# 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'] 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) @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 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.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, ) 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) 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 True 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.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 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 subject in LOCAL, REMOTE: log = self.hm.log[subject] for htlc_id, htlc in log.get('adds', {}).items(): if htlc_id in log.get('fails',{}): status = 'failed' elif htlc_id in log.get('settles',{}): status = 'settled' else: status = 'inflight' direction = SENT if subject is LOCAL else RECEIVED rhash = bh2u(htlc.payment_hash) out.append((rhash, self.channel_id, htlc, direction, status)) return out def get_settled_payments(self): out = defaultdict(list) for subject in LOCAL, REMOTE: log = self.hm.log[subject] for htlc_id, htlc in log.get('adds', {}).items(): if htlc_id in log.get('settles',{}): direction = SENT if subject is LOCAL else RECEIVED rhash = bh2u(htlc.payment_hash) 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: error_bytes, failure_message = self._receive_fail_reasons.pop(htlc.htlc_id) # 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, error_bytes, failure_message): 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 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}" log = self.hm.log[REMOTE] htlc = log['adds'][htlc_id] assert htlc.payment_hash == sha256(preimage) assert htlc_id not in log['settles'] self.hm.send_settle(htlc_id) def get_payment_hash(self, htlc_id: int) -> bytes: log = self.hm.log[LOCAL] htlc = log['adds'][htlc_id] # type: UpdateAddHtlc 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") log = self.hm.log[LOCAL] htlc = log['adds'][htlc_id] assert htlc.payment_hash == sha256(preimage) assert htlc_id not in log['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_sender=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