Track actions to execute after a `ChannelMonitor` is updated
[rust-lightning] / lightning / src / ln / channelmanager.rs
index 720f6e42992db450fb02baf5b25c7b9227e9850c..9b277ff1e4691cd462d75f2b9f0abc97751e59d1 100644 (file)
@@ -65,12 +65,14 @@ use crate::util::ser::{BigSize, FixedLengthReader, Readable, ReadableArgs, Maybe
 use crate::util::logger::{Level, Logger};
 use crate::util::errors::APIError;
 
+use alloc::collections::BTreeMap;
+
 use crate::io;
 use crate::prelude::*;
 use core::{cmp, mem};
 use core::cell::RefCell;
 use crate::io::Read;
-use crate::sync::{Arc, Mutex, RwLock, RwLockReadGuard, FairRwLock};
+use crate::sync::{Arc, Mutex, RwLock, RwLockReadGuard, FairRwLock, LockTestExt, LockHeldState};
 use core::sync::atomic::{AtomicUsize, Ordering};
 use core::time::Duration;
 use core::ops::Deref;
@@ -474,6 +476,11 @@ pub(crate) enum MonitorUpdateCompletionAction {
        EmitEvent { event: events::Event },
 }
 
+impl_writeable_tlv_based_enum_upgradable!(MonitorUpdateCompletionAction,
+       (0, PaymentClaimed) => { (0, payment_hash, required) },
+       (2, EmitEvent) => { (0, event, ignorable) },
+);
+
 /// State we hold per-peer.
 pub(super) struct PeerState<Signer: ChannelSigner> {
        /// `temporary_channel_id` or `channel_id` -> `channel`.
@@ -487,12 +494,39 @@ pub(super) struct PeerState<Signer: ChannelSigner> {
        /// Messages to send to the peer - pushed to in the same lock that they are generated in (except
        /// for broadcast messages, where ordering isn't as strict).
        pub(super) pending_msg_events: Vec<MessageSendEvent>,
+       /// Map from a specific channel to some action(s) that should be taken when all pending
+       /// [`ChannelMonitorUpdate`]s for the channel complete updating.
+       ///
+       /// Note that because we generally only have one entry here a HashMap is pretty overkill. A
+       /// BTreeMap currently stores more than ten elements per leaf node, so even up to a few
+       /// channels with a peer this will just be one allocation and will amount to a linear list of
+       /// channels to walk, avoiding the whole hashing rigmarole.
+       ///
+       /// Note that the channel may no longer exist. For example, if a channel was closed but we
+       /// later needed to claim an HTLC which is pending on-chain, we may generate a monitor update
+       /// for a missing channel. While a malicious peer could construct a second channel with the
+       /// same `temporary_channel_id` (or final `channel_id` in the case of 0conf channels or prior
+       /// to funding appearing on-chain), the downstream `ChannelMonitor` set is required to ensure
+       /// duplicates do not occur, so such channels should fail without a monitor update completing.
+       monitor_update_blocked_actions: BTreeMap<[u8; 32], Vec<MonitorUpdateCompletionAction>>,
        /// The peer is currently connected (i.e. we've seen a
        /// [`ChannelMessageHandler::peer_connected`] and no corresponding
        /// [`ChannelMessageHandler::peer_disconnected`].
        is_connected: bool,
 }
 
+impl <Signer: ChannelSigner> PeerState<Signer> {
+       /// Indicates that a peer meets the criteria where we're ok to remove it from our storage.
+       /// If true is passed for `require_disconnected`, the function will return false if we haven't
+       /// disconnected from the node already, ie. `PeerState::is_connected` is set to `true`.
+       fn ok_to_remove(&self, require_disconnected: bool) -> bool {
+               if require_disconnected && self.is_connected {
+                       return false
+               }
+               self.channel_by_id.is_empty() && self.monitor_update_blocked_actions.is_empty()
+       }
+}
+
 /// Stores a PaymentSecret and any other data we may need to validate an inbound payment is
 /// actually ours and not some duplicate HTLC sent to us by a node along the route.
 ///
@@ -1178,9 +1212,9 @@ pub enum RecentPaymentDetails {
                /// made before LDK version 0.0.104.
                payment_hash: Option<PaymentHash>,
        },
-       /// After a payment is explicitly abandoned by calling [`ChannelManager::abandon_payment`], it
-       /// is marked as abandoned until an [`Event::PaymentFailed`] is generated. A payment could also
-       /// be marked as abandoned if pathfinding fails repeatedly or retries have been exhausted.
+       /// After a payment's retries are exhausted per the provided [`Retry`], or it is explicitly
+       /// abandoned via [`ChannelManager::abandon_payment`], it is marked as abandoned until all
+       /// pending HTLCs for this payment resolve and an [`Event::PaymentFailed`] is generated.
        Abandoned {
                /// Hash of the payment that we have given up trying to send.
                payment_hash: PaymentHash,
@@ -1206,13 +1240,10 @@ macro_rules! handle_error {
                match $internal {
                        Ok(msg) => Ok(msg),
                        Err(MsgHandleErrInternal { err, chan_id, shutdown_finish }) => {
-                               #[cfg(any(feature = "_test_utils", test))]
-                               {
-                                       // In testing, ensure there are no deadlocks where the lock is already held upon
-                                       // entering the macro.
-                                       debug_assert!($self.pending_events.try_lock().is_ok());
-                                       debug_assert!($self.per_peer_state.try_write().is_ok());
-                               }
+                               // In testing, ensure there are no deadlocks where the lock is already held upon
+                               // entering the macro.
+                               debug_assert_ne!($self.pending_events.held_by_thread(), LockHeldState::HeldByThread);
+                               debug_assert_ne!($self.per_peer_state.held_by_thread(), LockHeldState::HeldByThread);
 
                                let mut msg_events = Vec::with_capacity(2);
 
@@ -1246,26 +1277,6 @@ macro_rules! handle_error {
                                                let mut peer_state = peer_state_mutex.lock().unwrap();
                                                peer_state.pending_msg_events.append(&mut msg_events);
                                        }
-                                       #[cfg(any(feature = "_test_utils", test))]
-                                       {
-                                               if per_peer_state.get(&$counterparty_node_id).is_none() {
-                                                       // This shouldn't occur in tests unless an unknown counterparty_node_id
-                                                       // has been passed to our message handling functions.
-                                                       let expected_error_str = format!("Can't find a peer matching the passed counterparty node_id {}", $counterparty_node_id);
-                                                       match err.action {
-                                                               msgs::ErrorAction::SendErrorMessage {
-                                                                       msg: msgs::ErrorMessage { ref channel_id, ref data }
-                                                               }
-                                                               => {
-                                                                       assert_eq!(*data, expected_error_str);
-                                                                       if let Some((err_channel_id, _user_channel_id)) = chan_id {
-                                                                               debug_assert_eq!(*channel_id, err_channel_id);
-                                                                       }
-                                                               }
-                                                               _ => debug_assert!(false, "Unexpected event"),
-                                                       }
-                                               }
-                                       }
                                }
 
