Merge pull request #2676 from TheBlueMatt/2023-10-various-followups
[rust-lightning] / lightning / src / chain / chainmonitor.rs
index 74e520a2a376cc7296fc2d9a1ab9efd56e3f0f3e..e87d082d9a7bb9061894ce26fb15da0087a7c173 100644 (file)
 //! servicing [`ChannelMonitor`] updates from the client.
 
 use bitcoin::blockdata::block::BlockHeader;
-use bitcoin::hash_types::Txid;
+use bitcoin::hash_types::{Txid, BlockHash};
 
 use crate::chain;
 use crate::chain::{ChannelMonitorUpdateStatus, Filter, WatchedOutput};
 use crate::chain::chaininterface::{BroadcasterInterface, FeeEstimator};
 use crate::chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, Balance, MonitorEvent, TransactionOutputs, LATENCY_GRACE_PERIOD_BLOCKS};
 use crate::chain::transaction::{OutPoint, TransactionData};
-use crate::chain::keysinterface::Sign;
+use crate::sign::WriteableEcdsaChannelSigner;
+use crate::events;
+use crate::events::{Event, EventHandler};
 use crate::util::atomic_counter::AtomicCounter;
 use crate::util::logger::Logger;
 use crate::util::errors::APIError;
-use crate::util::events;
-use crate::util::events::EventHandler;
+use crate::util::wakers::{Future, Notifier};
 use crate::ln::channelmanager::ChannelDetails;
 
 use crate::prelude::*;
 use crate::sync::{RwLock, RwLockReadGuard, Mutex, MutexGuard};
+use core::iter::FromIterator;
 use core::ops::Deref;
-use core::sync::atomic::{AtomicBool, AtomicUsize, Ordering};
+use core::sync::atomic::{AtomicUsize, Ordering};
 use bitcoin::secp256k1::PublicKey;
 
-#[derive(Clone, Copy, Hash, PartialEq, Eq)]
-/// A specific update's ID stored in a `MonitorUpdateId`, separated out to make the contents
-/// entirely opaque.
-enum UpdateOrigin {
-       /// An update that was generated by the `ChannelManager` (via our `chain::Watch`
-       /// implementation). This corresponds to an actual [`ChannelMonitorUpdate::update_id`] field
-       /// and [`ChannelMonitor::get_latest_update_id`].
-       OffChain(u64),
-       /// An update that was generated during blockchain processing. The ID here is specific to the
-       /// generating [`ChainMonitor`] and does *not* correspond to any on-disk IDs.
-       ChainSync(u64),
+mod update_origin {
+       #[derive(Debug, Clone, Copy, Hash, PartialEq, Eq)]
+       /// A specific update's ID stored in a `MonitorUpdateId`, separated out to make the contents
+       /// entirely opaque.
+       pub(crate) enum UpdateOrigin {
+               /// An update that was generated by the `ChannelManager` (via our [`crate::chain::Watch`]
+               /// implementation). This corresponds to an actual [ChannelMonitorUpdate::update_id] field
+               /// and [ChannelMonitor::get_latest_update_id].
+               ///
+               /// [ChannelMonitor::get_latest_update_id]: crate::chain::channelmonitor::ChannelMonitor::get_latest_update_id
+               /// [ChannelMonitorUpdate::update_id]: crate::chain::channelmonitor::ChannelMonitorUpdate::update_id
+               OffChain(u64),
+               /// An update that was generated during blockchain processing. The ID here is specific to the
+               /// generating [ChannelMonitor] and does *not* correspond to any on-disk IDs.
+               ///
+               /// [ChannelMonitor]: crate::chain::channelmonitor::ChannelMonitor
+               ChainSync(u64),
+       }
 }
 
+#[cfg(any(feature = "_test_utils", test))]
+pub(crate) use update_origin::UpdateOrigin;
+#[cfg(not(any(feature = "_test_utils", test)))]
+use update_origin::UpdateOrigin;
+
 /// An opaque identifier describing a specific [`Persist`] method call.
-#[derive(Clone, Copy, Hash, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, Hash, PartialEq, Eq)]
 pub struct MonitorUpdateId {
-       contents: UpdateOrigin,
+       pub(crate) contents: UpdateOrigin,
 }
 
