1 // This file is Copyright its original authors, visible in version control
4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
7 // You may not use this file except in accordance with one or both of these
10 //! Logic to connect off-chain channel management with on-chain transaction monitoring.
12 //! [`ChainMonitor`] is an implementation of [`chain::Watch`] used both to process blocks and to
13 //! update [`ChannelMonitor`]s accordingly. If any on-chain events need further processing, it will
14 //! make those available as [`MonitorEvent`]s to be consumed.
16 //! [`ChainMonitor`] is parameterized by an optional chain source, which must implement the
17 //! [`chain::Filter`] trait. This provides a mechanism to signal new relevant outputs back to light
18 //! clients, such that transactions spending those outputs are included in block data.
20 //! [`ChainMonitor`] may be used directly to monitor channels locally or as a part of a distributed
21 //! setup to monitor channels remotely. In the latter case, a custom [`chain::Watch`] implementation
22 //! would be responsible for routing each update to a remote server and for retrieving monitor
23 //! events. The remote server would make use of [`ChainMonitor`] for block processing and for
24 //! servicing [`ChannelMonitor`] updates from the client.
26 use bitcoin::blockdata::block::{Block, BlockHeader};
27 use bitcoin::hash_types::Txid;
30 use chain::{ChannelMonitorUpdateErr, Filter, WatchedOutput};
31 use chain::chaininterface::{BroadcasterInterface, FeeEstimator};
32 use chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, Balance, MonitorEvent, TransactionOutputs, LATENCY_GRACE_PERIOD_BLOCKS};
33 use chain::transaction::{OutPoint, TransactionData};
34 use chain::keysinterface::Sign;
35 use util::atomic_counter::AtomicCounter;
36 use util::logger::Logger;
37 use util::errors::APIError;
39 use util::events::EventHandler;
40 use ln::channelmanager::ChannelDetails;
43 use sync::{RwLock, RwLockReadGuard, Mutex, MutexGuard};
45 use core::sync::atomic::{AtomicBool, AtomicUsize, Ordering};
47 #[derive(Clone, Copy, Hash, PartialEq, Eq)]
48 /// A specific update's ID stored in a `MonitorUpdateId`, separated out to make the contents
51 /// An update that was generated by the `ChannelManager` (via our `chain::Watch`
52 /// implementation). This corresponds to an actual [`ChannelMonitorUpdate::update_id`] field
53 /// and [`ChannelMonitor::get_latest_update_id`].
55 /// An update that was generated during blockchain processing. The ID here is specific to the
56 /// generating [`ChainMonitor`] and does *not* correspond to any on-disk IDs.
60 /// An opaque identifier describing a specific [`Persist`] method call.
61 #[derive(Clone, Copy, Hash, PartialEq, Eq)]
62 pub struct MonitorUpdateId {
63 contents: UpdateOrigin,
66 impl MonitorUpdateId {
67 pub(crate) fn from_monitor_update(update: &ChannelMonitorUpdate) -> Self {
68 Self { contents: UpdateOrigin::OffChain(update.update_id) }
70 pub(crate) fn from_new_monitor<ChannelSigner: Sign>(monitor: &ChannelMonitor<ChannelSigner>) -> Self {
71 Self { contents: UpdateOrigin::OffChain(monitor.get_latest_update_id()) }
75 /// `Persist` defines behavior for persisting channel monitors: this could mean
76 /// writing once to disk, and/or uploading to one or more backup services.
78 /// Each method can return three possible values:
79 /// * If persistence (including any relevant `fsync()` calls) happens immediately, the
80 /// implementation should return `Ok(())`, indicating normal channel operation should continue.
81 /// * If persistence happens asynchronously, implementations should first ensure the
82 /// [`ChannelMonitor`] or [`ChannelMonitorUpdate`] are written durably to disk, and then return
83 /// `Err(ChannelMonitorUpdateErr::TemporaryFailure)` while the update continues in the
84 /// background. Once the update completes, [`ChainMonitor::channel_monitor_updated`] should be
85 /// called with the corresponding [`MonitorUpdateId`].
87 /// Note that unlike the direct [`chain::Watch`] interface,
88 /// [`ChainMonitor::channel_monitor_updated`] must be called once for *each* update which occurs.
90 /// * If persistence fails for some reason, implementations should return
91 /// `Err(ChannelMonitorUpdateErr::PermanentFailure)`, in which case the channel will likely be
92 /// closed without broadcasting the latest state. See
93 /// [`ChannelMonitorUpdateErr::PermanentFailure`] for more details.
94 pub trait Persist<ChannelSigner: Sign> {
95 /// Persist a new channel's data. The data can be stored any way you want, but the identifier
96 /// provided by LDK is the channel's outpoint (and it is up to you to maintain a correct
97 /// mapping between the outpoint and the stored channel data). Note that you **must** persist
98 /// every new monitor to disk.
