# 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 dataclasses import enum from collections import defaultdict from enum import IntEnum, Enum from typing import ( Optional, Dict, List, Tuple, NamedTuple, Iterable, Sequence, TYPE_CHECKING, Iterator, Union, Mapping) import time import threading from abc import ABC, abstractmethod import itertools from aiorpcx import NetAddress import attr import electrum_ecc as ecc from electrum_ecc import ECPubkey from . import constants, util from .util import bfh, chunks, TxMinedInfo, error_text_bytes_to_safe_str from .bitcoin import redeem_script_to_address from .crypto import sha256, sha256d from .transaction import Transaction, PartialTransaction, TxInput, Sighash from .logging import Logger from .lntransport import LNPeerAddr from .lnonion import OnionRoutingFailure 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, 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, fee_for_htlc_output, offered_htlc_trim_threshold_sat, received_htlc_trim_threshold_sat, make_commitment_output_to_remote_address, FIXED_ANCHOR_SAT, ChannelType, LNProtocolWarning, ZEROCONF_TIMEOUT) from .lnsweep import sweep_our_ctx, sweep_their_ctx from .lnsweep import sweep_their_htlctx_justice, sweep_our_htlctx, SweepInfo from .lnsweep import sweep_their_ctx_to_remote_backup 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, ImportedChannelBackupStorage, OnchainChannelBackupStorage from .lnutil import format_short_channel_id from .fee_policy import FEERATE_PER_KW_MIN_RELAY_LIGHTNING if TYPE_CHECKING: from .lnworker import LNWallet from .json_db import StoredDict # channel flags CF_ANNOUNCE_CHANNEL = 0x01 # 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. REQUESTED_FCLOSE = 7 # Chan is open, but we have tried to request the *remote* to force-close WE_ARE_TOXIC = 8 # Chan is open, but we have lost state and the remote proved this. # The remote must force-close, it is *not* safe for us to do so. CLOSED = 9 # closing tx has been mined REDEEMED = 10 # 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), (cs.REQUESTED_FCLOSE, cs.FORCE_CLOSING), # we can request a force-close almost any time (cs.OPENING, cs.REQUESTED_FCLOSE), (cs.FUNDED, cs.REQUESTED_FCLOSE), (cs.OPEN, cs.REQUESTED_FCLOSE), (cs.SHUTDOWN, cs.REQUESTED_FCLOSE), (cs.CLOSING, cs.REQUESTED_FCLOSE), (cs.REQUESTED_FCLOSE, cs.REQUESTED_FCLOSE), # 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.REQUESTED_FCLOSE, cs.CLOSED), (cs.WE_ARE_TOXIC, cs.CLOSED), # during channel_reestablish, we might realise we have lost state (cs.OPENING, cs.WE_ARE_TOXIC), (cs.FUNDED, cs.WE_ARE_TOXIC), (cs.OPEN, cs.WE_ARE_TOXIC), (cs.SHUTDOWN, cs.WE_ARE_TOXIC), (cs.REQUESTED_FCLOSE, cs.WE_ARE_TOXIC), (cs.WE_ARE_TOXIC, cs.WE_ARE_TOXIC), # (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 ChanCloseOption(Enum): COOP_CLOSE = enum.auto() LOCAL_FCLOSE = enum.auto() REQUEST_REMOTE_FCLOSE = enum.auto() 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]) def now(): return int(time.time()) class HTLCWithStatus(NamedTuple): channel_id: bytes htlc: UpdateAddHtlc direction: Direction status: str class AbstractChannel(Logger, ABC): storage: Union['StoredDict', dict] config: Dict[HTLCOwner, Union[LocalConfig, RemoteConfig]] lnworker: Optional['LNWallet'] channel_id: bytes short_channel_id: Optional[ShortChannelID] = None funding_outpoint: Outpoint node_id: bytes # note that it might not be the full 33 bytes; for OCB it is only the prefix should_request_force_close: bool = False _state: ChannelState _who_closed: Optional[int] = None # HTLCOwner (1 or -1). 0 means "unknown" 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 diagnostic_name(self): return self.get_id_for_log() def set_state(self, state: ChannelState, *, force: bool = False) -> None: """Set on-chain state. `force` can be set while debugging from the console to allow illegal transitions. """ old_state = self._state if not force and (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) -> bool: return self.get_state() >= ChannelState.FUNDED def is_open(self) -> bool: return self.get_state() == ChannelState.OPEN def is_closed(self) -> bool: # the closing txid has been saved return self.get_state() >= ChannelState.CLOSING def is_closed_or_closing(self): # related: self.get_state_for_GUI return self.is_closed() or self.unconfirmed_closing_txid is not None def is_redeemed(self) -> bool: return self.get_state() == ChannelState.REDEEMED def need_to_subscribe(self) -> bool: """Whether lnwatcher/synchronizer need to be watching this channel.""" if not self.is_redeemed(): return True # Chan already deeply closed. Still, if some txs are missing, we should sub. # check we have funding tx # note: tx might not be directly related to the wallet, e.g. chan opened by remote if (funding_item := self.get_funding_height()) is None: return True if self.lnworker: funding_txid, funding_height, funding_timestamp = funding_item if self.lnworker.wallet.adb.get_transaction(funding_txid) is None: return True # check we have closing tx # note: tx might not be directly related to the wallet, e.g. local-fclose if (closing_item := self.get_closing_height()) is None: return True if self.lnworker: closing_txid, closing_height, closing_timestamp = closing_item if self.lnworker.wallet.adb.get_transaction(closing_txid) is None: return True return False @abstractmethod def get_close_options(self) -> Sequence[ChanCloseOption]: pass 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) -> Optional[Tuple[str, int, Optional[int]]]: 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) -> Optional[Tuple[str, int, Optional[int]]]: 