 impl MonitorUpdateId {
        pub(crate) fn from_monitor_update(update: &ChannelMonitorUpdate) -> Self {
                Self { contents: UpdateOrigin::OffChain(update.update_id) }
        }
-       pub(crate) fn from_new_monitor<ChannelSigner: Sign>(monitor: &ChannelMonitor<ChannelSigner>) -> Self {
+       pub(crate) fn from_new_monitor<ChannelSigner: WriteableEcdsaChannelSigner>(monitor: &ChannelMonitor<ChannelSigner>) -> Self {
                Self { contents: UpdateOrigin::OffChain(monitor.get_latest_update_id()) }
        }
 }
@@ -76,24 +90,59 @@ impl MonitorUpdateId {
 /// `Persist` defines behavior for persisting channel monitors: this could mean
 /// writing once to disk, and/or uploading to one or more backup services.
 ///
-/// Each method can return three possible values:
-///  * If persistence (including any relevant `fsync()` calls) happens immediately, the
-///    implementation should return [`ChannelMonitorUpdateStatus::Completed`], indicating normal
-///    channel operation should continue.
-///  * If persistence happens asynchronously, implementations should first ensure the
-///    [`ChannelMonitor`] or [`ChannelMonitorUpdate`] are written durably to disk, and then return
-///    [`ChannelMonitorUpdateStatus::InProgress`] while the update continues in the background.
-///    Once the update completes, [`ChainMonitor::channel_monitor_updated`] should be called with
-///    the corresponding [`MonitorUpdateId`].
+/// Persistence can happen in one of two ways - synchronously completing before the trait method
+/// calls return or asynchronously in the background.
+///
+/// # For those implementing synchronous persistence
+///
+///  * If persistence completes fully (including any relevant `fsync()` calls), the implementation
+///    should return [`ChannelMonitorUpdateStatus::Completed`], indicating normal channel operation
+///    should continue.
+///
+///  * If persistence fails for some reason, implementations should consider returning
+///    [`ChannelMonitorUpdateStatus::InProgress`] and retry all pending persistence operations in
+///    the background with [`ChainMonitor::list_pending_monitor_updates`] and
+///    [`ChainMonitor::get_monitor`].
+///
+///    Once a full [`ChannelMonitor`] has been persisted, all pending updates for that channel can
+///    be marked as complete via [`ChainMonitor::channel_monitor_updated`].
+///
+///    If at some point no further progress can be made towards persisting the pending updates, the
+///    node should simply shut down.
+///
+///  * If the persistence has failed and cannot be retried further (e.g. because of an outage),
+///    [`ChannelMonitorUpdateStatus::UnrecoverableError`] can be used, though this will result in
+///    an immediate panic and future operations in LDK generally failing.
+///
+/// # For those implementing asynchronous persistence
+///
+///  All calls should generally spawn a background task and immediately return
+///  [`ChannelMonitorUpdateStatus::InProgress`]. Once the update completes,
+///  [`ChainMonitor::channel_monitor_updated`] should be called with the corresponding
+///  [`MonitorUpdateId`].
+///
+///  Note that unlike the direct [`chain::Watch`] interface,
+///  [`ChainMonitor::channel_monitor_updated`] must be called once for *each* update which occurs.
+///
+///  If at some point no further progress can be made towards persisting a pending update, the node
+///  should simply shut down. Until then, the background task should either loop indefinitely, or
+///  persistence should be regularly retried with [`ChainMonitor::list_pending_monitor_updates`]
+///  and [`ChainMonitor::get_monitor`] (note that if a full monitor is persisted all pending
+///  monitor updates may be marked completed).
 ///
-///    Note that unlike the direct [`chain::Watch`] interface,
-///    [`ChainMonitor::channel_monitor_updated`] must be called once for *each* update which occurs.
+/// # Using remote watchtowers
 ///
-///  * If persistence fails for some reason, implementations should return
-///    [`ChannelMonitorUpdateStatus::PermanentFailure`], in which case the channel will likely be
-///    closed without broadcasting the latest state. See
-///    [`ChannelMonitorUpdateStatus::PermanentFailure`] for more details.
-pub trait Persist<ChannelSigner: Sign> {
+/// Watchtowers may be updated as a part of an implementation of this trait, utilizing the async
+/// update process described above while the watchtower is being updated. The following methods are
+/// provided for bulding transactions for a watchtower:
+/// [`ChannelMonitor::initial_counterparty_commitment_tx`],
+/// [`ChannelMonitor::counterparty_commitment_txs_from_update`],
+/// [`ChannelMonitor::sign_to_local_justice_tx`], [`TrustedCommitmentTransaction::revokeable_output_index`],
+/// [`TrustedCommitmentTransaction::build_to_local_justice_tx`].
+///
+/// [`TrustedCommitmentTransaction::revokeable_output_index`]: crate::ln::chan_utils::TrustedCommitmentTransaction::revokeable_output_index
+/// [`TrustedCommitmentTransaction::build_to_local_justice_tx`]: crate::ln::chan_utils::TrustedCommitmentTransaction::build_to_local_justice_tx
+pub trait Persist<ChannelSigner: WriteableEcdsaChannelSigner> {
        /// Persist a new channel's data in response to a [`chain::Watch::watch_channel`] call. This is
        /// called by [`ChannelManager`] for new channels, or may be called directly, e.g. on startup.
        ///
@@ -118,8 +167,8 @@ pub trait Persist<ChannelSigner: Sign> {
        /// updated monitor itself to disk/backups. See the [`Persist`] trait documentation for more
        /// details.
        ///
-       /// During blockchain synchronization operations, this may be called with no
-       /// [`ChannelMonitorUpdate`], in which case the full [`ChannelMonitor`] needs to be persisted.
+       /// During blockchain synchronization operations, and in some rare cases, this may be called with
+       /// no [`ChannelMonitorUpdate`], in which case the full [`ChannelMonitor`] needs to be persisted.
        /// Note that after the full [`ChannelMonitor`] is persisted any previous
        /// [`ChannelMonitorUpdate`]s which were persisted should be discarded - they can no longer be
        /// applied to the persisted [`ChannelMonitor`] as they were already applied.
@@ -144,10 +193,10 @@ pub trait Persist<ChannelSigner: Sign> {
        /// [`ChannelMonitorUpdateStatus`] for requirements when returning errors.
        ///
        /// [`Writeable::write`]: crate::util::ser::Writeable::write
-       fn update_persisted_channel(&self, channel_id: OutPoint, update: &Option<ChannelMonitorUpdate>, data: &ChannelMonitor<ChannelSigner>, update_id: MonitorUpdateId) -> ChannelMonitorUpdateStatus;
+       fn update_persisted_channel(&self, channel_id: OutPoint, update: Option<&ChannelMonitorUpdate>, data: &ChannelMonitor<ChannelSigner>, update_id: MonitorUpdateId) -> ChannelMonitorUpdateStatus;
 }
 
-struct MonitorHolder<ChannelSigner: Sign> {
+struct MonitorHolder<ChannelSigner: WriteableEcdsaChannelSigner> {
        monitor: ChannelMonitor<ChannelSigner>,
        /// The full set of pending monitor updates for this Channel.
        ///
@@ -167,12 +216,6 @@ struct MonitorHolder<ChannelSigner: Sign> {
        /// the ChannelManager re-adding the same payment entry, before the same block is replayed,
        /// resulting in a duplicate PaymentSent event.
        pending_monitor_updates: Mutex<Vec<MonitorUpdateId>>,
-       /// When the user returns a PermanentFailure error from an update_persisted_channel call during
-       /// block processing, we inform the ChannelManager that the channel should be closed
-       /// asynchronously. In order to ensure no further changes happen before the ChannelManager has
-       /// processed the closure event, we set this to true and return PermanentFailure for any other
-       /// chain::Watch events.
-       channel_perm_failed: AtomicBool,
        /// The last block height at which no [`UpdateOrigin::ChainSync`] monitor updates were present
        /// in `pending_monitor_updates`.
        /// If it's been more than [`LATENCY_GRACE_PERIOD_BLOCKS`] since we started waiting on a chain
@@ -182,7 +225,7 @@ struct MonitorHolder<ChannelSigner: Sign> {
        last_chain_persist_height: AtomicUsize,
 }
 
-impl<ChannelSigner: Sign> MonitorHolder<ChannelSigner> {
+impl<ChannelSigner: WriteableEcdsaChannelSigner> MonitorHolder<ChannelSigner> {
        fn has_pending_offchain_updates(&self, pending_monitor_updates_lock: &MutexGuard<Vec<MonitorUpdateId>>) -> bool {
                pending_monitor_updates_lock.iter().any(|update_id|
                        if let UpdateOrigin::OffChain(_) = update_id.contents { true } else { false })
@@ -197,12 +240,12 @@ impl<ChannelSigner: Sign> MonitorHolder<ChannelSigner> {
 ///
 /// Note that this holds a mutex in [`ChainMonitor`] and may block other events until it is
 /// released.
-pub struct LockedChannelMonitor<'a, ChannelSigner: Sign> {
+pub struct LockedChannelMonitor<'a, ChannelSigner: WriteableEcdsaChannelSigner> {
        lock: RwLockReadGuard<'a, HashMap<OutPoint, MonitorHolder<ChannelSigner>>>,
        funding_txo: OutPoint,
 }
 
