx)
their_sweep_info = self.create_sweeptxs_for_their_ctx(ctx)
if our_sweep_info is not None:
self._sweep_info[txid] = our_sweep_info
self.logger.info(f'we force closed')
elif their_sweep_info is not None:
self._sweep_info[txid] = their_sweep_info
self.logger.info(f'they force closed.')
else:
self._sweep_info[txid] = {}
self.logger.info(f'not sure who closed.')
return self._sweep_info[txid]
def update_onchain_state(self, *, funding_txid: str, funding_height: TxMinedInfo,
closing_txid: str, closing_height: TxMinedInfo, keep_watching: bool) -> None:
# note: state transitions are irreversible, but
# save_funding_height, save_closing_height are reversible
if funding_height.height == TX_HEIGHT_LOCAL:
self.update_unfunded_state()
elif closing_height.height == TX_HEIGHT_LOCAL:
self.update_funded_state(funding_txid=funding_txid, funding_height=funding_height)
else:
self.update_closed_state(funding_txid=funding_txid,
funding_height=funding_height,
closing_txid=closing_txid,
closing_height=closing_height,
keep_watching=keep_watching)
def update_unfunded_state(self):
self.delete_funding_height()
self.delete_closing_height()
if self.get_state() in [ChannelState.PREOPENING, ChannelState.OPENING, ChannelState.FORCE_CLOSING] and self.lnworker:
if self.is_initiator():
# set channel state to REDEEMED so that it can be removed manually
# to protect ourselves against a server lying by omission,
# we check that funding_inputs have been double spent and deeply mined
inputs = self.storage.get('funding_inputs', [])
if not inputs:
self.logger.info(f'channel funding inputs are not provided')
self.set_state(ChannelState.REDEEMED)
for i in inputs:
spender_txid = self.lnworker.wallet.db.get_spent_outpoint(*i)
if spender_txid is None:
continue
if spender_txid != self.funding_outpoint.txid:
tx_mined_height = self.lnworker.wallet.get_tx_height(spender_txid)
if tx_mined_height.conf > lnutil.REDEEM_AFTER_DOUBLE_SPENT_DELAY:
self.logger.info(f'channel is double spent {inputs}')
self.set_state(ChannelState.REDEEMED)
break
else:
now = int(time.time())
if now - self.storage.get('init_timestamp', 0) > CHANNEL_OPENING_TIMEOUT:
self.lnworker.remove_channel(self.channel_id)
def update_funded_state(self, *, funding_txid: str, funding_height: TxMinedInfo) -> None:
self.save_funding_height(txid=funding_txid, height=funding_height.height, timestamp=funding_height.timestamp)
self.delete_closing_height()
if funding_height.conf>0:
self.set_short_channel_id(ShortChannelID.from_components(
funding_height.height, funding_height.txpos, self.funding_outpoint.output_index))
if self.get_state() == ChannelState.OPENING:
if self.is_funding_tx_mined(funding_height):
self.set_state(ChannelState.FUNDED)
def update_closed_state(self, *, funding_txid: str, funding_height: TxMinedInfo,
closing_txid: str, closing_height: TxMinedInfo, keep_watching: bool) -> None:
self.save_funding_height(txid=funding_txid, height=funding_height.height, timestamp=funding_height.timestamp)
self.save_closing_height(txid=closing_txid, height=closing_height.height, timestamp=closing_height.timestamp)
if funding_height.conf>0:
self.set_short_channel_id(ShortChannelID.from_components(
funding_height.height, funding_height.txpos, self.funding_outpoint.output_index))
if self.get_state() < ChannelState.CLOSED:
conf = closing_height.conf
if conf > 0:
self.set_state(ChannelState.CLOSED)
else:
# we must not trust the server with unconfirmed transactions
# if the remote force closed, we remain OPEN until the closing tx is confirmed
pass
if self.get_state() == ChannelState.CLOSED and not keep_watching:
self.set_state(ChannelState.REDEEMED)
@property
def sweep_address(self) -> str:
# TODO: in case of unilateral close with pending HTLCs, this address will be reused
addr = None
if self.is_static_remotekey_enabled():
our_payment_pubkey = self.config[LOCAL].payment_basepoint.pubkey
addr = make_commitment_output_to_remote_address(our_payment_pubkey)
if addr is None:
addr = self._fallback_sweep_address
assert addr
if self.lnworker:
assert self.lnworker.wallet.is_mine(addr)
return addr
@abstractmethod
def is_initiator(self) -> bool:
pass
@abstractmethod
def is_funding_tx_mined(self, funding_height: TxMinedInfo) -> bool:
pass
@abstractmethod
def get_funding_address(self) -> str:
pass
@abstractmethod
def get_state_for_GUI(self) -> str:
pass
@abstractmethod
def get_oldest_unrevoked_ctn(self, subject: HTLCOwner) -> int:
pass
@abstractmethod
def included_htlcs(self, subject: HTLCOwner, direction: Direction, ctn: int = None) -> Sequence[UpdateAddHtlc]:
pass
@abstractmethod
def funding_txn_minimum_depth(self) -> int:
pass
@abstractmethod
def balance(self, whose: HTLCOwner, *, ctx_owner=HTLCOwner.LOCAL, ctn: int = None) -> int:
"""This balance (in msat) only considers HTLCs that have been settled by ctn.
It disregards reserve, fees, and pending HTLCs (in both directions).
"""
pass
@abstractmethod
def balance_minus_outgoing_htlcs(self, whose: HTLCOwner, *,
ctx_owner: HTLCOwner = HTLCOwner.LOCAL,
ctn: int = None) -> int:
"""This balance (in msat), which includes the value of
pending outgoing HTLCs, is used in the UI.
"""
pass
@abstractmethod
def is_frozen_for_sending(self) -> bool:
"""Whether the user has marked this channel as frozen for sending.
Frozen channels are not supposed to be used for new outgoing payments.
(note that payment-forwarding ignores this option)
"""
pass
@abstractmethod
def is_frozen_for_receiving(self) -> bool:
"""Whether the user has marked this channel as frozen for receiving.
Frozen channels are not supposed to be used for new incoming payments.