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: Transaction) -> Dict[str, SweepInfo]: return sweep_our_ctx(chan=self, ctx=ctx) def create_sweeptxs_for_their_ctx(self, ctx: Transaction) -> Dict[str, SweepInfo]: return sweep_their_ctx(chan=self, ctx=ctx) def is_backup(self) -> bool: return False def get_local_scid_alias(self, *, create_new_if_needed: bool = False) -> Optional[bytes]: return None def get_remote_scid_alias(self) -> Optional[bytes]: return None def get_remote_peer_sent_error(self) -> Optional[str]: return None def get_ctx_sweep_info(self, ctx: Transaction) -> Tuple[bool, Dict[str, SweepInfo]]: our_sweep_info = self.create_sweeptxs_for_our_ctx(ctx) their_sweep_info = self.create_sweeptxs_for_their_ctx(ctx) if our_sweep_info: sweep_info = our_sweep_info who_closed = LOCAL elif their_sweep_info: sweep_info = their_sweep_info who_closed = REMOTE else: sweep_info = {} who_closed = 0 if self._who_closed != who_closed: # mostly here to limit log spam self._who_closed = who_closed if who_closed == LOCAL: self.logger.info(f'we (local) force closed') elif who_closed == REMOTE: self.logger.info(f'they (remote) force closed.') else: self.logger.info(f'not sure who closed. maybe co-op close?') is_local_ctx = who_closed == LOCAL return is_local_ctx, sweep_info def maybe_sweep_htlcs(self, ctx: Transaction, htlc_tx: Transaction) -> Dict[str, SweepInfo]: return {} def extract_preimage_from_htlc_txin(self, txin: TxInput, *, is_deeply_mined: bool) -> None: return 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) -> None: self.delete_funding_height() self.delete_closing_height() if not self.lnworker: return chan_age = now() - self.storage.get('init_timestamp', 0) state = self.get_state() if state in [ChannelState.PREOPENING, ChannelState.OPENING, ChannelState.FORCE_CLOSING]: 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.adb.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: if chan_age > CHANNEL_OPENING_TIMEOUT: self.lnworker.remove_channel(self.channel_id) elif self.is_zeroconf() and state in [ChannelState.OPEN, ChannelState.CLOSING, ChannelState.FORCE_CLOSING]: assert self.storage.get('init_timestamp') is not None, "init_timestamp not set for zeroconf channel" # handling zeroconf channels with no funding tx, can happen if broadcasting fails on LSP side # or if the LSP did double spent the funding tx/never published it intentionally # only remove a timed out OPEN channel if we are connected to the network to prevent removing it if we went # offline before seeing the funding tx if state != ChannelState.OPEN or chan_age > ZEROCONF_TIMEOUT and self.lnworker.network.is_connected(): # we delete the channel if its in closing state (either initiated manually by client or by LSP on failure) # or if the channel is not seeing any funding tx after 10 minutes to prevent further usage (limit damage) self.set_state(ChannelState.REDEEMED, force=True) local_balance_sat = int(self.balance(LOCAL) // 1000) if local_balance_sat > 0: self.logger.warning( f"we may have been scammed out of {local_balance_sat} sat by our " f"JIT provider: {self.lnworker.config.ZEROCONF_TRUSTED_NODE} or he didn't use our preimage") self.lnworker.config.ZEROCONF_TRUSTED_NODE = '' self.lnworker.lnwatcher.unwatch_channel(self.get_funding_address(), self.funding_outpoint.to_str()) # remove remaining local transactions from the wallet, this will also remove child transactions (closing tx) self.lnworker.lnwatcher.adb.remove_transaction(self.funding_outpoint.txid) 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) elif self.is_zeroconf() and funding_height.conf >= 3 and not self.should_request_force_close: if not self.is_funding_tx_mined(funding_height): # funding tx is invalid (invalid amount or address) we need to get rid of the channel again self.should_request_force_close = True if self.lnworker and self.node_id in self.lnworker.peers: # reconnect to trigger force close request self.lnworker.peers[self.node_id].close_and_cleanup() else: # remove zeroconf flag as we are now confirmed, this is to prevent an electrum server causing # us to remove a channel later in update_unfunded_state by omitting its funding tx self.remove_zeroconf_flag() 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) if self.lnworker: self.lnworker.wallet.txbatcher.set_password_future(None) else: # we must not trust the server with unconfirmed transactions, # because the state transition is irreversible. if the remote # force closed, we remain OPEN until the closing tx is confirmed self.unconfirmed_closing_txid = closing_txid if self.lnworker: util.trigger_callback('channel', self.lnworker.wallet, self) if self.get_state() == ChannelState.CLOSED and not keep_watching: self.set_state(ChannelState.REDEEMED) if self.lnworker and self.is_backup(): # auto-remove redeemed backups self.lnworker.remove_channel_backup(self.channel_id) @abstractmethod def is_initiator(self) -> bool: pass @abstractmethod def is_public(self) -> bool: pass @abstractmethod def is_zeroconf(self) -> bool: pass @abstractmethod def remove_zeroconf_flag(self) -> None: pass @abstractmethod def is_funding_tx_mined(self, funding_height: TxMinedInfo) -> bool: pass @abstractmethod def get_funding_address(self) -> str: pass def get_funding_tx(self) -> Optional[Transaction]: funding_txid = self.funding_outpoint.txid return self.lnworker.lnwatcher.adb.get_transaction(funding_txid) @abstractmethod def get_sweep_address(self) -> str: """Returns a wallet address we can use to sweep coins to. It could be something static to the channel (fixed for its lifecycle), or it might just ask