                                // Return error in case higher-API need one
@@ -1636,14 +1647,13 @@ where
        }
 
        fn list_channels_with_filter<Fn: FnMut(&(&[u8; 32], &Channel<<SP::Target as SignerProvider>::Signer>)) -> bool + Copy>(&self, f: Fn) -> Vec<ChannelDetails> {
-               let mut res = Vec::new();
                // Allocate our best estimate of the number of channels we have in the `res`
                // Vec. Sadly the `short_to_chan_info` map doesn't cover channels without
                // a scid or a scid alias, and the `id_to_peer` shouldn't be used outside
                // of the ChannelMonitor handling. Therefore reallocations may still occur, but is
                // unlikely as the `short_to_chan_info` map often contains 2 entries for
                // the same channel.
-               res.reserve(self.short_to_chan_info.read().unwrap().len());
+               let mut res = Vec::with_capacity(self.short_to_chan_info.read().unwrap().len());
                {
                        let best_block_height = self.best_block.read().unwrap().height();
                        let per_peer_state = self.per_peer_state.read().unwrap();
@@ -1727,7 +1737,7 @@ where
        ///
        /// This can be useful for payments that may have been prepared, but ultimately not sent, as a
        /// result of a crash. If such a payment exists, is not listed here, and an
-       /// [`Event::PaymentSent`] has not been received, you may consider retrying the payment.
+       /// [`Event::PaymentSent`] has not been received, you may consider resending the payment.
        ///
        /// [`Event::PaymentSent`]: events::Event::PaymentSent
        pub fn list_recent_payments(&self) -> Vec<RecentPaymentDetails> {
@@ -1774,7 +1784,7 @@ where
                        let per_peer_state = self.per_peer_state.read().unwrap();
 
                        let peer_state_mutex = per_peer_state.get(counterparty_node_id)
-                               .ok_or_else(|| APIError::APIMisuseError{ err: format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id) })?;
+                               .ok_or_else(|| APIError::ChannelUnavailable { err: format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id) })?;
 
                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
@@ -1893,7 +1903,7 @@ where
        -> Result<PublicKey, APIError> {
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(peer_node_id)
-                       .ok_or_else(|| APIError::APIMisuseError{ err: format!("Can't find a peer matching the passed counterparty node_id {}", peer_node_id) })?;
+                       .ok_or_else(|| APIError::ChannelUnavailable { err: format!("Can't find a peer matching the passed counterparty node_id {}", peer_node_id) })?;
                let mut chan = {
                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
@@ -2402,10 +2412,10 @@ where
                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        if let hash_map::Entry::Occupied(mut chan) = peer_state.channel_by_id.entry(id) {
+                               if !chan.get().is_live() {
+                                       return Err(APIError::ChannelUnavailable{err: "Peer for first hop currently disconnected".to_owned()});
+                               }
                                match {
-                                       if !chan.get().is_live() {
-                                               return Err(APIError::ChannelUnavailable{err: "Peer for first hop currently disconnected/pending monitor update!".to_owned()});
-                                       }
                                        break_chan_entry!(self, chan.get_mut().send_htlc_and_commit(
                                                htlc_msat, payment_hash.clone(), htlc_cltv, HTLCSource::OutboundRoute {
                                                        path: path.clone(),
@@ -2484,8 +2494,8 @@ where
        /// If a pending payment is currently in-flight with the same [`PaymentId`] provided, this
        /// method will error with an [`APIError::InvalidRoute`]. Note, however, that once a payment
        /// is no longer pending (either via [`ChannelManager::abandon_payment`], or handling of an
-       /// [`Event::PaymentSent`]) LDK will not stop you from sending a second payment with the same
-       /// [`PaymentId`].
+       /// [`Event::PaymentSent`] or [`Event::PaymentFailed`]) LDK will not stop you from sending a
+       /// second payment with the same [`PaymentId`].
        ///
        /// Thus, in order to ensure duplicate payments are not sent, you should implement your own
        /// tracking of payments, including state to indicate once a payment has completed. Because you
@@ -2530,6 +2540,7 @@ where
        /// [`Route`], we assume the invoice had the basic_mpp feature set.
        ///
        /// [`Event::PaymentSent`]: events::Event::PaymentSent
+       /// [`Event::PaymentFailed`]: events::Event::PaymentFailed
        /// [`PeerManager::process_events`]: crate::ln::peer_handler::PeerManager::process_events
        /// [`ChannelMonitorUpdateStatus::InProgress`]: crate::chain::ChannelMonitorUpdateStatus::InProgress
        pub fn send_payment(&self, route: &Route, payment_hash: PaymentHash, payment_secret: &Option<PaymentSecret>, payment_id: PaymentId) -> Result<(), PaymentSendFailure> {
@@ -2546,7 +2557,7 @@ where
                let best_block_height = self.best_block.read().unwrap().height();
                self.pending_outbound_payments
                        .send_payment(payment_hash, payment_secret, payment_id, retry_strategy, route_params,
-                               &self.router, self.list_usable_channels(), self.compute_inflight_htlcs(),
+                               &self.router, self.list_usable_channels(), || self.compute_inflight_htlcs(),
                                &self.entropy_source, &self.node_signer, best_block_height, &self.logger,
                                |path, payment_params, payment_hash, payment_secret, total_value, cur_height, payment_id, keysend_preimage, session_priv|
                                self.send_payment_along_path(path, payment_params, payment_hash, payment_secret, total_value, cur_height, payment_id, keysend_preimage, session_priv))
@@ -2567,48 +2578,25 @@ where
        }
 
 
-       /// Retries a payment along the given [`Route`].
+       /// Signals that no further retries for the given payment should occur. Useful if you have a
+       /// pending outbound payment with retries remaining, but wish to stop retrying the payment before
+       /// retries are exhausted.
        ///
-       /// Errors returned are a superset of those returned from [`send_payment`], so see
-       /// [`send_payment`] documentation for more details on errors. This method will also error if the
-       /// retry amount puts the payment more than 10% over the payment's total amount, if the payment
-       /// for the given `payment_id` cannot be found (likely due to timeout or success), or if
-       /// further retries have been disabled with [`abandon_payment`].
-       ///
-       /// [`send_payment`]: [`ChannelManager::send_payment`]
-       /// [`abandon_payment`]: [`ChannelManager::abandon_payment`]
-       pub fn retry_payment(&self, route: &Route, payment_id: PaymentId) -> Result<(), PaymentSendFailure> {
-               let best_block_height = self.best_block.read().unwrap().height();
-               self.pending_outbound_payments.retry_payment_with_route(route, payment_id, &self.entropy_source, &self.node_signer, best_block_height,
-                       |path, payment_params, payment_hash, payment_secret, total_value, cur_height, payment_id, keysend_preimage, session_priv|
-                       self.send_payment_along_path(path, payment_params, payment_hash, payment_secret, total_value, cur_height, payment_id, keysend_preimage, session_priv))
-       }
-
-       /// Signals that no further retries for the given payment will occur.
-       ///
-       /// After this method returns, no future calls to [`retry_payment`] for the given `payment_id`
-       /// are allowed. If no [`Event::PaymentFailed`] event had been generated before, one will be
-       /// generated as soon as there are no remaining pending HTLCs for this payment.
+       /// If no [`Event::PaymentFailed`] event had been generated before, one will be generated as soon
+       /// as there are no remaining pending HTLCs for this payment.
        ///
        /// Note that calling this method does *not* prevent a payment from succeeding. You must still
        /// wait until you receive either a [`Event::PaymentFailed`] or [`Event::PaymentSent`] event to
        /// determine the ultimate status of a payment.
        ///
        /// If an [`Event::PaymentFailed`] event is generated and we restart without this
-       /// [`ChannelManager`] having been persisted, the payment may still be in the pending state
-       /// upon restart. This allows further calls to [`retry_payment`] (and requiring a second call
-       /// to [`abandon_payment`] to mark the payment as failed again). Otherwise, future calls to
-       /// [`retry_payment`] will fail with [`PaymentSendFailure::ParameterError`].
+       /// [`ChannelManager`] having been persisted, another [`Event::PaymentFailed`] may be generated.
        ///
-       /// [`abandon_payment`]: Self::abandon_payment
-       /// [`retry_payment`]: Self::retry_payment
        /// [`Event::PaymentFailed`]: events::Event::PaymentFailed
        /// [`Event::PaymentSent`]: events::Event::PaymentSent
        pub fn abandon_payment(&self, payment_id: PaymentId) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);
-               if let Some(payment_failed_ev) = self.pending_outbound_payments.abandon_payment(payment_id) {
-                       self.pending_events.lock().unwrap().push(payment_failed_ev);
-               }
+               self.pending_outbound_payments.abandon_payment(payment_id, &self.pending_events);
        }
 