100 /// The `update_id` is used to identify this call to [`ChainMonitor::channel_monitor_updated`],
101 /// if you return [`ChannelMonitorUpdateErr::TemporaryFailure`].
103 /// See [`Writeable::write`] on [`ChannelMonitor`] for writing out a `ChannelMonitor`
104 /// and [`ChannelMonitorUpdateErr`] for requirements when returning errors.
106 /// [`Writeable::write`]: crate::util::ser::Writeable::write
107 fn persist_new_channel(&self, channel_id: OutPoint, data: &ChannelMonitor<ChannelSigner>, update_id: MonitorUpdateId) -> Result<(), ChannelMonitorUpdateErr>;
109 /// Update one channel's data. The provided [`ChannelMonitor`] has already applied the given
112 /// Note that on every update, you **must** persist either the [`ChannelMonitorUpdate`] or the
113 /// updated monitor itself to disk/backups. See the [`Persist`] trait documentation for more
116 /// During blockchain synchronization operations, this may be called with no
117 /// [`ChannelMonitorUpdate`], in which case the full [`ChannelMonitor`] needs to be persisted.
118 /// Note that after the full [`ChannelMonitor`] is persisted any previous
119 /// [`ChannelMonitorUpdate`]s which were persisted should be discarded - they can no longer be
120 /// applied to the persisted [`ChannelMonitor`] as they were already applied.
122 /// If an implementer chooses to persist the updates only, they need to make
123 /// sure that all the updates are applied to the `ChannelMonitors` *before*
124 /// the set of channel monitors is given to the `ChannelManager`
125 /// deserialization routine. See [`ChannelMonitor::update_monitor`] for
126 /// applying a monitor update to a monitor. If full `ChannelMonitors` are
127 /// persisted, then there is no need to persist individual updates.
129 /// Note that there could be a performance tradeoff between persisting complete
130 /// channel monitors on every update vs. persisting only updates and applying
131 /// them in batches. The size of each monitor grows `O(number of state updates)`
132 /// whereas updates are small and `O(1)`.
134 /// The `update_id` is used to identify this call to [`ChainMonitor::channel_monitor_updated`],
135 /// if you return [`ChannelMonitorUpdateErr::TemporaryFailure`].
137 /// See [`Writeable::write`] on [`ChannelMonitor`] for writing out a `ChannelMonitor`,
138 /// [`Writeable::write`] on [`ChannelMonitorUpdate`] for writing out an update, and
139 /// [`ChannelMonitorUpdateErr`] for requirements when returning errors.
141 /// [`Writeable::write`]: crate::util::ser::Writeable::write
142 fn update_persisted_channel(&self, channel_id: OutPoint, update: &Option<ChannelMonitorUpdate>, data: &ChannelMonitor<ChannelSigner>, update_id: MonitorUpdateId) -> Result<(), ChannelMonitorUpdateErr>;
145 struct MonitorHolder<ChannelSigner: Sign> {
146 monitor: ChannelMonitor<ChannelSigner>,
147 /// The full set of pending monitor updates for this Channel.
149 /// Note that this lock must be held during updates to prevent a race where we call
150 /// update_persisted_channel, the user returns a TemporaryFailure, and then calls
151 /// channel_monitor_updated immediately, racing our insertion of the pending update into the
154 /// Beyond the synchronization of updates themselves, we cannot handle user events until after
155 /// any chain updates have been stored on disk. Thus, we scan this list when returning updates
156 /// to the ChannelManager, refusing to return any updates for a ChannelMonitor which is still
157 /// being persisted fully to disk after a chain update.
159 /// This avoids the possibility of handling, e.g. an on-chain claim, generating a claim monitor
160 /// event, resulting in the relevant ChannelManager generating a PaymentSent event and dropping
161 /// the pending payment entry, and then reloading before the monitor is persisted, resulting in
162 /// the ChannelManager re-adding the same payment entry, before the same block is replayed,
163 /// resulting in a duplicate PaymentSent event.
164 pending_monitor_updates: Mutex<Vec<MonitorUpdateId>>,
165 /// When the user returns a PermanentFailure error from an update_persisted_channel call during
166 /// block processing, we inform the ChannelManager that the channel should be closed
167 /// asynchronously. In order to ensure no further changes happen before the ChannelManager has
168 /// processed the closure event, we set this to true and return PermanentFailure for any other
169 /// chain::Watch events.
170 channel_perm_failed: AtomicBool,
171 /// The last block height at which no [`UpdateOrigin::ChainSync`] monitor updates were present
172 /// in `pending_monitor_updates`.