the wallet now for an unused address. """ pass def get_state_for_GUI(self) -> str: cs = self.get_state() if cs <= ChannelState.OPEN and self.unconfirmed_closing_txid: return 'FORCE-CLOSING' return cs.name @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 get_local_pubkey(self) -> bytes: """Returns our node ID.""" pass @abstractmethod def get_capacity(self) -> Optional[int]: """Returns channel capacity in satoshis, or None if unknown.""" pass @abstractmethod def can_be_deleted(self) -> bool: pass @abstractmethod def get_wallet_addresses_channel_might_want_reserved(self) -> Sequence[str]: """Returns a list of addrs that the wallet should not use, to avoid address-reuse. Typically, these addresses are wallet.is_mine, but that is not guaranteed, in which case the wallet can just ignore those. """ pass def has_anchors(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, *, lnworker=None): self.name = None self.cb = cb self.is_imported = isinstance(self.cb, ImportedChannelBackupStorage) self.storage = {} # dummy storage self._state = ChannelState.OPENING self.node_id = cb.node_id if self.is_imported else cb.node_id_prefix self.channel_id = cb.channel_id() self.funding_outpoint = cb.funding_outpoint() self.lnworker = lnworker self.short_channel_id = None Logger.__init__(self) self.config = {} if self.is_imported: assert isinstance(cb, ImportedChannelBackupStorage) self.init_config(cb) self.unconfirmed_closing_txid = None # not a state, only for GUI def init_config(self, cb: ImportedChannelBackupStorage): local_payment_pubkey = cb.local_payment_pubkey if local_payment_pubkey is None: self.logger.warning( f"local_payment_pubkey missing from (old-type) channel backup. " f"You should export and re-import a newer backup.") multisig_funding_keypair = None if multisig_funding_secret := cb.multisig_funding_privkey: multisig_funding_keypair = Keypair( privkey=multisig_funding_secret, pubkey=ecc.ECPrivkey(multisig_funding_secret).get_public_key_bytes(), ) self.config[LOCAL] = LocalConfig.from_seed( channel_seed=cb.channel_seed, to_self_delay=cb.local_delay, # there are three cases of backups: # 1. legacy: payment_basepoint will be derived # 2. static_remotekey: to_remote sweep not necessary due to wallet address # 3. anchor outputs: sweep to_remote by deriving the key from the funding pubkeys static_remotekey=local_payment_pubkey, multisig_key=multisig_funding_keypair, # dummy values static_payment_key=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, current_commitment_signature=None, current_htlc_signatures=b'', htlc_minimum_msat=1, upfront_shutdown_script='', announcement_node_sig=b'', announcement_bitcoin_sig=b'', ) self.config[REMOTE] = RemoteConfig( # payment_basepoint needed to deobfuscate ctn in our_ctx payment_basepoint=OnlyPubkeyKeypair(cb.remote_payment_pubkey), # revocation_basepoint is used to claim to_local in our ctx 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='', announcement_node_sig=b'', announcement_bitcoin_sig=b'', ) def can_be_deleted(self): return self.is_imported or self.is_redeemed() def get_capacity(self): lnwatcher = self.lnworker.lnwatcher if lnwatcher: # fixme: we should probably not call that method here return lnwatcher.adb.get_tx_delta(self.funding_outpoint.txid, self.cb.funding_address) return None def is_backup(self): return True def create_sweeptxs_for_their_ctx(self, ctx): funding_tx = self.get_funding_tx() assert funding_tx return sweep_their_ctx_to_remote_backup(chan=self, ctx=ctx, funding_tx=funding_tx) def create_sweeptxs_for_our_ctx(self, ctx): if self.is_imported: return sweep_our_ctx(chan=self, ctx=ctx) else: return {} def maybe_sweep_htlcs(self, ctx: Transaction, htlc_tx: Transaction) -> Dict[str, SweepInfo]: return {} def extract_preimage_from_htlc_txin(self, txin: TxInput, *, is_deeply_mined: bool) -> None: return None def get_funding_address(self): return self.cb.funding_address def is_initiator(self): return self.cb.is_initiator def is_public(self): return False 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 get_sweep_address(self) -> str: return self.lnworker.wallet.get_new_sweep_address_for_channel() def has_anchors(self) -> Optional[bool]: return None def is_zeroconf(self) -> bool: return False def remove_zeroconf_flag(self) -> None: pass def get_local_pubkey(self) -> bytes: cb = self.cb assert isinstance(cb, ChannelBackupStorage) if isinstance(cb, ImportedChannelBackupStorage): return ecc.ECPrivkey(cb.privkey).get_public_key_bytes(compressed=True) if isinstance(cb, OnchainChannelBackupStorage): return self.lnworker.node_keypair.pubkey raise NotImplementedError(f"unexpected cb type: {type(cb)}") def get_close_options(self) -> Sequence[ChanCloseOption]: ret = [] if self.get_state() == ChannelState.FUNDED: ret.append(ChanCloseOption.REQUEST_REMOTE_FCLOSE) return ret def get_wallet_addresses_channel_might_want_reserved(self) -> Sequence[str]: if self.is_imported: # For v1 imported cbs, we have the local_payment_pubkey, which is # directly used as p2wpkh() of static_remotekey channels. # (for v0 imported cbs, the correct local_payment_pubkey is missing, and so # we might calculate a different address here, which might not be wallet.is_mine, # but that should be harmless) our_payment_pubkey = self.config[LOCAL].payment_basepoint.pubkey to_remote_address = make_commitment_output_to_remote_address(our_payment_pubkey, has_anchors=self.has_anchors()) return [to_remote_address] else: # on-chain backup return [] 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 ^ # our forwarding parameters for forwarding HTLCs through this channel forwarding_cltv_delta = 144 forwarding_fee_base_msat = 1000 forwarding_fee_proportional_millionths = 1 def __repr__(self): return "Channel(%s)"%self.get_id_for_log() def __init__(self, state: 'StoredDict', *, name=None, lnworker=None, initial_feerate=None, opening_fee=None): self.opening_fee = opening_fee self.name = name self.channel_id = bfh(state["channel_id"]) self.short_channel_id = ShortChannelID.normalize(state["short_channel_id"]) Logger.