Merge pull request #2368 from wpaulino/inbound-anchors-manual-acceptance
[rust-lightning] / lightning / src / ln / channelmanager.rs
index fd536a1360c9a1498d39e035390a5a1b66ce2e81..a03f11d57443f340713909cac761e057d7637ead 100644 (file)
@@ -40,7 +40,7 @@ use crate::events::{Event, EventHandler, EventsProvider, MessageSendEvent, Messa
 // Since this struct is returned in `list_channels` methods, expose it here in case users want to
 // construct one themselves.
 use crate::ln::{inbound_payment, PaymentHash, PaymentPreimage, PaymentSecret};
-use crate::ln::channel::{Channel, ChannelError, ChannelUpdateStatus, ShutdownResult, UpdateFulfillCommitFetch};
+use crate::ln::channel::{Channel, ChannelContext, ChannelError, ChannelUpdateStatus, ShutdownResult, UpdateFulfillCommitFetch, OutboundV1Channel, InboundV1Channel};
 use crate::ln::features::{ChannelFeatures, ChannelTypeFeatures, InitFeatures, NodeFeatures};
 #[cfg(any(feature = "_test_utils", test))]
 use crate::ln::features::InvoiceFeatures;
@@ -50,7 +50,7 @@ use crate::routing::scoring::{ProbabilisticScorer, ProbabilisticScoringFeeParame
 use crate::ln::msgs;
 use crate::ln::onion_utils;
 use crate::ln::onion_utils::HTLCFailReason;
-use crate::ln::msgs::{ChannelMessageHandler, DecodeError, LightningError, MAX_VALUE_MSAT};
+use crate::ln::msgs::{ChannelMessageHandler, DecodeError, LightningError};
 #[cfg(test)]
 use crate::ln::outbound_payment;
 use crate::ln::outbound_payment::{OutboundPayments, PaymentAttempts, PendingOutboundPayment};
@@ -131,6 +131,9 @@ pub(super) struct PendingHTLCInfo {
        /// may overshoot this in either case)
        pub(super) outgoing_amt_msat: u64,
        pub(super) outgoing_cltv_value: u32,
+       /// The fee being skimmed off the top of this HTLC. If this is a forward, it'll be the fee we are
+       /// skimming. If we're receiving this HTLC, it's the fee that our counterparty skimmed.
+       pub(super) skimmed_fee_msat: Option<u64>,
 }
 
 #[derive(Clone)] // See Channel::revoke_and_ack for why, tl;dr: Rust bug
@@ -210,6 +213,8 @@ struct ClaimableHTLC {
        total_value_received: Option<u64>,
        /// The sender intended sum total of all MPP parts specified in the onion
        total_msat: u64,
+       /// The extra fee our counterparty skimmed off the top of this HTLC.
+       counterparty_skimmed_fee_msat: Option<u64>,
 }
 
 /// A payment identifier used to uniquely identify a payment to LDK.
@@ -607,17 +612,34 @@ impl_writeable_tlv_based_enum!(RAAMonitorUpdateBlockingAction,
 
 /// State we hold per-peer.
 pub(super) struct PeerState<Signer: ChannelSigner> {
-       /// `temporary_channel_id` or `channel_id` -> `channel`.
+       /// `channel_id` -> `Channel`.
        ///
-       /// Holds all channels where the peer is the counterparty. Once a channel has been assigned a
-       /// `channel_id`, the `temporary_channel_id` key in the map is updated and is replaced by the
-       /// `channel_id`.
+       /// Holds all funded channels where the peer is the counterparty.
        pub(super) channel_by_id: HashMap<[u8; 32], Channel<Signer>>,
+       /// `temporary_channel_id` -> `OutboundV1Channel`.
+       ///
+       /// Holds all outbound V1 channels where the peer is the counterparty. Once an outbound channel has
+       /// been assigned a `channel_id`, the entry in this map is removed and one is created in
+       /// `channel_by_id`.
+       pub(super) outbound_v1_channel_by_id: HashMap<[u8; 32], OutboundV1Channel<Signer>>,
+       /// `temporary_channel_id` -> `InboundV1Channel`.
+       ///
+       /// Holds all inbound V1 channels where the peer is the counterparty. Once an inbound channel has
+       /// been assigned a `channel_id`, the entry in this map is removed and one is created in
+       /// `channel_by_id`.
+       pub(super) inbound_v1_channel_by_id: HashMap<[u8; 32], InboundV1Channel<Signer>>,
        /// The latest `InitFeatures` we heard from the peer.
        latest_features: InitFeatures,
        /// 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 Channel IDs to pending [`ChannelMonitorUpdate`]s which have been passed to the
+       /// user but which have not yet completed.
+       ///
+       /// Note that the channel may no longer exist. For example if the 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.
+       in_flight_monitor_updates: BTreeMap<OutPoint, Vec<ChannelMonitorUpdate>>,
        /// Map from a specific channel to some action(s) that should be taken when all pending
        /// [`ChannelMonitorUpdate`]s for the channel complete updating.
        ///
@@ -653,6 +675,21 @@ impl <Signer: ChannelSigner> PeerState<Signer> {
                        return false
                }
                self.channel_by_id.is_empty() && self.monitor_update_blocked_actions.is_empty()
+                       && self.in_flight_monitor_updates.is_empty()
+       }
+
+       // Returns a count of all channels we have with this peer, including pending channels.
+       fn total_channel_count(&self) -> usize {
+               self.channel_by_id.len() +
+                       self.outbound_v1_channel_by_id.len() +
+                       self.inbound_v1_channel_by_id.len()
+       }
+
+       // Returns a bool indicating if the given `channel_id` matches a channel we have with this peer.
+       fn has_channel(&self, channel_id: &[u8; 32]) -> bool {
+               self.channel_by_id.contains_key(channel_id) ||
+                       self.outbound_v1_channel_by_id.contains_key(channel_id) ||
+                       self.inbound_v1_channel_by_id.contains_key(channel_id)
        }
 }
 
@@ -1466,54 +1503,54 @@ impl ChannelDetails {
                self.short_channel_id.or(self.outbound_scid_alias)
        }
 
