AaronFiore/electrum
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lnworker.force_close_channel: set chan state before broadcast

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It is not safe to keep using the channel after we attempted to broadcast a force-close,
even if the broadcast errored: the server cannot be trusted wrt to errors.

Note that if there is a network-error, due to the state-transition, the GUI won't offer
the force-close option to the user again. However, LNWallet will periodically rebroadcast
the tx automatically (in on_channel_update); and we also save the tx as local into the
wallet.
This commit is contained in:
SomberNight
2022-02-18 17:20:30 +01:00
parent 88121d7924
commit 96fcf68d84
1 changed files with 24 additions and 9 deletions
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33
electrum/lnworker.py
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@@ -41,7 +41,7 @@ from .util import bh2u, bfh, InvoiceError, resolve_dns_srv, is_ip_address, log_e
from .crypto import chacha20_encrypt, chacha20_decrypt
from .util import ignore_exceptions, make_aiohttp_session
from .util import timestamp_to_datetime, random_shuffled_copy
from .util import MyEncoder, is_private_netaddress
from .util import MyEncoder, is_private_netaddress, UnrelatedTransactionException
from .logging import Logger
from .lntransport import LNTransport, LNResponderTransport, LNTransportBase
from .lnpeer import Peer, LN_P2P_NETWORK_TIMEOUT
@@ -2075,19 +2075,34 @@ class LNWallet(LNWorker):
peer = self._peers[chan.node_id]
return await peer.close_channel(chan_id)
async def force_close_channel(self, chan_id):
# returns txid or raises
def _force_close_channel(self, chan_id: bytes) -> Transaction:
chan = self._channels[chan_id]
tx = chan.force_close_tx()
await self.network.broadcast_transaction(tx)
# We set the channel state to make sure we won't sign new commitment txs.
# We expect the caller to try to broadcast this tx, after which it is
# not safe to keep using the channel even if the broadcast errors (server could be lying).
# Until the tx is seen in the mempool, there will be automatic rebroadcasts.
chan.set_state(ChannelState.FORCE_CLOSING)
# Add local tx to wallet to also allow manual rebroadcasts.
try:
self.wallet.add_transaction(tx)
except UnrelatedTransactionException:
pass # this can happen if (~all the balance goes to REMOTE)
return tx
async def force_close_channel(self, chan_id: bytes) -> str:
"""Force-close the channel. Network-related exceptions are propagated to the caller.
(automatic rebroadcasts will be scheduled)
"""
tx = self._force_close_channel(chan_id)
await self.network.broadcast_transaction(tx)
return tx.txid()
async def try_force_closing(self, chan_id):
# fails silently but sets the state, so that we will retry later
chan = self._channels[chan_id]
tx = chan.force_close_tx()
chan.set_state(ChannelState.FORCE_CLOSING)
async def try_force_closing(self, chan_id: bytes) -> None:
"""Force-close the channel. Network-related exceptions are suppressed.
(automatic rebroadcasts will be scheduled)
"""
tx = self._force_close_channel(chan_id)
await self.network.try_broadcasting(tx, 'force-close')
def remove_channel(self, chan_id):