# Copyright (C) 2018 The Electrum developers # Distributed under the MIT software license, see the accompanying # file LICENCE or http://www.opensource.org/licenses/mit-license.php from typing import TYPE_CHECKING from .util import TxMinedInfo, BelowDustLimit from .util import EventListener, event_listener from .transaction import Transaction, TxOutpoint from .logging import Logger if TYPE_CHECKING: from .network import Network from .lnsweep import SweepInfo from .lnworker import LNWallet from .lnchannel import AbstractChannel class LNWatcher(Logger, EventListener): LOGGING_SHORTCUT = 'W' def __init__(self, lnworker: 'LNWallet'): self.lnworker = lnworker Logger.__init__(self) self.adb = lnworker.wallet.adb self.config = lnworker.config self.callbacks = {} # address -> lambda function self.network = None self.register_callbacks() # status gets populated when we run self.channel_status = {} def start_network(self, network: 'Network'): self.network = network def stop(self): self.unregister_callbacks() def get_channel_status(self, outpoint): return self.channel_status.get(outpoint, 'unknown') def remove_callback(self, address): self.callbacks.pop(address, None) def add_callback(self, address, callback): self.adb.add_address(address) self.callbacks[address] = callback def trigger_callbacks(self): if not self.adb.synchronizer: self.logger.info("synchronizer not set yet") return for address, callback in list(self.callbacks.items()): callback() @event_listener async def on_event_blockchain_updated(self, *args): # we invalidate the cache on each new block because # some processes affect the list of sweep transactions # (hold invoice preimage revealed, MPP completed, etc) for chan in self.lnworker.channels.values(): chan._sweep_info.clear() self.trigger_callbacks() @event_listener def on_event_wallet_updated(self, wallet): # called if we add local tx if wallet.adb != self.adb: return self.trigger_callbacks() @event_listener def on_event_adb_added_verified_tx(self, adb, tx_hash): if adb != self.adb: return self.trigger_callbacks() @event_listener def on_event_adb_set_up_to_date(self, adb): if adb != self.adb: return self.trigger_callbacks() def add_channel(self, chan: 'AbstractChannel') -> None: outpoint = chan.funding_outpoint.to_str() address = chan.get_funding_address() callback = lambda: self.check_onchain_situation(address, outpoint) callback() # run once, for side effects if chan.need_to_subscribe(): self.add_callback(address, callback) def unwatch_channel(self, address, funding_outpoint): self.logger.info(f'unwatching {funding_outpoint}') self.remove_callback(address) def check_onchain_situation(self, address, funding_outpoint): # early return if address has not been added yet if not self.adb.is_mine(address): return # inspect_tx_candidate might have added new addresses, in which case we return early funding_txid = funding_outpoint.split(':')[0] funding_height = self.adb.get_tx_height(funding_txid) closing_txid = self.adb.get_spender(funding_outpoint) closing_height = self.adb.get_tx_height(closing_txid) if closing_txid: closing_tx = self.adb.get_transaction(closing_txid) if closing_tx: keep_watching = self.sweep_commitment_transaction(funding_outpoint, closing_tx) else: self.logger.info(f"channel {funding_outpoint} closed by {closing_txid}. still waiting for tx itself...") keep_watching = True else: keep_watching = True self.update_channel_state( funding_outpoint=funding_outpoint, funding_txid=funding_txid, funding_height=funding_height, closing_txid=closing_txid, closing_height=closing_height, keep_watching=keep_watching) if not keep_watching: self.unwatch_channel(address, funding_outpoint) def diagnostic_name(self): return f"{self.lnworker.wallet.diagnostic_name()}-LNW" def update_channel_state(self, *, funding_outpoint: str, funding_txid: str, funding_height: TxMinedInfo, closing_txid: str, closing_height: TxMinedInfo, keep_watching: bool) -> None: chan = self.lnworker.channel_by_txo(funding_outpoint) if not chan: return chan.update_onchain_state( funding_txid=funding_txid, funding_height=funding_height, closing_txid=closing_txid, closing_height=closing_height, keep_watching=keep_watching) self.lnworker.handle_onchain_state(chan) def sweep_commitment_transaction(self, funding_outpoint, closing_tx) -> bool: """This function is called when a channel was closed. In this case we need to check for redeemable outputs of the commitment transaction or spenders down the line (HTLC-timeout/success transactions). Returns whether we should continue to monitor. Side-effécts: - sets defaults labels - populates wallet._accounting_addresses """ chan = self.lnworker.channel_by_txo(funding_outpoint) if not chan: return False # detect who closed and get information about how to claim outputs sweep_info_dict = chan.sweep_ctx(closing_tx) keep_watching = False if sweep_info_dict else not self.adb.is_deeply_mined(closing_tx.txid()) # create and broadcast transactions for prevout, sweep_info in sweep_info_dict.items(): prev_txid, prev_index = prevout.split(':') name = sweep_info.name + ' ' + chan.get_id_for_log() self.lnworker.wallet.set_default_label(prevout, name) if not self.adb.get_transaction(prev_txid): # do not keep watching if prevout does not exist self.logger.info(f'prevout does not exist for {name}: {prevout}') continue spender_txid = self.adb.get_spender(prevout) spender_tx = self.adb.get_transaction(spender_txid) if spender_txid else None if spender_tx: # the spender might be the remote, revoked or not htlc_sweepinfo = chan.maybe_sweep_htlcs(closing_tx, spender_tx) for prevout2, htlc_sweep_info in htlc_sweepinfo.items(): htlc_tx_spender = self.adb.get_spender(prevout2) self.lnworker.wallet.set_default_label(prevout2, htlc_sweep_info.name) if htlc_tx_spender: keep_watching |= not self.adb.is_deeply_mined(htlc_tx_spender) self.maybe_add_accounting_address(htlc_tx_spender, htlc_sweep_info) else: keep_watching |= self.maybe_redeem(htlc_sweep_info) keep_watching |= not self.adb.is_deeply_mined(spender_txid) self.maybe_extract_preimage(chan, spender_tx, prevout) self.maybe_add_accounting_address(spender_txid, sweep_info) else: keep_watching |= self.maybe_redeem(sweep_info) return keep_watching def maybe_redeem(self, sweep_info: 'SweepInfo') -> bool: """ returns False if it was dust """ try: self.lnworker.wallet.txbatcher.add_sweep_input('lnwatcher', sweep_info, self.config.FEE_POLICY_LIGHTNING) except BelowDustLimit: return False return True def maybe_extract_preimage(self, chan: 'AbstractChannel', spender_tx: Transaction, prevout: str): txin_idx = spender_tx.get_input_idx_that_spent_prevout(TxOutpoint.from_str(prevout)) assert txin_idx is not None spender_txin = spender_tx.inputs()[txin_idx] chan.extract_preimage_from_htlc_txin( spender_txin, is_deeply_mined=self.adb.is_deeply_mined(spender_tx.txid()), ) def maybe_add_accounting_address(self, spender_txid: str, sweep_info: 'SweepInfo'): spender_tx = self.adb.get_transaction(spender_txid) if spender_txid else None if not spender_tx: return for i, txin in enumerate(spender_tx.inputs()): if txin.prevout == sweep_info.txin.prevout: break else: return if sweep_info.name in ['first-stage-htlc', 'first-stage-htlc-anchors']: # always consider ours pass else: privkey = sweep_info.txin.privkey witness = txin.witness_elements() for sig in witness: sig = witness[0] # fixme: verify sig is ours witness2 = sweep_info.txin.make_witness(sig) if txin.witness == witness2: break else: self.logger.info(f"signature not found {sweep_info.name}, {txin.prevout.to_str()}") return self.logger.info(f'adding txin address {sweep_info.name}, {txin.prevout.to_str()}') prev_txid, prev_index = txin.prevout.to_str().split(':') prev_tx = self.adb.get_transaction(prev_txid) txout = prev_tx.outputs()[int(prev_index)] self.lnworker.wallet._accounting_addresses.add(txout.address)