173 /// If it's been more than [`LATENCY_GRACE_PERIOD_BLOCKS`] since we started waiting on a chain
174 /// sync event, we let monitor events return to `ChannelManager` because we cannot hold them up
175 /// forever or we'll end up with HTLC preimages waiting to feed back into an upstream channel
176 /// forever, risking funds loss.
177 last_chain_persist_height: AtomicUsize,
180 impl<ChannelSigner: Sign> MonitorHolder<ChannelSigner> {
181 fn has_pending_offchain_updates(&self, pending_monitor_updates_lock: &MutexGuard<Vec<MonitorUpdateId>>) -> bool {
182 pending_monitor_updates_lock.iter().any(|update_id|
183 if let UpdateOrigin::OffChain(_) = update_id.contents { true } else { false })
185 fn has_pending_chainsync_updates(&self, pending_monitor_updates_lock: &MutexGuard<Vec<MonitorUpdateId>>) -> bool {
186 pending_monitor_updates_lock.iter().any(|update_id|
187 if let UpdateOrigin::ChainSync(_) = update_id.contents { true } else { false })
191 /// A read-only reference to a current ChannelMonitor.
193 /// Note that this holds a mutex in [`ChainMonitor`] and may block other events until it is
195 pub struct LockedChannelMonitor<'a, ChannelSigner: Sign> {
196 lock: RwLockReadGuard<'a, HashMap<OutPoint, MonitorHolder<ChannelSigner>>>,
197 funding_txo: OutPoint,
200 impl<ChannelSigner: Sign> Deref for LockedChannelMonitor<'_, ChannelSigner> {
201 type Target = ChannelMonitor<ChannelSigner>;
202 fn deref(&self) -> &ChannelMonitor<ChannelSigner> {
203 &self.lock.get(&self.funding_txo).expect("Checked at construction").monitor
207 /// An implementation of [`chain::Watch`] for monitoring channels.
209 /// Connected and disconnected blocks must be provided to `ChainMonitor` as documented by
210 /// [`chain::Watch`]. May be used in conjunction with [`ChannelManager`] to monitor channels locally
211 /// or used independently to monitor channels remotely. See the [module-level documentation] for
214 /// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
215 /// [module-level documentation]: crate::chain::chainmonitor
216 pub struct ChainMonitor<ChannelSigner: Sign, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref>
217 where C::Target: chain::Filter,
218 T::Target: BroadcasterInterface,
219 F::Target: FeeEstimator,
221 P::Target: Persist<ChannelSigner>,
223 monitors: RwLock<HashMap<OutPoint, MonitorHolder<ChannelSigner>>>,
224 /// When we generate a [`MonitorUpdateId`] for a chain-event monitor persistence, we need a
225 /// unique ID, which we calculate by simply getting the next value from this counter. Note that
226 /// the ID is never persisted so it's ok that they reset on restart.
227 sync_persistence_id: AtomicCounter,
228 chain_source: Option<C>,
233 /// "User-provided" (ie persistence-completion/-failed) [`MonitorEvent`]s. These came directly
234 /// from the user and not from a [`ChannelMonitor`].
235 pending_monitor_events: Mutex<Vec<MonitorEvent>>,
236 /// The best block height seen, used as a proxy for the passage of time.
237 highest_chain_height: AtomicUsize,
240 impl<ChannelSigner: Sign, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref> ChainMonitor<ChannelSigner, C, T, F, L, P>
241 where C::Target: chain::Filter,
242 T::Target: BroadcasterInterface,
243 F::Target: FeeEstimator,
245 P::Target: Persist<ChannelSigner>,
247 /// Dispatches to per-channel monitors, which are responsible for updating their on-chain view
248 /// of a channel and reacting accordingly based on transactions in the given chain data. See
249 /// [`ChannelMonitor::block_connected`] for details. Any HTLCs that were resolved on chain will
250 /// be returned by [`chain::Watch::release_pending_monitor_events`].
252 /// Calls back to [`chain::Filter`] if any monitor indicated new outputs to watch. Subsequent
253 /// calls must not exclude any transactions matching the new outputs nor any in-block
254 /// descendants of such transactions. It is not necessary to re-fetch the block to obtain
255 /// updated `txdata`.
257 /// Calls which represent a new blockchain tip height should set `best_height`.
258 fn process_chain_data<FN>(&self, header: &BlockHeader, best_height: Option<u32>, txdata: &TransactionData, process: FN)
260 FN: Fn(&ChannelMonitor<ChannelSigner>, &TransactionData) -> Vec<TransactionOutputs>
262 let mut dependent_txdata = Vec::new();
264 let monitor_states = self.monitors.write().unwrap();
265 if let Some(height) = best_height {
266 // If the best block height is being updated, update highest_chain_height under the
267 // monitors write lock.