(note that payment-forwarding ignores this option)
"""
pass
@abstractmethod
def is_static_remotekey_enabled(self) -> bool:
pass
class ChannelBackup(AbstractChannel):
"""
current capabilities:
- detect force close
- request force close
- sweep my ctx to_local
future:
- will need to sweep their ctx to_remote
"""
def __init__(self, cb: ChannelBackupStorage, *, sweep_address=None, lnworker=None):
self.name = None
Logger.__init__(self)
self.cb = cb
self._sweep_info = {}
self._fallback_sweep_address = sweep_address
self.storage = {} # dummy storage
self._state = ChannelState.OPENING
self.config = {}
self.config[LOCAL] = LocalConfig.from_seed(
channel_seed=cb.channel_seed,
to_self_delay=cb.local_delay,
# dummy values
static_remotekey=None,
dust_limit_sat=None,
max_htlc_value_in_flight_msat=None,
max_accepted_htlcs=None,
initial_msat=None,
reserve_sat=None,
funding_locked_received=False,
was_announced=False,
current_commitment_signature=None,
current_htlc_signatures=b'',
htlc_minimum_msat=1,
upfront_shutdown_script='')
self.config[REMOTE] = RemoteConfig(
payment_basepoint=OnlyPubkeyKeypair(cb.remote_payment_pubkey),
revocation_basepoint=OnlyPubkeyKeypair(cb.remote_revocation_pubkey),
to_self_delay=cb.remote_delay,
# dummy values
multisig_key=OnlyPubkeyKeypair(None),
htlc_basepoint=OnlyPubkeyKeypair(None),
delayed_basepoint=OnlyPubkeyKeypair(None),
dust_limit_sat=None,
max_htlc_value_in_flight_msat=None,
max_accepted_htlcs=None,
initial_msat = None,
reserve_sat = None,
htlc_minimum_msat=None,
next_per_commitment_point=None,
current_per_commitment_point=None,
upfront_shutdown_script='')
self.node_id = cb.node_id
self.channel_id = cb.channel_id()
self.funding_outpoint = cb.funding_outpoint()
self.lnworker = lnworker
self.short_channel_id = None
def is_backup(self):
return True
def create_sweeptxs_for_their_ctx(self, ctx):
return {}
def get_funding_address(self):
return self.cb.funding_address
def is_initiator(self):
return self.cb.is_initiator
def short_id_for_GUI(self) -> str:
if self.short_channel_id:
return 'BACKUP of ' + format_short_channel_id(self.short_channel_id)
else:
return 'BACKUP'
def get_state_for_GUI(self):
cs = self.get_state()
return cs.name
def get_oldest_unrevoked_ctn(self, who):
return -1
def included_htlcs(self, subject, direction, ctn=None):
return []
def funding_txn_minimum_depth(self):
return 1
def is_funding_tx_mined(self, funding_height):
return funding_height.conf > 1
def balance_minus_outgoing_htlcs(self, whose: HTLCOwner, *, ctx_owner: HTLCOwner = HTLCOwner.LOCAL, ctn: int = None):
return 0
def balance(self, whose: HTLCOwner, *, ctx_owner=HTLCOwner.LOCAL, ctn: int = None) -> int:
return 0
def is_frozen_for_sending(self) -> bool:
return False
def is_frozen_for_receiving(self) -> bool:
return False
def is_static_remotekey_enabled(self) -> bool:
# Return False so that self.sweep_address will return self._fallback_sweep_address
# Since channel backups do not save the static_remotekey, payment_basepoint in
# their local config is not static)
return False
class Channel(AbstractChannel):
# note: try to avoid naming ctns/ctxs/etc as "current" and "pending".
# they are ambiguous. Use "oldest_unrevoked" or "latest" or "next".
# TODO enforce this ^
def __init__(self, state: 'StoredDict', *, sweep_address=None, name=None, lnworker=None, initial_feerate=None):
self.name = name
Logger.__init__(self)
self.lnworker = lnworker
self._fallback_sweep_address = sweep_address
self.storage = state
self.db_lock = self.storage.db.lock if self.storage.db else threading.RLock()
self.config = {}
self.config[LOCAL] = state["local_config"]
self.config[REMOTE] = state["remote_config"]
self.channel_id = bfh(state["channel_id"])
self.constraints = state["constraints"] # type: ChannelConstraints
self.funding_outpoint = state["funding_outpoint"]
self.node_id = bfh(state["node_id"])
self.short_channel_id = ShortChannelID.normalize(state["short_channel_id"])
self.onion_keys = state['onion_keys'] # type: Dict[int, bytes]
self.data_loss_protect_remote_pcp = state['data_loss_protect_remote_pcp']
self.hm = HTLCManager(log=state['log'], initial_feerate=initial_feerate)
self._state = ChannelState[state['state']]
self.peer_state = PeerState.DISCONNECTED
self._sweep_info = {}
self._outgoing_channel_update = None # type: Optional[bytes]
self._chan_ann_without_sigs = None # type: Optional[bytes]
self.revocation_store = RevocationStore(state["revocation_store"])
self._can_send_ctx_updates = True # type: bool
self._receive_fail_reasons = {} # type: Dict[int, (bytes, OnionRoutingFailureMessage)]
self._ignore_max_htlc_value = False # used in tests
def is_initiator(self):
return self.constraints.is_initiator
def is_active(self):
return self.get_state() == ChannelState.OPEN and self.peer_state == PeerState.GOOD
def funding_txn_minimum_depth(self):
return self.constraints.funding_txn_minimum_depth
def diagnostic_name(self):
if self.name:
return str(self.name)
try:
return f"lnchannel_{bh2u(self.channel_id[-4:])}"
except:
return super().diagnostic_name()
def set_onion_key(self, key: int, value: bytes):
self.onion_keys[key] = value
def get_onion_key(self, key: int) -> bytes:
return self.onion_keys.get(key)
def set_data_loss_protect_remote_pcp(self, key, value):
self.data_loss_protect_remote_pcp[key] = value
def get_data_loss_protect_remote_pcp(self, key):
return self.data_loss_protect_remote_pcp.get(key)
def get_local_pubkey(self) -> bytes:
if not self.lnworker:
raise Exception('lnworker not set for channel!')
return self.lnworker.node_keypair.pubkey
def set_remote_update(self, raw: bytes) -> None:
self.storage['remote_update'] = raw.hex()
def get_remote_update(self) -> Optional[bytes]:
return bfh(self.storage.get('remote_update')) if self.storage.get('remote_update') else None
def add_or_update_peer_addr(self, peer: LNPeerAddr) -> None:
if 'peer_network_addresses' not in self.storage:
self.storage['peer_network_addresses'] = {}
now = int(time.time())
self.storage['peer_network_addresses'][peer.net_addr_str()] = now
def get_peer_addresses(self) -> Iterator[LNPeerAddr]:
# sort by timestamp: most recent first
addrs = sorted(self.storage.get('peer_network_addresses', {}).items(),
key=lambda x: x[1], reverse=True)
for net_addr_str, ts in addrs:
net_addr = NetAddress.from_string(net_addr_str)
yield LNPeerAddr(host=str(net_addr.host), port=net_addr.port, pubkey=self.node_id)
def get_outgoing_gossip_channel_update(self) -> bytes:
if self._outgoing_channel_update is not None:
return self._outgoing_channel_update
if not self.lnworker:
raise Exception('lnworker not set for channel!')