        /// Send a spontaneous payment, which is a payment that does not require the recipient to have
@@ -2637,11 +2625,16 @@ where
 
        /// Similar to [`ChannelManager::send_spontaneous_payment`], but will automatically find a route
        /// based on `route_params` and retry failed payment paths based on `retry_strategy`.
+       ///
+       /// See [`PaymentParameters::for_keysend`] for help in constructing `route_params` for spontaneous
+       /// payments.
+       ///
+       /// [`PaymentParameters::for_keysend`]: crate::routing::router::PaymentParameters::for_keysend
        pub fn send_spontaneous_payment_with_retry(&self, payment_preimage: Option<PaymentPreimage>, payment_id: PaymentId, route_params: RouteParameters, retry_strategy: Retry) -> Result<PaymentHash, PaymentSendFailure> {
                let best_block_height = self.best_block.read().unwrap().height();
                self.pending_outbound_payments.send_spontaneous_payment(payment_preimage, payment_id,
                        retry_strategy, route_params, &self.router, self.list_usable_channels(),
-                       self.compute_inflight_htlcs(),  &self.entropy_source, &self.node_signer, best_block_height,
+                       || self.compute_inflight_htlcs(),  &self.entropy_source, &self.node_signer, best_block_height,
                        &self.logger,
                        |path, payment_params, payment_hash, payment_secret, total_value, cur_height, payment_id, keysend_preimage, session_priv|
                        self.send_payment_along_path(path, payment_params, payment_hash, payment_secret, total_value, cur_height, payment_id, keysend_preimage, session_priv))
@@ -2671,7 +2664,7 @@ where
        ) -> Result<(), APIError> {
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(counterparty_node_id)
-                       .ok_or_else(|| APIError::ChannelUnavailable{ err: format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id) })?;
+                       .ok_or_else(|| APIError::ChannelUnavailable { err: format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id) })?;
 
                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
@@ -2840,7 +2833,7 @@ where
                );
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(counterparty_node_id)
-                       .ok_or_else(|| APIError::APIMisuseError{ err: format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id) })?;
+                       .ok_or_else(|| APIError::ChannelUnavailable { err: format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id) })?;
                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                for channel_id in channel_ids {
@@ -2895,7 +2888,7 @@ where
                let next_hop_scid = {
                        let peer_state_lock = self.per_peer_state.read().unwrap();
                        let peer_state_mutex = peer_state_lock.get(&next_node_id)
-                               .ok_or_else(|| APIError::APIMisuseError{ err: format!("Can't find a peer matching the passed counterparty node_id {}", next_node_id) })?;
+                               .ok_or_else(|| APIError::ChannelUnavailable { err: format!("Can't find a peer matching the passed counterparty node_id {}", next_node_id) })?;
                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        match peer_state.channel_by_id.get(next_hop_channel_id) {
@@ -3376,7 +3369,8 @@ where
 
                let best_block_height = self.best_block.read().unwrap().height();
                self.pending_outbound_payments.check_retry_payments(&self.router, || self.list_usable_channels(),
-                       || self.compute_inflight_htlcs(), &self.entropy_source, &self.node_signer, best_block_height, &self.logger,
+                       || self.compute_inflight_htlcs(), &self.entropy_source, &self.node_signer, best_block_height,
+                       &self.pending_events, &self.logger,
                        |path, payment_params, payment_hash, payment_secret, total_value, cur_height, payment_id, keysend_preimage, session_priv|
                        self.send_payment_along_path(path, payment_params, payment_hash, payment_secret, total_value, cur_height, payment_id, keysend_preimage, session_priv));
 
@@ -3421,38 +3415,6 @@ where
                true
        }
 
-       /// When a peer disconnects but still has channels, the peer's `peer_state` entry in the
-       /// `per_peer_state` is not removed by the `peer_disconnected` function. If the channels of
-       /// to that peer is later closed while still being disconnected (i.e. force closed), we
-       /// therefore need to remove the peer from `peer_state` separately.
-       /// To avoid having to take the `per_peer_state` `write` lock once the channels are closed, we
-       /// instead remove such peers awaiting removal through this function, which is called on a
-       /// timer through `timer_tick_occurred`, passing the peers disconnected peers with no channels,
-       /// to limit the negative effects on parallelism as much as possible.
-       ///
-       /// Must be called without the `per_peer_state` lock acquired.
-       fn remove_peers_awaiting_removal(&self, pending_peers_awaiting_removal: HashSet<PublicKey>) {
-               if pending_peers_awaiting_removal.len() > 0 {
-                       let mut per_peer_state = self.per_peer_state.write().unwrap();
-                       for counterparty_node_id in pending_peers_awaiting_removal {
-                               match per_peer_state.entry(counterparty_node_id) {
-                                       hash_map::Entry::Occupied(entry) => {
-                                               // Remove the entry if the peer is still disconnected and we still
-                                               // have no channels to the peer.
-                                               let remove_entry = {
-                                                       let peer_state = entry.get().lock().unwrap();
-                                                       !peer_state.is_connected && peer_state.channel_by_id.len() == 0
-                                               };
-                                               if remove_entry {
-                                                       entry.remove_entry();
-                                               }
-                                       },
-                                       hash_map::Entry::Vacant(_) => { /* The PeerState has already been removed */ }
-                               }
-                       }
-               }
-       }
-
        #[cfg(any(test, feature = "_test_utils"))]
        /// Process background events, for functional testing
        pub fn test_process_background_events(&self) {
@@ -3526,7 +3488,7 @@ where
 