-       fn from_channel<Signer: WriteableEcdsaChannelSigner>(channel: &Channel<Signer>,
+       fn from_channel_context<Signer: WriteableEcdsaChannelSigner>(context: &ChannelContext<Signer>,
                best_block_height: u32, latest_features: InitFeatures) -> Self {
 
-               let balance = channel.get_available_balances();
+               let balance = context.get_available_balances();
                let (to_remote_reserve_satoshis, to_self_reserve_satoshis) =
-                       channel.get_holder_counterparty_selected_channel_reserve_satoshis();
+                       context.get_holder_counterparty_selected_channel_reserve_satoshis();
                ChannelDetails {
-                       channel_id: channel.context.channel_id(),
+                       channel_id: context.channel_id(),
                        counterparty: ChannelCounterparty {
-                               node_id: channel.context.get_counterparty_node_id(),
+                               node_id: context.get_counterparty_node_id(),
                                features: latest_features,
                                unspendable_punishment_reserve: to_remote_reserve_satoshis,
-                               forwarding_info: channel.counterparty_forwarding_info(),
+                               forwarding_info: context.counterparty_forwarding_info(),
                                // Ensures that we have actually received the `htlc_minimum_msat` value
                                // from the counterparty through the `OpenChannel` or `AcceptChannel`
                                // message (as they are always the first message from the counterparty).
                                // Else `Channel::get_counterparty_htlc_minimum_msat` could return the
                                // default `0` value set by `Channel::new_outbound`.
-                               outbound_htlc_minimum_msat: if channel.context.have_received_message() {
-                                       Some(channel.context.get_counterparty_htlc_minimum_msat()) } else { None },
-                               outbound_htlc_maximum_msat: channel.context.get_counterparty_htlc_maximum_msat(),
+                               outbound_htlc_minimum_msat: if context.have_received_message() {
+                                       Some(context.get_counterparty_htlc_minimum_msat()) } else { None },
+                               outbound_htlc_maximum_msat: context.get_counterparty_htlc_maximum_msat(),
                        },
-                       funding_txo: channel.context.get_funding_txo(),
+                       funding_txo: context.get_funding_txo(),
                        // Note that accept_channel (or open_channel) is always the first message, so
                        // `have_received_message` indicates that type negotiation has completed.
-                       channel_type: if channel.context.have_received_message() { Some(channel.context.get_channel_type().clone()) } else { None },
-                       short_channel_id: channel.context.get_short_channel_id(),
-                       outbound_scid_alias: if channel.context.is_usable() { Some(channel.context.outbound_scid_alias()) } else { None },
-                       inbound_scid_alias: channel.context.latest_inbound_scid_alias(),
-                       channel_value_satoshis: channel.context.get_value_satoshis(),
-                       feerate_sat_per_1000_weight: Some(channel.get_feerate_sat_per_1000_weight()),
+                       channel_type: if context.have_received_message() { Some(context.get_channel_type().clone()) } else { None },
+                       short_channel_id: context.get_short_channel_id(),
+                       outbound_scid_alias: if context.is_usable() { Some(context.outbound_scid_alias()) } else { None },
+                       inbound_scid_alias: context.latest_inbound_scid_alias(),
+                       channel_value_satoshis: context.get_value_satoshis(),
+                       feerate_sat_per_1000_weight: Some(context.get_feerate_sat_per_1000_weight()),
                        unspendable_punishment_reserve: to_self_reserve_satoshis,
                        balance_msat: balance.balance_msat,
                        inbound_capacity_msat: balance.inbound_capacity_msat,
                        outbound_capacity_msat: balance.outbound_capacity_msat,
                        next_outbound_htlc_limit_msat: balance.next_outbound_htlc_limit_msat,
                        next_outbound_htlc_minimum_msat: balance.next_outbound_htlc_minimum_msat,
-                       user_channel_id: channel.context.get_user_id(),
-                       confirmations_required: channel.context.minimum_depth(),
-                       confirmations: Some(channel.context.get_funding_tx_confirmations(best_block_height)),
-                       force_close_spend_delay: channel.context.get_counterparty_selected_contest_delay(),
-                       is_outbound: channel.context.is_outbound(),
-                       is_channel_ready: channel.context.is_usable(),
-                       is_usable: channel.context.is_live(),
-                       is_public: channel.context.should_announce(),
-                       inbound_htlc_minimum_msat: Some(channel.context.get_holder_htlc_minimum_msat()),
-                       inbound_htlc_maximum_msat: channel.context.get_holder_htlc_maximum_msat(),
-                       config: Some(channel.context.config()),
+                       user_channel_id: context.get_user_id(),
+                       confirmations_required: context.minimum_depth(),
+                       confirmations: Some(context.get_funding_tx_confirmations(best_block_height)),
+                       force_close_spend_delay: context.get_counterparty_selected_contest_delay(),
+                       is_outbound: context.is_outbound(),
+                       is_channel_ready: context.is_usable(),
+                       is_usable: context.is_live(),
+                       is_public: context.should_announce(),
+                       inbound_htlc_minimum_msat: Some(context.get_holder_htlc_minimum_msat()),
+                       inbound_htlc_maximum_msat: context.get_holder_htlc_maximum_msat(),
+                       config: Some(context.config()),
                }
        }
 }
@@ -1610,14 +1647,23 @@ macro_rules! handle_error {
                                Err(err)
                        },
                }
-       } }
+       } };
+       ($self: ident, $internal: expr) => {
+               match $internal {
+                       Ok(res) => Ok(res),
+                       Err((chan, msg_handle_err)) => {
+                               let counterparty_node_id = chan.get_counterparty_node_id();
+                               handle_error!($self, Err(msg_handle_err), counterparty_node_id).map_err(|err| (chan, err))
+                       },
+               }
+       };
 }
 
