895 lines
38 KiB
Python
895 lines
38 KiB
Python
# Copyright (C) 2018 The Electrum developers
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# Distributed under the MIT software license, see the accompanying
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# file LICENCE or http://www.opensource.org/licenses/mit-license.php
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from typing import Optional, Dict, List, Tuple, TYPE_CHECKING, NamedTuple, Callable
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from enum import Enum, auto
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from functools import partial
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import electrum_ecc as ecc
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from .util import bfh, UneconomicFee
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from .crypto import privkey_to_pubkey
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from .bitcoin import redeem_script_to_address, dust_threshold, construct_witness
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from .invoices import PR_PAID
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from . import descriptor
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from . import coinchooser
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from .lnutil import (make_commitment_output_to_remote_address, make_commitment_output_to_local_witness_script,
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derive_privkey, derive_pubkey, derive_blinded_pubkey, derive_blinded_privkey,
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make_htlc_tx_witness, make_htlc_tx_with_open_channel, UpdateAddHtlc,
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LOCAL, REMOTE, make_htlc_output_witness_script,
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get_ordered_channel_configs, get_per_commitment_secret_from_seed,
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RevocationStore, extract_ctn_from_tx_and_chan, UnableToDeriveSecret, SENT, RECEIVED,
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map_htlcs_to_ctx_output_idxs, Direction, make_commitment_output_to_remote_witness_script,
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derive_payment_basepoint, ctx_has_anchors, SCRIPT_TEMPLATE_FUNDING)
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from .transaction import (Transaction, TxInput, PartialTransaction, PartialTxInput,
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PartialTxOutput, TxOutpoint, script_GetOp, match_script_against_template)
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from .simple_config import SimpleConfig
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from .logging import get_logger, Logger
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if TYPE_CHECKING:
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from .lnchannel import Channel, AbstractChannel, ChannelBackup
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_logger = get_logger(__name__)
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# note: better to use chan.logger instead, when applicable
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HTLC_TRANSACTION_DEADLINE_FRACTION = 4
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HTLC_TRANSACTION_SWEEP_TARGET = 10
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HTLCTX_INPUT_OUTPUT_INDEX = 0
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class SweepInfo(NamedTuple):
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name: str
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csv_delay: int
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cltv_abs: int
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gen_tx: Callable[[], Optional[Transaction]]
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def txs_their_ctx_watchtower(chan: 'Channel', ctx: Transaction, per_commitment_secret: bytes,
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sweep_address: str) -> List[Transaction]:
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"""Presign sweeping transactions using the just received revoked pcs.
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These will only be utilised if the remote breaches.
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Sweep 'to_local', and all the HTLCs (two cases: directly from ctx, or from HTLC tx).
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"""
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# prep
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ctn = extract_ctn_from_tx_and_chan(ctx, chan)
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pcp = ecc.ECPrivkey(per_commitment_secret).get_public_key_bytes(compressed=True)
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breacher_conf, watcher_conf = get_ordered_channel_configs(chan=chan, for_us=False)
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watcher_revocation_privkey = derive_blinded_privkey(
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watcher_conf.revocation_basepoint.privkey,
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per_commitment_secret
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)
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to_self_delay = watcher_conf.to_self_delay
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breacher_delayed_pubkey = derive_pubkey(breacher_conf.delayed_basepoint.pubkey, pcp)
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txs = []
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# create justice tx for breacher's to_local output
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revocation_pubkey = ecc.ECPrivkey(watcher_revocation_privkey).get_public_key_bytes(compressed=True)
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witness_script = make_commitment_output_to_local_witness_script(
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revocation_pubkey, to_self_delay, breacher_delayed_pubkey)
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to_local_address = redeem_script_to_address('p2wsh', witness_script)
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output_idxs = ctx.get_output_idxs_from_address(to_local_address)
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if output_idxs:
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output_idx = output_idxs.pop()
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sweep_tx = tx_ctx_to_local(
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sweep_address=sweep_address,
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ctx=ctx,
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output_idx=output_idx,
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witness_script=witness_script,
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privkey=watcher_revocation_privkey,
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is_revocation=True,
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config=chan.lnworker.config)
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if sweep_tx:
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txs.append(sweep_tx)
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# create justice txs for breacher's HTLC outputs
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breacher_htlc_pubkey = derive_pubkey(breacher_conf.htlc_basepoint.pubkey, pcp)
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watcher_htlc_pubkey = derive_pubkey(watcher_conf.htlc_basepoint.pubkey, pcp)
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def tx_htlc(
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htlc: 'UpdateAddHtlc', is_received_htlc: bool,
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ctx_output_idx: int) -> None:
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htlc_output_witness_script = make_htlc_output_witness_script(
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is_received_htlc=is_received_htlc,
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remote_revocation_pubkey=revocation_pubkey,
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remote_htlc_pubkey=watcher_htlc_pubkey,
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local_htlc_pubkey=breacher_htlc_pubkey,
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payment_hash=htlc.payment_hash,
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cltv_abs=htlc.cltv_abs,
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has_anchors=chan.has_anchors()
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)
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cltv_abs = htlc.cltv_abs if is_received_htlc else 0
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return tx_their_ctx_htlc(
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ctx=ctx,
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witness_script=htlc_output_witness_script,
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sweep_address=sweep_address,
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preimage=None,
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output_idx=ctx_output_idx,
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privkey=watcher_revocation_privkey,
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is_revocation=True,
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cltv_abs=cltv_abs,
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config=chan.lnworker.config,
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has_anchors=chan.has_anchors()
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)
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htlc_to_ctx_output_idx_map = map_htlcs_to_ctx_output_idxs(
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chan=chan,
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ctx=ctx,
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pcp=pcp,
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subject=REMOTE,
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ctn=ctn)
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for (direction, htlc), (ctx_output_idx, htlc_relative_idx) in htlc_to_ctx_output_idx_map.items():
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txs.append(
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tx_htlc(
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htlc=htlc,
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is_received_htlc=direction == RECEIVED,
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ctx_output_idx=ctx_output_idx)
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)
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# for anchor channels we don't know the HTLC transaction's txid beforehand due
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# to malleability because of ANYONECANPAY
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if chan.has_anchors():
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return txs
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# create justice transactions for HTLC transaction's outputs