                        let mut handle_errors: Vec<(Result<(), _>, _)> = Vec::new();
                        let mut timed_out_mpp_htlcs = Vec::new();
-                       let mut pending_peers_awaiting_removal = HashSet::new();
+                       let mut pending_peers_awaiting_removal = Vec::new();
                        {
                                let per_peer_state = self.per_peer_state.read().unwrap();
                                for (counterparty_node_id, peer_state_mutex) in per_peer_state.iter() {
@@ -3574,13 +3536,38 @@ where
 
                                                true
                                        });
-                                       let peer_should_be_removed = !peer_state.is_connected && peer_state.channel_by_id.len() == 0;
-                                       if peer_should_be_removed {
-                                               pending_peers_awaiting_removal.insert(counterparty_node_id);
+                                       if peer_state.ok_to_remove(true) {
+                                               pending_peers_awaiting_removal.push(counterparty_node_id);
+                                       }
+                               }
+                       }
+
+                       // When a peer disconnects but still has channels, the peer's `peer_state` entry in the
+                       // `per_peer_state` is not removed by the `peer_disconnected` function. If the channels
+                       // of to that peer is later closed while still being disconnected (i.e. force closed),
+                       // we therefore need to remove the peer from `peer_state` separately.
+                       // To avoid having to take the `per_peer_state` `write` lock once the channels are
+                       // closed, we instead remove such peers awaiting removal here on a timer, to limit the
+                       // negative effects on parallelism as much as possible.
+                       if pending_peers_awaiting_removal.len() > 0 {
+                               let mut per_peer_state = self.per_peer_state.write().unwrap();
+                               for counterparty_node_id in pending_peers_awaiting_removal {
+                                       match per_peer_state.entry(counterparty_node_id) {
+                                               hash_map::Entry::Occupied(entry) => {
+                                                       // Remove the entry if the peer is still disconnected and we still
+                                                       // have no channels to the peer.
+                                                       let remove_entry = {
+                                                               let peer_state = entry.get().lock().unwrap();
+                                                               peer_state.ok_to_remove(true)
+                                                       };
+                                                       if remove_entry {
+                                                               entry.remove_entry();
+                                                       }
+                                               },
+                                               hash_map::Entry::Vacant(_) => { /* The PeerState has already been removed */ }
                                        }
                                }
                        }
-                       self.remove_peers_awaiting_removal(pending_peers_awaiting_removal);
 
                        self.claimable_payments.lock().unwrap().claimable_htlcs.retain(|payment_hash, (_, htlcs)| {
                                if htlcs.is_empty() {
@@ -3754,17 +3741,12 @@ where
        /// Fails an HTLC backwards to the sender of it to us.
        /// Note that we do not assume that channels corresponding to failed HTLCs are still available.
        fn fail_htlc_backwards_internal(&self, source: &HTLCSource, payment_hash: &PaymentHash, onion_error: &HTLCFailReason, destination: HTLCDestination) {
-               #[cfg(any(feature = "_test_utils", test))]
-               {
-                       // Ensure that the peer state channel storage lock is not held when calling this
-                       // function.
-                       // This ensures that future code doesn't introduce a lock_order requirement for
-                       // `forward_htlcs` to be locked after the `per_peer_state` peer locks, which calling
-                       // this function with any `per_peer_state` peer lock aquired would.
-                       let per_peer_state = self.per_peer_state.read().unwrap();
-                       for (_, peer) in per_peer_state.iter() {
-                               debug_assert!(peer.try_lock().is_ok());
-                       }
+               // Ensure that no peer state channel storage lock is held when calling this function.
+               // This ensures that future code doesn't introduce a lock-order requirement for
+               // `forward_htlcs` to be locked after the `per_peer_state` peer locks, which calling
+               // this function with any `per_peer_state` peer lock acquired would.
+               for (_, peer) in self.per_peer_state.read().unwrap().iter() {
+                       debug_assert_ne!(peer.held_by_thread(), LockHeldState::HeldByThread);
                }
 
                //TODO: There is a timing attack here where if a node fails an HTLC back to us they can
@@ -4317,7 +4299,7 @@ where
 
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(counterparty_node_id)
-                       .ok_or_else(|| APIError::APIMisuseError{ err: format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id) })?;
+                       .ok_or_else(|| APIError::ChannelUnavailable { err: format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id) })?;
                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                match peer_state.channel_by_id.entry(temporary_channel_id.clone()) {
@@ -4367,7 +4349,10 @@ where
                let outbound_scid_alias = self.create_and_insert_outbound_scid_alias();
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(counterparty_node_id)
-                   .ok_or_else(|| MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.temporary_channel_id.clone()))?;
+                   .ok_or_else(|| {
+                               debug_assert!(false);
+                               MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.temporary_channel_id.clone())
+                       })?;
                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                let mut channel = match Channel::new_from_req(&self.fee_estimator, &self.entropy_source, &self.signer_provider,
@@ -4417,7 +4402,10 @@ where
                let (value, output_script, user_id) = {
                        let per_peer_state = self.per_peer_state.read().unwrap();
                        let peer_state_mutex = per_peer_state.get(counterparty_node_id)
-                               .ok_or_else(|| MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.temporary_channel_id))?;
+                               .ok_or_else(|| {
+                                       debug_assert!(false);
+                                       MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.temporary_channel_id)
+                               })?;
                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        match peer_state.channel_by_id.entry(msg.temporary_channel_id) {
@@ -4442,7 +4430,10 @@ where
        fn internal_funding_created(&self, counterparty_node_id: &PublicKey, msg: &msgs::FundingCreated) -> Result<(), MsgHandleErrInternal> {
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(counterparty_node_id)
-                       .ok_or_else(|| MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.temporary_channel_id))?;
+                       .ok_or_else(|| {
+                               debug_assert!(false);
+                               MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.temporary_channel_id)
+                       })?;
                let ((funding_msg, monitor, mut channel_ready), mut chan) = {
                        let best_block = *self.best_block.read().unwrap();
                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
@@ -4518,7 +4509,10 @@ where
                        let best_block = *self.best_block.read().unwrap();
                        let per_peer_state = self.per_peer_state.read().unwrap();
                        let peer_state_mutex = per_peer_state.get(counterparty_node_id)
-                               .ok_or_else(|| MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id))?;
+                               .ok_or_else(|| {
+                                       debug_assert!(false);
+                                       MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
+                               })?;
 