 macro_rules! update_maps_on_chan_removal {
-       ($self: expr, $channel: expr) => {{
-               $self.id_to_peer.lock().unwrap().remove(&$channel.context.channel_id());
+       ($self: expr, $channel_context: expr) => {{
+               $self.id_to_peer.lock().unwrap().remove(&$channel_context.channel_id());
                let mut short_to_chan_info = $self.short_to_chan_info.write().unwrap();
-               if let Some(short_id) = $channel.context.get_short_channel_id() {
+               if let Some(short_id) = $channel_context.get_short_channel_id() {
                        short_to_chan_info.remove(&short_id);
                } else {
                        // If the channel was never confirmed on-chain prior to its closure, remove the
@@ -1626,10 +1672,10 @@ macro_rules! update_maps_on_chan_removal {
                        // also don't want a counterparty to be able to trivially cause a memory leak by simply
                        // opening a million channels with us which are closed before we ever reach the funding
                        // stage.
-                       let alias_removed = $self.outbound_scid_aliases.lock().unwrap().remove(&$channel.context.outbound_scid_alias());
+                       let alias_removed = $self.outbound_scid_aliases.lock().unwrap().remove(&$channel_context.outbound_scid_alias());
                        debug_assert!(alias_removed);
                }
-               short_to_chan_info.remove(&$channel.context.outbound_scid_alias());
+               short_to_chan_info.remove(&$channel_context.outbound_scid_alias());
        }}
 }
 
@@ -1645,12 +1691,25 @@ macro_rules! convert_chan_err {
                        },
                        ChannelError::Close(msg) => {
                                log_error!($self.logger, "Closing channel {} due to close-required error: {}", log_bytes!($channel_id[..]), msg);
-                               update_maps_on_chan_removal!($self, $channel);
-                               let shutdown_res = $channel.force_shutdown(true);
+                               update_maps_on_chan_removal!($self, &$channel.context);
+                               let shutdown_res = $channel.context.force_shutdown(true);
                                (true, MsgHandleErrInternal::from_finish_shutdown(msg, *$channel_id, $channel.context.get_user_id(),
                                        shutdown_res, $self.get_channel_update_for_broadcast(&$channel).ok()))
                        },
                }
+       };
+       ($self: ident, $err: expr, $channel_context: expr, $channel_id: expr, PREFUNDED) => {
+               match $err {
+                       // We should only ever have `ChannelError::Close` when prefunded channels error.
+                       // In any case, just close the channel.
+                       ChannelError::Warn(msg) | ChannelError::Ignore(msg) | ChannelError::Close(msg) => {
+                               log_error!($self.logger, "Closing prefunded channel {} due to an error: {}", log_bytes!($channel_id[..]), msg);
+                               update_maps_on_chan_removal!($self, &$channel_context);
+                               let shutdown_res = $channel_context.force_shutdown(false);
+                               (true, MsgHandleErrInternal::from_finish_shutdown(msg, *$channel_id, $channel_context.get_user_id(),
+                                       shutdown_res, None))
+                       },
+               }
        }
 }
 
@@ -1669,6 +1728,21 @@ macro_rules! break_chan_entry {
        }
 }
 
+macro_rules! try_v1_outbound_chan_entry {
+       ($self: ident, $res: expr, $entry: expr) => {
+               match $res {
+                       Ok(res) => res,
+                       Err(e) => {
+                               let (drop, res) = convert_chan_err!($self, e, $entry.get_mut().context, $entry.key(), PREFUNDED);
+                               if drop {
+                                       $entry.remove_entry();
+                               }
+                               return Err(res);
+                       }
+               }
+       }
+}
+
 macro_rules! try_chan_entry {
        ($self: ident, $res: expr, $entry: expr) => {
                match $res {
@@ -1688,7 +1762,7 @@ macro_rules! remove_channel {
        ($self: expr, $entry: expr) => {
                {
                        let channel = $entry.remove_entry().1;
-                       update_maps_on_chan_removal!($self, channel);
+                       update_maps_on_chan_removal!($self, &channel.context);
                        channel
                }
        }
@@ -1745,7 +1819,7 @@ macro_rules! emit_channel_ready_event {
 }
 
 macro_rules! handle_monitor_update_completion {
-       ($self: ident, $update_id: expr, $peer_state_lock: expr, $peer_state: expr, $per_peer_state_lock: expr, $chan: expr) => { {
+       ($self: ident, $peer_state_lock: expr, $peer_state: expr, $per_peer_state_lock: expr, $chan: expr) => { {
                let mut updates = $chan.monitor_updating_restored(&$self.logger,
                        &$self.node_signer, $self.genesis_hash, &$self.default_configuration,
                        $self.best_block.read().unwrap().height());
@@ -1794,7 +1868,7 @@ macro_rules! handle_monitor_update_completion {
 }
 
