}
}
-/// An error enum representing a failure to persist a channel monitor update.
-#[derive(Clone, Copy, Debug, PartialEq)]
-pub enum ChannelMonitorUpdateErr {
- /// Used to indicate a temporary failure (eg connection to a watchtower or remote backup of
- /// our state failed, but is expected to succeed at some point in the future).
- ///
- /// Such a failure will "freeze" a channel, preventing us from revoking old states or
- /// submitting new commitment transactions to the counterparty. Once the update(s) which failed
- /// have been successfully applied, ChannelManager::channel_monitor_updated can be used to
- /// restore the channel to an operational state.
- ///
- /// Note that a given ChannelManager will *never* re-generate a given ChannelMonitorUpdate. If
- /// you return a TemporaryFailure you must ensure that it is written to disk safely before
- /// writing out the latest ChannelManager state.
- ///
- /// Even when a channel has been "frozen" updates to the ChannelMonitor can continue to occur
- /// (eg if an inbound HTLC which we forwarded was claimed upstream resulting in us attempting
- /// to claim it on this channel) and those updates must be applied wherever they can be. At
- /// least one such updated ChannelMonitor must be persisted otherwise PermanentFailure should
- /// be returned to get things on-chain ASAP using only the in-memory copy. Obviously updates to
- /// the channel which would invalidate previous ChannelMonitors are not made when a channel has
- /// been "frozen".
- ///
- /// Note that even if updates made after TemporaryFailure succeed you must still call
- /// channel_monitor_updated to ensure you have the latest monitor and re-enable normal channel
- /// operation.
- ///
- /// Note that the update being processed here will not be replayed for you when you call
- /// ChannelManager::channel_monitor_updated, so you must store the update itself along
- /// with the persisted ChannelMonitor on your own local disk prior to returning a
- /// TemporaryFailure. You may, of course, employ a journaling approach, storing only the
- /// ChannelMonitorUpdate on disk without updating the monitor itself, replaying the journal at
- /// reload-time.
- ///
- /// For deployments where a copy of ChannelMonitors and other local state are backed up in a
- /// remote location (with local copies persisted immediately), it is anticipated that all
- /// updates will return TemporaryFailure until the remote copies could be updated.
- TemporaryFailure,
- /// Used to indicate no further channel monitor updates will be allowed (eg we've moved on to a
- /// different watchtower and cannot update with all watchtowers that were previously informed
- /// of this channel).
- ///
- /// At reception of this error, ChannelManager will force-close the channel and return at
- /// least a final ChannelMonitorUpdate::ChannelForceClosed which must be delivered to at
- /// least one ChannelMonitor copy. Revocation secret MUST NOT be released and offchain channel
- /// update must be rejected.
- ///
- /// This failure may also signal a failure to update the local persisted copy of one of
- /// the channel monitor instance.
- ///
- /// Note that even when you fail a holder commitment transaction update, you must store the
- /// update to ensure you can claim from it in case of a duplicate copy of this ChannelMonitor
- /// broadcasts it (e.g distributed channel-monitor deployment)
- ///
- /// In case of distributed watchtowers deployment, the new version must be written to disk, as
- /// state may have been stored but rejected due to a block forcing a commitment broadcast. This
- /// storage is used to claim outputs of rejected state confirmed onchain by another watchtower,
- /// lagging behind on block processing.
- PermanentFailure,
-}
-
/// General Err type for ChannelMonitor actions. Generally, this implies that the data provided is
/// inconsistent with the ChannelMonitor being called. eg for ChannelMonitor::update_monitor this
/// means you tried to update a monitor for a different channel or the ChannelMonitorUpdate was
/// A monitor event that the Channel's commitment transaction was confirmed.
CommitmentTxConfirmed(OutPoint),
+
+ /// Indicates a [`ChannelMonitor`] update has completed. See
+ /// [`ChannelMonitorUpdateErr::TemporaryFailure`] for more information on how this is used.
+ ///
+ /// [`ChannelMonitorUpdateErr::TemporaryFailure`]: super::ChannelMonitorUpdateErr::TemporaryFailure
+ UpdateCompleted {
+ /// The funding outpoint of the [`ChannelMonitor`] that was updated
+ funding_txo: OutPoint,
+ /// The Update ID from [`ChannelMonitorUpdate::update_id`] which was applied or
+ /// [`ChannelMonitor::get_latest_update_id`].
+ ///
+ /// Note that this should only be set to a given update's ID if all previous updates for the
+ /// same [`ChannelMonitor`] have been applied and persisted.