                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
@@ -4559,7 +4553,10 @@ where
        fn internal_channel_ready(&self, counterparty_node_id: &PublicKey, msg: &msgs::ChannelReady) -> Result<(), MsgHandleErrInternal> {
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(counterparty_node_id)
-                       .ok_or_else(|| MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id))?;
+                       .ok_or_else(|| {
+                               debug_assert!(false);
+                               MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
+                       })?;
                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                match peer_state.channel_by_id.entry(msg.channel_id) {
@@ -4600,7 +4597,10 @@ where
                let result: Result<(), _> = loop {
                        let per_peer_state = self.per_peer_state.read().unwrap();
                        let peer_state_mutex = per_peer_state.get(counterparty_node_id)
-                               .ok_or_else(|| MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id))?;
+                               .ok_or_else(|| {
+                                       debug_assert!(false);
+                                       MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
+                               })?;
                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        match peer_state.channel_by_id.entry(msg.channel_id.clone()) {
@@ -4651,7 +4651,10 @@ where
        fn internal_closing_signed(&self, counterparty_node_id: &PublicKey, msg: &msgs::ClosingSigned) -> Result<(), MsgHandleErrInternal> {
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(counterparty_node_id)
-                       .ok_or_else(|| MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id))?;
+                       .ok_or_else(|| {
+                               debug_assert!(false);
+                               MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
+                       })?;
                let (tx, chan_option) = {
                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
@@ -4706,7 +4709,10 @@ where
                let pending_forward_info = self.decode_update_add_htlc_onion(msg);
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(counterparty_node_id)
-                       .ok_or_else(|| MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id))?;
+                       .ok_or_else(|| {
+                               debug_assert!(false);
+                               MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
+                       })?;
                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                match peer_state.channel_by_id.entry(msg.channel_id) {
@@ -4745,7 +4751,10 @@ where
                let (htlc_source, forwarded_htlc_value) = {
                        let per_peer_state = self.per_peer_state.read().unwrap();
                        let peer_state_mutex = per_peer_state.get(counterparty_node_id)
-                               .ok_or_else(|| MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id))?;
+                               .ok_or_else(|| {
+                                       debug_assert!(false);
+                                       MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
+                               })?;
                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        match peer_state.channel_by_id.entry(msg.channel_id) {
@@ -4762,7 +4771,10 @@ where
        fn internal_update_fail_htlc(&self, counterparty_node_id: &PublicKey, msg: &msgs::UpdateFailHTLC) -> Result<(), MsgHandleErrInternal> {
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(counterparty_node_id)
-                       .ok_or_else(|| MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id))?;
+                       .ok_or_else(|| {
+                               debug_assert!(false);
+                               MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
+                       })?;
                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                match peer_state.channel_by_id.entry(msg.channel_id) {
@@ -4777,7 +4789,10 @@ where
        fn internal_update_fail_malformed_htlc(&self, counterparty_node_id: &PublicKey, msg: &msgs::UpdateFailMalformedHTLC) -> Result<(), MsgHandleErrInternal> {
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(counterparty_node_id)
-                       .ok_or_else(|| MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id))?;
+                       .ok_or_else(|| {
+                               debug_assert!(false);
+                               MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
+                       })?;
                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                match peer_state.channel_by_id.entry(msg.channel_id) {
@@ -4796,7 +4811,10 @@ where
        fn internal_commitment_signed(&self, counterparty_node_id: &PublicKey, msg: &msgs::CommitmentSigned) -> Result<(), MsgHandleErrInternal> {
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(counterparty_node_id)
-                       .ok_or_else(|| MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id))?;
+                       .ok_or_else(|| {
+                               debug_assert!(false);
+                               MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
+                       })?;
                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                match peer_state.channel_by_id.entry(msg.channel_id) {
@@ -4937,7 +4955,10 @@ where
                let res = loop {
                        let per_peer_state = self.per_peer_state.read().unwrap();
                        let peer_state_mutex = per_peer_state.get(counterparty_node_id)
-                               .ok_or_else(|| MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id))?;
+                               .ok_or_else(|| {
+                                       debug_assert!(false);
+                                       MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
+                               })?;
                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        match peer_state.channel_by_id.entry(msg.channel_id) {
@@ -5000,7 +5021,10 @@ where
        fn internal_update_fee(&self, counterparty_node_id: &PublicKey, msg: &msgs::UpdateFee) -> Result<(), MsgHandleErrInternal> {
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(counterparty_node_id)
-                       .ok_or_else(|| MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id))?;
+                       .ok_or_else(|| {
+                               debug_assert!(false);
+                               MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
+                       })?;
                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                match peer_state.channel_by_id.entry(msg.channel_id) {
@@ -5015,7 +5039,10 @@ where
        fn internal_announcement_signatures(&self, counterparty_node_id: &PublicKey, msg: &msgs::AnnouncementSignatures) -> Result<(), MsgHandleErrInternal> {
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(counterparty_node_id)
-                       .ok_or_else(|| MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id))?;
+                       .ok_or_else(|| {
+                               debug_assert!(false);
+                               MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
+                       })?;
                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                match peer_state.channel_by_id.entry(msg.channel_id) {
@@ -5031,7 +5058,7 @@ where
                                        ), chan),
                                        // Note that announcement_signatures fails if the channel cannot be announced,
                                        // so get_channel_update_for_broadcast will never fail by the time we get here.
-                                       update_msg: self.get_channel_update_for_broadcast(chan.get()).unwrap(),
+                                       update_msg: Some(self.get_channel_update_for_broadcast(chan.get()).unwrap()),
                                });
                        },
                        hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Got a message for a channel from the wrong node! No such channel for the passed counterparty_node_id {}", counterparty_node_id), msg.channel_id))
@@ -5086,7 +5113,10 @@ where
                        let per_peer_state = self.per_peer_state.read().unwrap();
 