sorted_node_ids = list(sorted([self.node_id, self.get_local_pubkey()]))
channel_flags = b'\x00' if sorted_node_ids[0] == self.get_local_pubkey() else b'\x01'
now = int(time.time())
htlc_maximum_msat = min(self.config[REMOTE].max_htlc_value_in_flight_msat, 1000 * self.constraints.capacity)
chan_upd = encode_msg(
"channel_update",
short_channel_id=self.short_channel_id,
channel_flags=channel_flags,
message_flags=b'\x01',
cltv_expiry_delta=lnutil.NBLOCK_OUR_CLTV_EXPIRY_DELTA,
htlc_minimum_msat=self.config[REMOTE].htlc_minimum_msat,
htlc_maximum_msat=htlc_maximum_msat,
fee_base_msat=lnutil.OUR_FEE_BASE_MSAT,
fee_proportional_millionths=lnutil.OUR_FEE_PROPORTIONAL_MILLIONTHS,
chain_hash=constants.net.rev_genesis_bytes(),
timestamp=now,
)
sighash = sha256d(chan_upd[2 + 64:])
sig = ecc.ECPrivkey(self.lnworker.node_keypair.privkey).sign(sighash, ecc.sig_string_from_r_and_s)
message_type, payload = decode_msg(chan_upd)
payload['signature'] = sig
chan_upd = encode_msg(message_type, **payload)
self._outgoing_channel_update = chan_upd
return chan_upd
def construct_channel_announcement_without_sigs(self) -> bytes:
if self._chan_ann_without_sigs is not None:
return self._chan_ann_without_sigs
if not self.lnworker:
raise Exception('lnworker not set for channel!')
bitcoin_keys = [self.config[REMOTE].multisig_key.pubkey,
self.config[LOCAL].multisig_key.pubkey]
node_ids = [self.node_id, self.get_local_pubkey()]
sorted_node_ids = list(sorted(node_ids))
if sorted_node_ids != node_ids:
node_ids = sorted_node_ids
bitcoin_keys.reverse()
chan_ann = encode_msg(
"channel_announcement",
len=0,
features=b'',
chain_hash=constants.net.rev_genesis_bytes(),
short_channel_id=self.short_channel_id,
node_id_1=node_ids[0],
node_id_2=node_ids[1],
bitcoin_key_1=bitcoin_keys[0],
bitcoin_key_2=bitcoin_keys[1],
)
self._chan_ann_without_sigs = chan_ann
return chan_ann
def is_static_remotekey_enabled(self) -> bool:
return bool(self.storage.get('static_remotekey_enabled'))
def get_wallet_addresses_channel_might_want_reserved(self) -> Sequence[str]:
ret = []
if self.is_static_remotekey_enabled():
our_payment_pubkey = self.config[LOCAL].payment_basepoint.pubkey
to_remote_address = make_commitment_output_to_remote_address(our_payment_pubkey)
ret.append(to_remote_address)
return ret
def get_feerate(self, subject: HTLCOwner, *, ctn: int) -> int:
# returns feerate in sat/kw
return self.hm.get_feerate(subject, ctn)
def get_oldest_unrevoked_feerate(self, subject: HTLCOwner) -> int:
return self.hm.get_feerate_in_oldest_unrevoked_ctx(subject)
def get_latest_feerate(self, subject: HTLCOwner) -> int:
return self.hm.get_feerate_in_latest_ctx(subject)
def get_next_feerate(self, subject: HTLCOwner) -> int:
return self.hm.get_feerate_in_next_ctx(subject)
def get_payments(self):
out = []
for direction, htlc in self.hm.all_htlcs_ever():
htlc_proposer = LOCAL if direction is SENT else REMOTE
if self.hm.was_htlc_failed(htlc_id=htlc.htlc_id, htlc_proposer=htlc_proposer):
status = 'failed'
elif self.hm.was_htlc_preimage_released(htlc_id=htlc.htlc_id, htlc_proposer=htlc_proposer):
status = 'settled'
else:
status = 'inflight'
rhash = htlc.payment_hash.hex()
out.append((rhash, self.channel_id, htlc, direction, status))
return out
def get_settled_payments(self):
out = defaultdict(list)
for direction, htlc in self.hm.all_htlcs_ever():
htlc_proposer = LOCAL if direction is SENT else REMOTE
if self.hm.was_htlc_preimage_released(htlc_id=htlc.htlc_id, htlc_proposer=htlc_proposer):
rhash = htlc.payment_hash.hex()
out[rhash].append((self.channel_id, htlc, direction))
return out
def open_with_first_pcp(self, remote_pcp: bytes, remote_sig: bytes) -> None:
with self.db_lock:
self.config[REMOTE].current_per_commitment_point = remote_pcp
self.config[REMOTE].next_per_commitment_point = None
self.config[LOCAL].current_commitment_signature = remote_sig
self.hm.channel_open_finished()
self.peer_state = PeerState.GOOD
def get_state_for_GUI(self):
# status displayed in the GUI
cs = self.get_state()
if self.is_closed():
return cs.name
ps = self.peer_state
if ps != PeerState.GOOD:
return ps.name
return cs.name
def set_can_send_ctx_updates(self, b: bool) -> None:
self._can_send_ctx_updates = b
def can_send_ctx_updates(self) -> bool:
"""Whether we can send update_fee, update_*_htlc changes to the remote."""
if not (self.is_open() or self.is_closing()):
return False
if self.peer_state != PeerState.GOOD:
return False
if not self._can_send_ctx_updates:
return False
return True
def can_send_update_add_htlc(self) -> bool:
return self.can_send_ctx_updates() and not self.is_closing()
def is_frozen_for_sending(self) -> bool:
return self.storage.get('frozen_for_sending', False)
def set_frozen_for_sending(self, b: bool) -> None:
self.storage['frozen_for_sending'] = bool(b)
util.trigger_callback('channel', self.lnworker.wallet, self)
def is_frozen_for_receiving(self) -> bool:
return self.storage.get('frozen_for_receiving', False)
def set_frozen_for_receiving(self, b: bool) -> None:
self.storage['frozen_for_receiving'] = bool(b)
util.trigger_callback('channel', self.lnworker.wallet, self)
def _assert_can_add_htlc(self, *, htlc_proposer: HTLCOwner, amount_msat: int,
ignore_min_htlc_value: bool = False) -> None:
"""Raises PaymentFailure if the htlc_proposer cannot add this new HTLC.