 macro_rules! handle_new_monitor_update {
-       ($self: ident, $update_res: expr, $update_id: expr, $peer_state_lock: expr, $peer_state: expr, $per_peer_state_lock: expr, $chan: expr, MANUALLY_REMOVING, $remove: expr) => { {
+       ($self: ident, $update_res: expr, $peer_state_lock: expr, $peer_state: expr, $per_peer_state_lock: expr, $chan: expr, _internal, $remove: expr, $completed: expr) => { {
                // update_maps_on_chan_removal needs to be able to take id_to_peer, so make sure we can in
                // any case so that it won't deadlock.
                debug_assert_ne!($self.id_to_peer.held_by_thread(), LockHeldState::HeldByThread);
@@ -1805,30 +1879,56 @@ macro_rules! handle_new_monitor_update {
                        ChannelMonitorUpdateStatus::InProgress => {
                                log_debug!($self.logger, "ChannelMonitor update for {} in flight, holding messages until the update completes.",
                                        log_bytes!($chan.context.channel_id()[..]));
-                               Ok(())
+                               Ok(false)
                        },
                        ChannelMonitorUpdateStatus::PermanentFailure => {
                                log_error!($self.logger, "Closing channel {} due to monitor update ChannelMonitorUpdateStatus::PermanentFailure",
                                        log_bytes!($chan.context.channel_id()[..]));
-                               update_maps_on_chan_removal!($self, $chan);
-                               let res: Result<(), _> = Err(MsgHandleErrInternal::from_finish_shutdown(
+                               update_maps_on_chan_removal!($self, &$chan.context);
+                               let res = Err(MsgHandleErrInternal::from_finish_shutdown(
                                        "ChannelMonitor storage failure".to_owned(), $chan.context.channel_id(),
-                                       $chan.context.get_user_id(), $chan.force_shutdown(false),
+                                       $chan.context.get_user_id(), $chan.context.force_shutdown(false),
                                        $self.get_channel_update_for_broadcast(&$chan).ok()));
                                $remove;
                                res
                        },
                        ChannelMonitorUpdateStatus::Completed => {
-                               $chan.complete_one_mon_update($update_id);
-                               if $chan.no_monitor_updates_pending() {
-                                       handle_monitor_update_completion!($self, $update_id, $peer_state_lock, $peer_state, $per_peer_state_lock, $chan);
-                               }
-                               Ok(())
+                               $completed;
+                               Ok(true)
                        },
                }
        } };
-       ($self: ident, $update_res: expr, $update_id: expr, $peer_state_lock: expr, $peer_state: expr, $per_peer_state_lock: expr, $chan_entry: expr) => {
-               handle_new_monitor_update!($self, $update_res, $update_id, $peer_state_lock, $peer_state, $per_peer_state_lock, $chan_entry.get_mut(), MANUALLY_REMOVING, $chan_entry.remove_entry())
+       ($self: ident, $update_res: expr, $peer_state_lock: expr, $peer_state: expr, $per_peer_state_lock: expr, $chan: expr, MANUALLY_REMOVING_INITIAL_MONITOR, $remove: expr) => {
+               handle_new_monitor_update!($self, $update_res, $peer_state_lock, $peer_state,
+                       $per_peer_state_lock, $chan, _internal, $remove,
+                       handle_monitor_update_completion!($self, $peer_state_lock, $peer_state, $per_peer_state_lock, $chan))
+       };
+       ($self: ident, $update_res: expr, $peer_state_lock: expr, $peer_state: expr, $per_peer_state_lock: expr, $chan_entry: expr, INITIAL_MONITOR) => {
+               handle_new_monitor_update!($self, $update_res, $peer_state_lock, $peer_state, $per_peer_state_lock, $chan_entry.get_mut(), MANUALLY_REMOVING_INITIAL_MONITOR, $chan_entry.remove_entry())
+       };
+       ($self: ident, $funding_txo: expr, $update: expr, $peer_state_lock: expr, $peer_state: expr, $per_peer_state_lock: expr, $chan: expr, MANUALLY_REMOVING, $remove: expr) => { {
+               let in_flight_updates = $peer_state.in_flight_monitor_updates.entry($funding_txo)
+                       .or_insert_with(Vec::new);
+               // During startup, we push monitor updates as background events through to here in
+               // order to replay updates that were in-flight when we shut down. Thus, we have to
+               // filter for uniqueness here.
+               let idx = in_flight_updates.iter().position(|upd| upd == &$update)
+                       .unwrap_or_else(|| {
+                               in_flight_updates.push($update);
+                               in_flight_updates.len() - 1
+                       });
+               let update_res = $self.chain_monitor.update_channel($funding_txo, &in_flight_updates[idx]);
+               handle_new_monitor_update!($self, update_res, $peer_state_lock, $peer_state,
+                       $per_peer_state_lock, $chan, _internal, $remove,
+                       {
+                               let _ = in_flight_updates.remove(idx);
+                               if in_flight_updates.is_empty() && $chan.blocked_monitor_updates_pending() == 0 {
+                                       handle_monitor_update_completion!($self, $peer_state_lock, $peer_state, $per_peer_state_lock, $chan);
+                               }
+                       })
+       } };
+       ($self: ident, $funding_txo: expr, $update: expr, $peer_state_lock: expr, $peer_state: expr, $per_peer_state_lock: expr, $chan_entry: expr) => {
+               handle_new_monitor_update!($self, $funding_txo, $update, $peer_state_lock, $peer_state, $per_peer_state_lock, $chan_entry.get_mut(), MANUALLY_REMOVING, $chan_entry.remove_entry())
        }
 }
 
@@ -2044,7 +2144,7 @@ where
                        let outbound_scid_alias = self.create_and_insert_outbound_scid_alias();
                        let their_features = &peer_state.latest_features;
                        let config = if override_config.is_some() { override_config.as_ref().unwrap() } else { &self.default_configuration };
-                       match Channel::new_outbound(&self.fee_estimator, &self.entropy_source, &self.signer_provider, their_network_key,
+                       match OutboundV1Channel::new(&self.fee_estimator, &self.entropy_source, &self.signer_provider, their_network_key,
                                their_features, channel_value_satoshis, push_msat, user_channel_id, config,
                                self.best_block.read().unwrap().height(), outbound_scid_alias)
                        {
@@ -2058,7 +2158,7 @@ where
                let res = channel.get_open_channel(self.genesis_hash.clone());
 
                let temporary_channel_id = channel.context.channel_id();
-               match peer_state.channel_by_id.entry(temporary_channel_id) {
+               match peer_state.outbound_v1_channel_by_id.entry(temporary_channel_id) {
                        hash_map::Entry::Occupied(_) => {
                                if cfg!(fuzzing) {
                                        return Err(APIError::APIMisuseError { err: "Fuzzy bad RNG".to_owned() });
@@ -2076,7 +2176,7 @@ where
                Ok(temporary_channel_id)
        }
 
-       fn list_channels_with_filter<Fn: FnMut(&(&[u8; 32], &Channel<<SP::Target as SignerProvider>::Signer>)) -> bool + Copy>(&self, f: Fn) -> Vec<ChannelDetails> {
+       fn list_funded_channels_with_filter<Fn: FnMut(&(&[u8; 32], &Channel<<SP::Target as SignerProvider>::Signer>)) -> bool + Copy>(&self, f: Fn) -> Vec<ChannelDetails> {
                // 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
@@ -2091,7 +2191,7 @@ where
                                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                                let peer_state = &mut *peer_state_lock;
                                for (_channel_id, channel) in peer_state.channel_by_id.iter().filter(f) {
-                                       let details = ChannelDetails::from_channel(channel, best_block_height,
+                                       let details = ChannelDetails::from_channel_context(&channel.context, best_block_height,
                                                peer_state.latest_features.clone());
                                        res.push(details);
                                }
@@ -2103,7 +2203,37 @@ where
        /// Gets the list of open channels, in random order. See [`ChannelDetails`] field documentation for
        /// more information.
        pub fn list_channels(&self) -> Vec<ChannelDetails> {
-               self.list_channels_with_filter(|_| true)
+               // 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.
+               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();
+                       for (_cp_id, 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;
+                               for (_channel_id, channel) in peer_state.channel_by_id.iter() {
+                                       let details = ChannelDetails::from_channel_context(&channel.context, best_block_height,
+                                               peer_state.latest_features.clone());
+                                       res.push(details);
+                               }
+                               for (_channel_id, channel) in peer_state.inbound_v1_channel_by_id.iter() {
+                                       let details = ChannelDetails::from_channel_context(&channel.context, best_block_height,
+                                               peer_state.latest_features.clone());
+                                       res.push(details);
+                               }
+                               for (_channel_id, channel) in peer_state.outbound_v1_channel_by_id.iter() {
+                                       let details = ChannelDetails::from_channel_context(&channel.context, best_block_height,
+                                               peer_state.latest_features.clone());
+                                       res.push(details);
+                               }
+                       }
+               }
+               res
        }
 