+ monitor_update_id: u64,
+ },
+
+ /// Indicates a [`ChannelMonitor`] update has failed. See
+ /// [`ChannelMonitorUpdateErr::PermanentFailure`] for more information on how this is used.
+ ///
+ /// [`ChannelMonitorUpdateErr::PermanentFailure`]: super::ChannelMonitorUpdateErr::PermanentFailure
+ UpdateFailed(OutPoint),
}
+impl_writeable_tlv_based_enum_upgradable!(MonitorEvent,
+ // Note that UpdateCompleted and UpdateFailed are currently never serialized to disk as they are
+ // generated only in ChainMonitor
+ (0, UpdateCompleted) => {
+ (0, funding_txo, required),
+ (2, monitor_update_id, required),
+ },
+;
+ (2, HTLCEvent),
+ (4, CommitmentTxConfirmed),
+ (6, UpdateFailed),
+);
/// Simple structure sent back by `chain::Watch` when an HTLC from a forward channel is detected on
/// chain. Used to update the corresponding HTLC in the backward channel. Failing to pass the
payment_preimages: HashMap<PaymentHash, PaymentPreimage>,
+ // Note that `MonitorEvent`s MUST NOT be generated during update processing, only generated
+ // during chain data processing. This prevents a race in `ChainMonitor::update_channel` (and
+ // presumably user implementations thereof as well) where we update the in-memory channel
+ // object, then before the persistence finishes (as it's all under a read-lock), we return
+ // pending events to the user or to the relevant `ChannelManager`. Then, on reload, we'll have
+ // the pre-event state here, but have processed the event in the `ChannelManager`.
+ // Note that because the `event_lock` in `ChainMonitor` is only taken in
+ // block/transaction-connected events and *not* during block/transaction-disconnected events,
+ // we further MUST NOT generate events during block/transaction-disconnection.
pending_monitor_events: Vec<MonitorEvent>,
+
pending_events: Vec<Event>,
// Used to track on-chain events (i.e., transactions part of channels confirmed on chain) on
writer.write_all(&payment_preimage.0[..])?;
}
- writer.write_all(&byte_utils::be64_to_array(self.pending_monitor_events.len() as u64))?;
+ writer.write_all(&(self.pending_monitor_events.iter().filter(|ev| match ev {
+ MonitorEvent::HTLCEvent(_) => true,
+ MonitorEvent::CommitmentTxConfirmed(_) => true,
+ _ => false,
+ }).count() as u64).to_be_bytes())?;
for event in self.pending_monitor_events.iter() {
match event {
MonitorEvent::HTLCEvent(upd) => {
0u8.write(writer)?;
upd.write(writer)?;
},
- MonitorEvent::CommitmentTxConfirmed(_) => 1u8.write(writer)?
+ MonitorEvent::CommitmentTxConfirmed(_) => 1u8.write(writer)?,
+ _ => {}, // Covered in the TLV writes below
}
}
write_tlv_fields!(writer, {
(1, self.funding_spend_confirmed, option),
(3, self.htlcs_resolved_on_chain, vec_type),
+ (5, self.pending_monitor_events, vec_type),
});
Ok(())
res
}
+
+ /// Gets the set of outbound HTLCs which are pending resolution in this channel.
+ /// This is used to reconstruct pending outbound payments on restart in the ChannelManager.
+ pub(crate) fn get_pending_outbound_htlcs(&self) -> HashMap<HTLCSource, HTLCOutputInCommitment> {
+ let mut res = HashMap::new();
+ let us = self.inner.lock().unwrap();
+
+ macro_rules! walk_htlcs {
+ ($holder_commitment: expr, $htlc_iter: expr) => {
+ for (htlc, source) in $htlc_iter {
+ if us.htlcs_resolved_on_chain.iter().any(|v| Some(v.input_idx) == htlc.transaction_output_index) {
+ // We should assert that funding_spend_confirmed is_some() here, but we
+ // have some unit tests which violate HTLC transaction CSVs entirely and
+ // would fail.
+ // TODO: Once tests all connect transactions at consensus-valid times, we
+ // should assert here like we do in `get_claimable_balances`.
+ } else if htlc.offered == $holder_commitment {
+ // If the payment was outbound, check if there's an HTLCUpdate
+ // indicating we have spent this HTLC with a timeout, claiming it back
+ // and awaiting confirmations on it.
+ let htlc_update_confd = us.onchain_events_awaiting_threshold_conf.iter().any(|event| {
+ if let OnchainEvent::HTLCUpdate { input_idx: Some(input_idx), .. } = event.event {
+ // If the HTLC was timed out, we wait for ANTI_REORG_DELAY blocks
+ // before considering it "no longer pending" - this matches when we
+ // provide the ChannelManager an HTLC failure event.