-impl<ChannelSigner: Sign> Deref for LockedChannelMonitor<'_, ChannelSigner> {
+impl<ChannelSigner: WriteableEcdsaChannelSigner> Deref for LockedChannelMonitor<'_, ChannelSigner> {
        type Target = ChannelMonitor<ChannelSigner>;
        fn deref(&self) -> &ChannelMonitor<ChannelSigner> {
                &self.lock.get(&self.funding_txo).expect("Checked at construction").monitor
@@ -216,9 +259,16 @@ impl<ChannelSigner: Sign> Deref for LockedChannelMonitor<'_, ChannelSigner> {
 /// or used independently to monitor channels remotely. See the [module-level documentation] for
 /// details.
 ///
+/// Note that `ChainMonitor` should regularly trigger rebroadcasts/fee bumps of pending claims from
+/// a force-closed channel. This is crucial in preventing certain classes of pinning attacks,
+/// detecting substantial mempool feerate changes between blocks, and ensuring reliability if
+/// broadcasting fails. We recommend invoking this every 30 seconds, or lower if running in an
+/// environment with spotty connections, like on mobile.
+///
 /// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
 /// [module-level documentation]: crate::chain::chainmonitor
-pub struct ChainMonitor<ChannelSigner: Sign, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref>
+/// [`rebroadcast_pending_claims`]: Self::rebroadcast_pending_claims
+pub struct ChainMonitor<ChannelSigner: WriteableEcdsaChannelSigner, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref>
        where C::Target: chain::Filter,
         T::Target: BroadcasterInterface,
         F::Target: FeeEstimator,
@@ -240,9 +290,11 @@ pub struct ChainMonitor<ChannelSigner: Sign, C: Deref, T: Deref, F: Deref, L: De
        pending_monitor_events: Mutex<Vec<(OutPoint, Vec<MonitorEvent>, Option<PublicKey>)>>,
        /// The best block height seen, used as a proxy for the passage of time.
        highest_chain_height: AtomicUsize,
+
+       event_notifier: Notifier,
 }
 
-impl<ChannelSigner: Sign, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref> ChainMonitor<ChannelSigner, C, T, F, L, P>
+impl<ChannelSigner: WriteableEcdsaChannelSigner, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref> ChainMonitor<ChannelSigner, C, T, F, L, P>
 where C::Target: chain::Filter,
            T::Target: BroadcasterInterface,
            F::Target: FeeEstimator,
@@ -264,7 +316,33 @@ where C::Target: chain::Filter,
        where
                FN: Fn(&ChannelMonitor<ChannelSigner>, &TransactionData) -> Vec<TransactionOutputs>
        {
+               let err_str = "ChannelMonitor[Update] persistence failed unrecoverably. This indicates we cannot continue normal operation and must shut down.";
+               let funding_outpoints: HashSet<OutPoint> = HashSet::from_iter(self.monitors.read().unwrap().keys().cloned());
+               for funding_outpoint in funding_outpoints.iter() {
+                       let monitor_lock = self.monitors.read().unwrap();
+                       if let Some(monitor_state) = monitor_lock.get(funding_outpoint) {
+                               if self.update_monitor_with_chain_data(header, best_height, txdata, &process, funding_outpoint, &monitor_state).is_err() {
+                                       // Take the monitors lock for writing so that we poison it and any future
+                                       // operations going forward fail immediately.
+                                       core::mem::drop(monitor_lock);
+                                       let _poison = self.monitors.write().unwrap();
+                                       log_error!(self.logger, "{}", err_str);
+                                       panic!("{}", err_str);
+                               }
+                       }
+               }
+
+               // do some followup cleanup if any funding outpoints were added in between iterations
                let monitor_states = self.monitors.write().unwrap();
+               for (funding_outpoint, monitor_state) in monitor_states.iter() {
+                       if !funding_outpoints.contains(funding_outpoint) {
+                               if self.update_monitor_with_chain_data(header, best_height, txdata, &process, funding_outpoint, &monitor_state).is_err() {
+                                       log_error!(self.logger, "{}", err_str);
+                                       panic!("{}", err_str);
+                               }
+                       }
+               }
+
                if let Some(height) = best_height {
                        // If the best block height is being updated, update highest_chain_height under the
                        // monitors write lock.
@@ -274,57 +352,60 @@ where C::Target: chain::Filter,
                                self.highest_chain_height.store(new_height, Ordering::Release);
                        }
                }
+       }
 
-               for (funding_outpoint, monitor_state) in monitor_states.iter() {
-                       let monitor = &monitor_state.monitor;
-                       let mut txn_outputs;
-                       {
-                               txn_outputs = process(monitor, txdata);
-                               let update_id = MonitorUpdateId {
-                                       contents: UpdateOrigin::ChainSync(self.sync_persistence_id.get_increment()),
-                               };
-                               let mut pending_monitor_updates = monitor_state.pending_monitor_updates.lock().unwrap();
-                               if let Some(height) = best_height {
-                                       if !monitor_state.has_pending_chainsync_updates(&pending_monitor_updates) {
-                                               // If there are not ChainSync persists awaiting completion, go ahead and
-                                               // set last_chain_persist_height here - we wouldn't want the first
-                                               // InProgress to always immediately be considered "overly delayed".
-                                               monitor_state.last_chain_persist_height.store(height as usize, Ordering::Release);
-                                       }
+       fn update_monitor_with_chain_data<FN>(
+               &self, header: &BlockHeader, best_height: Option<u32>, txdata: &TransactionData,
+               process: FN, funding_outpoint: &OutPoint, monitor_state: &MonitorHolder<ChannelSigner>
+       ) -> Result<(), ()> where FN: Fn(&ChannelMonitor<ChannelSigner>, &TransactionData) -> Vec<TransactionOutputs> {
+               let monitor = &monitor_state.monitor;
+               let mut txn_outputs;
+               {
+                       txn_outputs = process(monitor, txdata);
+                       let update_id = MonitorUpdateId {
+                               contents: UpdateOrigin::ChainSync(self.sync_persistence_id.get_increment()),
+                       };
+                       let mut pending_monitor_updates = monitor_state.pending_monitor_updates.lock().unwrap();
+                       if let Some(height) = best_height {
+                               if !monitor_state.has_pending_chainsync_updates(&pending_monitor_updates) {
+                                       // If there are not ChainSync persists awaiting completion, go ahead and
+                                       // set last_chain_persist_height here - we wouldn't want the first
+                                       // InProgress to always immediately be considered "overly delayed".
+                                       monitor_state.last_chain_persist_height.store(height as usize, Ordering::Release);
                                }
+                       }
 
-                               log_trace!(self.logger, "Syncing Channel Monitor for channel {}", log_funding_info!(monitor));
-                               match self.persister.update_persisted_channel(*funding_outpoint, &None, monitor, update_id) {
-                                       ChannelMonitorUpdateStatus::Completed =>
-                                               log_trace!(self.logger, "Finished syncing Channel Monitor for channel {}", log_funding_info!(monitor)),
-                                       ChannelMonitorUpdateStatus::PermanentFailure => {
-                                               monitor_state.channel_perm_failed.store(true, Ordering::Release);
-                                               self.pending_monitor_events.lock().unwrap().push((*funding_outpoint, vec![MonitorEvent::UpdateFailed(*funding_outpoint)], monitor.get_counterparty_node_id()));
-                                       },
-                                       ChannelMonitorUpdateStatus::InProgress => {
-                                               log_debug!(self.logger, "Channel Monitor sync for channel {} in progress, holding events until completion!", log_funding_info!(monitor));
-                                               pending_monitor_updates.push(update_id);
-                                       },
-                               }
+                       log_trace!(self.logger, "Syncing Channel Monitor for channel {}", log_funding_info!(monitor));
+                       match self.persister.update_persisted_channel(*funding_outpoint, None, monitor, update_id) {
+                               ChannelMonitorUpdateStatus::Completed =>
+                                       log_trace!(self.logger, "Finished syncing Channel Monitor for channel {}", log_funding_info!(monitor)),
+                               ChannelMonitorUpdateStatus::InProgress => {
+                                       log_debug!(self.logger, "Channel Monitor sync for channel {} in progress, holding events until completion!", log_funding_info!(monitor));
+                                       pending_monitor_updates.push(update_id);
+                               },
+                               ChannelMonitorUpdateStatus::UnrecoverableError => {
+                                       return Err(());
+                               },
                        }
+               }
 