        /// Gets the list of usable channels, in random order. Useful as an argument to
@@ -2116,7 +2246,7 @@ where
                // Note we use is_live here instead of usable which leads to somewhat confused
                // internal/external nomenclature, but that's ok cause that's probably what the user
                // really wanted anyway.
-               self.list_channels_with_filter(|&(_, ref channel)| channel.context.is_live())
+               self.list_funded_channels_with_filter(|&(_, ref channel)| channel.context.is_live())
        }
 
        /// Gets the list of channels we have with a given counterparty, in random order.
@@ -2131,7 +2261,7 @@ where
                        return peer_state.channel_by_id
                                .iter()
                                .map(|(_, channel)|
-                                       ChannelDetails::from_channel(channel, best_block_height, features.clone()))
+                                       ChannelDetails::from_channel_context(&channel.context, best_block_height, features.clone()))
                                .collect();
                }
                vec![]
@@ -2166,19 +2296,19 @@ where
        }
 
        /// Helper function that issues the channel close events
-       fn issue_channel_close_events(&self, channel: &Channel<<SP::Target as SignerProvider>::Signer>, closure_reason: ClosureReason) {
+       fn issue_channel_close_events(&self, context: &ChannelContext<<SP::Target as SignerProvider>::Signer>, closure_reason: ClosureReason) {
                let mut pending_events_lock = self.pending_events.lock().unwrap();
-               match channel.unbroadcasted_funding() {
+               match context.unbroadcasted_funding() {
                        Some(transaction) => {
                                pending_events_lock.push_back((events::Event::DiscardFunding {
-                                       channel_id: channel.context.channel_id(), transaction
+                                       channel_id: context.channel_id(), transaction
                                }, None));
                        },
                        None => {},
                }
                pending_events_lock.push_back((events::Event::ChannelClosed {
-                       channel_id: channel.context.channel_id(),
-                       user_channel_id: channel.context.get_user_id(),
+                       channel_id: context.channel_id(),
+                       user_channel_id: context.get_user_id(),
                        reason: closure_reason
                }, None));
        }
@@ -2213,9 +2343,8 @@ where
 
                                        // Update the monitor with the shutdown script if necessary.
                                        if let Some(monitor_update) = monitor_update_opt.take() {
-                                               let update_id = monitor_update.update_id;
-                                               let update_res = self.chain_monitor.update_channel(funding_txo_opt.unwrap(), monitor_update);
-                                               break handle_new_monitor_update!(self, update_res, update_id, peer_state_lock, peer_state, per_peer_state, chan_entry);
+                                               break handle_new_monitor_update!(self, funding_txo_opt.unwrap(), monitor_update,
+                                                       peer_state_lock, peer_state, per_peer_state, chan_entry).map(|_| ());
                                        }
 
                                        if chan_entry.get().is_shutdown() {
@@ -2225,7 +2354,7 @@ where
                                                                msg: channel_update
                                                        });
                                                }
-                                               self.issue_channel_close_events(&channel, ClosureReason::HolderForceClosed);
+                                               self.issue_channel_close_events(&channel.context, ClosureReason::HolderForceClosed);
                                        }
                                        break Ok(());
                                },
@@ -2330,30 +2459,46 @@ where
                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::ChannelUnavailable { err: format!("Can't find a peer matching the passed counterparty node_id {}", peer_node_id) })?;
-               let mut chan = {
+               let (update_opt, counterparty_node_id) = {
                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
+                       let closure_reason = if let Some(peer_msg) = peer_msg {
+                               ClosureReason::CounterpartyForceClosed { peer_msg: UntrustedString(peer_msg.to_string()) }
+                       } else {
+                               ClosureReason::HolderForceClosed
+                       };
                        if let hash_map::Entry::Occupied(chan) = peer_state.channel_by_id.entry(channel_id.clone()) {
-                               if let Some(peer_msg) = peer_msg {
-                                       self.issue_channel_close_events(chan.get(),ClosureReason::CounterpartyForceClosed { peer_msg: UntrustedString(peer_msg.to_string()) });
-                               } else {
-                                       self.issue_channel_close_events(chan.get(),ClosureReason::HolderForceClosed);
-                               }
-                               remove_channel!(self, chan)
+                               log_error!(self.logger, "Force-closing channel {}", log_bytes!(channel_id[..]));
+                               self.issue_channel_close_events(&chan.get().context, closure_reason);
+                               let mut chan = remove_channel!(self, chan);
+                               self.finish_force_close_channel(chan.context.force_shutdown(broadcast));
+                               (self.get_channel_update_for_broadcast(&chan).ok(), chan.context.get_counterparty_node_id())
+                       } else if let hash_map::Entry::Occupied(chan) = peer_state.outbound_v1_channel_by_id.entry(channel_id.clone()) {
+                               log_error!(self.logger, "Force-closing channel {}", log_bytes!(channel_id[..]));
+                               self.issue_channel_close_events(&chan.get().context, closure_reason);
+                               let mut chan = remove_channel!(self, chan);
+                               self.finish_force_close_channel(chan.context.force_shutdown(false));
+                               // Prefunded channel has no update
+                               (None, chan.context.get_counterparty_node_id())
+                       } else if let hash_map::Entry::Occupied(chan) = peer_state.inbound_v1_channel_by_id.entry(channel_id.clone()) {
+                               log_error!(self.logger, "Force-closing channel {}", log_bytes!(channel_id[..]));
+                               self.issue_channel_close_events(&chan.get().context, closure_reason);
+                               let mut chan = remove_channel!(self, chan);
+                               self.finish_force_close_channel(chan.context.force_shutdown(false));
+                               // Prefunded channel has no update
+                               (None, chan.context.get_counterparty_node_id())
                        } else {
                                return Err(APIError::ChannelUnavailable{ err: format!("Channel with id {} not found for the passed counterparty node_id {}", log_bytes!(*channel_id), peer_node_id) });
                        }
                };
-               log_error!(self.logger, "Force-closing channel {}", log_bytes!(channel_id[..]));
-               self.finish_force_close_channel(chan.force_shutdown(broadcast));
-               if let Ok(update) = self.get_channel_update_for_broadcast(&chan) {
+               if let Some(update) = update_opt {
                        let mut peer_state = peer_state_mutex.lock().unwrap();
                        peer_state.pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
                                msg: update
                        });
                }
 