__init__(self) # should be after short_channel_id is set self.lnworker = lnworker self.storage = state self.db_lock = self.storage.lock self.config = {} self.config[LOCAL] = state["local_config"] self.config[REMOTE] = state["remote_config"] self.constraints = state["constraints"] # type: ChannelConstraints self.funding_outpoint = state["funding_outpoint"] self.node_id = bfh(state["node_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.unfulfilled_htlcs = state["unfulfilled_htlcs"] # type: Dict[int, Tuple[str, Optional[str]]] # ^ htlc_id -> onion_packet_hex, forwarding_key self._state = ChannelState[state['state']] self.peer_state = PeerState.DISCONNECTED self._outgoing_channel_update = 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, OnionRoutingFailure)] self.unconfirmed_closing_txid = None # not a state, only for GUI self.sent_channel_ready = False # no need to persist this, because channel_ready is re-sent in channel_reestablish self.sent_announcement_signatures = False self.htlc_settle_time = {} def get_local_scid_alias(self, *, create_new_if_needed: bool = False) -> Optional[bytes]: """Get scid_alias to be used for *outgoing* HTLCs. (called local as we choose the value) """ if alias := self.storage.get('local_scid_alias'): return bytes.fromhex(alias) elif create_new_if_needed: # deterministic, same secrecy level as wallet master pubkey wallet_fingerprint = bytes(self.lnworker.wallet.get_fingerprint(), "utf8") alias = sha256(wallet_fingerprint + self.channel_id)[0:8] self.storage['local_scid_alias'] = alias.hex() return alias return None def save_remote_scid_alias(self, alias: bytes): self.storage['alias'] = alias.hex() def get_remote_scid_alias(self) -> Optional[bytes]: """Get scid_alias to be used for *incoming* HTLCs. (called remote as the remote chooses the value) """ alias = self.storage.get('alias') return bytes.fromhex(alias) if alias else None def get_scid_or_local_alias(self): return self.short_channel_id or self.get_local_scid_alias() def has_onchain_backup(self): return self.storage.get('has_onchain_backup', False) def can_be_deleted(self): return self.is_redeemed() def get_capacity(self): return self.constraints.capacity def is_public(self): return bool(self.constraints.flags & CF_ANNOUNCE_CHANNEL) 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) return super().diagnostic_name() def set_onion_key(self, key: int, value: bytes): self.onion_keys[key] = value def pop_onion_key(self, key: int) -> bytes: return self.onion_keys.pop(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, payload: dict) -> None: """Save the ChannelUpdate message for the incoming direction of this channel. This message contains info we need to populate private route hints when creating invoices. """ assert payload['short_channel_id'] in [self.short_channel_id, self.get_local_scid_alias()] from .channel_db import ChannelDB ChannelDB.verify_channel_update(payload, start_node=self.node_id) raw = payload['raw'] 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'] = {} 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 save_remote_peer_sent_error(self, original_error: bytes): # We save the original arbitrary text(/bytes) error, as received. # The length is only implicitly limited by the BOLT-08 max msg size. # Receiving an error usually results in the channel getting closed, so # there is likely no need to store multiple errors. We only store one, and overwrite. self.storage['remote_peer_sent_error'] = original_error.hex() def get_remote_peer_sent_error(self) -> Optional[str]: original_error = self.storage.get('remote_peer_sent_error') if not original_error: return None err_bytes = bytes.fromhex(original_error) safe_str = error_text_bytes_to_safe_str(err_bytes) # note: truncates return safe_str def get_outgoing_gossip_channel_update(self, *, scid: ShortChannelID = None) -> bytes: """ scid: to be put into the channel_update message instead of the real scid, as this might be an scid alias """ if self._outgoing_channel_update is not None and scid is None: return self._outgoing_channel_update if not self.lnworker: raise Exception('lnworker not set for channel!') if scid is None: scid = self.short_channel_id 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' 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=scid, channel_flags=channel_flags, message_flags=b'\x01', cltv_expiry_delta=self.forwarding_cltv_delta, htlc_minimum_msat=self.config[REMOTE].htlc_minimum_msat, htlc_maximum_msat=htlc_maximum_msat, fee_base_msat=self.forwarding_fee_base_msat, fee_proportional_millionths=self.forwarding_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).ecdsa_sign(sighash, sigencode=ecc.ecdsa_sig64_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) -> Tuple[bytes, bool]: bitcoin_keys = [ self.config[REMOTE].multisig_key.pubkey, self.config[LOCAL].multisig_key.pubkey] node_ids = [self.node_id, self.get_local_pubkey()] is_reverse = node_ids[0] > node_ids[1] if is_reverse: node_ids.reverse() 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], ) return chan_ann, is_reverse def get_channel_announcement_hash(self): chan_ann, _ = self.construct_channel_announcement_without_sigs() return