                        let peer_state_mutex = per_peer_state.get(counterparty_node_id)
-                               .ok_or_else(|| MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id))?;
+                               .ok_or_else(|| {
+                                       debug_assert!(false);
+                                       MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
+                               })?;
                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        match peer_state.channel_by_id.entry(msg.channel_id) {
@@ -5403,7 +5433,8 @@ where
        /// [`PaymentHash`] and [`PaymentPreimage`] for you.
        ///
        /// The [`PaymentPreimage`] will ultimately be returned to you in the [`PaymentClaimable`], which
-       /// will have the [`PaymentClaimable::payment_preimage`] field filled in. That should then be
+       /// will have the [`PaymentClaimable::purpose`] be [`PaymentPurpose::InvoicePayment`] with
+       /// its [`PaymentPurpose::InvoicePayment::payment_preimage`] field filled in. That should then be
        /// passed directly to [`claim_funds`].
        ///
        /// See [`create_inbound_payment_for_hash`] for detailed documentation on behavior and requirements.
@@ -5423,7 +5454,9 @@ where
        ///
        /// [`claim_funds`]: Self::claim_funds
        /// [`PaymentClaimable`]: events::Event::PaymentClaimable
-       /// [`PaymentClaimable::payment_preimage`]: events::Event::PaymentClaimable::payment_preimage
+       /// [`PaymentClaimable::purpose`]: events::Event::PaymentClaimable::purpose
+       /// [`PaymentPurpose::InvoicePayment`]: events::PaymentPurpose::InvoicePayment
+       /// [`PaymentPurpose::InvoicePayment::payment_preimage`]: events::PaymentPurpose::InvoicePayment::payment_preimage
        /// [`create_inbound_payment_for_hash`]: Self::create_inbound_payment_for_hash
        pub fn create_inbound_payment(&self, min_value_msat: Option<u64>, invoice_expiry_delta_secs: u32,
                min_final_cltv_expiry_delta: Option<u16>) -> Result<(PaymentHash, PaymentSecret), ()> {
@@ -5953,7 +5986,7 @@ where
                                                                                msg: announcement,
                                                                                // Note that announcement_signatures fails if the channel cannot be announced,
                                                                                // so get_channel_update_for_broadcast will never fail by the time we get here.
-                                                                               update_msg: self.get_channel_update_for_broadcast(channel).unwrap(),
+                                                                               update_msg: Some(self.get_channel_update_for_broadcast(channel).unwrap()),
                                                                        });
                                                                }
                                                        }
@@ -6233,9 +6266,8 @@ where
        fn peer_disconnected(&self, counterparty_node_id: &PublicKey, no_connection_possible: bool) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);
                let mut failed_channels = Vec::new();
-               let mut no_channels_remain = true;
                let mut per_peer_state = self.per_peer_state.write().unwrap();
-               {
+               let remove_peer = {
                        log_debug!(self.logger, "Marking channels with {} disconnected and generating channel_updates. We believe we {} make future connections to this peer.",
                                log_pubkey!(counterparty_node_id), if no_connection_possible { "cannot" } else { "can" });
                        if let Some(peer_state_mutex) = per_peer_state.get(counterparty_node_id) {
@@ -6248,8 +6280,6 @@ where
                                                update_maps_on_chan_removal!(self, chan);
                                                self.issue_channel_close_events(chan, ClosureReason::DisconnectedPeer);
                                                return false;
-                                       } else {
-                                               no_channels_remain = false;
                                        }
                                        true
                                });
@@ -6269,6 +6299,7 @@ where
                                                &events::MessageSendEvent::SendChannelAnnouncement { .. } => false,
                                                &events::MessageSendEvent::BroadcastChannelAnnouncement { .. } => true,
                                                &events::MessageSendEvent::BroadcastChannelUpdate { .. } => true,
+                                               &events::MessageSendEvent::BroadcastNodeAnnouncement { .. } => true,
                                                &events::MessageSendEvent::SendChannelUpdate { .. } => false,
                                                &events::MessageSendEvent::HandleError { .. } => false,
                                                &events::MessageSendEvent::SendChannelRangeQuery { .. } => false,
@@ -6279,9 +6310,10 @@ where
                                });
                                debug_assert!(peer_state.is_connected, "A disconnected peer cannot disconnect");
                                peer_state.is_connected = false;
-                       }
-               }
-               if no_channels_remain {
+                               peer_state.ok_to_remove(true)
+                       } else { true }
+               };
+               if remove_peer {
                        per_peer_state.remove(counterparty_node_id);
                }
                mem::drop(per_peer_state);
@@ -6309,6 +6341,7 @@ where
                                                channel_by_id: HashMap::new(),
                                                latest_features: init_msg.features.clone(),
                                                pending_msg_events: Vec::new(),
+                                               monitor_update_blocked_actions: BTreeMap::new(),
                                                is_connected: true,
                                        }));
                                },
@@ -6875,6 +6908,7 @@ where
                        best_block.block_hash().write(writer)?;
                }
 
+               let mut serializable_peer_count: u64 = 0;
                {
                        let per_peer_state = self.per_peer_state.read().unwrap();
                        let mut unfunded_channels = 0;
@@ -6882,6 +6916,9 @@ where
                        for (_, peer_state_mutex) in per_peer_state.iter() {
                                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                                let peer_state = &mut *peer_state_lock;
+                               if !peer_state.ok_to_remove(false) {
+                                       serializable_peer_count += 1;
+                               }
                                number_of_channels += peer_state.channel_by_id.len();
                                for (_, channel) in peer_state.channel_by_id.iter() {
                                        if !channel.is_funding_initiated() {
@@ -6932,11 +6969,27 @@ where
                        htlc_purposes.push(purpose);
                }
 
-               (per_peer_state.len() as u64).write(writer)?;
-               for (peer_pubkey, peer_state_mutex) in per_peer_state.iter() {
-                       peer_pubkey.write(writer)?;
-                       let peer_state = peer_state_mutex.lock().unwrap();
-                       peer_state.latest_features.write(writer)?;
+               let mut monitor_update_blocked_actions_per_peer = None;
+               let mut peer_states = Vec::new();
+               for (_, peer_state_mutex) in per_peer_state.iter() {
+                       peer_states.push(peer_state_mutex.lock().unwrap());
+               }
+
+               (serializable_peer_count).write(writer)?;
+               for ((peer_pubkey, _), peer_state) in per_peer_state.iter().zip(peer_states.iter()) {
+                       // Peers which we have no channels to should be dropped once disconnected. As we
+                       // disconnect all peers when shutting down and serializing the ChannelManager, we
+                       // consider all peers as disconnected here. There's therefore no need write peers with
+                       // no channels.
+                       if !peer_state.ok_to_remove(false) {
+                               peer_pubkey.write(writer)?;
+                               peer_state.latest_features.write(writer)?;
+                               if !peer_state.monitor_update_blocked_actions.is_empty() {
+                                       monitor_update_blocked_actions_per_peer
+                                               .get_or_insert_with(Vec::new)
+                                               .push((*peer_pubkey, &peer_state.monitor_update_blocked_actions));
+                               }
+                       }
                }
 
                let events = self.pending_events.lock().unwrap();
@@ -7023,6 +7076,7 @@ where
                        (3, pending_outbound_payments, required),
                        (4, pending_claiming_payments, option),
                        (5, self.our_network_pubkey, required),
+                       (6, monitor_update_blocked_actions_per_peer, option),
                        (7, self.fake_scid_rand_bytes, required),
                        (9, htlc_purposes, vec_type),
                        (11, self.probing_cookie_secret, required),
@@ -7335,6 +7389,7 @@ where
                                channel_by_id: peer_channels.remove(&peer_pubkey).unwrap_or(HashMap::new()),
                                latest_features: Readable::read(reader)?,
                                pending_msg_events: Vec::new(),
+                               monitor_update_blocked_actions: BTreeMap::new(),
                                is_connected: false,
                        };
                        per_peer_state.insert(peer_pubkey, Mutex::new(peer_state));
@@ -7391,12 +7446,14 @@ where
                let mut probing_cookie_secret: Option<[u8; 32]> = None;
                let mut claimable_htlc_purposes = None;
                let mut pending_claiming_payments = Some(HashMap::new());
+               let mut monitor_update_blocked_actions_per_peer = Some(Vec::new());
                read_tlv_fields!(reader, {
                        (1, pending_outbound_payments_no_retry, option),
                        (2, pending_intercepted_htlcs, option),
                        (3, pending_outbound_payments, option),
                        (4, pending_claiming_payments, option),
                        (5, received_network_pubkey, option),
+                       (6, monitor_update_blocked_actions_per_peer, option),
                        (7, fake_scid_rand_bytes, option),
                        (9, claimable_htlc_purposes, vec_type),
                        (11, probing_cookie_secret, option),
@@ -7662,6 +7719,15 @@ where
                        }
                }
 
+               for (node_id, monitor_update_blocked_actions) in monitor_update_blocked_actions_per_peer.unwrap() {
+                       if let Some(peer_state) = per_peer_state.get_mut(&node_id) {
+                               peer_state.lock().unwrap().monitor_update_blocked_actions = monitor_update_blocked_actions;
+                       } else {
+                               log_error!(args.logger, "Got blocked actions without a per-peer-state for {}", node_id);
+                               return Err(DecodeError::InvalidValue);
+                       }
+               }
+
                let channel_manager = ChannelManager {
                        genesis_hash,
                        fee_estimator: bounded_fee_estimator,
@@ -7673,7 +7739,7 @@ where
 