(this is relevant both for forwarding and endpoint)
"""
htlc_receiver = htlc_proposer.inverted()
# note: all these tests are about the *receiver's* *next* commitment transaction,
# and the constraints are the ones imposed by their config
ctn = self.get_next_ctn(htlc_receiver)
chan_config = self.config[htlc_receiver]
if self.get_state() != ChannelState.OPEN:
raise PaymentFailure('Channel not open', self.get_state())
if htlc_proposer == LOCAL:
if not self.can_send_ctx_updates():
raise PaymentFailure('Channel cannot send ctx updates')
if not self.can_send_update_add_htlc():
raise PaymentFailure('Channel cannot add htlc')
# If proposer is LOCAL we apply stricter checks as that is behaviour we can control.
# This should lead to fewer disagreements (i.e. channels failing).
strict = (htlc_proposer == LOCAL)
# check htlc raw value
if not ignore_min_htlc_value:
if amount_msat <= 0:
raise PaymentFailure("HTLC value must be positive")
if amount_msat < chan_config.htlc_minimum_msat:
raise PaymentFailure(f'HTLC value too small: {amount_msat} msat')
if amount_msat > LN_MAX_HTLC_VALUE_MSAT and not self._ignore_max_htlc_value:
raise PaymentFailure(f"HTLC value over protocol maximum: {amount_msat} > {LN_MAX_HTLC_VALUE_MSAT} msat")
# check proposer can afford htlc
max_can_send_msat = self.available_to_spend(htlc_proposer, strict=strict)
if max_can_send_msat < amount_msat:
raise PaymentFailure(f'Not enough balance. can send: {max_can_send_msat}, tried: {amount_msat}')
# check "max_accepted_htlcs"
# this is the loose check BOLT-02 specifies:
if len(self.hm.htlcs_by_direction(htlc_receiver, direction=RECEIVED, ctn=ctn)) + 1 > chan_config.max_accepted_htlcs:
raise PaymentFailure('Too many HTLCs already in channel')
# however, c-lightning is a lot stricter, so extra checks:
if strict:
max_concurrent_htlcs = min(self.config[htlc_proposer].max_accepted_htlcs,
self.config[htlc_receiver].max_accepted_htlcs)
if len(self.hm.htlcs(htlc_receiver, ctn=ctn)) + 1 > max_concurrent_htlcs:
raise PaymentFailure('Too many HTLCs already in channel')
# check "max_htlc_value_in_flight_msat"
current_htlc_sum = htlcsum(self.hm.htlcs_by_direction(htlc_receiver, direction=RECEIVED, ctn=ctn).values())
if current_htlc_sum + amount_msat > chan_config.max_htlc_value_in_flight_msat:
raise PaymentFailure(f'HTLC value sum (sum of pending htlcs: {current_htlc_sum/1000} sat '
f'plus new htlc: {amount_msat/1000} sat) '
f'would exceed max allowed: {chan_config.max_htlc_value_in_flight_msat/1000} sat')
def can_pay(self, amount_msat: int, *, check_frozen=False) -> bool:
"""Returns whether we can add an HTLC of given value."""
if check_frozen and self.is_frozen_for_sending():
return False
try:
self._assert_can_add_htlc(htlc_proposer=LOCAL, amount_msat=amount_msat)
except PaymentFailure:
return False
return True
def can_receive(self, amount_msat: int, *, check_frozen=False,
ignore_min_htlc_value: bool = False) -> bool:
"""Returns whether the remote can add an HTLC of given value."""
if check_frozen and self.is_frozen_for_receiving():
return False
try:
self._assert_can_add_htlc(htlc_proposer=REMOTE,
amount_msat=amount_msat,
ignore_min_htlc_value=ignore_min_htlc_value)
except PaymentFailure:
return False
return True
def should_try_to_reestablish_peer(self) -> bool:
return ChannelState.PREOPENING < self._state < ChannelState.CLOSING and self.peer_state == PeerState.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: UpdateAddHtlc) -> UpdateAddHtlc:
"""Adds a new LOCAL HTLC to the channel.
Action must be initiated by LOCAL.
"""
if isinstance(htlc, dict): # legacy conversion # FIXME remove
htlc = UpdateAddHtlc(**htlc)
assert isinstance(htlc, UpdateAddHtlc)
self._assert_can_add_htlc(htlc_proposer=LOCAL, amount_msat=htlc.amount_msat)
if htlc.htlc_id is None:
htlc = attr.evolve(htlc, htlc_id=self.hm.get_next_htlc_id(LOCAL))
with self.db_lock:
self.hm.send_htlc(htlc)
self.logger.info("add_htlc")
return htlc
def receive_htlc(self, htlc: UpdateAddHtlc, onion_packet:bytes = None) -> UpdateAddHtlc:
"""Adds a new REMOTE HTLC to the channel.
Action must be initiated by REMOTE.
"""
if isinstance(htlc, dict): # legacy conversion # FIXME remove
htlc = UpdateAddHtlc(**htlc)
assert isinstance(htlc, UpdateAddHtlc)
try:
self._assert_can_add_htlc(htlc_proposer=REMOTE, amount_msat=htlc.amount_msat)
except PaymentFailure as e:
raise RemoteMisbehaving(e) from e
if htlc.htlc_id is None: # used in unit tests
htlc = attr.evolve(htlc, htlc_id=self.hm.get_next_htlc_id(REMOTE))
with self.db_lock:
self.hm.recv_htlc(htlc)
local_ctn = self.get_latest_ctn(LOCAL)
remote_ctn = self.get_latest_ctn(REMOTE)
if onion_packet:
self.hm.log['unfulfilled_htlcs'][htlc.htlc_id] = local_ctn, remote_ctn, onion_packet.hex(), False
self.logger.info("receive_htlc")
return htlc
def sign_next_commitment(self) -> Tuple[bytes, Sequence[bytes]]:
"""Returns signatures for our next remote commitment tx.
Action must be initiated by LOCAL.
Finally, the next remote ctx becomes the latest remote ctx.
"""
next_remote_ctn = self.get_next_ctn(REMOTE)
self.logger.info(f"sign_next_commitment {next_remote_ctn}")
pending_remote_commitment = self.get_next_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')
htlcsigs = []
htlc_to_ctx_output_idx_map = map_htlcs_to_ctx_output_idxs(chan=self,
ctx=pending_remote_commitment,
pcp=self.config[REMOTE].next_per_commitment_point,
subject=REMOTE,
ctn=next_remote_ctn)
for (direction, htlc), (ctx_output_idx, htlc_relative_idx) in htlc_to_ctx_output_idx_map.items():
_script, htlc_tx = make_htlc_tx_with_open_channel(chan=self,
pcp=self.config[REMOTE].next_per_commitment_point,
subject=REMOTE,
ctn=next_remote_ctn,
htlc_direction=direction,
commit=pending_remote_commitment,
ctx_output_idx=ctx_output_idx,
htlc=htlc)
sig = bfh(htlc_tx.sign_txin(0, their_remote_htlc_privkey))
htlc_sig = ecc.sig_string_from_der_sig(sig[:-1])
htlcsigs.append((ctx_output_idx, htlc_sig))
htlcsigs.sort()
htlcsigs = [x[1] for x in htlcsigs]
with self.db_lock:
self.hm.send_ctx()
return sig_64, htlcsigs
def receive_new_commitment(self, sig: bytes, htlc_sigs: Sequence[bytes]) -> None:
"""Processes signatures for our next local commitment tx, sent by the REMOTE.
Action must be initiated by REMOTE.
If all checks pass, the next local ctx becomes the latest local ctx.