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def txs_their_htlctx_justice(
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*,
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htlc: 'UpdateAddHtlc',
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htlc_direction: Direction,
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ctx_output_idx: int
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) -> Optional[Transaction]:
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htlc_tx_witness_script, htlc_tx = make_htlc_tx_with_open_channel(
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chan=chan,
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pcp=pcp,
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subject=REMOTE,
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ctn=ctn,
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htlc_direction=htlc_direction,
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commit=ctx,
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htlc=htlc,
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ctx_output_idx=ctx_output_idx)
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return tx_sweep_htlctx_output(
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htlc_tx=htlc_tx,
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output_idx=HTLCTX_INPUT_OUTPUT_INDEX,
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htlctx_witness_script=htlc_tx_witness_script,
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sweep_address=sweep_address,
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privkey=watcher_revocation_privkey,
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is_revocation=True,
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config=chan.lnworker.config)
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htlc_to_ctx_output_idx_map = map_htlcs_to_ctx_output_idxs(
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chan=chan,
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ctx=ctx,
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pcp=pcp,
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subject=REMOTE,
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ctn=ctn)
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for (direction, htlc), (ctx_output_idx, htlc_relative_idx) in htlc_to_ctx_output_idx_map.items():
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secondstage_sweep_tx = txs_their_htlctx_justice(
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htlc=htlc,
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htlc_direction=direction,
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ctx_output_idx=ctx_output_idx)
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if secondstage_sweep_tx:
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txs.append(secondstage_sweep_tx)
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return txs
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def tx_their_ctx_justice(
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chan: 'Channel',
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ctx: Transaction,
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per_commitment_secret: bytes,
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sweep_address: str) -> Optional[Callable[[], Optional[Transaction]]]:
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# prep
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pcp = ecc.ECPrivkey(per_commitment_secret).get_public_key_bytes(compressed=True)
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this_conf, other_conf = get_ordered_channel_configs(chan=chan, for_us=False)
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other_revocation_privkey = derive_blinded_privkey(other_conf.revocation_basepoint.privkey,
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per_commitment_secret)
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to_self_delay = other_conf.to_self_delay
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this_delayed_pubkey = derive_pubkey(this_conf.delayed_basepoint.pubkey, pcp)
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txs = []
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# to_local
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revocation_pubkey = ecc.ECPrivkey(other_revocation_privkey).get_public_key_bytes(compressed=True)
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witness_script = make_commitment_output_to_local_witness_script(
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revocation_pubkey, to_self_delay, this_delayed_pubkey)
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to_local_address = redeem_script_to_address('p2wsh', witness_script)
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output_idxs = ctx.get_output_idxs_from_address(to_local_address)
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if output_idxs:
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output_idx = output_idxs.pop()
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sweep_tx = lambda: tx_ctx_to_local(
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sweep_address=sweep_address,
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ctx=ctx,
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output_idx=output_idx,
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witness_script=witness_script,
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privkey=other_revocation_privkey,
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is_revocation=True,
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config=chan.lnworker.config)
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return sweep_tx
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return None
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def txs_their_htlctx_justice(
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chan: 'Channel',
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ctx: Transaction,
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htlc_tx: Transaction,
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sweep_address: str) -> Dict[int, SweepInfo]:
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"""Creates justice transactions for every output in the HTLC transaction.
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Due to anchor type channels it can happen that a remote party batches HTLC transactions,
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which is why this method can return multiple SweepInfos.
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"""
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x = extract_ctx_secrets(chan, ctx)
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if not x:
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return {}
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ctn, their_pcp, is_revocation, per_commitment_secret = x
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if not is_revocation:
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return {}
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# get HTLC constraints (secrets and locktime)
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pcp = ecc.ECPrivkey(per_commitment_secret).get_public_key_bytes(compressed=True)
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this_conf, other_conf = get_ordered_channel_configs(chan=chan, for_us=False)
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other_revocation_privkey = derive_blinded_privkey(
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other_conf.revocation_basepoint.privkey,
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per_commitment_secret)
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to_self_delay = other_conf.to_self_delay
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this_delayed_pubkey = derive_pubkey(this_conf.delayed_basepoint.pubkey, pcp)
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revocation_pubkey = ecc.ECPrivkey(other_revocation_privkey).get_public_key_bytes(compressed=True)
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# uses the same witness script as to_local
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witness_script = make_commitment_output_to_local_witness_script(
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revocation_pubkey, to_self_delay, this_delayed_pubkey)
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htlc_address = redeem_script_to_address('p2wsh', witness_script)
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# check that htlc transaction contains at least an output that is supposed to be
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# spent via a second stage htlc transaction
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htlc_outputs_idxs = [idx for idx, output in enumerate(htlc_tx.outputs()) if output.address == htlc_address]
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if not htlc_outputs_idxs:
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return {}
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# generate justice transactions
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def justice_tx(output_idx):
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return tx_sweep_htlctx_output(
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sweep_address=sweep_address,
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output_idx=output_idx,
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htlc_tx=htlc_tx,
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htlctx_witness_script=witness_script,
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privkey=other_revocation_privkey,
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is_revocation=True,
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config=chan.lnworker.config
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)
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index_to_sweepinfo = {}
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for output_idx in htlc_outputs_idxs:
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index_to_sweepinfo[output_idx] = SweepInfo(
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name='redeem_htlc2',
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csv_delay=0,
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cltv_abs=0,
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gen_tx=partial(justice_tx, output_idx)
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)
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return index_to_sweepinfo
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def txs_our_ctx(
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*, chan: 'AbstractChannel',
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ctx: Transaction,
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sweep_address: str) -> Optional[Dict[str, SweepInfo]]:
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"""Handle the case where we force-close unilaterally with our latest ctx.