268 let old_height = self.highest_chain_height.load(Ordering::Acquire);
269 let new_height = height as usize;
270 if new_height > old_height {
271 self.highest_chain_height.store(new_height, Ordering::Release);
275 for (funding_outpoint, monitor_state) in monitor_states.iter() {
276 let monitor = &monitor_state.monitor;
279 txn_outputs = process(monitor, txdata);
280 let update_id = MonitorUpdateId {
281 contents: UpdateOrigin::ChainSync(self.sync_persistence_id.get_increment()),
283 let mut pending_monitor_updates = monitor_state.pending_monitor_updates.lock().unwrap();
284 if let Some(height) = best_height {
285 if !monitor_state.has_pending_chainsync_updates(&pending_monitor_updates) {
286 // If there are not ChainSync persists awaiting completion, go ahead and
287 // set last_chain_persist_height here - we wouldn't want the first
288 // TemporaryFailure to always immediately be considered "overly delayed".
289 monitor_state.last_chain_persist_height.store(height as usize, Ordering::Release);
293 log_trace!(self.logger, "Syncing Channel Monitor for channel {}", log_funding_info!(monitor));
294 match self.persister.update_persisted_channel(*funding_outpoint, &None, monitor, update_id) {
296 log_trace!(self.logger, "Finished syncing Channel Monitor for channel {}", log_funding_info!(monitor)),
297 Err(ChannelMonitorUpdateErr::PermanentFailure) => {
298 monitor_state.channel_perm_failed.store(true, Ordering::Release);
299 self.pending_monitor_events.lock().unwrap().push(MonitorEvent::UpdateFailed(*funding_outpoint));
301 Err(ChannelMonitorUpdateErr::TemporaryFailure) => {
302 log_debug!(self.logger, "Channel Monitor sync for channel {} in progress, holding events until completion!", log_funding_info!(monitor));
303 pending_monitor_updates.push(update_id);
308 // Register any new outputs with the chain source for filtering, storing any dependent
309 // transactions from within the block that previously had not been included in txdata.
310 if let Some(ref chain_source) = self.chain_source {
311 let block_hash = header.block_hash();
312 for (txid, mut outputs) in txn_outputs.drain(..) {
313 for (idx, output) in outputs.drain(..) {
314 // Register any new outputs with the chain source for filtering and recurse
315 // if it indicates that there are dependent transactions within the block
316 // that had not been previously included in txdata.
317 let output = WatchedOutput {
318 block_hash: Some(block_hash),
319 outpoint: OutPoint { txid, index: idx as u16 },
320 script_pubkey: output.script_pubkey,
322 if let Some(tx) = chain_source.register_output(output) {
323 dependent_txdata.push(tx);
331 // Recursively call for any dependent transactions that were identified by the chain source.
332 if !dependent_txdata.is_empty() {
333 dependent_txdata.sort_unstable_by_key(|(index, _tx)| *index);
334 dependent_txdata.dedup_by_key(|(index, _tx)| *index);
335 let txdata: Vec<_> = dependent_txdata.iter().map(|(index, tx)| (*index, tx)).collect();
336 self.process_chain_data(header, None, &txdata, process); // We skip the best height the second go-around
340 /// Creates a new `ChainMonitor` used to watch on-chain activity pertaining to channels.
342 /// When an optional chain source implementing [`chain::Filter`] is provided, the chain monitor
343 /// will call back to it indicating transactions and outputs of interest. This allows clients to
344 /// pre-filter blocks or only fetch blocks matching a compact filter. Otherwise, clients may
345 /// always need to fetch full blocks absent another means for determining which blocks contain
346 /// transactions relevant to the watched channels.
347 pub fn new(chain_source: Option<C>, broadcaster: T, logger: L, feeest: F, persister: P) -> Self {
349 monitors: RwLock::new(HashMap::new()),
350 sync_persistence_id: AtomicCounter::new(),
354 fee_estimator: feeest,
356 pending_monitor_events: Mutex::new(Vec::new()),
357 highest_chain_height: AtomicUsize::new(0),
361 /// Gets the balances in the contained [`ChannelMonitor`]s which are claimable on-chain or
362 /// claims which are awaiting confirmation.
364 /// Includes the balances from each [`ChannelMonitor`] *except* those included in
365 /// `ignored_channels`, allowing you to filter out balances from channels which are still open
366 /// (and whose balance should likely be pulled from the [`ChannelDetails`]).
368 /// See [`ChannelMonitor::get_claimable_balances`] for more details on the exact criteria for
369 /// inclusion in the return value.
370 pub fn get_claimable_balances(&self, ignored_channels: &[&ChannelDetails]) -> Vec<Balance> {
371 let mut ret = Vec::new();
372 let monitor_states = self.monitors.read().unwrap();
373 for (_, monitor_state) in monitor_states.iter().filter(|(funding_outpoint, _)| {
374 for chan in ignored_channels {
375 if chan.funding_txo.as_ref() == Some(funding_outpoint) {
381 ret.append(&mut monitor_state.monitor.get_claimable_balances());
386 /// Gets the [`LockedChannelMonitor`] for a given funding outpoint, returning an `Err` if no
387 /// such [`ChannelMonitor`] is currently being monitored for.