sha256d(chan_ann[256+2:]) def is_static_remotekey_enabled(self) -> bool: channel_type = ChannelType(self.storage.get('channel_type')) return bool(channel_type & ChannelType.OPTION_STATIC_REMOTEKEY) def is_zeroconf(self) -> bool: channel_type = ChannelType(self.storage.get('channel_type')) return bool(channel_type & ChannelType.OPTION_ZEROCONF) def remove_zeroconf_flag(self) -> None: if not self.is_zeroconf(): return channel_type = ChannelType(self.storage.get('channel_type')) self.storage['channel_type'] = channel_type & ~ChannelType.OPTION_ZEROCONF def get_sweep_address(self) -> str: # TODO: in case of unilateral close with pending HTLCs, this address will be reused if self.has_anchors(): addr = self.lnworker.wallet.get_new_sweep_address_for_channel() elif self.is_static_remotekey_enabled(): our_payment_pubkey = self.config[LOCAL].payment_basepoint.pubkey addr = make_commitment_output_to_remote_address(our_payment_pubkey, has_anchors=self.has_anchors()) if self.lnworker: assert self.lnworker.wallet.is_mine(addr) return addr def has_anchors(self) -> bool: channel_type = ChannelType(self.storage.get('channel_type')) return bool(channel_type & ChannelType.OPTION_ANCHORS_ZERO_FEE_HTLC_TX) def get_wallet_addresses_channel_might_want_reserved(self) -> Sequence[str]: assert 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, has_anchors=self.has_anchors()) return [to_remote_address] 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, status=None) -> Mapping[bytes, List[HTLCWithStatus]]: 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_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' if status and status != _status: continue htlc_with_status = HTLCWithStatus( channel_id=self.channel_id, htlc=htlc, direction=direction, status=_status) out[htlc.payment_hash].append(htlc_with_status) 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): cs_name = super().get_state_for_GUI() if self.is_closed() or self.unconfirmed_closing_txid: 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_update_ctx(self, *, proposer: HTLCOwner) -> bool: """Whether proposer is allowed to send commitment_signed, revoke_and_ack, and update_* messages. """ if self.get_state() not in (ChannelState.OPEN, ChannelState.SHUTDOWN): return False if self.peer_state != PeerState.GOOD: return False if proposer == LOCAL: if not self._can_send_ctx_updates: return False return True def can_send_update_add_htlc(self) -> bool: return self.can_update_ctx(proposer=LOCAL) and self.is_open() def is_frozen_for_sending(self) -> bool: if self.lnworker and self.lnworker.uses_trampoline() and not self.lnworker.is_trampoline_peer(self.node_id): return True 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: if self.lnworker and self.lnworker.uses_trampoline() and not self.lnworker.is_trampoline_peer(self.node_id): return True 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(f"Channel not open. {self.get_state()!r}") if not self.can_update_ctx(proposer=htlc_proposer): raise PaymentFailure(f"cannot update channel. {self.get_state()!r} {self.peer_state!r}") if htlc_proposer == LOCAL: if not self.can_send_update_add_htlc(): raise PaymentFailure('Channel cannot add htlc') # 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 self.htlc_slots_left(htlc_proposer) == 0: raise PaymentFailure('Too many HTLCs already in channel') if amount_msat > self.remaining_max_inflight(htlc_receiver, strict=False): raise PaymentFailure( f'HTLC value sum (sum of pending htlcs plus new htlc) ' f'would exceed max allowed: {chan_config.max_htlc_value_in_flight_msat/1000} sat') # check proposer can afford htlc max_can_send_msat = self.available_to_spend(htlc_proposer) if max_can_send_msat < amount_msat: raise PaymentFailure(f'Not enough balance. can send: {max_can_send_msat}, tried: {amount_msat}') def htlc_slots_left(self, htlc_proposer: HTLCOwner) -> int: # check "max_accepted_htlcs" htlc_receiver = htlc_proposer.inverted() ctn = self.get_next_ctn(htlc_receiver) chan_config = self.config[htlc_receiver] # 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) if not strict: # this is the loose check BOLT-02 specifies: return chan_config.max_accepted_htlcs - len(self.hm.htlcs_by_direction(htlc_receiver, direction=RECEIVED, ctn=ctn)) else: # however, c-lightning is a lot stricter, so extra checks: # https://github.com/ElementsProject/lightning/blob/4dcd4ca1556b13b6964a10040ba1d5ef82de4788/channeld/full_channel.c#L581 max_concurrent_htlcs = min( self.config[htlc_proposer].max_accepted_htlcs, self.config[htlc_receiver].max_accepted_htlcs) return max_concurrent_htlcs - len(self.hm.htlcs(htlc_receiver, ctn=ctn)) def remaining_max_inflight(self, htlc_receiver: HTLCOwner, *, strict: bool) -> int: """ Checks max_htlc_value_in_flight_msat strict = False -> how much we can accept according to BOLT2 strict = True -> how much the remote will accept to send to us (Eclair has stricter rules) """ ctn = self.get_next_ctn(htlc_receiver) current_htlc_sum = htlcsum(self.hm.htlcs_by_direction(htlc_receiver, direction=RECEIVED, ctn=ctn).values()) max_inflight = self.config[htlc_receiver].max_htlc_value_in_flight_msat if strict and htlc_receiver == LOCAL: # in order to send, eclair applies both local and remote max values # https://github.com/ACINQ/eclair/blob/9b0c00a2a28d3ba6c7f3d01fbd2d8704ebbdc75d/eclair-core/src/main/scala/fr/acinq/eclair/channel/Commitments.scala#L503 max_inflight = min( self.config[LOCAL].max_htlc_value_in_flight_msat, self.config[REMOTE].max_htlc_value_in_flight_msat ) return max_inflight - current_htlc_sum 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: if self.peer_state != PeerState.DISCONNECTED: return False if self.should_request_force_close: return True return ChannelState.PREOPENING < self._state < ChannelState.CLOSING 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. """ assert isinstance(htlc, UpdateAddHtlc) self._assert_can_add_htlc(htlc_proposer=LOCAL, amount_msat=htlc.amount_msat) if htlc.htlc_id is None: htlc = dataclasses.replace(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. """ 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 = dataclasses.replace(htlc, htlc_id=self.hm.get_next_htlc_id(REMOTE)) with self.db_lock: self.hm.recv_htlc(htlc) if onion_packet: self.unfulfilled_htlcs[htlc.htlc_id] = onion_packet.hex(), None 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. """ # TODO: when more channel types are supported, this method should depend on channel type next_remote_ctn = self.get_next_ctn(REMOTE) self.logger.info(f"sign_next_commitment. ctn={next_remote_ctn}") assert not self.is_closed(), self.get_state() pending_remote_commitment = self.get_next_commitment(REMOTE) sig_64 = sign_and_get_sig_string(pending_remote_commitment, self.config[LOCAL], self.config[REMOTE]) self.logger.debug(f"sign_next_commitment. {pending_remote_commitment.serialize()=}. {sig_64.hex()=}") 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) if self.has_anchors(): # we send a signature with the following sighash flags # for the peer to be able to replace inputs and outputs htlc_tx.inputs()[0].sighash = Sighash.ANYONECANPAY | Sighash.SINGLE sig = htlc_tx.sign_txin(0, their_remote_htlc_privkey) htlc_sig = ecc.ecdsa_sig64_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) # TODO: when more channel types are supported, this method should depend on channel type 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 not self.is_closed(), self.get_state() assert len(htlc_sigs) == 0 or type(htlc_sigs[0]) is bytes pending_local_commitment = self.get_next_commitment(LOCAL) pre_hash = pending_local_commitment.serialize_preimage(0) msg_hash = sha256d(pre_hash) if not ECPubkey(self.config[REMOTE].multisig_key.pubkey).ecdsa_verify(sig, msg_hash): raise LNProtocolWarning( f'failed verifying signature for our updated commitment transaction. ' f'sig={sig.hex()}. ' f'msg_hash={msg_hash.hex()}. ' f'pubkey={self.config[REMOTE].multisig_key.pubkey}. ' f'ctx={pending_local_commitment.serialize()} ' ) 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 LNProtocolWarning(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) if self.has_anchors(): # peer sent us a signature for our ctx using anchor sighash flags htlc_tx.inputs()[0].sighash = Sighash.ANYONECANPAY | Sighash.SINGLE pre_hash = htlc_tx.serialize_preimage(0) msg_hash = sha256d(pre_hash) remote_htlc_pubkey = derive_pubkey(self.config[REMOTE].htlc_basepoint.pubkey, pcp) if not ECPubkey(remote_htlc_pubkey).ecdsa_verify(htlc_sig, msg_hash): raise LNProtocolWarning( f'failed verifying HTLC signatures: {htlc=}, {htlc_direction=}. ' f'htlc_tx={htlc_tx.serialize()}. ' f'htlc_sig={htlc_sig.hex()}. ' f'remote_htlc_pubkey={remote_htlc_pubkey.hex()}. ' f'msg_hash={msg_hash.hex()}. ' f'ctx={ctx.serialize()}. ' f'ctx_output_idx={ctx_output_idx}. ' f'ctn={ctn}. ' ) 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_sighash = Sighash.ALL if not self.has_anchors() else Sighash.ANYONECANPAY | Sighash.SINGLE remote_htlc_sig = ecc.ecdsa_der_sig_from_ecdsa_sig64(htlc_sig) + Sighash.to_sigbytes(remote_sighash) return remote_htlc_sig def revoke_current_commitment(self): self.logger.info("revoke_current_commitment") assert not self.is_closed(), self.get_state() 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() 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") assert not self.is_closed(), self.get_state() 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 assert new_ctn == self.get_oldest_unrevoked_ctn(REMOTE) # lnworker callbacks if self.lnworker: sent = self.hm.sent_in_ctn(new_ctn) for htlc in sent: self.lnworker.htlc_fulfilled(self, htlc.payment_hash, htlc.htlc_id) 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 self.lnworker.htlc_failed(self, htlc.payment_hash, htlc.htlc_id, error_bytes, failure_message) def extract_preimage_from_htlc_txin(self, txin: TxInput, *, is_deeply_mined: bool) -> None: from . import lnutil from .crypto import ripemd from .transaction import match_script_against_template, script_GetOp from .lnonion import OnionRoutingFailure, OnionFailureCode witness = txin.witness_elements() witness_script = witness[-1] script_ops = [x for x in script_GetOp(witness_script)] if match_script_against_template(witness_script, lnutil.WITNESS_TEMPLATE_OFFERED_HTLC, debug=False) \ or match_script_against_template(witness_script, lnutil.WITNESS_TEMPLATE_OFFERED_HTLC_ANCHORS, debug=False): ripemd_payment_hash = script_ops[21][1] elif match_script_against_template(witness_script, lnutil.WITNESS_TEMPLATE_RECEIVED_HTLC, debug=False) \ or match_script_against_template(witness_script, lnutil.WITNESS_TEMPLATE_RECEIVED_HTLC_ANCHORS, debug=False): ripemd_payment_hash = script_ops[14][1] else: return found = {} for direction, htlc in itertools.chain( self.hm.get_htlcs_in_oldest_unrevoked_ctx(REMOTE), self.hm.get_htlcs_in_latest_ctx(REMOTE)): if ripemd(htlc.payment_hash) == ripemd_payment_hash: is_sent = direction == RECEIVED found[htlc.htlc_id] = (htlc, is_sent) for direction, htlc in itertools.chain( self.hm.get_htlcs_in_oldest_unrevoked_ctx(LOCAL), self.hm.get_htlcs_in_latest_ctx(LOCAL)): if ripemd(htlc.payment_hash) == ripemd_payment_hash: is_sent = direction == SENT