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We sweep:
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to_local: CSV delayed
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htlc success: CSV delay with anchors, no delay otherwise
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htlc timeout: CSV delay with anchors, CLTV locktime
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second-stage htlc transactions: CSV delay
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'to_local' can be swept even if this is a breach (by us),
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but HTLCs cannot (old HTLCs are no longer stored).
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Outputs with CSV/CLTV are redeemed by LNWatcher.
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"""
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ctn = extract_ctn_from_tx_and_chan(ctx, chan)
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our_conf, their_conf = get_ordered_channel_configs(chan=chan, for_us=True)
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our_per_commitment_secret = get_per_commitment_secret_from_seed(
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our_conf.per_commitment_secret_seed, RevocationStore.START_INDEX - ctn)
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our_pcp = ecc.ECPrivkey(our_per_commitment_secret).get_public_key_bytes(compressed=True)
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our_delayed_bp_privkey = ecc.ECPrivkey(our_conf.delayed_basepoint.privkey)
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our_localdelayed_privkey = derive_privkey(our_delayed_bp_privkey.secret_scalar, our_pcp)
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our_localdelayed_privkey = ecc.ECPrivkey.from_secret_scalar(our_localdelayed_privkey)
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their_revocation_pubkey = derive_blinded_pubkey(their_conf.revocation_basepoint.pubkey, our_pcp)
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to_self_delay = their_conf.to_self_delay
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our_htlc_privkey = derive_privkey(secret=int.from_bytes(our_conf.htlc_basepoint.privkey, 'big'),
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per_commitment_point=our_pcp).to_bytes(32, 'big')
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our_localdelayed_pubkey = our_localdelayed_privkey.get_public_key_bytes(compressed=True)
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to_local_witness_script = make_commitment_output_to_local_witness_script(
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their_revocation_pubkey, to_self_delay, our_localdelayed_pubkey)
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to_local_address = redeem_script_to_address('p2wsh', to_local_witness_script)
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to_remote_address = None
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# test if this is our_ctx
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found_to_local = bool(ctx.get_output_idxs_from_address(to_local_address))
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if not chan.is_backup():
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assert chan.is_static_remotekey_enabled()
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their_payment_pubkey = their_conf.payment_basepoint.pubkey
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to_remote_address = make_commitment_output_to_remote_address(their_payment_pubkey, has_anchors=chan.has_anchors())
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found_to_remote = bool(ctx.get_output_idxs_from_address(to_remote_address))
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else:
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found_to_remote = False
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if not found_to_local and not found_to_remote:
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return
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chan.logger.debug(f'(lnsweep) found our ctx: {to_local_address} {to_remote_address}')
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# other outputs are htlcs
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# if they are spent, we need to generate the script
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# so, second-stage htlc sweep should not be returned here
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txs = {} # type: Dict[str, SweepInfo]
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# to_local
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output_idxs = ctx.get_output_idxs_from_address(to_local_address)
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if output_idxs:
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output_idx = output_idxs.pop()
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sweep_tx = lambda: tx_ctx_to_local(
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sweep_address=sweep_address,
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ctx=ctx,
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output_idx=output_idx,
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witness_script=to_local_witness_script,
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privkey=our_localdelayed_privkey.get_secret_bytes(),
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is_revocation=False,
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to_self_delay=to_self_delay,
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config=chan.lnworker.config)
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prevout = ctx.txid() + ':%d'%output_idx
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txs[prevout] = SweepInfo(
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name='our_ctx_to_local',
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csv_delay=to_self_delay,
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cltv_abs=0,
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gen_tx=sweep_tx)
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we_breached = ctn < chan.get_oldest_unrevoked_ctn(LOCAL)
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if we_breached:
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chan.logger.info(f"(lnsweep) we breached. txid: {ctx.txid()}")
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# return only our_ctx_to_local, because we don't keep htlc_signatures for old states
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return txs
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# HTLCs
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def txs_htlc(
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*, htlc: 'UpdateAddHtlc',
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htlc_direction: Direction,
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ctx_output_idx: int,
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htlc_relative_idx,
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preimage: Optional[bytes]):
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htlctx_witness_script, htlc_tx = tx_our_ctx_htlctx(
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chan=chan,
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our_pcp=our_pcp,
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ctx=ctx,
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htlc=htlc,
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local_htlc_privkey=our_htlc_privkey,
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preimage=preimage,
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htlc_direction=htlc_direction,
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ctx_output_idx=ctx_output_idx,
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htlc_relative_idx=htlc_relative_idx)
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# we sweep our ctx with HTLC transactions individually, therefore the CSV-locked output is always at
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# index TIMELOCKED_HTLCTX_OUTPUT_INDEX
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assert True