                        inbound_payment_key: expanded_inbound_key,
                        pending_inbound_payments: Mutex::new(pending_inbound_payments),
-                       pending_outbound_payments: OutboundPayments { pending_outbound_payments: Mutex::new(pending_outbound_payments.unwrap()) },
+                       pending_outbound_payments: OutboundPayments { pending_outbound_payments: Mutex::new(pending_outbound_payments.unwrap()), retry_lock: Mutex::new(()), },
                        pending_intercepted_htlcs: Mutex::new(pending_intercepted_htlcs.unwrap()),
 
                        forward_htlcs: Mutex::new(forward_htlcs),
@@ -7723,19 +7789,14 @@ where
 mod tests {
        use bitcoin::hashes::Hash;
        use bitcoin::hashes::sha256::Hash as Sha256;
-       use bitcoin::hashes::hex::FromHex;
        use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
-       use bitcoin::secp256k1::ecdsa::Signature;
-       use bitcoin::secp256k1::ffi::Signature as FFISignature;
-       use bitcoin::blockdata::script::Script;
-       use bitcoin::Txid;
        use core::time::Duration;
        use core::sync::atomic::Ordering;
        use crate::ln::{PaymentPreimage, PaymentHash, PaymentSecret};
        use crate::ln::channelmanager::{inbound_payment, PaymentId, PaymentSendFailure, InterceptId};
        use crate::ln::functional_test_utils::*;
        use crate::ln::msgs;
-       use crate::ln::msgs::{ChannelMessageHandler, OptionalField};
+       use crate::ln::msgs::ChannelMessageHandler;
        use crate::routing::router::{PaymentParameters, RouteParameters, find_route};
        use crate::util::errors::APIError;
        use crate::util::events::{Event, HTLCDestination, MessageSendEvent, MessageSendEventsProvider, ClosureReason};
@@ -7952,7 +8013,7 @@ mod tests {
                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);
-               let scorer = test_utils::TestScorer::with_penalty(0);
+               let scorer = test_utils::TestScorer::new();
                let random_seed_bytes = chanmon_cfgs[1].keys_manager.get_secure_random_bytes();
 
                // To start (1), send a regular payment but don't claim it.
@@ -8058,7 +8119,7 @@ mod tests {
                };
                let network_graph = nodes[0].network_graph.clone();
                let first_hops = nodes[0].node.list_usable_channels();
-               let scorer = test_utils::TestScorer::with_penalty(0);
+               let scorer = test_utils::TestScorer::new();
                let random_seed_bytes = chanmon_cfgs[1].keys_manager.get_secure_random_bytes();
                let route = find_route(
                        &payer_pubkey, &route_params, &network_graph, Some(&first_hops.iter().collect::<Vec<_>>()),
@@ -8101,7 +8162,7 @@ mod tests {
                };
                let network_graph = nodes[0].network_graph.clone();
                let first_hops = nodes[0].node.list_usable_channels();
-               let scorer = test_utils::TestScorer::with_penalty(0);
+               let scorer = test_utils::TestScorer::new();
                let random_seed_bytes = chanmon_cfgs[1].keys_manager.get_secure_random_bytes();
                let route = find_route(
                        &payer_pubkey, &route_params, &network_graph, Some(&first_hops.iter().collect::<Vec<_>>()),
@@ -8334,19 +8395,22 @@ mod tests {
 
        fn check_not_connected_to_peer_error<T>(res_err: Result<T, APIError>, expected_public_key: PublicKey) {
                let expected_message = format!("Not connected to node: {}", expected_public_key);
-               check_api_misuse_error_message(expected_message, res_err)
+               check_api_error_message(expected_message, res_err)
        }
 
        fn check_unkown_peer_error<T>(res_err: Result<T, APIError>, expected_public_key: PublicKey) {
                let expected_message = format!("Can't find a peer matching the passed counterparty node_id {}", expected_public_key);
-               check_api_misuse_error_message(expected_message, res_err)
+               check_api_error_message(expected_message, res_err)
        }
 
-       fn check_api_misuse_error_message<T>(expected_err_message: String, res_err: Result<T, APIError>) {
+       fn check_api_error_message<T>(expected_err_message: String, res_err: Result<T, APIError>) {
                match res_err {
                        Err(APIError::APIMisuseError { err }) => {
                                assert_eq!(err, expected_err_message);
                        },
+                       Err(APIError::ChannelUnavailable { err }) => {
+                               assert_eq!(err, expected_err_message);
+                       },
                        Ok(_) => panic!("Unexpected Ok"),
                        Err(_) => panic!("Unexpected Error"),
                }
@@ -8354,140 +8418,23 @@ mod tests {
 
        #[test]
        fn test_api_calls_with_unkown_counterparty_node() {
-               // Tests that our API functions and message handlers that expects a `counterparty_node_id`
-               // as input, behaves as expected if the `counterparty_node_id` is an unkown peer in the
+               // Tests that our API functions that expects a `counterparty_node_id` as input, behaves as
+               // expected if the `counterparty_node_id` is an unkown peer in the
                // `ChannelManager::per_peer_state` map.
                let chanmon_cfg = create_chanmon_cfgs(2);
                let node_cfg = create_node_cfgs(2, &chanmon_cfg);
                let node_chanmgr = create_node_chanmgrs(2, &node_cfg, &[None, None]);
                let nodes = create_network(2, &node_cfg, &node_chanmgr);
 
-               // Boilerplate code to produce `open_channel` and `accept_channel` msgs more densly than
-               // creating dummy ones.
-               nodes[0].node.create_channel(nodes[1].node.get_our_node_id(), 1_000_000, 500_000_000, 42, None).unwrap();
-               let open_channel_msg = get_event_msg!(nodes[0], MessageSendEvent::SendOpenChannel, nodes[1].node.get_our_node_id());
-               nodes[1].node.handle_open_channel(&nodes[0].node.get_our_node_id(), &open_channel_msg);
-               let accept_channel_msg = get_event_msg!(nodes[1], MessageSendEvent::SendAcceptChannel, nodes[0].node.get_our_node_id());
-
                // Dummy values
                let channel_id = [4; 32];
-               let signature = Signature::from(unsafe { FFISignature::new() });
                let unkown_public_key = PublicKey::from_secret_key(&Secp256k1::signing_only(), &SecretKey::from_slice(&[42; 32]).unwrap());
                let intercept_id = InterceptId([0; 32]);
 