"""
# TODO in many failure cases below, we should "fail" the channel (force-close)
next_local_ctn = self.get_next_ctn(LOCAL)
self.logger.info(f"receive_new_commitment. ctn={next_local_ctn}, len(htlc_sigs)={len(htlc_sigs)}")
assert len(htlc_sigs) == 0 or type(htlc_sigs[0]) is bytes
pending_local_commitment = self.get_next_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(f'failed verifying signature of our updated commitment transaction: {bh2u(sig)} preimage is {preimage_hex}')
htlc_sigs_string = b''.join(htlc_sigs)
_secret, pcp = self.get_secret_and_point(subject=LOCAL, ctn=next_local_ctn)
htlc_to_ctx_output_idx_map = map_htlcs_to_ctx_output_idxs(chan=self,
ctx=pending_local_commitment,
pcp=pcp,
subject=LOCAL,
ctn=next_local_ctn)
if len(htlc_to_ctx_output_idx_map) != len(htlc_sigs):
raise Exception(f'htlc sigs failure. recv {len(htlc_sigs)} sigs, expected {len(htlc_to_ctx_output_idx_map)}')
for (direction, htlc), (ctx_output_idx, htlc_relative_idx) in htlc_to_ctx_output_idx_map.items():
htlc_sig = htlc_sigs[htlc_relative_idx]
self._verify_htlc_sig(htlc=htlc,
htlc_sig=htlc_sig,
htlc_direction=direction,
pcp=pcp,
ctx=pending_local_commitment,
ctx_output_idx=ctx_output_idx,
ctn=next_local_ctn)
with self.db_lock:
self.hm.recv_ctx()
self.config[LOCAL].current_commitment_signature=sig
self.config[LOCAL].current_htlc_signatures=htlc_sigs_string
def _verify_htlc_sig(self, *, htlc: UpdateAddHtlc, htlc_sig: bytes, htlc_direction: Direction,
pcp: bytes, ctx: Transaction, ctx_output_idx: int, ctn: int) -> None:
_script, htlc_tx = make_htlc_tx_with_open_channel(chan=self,
pcp=pcp,
subject=LOCAL,
ctn=ctn,
htlc_direction=htlc_direction,
commit=ctx,
ctx_output_idx=ctx_output_idx,
htlc=htlc)
pre_hash = sha256d(bfh(htlc_tx.serialize_preimage(0)))
remote_htlc_pubkey = derive_pubkey(self.config[REMOTE].htlc_basepoint.pubkey, pcp)
if not ecc.verify_signature(remote_htlc_pubkey, htlc_sig, pre_hash):
raise Exception(f'failed verifying HTLC signatures: {htlc} {htlc_direction}')
def get_remote_htlc_sig_for_htlc(self, *, htlc_relative_idx: int) -> bytes:
data = self.config[LOCAL].current_htlc_signatures
htlc_sigs = list(chunks(data, 64))
htlc_sig = htlc_sigs[htlc_relative_idx]
remote_htlc_sig = ecc.der_sig_from_sig_string(htlc_sig) + b'\x01'
return remote_htlc_sig
def revoke_current_commitment(self):
self.logger.info("revoke_current_commitment")
new_ctn = self.get_latest_ctn(LOCAL)
new_ctx = self.get_latest_commitment(LOCAL)
if not self.signature_fits(new_ctx):
# this should never fail; as receive_new_commitment already did this test
raise Exception("refusing to revoke as remote sig does not fit")
with self.db_lock:
self.hm.send_rev()
if self.lnworker:
received = self.hm.received_in_ctn(new_ctn)
for htlc in received:
self.lnworker.payment_received(self, htlc.payment_hash)
last_secret, last_point = self.get_secret_and_point(LOCAL, new_ctn - 1)
next_secret, next_point = self.get_secret_and_point(LOCAL, new_ctn + 1)
return RevokeAndAck(last_secret, next_point)
def receive_revocation(self, revocation: RevokeAndAck):
self.logger.info("receive_revocation")
new_ctn = self.get_latest_ctn(REMOTE)
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:
raise Exception('revoked secret not for current point')
with self.db_lock:
self.revocation_store.add_next_entry(revocation.per_commitment_secret)
##### start applying fee/htlc changes
self.hm.recv_rev()
self.config[REMOTE].current_per_commitment_point=self.config[REMOTE].next_per_commitment_point
self.config[REMOTE].next_per_commitment_point=revocation.next_per_commitment_point
# lnworker callbacks
if self.lnworker:
sent = self.hm.sent_in_ctn(new_ctn)
for htlc in sent:
self.lnworker.payment_sent(self, htlc.payment_hash)
failed = self.hm.failed_in_ctn(new_ctn)
for htlc in failed:
try:
error_bytes, failure_message = self._receive_fail_reasons.pop(htlc.htlc_id)
except KeyError:
error_bytes, failure_message = None, None
# if we are forwarding, save error message to disk
if self.lnworker.get_payment_info(htlc.payment_hash) is None:
self.save_fail_htlc_reason(htlc.htlc_id, error_bytes, failure_message)
else:
self.lnworker.payment_failed(self, htlc.payment_hash, error_bytes, failure_message)
def save_fail_htlc_reason(
self,
htlc_id: int,
error_bytes: Optional[bytes],
failure_message: Optional['OnionRoutingFailureMessage'],
):
error_hex = error_bytes.hex() if error_bytes else None
failure_hex = failure_message.to_bytes().hex() if failure_message else None
self.hm.log['fail_htlc_reasons'][htlc_id] = (error_hex, failure_hex)
def pop_fail_htlc_reason(self, htlc_id):
error_hex, failure_hex = self.hm.log['fail_htlc_reasons'].pop(htlc_id, (None, None))
error_bytes = bytes.fromhex(error_hex) if error_hex else None
failure_message = OnionRoutingFailureMessage.from_bytes(bytes.fromhex(failure_hex)) if failure_hex else None
return error_bytes, failure_message
def extract_preimage_from_htlc_txin(self, txin: TxInput) -> None:
witness = txin.witness_elements()
if len(witness) == 5: # HTLC success tx
preimage = witness[3]
elif len(witness) == 3: # spending offered HTLC directly from ctx
preimage = witness[1]
else:
return
payment_hash = sha256(preimage)
for direction, htlc in itertools.chain(self.hm.get_htlcs_in_oldest_unrevoked_ctx(REMOTE),
self.hm.get_htlcs_in_latest_ctx(REMOTE)):
if htlc.payment_hash == payment_hash:
is_sent = direction == RECEIVED
break
else:
for direction, htlc in itertools.chain(self.hm.get_htlcs_in_oldest_unrevoked_ctx(LOCAL),
self.hm.get_htlcs_in_latest_ctx(LOCAL)):
if htlc.payment_hash == payment_hash:
is_sent = direction == SENT
break
else:
return
if self.lnworker.get_preimage(payment_hash) is None:
self.logger.info(f'found preimage for {payment_hash.hex()} in witness of length {len(witness)}')
self.lnworker.save_preimage(payment_hash, preimage)
info = self.lnworker.get_payment_info(payment_hash)
if info is not None and info.status != PR_PAID:
if is_sent:
self.lnworker.payment_sent(self, payment_hash)
else:
self.lnworker.payment_received(self, payment_hash)
def balance(self, whose: HTLCOwner, *, ctx_owner=HTLCOwner.LOCAL, ctn: int = None) -> int:
assert type(whose) is HTLCOwner
initial = self.config[whose].initial_msat
return self.hm.get_balance_msat(whose=whose,
ctx_owner=ctx_owner,
ctn=ctn,
initial_balance_msat=initial)
def balance_minus_outgoing_htlcs(self, whose: HTLCOwner, *, ctx_owner: HTLCOwner = HTLCOwner.LOCAL,
ctn: int = None) -> int:
assert type(whose) is HTLCOwner
if ctn is None:
ctn = self.get_next_ctn(ctx_owner)
committed_balance = self.balance(whose, ctx_owner=ctx_owner, ctn=ctn)
direction = RECEIVED if whose != ctx_owner else SENT
balance_in_htlcs = self.balance_tied_up_in_htlcs_by_direction(ctx_owner, ctn=ctn, direction=direction)
return committed_balance - balance_in_htlcs
def balance_tied_up_in_htlcs_by_direction(self, ctx_owner: HTLCOwner = LOCAL, *, ctn: int = None,
direction: Direction):
# in msat
if ctn is None:
ctn = self.get_next_ctn(ctx_owner)
return htlcsum(self.hm.htlcs_by_direction(ctx_owner, direction, ctn).values())
def available_to_spend(self, subject: HTLCOwner, *, strict: bool = True) -> int:
"""The usable balance of 'subject' in msat, after taking reserve and fees into
consideration. Note that fees (and hence the result) fluctuate even without user interaction.