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sweep_tx = lambda: tx_sweep_htlctx_output(
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to_self_delay=to_self_delay,
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htlc_tx=htlc_tx,
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output_idx=HTLCTX_INPUT_OUTPUT_INDEX,
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htlctx_witness_script=htlctx_witness_script,
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sweep_address=sweep_address,
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privkey=our_localdelayed_privkey.get_secret_bytes(),
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is_revocation=False,
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config=chan.lnworker.config)
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# side effect
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txs[htlc_tx.inputs()[HTLCTX_INPUT_OUTPUT_INDEX].prevout.to_str()] = SweepInfo(
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name='first-stage-htlc',
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csv_delay=0,
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cltv_abs=htlc_tx.locktime,
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gen_tx=lambda: htlc_tx)
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txs[htlc_tx.txid() + f':{HTLCTX_INPUT_OUTPUT_INDEX}'] = SweepInfo(
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name='second-stage-htlc',
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csv_delay=to_self_delay,
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cltv_abs=0,
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gen_tx=sweep_tx)
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# offered HTLCs, in our ctx --> "timeout"
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# received HTLCs, in our ctx --> "success"
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htlc_to_ctx_output_idx_map = map_htlcs_to_ctx_output_idxs(
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chan=chan,
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ctx=ctx,
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pcp=our_pcp,
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subject=LOCAL,
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ctn=ctn)
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for (direction, htlc), (ctx_output_idx, htlc_relative_idx) in htlc_to_ctx_output_idx_map.items():
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if direction == RECEIVED:
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if not chan.lnworker.is_accepted_mpp(htlc.payment_hash):
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# do not redeem this, it might publish the preimage of an incomplete MPP
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continue
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preimage = chan.lnworker.get_preimage(htlc.payment_hash)
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if not preimage:
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# we might not have the preimage if this is a hold invoice
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continue
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else:
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preimage = None
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try:
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txs_htlc(
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htlc=htlc,
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htlc_direction=direction,
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ctx_output_idx=ctx_output_idx,
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htlc_relative_idx=htlc_relative_idx,
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preimage=preimage)
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except UneconomicFee:
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continue
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return txs
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|
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def extract_ctx_secrets(chan: 'Channel', ctx: Transaction):
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# note: the remote sometimes has two valid non-revoked commitment transactions,
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# either of which could be broadcast
|
|
our_conf, their_conf = get_ordered_channel_configs(chan=chan, for_us=True)
|
|
ctn = extract_ctn_from_tx_and_chan(ctx, chan)
|
|
per_commitment_secret = None
|
|
oldest_unrevoked_remote_ctn = chan.get_oldest_unrevoked_ctn(REMOTE)
|
|
if ctn == oldest_unrevoked_remote_ctn:
|
|
their_pcp = their_conf.current_per_commitment_point
|
|
is_revocation = False
|
|
elif ctn == oldest_unrevoked_remote_ctn + 1:
|
|
their_pcp = their_conf.next_per_commitment_point
|
|
is_revocation = False
|
|
elif ctn < oldest_unrevoked_remote_ctn: # breach
|
|
try:
|
|
per_commitment_secret = chan.revocation_store.retrieve_secret(RevocationStore.START_INDEX - ctn)
|
|
except UnableToDeriveSecret:
|
|
return
|
|
their_pcp = ecc.ECPrivkey(per_commitment_secret).get_public_key_bytes(compressed=True)
|
|
is_revocation = True
|
|
#chan.logger.debug(f'(lnsweep) tx for revoked: {list(txs.keys())}')
|
|
elif chan.get_data_loss_protect_remote_pcp(ctn):
|
|
their_pcp = chan.get_data_loss_protect_remote_pcp(ctn)
|
|
is_revocation = False
|
|
else:
|
|
return
|
|
return ctn, their_pcp, is_revocation, per_commitment_secret
|
|
|
|
|
|
def extract_funding_pubkeys_from_ctx(txin: TxInput) -> Tuple[bytes, bytes]:
|
|
"""Extract the two funding pubkeys from the published commitment transaction.
|
|
|
|
We expect to see a witness script of: OP_2 pk1 pk2 OP_2 OP_CHECKMULTISIG"""
|
|
elements = txin.witness_elements()
|
|
witness_script = elements[-1]
|
|
assert match_script_against_template(witness_script, SCRIPT_TEMPLATE_FUNDING)
|
|
parsed_script = [x for x in script_GetOp(witness_script)]
|
|
pubkey1 = parsed_script[1][1]
|
|
pubkey2 = parsed_script[2][1]
|
|
return (pubkey1, pubkey2)
|
|
|
|
|
|
def tx_their_ctx_to_remote_backup(
|
|
*, chan: 'ChannelBackup',
|
|
ctx: Transaction,
|
|
sweep_address: str) -> Optional[Dict[str, SweepInfo]]:
|
|
txs = {} # type: Dict[str, SweepInfo]
|
|
"""If we only have a backup, and the remote force-closed with their ctx,
|
|
and anchors are enabled, we need to sweep to_remote."""
|
|
|
|
if ctx_has_anchors(ctx):
|
|
# for anchors we need to sweep to_remote
|
|
funding_pubkeys = extract_funding_pubkeys_from_ctx(ctx.inputs()[0])
|
|
_logger.debug(f'checking their ctx for funding pubkeys: {[pk.hex() for pk in funding_pubkeys]}')
|
|
# check which of the pubkey was ours
|
|
for pubkey in funding_pubkeys:
|
|
candidate_basepoint = derive_payment_basepoint(chan.lnworker.static_payment_key.privkey, funding_pubkey=pubkey)
|
|
candidate_to_remote_address = make_commitment_output_to_remote_address(candidate_basepoint.pubkey, has_anchors=True)
|
|
if ctx.get_output_idxs_from_address(candidate_to_remote_address):
|
|
our_payment_pubkey = candidate_basepoint
|
|
to_remote_address = candidate_to_remote_address
|
|
_logger.debug(f'found funding pubkey')
|
|
break
|
|
else:
|
|
return
|
|
else:
|
|
# we are dealing with static_remotekey which is locked to a wallet address
|
|
return {}
|
|
|
|
# to_remote
|
|
csv_delay = 1
|
|
our_payment_privkey = ecc.ECPrivkey(our_payment_pubkey.privkey)
|
|
output_idxs = ctx.get_output_idxs_from_address(to_remote_address)
|
|
if output_idxs:
|
|
output_idx = output_idxs.pop()
|
|
prevout = ctx.txid() + ':%d' % output_idx
|
|
sweep_tx = lambda: tx_their_ctx_to_remote(
|
|
sweep_address=sweep_address,
|
|
ctx=ctx,
|
|
output_idx=output_idx,
|
|
our_payment_privkey=our_payment_privkey,
|
|
config=chan.lnworker.config,
|
|
has_anchors=True
|
|
)
|
|
txs[prevout] = SweepInfo(
|
|
name='their_ctx_to_remote_backup',
|
|
csv_delay=csv_delay,
|
|
cltv_abs=0,
|
|
gen_tx=sweep_tx)
|
|
return txs
|
|
|
|
|
|
|
|
|
|
def txs_their_ctx(
|
|
*, chan: 'Channel',
|
|
ctx: Transaction,
|
|
sweep_address: str) -> Optional[Dict[str, SweepInfo]]:
|
|
"""Handle the case when the remote force-closes with their ctx.