-                       // Register any new outputs with the chain source for filtering, storing any dependent
-                       // transactions from within the block that previously had not been included in txdata.
-                       if let Some(ref chain_source) = self.chain_source {
-                               let block_hash = header.block_hash();
-                               for (txid, mut outputs) in txn_outputs.drain(..) {
-                                       for (idx, output) in outputs.drain(..) {
-                                               // Register any new outputs with the chain source for filtering
-                                               let output = WatchedOutput {
-                                                       block_hash: Some(block_hash),
-                                                       outpoint: OutPoint { txid, index: idx as u16 },
-                                                       script_pubkey: output.script_pubkey,
-                                               };
-                                               chain_source.register_output(output)
-                                       }
+               // Register any new outputs with the chain source for filtering, storing any dependent
+               // transactions from within the block that previously had not been included in txdata.
+               if let Some(ref chain_source) = self.chain_source {
+                       let block_hash = header.block_hash();
+                       for (txid, mut outputs) in txn_outputs.drain(..) {
+                               for (idx, output) in outputs.drain(..) {
+                                       // Register any new outputs with the chain source for filtering
+                                       let output = WatchedOutput {
+                                               block_hash: Some(block_hash),
+                                               outpoint: OutPoint { txid, index: idx as u16 },
+                                               script_pubkey: output.script_pubkey,
+                                       };
+                                       chain_source.register_output(output)
                                }
                        }
                }
+               Ok(())
        }
 
        /// Creates a new `ChainMonitor` used to watch on-chain activity pertaining to channels.
@@ -345,6 +426,7 @@ where C::Target: chain::Filter,
                        persister,
                        pending_monitor_events: Mutex::new(Vec::new()),
                        highest_chain_height: AtomicUsize::new(0),
+                       event_notifier: Notifier::new(),
                }
        }
 
@@ -395,6 +477,23 @@ where C::Target: chain::Filter,
                self.monitors.read().unwrap().keys().map(|outpoint| *outpoint).collect()
        }
 
+       #[cfg(not(c_bindings))]
+       /// Lists the pending updates for each [`ChannelMonitor`] (by `OutPoint` being monitored).
+       pub fn list_pending_monitor_updates(&self) -> HashMap<OutPoint, Vec<MonitorUpdateId>> {
+               self.monitors.read().unwrap().iter().map(|(outpoint, holder)| {
+                       (*outpoint, holder.pending_monitor_updates.lock().unwrap().clone())
+               }).collect()
+       }
+
+       #[cfg(c_bindings)]
+       /// Lists the pending updates for each [`ChannelMonitor`] (by `OutPoint` being monitored).
+       pub fn list_pending_monitor_updates(&self) -> Vec<(OutPoint, Vec<MonitorUpdateId>)> {
+               self.monitors.read().unwrap().iter().map(|(outpoint, holder)| {
+                       (*outpoint, holder.pending_monitor_updates.lock().unwrap().clone())
+               }).collect()
+       }
+
+
        #[cfg(test)]
        pub fn remove_monitor(&self, funding_txo: &OutPoint) -> ChannelMonitor<ChannelSigner> {
                self.monitors.write().unwrap().remove(funding_txo).unwrap().monitor
@@ -436,9 +535,8 @@ where C::Target: chain::Filter,
                                // `MonitorEvent`s from the monitor back to the `ChannelManager` until they
                                // complete.
                                let monitor_is_pending_updates = monitor_data.has_pending_offchain_updates(&pending_monitor_updates);
-                               if monitor_is_pending_updates || monitor_data.channel_perm_failed.load(Ordering::Acquire) {
-                                       // If there are still monitor updates pending (or an old monitor update
-                                       // finished after a later one perm-failed), we cannot yet construct an
+                               if monitor_is_pending_updates {
+                                       // If there are still monitor updates pending, we cannot yet construct a
                                        // Completed event.
                                        return Ok(());
                                }
@@ -455,6 +553,7 @@ where C::Target: chain::Filter,
                                }
                        },
                }
+               self.event_notifier.notify();
                Ok(())
        }
 
@@ -469,19 +568,65 @@ where C::Target: chain::Filter,
                        funding_txo,
                        monitor_update_id,
                }], counterparty_node_id));
+               self.event_notifier.notify();
        }
 
-       #[cfg(any(test, fuzzing, feature = "_test_utils"))]
+       #[cfg(any(test, feature = "_test_utils"))]
        pub fn get_and_clear_pending_events(&self) -> Vec<events::Event> {
-               use crate::util::events::EventsProvider;
+               use crate::events::EventsProvider;
                let events = core::cell::RefCell::new(Vec::new());
-               let event_handler = |event: &events::Event| events.borrow_mut().push(event.clone());
+               let event_handler = |event: events::Event| events.borrow_mut().push(event);
                self.process_pending_events(&event_handler);
                events.into_inner()
        }
+
+       /// Processes any events asynchronously in the order they were generated since the last call
+       /// using the given event handler.
+       ///
+       /// See the trait-level documentation of [`EventsProvider`] for requirements.
+       ///
+       /// [`EventsProvider`]: crate::events::EventsProvider
+       pub async fn process_pending_events_async<Future: core::future::Future, H: Fn(Event) -> Future>(
+               &self, handler: H
+       ) {
+               // Sadly we can't hold the monitors read lock through an async call. Thus we have to do a
+               // crazy dance to process a monitor's events then only remove them once we've done so.
+               let mons_to_process = self.monitors.read().unwrap().keys().cloned().collect::<Vec<_>>();
+               for funding_txo in mons_to_process {
+                       let mut ev;
+                       super::channelmonitor::process_events_body!(
+                               self.monitors.read().unwrap().get(&funding_txo).map(|m| &m.monitor), ev, handler(ev).await);
+               }
+       }
+
+       /// Gets a [`Future`] that completes when an event is available either via
+       /// [`chain::Watch::release_pending_monitor_events`] or
+       /// [`EventsProvider::process_pending_events`].
+       ///
+       /// Note that callbacks registered on the [`Future`] MUST NOT call back into this
+       /// [`ChainMonitor`] and should instead register actions to be taken later.
+       ///
+       /// [`EventsProvider::process_pending_events`]: crate::events::EventsProvider::process_pending_events
+       pub fn get_update_future(&self) -> Future {
+               self.event_notifier.get_future()
+       }
+
+       /// Triggers rebroadcasts/fee-bumps of pending claims from a force-closed channel. This is
+       /// crucial in preventing certain classes of pinning attacks, detecting substantial mempool
+       /// feerate changes between blocks, and ensuring reliability if broadcasting fails. We recommend
+       /// invoking this every 30 seconds, or lower if running in an environment with spotty
+       /// connections, like on mobile.
+       pub fn rebroadcast_pending_claims(&self) {
+               let monitors = self.monitors.read().unwrap();
+               for (_, monitor_holder) in &*monitors {
+                       monitor_holder.monitor.rebroadcast_pending_claims(
+                               &*self.broadcaster, &*self.fee_estimator, &*self.logger
+                       )
+               }
+       }
 }
 