389 /// Note that the result holds a mutex over our monitor set, and should not be held
391 pub fn get_monitor(&self, funding_txo: OutPoint) -> Result<LockedChannelMonitor<'_, ChannelSigner>, ()> {
392 let lock = self.monitors.read().unwrap();
393 if lock.get(&funding_txo).is_some() {
394 Ok(LockedChannelMonitor { lock, funding_txo })
400 /// Lists the funding outpoint of each [`ChannelMonitor`] being monitored.
402 /// Note that [`ChannelMonitor`]s are not removed when a channel is closed as they are always
403 /// monitoring for on-chain state resolutions.
404 pub fn list_monitors(&self) -> Vec<OutPoint> {
405 self.monitors.read().unwrap().keys().map(|outpoint| *outpoint).collect()
409 pub fn remove_monitor(&self, funding_txo: &OutPoint) -> ChannelMonitor<ChannelSigner> {
410 self.monitors.write().unwrap().remove(funding_txo).unwrap().monitor
413 /// Indicates the persistence of a [`ChannelMonitor`] has completed after
414 /// [`ChannelMonitorUpdateErr::TemporaryFailure`] was returned from an update operation.
416 /// Thus, the anticipated use is, at a high level:
417 /// 1) This [`ChainMonitor`] calls [`Persist::update_persisted_channel`] which stores the
418 /// update to disk and begins updating any remote (e.g. watchtower/backup) copies,
419 /// returning [`ChannelMonitorUpdateErr::TemporaryFailure`],
420 /// 2) once all remote copies are updated, you call this function with the
421 /// `completed_update_id` that completed, and once all pending updates have completed the
422 /// channel will be re-enabled.
423 // Note that we re-enable only after `UpdateOrigin::OffChain` updates complete, we don't
424 // care about `UpdateOrigin::ChainSync` updates for the channel state being updated. We
425 // only care about `UpdateOrigin::ChainSync` for returning `MonitorEvent`s.
427 /// Returns an [`APIError::APIMisuseError`] if `funding_txo` does not match any currently
428 /// registered [`ChannelMonitor`]s.
429 pub fn channel_monitor_updated(&self, funding_txo: OutPoint, completed_update_id: MonitorUpdateId) -> Result<(), APIError> {
430 let monitors = self.monitors.read().unwrap();
431 let monitor_data = if let Some(mon) = monitors.get(&funding_txo) { mon } else {
432 return Err(APIError::APIMisuseError { err: format!("No ChannelMonitor matching funding outpoint {:?} found", funding_txo) });
434 let mut pending_monitor_updates = monitor_data.pending_monitor_updates.lock().unwrap();
435 pending_monitor_updates.retain(|update_id| *update_id != completed_update_id);
437 match completed_update_id {
438 MonitorUpdateId { contents: UpdateOrigin::OffChain(_) } => {
439 // Note that we only check for `UpdateOrigin::OffChain` failures here - if
440 // we're being told that a `UpdateOrigin::OffChain` monitor update completed,
441 // we only care about ensuring we don't tell the `ChannelManager` to restore
442 // the channel to normal operation until all `UpdateOrigin::OffChain` updates
444 // If there's some `UpdateOrigin::ChainSync` update still pending that's okay
445 // - we can still update our channel state, just as long as we don't return
446 // `MonitorEvent`s from the monitor back to the `ChannelManager` until they
448 let monitor_is_pending_updates = monitor_data.has_pending_offchain_updates(&pending_monitor_updates);
449 if monitor_is_pending_updates || monitor_data.channel_perm_failed.load(Ordering::Acquire) {
450 // If there are still monitor updates pending (or an old monitor update
451 // finished after a later one perm-failed), we cannot yet construct an
452 // UpdateCompleted event.
455 self.pending_monitor_events.lock().unwrap().push(MonitorEvent::UpdateCompleted {
457 monitor_update_id: monitor_data.monitor.get_latest_update_id(),
460 MonitorUpdateId { contents: UpdateOrigin::ChainSync(_) } => {
461 if !monitor_data.has_pending_chainsync_updates(&pending_monitor_updates) {
462 monitor_data.last_chain_persist_height.store(self.highest_chain_height.load(Ordering::Acquire), Ordering::Release);
463 // The next time release_pending_monitor_events is called, any events for this
464 // ChannelMonitor will be returned.
471 /// This wrapper avoids having to update some of our tests for now as they assume the direct
472 /// chain::Watch API wherein we mark a monitor fully-updated by just calling
473 /// channel_monitor_updated once with the highest ID.