found[htlc.htlc_id] = (htlc, is_sent) if not found: return if len(witness) == 5: # HTLC success tx preimage = witness[3] elif len(witness) == 3: # spending offered HTLC directly from ctx preimage = witness[1] else: preimage = None # HTLC timeout tx if preimage: assert ripemd(sha256(preimage)) == ripemd_payment_hash payment_hash = sha256(preimage) if self.lnworker.get_preimage(payment_hash) is not None: return # ^ note: log message text grepped for in regtests self.logger.info(f"found preimage in witness of length {len(witness)}, for {payment_hash.hex()}") # Mark the htlc as fulfilled or failed. # If we forwarded this, this ensures that the success/failure is propagated back on the incoming channel. # FIXME we only look at outgoing htlcs that have a corresponding output in the commitment tx, # however we should also look at those that do not. E.g. a small value htlc might not create an output # but we should still propagate back success or failure on the incoming link. And it is not just about # small value htlcs: even a large htlc might not appear in the outgoing channel's ctx, e.g. maybe it was # not committed yet - we should still make sure it gets removed on the incoming channel. (see #9631) if preimage: self.lnworker.save_preimage(payment_hash, preimage) for htlc, is_sent in found.values(): if is_sent: self.lnworker.htlc_fulfilled(self, payment_hash, htlc.htlc_id) else: # htlc timeout tx if not is_deeply_mined: return failure = OnionRoutingFailure(code=OnionFailureCode.PERMANENT_CHANNEL_FAILURE, data=b'') for htlc, is_sent in found.values(): if is_sent: self.logger.info(f'htlc timeout tx: failing htlc {is_sent}') self.lnworker.htlc_failed( self, payment_hash=htlc.payment_hash, htlc_id=htlc.htlc_id, error_bytes=None, failure_message=failure) 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 has_unsettled_htlcs(self) -> bool: return len(self.hm.htlcs(LOCAL)) + len(self.hm.htlcs(REMOTE)) > 0 def available_to_spend(self, subject: HTLCOwner) -> int: """The usable balance of 'subject' in msat, after taking reserve and fees (and anchors) 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 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, has_anchors=self.has_anchors() ) 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, has_anchors=self.has_anchors()) * 1000 # the sender cannot spend below its reserve max_send_msat = sender_balance_msat - sender_reserve_msat # reserve a fee spike buffer # see https://github.com/lightningnetwork/lightning-rfc/pull/740 if sender == initiator == LOCAL: 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, has_anchors=self.has_anchors())[sender] max_send_msat -= fee_spike_buffer # we can't enforce the fee spike buffer on the remote party elif sender == initiator == REMOTE: max_send_msat -= ctx_fees_msat[sender] # initiator pays for anchor outputs if sender == initiator and self.has_anchors(): max_send_msat -= 2 * FIXED_ANCHOR_SAT * 1000 # handle the transaction fees for the HTLC transaction if is_htlc_dust: # nobody pays additional HTLC transaction fees return min(max_send_msat, htlc_trim_threshold_msat - 1) else: # somebody has to pay for the additional HTLC transaction fees if sender == initiator: return max_send_msat - htlc_fee_msat else: # check if the receiver can afford to pay for the HTLC transaction fees new_receiver_balance = receiver_balance_msat - receiver_reserve_msat - ctx_fees_msat[receiver] - htlc_fee_msat if self.has_anchors(): new_receiver_balance -= 2 * FIXED_ANCHOR_SAT * 1000 if new_receiver_balance < 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 = min(max_send_msat, self.remaining_max_inflight(receiver, strict=True)) if self.htlc_slots_left(sender) == 0: max_send_msat = 0 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) -> List[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, has_anchors=self.has_anchors()) else: threshold_sat = offered_htlc_trim_threshold_sat(dust_limit_sat=conf.dust_limit_sat, feerate=feerate, has_anchors=self.has_anchors()) 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_for_watchtower(self, ctn: int) -> List[Transaction]: from .lnsweep import sweep_their_ctx_watchtower from .fee_policy import FeePolicy from .transaction import PartialTxOutput, PartialTransaction secret, ctx = self.get_secret_and_commitment(REMOTE, ctn=ctn) txs = [] txins = sweep_their_ctx_watchtower(self, ctx, secret) fee_policy = FeePolicy('eta:2') for txin in txins: output_idx = txin.prevout.out_idx value = ctx.outputs()[output_idx].value tx_size_bytes = 121 fee = fee_policy.estimate_fee(tx_size_bytes, network=self.lnworker.network, allow_fallback_to_static_rates=True) outvalue = value - fee sweep_outputs = [PartialTxOutput.from_address_and_value(self.get_sweep_address(), outvalue)] sweep_tx = PartialTransaction.from_io([txin], sweep_outputs, version=2) sig = sweep_tx.sign_txin(0, txin.privkey) txin.witness = txin.make_witness(sig) txs.append(sweep_tx) return txs 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_update_ctx(proposer=LOCAL), f"cannot update channel. {self.get_state()!r} {self.peer_state!r}" htlc = self.hm.get_htlc_by_id(REMOTE, htlc_id) if htlc.payment_hash != sha256(preimage): raise Exception("incorrect preimage for HTLC") assert htlc_id not in self.hm.log[REMOTE]['settles'] self.hm.send_settle(htlc_id) self.htlc_settle_time[htlc_id] = now() def get_payment_hash(self, htlc_id: int) -> bytes: htlc = self.hm.get_htlc_by_id(LOCAL, htlc_id) return htlc.payment_hash 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") assert self.can_update_ctx(proposer=REMOTE), f"cannot update channel. {self.get_state()!r} {self.peer_state!r}" htlc = self.hm.get_htlc_by_id(LOCAL, htlc_id) if htlc.payment_hash != sha256(preimage): raise RemoteMisbehaving("received incorrect preimage for HTLC") 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_update_ctx(proposer=LOCAL), 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[OnionRoutingFailure] = None) -> None: """Fail a pending offered HTLC. Action must be initiated by REMOTE. """ self.logger.info("receive_fail_htlc") assert self.can_update_ctx(proposer=REMOTE), f"cannot update channel. {self.get_state()!r} {self.peer_state!r}" 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}") if feerate < FEERATE_PER_KW_MIN_RELAY_LIGHTNING: raise Exception(f"Cannot update_fee: feerate lower than min relay fee. {feerate} sat/kw. 