-impl<ChannelSigner: Sign, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref>
+impl<ChannelSigner: WriteableEcdsaChannelSigner, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref>
 chain::Listen for ChainMonitor<ChannelSigner, C, T, F, L, P>
 where
        C::Target: chain::Filter,
@@ -508,7 +653,7 @@ where
        }
 }
 
-impl<ChannelSigner: Sign, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref>
+impl<ChannelSigner: WriteableEcdsaChannelSigner, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref>
 chain::Confirm for ChainMonitor<ChannelSigner, C, T, F, L, P>
 where
        C::Target: chain::Filter,
@@ -544,7 +689,7 @@ where
                });
        }
 
-       fn get_relevant_txids(&self) -> Vec<Txid> {
+       fn get_relevant_txids(&self) -> Vec<(Txid, Option<BlockHash>)> {
                let mut txids = Vec::new();
                let monitor_states = self.monitors.read().unwrap();
                for monitor_state in monitor_states.values() {
@@ -557,7 +702,7 @@ where
        }
 }
 
-impl<ChannelSigner: Sign, C: Deref , T: Deref , F: Deref , L: Deref , P: Deref >
+impl<ChannelSigner: WriteableEcdsaChannelSigner, C: Deref , T: Deref , F: Deref , L: Deref , P: Deref >
 chain::Watch<ChannelSigner> for ChainMonitor<ChannelSigner, C, T, F, L, P>
 where C::Target: chain::Filter,
            T::Target: BroadcasterInterface,
@@ -565,18 +710,12 @@ where C::Target: chain::Filter,
            L::Target: Logger,
            P::Target: Persist<ChannelSigner>,
 {
-       /// Adds the monitor that watches the channel referred to by the given outpoint.
-       ///
-       /// Calls back to [`chain::Filter`] with the funding transaction and outputs to watch.
-       ///
-       /// Note that we persist the given `ChannelMonitor` while holding the `ChainMonitor`
-       /// monitors lock.
-       fn watch_channel(&self, funding_outpoint: OutPoint, monitor: ChannelMonitor<ChannelSigner>) -> ChannelMonitorUpdateStatus {
+       fn watch_channel(&self, funding_outpoint: OutPoint, monitor: ChannelMonitor<ChannelSigner>) -> Result<ChannelMonitorUpdateStatus, ()> {
                let mut monitors = self.monitors.write().unwrap();
                let entry = match monitors.entry(funding_outpoint) {
                        hash_map::Entry::Occupied(_) => {
                                log_error!(self.logger, "Failed to add new channel data: channel monitor for given outpoint is already present");
-                               return ChannelMonitorUpdateStatus::PermanentFailure
+                               return Err(());
                        },
                        hash_map::Entry::Vacant(e) => e,
                };
@@ -589,13 +728,14 @@ where C::Target: chain::Filter,
                                log_info!(self.logger, "Persistence of new ChannelMonitor for channel {} in progress", log_funding_info!(monitor));
                                pending_monitor_updates.push(update_id);
                        },
-                       ChannelMonitorUpdateStatus::PermanentFailure => {
-                               log_error!(self.logger, "Persistence of new ChannelMonitor for channel {} failed", log_funding_info!(monitor));
-                               return persist_res;
-                       },
                        ChannelMonitorUpdateStatus::Completed => {
                                log_info!(self.logger, "Persistence of new ChannelMonitor for channel {} completed", log_funding_info!(monitor));
-                       }
+                       },
+                       ChannelMonitorUpdateStatus::UnrecoverableError => {
+                               let err_str = "ChannelMonitor[Update] persistence failed unrecoverably. This indicates we cannot continue normal operation and must shut down.";
+                               log_error!(self.logger, "{}", err_str);
+                               panic!("{}", err_str);
+                       },
                }
                if let Some(ref chain_source) = self.chain_source {
                        monitor.load_outputs_to_watch(chain_source);
@@ -603,63 +743,71 @@ where C::Target: chain::Filter,
                entry.insert(MonitorHolder {
                        monitor,
                        pending_monitor_updates: Mutex::new(pending_monitor_updates),
-                       channel_perm_failed: AtomicBool::new(false),
                        last_chain_persist_height: AtomicUsize::new(self.highest_chain_height.load(Ordering::Acquire)),
                });
-               persist_res
+               Ok(persist_res)
        }
 
-       /// Note that we persist the given `ChannelMonitor` update while holding the
-       /// `ChainMonitor` monitors lock.
-       fn update_channel(&self, funding_txo: OutPoint, update: ChannelMonitorUpdate) -> ChannelMonitorUpdateStatus {
+       fn update_channel(&self, funding_txo: OutPoint, update: &ChannelMonitorUpdate) -> ChannelMonitorUpdateStatus {
                // Update the monitor that watches the channel referred to by the given outpoint.
                let monitors = self.monitors.read().unwrap();
-               match monitors.get(&funding_txo) {
+               let ret = match monitors.get(&funding_txo) {
                        None => {
                                log_error!(self.logger, "Failed to update channel monitor: no such monitor registered");
 