-               // Dummy msgs
-               let funding_created_msg = msgs::FundingCreated {
-                       temporary_channel_id: open_channel_msg.temporary_channel_id,
-                       funding_txid: Txid::from_hex("ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff").unwrap(),
-                       funding_output_index: 0,
-                       signature: signature,
-               };
-
-               let funding_signed_msg = msgs::FundingSigned {
-                       channel_id: channel_id,
-                       signature: signature,
-               };
-
-               let channel_ready_msg = msgs::ChannelReady {
-                       channel_id: channel_id,
-                       next_per_commitment_point: unkown_public_key,
-                       short_channel_id_alias: None,
-               };
-
-               let announcement_signatures_msg = msgs::AnnouncementSignatures {
-                       channel_id: channel_id,
-                       short_channel_id: 0,
-                       node_signature: signature,
-                       bitcoin_signature: signature,
-               };
-
-               let channel_reestablish_msg = msgs::ChannelReestablish {
-                       channel_id: channel_id,
-                       next_local_commitment_number: 0,
-                       next_remote_commitment_number: 0,
-                       data_loss_protect: OptionalField::Absent,
-               };
-
-               let closing_signed_msg = msgs::ClosingSigned {
-                       channel_id: channel_id,
-                       fee_satoshis: 1000,
-                       signature: signature,
-                       fee_range: None,
-               };
-
-               let shutdown_msg = msgs::Shutdown {
-                       channel_id: channel_id,
-                       scriptpubkey: Script::new(),
-               };
-
-               let onion_routing_packet = msgs::OnionPacket {
-                       version: 255,
-                       public_key: Ok(unkown_public_key),
-                       hop_data: [1; 20*65],
-                       hmac: [2; 32]
-               };
-
-               let update_add_htlc_msg = msgs::UpdateAddHTLC {
-                       channel_id: channel_id,
-                       htlc_id: 0,
-                       amount_msat: 1000000,
-                       payment_hash: PaymentHash([1; 32]),
-                       cltv_expiry: 821716,
-                       onion_routing_packet
-               };
-
-               let commitment_signed_msg = msgs::CommitmentSigned {
-                       channel_id: channel_id,
-                       signature: signature,
-                       htlc_signatures: Vec::new(),
-               };
-
-               let update_fee_msg = msgs::UpdateFee {
-                       channel_id: channel_id,
-                       feerate_per_kw: 1000,
-               };
-
-               let malformed_update_msg = msgs::UpdateFailMalformedHTLC{
-                       channel_id: channel_id,
-                       htlc_id: 0,
-                       sha256_of_onion: [1; 32],
-                       failure_code: 0x8000,
-               };
-
-               let fulfill_update_msg = msgs::UpdateFulfillHTLC{
-                       channel_id: channel_id,
-                       htlc_id: 0,
-                       payment_preimage: PaymentPreimage([1; 32]),
-               };
-
-               let fail_update_msg = msgs::UpdateFailHTLC{
-                       channel_id: channel_id,
-                       htlc_id: 0,
-                       reason: msgs::OnionErrorPacket { data: Vec::new()},
-               };
-
-               let revoke_and_ack_msg = msgs::RevokeAndACK {
-                       channel_id: channel_id,
-                       per_commitment_secret: [1; 32],
-                       next_per_commitment_point: unkown_public_key,
-               };
-
-               // Test the API functions and message handlers.
+               // Test the API functions.
                check_not_connected_to_peer_error(nodes[0].node.create_channel(unkown_public_key, 1_000_000, 500_000_000, 42, None), unkown_public_key);
 
-               nodes[1].node.handle_open_channel(&unkown_public_key, &open_channel_msg);
-
-               nodes[0].node.handle_accept_channel(&unkown_public_key, &accept_channel_msg);
-
-               check_unkown_peer_error(nodes[0].node.accept_inbound_channel(&open_channel_msg.temporary_channel_id, &unkown_public_key, 42), unkown_public_key);
-
-               nodes[1].node.handle_funding_created(&unkown_public_key, &funding_created_msg);
-
-               nodes[0].node.handle_funding_signed(&unkown_public_key, &funding_signed_msg);
-
-               nodes[0].node.handle_channel_ready(&unkown_public_key, &channel_ready_msg);
-
-               nodes[1].node.handle_announcement_signatures(&unkown_public_key, &announcement_signatures_msg);
+               check_unkown_peer_error(nodes[0].node.accept_inbound_channel(&channel_id, &unkown_public_key, 42), unkown_public_key);
 
                check_unkown_peer_error(nodes[0].node.close_channel(&channel_id, &unkown_public_key), unkown_public_key);
 
@@ -8498,26 +8445,6 @@ mod tests {
                check_unkown_peer_error(nodes[0].node.forward_intercepted_htlc(intercept_id, &channel_id, unkown_public_key, 1_000_000), unkown_public_key);
 
                check_unkown_peer_error(nodes[0].node.update_channel_config(&unkown_public_key, &[channel_id], &ChannelConfig::default()), unkown_public_key);
-
-               nodes[0].node.handle_shutdown(&unkown_public_key, &shutdown_msg);
-
-               nodes[1].node.handle_closing_signed(&unkown_public_key, &closing_signed_msg);
-
-               nodes[0].node.handle_channel_reestablish(&unkown_public_key, &channel_reestablish_msg);
-
-               nodes[1].node.handle_update_add_htlc(&unkown_public_key, &update_add_htlc_msg);
-
-               nodes[1].node.handle_commitment_signed(&unkown_public_key, &commitment_signed_msg);
-
-               nodes[1].node.handle_update_fail_malformed_htlc(&unkown_public_key, &malformed_update_msg);
-
-               nodes[1].node.handle_update_fail_htlc(&unkown_public_key, &fail_update_msg);
-
-               nodes[1].node.handle_update_fulfill_htlc(&unkown_public_key, &fulfill_update_msg);
-
-               nodes[1].node.handle_revoke_and_ack(&unkown_public_key, &revoke_and_ack_msg);
-
-               nodes[1].node.handle_update_fee(&unkown_public_key, &update_fee_msg);
        }
 
        #[cfg(anchors)]
@@ -8605,7 +8532,8 @@ pub mod bench {
                let tx_broadcaster = test_utils::TestBroadcaster{txn_broadcasted: Mutex::new(Vec::new()), blocks: Arc::new(Mutex::new(Vec::new()))};
                let fee_estimator = test_utils::TestFeeEstimator { sat_per_kw: Mutex::new(253) };
                let logger_a = test_utils::TestLogger::with_id("node a".to_owned());
-               let router = test_utils::TestRouter::new(Arc::new(NetworkGraph::new(genesis_hash, &logger_a)));
+               let scorer = Mutex::new(test_utils::TestScorer::new());
+               let router = test_utils::TestRouter::new(Arc::new(NetworkGraph::new(genesis_hash, &logger_a)), &scorer);
 
                let mut config: UserConfig = Default::default();
                config.channel_handshake_config.minimum_depth = 1;
@@ -8696,7 +8624,7 @@ pub mod bench {
                                let usable_channels = $node_a.list_usable_channels();
                                let payment_params = PaymentParameters::from_node_id($node_b.get_our_node_id(), TEST_FINAL_CLTV)
                                        .with_features($node_b.invoice_features());
-                               let scorer = test_utils::TestScorer::with_penalty(0);
+                               let scorer = test_utils::TestScorer::new();
                                let seed = [3u8; 32];
                                let keys_manager = KeysManager::new(&seed, 42, 42);
                                let random_seed_bytes = keys_manager.get_secure_random_bytes();