"""
assert type(subject) is HTLCOwner
sender = subject
receiver = subject.inverted()
initiator = LOCAL if self.constraints.is_initiator else REMOTE # the initiator/funder pays on-chain fees
is_frozen = self.is_frozen_for_sending() if subject == LOCAL else self.is_frozen_for_receiving()
if not self.is_active() or is_frozen:
return 0
def consider_ctx(*, ctx_owner: HTLCOwner, is_htlc_dust: bool) -> int:
ctn = self.get_next_ctn(ctx_owner)
sender_balance_msat = self.balance_minus_outgoing_htlcs(whose=sender, ctx_owner=ctx_owner, ctn=ctn)
receiver_balance_msat = self.balance_minus_outgoing_htlcs(whose=receiver, ctx_owner=ctx_owner, ctn=ctn)
sender_reserve_msat = self.config[receiver].reserve_sat * 1000
receiver_reserve_msat = self.config[sender].reserve_sat * 1000
num_htlcs_in_ctx = len(self.included_htlcs(ctx_owner, SENT, ctn=ctn) + self.included_htlcs(ctx_owner, RECEIVED, ctn=ctn))
feerate = self.get_feerate(ctx_owner, ctn=ctn)
ctx_fees_msat = calc_fees_for_commitment_tx(
num_htlcs=num_htlcs_in_ctx,
feerate=feerate,
is_local_initiator=self.constraints.is_initiator,
round_to_sat=False,
)
htlc_fee_msat = fee_for_htlc_output(feerate=feerate)
htlc_trim_func = received_htlc_trim_threshold_sat if ctx_owner == receiver else offered_htlc_trim_threshold_sat
htlc_trim_threshold_msat = htlc_trim_func(dust_limit_sat=self.config[ctx_owner].dust_limit_sat, feerate=feerate) * 1000
if sender == initiator == LOCAL: # see https://github.com/lightningnetwork/lightning-rfc/pull/740
fee_spike_buffer = calc_fees_for_commitment_tx(
num_htlcs=num_htlcs_in_ctx + int(not is_htlc_dust) + 1,
feerate=2 * feerate,
is_local_initiator=self.constraints.is_initiator,
round_to_sat=False,
)[sender]
max_send_msat = sender_balance_msat - sender_reserve_msat - fee_spike_buffer
else:
max_send_msat = sender_balance_msat - sender_reserve_msat - ctx_fees_msat[sender]
if is_htlc_dust:
return min(max_send_msat, htlc_trim_threshold_msat - 1)
else:
if sender == initiator:
return max_send_msat - htlc_fee_msat
else:
# the receiver is the initiator, so they need to be able to pay tx fees
if receiver_balance_msat - receiver_reserve_msat - ctx_fees_msat[receiver] - htlc_fee_msat < 0:
return 0
return max_send_msat
max_send_msat = min(
max(
consider_ctx(ctx_owner=receiver, is_htlc_dust=True),
consider_ctx(ctx_owner=receiver, is_htlc_dust=False),
),
max(
consider_ctx(ctx_owner=sender, is_htlc_dust=True),
consider_ctx(ctx_owner=sender, is_htlc_dust=False),
),
)
max_send_msat = max(max_send_msat, 0)
return max_send_msat
def included_htlcs(self, subject: HTLCOwner, direction: Direction, ctn: int = None, *,
feerate: int = None) -> Sequence[UpdateAddHtlc]:
"""Returns list of non-dust HTLCs for subject's commitment tx at ctn,
filtered by direction (of HTLCs).
"""
assert type(subject) is HTLCOwner
assert type(direction) is Direction
if ctn is None:
ctn = self.get_oldest_unrevoked_ctn(subject)
if feerate is None:
feerate = self.get_feerate(subject, ctn=ctn)
conf = self.config[subject]
if direction == RECEIVED:
threshold_sat = received_htlc_trim_threshold_sat(dust_limit_sat=conf.dust_limit_sat, feerate=feerate)
else:
threshold_sat = offered_htlc_trim_threshold_sat(dust_limit_sat=conf.dust_limit_sat, feerate=feerate)
htlcs = self.hm.htlcs_by_direction(subject, direction, ctn=ctn).values()
return list(filter(lambda htlc: htlc.amount_msat // 1000 >= threshold_sat, htlcs))
def get_secret_and_point(self, subject: HTLCOwner, ctn: int) -> Tuple[Optional[bytes], bytes]:
assert type(subject) is HTLCOwner
assert ctn >= 0, ctn
offset = ctn - self.get_oldest_unrevoked_ctn(subject)
if subject == REMOTE:
if offset > 1:
raise RemoteCtnTooFarInFuture(f"offset: {offset}")
conf = self.config[REMOTE]
if offset == 1:
secret = None
point = conf.next_per_commitment_point
elif offset == 0:
secret = None
point = conf.current_per_commitment_point
else:
secret = self.revocation_store.retrieve_secret(RevocationStore.START_INDEX - ctn)
point = secret_to_pubkey(int.from_bytes(secret, 'big'))
else:
secret = get_per_commitment_secret_from_seed(self.config[LOCAL].per_commitment_secret_seed, RevocationStore.START_INDEX - ctn)
point = secret_to_pubkey(int.from_bytes(secret, 'big'))
return secret, point
def get_secret_and_commitment(self, subject: HTLCOwner, *, ctn: int) -> Tuple[Optional[bytes], PartialTransaction]:
secret, point = self.get_secret_and_point(subject, ctn)
ctx = self.make_commitment(subject, point, ctn)
return secret, ctx
def get_commitment(self, subject: HTLCOwner, *, ctn: int) -> PartialTransaction:
secret, ctx = self.get_secret_and_commitment(subject, ctn=ctn)
return ctx
def get_next_commitment(self, subject: HTLCOwner) -> PartialTransaction:
ctn = self.get_next_ctn(subject)
return self.get_commitment(subject, ctn=ctn)
def get_latest_commitment(self, subject: HTLCOwner) -> PartialTransaction:
ctn = self.get_latest_ctn(subject)
return self.get_commitment(subject, ctn=ctn)
def get_oldest_unrevoked_commitment(self, subject: HTLCOwner) -> PartialTransaction:
ctn = self.get_oldest_unrevoked_ctn(subject)
return self.get_commitment(subject, ctn=ctn)
def create_sweeptxs(self, ctn: int) -> List[Transaction]:
from .lnsweep import create_sweeptxs_for_watchtower
secret, ctx = self.get_secret_and_commitment(REMOTE, ctn=ctn)
return create_sweeptxs_for_watchtower(self, ctx, secret, self.sweep_address)
def get_oldest_unrevoked_ctn(self, subject: HTLCOwner) -> int:
return self.hm.ctn_oldest_unrevoked(subject)
def get_latest_ctn(self, subject: HTLCOwner) -> int:
return self.hm.ctn_latest(subject)
def get_next_ctn(self, subject: HTLCOwner) -> int:
return self.hm.ctn_latest(subject) + 1
def total_msat(self, direction: Direction) -> int:
"""Return the cumulative total msat amount received/sent so far."""