|
|
Sweep outputs that do not have a CSV delay ('to_remote' and first-stage HTLCs).
|
|
Outputs with CSV delay ('to_local' and second-stage HTLCs) are redeemed by LNWatcher.
|
|
|
|
We sweep:
|
|
to_local: if revoked
|
|
to_remote: CSV delay with anchors, otherwise sweeping not needed
|
|
htlc success: CSV delay with anchors, no delay otherwise, or revoked
|
|
htlc timeout: CSV delay with anchors, CLTV locktime, or revoked
|
|
second-stage htlc transactions: CSV delay
|
|
|
|
Outputs with CSV/CLTV are redeemed by LNWatcher.
|
|
"""
|
|
txs = {} # type: Dict[str, SweepInfo]
|
|
our_conf, their_conf = get_ordered_channel_configs(chan=chan, for_us=True)
|
|
x = extract_ctx_secrets(chan, ctx)
|
|
if not x:
|
|
return
|
|
ctn, their_pcp, is_revocation, per_commitment_secret = x
|
|
# to_local
|
|
our_revocation_pubkey = derive_blinded_pubkey(our_conf.revocation_basepoint.pubkey, their_pcp)
|
|
their_delayed_pubkey = derive_pubkey(their_conf.delayed_basepoint.pubkey, their_pcp)
|
|
witness_script = make_commitment_output_to_local_witness_script(
|
|
our_revocation_pubkey, our_conf.to_self_delay, their_delayed_pubkey)
|
|
to_local_address = redeem_script_to_address('p2wsh', witness_script)
|
|
to_remote_address = None
|
|
# test if this is their ctx
|
|
found_to_local = bool(ctx.get_output_idxs_from_address(to_local_address))
|
|
if not chan.is_backup():
|
|
assert chan.is_static_remotekey_enabled()
|
|
our_payment_pubkey = our_conf.payment_basepoint.pubkey
|
|
to_remote_address = make_commitment_output_to_remote_address(our_payment_pubkey, has_anchors=chan.has_anchors())
|
|
found_to_remote = bool(ctx.get_output_idxs_from_address(to_remote_address))
|
|
else:
|
|
found_to_remote = False
|
|
if not found_to_local and not found_to_remote:
|
|
return
|
|
chan.logger.debug(f'(lnsweep) found their ctx: {to_local_address} {to_remote_address}')
|
|
|
|
# to_local is handled by lnwatcher
|
|
if is_revocation:
|
|
our_revocation_privkey = derive_blinded_privkey(our_conf.revocation_basepoint.privkey, per_commitment_secret)
|
|
gen_tx = tx_their_ctx_justice(chan, ctx, per_commitment_secret, sweep_address)
|
|
if gen_tx:
|
|
tx = gen_tx()
|
|
txs[tx.inputs()[0].prevout.to_str()] = SweepInfo(
|
|
name='to_local_for_revoked_ctx',
|
|
csv_delay=0,
|
|
cltv_abs=0,
|
|
gen_tx=gen_tx)
|
|
|
|
|
|
# to_remote
|
|
if chan.has_anchors():
|
|
csv_delay = 1
|
|
sweep_to_remote = True
|
|
our_payment_privkey = ecc.ECPrivkey(our_conf.payment_basepoint.privkey)
|
|
else:
|
|
assert chan.is_static_remotekey_enabled()
|
|
csv_delay = 0
|
|
sweep_to_remote = False
|
|
our_payment_privkey = None
|
|
|
|
if sweep_to_remote:
|
|
assert our_payment_pubkey == our_payment_privkey.get_public_key_bytes(compressed=True)
|
|
output_idxs = ctx.get_output_idxs_from_address(to_remote_address)
|
|
if output_idxs:
|
|
output_idx = output_idxs.pop()
|
|
prevout = ctx.txid() + ':%d' % output_idx
|
|
sweep_tx = lambda: tx_their_ctx_to_remote(
|
|
sweep_address=sweep_address,
|
|
ctx=ctx,
|
|
output_idx=output_idx,
|
|
our_payment_privkey=our_payment_privkey,
|
|
config=chan.lnworker.config,
|
|
has_anchors=chan.has_anchors()
|
|
)
|
|
txs[prevout] = SweepInfo(
|
|
name='their_ctx_to_remote',
|
|
csv_delay=csv_delay,
|
|
cltv_abs=0,
|
|
gen_tx=sweep_tx)
|
|
|
|
# HTLCs
|
|
our_htlc_privkey = derive_privkey(secret=int.from_bytes(our_conf.htlc_basepoint.privkey, 'big'), per_commitment_point=their_pcp)
|
|
our_htlc_privkey = ecc.ECPrivkey.from_secret_scalar(our_htlc_privkey)
|
|
their_htlc_pubkey = derive_pubkey(their_conf.htlc_basepoint.pubkey, their_pcp)
|
|
def tx_htlc(
|
|