+ Some(input_idx) == htlc.transaction_output_index &&
+ us.best_block.height() >= event.height + ANTI_REORG_DELAY - 1
+ } else if let OnchainEvent::HTLCSpendConfirmation { input_idx, .. } = event.event {
+ // If the HTLC was fulfilled with a preimage, we consider the HTLC
+ // immediately non-pending, matching when we provide ChannelManager
+ // the preimage.
+ Some(input_idx) == htlc.transaction_output_index
+ } else { false }
+ });
+ if !htlc_update_confd {
+ res.insert(source.clone(), htlc.clone());
+ }
+ }
+ }
+ }
+ }
+
+ // We're only concerned with the confirmation count of HTLC transactions, and don't
+ // actually care how many confirmations a commitment transaction may or may not have. Thus,
+ // we look for either a FundingSpendConfirmation event or a funding_spend_confirmed.
+ let confirmed_txid = us.funding_spend_confirmed.or_else(|| {
+ us.onchain_events_awaiting_threshold_conf.iter().find_map(|event| {
+ if let OnchainEvent::FundingSpendConfirmation { .. } = event.event {
+ Some(event.txid)
+ } else { None }
+ })
+ });
+ if let Some(txid) = confirmed_txid {
+ if Some(txid) == us.current_counterparty_commitment_txid || Some(txid) == us.prev_counterparty_commitment_txid {
+ walk_htlcs!(false, us.counterparty_claimable_outpoints.get(&txid).unwrap().iter().filter_map(|(a, b)| {
+ if let &Some(ref source) = b {
+ Some((a, &**source))
+ } else { None }
+ }));
+ } else if txid == us.current_holder_commitment_tx.txid {
+ walk_htlcs!(true, us.current_holder_commitment_tx.htlc_outputs.iter().filter_map(|(a, _, c)| {
+ if let Some(source) = c { Some((a, source)) } else { None }
+ }));
+ } else if let Some(prev_commitment) = &us.prev_holder_signed_commitment_tx {
+ if txid == prev_commitment.txid {
+ walk_htlcs!(true, prev_commitment.htlc_outputs.iter().filter_map(|(a, _, c)| {
+ if let Some(source) = c { Some((a, source)) } else { None }
+ }));
+ }
+ }
+ } else {
+ // If we have not seen a commitment transaction on-chain (ie the channel is not yet
+ // closed), just examine the available counterparty commitment transactions. See docs
+ // on `fail_unbroadcast_htlcs`, below, for justification.
+ macro_rules! walk_counterparty_commitment {
+ ($txid: expr) => {
+ if let Some(ref latest_outpoints) = us.counterparty_claimable_outpoints.get($txid) {
+ for &(ref htlc, ref source_option) in latest_outpoints.iter() {
+ if let &Some(ref source) = source_option {
+ res.insert((**source).clone(), htlc.clone());
+ }
+ }
+ }
+ }
+ }
+ if let Some(ref txid) = us.current_counterparty_commitment_txid {
+ walk_counterparty_commitment!(txid);
+ }
+ if let Some(ref txid) = us.prev_counterparty_commitment_txid {
+ walk_counterparty_commitment!(txid);
+ }
+ }
+
+ res
+ }
}
/// Compares a broadcasted commitment transaction's HTLCs with those in the latest state,
let revocation_sig_claim = (input.witness.len() == 3 && HTLCType::scriptlen_to_htlctype(input.witness[2].len()) == Some(HTLCType::OfferedHTLC) && input.witness[1].len() == 33)
|| (input.witness.len() == 3 && HTLCType::scriptlen_to_htlctype(input.witness[2].len()) == Some(HTLCType::AcceptedHTLC) && input.witness[1].len() == 33);
let accepted_preimage_claim = input.witness.len() == 5 && HTLCType::scriptlen_to_htlctype(input.witness[4].len()) == Some(HTLCType::AcceptedHTLC);
+ #[cfg(not(fuzzing))]
let accepted_timeout_claim = input.witness.len() == 3 && HTLCType::scriptlen_to_htlctype(input.witness[2].len()) == Some(HTLCType::AcceptedHTLC) && !revocation_sig_claim;
let offered_preimage_claim = input.witness.len() == 3 && HTLCType::scriptlen_to_htlctype(input.witness[2].len()) == Some(HTLCType::OfferedHTLC) && !revocation_sig_claim;
+ #[cfg(not(fuzzing))]
let offered_timeout_claim = input.witness.len() == 5 && HTLCType::scriptlen_to_htlctype(input.witness[4].len()) == Some(HTLCType::OfferedHTLC);
let mut payment_preimage = PaymentPreimage([0; 32]);
}
}
-/// `Persist` defines behavior for persisting channel monitors: this could mean
-/// writing once to disk, and/or uploading to one or more backup services.