474 #[cfg(any(test, feature = "fuzztarget"))]
475 pub fn force_channel_monitor_updated(&self, funding_txo: OutPoint, monitor_update_id: u64) {
476 self.pending_monitor_events.lock().unwrap().push(MonitorEvent::UpdateCompleted {
482 #[cfg(any(test, feature = "fuzztarget", feature = "_test_utils"))]
483 pub fn get_and_clear_pending_events(&self) -> Vec<events::Event> {
484 use util::events::EventsProvider;
485 let events = core::cell::RefCell::new(Vec::new());
486 let event_handler = |event: &events::Event| events.borrow_mut().push(event.clone());
487 self.process_pending_events(&event_handler);
492 impl<ChannelSigner: Sign, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref>
493 chain::Listen for ChainMonitor<ChannelSigner, C, T, F, L, P>
495 C::Target: chain::Filter,
496 T::Target: BroadcasterInterface,
497 F::Target: FeeEstimator,
499 P::Target: Persist<ChannelSigner>,
501 fn block_connected(&self, block: &Block, height: u32) {
502 let header = &block.header;
503 let txdata: Vec<_> = block.txdata.iter().enumerate().collect();
504 log_debug!(self.logger, "New best block {} at height {} provided via block_connected", header.block_hash(), height);
505 self.process_chain_data(header, Some(height), &txdata, |monitor, txdata| {
506 monitor.block_connected(
507 header, txdata, height, &*self.broadcaster, &*self.fee_estimator, &*self.logger)
511 fn block_disconnected(&self, header: &BlockHeader, height: u32) {
512 let monitor_states = self.monitors.read().unwrap();
513 log_debug!(self.logger, "Latest block {} at height {} removed via block_disconnected", header.block_hash(), height);
514 for monitor_state in monitor_states.values() {
515 monitor_state.monitor.block_disconnected(
516 header, height, &*self.broadcaster, &*self.fee_estimator, &*self.logger);
521 impl<ChannelSigner: Sign, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref>
522 chain::Confirm for ChainMonitor<ChannelSigner, C, T, F, L, P>
524 C::Target: chain::Filter,
525 T::Target: BroadcasterInterface,
526 F::Target: FeeEstimator,
528 P::Target: Persist<ChannelSigner>,
530 fn transactions_confirmed(&self, header: &BlockHeader, txdata: &TransactionData, height: u32) {
531 log_debug!(self.logger, "{} provided transactions confirmed at height {} in block {}", txdata.len(), height, header.block_hash());
532 self.process_chain_data(header, None, txdata, |monitor, txdata| {
533 monitor.transactions_confirmed(
534 header, txdata, height, &*self.broadcaster, &*self.fee_estimator, &*self.logger)
538 fn transaction_unconfirmed(&self, txid: &Txid) {
539 log_debug!(self.logger, "Transaction {} reorganized out of chain", txid);
540 let monitor_states = self.monitors.read().unwrap();
541 for monitor_state in monitor_states.values() {
542 monitor_state.monitor.transaction_unconfirmed(txid, &*self.broadcaster, &*self.fee_estimator, &*self.logger);
546 fn best_block_updated(&self, header: &BlockHeader, height: u32) {
547 log_debug!(self.logger, "New best block {} at height {} provided via best_block_updated", header.block_hash(), height);
548 self.process_chain_data(header, Some(height), &[], |monitor, txdata| {
549 // While in practice there shouldn't be any recursive calls when given empty txdata,
550 // it's still possible if a chain::Filter implementation returns a transaction.
551 debug_assert!(txdata.is_empty());
552 monitor.best_block_updated(
553 header, height, &*self.broadcaster, &*self.fee_estimator, &*self.logger)
557 fn get_relevant_txids(&self) -> Vec<Txid> {
558 let mut txids = Vec::new();
559 let monitor_states = self.monitors.read().unwrap();
560 for monitor_state in monitor_states.values() {
561 txids.append(&mut monitor_state.monitor.get_relevant_txids());
564 txids.sort_unstable();
570 impl<ChannelSigner: Sign, C: Deref , T: Deref , F: Deref , L: Deref , P: Deref >
571 chain::Watch<ChannelSigner> for ChainMonitor<ChannelSigner, C, T, F, L, P>
572 where C::Target: chain::Filter,
573 T::Target: BroadcasterInterface,
574 F::Target: FeeEstimator,
576 P::Target: Persist<ChannelSigner>,
578 /// Adds the monitor that watches the channel referred to by the given outpoint.
580 /// Calls back to [`chain::Filter`] with the funding transaction and outputs to watch.