                                // We should never ever trigger this from within ChannelManager. Technically a
                                // user could use this object with some proxying in between which makes this
                                // possible, but in tests and fuzzing, this should be a panic.
-                               #[cfg(any(test, fuzzing))]
+                               #[cfg(debug_assertions)]
                                panic!("ChannelManager generated a channel update for a channel that was not yet registered!");
-                               #[cfg(not(any(test, fuzzing)))]
-                               ChannelMonitorUpdateStatus::PermanentFailure
+                               #[cfg(not(debug_assertions))]
+                               ChannelMonitorUpdateStatus::InProgress
                        },
                        Some(monitor_state) => {
                                let monitor = &monitor_state.monitor;
                                log_trace!(self.logger, "Updating ChannelMonitor for channel {}", log_funding_info!(monitor));
-                               let update_res = monitor.update_monitor(&update, &self.broadcaster, &*self.fee_estimator, &self.logger);
-                               if update_res.is_err() {
-                                       log_error!(self.logger, "Failed to update ChannelMonitor for channel {}.", log_funding_info!(monitor));
-                               }
-                               // Even if updating the monitor returns an error, the monitor's state will
-                               // still be changed. So, persist the updated monitor despite the error.
-                               let update_id = MonitorUpdateId::from_monitor_update(&update);
+                               let update_res = monitor.update_monitor(update, &self.broadcaster, &self.fee_estimator, &self.logger);
+
+                               let update_id = MonitorUpdateId::from_monitor_update(update);
                                let mut pending_monitor_updates = monitor_state.pending_monitor_updates.lock().unwrap();
-                               let persist_res = self.persister.update_persisted_channel(funding_txo, &Some(update), monitor, update_id);
+                               let persist_res = if update_res.is_err() {
+                                       // Even if updating the monitor returns an error, the monitor's state will
+                                       // still be changed. Therefore, we should persist the updated monitor despite the error.
+                                       // We don't want to persist a `monitor_update` which results in a failure to apply later
+                                       // while reading `channel_monitor` with updates from storage. Instead, we should persist
+                                       // the entire `channel_monitor` here.
+                                       log_warn!(self.logger, "Failed to update ChannelMonitor for channel {}. Going ahead and persisting the entire ChannelMonitor", log_funding_info!(monitor));
+                                       self.persister.update_persisted_channel(funding_txo, None, monitor, update_id)
+                               } else {
+                                       self.persister.update_persisted_channel(funding_txo, Some(update), monitor, update_id)
+                               };
                                match persist_res {
                                        ChannelMonitorUpdateStatus::InProgress => {
                                                pending_monitor_updates.push(update_id);
                                                log_debug!(self.logger, "Persistence of ChannelMonitorUpdate for channel {} in progress", log_funding_info!(monitor));
                                        },
-                                       ChannelMonitorUpdateStatus::PermanentFailure => {
-                                               monitor_state.channel_perm_failed.store(true, Ordering::Release);
-                                               log_error!(self.logger, "Persistence of ChannelMonitorUpdate for channel {} failed", log_funding_info!(monitor));
-                                       },
                                        ChannelMonitorUpdateStatus::Completed => {
                                                log_debug!(self.logger, "Persistence of ChannelMonitorUpdate for channel {} completed", log_funding_info!(monitor));
                                        },
+                                       ChannelMonitorUpdateStatus::UnrecoverableError => { /* we'll panic in a moment */ },
                                }
                                if update_res.is_err() {
-                                       ChannelMonitorUpdateStatus::PermanentFailure
-                               } else if monitor_state.channel_perm_failed.load(Ordering::Acquire) {
-                                       ChannelMonitorUpdateStatus::PermanentFailure
+                                       ChannelMonitorUpdateStatus::InProgress
                                } else {
                                        persist_res
                                }
                        }
+               };
+               if let ChannelMonitorUpdateStatus::UnrecoverableError = ret {
+                       // Take the monitors lock for writing so that we poison it and any future
+                       // operations going forward fail immediately.
+                       core::mem::drop(monitors);
+                       let _poison = self.monitors.write().unwrap();
+                       let err_str = "ChannelMonitor[Update] persistence failed unrecoverably. This indicates we cannot continue normal operation and must shut down.";
+                       log_error!(self.logger, "{}", err_str);
+                       panic!("{}", err_str);
                }
+               ret
        }
 
        fn release_pending_monitor_events(&self) -> Vec<(OutPoint, Vec<MonitorEvent>, Option<PublicKey>)> {
@@ -670,19 +818,8 @@ where C::Target: chain::Filter,
                                        monitor_state.last_chain_persist_height.load(Ordering::Acquire) + LATENCY_GRACE_PERIOD_BLOCKS as usize
                                                > self.highest_chain_height.load(Ordering::Acquire)
                        {
-                               log_info!(self.logger, "A Channel Monitor sync is still in progress, refusing to provide monitor events!");
+                               log_debug!(self.logger, "A Channel Monitor sync is still in progress, refusing to provide monitor events!");
                        } else {
-                               if monitor_state.channel_perm_failed.load(Ordering::Acquire) {
-                                       // If a `UpdateOrigin::ChainSync` persistence failed with `PermanantFailure`,
-                                       // we don't really know if the latest `ChannelMonitor` state is on disk or not.
-                                       // We're supposed to hold monitor updates until the latest state is on disk to
-                                       // avoid duplicate events, but the user told us persistence is screw-y and may
-                                       // not complete. We can't hold events forever because we may learn some payment
-                                       // preimage, so instead we just log and hope the user complied with the
-                                       // `PermanentFailure` requirements of having at least the local-disk copy
-                                       // updated.
-                                       log_info!(self.logger, "A Channel Monitor sync returned PermanentFailure. Returning monitor events but duplicate events may appear after reload!");
-                               }
                                if is_pending_monitor_update {
                                        log_error!(self.logger, "A ChannelMonitor sync took longer than {} blocks to complete.", LATENCY_GRACE_PERIOD_BLOCKS);
                                        log_error!(self.logger, "   To avoid funds-loss, we are allowing monitor updates to be released.");
@@ -700,37 +837,20 @@ where C::Target: chain::Filter,
        }
 }
 
-impl<ChannelSigner: Sign, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref> events::EventsProvider for ChainMonitor<ChannelSigner, C, T, F, L, P>
+impl<ChannelSigner: WriteableEcdsaChannelSigner, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref> events::EventsProvider for ChainMonitor<ChannelSigner, C, T, F, L, P>
        where C::Target: chain::Filter,
              T::Target: BroadcasterInterface,
              F::Target: FeeEstimator,
              L::Target: Logger,
              P::Target: Persist<ChannelSigner>,
 {
-       #[cfg(not(anchors))]
-       /// Processes [`SpendableOutputs`] events produced from each [`ChannelMonitor`] upon maturity.
-       ///
-       /// An [`EventHandler`] may safely call back to the provider, though this shouldn't be needed in
-       /// order to handle these events.
-       ///
-       /// [`SpendableOutputs`]: events::Event::SpendableOutputs
-       fn process_pending_events<H: Deref>(&self, handler: H) where H::Target: EventHandler {
-               let mut pending_events = Vec::new();
-               for monitor_state in self.monitors.read().unwrap().values() {
-                       pending_events.append(&mut monitor_state.monitor.get_and_clear_pending_events());
-               }
-               for event in pending_events.drain(..) {
-                       handler.handle_event(&event);
-               }
-       }
-       #[cfg(anchors)]
        /// Processes [`SpendableOutputs`] events produced from each [`ChannelMonitor`] upon maturity.
        ///
        /// For channels featuring anchor outputs, this method will also process [`BumpTransaction`]
        /// events produced from each [`ChannelMonitor`] while there is a balance to claim onchain
        /// within each channel. As the confirmation of a commitment transaction may be critical to the
-       /// safety of funds, this method must be invoked frequently, ideally once for every chain tip
-       /// update (block connected or disconnected).
+       /// safety of funds, we recommend invoking this every 30 seconds, or lower if running in an
+       /// environment with spotty connections, like on mobile.
        ///
        /// An [`EventHandler`] may safely call back to the provider, though this shouldn't be needed in
        /// order to handle these events.
@@ -738,30 +858,24 @@ impl<ChannelSigner: Sign, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref> even
        /// [`SpendableOutputs`]: events::Event::SpendableOutputs
        /// [`BumpTransaction`]: events::Event::BumpTransaction
        fn process_pending_events<H: Deref>(&self, handler: H) where H::Target: EventHandler {
-               let mut pending_events = Vec::new();
                for monitor_state in self.monitors.read().unwrap().values() {
-                       pending_events.append(&mut monitor_state.monitor.get_and_clear_pending_events());
-               }
-               for event in pending_events.drain(..) {
-                       handler.handle_event(&event);
+                       monitor_state.monitor.process_pending_events(&handler);
                }
        }
 }
 