-               Ok(chan.context.get_counterparty_node_id())
+               Ok(counterparty_node_id)
        }
 
        fn force_close_sending_error(&self, channel_id: &[u8; 32], counterparty_node_id: &PublicKey, broadcast: bool) -> Result<(), APIError> {
@@ -2414,9 +2559,11 @@ where
                }
        }
 
-       fn construct_recv_pending_htlc_info(&self, hop_data: msgs::OnionHopData, shared_secret: [u8; 32],
-               payment_hash: PaymentHash, amt_msat: u64, cltv_expiry: u32, phantom_shared_secret: Option<[u8; 32]>) -> Result<PendingHTLCInfo, ReceiveError>
-       {
+       fn construct_recv_pending_htlc_info(
+               &self, hop_data: msgs::OnionHopData, shared_secret: [u8; 32], payment_hash: PaymentHash,
+               amt_msat: u64, cltv_expiry: u32, phantom_shared_secret: Option<[u8; 32]>, allow_underpay: bool,
+               counterparty_skimmed_fee_msat: Option<u64>,
+       ) -> Result<PendingHTLCInfo, ReceiveError> {
                // final_incorrect_cltv_expiry
                if hop_data.outgoing_cltv_value > cltv_expiry {
                        return Err(ReceiveError {
@@ -2442,7 +2589,10 @@ where
                                msg: "The final CLTV expiry is too soon to handle",
                        });
                }
-               if hop_data.amt_to_forward > amt_msat {
+               if (!allow_underpay && hop_data.amt_to_forward > amt_msat) ||
+                       (allow_underpay && hop_data.amt_to_forward >
+                        amt_msat.saturating_add(counterparty_skimmed_fee_msat.unwrap_or(0)))
+               {
                        return Err(ReceiveError {
                                err_code: 19,
                                err_data: amt_msat.to_be_bytes().to_vec(),
@@ -2509,15 +2659,18 @@ where
                        incoming_amt_msat: Some(amt_msat),
                        outgoing_amt_msat: hop_data.amt_to_forward,
                        outgoing_cltv_value: hop_data.outgoing_cltv_value,
+                       skimmed_fee_msat: counterparty_skimmed_fee_msat,
                })
        }
 
-       fn decode_update_add_htlc_onion(&self, msg: &msgs::UpdateAddHTLC) -> PendingHTLCStatus {
+       fn decode_update_add_htlc_onion(
+               &self, msg: &msgs::UpdateAddHTLC
+       ) -> Result<(onion_utils::Hop, [u8; 32], Option<Result<PublicKey, secp256k1::Error>>), HTLCFailureMsg> {
                macro_rules! return_malformed_err {
                        ($msg: expr, $err_code: expr) => {
                                {
                                        log_info!(self.logger, "Failed to accept/forward incoming HTLC: {}", $msg);
-                                       return PendingHTLCStatus::Fail(HTLCFailureMsg::Malformed(msgs::UpdateFailMalformedHTLC {
+                                       return Err(HTLCFailureMsg::Malformed(msgs::UpdateFailMalformedHTLC {
                                                channel_id: msg.channel_id,
                                                htlc_id: msg.htlc_id,
                                                sha256_of_onion: Sha256::hash(&msg.onion_routing_packet.hop_data).into_inner(),
@@ -2548,7 +2701,7 @@ where
                        ($msg: expr, $err_code: expr, $data: expr) => {
                                {
                                        log_info!(self.logger, "Failed to accept/forward incoming HTLC: {}", $msg);
-                                       return PendingHTLCStatus::Fail(HTLCFailureMsg::Relay(msgs::UpdateFailHTLC {
+                                       return Err(HTLCFailureMsg::Relay(msgs::UpdateFailHTLC {
                                                channel_id: msg.channel_id,
                                                htlc_id: msg.htlc_id,
                                                reason: HTLCFailReason::reason($err_code, $data.to_vec())
@@ -2567,11 +2720,186 @@ where
                                return_err!(err_msg, err_code, &[0; 0]);
                        },
                };
+               let (outgoing_scid, outgoing_amt_msat, outgoing_cltv_value, next_packet_pk_opt) = match next_hop {
+                       onion_utils::Hop::Forward {
+                               next_hop_data: msgs::OnionHopData {
+                                       format: msgs::OnionHopDataFormat::NonFinalNode { short_channel_id }, amt_to_forward,
+                                       outgoing_cltv_value,
+                               }, ..
+                       } => {
+                               let next_pk = onion_utils::next_hop_packet_pubkey(&self.secp_ctx,
+                                       msg.onion_routing_packet.public_key.unwrap(), &shared_secret);
+                               (short_channel_id, amt_to_forward, outgoing_cltv_value, Some(next_pk))
+                       },
+                       // We'll do receive checks in [`Self::construct_pending_htlc_info`] so we have access to the
+                       // inbound channel's state.
+                       onion_utils::Hop::Receive { .. } => return Ok((next_hop, shared_secret, None)),
+                       onion_utils::Hop::Forward {
+                               next_hop_data: msgs::OnionHopData { format: msgs::OnionHopDataFormat::FinalNode { .. }, .. }, ..
+                       } => {
+                               return_err!("Final Node OnionHopData provided for us as an intermediary node", 0x4000 | 22, &[0; 0]);
+                       }
+               };
 