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, has_anchors=self.has_anchors() ) 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.") assert self.can_update_ctx(proposer=LOCAL if from_us else REMOTE), f"cannot update channel. {self.get_state()!r} {self.peer_state!r}. {from_us=}" with self.db_lock: if from_us: 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_abs=htlc.cltv_abs, has_anchors=self.has_anchors()), 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), has_anchors=self.has_anchors(), ) assert self.is_static_remotekey_enabled() payment_pubkey = other_config.payment_basepoint.pubkey 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, has_anchors=self.has_anchors() ) 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=local_script, remote_script=remote_script, htlcs=[], dust_limit_sat=self.config[LOCAL].dust_limit_sat, has_anchors=self.has_anchors(), local_anchor_script=None, remote_anchor_script=None, ) 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 = closing_tx.sign_txin(0, self.config[LOCAL].multisig_key.privkey) sig = ecc.ecdsa_sig64_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 pre_hash = tx.serialize_preimage(0) msg_hash = sha256d(pre_hash) assert remote_sig res = ECPubkey(self.config[REMOTE].multisig_key.pubkey).ecdsa_verify(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({self.config[LOCAL].multisig_key.pubkey: self.config[LOCAL].multisig_key.privkey}) remote_sig = self.config[LOCAL].current_commitment_signature remote_sig = ecc.ecdsa_der_sig_from_ecdsa_sig64(remote_sig) + Sighash.to_sigbytes(Sighash.ALL) tx.add_signature_to_txin(txin_idx=0, signing_pubkey=self.config[REMOTE].multisig_key.pubkey, sig=remote_sig) assert tx.is_complete() return tx def get_close_options(self) -> Sequence[ChanCloseOption]: # This method is used both in the GUI, and in lnpeer.schedule_force_closing # in the latter case, the result does not depend on peer_state ret = [] if not self.is_closed() and self.peer_state == PeerState.GOOD: # If there are unsettled HTLCs, although is possible to cooperatively close, # we choose not to expose that option in the GUI, because it is very likely # that HTLCs will take a long time to settle (submarine swap, or stuck payment), # and the close dialog would be taking a very long time to finish if not self.has_unsettled_htlcs(): ret.append(ChanCloseOption.COOP_CLOSE) ret.append(ChanCloseOption.REQUEST_REMOTE_FCLOSE) if self.get_state() == ChannelState.WE_ARE_TOXIC: ret.append(ChanCloseOption.REQUEST_REMOTE_FCLOSE) if not self.is_closed() or self.get_state() == ChannelState.REQUESTED_FCLOSE: ret.append(ChanCloseOption.LOCAL_FCLOSE) assert not (self.get_state() == ChannelState.WE_ARE_TOXIC and ChanCloseOption.LOCAL_FCLOSE in ret), "local force-close unsafe if we are toxic" return ret def maybe_sweep_htlcs(self, ctx: Transaction, htlc_tx: Transaction) -> Dict[str, SweepInfo]: # look at the output address, check if it matches d = sweep_their_htlctx_justice(self, ctx, htlc_tx) d2 = sweep_our_htlctx(self, ctx, htlc_tx) d.update(d2) return d 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: int) -> 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_delta = lnutil.NBLOCK_DEADLINE_DELTA_BEFORE_EXPIRY_FOR_RECEIVED_HTLCS for sub, dir, ctn in ((LOCAL, RECEIVED, self.get_latest_ctn(LOCAL)), (REMOTE, SENT, self.get_oldest_unrevoked_ctn(REMOTE)), (REMOTE, SENT, self.get_latest_ctn(REMOTE)),): 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_abs - recv_htlc_deadline_delta > local_height: continue # Do not force-close if we just sent fulfill_htlc and have not received revack yet if htlc_id in self.htlc_settle_time and now() - self.htlc_settle_time[htlc_id] < 30: 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_delta = lnutil.NBLOCK_DEADLINE_DELTA_AFTER_EXPIRY_FOR_OFFERED_HTLCS for sub, dir, ctn in ((LOCAL, SENT, self.get_latest_ctn(LOCAL)), (REMOTE, RECEIVED, self.get_oldest_unrevoked_ctn(REMOTE)), (REMOTE, RECEIVED, self.get_latest_ctn(REMOTE)),): for htlc_id, htlc in self.hm.htlcs_by_direction(subject=sub, direction=dir, ctn=ctn).items(): if htlc.cltv_abs + offered_htlc_deadline_delta > local_height: continue htlcs_we_could_reclaim[(SENT, htlc_id)] = htlc # Note: previously we used a threshold concept, "min_value_worth_closing_channel_over_sat", and # only force-closed the channel if the total value of these expiring htlcs was large enough. # However, if we are forwarding, and an outgoing htlc expires, we should always close # the outgoing channel (regardless of htlc value), so that we can propagate back the # removal of the htlc in the incoming channel. return len(htlcs_we_could_reclaim) > 0 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 or self.is_zeroconf() # check funding_tx amount and script funding_tx = self.lnworker.lnwatcher.adb.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