*, htlc: 'UpdateAddHtlc',
|
|
is_received_htlc: bool,
|
|
ctx_output_idx: int,
|
|
preimage: Optional[bytes]) -> None:
|
|
htlc_output_witness_script = make_htlc_output_witness_script(
|
|
is_received_htlc=is_received_htlc,
|
|
remote_revocation_pubkey=our_revocation_pubkey,
|
|
remote_htlc_pubkey=our_htlc_privkey.get_public_key_bytes(compressed=True),
|
|
local_htlc_pubkey=their_htlc_pubkey,
|
|
payment_hash=htlc.payment_hash,
|
|
cltv_abs=htlc.cltv_abs,
|
|
has_anchors=chan.has_anchors())
|
|
|
|
cltv_abs = htlc.cltv_abs if is_received_htlc and not is_revocation else 0
|
|
csv_delay = 1 if chan.has_anchors() else 0
|
|
prevout = ctx.txid() + ':%d'%ctx_output_idx
|
|
sweep_tx = lambda: tx_their_ctx_htlc(
|
|
ctx=ctx,
|
|
witness_script=htlc_output_witness_script,
|
|
sweep_address=sweep_address,
|
|
preimage=preimage,
|
|
output_idx=ctx_output_idx,
|
|
privkey=our_revocation_privkey if is_revocation else our_htlc_privkey.get_secret_bytes(),
|
|
is_revocation=is_revocation,
|
|
cltv_abs=cltv_abs,
|
|
config=chan.lnworker.config,
|
|
has_anchors=chan.has_anchors(),
|
|
)
|
|
txs[prevout] = SweepInfo(
|
|
name=f'their_ctx_htlc_{ctx_output_idx}{"_for_revoked_ctx" if is_revocation else ""}',
|
|
csv_delay=csv_delay,
|
|
cltv_abs=cltv_abs,
|
|
gen_tx=sweep_tx)
|
|
# received HTLCs, in their ctx --> "timeout"
|
|
# offered HTLCs, in their ctx --> "success"
|
|
htlc_to_ctx_output_idx_map = map_htlcs_to_ctx_output_idxs(
|
|
chan=chan,
|
|
ctx=ctx,
|
|
pcp=their_pcp,
|
|
subject=REMOTE,
|
|
ctn=ctn)
|
|
for (direction, htlc), (ctx_output_idx, htlc_relative_idx) in htlc_to_ctx_output_idx_map.items():
|
|
is_received_htlc = direction == RECEIVED
|
|
if not is_received_htlc and not is_revocation:
|
|
if not chan.lnworker.is_accepted_mpp(htlc.payment_hash):
|
|
# do not redeem this, it might publish the preimage of an incomplete MPP
|
|
continue
|
|
preimage = chan.lnworker.get_preimage(htlc.payment_hash)
|
|
if not preimage:
|
|
# we might not have the preimage if this is a hold invoice
|
|
continue
|
|
else:
|
|
preimage = None
|
|
tx_htlc(
|
|
htlc=htlc,
|
|
is_received_htlc=is_received_htlc,
|
|
ctx_output_idx=ctx_output_idx,
|
|
preimage=preimage)
|
|
return txs
|
|
|
|
|
|
def tx_our_ctx_htlctx(
|
|
chan: 'Channel',
|
|
our_pcp: bytes,
|
|
ctx: Transaction,
|
|
htlc: 'UpdateAddHtlc',
|
|
local_htlc_privkey: bytes,
|
|
preimage: Optional[bytes],
|
|
htlc_direction: Direction,
|
|
htlc_relative_idx: int,
|
|
ctx_output_idx: int) -> Tuple[bytes, Transaction]:
|
|
assert (htlc_direction == RECEIVED) == bool(preimage), 'preimage is required iff htlc is received'
|
|
preimage = preimage or b''
|
|
ctn = extract_ctn_from_tx_and_chan(ctx, chan)
|
|
witness_script_out, maybe_zero_fee_htlc_tx = make_htlc_tx_with_open_channel(
|
|
chan=chan,
|
|
pcp=our_pcp,
|
|
subject=LOCAL,
|
|
ctn=ctn,
|
|
htlc_direction=htlc_direction,
|
|
commit=ctx,
|
|
htlc=htlc,
|
|
ctx_output_idx=ctx_output_idx,
|
|
name=f'our_ctx_{ctx_output_idx}_htlc_tx_{htlc.payment_hash.hex()}')
|
|
|
|
# we need to attach inputs that pay for the transaction fee
|
|
if chan.has_anchors():
|
|
wallet = chan.lnworker.wallet
|
|
coins = wallet.get_spendable_coins(None)
|
|
|
|
def fee_estimator(size):
|
|
if htlc_direction == SENT:
|
|
# we deal with an offered HTLC and therefore with a timeout transaction
|
|
# in this case it is not time critical for us to sweep unless we
|
|
# become a forwarding node
|
|
fee_per_kb = wallet.config.eta_target_to_fee(HTLC_TRANSACTION_SWEEP_TARGET)
|
|
else:
|
|
# in the case of a received HTLC, if we have the hash preimage,
|
|
# we should sweep before the timelock expires
|