582 /// Note that we persist the given `ChannelMonitor` while holding the `ChainMonitor`
584 fn watch_channel(&self, funding_outpoint: OutPoint, monitor: ChannelMonitor<ChannelSigner>) -> Result<(), ChannelMonitorUpdateErr> {
585 let mut monitors = self.monitors.write().unwrap();
586 let entry = match monitors.entry(funding_outpoint) {
587 hash_map::Entry::Occupied(_) => {
588 log_error!(self.logger, "Failed to add new channel data: channel monitor for given outpoint is already present");
589 return Err(ChannelMonitorUpdateErr::PermanentFailure)},
590 hash_map::Entry::Vacant(e) => e,
592 let update_id = MonitorUpdateId::from_new_monitor(&monitor);
593 let mut pending_monitor_updates = Vec::new();
594 let persist_res = self.persister.persist_new_channel(funding_outpoint, &monitor, update_id);
595 if persist_res.is_err() {
596 log_error!(self.logger, "Failed to persist new channel data: {:?}", persist_res);
598 if persist_res == Err(ChannelMonitorUpdateErr::PermanentFailure) {
600 } else if persist_res.is_err() {
601 pending_monitor_updates.push(update_id);
604 let funding_txo = monitor.get_funding_txo();
605 log_trace!(self.logger, "Got new Channel Monitor for channel {}", log_bytes!(funding_txo.0.to_channel_id()[..]));
607 if let Some(ref chain_source) = self.chain_source {
608 monitor.load_outputs_to_watch(chain_source);
611 entry.insert(MonitorHolder {
613 pending_monitor_updates: Mutex::new(pending_monitor_updates),
614 channel_perm_failed: AtomicBool::new(false),
615 last_chain_persist_height: AtomicUsize::new(self.highest_chain_height.load(Ordering::Acquire)),
620 /// Note that we persist the given `ChannelMonitor` update while holding the
621 /// `ChainMonitor` monitors lock.
622 fn update_channel(&self, funding_txo: OutPoint, update: ChannelMonitorUpdate) -> Result<(), ChannelMonitorUpdateErr> {
623 // Update the monitor that watches the channel referred to by the given outpoint.
624 let monitors = self.monitors.read().unwrap();
625 match monitors.get(&funding_txo) {
627 log_error!(self.logger, "Failed to update channel monitor: no such monitor registered");
629 // We should never ever trigger this from within ChannelManager. Technically a
630 // user could use this object with some proxying in between which makes this
631 // possible, but in tests and fuzzing, this should be a panic.
632 #[cfg(any(test, feature = "fuzztarget"))]
633 panic!("ChannelManager generated a channel update for a channel that was not yet registered!");
634 #[cfg(not(any(test, feature = "fuzztarget")))]
635 Err(ChannelMonitorUpdateErr::PermanentFailure)
637 Some(monitor_state) => {
638 let monitor = &monitor_state.monitor;
639 log_trace!(self.logger, "Updating Channel Monitor for channel {}", log_funding_info!(monitor));
640 let update_res = monitor.update_monitor(&update, &self.broadcaster, &self.fee_estimator, &self.logger);
641 if let Err(e) = &update_res {
642 log_error!(self.logger, "Failed to update channel monitor: {:?}", e);
644 // Even if updating the monitor returns an error, the monitor's state will
645 // still be changed. So, persist the updated monitor despite the error.
646 let update_id = MonitorUpdateId::from_monitor_update(&update);
647 let mut pending_monitor_updates = monitor_state.pending_monitor_updates.lock().unwrap();
648 let persist_res = self.persister.update_persisted_channel(funding_txo, &Some(update), monitor, update_id);
649 if let Err(e) = persist_res {
650 if e == ChannelMonitorUpdateErr::TemporaryFailure {
651 pending_monitor_updates.push(update_id);
653 monitor_state.channel_perm_failed.store(true, Ordering::Release);
655 log_error!(self.logger, "Failed to persist channel monitor update: {:?}", e);
657 if update_res.is_err() {
658 Err(ChannelMonitorUpdateErr::PermanentFailure)
659 } else if monitor_state.channel_perm_failed.load(Ordering::Acquire) {
660 Err(ChannelMonitorUpdateErr::PermanentFailure)
668 fn release_pending_monitor_events(&self) -> Vec<MonitorEvent> {
669 let mut pending_monitor_events = self.pending_monitor_events.lock().unwrap().split_off(0);
670 for monitor_state in self.monitors.read().unwrap().values() {
671 let is_pending_monitor_update = monitor_state.has_pending_chainsync_updates(&monitor_state.pending_monitor_updates.lock().unwrap());
672 if is_pending_monitor_update &&
673 monitor_state.last_chain_persist_height.load(Ordering::Acquire) + LATENCY_GRACE_PERIOD_BLOCKS as usize
674 > self.highest_chain_height.load(Ordering::Acquire)
676 log_info!(self.logger, "A Channel Monitor sync is still in progress, refusing to provide monitor events!");
678 if monitor_state.channel_perm_failed.load(Ordering::Acquire) {
679 // If a `UpdateOrigin::ChainSync` persistence failed with `PermanantFailure`,
680 // we don't really know if the latest `ChannelMonitor` state is on disk or not.