-///
-/// Note that for every new monitor, you **must** persist the new `ChannelMonitor`
-/// to disk/backups. And, on every update, you **must** persist either the
-/// `ChannelMonitorUpdate` or the updated monitor itself. Otherwise, there is risk
-/// of situations such as revoking a transaction, then crashing before this
-/// revocation can be persisted, then unintentionally broadcasting a revoked
-/// transaction and losing money. This is a risk because previous channel states
-/// are toxic, so it's important that whatever channel state is persisted is
-/// kept up-to-date.
-pub trait Persist<ChannelSigner: Sign> {
- /// Persist a new channel's data. The data can be stored any way you want, but
- /// the identifier provided by Rust-Lightning is the channel's outpoint (and
- /// it is up to you to maintain a correct mapping between the outpoint and the
- /// stored channel data). Note that you **must** persist every new monitor to
- /// disk. See the `Persist` trait documentation for more details.
- ///
- /// See [`ChannelMonitor::write`] for writing out a `ChannelMonitor`,
- /// and [`ChannelMonitorUpdateErr`] for requirements when returning errors.
- fn persist_new_channel(&self, id: OutPoint, data: &ChannelMonitor<ChannelSigner>) -> Result<(), ChannelMonitorUpdateErr>;
-
- /// Update one channel's data. The provided `ChannelMonitor` has already
- /// applied the given update.
- ///
- /// Note that on every update, you **must** persist either the
- /// `ChannelMonitorUpdate` or the updated monitor itself to disk/backups. See
- /// the `Persist` trait documentation for more details.
- ///
- /// If an implementer chooses to persist the updates only, they need to make
- /// sure that all the updates are applied to the `ChannelMonitors` *before*
- /// the set of channel monitors is given to the `ChannelManager`
- /// deserialization routine. See [`ChannelMonitor::update_monitor`] for
- /// applying a monitor update to a monitor. If full `ChannelMonitors` are
- /// persisted, then there is no need to persist individual updates.
- ///
- /// Note that there could be a performance tradeoff between persisting complete
- /// channel monitors on every update vs. persisting only updates and applying
- /// them in batches. The size of each monitor grows `O(number of state updates)`
- /// whereas updates are small and `O(1)`.
- ///
- /// See [`ChannelMonitor::write`] for writing out a `ChannelMonitor`,
- /// [`ChannelMonitorUpdate::write`] for writing out an update, and
- /// [`ChannelMonitorUpdateErr`] for requirements when returning errors.
- fn update_persisted_channel(&self, id: OutPoint, update: &ChannelMonitorUpdate, data: &ChannelMonitor<ChannelSigner>) -> Result<(), ChannelMonitorUpdateErr>;
-}
-
impl<Signer: Sign, T: Deref, F: Deref, L: Deref> chain::Listen for (ChannelMonitor<Signer>, T, F, L)
where
T::Target: BroadcasterInterface,
}
let pending_monitor_events_len: u64 = Readable::read(reader)?;
- let mut pending_monitor_events = Vec::with_capacity(cmp::min(pending_monitor_events_len as usize, MAX_ALLOC_SIZE / (32 + 8*3)));
+ let mut pending_monitor_events = Some(
+ Vec::with_capacity(cmp::min(pending_monitor_events_len as usize, MAX_ALLOC_SIZE / (32 + 8*3))));
for _ in 0..pending_monitor_events_len {
let ev = match <u8 as Readable>::read(reader)? {
0 => MonitorEvent::HTLCEvent(Readable::read(reader)?),
1 => MonitorEvent::CommitmentTxConfirmed(funding_info.0),
_ => return Err(DecodeError::InvalidValue)
};
- pending_monitor_events.push(ev);
+ pending_monitor_events.as_mut().unwrap().push(ev);
}
let pending_events_len: u64 = Readable::read(reader)?;
read_tlv_fields!(reader, {
(1, funding_spend_confirmed, option),
(3, htlcs_resolved_on_chain, vec_type),
+ (5, pending_monitor_events, vec_type),
});
let mut secp_ctx = Secp256k1::new();
current_holder_commitment_number,
payment_preimages,
- pending_monitor_events,
+ pending_monitor_events: pending_monitor_events.unwrap(),
pending_events,
onchain_events_awaiting_threshold_conf,
projects / rust-lightning / blobdiff