 #[cfg(test)]
 mod tests {
-       use bitcoin::{BlockHeader, TxMerkleNode};
-       use bitcoin::hashes::Hash;
-       use crate::{check_added_monitors, check_closed_broadcast, check_closed_event};
-       use crate::{expect_payment_sent, expect_payment_claimed, expect_payment_sent_without_paths, expect_payment_path_successful, get_event_msg};
+       use crate::check_added_monitors;
+       use crate::{expect_payment_claimed, expect_payment_path_successful, get_event_msg};
        use crate::{get_htlc_update_msgs, get_local_commitment_txn, get_revoke_commit_msgs, get_route_and_payment_hash, unwrap_send_err};
        use crate::chain::{ChannelMonitorUpdateStatus, Confirm, Watch};
        use crate::chain::channelmonitor::LATENCY_GRACE_PERIOD_BLOCKS;
-       use crate::ln::channelmanager::{self, PaymentSendFailure, PaymentId};
+       use crate::events::{Event, MessageSendEvent, MessageSendEventsProvider};
+       use crate::ln::channelmanager::{PaymentSendFailure, PaymentId, RecipientOnionFields};
        use crate::ln::functional_test_utils::*;
        use crate::ln::msgs::ChannelMessageHandler;
        use crate::util::errors::APIError;
-       use crate::util::events::{ClosureReason, MessageSendEvent, MessageSendEventsProvider};
 
        #[test]
        fn test_async_ooo_offchain_updates() {
@@ -772,23 +886,20 @@ mod tests {
                let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
                let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
                let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
-               create_announced_chan_between_nodes(&nodes, 0, 1, channelmanager::provided_init_features(), channelmanager::provided_init_features());
+               create_announced_chan_between_nodes(&nodes, 0, 1);
 
                // Route two payments to be claimed at the same time.
-               let (payment_preimage_1, payment_hash_1, _) = route_payment(&nodes[0], &[&nodes[1]], 1_000_000);
-               let (payment_preimage_2, payment_hash_2, _) = route_payment(&nodes[0], &[&nodes[1]], 1_000_000);
+               let (payment_preimage_1, payment_hash_1, ..) = route_payment(&nodes[0], &[&nodes[1]], 1_000_000);
+               let (payment_preimage_2, payment_hash_2, ..) = route_payment(&nodes[0], &[&nodes[1]], 1_000_000);
 
                chanmon_cfgs[1].persister.offchain_monitor_updates.lock().unwrap().clear();
                chanmon_cfgs[1].persister.set_update_ret(ChannelMonitorUpdateStatus::InProgress);
+               chanmon_cfgs[1].persister.set_update_ret(ChannelMonitorUpdateStatus::InProgress);
 
                nodes[1].node.claim_funds(payment_preimage_1);
                check_added_monitors!(nodes[1], 1);
-               expect_payment_claimed!(nodes[1], payment_hash_1, 1_000_000);
                nodes[1].node.claim_funds(payment_preimage_2);
                check_added_monitors!(nodes[1], 1);
-               expect_payment_claimed!(nodes[1], payment_hash_2, 1_000_000);
-
-               chanmon_cfgs[1].persister.set_update_ret(ChannelMonitorUpdateStatus::Completed);
 
                let persistences = chanmon_cfgs[1].persister.offchain_monitor_updates.lock().unwrap().clone();
                assert_eq!(persistences.len(), 1);
@@ -798,17 +909,48 @@ mod tests {
                // Note that updates is a HashMap so the ordering here is actually random. This shouldn't
                // fail either way but if it fails intermittently it's depending on the ordering of updates.
                let mut update_iter = updates.iter();
-               nodes[1].chain_monitor.chain_monitor.channel_monitor_updated(*funding_txo, update_iter.next().unwrap().clone()).unwrap();
+               let next_update = update_iter.next().unwrap().clone();
+               // Should contain next_update when pending updates listed.
+               #[cfg(not(c_bindings))]
+               assert!(nodes[1].chain_monitor.chain_monitor.list_pending_monitor_updates().get(funding_txo)
+                       .unwrap().contains(&next_update));
+               #[cfg(c_bindings)]
+               assert!(nodes[1].chain_monitor.chain_monitor.list_pending_monitor_updates().iter()
+                       .find(|(txo, _)| txo == funding_txo).unwrap().1.contains(&next_update));
+               nodes[1].chain_monitor.chain_monitor.channel_monitor_updated(*funding_txo, next_update.clone()).unwrap();
+               // Should not contain the previously pending next_update when pending updates listed.
+               #[cfg(not(c_bindings))]
+               assert!(!nodes[1].chain_monitor.chain_monitor.list_pending_monitor_updates().get(funding_txo)
+                       .unwrap().contains(&next_update));
+               #[cfg(c_bindings)]
+               assert!(!nodes[1].chain_monitor.chain_monitor.list_pending_monitor_updates().iter()
+                       .find(|(txo, _)| txo == funding_txo).unwrap().1.contains(&next_update));
                assert!(nodes[1].chain_monitor.release_pending_monitor_events().is_empty());
                assert!(nodes[1].node.get_and_clear_pending_msg_events().is_empty());
+               assert!(nodes[1].node.get_and_clear_pending_events().is_empty());
                nodes[1].chain_monitor.chain_monitor.channel_monitor_updated(*funding_txo, update_iter.next().unwrap().clone()).unwrap();
 
+               let claim_events = nodes[1].node.get_and_clear_pending_events();
+               assert_eq!(claim_events.len(), 2);
+               match claim_events[0] {
+                       Event::PaymentClaimed { ref payment_hash, amount_msat: 1_000_000, .. } => {
+                               assert_eq!(payment_hash_1, *payment_hash);
+                       },
+                       _ => panic!("Unexpected event"),
+               }
+               match claim_events[1] {
+                       Event::PaymentClaimed { ref payment_hash, amount_msat: 1_000_000, .. } => {
+                               assert_eq!(payment_hash_2, *payment_hash);
+                       },
+                       _ => panic!("Unexpected event"),
+               }
+
                // Now manually walk the commitment signed dance - because we claimed two payments
                // back-to-back it doesn't fit into the neat walk commitment_signed_dance does.
 