|
expiry_height = htlc.cltv_abs
|
|
current_height = wallet.network.blockchain().height()
|
|
deadline_blocks = expiry_height - current_height
|
|
# target block inclusion with a safety buffer
|
|
target = int(deadline_blocks / HTLC_TRANSACTION_DEADLINE_FRACTION)
|
|
fee_per_kb = wallet.config.eta_target_to_fee(target)
|
|
if not fee_per_kb: # testnet and other cases
|
|
fee_per_kb = wallet.config.fee_per_kb()
|
|
fee = wallet.config.estimate_fee_for_feerate(fee_per_kb=fee_per_kb, size=size)
|
|
# we only sweep if it is makes sense economically
|
|
if fee > htlc.amount_msat // 1000:
|
|
raise UneconomicFee
|
|
return fee
|
|
|
|
coin_chooser = coinchooser.get_coin_chooser(wallet.config)
|
|
change_address = wallet.get_single_change_address_for_new_transaction()
|
|
funded_htlc_tx = coin_chooser.make_tx(
|
|
coins=coins,
|
|
inputs=maybe_zero_fee_htlc_tx.inputs(),
|
|
outputs=maybe_zero_fee_htlc_tx.outputs(),
|
|
change_addrs=[change_address],
|
|
fee_estimator_vb=fee_estimator,
|
|
dust_threshold=wallet.dust_threshold())
|
|
|
|
# place htlc input/output at corresponding indices (due to sighash single)
|
|
htlc_outpoint = TxOutpoint(txid=bfh(ctx.txid()), out_idx=ctx_output_idx)
|
|
htlc_input_idx = funded_htlc_tx.get_input_idx_that_spent_prevout(htlc_outpoint)
|
|
|
|
htlc_out_address = maybe_zero_fee_htlc_tx.outputs()[HTLCTX_INPUT_OUTPUT_INDEX].address
|
|
htlc_output_idx = funded_htlc_tx.get_output_idxs_from_address(htlc_out_address).pop()
|
|
inputs = funded_htlc_tx.inputs()
|
|
outputs = funded_htlc_tx.outputs()
|
|
if htlc_input_idx != HTLCTX_INPUT_OUTPUT_INDEX:
|
|
htlc_txin = inputs.pop(htlc_input_idx)
|
|
inputs.insert(HTLCTX_INPUT_OUTPUT_INDEX, htlc_txin)
|
|
if htlc_output_idx != HTLCTX_INPUT_OUTPUT_INDEX:
|
|
htlc_txout = outputs.pop(htlc_output_idx)
|
|
outputs.insert(HTLCTX_INPUT_OUTPUT_INDEX, htlc_txout)
|
|
final_htlc_tx = PartialTransaction.from_io(
|
|
inputs,
|
|
outputs,
|
|
locktime=maybe_zero_fee_htlc_tx.locktime,
|
|
version=maybe_zero_fee_htlc_tx.version,
|
|
BIP69_sort=False
|
|
)
|
|
|
|
for fee_input_idx in range(1, len(funded_htlc_tx.inputs())):
|
|
txin = final_htlc_tx.inputs()[fee_input_idx]
|
|
pubkey = wallet.get_public_key(txin.address)
|
|
index = wallet.get_address_index(txin.address)
|
|
privkey, _ = wallet.keystore.get_private_key(index, wallet.get_unlocked_password())
|
|
desc = descriptor.get_singlesig_descriptor_from_legacy_leaf(pubkey=pubkey, script_type='p2wpkh')
|
|
txin.script_descriptor = desc
|
|
fee_input_sig = final_htlc_tx.sign_txin(fee_input_idx, privkey)
|
|
final_htlc_tx.add_signature_to_txin(txin_idx=fee_input_idx, signing_pubkey=bfh(pubkey), sig=fee_input_sig)
|
|
else:
|
|
final_htlc_tx = maybe_zero_fee_htlc_tx
|
|
|
|
# sign HTLC output
|
|
remote_htlc_sig = chan.get_remote_htlc_sig_for_htlc(htlc_relative_idx=htlc_relative_idx)
|
|
local_htlc_sig = final_htlc_tx.sign_txin(HTLCTX_INPUT_OUTPUT_INDEX, local_htlc_privkey)
|
|
txin = final_htlc_tx.inputs()[HTLCTX_INPUT_OUTPUT_INDEX]
|
|
witness_script_in = txin.witness_script
|
|
assert witness_script_in
|
|
txin.witness = make_htlc_tx_witness(remote_htlc_sig, local_htlc_sig, preimage, witness_script_in)
|
|
return witness_script_out, final_htlc_tx
|
|
|
|
|
|
def tx_their_ctx_htlc(
|
|
ctx: Transaction, witness_script: bytes, sweep_address: str,
|
|
preimage: Optional[bytes], output_idx: int,
|
|
privkey: bytes, is_revocation: bool,
|
|
cltv_abs: int,
|
|
config: SimpleConfig,
|
|
has_anchors: bool,
|
|
) -> Optional[PartialTransaction]:
|
|
"""Deals with normal (non-CSV timelocked) HTLC output sweeps."""