-               let pending_forward_info = match next_hop {
+               // Perform outbound checks here instead of in [`Self::construct_pending_htlc_info`] because we
+               // can't hold the outbound peer state lock at the same time as the inbound peer state lock.
+               if let Some((err, mut code, chan_update)) = loop {
+                       let id_option = self.short_to_chan_info.read().unwrap().get(&outgoing_scid).cloned();
+                       let forwarding_chan_info_opt = match id_option {
+                               None => { // unknown_next_peer
+                                       // Note that this is likely a timing oracle for detecting whether an scid is a
+                                       // phantom or an intercept.
+                                       if (self.default_configuration.accept_intercept_htlcs &&
+                                               fake_scid::is_valid_intercept(&self.fake_scid_rand_bytes, outgoing_scid, &self.genesis_hash)) ||
+                                               fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, outgoing_scid, &self.genesis_hash)
+                                       {
+                                               None
+                                       } else {
+                                               break Some(("Don't have available channel for forwarding as requested.", 0x4000 | 10, None));
+                                       }
+                               },
+                               Some((cp_id, id)) => Some((cp_id.clone(), id.clone())),
+                       };
+                       let chan_update_opt = if let Some((counterparty_node_id, forwarding_id)) = forwarding_chan_info_opt {
+                               let per_peer_state = self.per_peer_state.read().unwrap();
+                               let peer_state_mutex_opt = per_peer_state.get(&counterparty_node_id);
+                               if peer_state_mutex_opt.is_none() {
+                                       break Some(("Don't have available channel for forwarding as requested.", 0x4000 | 10, None));
+                               }
+                               let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
+                               let peer_state = &mut *peer_state_lock;
+                               let chan = match peer_state.channel_by_id.get_mut(&forwarding_id) {
+                                       None => {
+                                               // Channel was removed. The short_to_chan_info and channel_by_id maps
+                                               // have no consistency guarantees.
+                                               break Some(("Don't have available channel for forwarding as requested.", 0x4000 | 10, None));
+                                       },
+                                       Some(chan) => chan
+                               };
+                               if !chan.context.should_announce() && !self.default_configuration.accept_forwards_to_priv_channels {
+                                       // Note that the behavior here should be identical to the above block - we
+                                       // should NOT reveal the existence or non-existence of a private channel if
+                                       // we don't allow forwards outbound over them.
+                                       break Some(("Refusing to forward to a private channel based on our config.", 0x4000 | 10, None));
+                               }
+                               if chan.context.get_channel_type().supports_scid_privacy() && outgoing_scid != chan.context.outbound_scid_alias() {
+                                       // `option_scid_alias` (referred to in LDK as `scid_privacy`) means
+                                       // "refuse to forward unless the SCID alias was used", so we pretend
+                                       // we don't have the channel here.
+                                       break Some(("Refusing to forward over real channel SCID as our counterparty requested.", 0x4000 | 10, None));
+                               }
+                               let chan_update_opt = self.get_channel_update_for_onion(outgoing_scid, chan).ok();
+
+                               // Note that we could technically not return an error yet here and just hope
+                               // that the connection is reestablished or monitor updated by the time we get
+                               // around to doing the actual forward, but better to fail early if we can and
+                               // hopefully an attacker trying to path-trace payments cannot make this occur
+                               // on a small/per-node/per-channel scale.
+                               if !chan.context.is_live() { // channel_disabled
+                                       // If the channel_update we're going to return is disabled (i.e. the
+                                       // peer has been disabled for some time), return `channel_disabled`,
+                                       // otherwise return `temporary_channel_failure`.
+                                       if chan_update_opt.as_ref().map(|u| u.contents.flags & 2 == 2).unwrap_or(false) {
+                                               break Some(("Forwarding channel has been disconnected for some time.", 0x1000 | 20, chan_update_opt));
+                                       } else {
+                                               break Some(("Forwarding channel is not in a ready state.", 0x1000 | 7, chan_update_opt));
+                                       }
+                               }
+                               if outgoing_amt_msat < chan.context.get_counterparty_htlc_minimum_msat() { // amount_below_minimum
+                                       break Some(("HTLC amount was below the htlc_minimum_msat", 0x1000 | 11, chan_update_opt));
+                               }
+                               if let Err((err, code)) = chan.htlc_satisfies_config(&msg, outgoing_amt_msat, outgoing_cltv_value) {
+                                       break Some((err, code, chan_update_opt));
+                               }
+                               chan_update_opt
+                       } else {
+                               if (msg.cltv_expiry as u64) < (outgoing_cltv_value) as u64 + MIN_CLTV_EXPIRY_DELTA as u64 {
+                                       // We really should set `incorrect_cltv_expiry` here but as we're not
+                                       // forwarding over a real channel we can't generate a channel_update
+                                       // for it. Instead we just return a generic temporary_node_failure.
+                                       break Some((
+                                                       "Forwarding node has tampered with the intended HTLC values or origin node has an obsolete cltv_expiry_delta",
+                                                       0x2000 | 2, None,
+                                       ));
+                               }
+                               None
+                       };
+
+                       let cur_height = self.best_block.read().unwrap().height() + 1;
+                       // Theoretically, channel counterparty shouldn't send us a HTLC expiring now,
+                       // but we want to be robust wrt to counterparty packet sanitization (see
+                       // HTLC_FAIL_BACK_BUFFER rationale).
+                       if msg.cltv_expiry <= cur_height + HTLC_FAIL_BACK_BUFFER as u32 { // expiry_too_soon
+                               break Some(("CLTV expiry is too close", 0x1000 | 14, chan_update_opt));
+                       }
+                       if msg.cltv_expiry > cur_height + CLTV_FAR_FAR_AWAY as u32 { // expiry_too_far