assert type(direction) is Direction
return htlcsum(self.hm.all_settled_htlcs_ever_by_direction(LOCAL, direction))
def settle_htlc(self, preimage: bytes, htlc_id: int) -> None:
"""Settle/fulfill a pending received HTLC.
Action must be initiated by LOCAL.
"""
self.logger.info("settle_htlc")
assert self.can_send_ctx_updates(), f"cannot update channel. {self.get_state()!r} {self.peer_state!r}"
htlc = self.hm.get_htlc_by_id(REMOTE, htlc_id)
assert htlc.payment_hash == sha256(preimage)
assert htlc_id not in self.hm.log[REMOTE]['settles']
self.hm.send_settle(htlc_id)
def get_payment_hash(self, htlc_id: int) -> bytes:
htlc = self.hm.get_htlc_by_id(LOCAL, htlc_id)
return htlc.payment_hash
def decode_onion_error(self, reason: bytes, route: Sequence['RouteEdge'],
htlc_id: int) -> Tuple[OnionRoutingFailureMessage, int]:
failure_msg, sender_idx = decode_onion_error(
reason,
[x.node_id for x in route],
self.onion_keys[htlc_id])
return failure_msg, sender_idx
def receive_htlc_settle(self, preimage: bytes, htlc_id: int) -> None:
"""Settle/fulfill a pending offered HTLC.
Action must be initiated by REMOTE.
"""
self.logger.info("receive_htlc_settle")
htlc = self.hm.get_htlc_by_id(LOCAL, htlc_id)
assert htlc.payment_hash == sha256(preimage)
assert htlc_id not in self.hm.log[LOCAL]['settles']
with self.db_lock:
self.hm.recv_settle(htlc_id)
def fail_htlc(self, htlc_id: int) -> None:
"""Fail a pending received HTLC.
Action must be initiated by LOCAL.
"""
self.logger.info("fail_htlc")
assert self.can_send_ctx_updates(), f"cannot update channel. {self.get_state()!r} {self.peer_state!r}"
with self.db_lock:
self.hm.send_fail(htlc_id)
def receive_fail_htlc(self, htlc_id: int, *,
error_bytes: Optional[bytes],
reason: Optional[OnionRoutingFailureMessage] = None) -> None:
"""Fail a pending offered HTLC.
Action must be initiated by REMOTE.
"""
self.logger.info("receive_fail_htlc")
with self.db_lock:
self.hm.recv_fail(htlc_id)
self._receive_fail_reasons[htlc_id] = (error_bytes, reason)
def get_next_fee(self, subject: HTLCOwner) -> int:
return self.constraints.capacity - sum(x.value for x in self.get_next_commitment(subject).outputs())
def get_latest_fee(self, subject: HTLCOwner) -> int:
return self.constraints.capacity - sum(x.value for x in self.get_latest_commitment(subject).outputs())
def update_fee(self, feerate: int, from_us: bool) -> None:
# feerate uses sat/kw
if self.constraints.is_initiator != from_us:
raise Exception(f"Cannot update_fee: wrong initiator. us: {from_us}")
sender = LOCAL if from_us else REMOTE
ctx_owner = -sender
ctn = self.get_next_ctn(ctx_owner)
sender_balance_msat = self.balance_minus_outgoing_htlcs(whose=sender, ctx_owner=ctx_owner, ctn=ctn)
sender_reserve_msat = self.config[-sender].reserve_sat * 1000
num_htlcs_in_ctx = len(self.included_htlcs(ctx_owner, SENT, ctn=ctn, feerate=feerate) +
self.included_htlcs(ctx_owner, RECEIVED, ctn=ctn, feerate=feerate))
ctx_fees_msat = calc_fees_for_commitment_tx(
num_htlcs=num_htlcs_in_ctx,
feerate=feerate,
is_local_initiator=self.constraints.is_initiator,
)
remainder = sender_balance_msat - sender_reserve_msat - ctx_fees_msat[sender]
if remainder < 0:
raise Exception(f"Cannot update_fee. {sender} tried to update fee but they cannot afford it. "
f"Their balance would go below reserve: {remainder} msat missing.")
with self.db_lock:
if from_us:
assert self.can_send_ctx_updates(), f"cannot update channel. {self.get_state()!r} {self.peer_state!r}"
self.hm.send_update_fee(feerate)
else:
self.hm.recv_update_fee(feerate)
def make_commitment(self, subject: HTLCOwner, this_point: bytes, ctn: int) -> PartialTransaction:
assert type(subject) is HTLCOwner
feerate = self.get_feerate(subject, ctn=ctn)
other = subject.inverted()
local_msat = self.balance(subject, ctx_owner=subject, ctn=ctn)
remote_msat = self.balance(other, ctx_owner=subject, ctn=ctn)
received_htlcs = self.hm.htlcs_by_direction(subject, RECEIVED, ctn).values()
sent_htlcs = self.hm.htlcs_by_direction(subject, SENT, ctn).values()
remote_msat -= htlcsum(received_htlcs)
local_msat -= htlcsum(sent_htlcs)