                let updates = get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id());
                nodes[0].node.handle_update_fulfill_htlc(&nodes[1].node.get_our_node_id(), &updates.update_fulfill_htlcs[0]);
-               expect_payment_sent_without_paths!(nodes[0], payment_preimage_1);
+               expect_payment_sent(&nodes[0], payment_preimage_1, None, false, false);
                nodes[0].node.handle_commitment_signed(&nodes[1].node.get_our_node_id(), &updates.commitment_signed);
                check_added_monitors!(nodes[0], 1);
                let (as_first_raa, as_first_update) = get_revoke_commit_msgs!(nodes[0], nodes[1].node.get_our_node_id());
@@ -821,7 +963,7 @@ mod tests {
                let bs_first_raa = get_event_msg!(nodes[1], MessageSendEvent::SendRevokeAndACK, nodes[0].node.get_our_node_id());
 
                nodes[0].node.handle_update_fulfill_htlc(&nodes[1].node.get_our_node_id(), &bs_second_updates.update_fulfill_htlcs[0]);
-               expect_payment_sent_without_paths!(nodes[0], payment_preimage_2);
+               expect_payment_sent(&nodes[0], payment_preimage_2, None, false, false);
                nodes[0].node.handle_commitment_signed(&nodes[1].node.get_our_node_id(), &bs_second_updates.commitment_signed);
                check_added_monitors!(nodes[0], 1);
                nodes[0].node.handle_revoke_and_ack(&nodes[1].node.get_our_node_id(), &bs_first_raa);
@@ -848,15 +990,14 @@ mod tests {
                let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
                let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
                let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
-               let channel = create_announced_chan_between_nodes(
-                       &nodes, 0, 1, channelmanager::provided_init_features(), channelmanager::provided_init_features());
+               let channel = create_announced_chan_between_nodes(&nodes, 0, 1);
 
                // Get a route for later and rebalance the channel somewhat
                send_payment(&nodes[0], &[&nodes[1]], 10_000_000);
                let (route, second_payment_hash, _, second_payment_secret) = get_route_and_payment_hash!(nodes[0], nodes[1], 100_000);
 
                // First route a payment that we will claim on chain and give the recipient the preimage.
-               let (payment_preimage, payment_hash, _) = route_payment(&nodes[0], &[&nodes[1]], 1_000_000);
+               let (payment_preimage, payment_hash, ..) = route_payment(&nodes[0], &[&nodes[1]], 1_000_000);
                nodes[1].node.claim_funds(payment_preimage);
                expect_payment_claimed!(nodes[1], payment_hash, 1_000_000);
                nodes[1].node.get_and_clear_pending_msg_events();
@@ -870,10 +1011,7 @@ mod tests {
 
                // Connect B's commitment transaction, but only to the ChainMonitor/ChannelMonitor. The
                // channel is now closed, but the ChannelManager doesn't know that yet.
-               let new_header = BlockHeader {
-                       version: 2, time: 0, bits: 0, nonce: 0,
-                       prev_blockhash: nodes[0].best_block_info().0,
-                       merkle_root: TxMerkleNode::all_zeros() };
+               let new_header = create_dummy_header(nodes[0].best_block_info().0, 0);
                nodes[0].chain_monitor.chain_monitor.transactions_confirmed(&new_header,
                        &[(0, &remote_txn[0]), (1, &remote_txn[1])], nodes[0].best_block_info().1 + 1);
                assert!(nodes[0].chain_monitor.release_pending_monitor_events().is_empty());
@@ -883,12 +1021,10 @@ mod tests {
                // If the ChannelManager tries to update the channel, however, the ChainMonitor will pass
                // the update through to the ChannelMonitor which will refuse it (as the channel is closed).
                chanmon_cfgs[0].persister.set_update_ret(ChannelMonitorUpdateStatus::Completed);
-               unwrap_send_err!(nodes[0].node.send_payment(&route, second_payment_hash, &Some(second_payment_secret), PaymentId(second_payment_hash.0)),
-                       true, APIError::ChannelUnavailable { ref err },
-                       assert!(err.contains("ChannelMonitor storage failure")));
-               check_added_monitors!(nodes[0], 2); // After the failure we generate a close-channel monitor update
-               check_closed_broadcast!(nodes[0], true);
-               check_closed_event!(nodes[0], 1, ClosureReason::ProcessingError { err: "ChannelMonitor storage failure".to_string() });
+               unwrap_send_err!(nodes[0].node.send_payment_with_route(&route, second_payment_hash,
+                               RecipientOnionFields::secret_only(second_payment_secret), PaymentId(second_payment_hash.0)
+                       ), false, APIError::MonitorUpdateInProgress, {});
+               check_added_monitors!(nodes[0], 1);
 
                // However, as the ChainMonitor is still waiting for the original persistence to complete,
                // it won't yet release the MonitorEvents.
@@ -896,10 +1032,7 @@ mod tests {
 
                if block_timeout {
                        // After three blocks, pending MontiorEvents should be released either way.
-                       let latest_header = BlockHeader {
-                               version: 2, time: 0, bits: 0, nonce: 0,
-                               prev_blockhash: nodes[0].best_block_info().0,
-                               merkle_root: TxMerkleNode::all_zeros() };
+                       let latest_header = create_dummy_header(nodes[0].best_block_info().0, 0);
                        nodes[0].chain_monitor.chain_monitor.best_block_updated(&latest_header, nodes[0].best_block_info().1 + LATENCY_GRACE_PERIOD_BLOCKS);
                } else {
                        let persistences = chanmon_cfgs[0].persister.chain_sync_monitor_persistences.lock().unwrap().clone();
@@ -910,7 +1043,7 @@ mod tests {
                        }
                }
 
-               expect_payment_sent!(nodes[0], payment_preimage);
+               expect_payment_sent(&nodes[0], payment_preimage, None, true, false);
        }
 
        #[test]
@@ -920,25 +1053,24 @@ mod tests {
        }
 
        #[test]
-       fn update_during_chainsync_fails_channel() {
+       #[cfg(feature = "std")]
+       fn update_during_chainsync_poisons_channel() {
                let chanmon_cfgs = create_chanmon_cfgs(2);
                let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
                let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
                let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
-               create_announced_chan_between_nodes(&nodes, 0, 1, channelmanager::provided_init_features(), channelmanager::provided_init_features());
+               create_announced_chan_between_nodes(&nodes, 0, 1);
 
                chanmon_cfgs[0].persister.chain_sync_monitor_persistences.lock().unwrap().clear();
-               chanmon_cfgs[0].persister.set_update_ret(ChannelMonitorUpdateStatus::PermanentFailure);
-
-               connect_blocks(&nodes[0], 1);
-               // Before processing events, the ChannelManager will still think the Channel is open and
-               // there won't be any ChannelMonitorUpdates
-               assert_eq!(nodes[0].node.list_channels().len(), 1);
-               check_added_monitors!(nodes[0], 0);
-               // ... however once we get events once, the channel will close, creating a channel-closed
-               // ChannelMonitorUpdate.
-               check_closed_broadcast!(nodes[0], true);
-               check_closed_event!(nodes[0], 1, ClosureReason::ProcessingError { err: "Failed to persist ChannelMonitor update during chain sync".to_string() });
-               check_added_monitors!(nodes[0], 1);
+               chanmon_cfgs[0].persister.set_update_ret(ChannelMonitorUpdateStatus::UnrecoverableError);
+
+               assert!(std::panic::catch_unwind(|| {
+                       // Returning an UnrecoverableError should always panic immediately
+                       connect_blocks(&nodes[0], 1);
+               }).is_err());
+               assert!(std::panic::catch_unwind(|| {
+                       // ...and also poison our locks causing later use to panic as well
+                       core::mem::drop(nodes);
+               }).is_err());
        }
 }