|
|
assert type(cltv_abs) is int
|
|
preimage = preimage or b'' # preimage is required iff (not is_revocation and htlc is offered)
|
|
val = ctx.outputs()[output_idx].value
|
|
prevout = TxOutpoint(txid=bfh(ctx.txid()), out_idx=output_idx)
|
|
txin = PartialTxInput(prevout=prevout)
|
|
txin._trusted_value_sats = val
|
|
txin.witness_script = witness_script
|
|
txin.script_sig = b''
|
|
txin.nsequence = 1 if has_anchors else 0xffffffff - 2
|
|
sweep_inputs = [txin]
|
|
tx_size_bytes = 200 # TODO (depends on offered/received and is_revocation)
|
|
fee = config.estimate_fee(tx_size_bytes, allow_fallback_to_static_rates=True)
|
|
outvalue = val - fee
|
|
if outvalue <= dust_threshold(): return None
|
|
sweep_outputs = [PartialTxOutput.from_address_and_value(sweep_address, outvalue)]
|
|
tx = PartialTransaction.from_io(sweep_inputs, sweep_outputs, version=2, locktime=cltv_abs)
|
|
sig = tx.sign_txin(0, privkey)
|
|
if not is_revocation:
|
|
witness = construct_witness([sig, preimage, witness_script])
|
|
else:
|
|
revocation_pubkey = privkey_to_pubkey(privkey)
|
|
witness = construct_witness([sig, revocation_pubkey, witness_script])
|
|
tx.inputs()[0].witness = witness
|
|
assert tx.is_complete()
|
|
return tx
|
|
|
|
|
|
|
|
def tx_their_ctx_to_remote(
|
|
sweep_address: str, ctx: Transaction, output_idx: int,
|
|
our_payment_privkey: ecc.ECPrivkey,
|
|
config: SimpleConfig,
|
|
has_anchors: bool,
|
|
) -> Optional[PartialTransaction]:
|
|
assert has_anchors is True
|
|
our_payment_pubkey = our_payment_privkey.get_public_key_bytes(compressed=True)
|
|
val = ctx.outputs()[output_idx].value
|
|
prevout = TxOutpoint(txid=bfh(ctx.txid()), out_idx=output_idx)
|
|
txin = PartialTxInput(prevout=prevout)
|
|
txin._trusted_value_sats = val
|
|
desc = descriptor.get_singlesig_descriptor_from_legacy_leaf(pubkey=our_payment_pubkey.hex(), script_type='p2wpkh')
|
|
txin.script_descriptor = desc
|
|
txin.num_sig = 1
|
|
txin.script_sig = b''
|
|
txin.witness_script = make_commitment_output_to_remote_witness_script(our_payment_pubkey)
|
|
txin.nsequence = 1
|
|
tx_size_bytes = 196 # approx size of p2wsh->p2wpkh
|
|
sweep_inputs = [txin]
|
|
fee = config.estimate_fee(tx_size_bytes, allow_fallback_to_static_rates=True)
|
|
outvalue = val - fee
|
|
if outvalue <= dust_threshold(): return None
|
|
sweep_outputs = [PartialTxOutput.from_address_and_value(sweep_address, outvalue)]
|
|
sweep_tx = PartialTransaction.from_io(sweep_inputs, sweep_outputs)
|
|
|
|
sig = sweep_tx.sign_txin(0, our_payment_privkey.get_secret_bytes())
|
|
witness = construct_witness([sig, sweep_tx.inputs()[0].witness_script])
|
|
sweep_tx.inputs()[0].witness = witness
|
|
|
|
if not sweep_tx.is_complete():
|
|
raise Exception('channel close sweep tx is not complete')
|
|
return sweep_tx
|
|
|
|
|
|
|
|
|
|
|
|
def tx_ctx_to_local(
|
|
*, sweep_address: str, ctx: Transaction, output_idx: int, witness_script: bytes,
|
|
privkey: bytes, is_revocation: bool, config: SimpleConfig,
|
|
to_self_delay: int = None) -> Optional[PartialTransaction]:
|
|
"""Create a txn that sweeps the 'to_local' output of a commitment
|
|
transaction into our wallet.
|
|
|
|
privkey: either revocation_privkey or localdelayed_privkey
|
|
is_revocation: tells us which ^
|
|
"""
|
|
val = ctx.outputs()[output_idx].value
|
|
prevout = TxOutpoint(txid=bfh(ctx.txid()), out_idx=output_idx)
|
|
txin = PartialTxInput(prevout=prevout)
|
|
txin._trusted_value_sats = val
|
|
txin.script_sig = b''
|
|
txin.witness_script = witness_script
|
|
txin.nsequence = 0xffffffff - 2
|
|
sweep_inputs = [txin]
|
|
if not is_revocation:
|
|
assert isinstance(to_self_delay, int)
|
|
sweep_inputs[0].nsequence = to_self_delay
|
|
tx_size_bytes = 121 # approx size of to_local -> p2wpkh
|
|
fee = config.estimate_fee(tx_size_bytes, allow_fallback_to_static_rates=True)
|
|
outvalue = val - fee
|
|
if outvalue <= dust_threshold():
|
|
return None
|
|
sweep_outputs = [PartialTxOutput.from_address_and_value(sweep_address, outvalue)]
|
|
sweep_tx = PartialTransaction.from_io(sweep_inputs, sweep_outputs, version=2)
|
|
sig = sweep_tx.sign_txin(0, privkey)
|
|
witness = construct_witness([sig, int(is_revocation), witness_script])
|
|
sweep_tx.inputs()[0].witness = witness
|
|
return sweep_tx
|
|
|
|
|
|
|
|
def tx_sweep_htlctx_output(
|
|
*, htlc_tx: Transaction, output_idx: int, htlctx_witness_script: bytes, sweep_address: str,
|
|
privkey: bytes, is_revocation: bool, to_self_delay: int = None,
|
|
config: SimpleConfig) -> Optional[PartialTransaction]:
|
|
"""Create a txn that sweeps the output of a first stage htlc tx
|
|
(i.e. sweeps from an HTLC-Timeout or an HTLC-Success tx).
|
|
"""
|
|
# note: this is the same as sweeping the to_local output of the ctx,
|
|
# as these are the same script (address-reuse).
|
|
return tx_ctx_to_local(
|
|
sweep_address=sweep_address,
|
|
ctx=htlc_tx,
|
|
output_idx=output_idx,
|
|
witness_script=htlctx_witness_script,
|
|
privkey=privkey,
|
|
is_revocation=is_revocation,
|
|
to_self_delay=to_self_delay,
|
|
config=config,
|
|
)
|