assert remote_msat >= 0
assert local_msat >= 0
# same htlcs as before, but now without dust.
received_htlcs = self.included_htlcs(subject, RECEIVED, ctn)
sent_htlcs = self.included_htlcs(subject, SENT, ctn)
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]
for is_received_htlc, htlc_list in zip((True, False), (received_htlcs, sent_htlcs)):
for htlc in htlc_list:
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))
# note: maybe flip initiator here for fee purposes, we want LOCAL and REMOTE
# in the resulting dict to correspond to the to_local and to_remote *outputs* of the ctx
onchain_fees = calc_fees_for_commitment_tx(
num_htlcs=len(htlcs),
feerate=feerate,
is_local_initiator=self.constraints.is_initiator == (subject == LOCAL),
)
if self.is_static_remotekey_enabled():
payment_pubkey = other_config.payment_basepoint.pubkey
else:
payment_pubkey = derive_pubkey(other_config.payment_basepoint.pubkey, this_point)
return make_commitment(
ctn=ctn,
local_funding_pubkey=this_config.multisig_key.pubkey,
remote_funding_pubkey=other_config.multisig_key.pubkey,
remote_payment_pubkey=payment_pubkey,
funder_payment_basepoint=self.config[LOCAL if self.constraints.is_initiator else REMOTE].payment_basepoint.pubkey,
fundee_payment_basepoint=self.config[LOCAL if not self.constraints.is_initiator else REMOTE].payment_basepoint.pubkey,
revocation_pubkey=other_revocation_pubkey,
delayed_pubkey=derive_pubkey(this_config.delayed_basepoint.pubkey, this_point),
to_self_delay=other_config.to_self_delay,
funding_txid=self.funding_outpoint.txid,
funding_pos=self.funding_outpoint.output_index,
funding_sat=self.constraints.capacity,
local_amount=local_msat,
remote_amount=remote_msat,
dust_limit_sat=this_config.dust_limit_sat,
fees_per_participant=onchain_fees,
htlcs=htlcs,
)
def make_closing_tx(self, local_script: bytes, remote_script: bytes,
fee_sat: int, *, drop_remote = False) -> Tuple[bytes, PartialTransaction]:
""" cooperative close """
_, outputs = make_commitment_outputs(
fees_per_participant={
LOCAL: fee_sat * 1000 if self.constraints.is_initiator else 0,
REMOTE: fee_sat * 1000 if not self.constraints.is_initiator else 0,
},
local_amount_msat=self.balance(LOCAL),
remote_amount_msat=self.balance(REMOTE) if not drop_remote else 0,
local_script=bh2u(local_script),
remote_script=bh2u(remote_script),
htlcs=[],
dust_limit_sat=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 signature_fits(self, tx: PartialTransaction) -> bool:
remote_sig = self.config[LOCAL].current_commitment_signature
preimage_hex = tx.serialize_preimage(0)
msg_hash = sha256d(bfh(preimage_hex))
assert remote_sig
res = ecc.verify_signature(self.config[REMOTE].multisig_key.pubkey, remote_sig, msg_hash)
return res
def force_close_tx(self) -> PartialTransaction:
tx = self.get_latest_commitment(LOCAL)
assert self.signature_fits(tx)
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"
tx.add_signature_to_txin(txin_idx=0,
signing_pubkey=self.config[REMOTE].multisig_key.pubkey.hex(),
sig=remote_sig.hex())
assert tx.is_complete()
return tx
def maybe_sweep_revoked_htlc(self, ctx: Transaction, htlc_tx: Transaction) -> Optional[SweepInfo]:
# look at the output address, check if it matches
return create_sweeptx_for_their_revoked_htlc(self, ctx, htlc_tx, self.sweep_address)
def has_pending_changes(self, subject: HTLCOwner) -> bool:
next_htlcs = self.hm.get_htlcs_in_next_ctx(subject)
latest_htlcs = self.hm.get_htlcs_in_latest_ctx(subject)
return not (next_htlcs == latest_htlcs and self.get_next_feerate(subject) == self.get_latest_feerate(subject))
def should_be_closed_due_to_expiring_htlcs(self, local_height) -> bool:
htlcs_we_could_reclaim = {} # type: Dict[Tuple[Direction, int], UpdateAddHtlc]
# If there is a received HTLC for which we already released the preimage
# but the remote did not revoke yet, and the CLTV of this HTLC is dangerously close
# to the present, then unilaterally close channel
recv_htlc_deadline = lnutil.NBLOCK_DEADLINE_BEFORE_EXPIRY_FOR_RECEIVED_HTLCS
for sub, dir, ctn in ((LOCAL, RECEIVED, self.get_latest_ctn(LOCAL)),
(REMOTE, SENT, self.get_oldest_unrevoked_ctn(LOCAL)),
(REMOTE, SENT, self.get_latest_ctn(LOCAL)),):
for htlc_id, htlc in self.hm.htlcs_by_direction(subject=sub, direction=dir, ctn=ctn).items():
if not self.hm.was_htlc_preimage_released(htlc_id=htlc_id, htlc_proposer=REMOTE):
continue
if htlc.cltv_expiry - recv_htlc_deadline > local_height:
continue
htlcs_we_could_reclaim[(RECEIVED, htlc_id)] = htlc
# If there is an offered HTLC which has already expired (+ some grace period after), we
# will unilaterally close the channel and time out the HTLC
offered_htlc_deadline = lnutil.NBLOCK_DEADLINE_AFTER_EXPIRY_FOR_OFFERED_HTLCS
for sub, dir, ctn in ((LOCAL, SENT, self.get_latest_ctn(LOCAL)),
(REMOTE, RECEIVED, self.get_oldest_unrevoked_ctn(LOCAL)),
(REMOTE, RECEIVED, self.get_latest_ctn(LOCAL)),):
for htlc_id, htlc in self.hm.htlcs_by_direction(subject=sub, direction=dir, ctn=ctn).items():
if htlc.cltv_expiry + offered_htlc_deadline > local_height:
continue
htlcs_we_could_reclaim[(SENT, htlc_id)] = htlc
total_value_sat = sum([htlc.amount_msat // 1000 for htlc in htlcs_we_could_reclaim.values()])
num_htlcs = len(htlcs_we_could_reclaim)
min_value_worth_closing_channel_over_sat = max(num_htlcs * 10 * self.config[REMOTE].dust_limit_sat,
500_000)
return total_value_sat > min_value_worth_closing_channel_over_sat
def is_funding_tx_mined(self, funding_height):
funding_txid = self.funding_outpoint.txid
funding_idx = self.funding_outpoint.output_index
conf = funding_height.conf
if conf < self.funding_txn_minimum_depth():
self.logger.info(f"funding tx is still not at sufficient depth. actual depth: {conf}")
return False
assert conf > 0
# check funding_tx amount and script
funding_tx = self.lnworker.lnwatcher.db.get_transaction(funding_txid)
if not funding_tx:
self.logger.info(f"no funding_tx {funding_txid}")
return False
outp = funding_tx.outputs()[funding_idx]
redeem_script = funding_output_script(self.config[REMOTE], self.config[LOCAL])
funding_address = redeem_script_to_address('p2wsh', redeem_script)
funding_sat = self.constraints.capacity
if not (outp.address == funding_address and outp.value == funding_sat):
self.logger.info('funding outpoint mismatch')
return False
return True