681 // We're supposed to hold monitor updates until the latest state is on disk to
682 // avoid duplicate events, but the user told us persistence is screw-y and may
683 // not complete. We can't hold events forever because we may learn some payment
684 // preimage, so instead we just log and hope the user complied with the
685 // `PermanentFailure` requirements of having at least the local-disk copy
687 log_info!(self.logger, "A Channel Monitor sync returned PermanentFailure. Returning monitor events but duplicate events may appear after reload!");
689 if is_pending_monitor_update {
690 log_error!(self.logger, "A ChannelMonitor sync took longer than {} blocks to complete.", LATENCY_GRACE_PERIOD_BLOCKS);
691 log_error!(self.logger, " To avoid funds-loss, we are allowing monitor updates to be released.");
692 log_error!(self.logger, " This may cause duplicate payment events to be generated.");
694 pending_monitor_events.append(&mut monitor_state.monitor.get_and_clear_pending_monitor_events());
697 pending_monitor_events
701 impl<ChannelSigner: Sign, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref> events::EventsProvider for ChainMonitor<ChannelSigner, C, T, F, L, P>
702 where C::Target: chain::Filter,
703 T::Target: BroadcasterInterface,
704 F::Target: FeeEstimator,
706 P::Target: Persist<ChannelSigner>,
708 /// Processes [`SpendableOutputs`] events produced from each [`ChannelMonitor`] upon maturity.
710 /// An [`EventHandler`] may safely call back to the provider, though this shouldn't be needed in
711 /// order to handle these events.
713 /// [`SpendableOutputs`]: events::Event::SpendableOutputs
714 fn process_pending_events<H: Deref>(&self, handler: H) where H::Target: EventHandler {
715 let mut pending_events = Vec::new();
716 for monitor_state in self.monitors.read().unwrap().values() {
717 pending_events.append(&mut monitor_state.monitor.get_and_clear_pending_events());
719 for event in pending_events.drain(..) {
720 handler.handle_event(&event);
727 use ::{check_added_monitors, get_local_commitment_txn};
728 use ln::features::InitFeatures;
729 use ln::functional_test_utils::*;
730 use util::events::MessageSendEventsProvider;
731 use util::test_utils::{OnRegisterOutput, TxOutReference};
733 /// Tests that in-block dependent transactions are processed by `block_connected` when not
734 /// included in `txdata` but returned by [`chain::Filter::register_output`]. For instance,
735 /// a (non-anchor) commitment transaction's HTLC output may be spent in the same block as the
736 /// commitment transaction itself. An Electrum client may filter the commitment transaction but
737 /// needs to return the HTLC transaction so it can be processed.
739 fn connect_block_checks_dependent_transactions() {
740 let chanmon_cfgs = create_chanmon_cfgs(2);
741 let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
742 let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
743 let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
744 let channel = create_announced_chan_between_nodes(
745 &nodes, 0, 1, InitFeatures::known(), InitFeatures::known());
747 // Send a payment, saving nodes[0]'s revoked commitment and HTLC-Timeout transactions.
748 let (commitment_tx, htlc_tx) = {
749 let payment_preimage = route_payment(&nodes[0], &vec!(&nodes[1])[..], 5_000_000).0;
750 let mut txn = get_local_commitment_txn!(nodes[0], channel.2);
751 claim_payment(&nodes[0], &vec!(&nodes[1])[..], payment_preimage);
753 assert_eq!(txn.len(), 2);
754 (txn.remove(0), txn.remove(0))
757 // Set expectations on nodes[1]'s chain source to return dependent transactions.
758 let htlc_output = TxOutReference(commitment_tx.clone(), 0);
759 let to_local_output = TxOutReference(commitment_tx.clone(), 1);
760 let htlc_timeout_output = TxOutReference(htlc_tx.clone(), 0);
761 nodes[1].chain_source
762 .expect(OnRegisterOutput { with: htlc_output, returns: Some((1, htlc_tx)) })
763 .expect(OnRegisterOutput { with: to_local_output, returns: None })
764 .expect(OnRegisterOutput { with: htlc_timeout_output, returns: None });
766 // Notify nodes[1] that nodes[0]'s revoked commitment transaction was mined. The chain
767 // source should return the dependent HTLC transaction when the HTLC output is registered.
768 mine_transaction(&nodes[1], &commitment_tx);
770 // Clean up so uninteresting assertions don't fail.
771 check_added_monitors!(nodes[1], 1);
772 nodes[1].node.get_and_clear_pending_msg_events();
773 nodes[1].node.get_and_clear_pending_events();