+                               break Some(("CLTV expiry is too far in the future", 21, None));
+                       }
+                       // If the HTLC expires ~now, don't bother trying to forward it to our
+                       // counterparty. They should fail it anyway, but we don't want to bother with
+                       // the round-trips or risk them deciding they definitely want the HTLC and
+                       // force-closing to ensure they get it if we're offline.
+                       // We previously had a much more aggressive check here which tried to ensure
+                       // our counterparty receives an HTLC which has *our* risk threshold met on it,
+                       // but there is no need to do that, and since we're a bit conservative with our
+                       // risk threshold it just results in failing to forward payments.
+                       if (outgoing_cltv_value) as u64 <= (cur_height + LATENCY_GRACE_PERIOD_BLOCKS) as u64 {
+                               break Some(("Outgoing CLTV value is too soon", 0x1000 | 14, chan_update_opt));
+                       }
+
+                       break None;
+               }
+               {
+                       let mut res = VecWriter(Vec::with_capacity(chan_update.serialized_length() + 2 + 8 + 2));
+                       if let Some(chan_update) = chan_update {
+                               if code == 0x1000 | 11 || code == 0x1000 | 12 {
+                                       msg.amount_msat.write(&mut res).expect("Writes cannot fail");
+                               }
+                               else if code == 0x1000 | 13 {
+                                       msg.cltv_expiry.write(&mut res).expect("Writes cannot fail");
+                               }
+                               else if code == 0x1000 | 20 {
+                                       // TODO: underspecified, follow https://github.com/lightning/bolts/issues/791
+                                       0u16.write(&mut res).expect("Writes cannot fail");
+                               }
+                               (chan_update.serialized_length() as u16 + 2).write(&mut res).expect("Writes cannot fail");
+                               msgs::ChannelUpdate::TYPE.write(&mut res).expect("Writes cannot fail");
+                               chan_update.write(&mut res).expect("Writes cannot fail");
+                       } else if code & 0x1000 == 0x1000 {
+                               // If we're trying to return an error that requires a `channel_update` but
+                               // we're forwarding to a phantom or intercept "channel" (i.e. cannot
+                               // generate an update), just use the generic "temporary_node_failure"
+                               // instead.
+                               code = 0x2000 | 2;
+                       }
+                       return_err!(err, code, &res.0[..]);
+               }
+               Ok((next_hop, shared_secret, next_packet_pk_opt))
+       }
+
+       fn construct_pending_htlc_status<'a>(
+               &self, msg: &msgs::UpdateAddHTLC, shared_secret: [u8; 32], decoded_hop: onion_utils::Hop,
+               allow_underpay: bool, next_packet_pubkey_opt: Option<Result<PublicKey, secp256k1::Error>>
+       ) -> PendingHTLCStatus {
+               macro_rules! return_err {
+                       ($msg: expr, $err_code: expr, $data: expr) => {
+                               {
+                                       log_info!(self.logger, "Failed to accept/forward incoming HTLC: {}", $msg);
+                                       return PendingHTLCStatus::Fail(HTLCFailureMsg::Relay(msgs::UpdateFailHTLC {
+                                               channel_id: msg.channel_id,
+                                               htlc_id: msg.htlc_id,
+                                               reason: HTLCFailReason::reason($err_code, $data.to_vec())
+                                                       .get_encrypted_failure_packet(&shared_secret, &None),
+                                       }));
+                               }
+                       }
+               }
+               match decoded_hop {
                        onion_utils::Hop::Receive(next_hop_data) => {
                                // OUR PAYMENT!
-                               match self.construct_recv_pending_htlc_info(next_hop_data, shared_secret, msg.payment_hash, msg.amount_msat, msg.cltv_expiry, None) {
+                               match self.construct_recv_pending_htlc_info(next_hop_data, shared_secret, msg.payment_hash,
+                                       msg.amount_msat, msg.cltv_expiry, None, allow_underpay, msg.skimmed_fee_msat)
+                               {
                                        Ok(info) => {
                                                // Note that we could obviously respond immediately with an update_fulfill_htlc
                                                // message, however that would leak that we are the recipient of this payment, so
@@ -2583,10 +2911,10 @@ where
                                }
                        },
                        onion_utils::Hop::Forward { next_hop_data, next_hop_hmac, new_packet_bytes } => {
-                               let new_pubkey = msg.onion_routing_packet.public_key.unwrap();
+                               debug_assert!(next_packet_pubkey_opt.is_some());
                                let outgoing_packet = msgs::OnionPacket {
                                        version: 0,
-                                       public_key: onion_utils::next_hop_packet_pubkey(&self.secp_ctx, new_pubkey, &shared_secret),
+                                       public_key: next_packet_pubkey_opt.unwrap_or(Err(secp256k1::Error::InvalidPublicKey)),
                                        hop_data: new_packet_bytes,
                                        hmac: next_hop_hmac.clone(),
                                };
@@ -2608,150 +2936,10 @@ where
                                        incoming_amt_msat: Some(msg.amount_msat),
                                        outgoing_amt_msat: next_hop_data.amt_to_forward,
                                        outgoing_cltv_value: next_hop_data.outgoing_cltv_value,
+                                       skimmed_fee_msat: None,
                                })
                        }
-               };
-
-               if let &PendingHTLCStatus::Forward(PendingHTLCInfo { ref routing, ref outgoing_amt_msat, ref outgoing_cltv_value, .. }) = &pending_forward_info {
-                       // If short_channel_id is 0 here, we'll reject the HTLC as there cannot be a channel
-                       // with a short_channel_id of 0. This is important as various things later assume
-                       // short_channel_id is non-0 in any ::Forward.
-                       if let &PendingHTLCRouting::Forward { ref short_channel_id, .. } = routing {
-                               if let Some((err, mut code, chan_update)) = loop {
-                                       let id_option = self.short_to_chan_info.read().unwrap().get(short_channel_id).cloned();
-                                       let forwarding_chan_info_opt = match id_option {
-                                               None => { // unknown_next_peer
-                                                       // Note that this is likely a timing oracle for detecting whether an scid is a
-                                                       // phantom or an intercept.
-                                                       if (self.default_configuration.accept_intercept_htlcs &&
-                                                          fake_scid::is_valid_intercept(&self.fake_scid_rand_bytes, *short_channel_id, &self.genesis_hash)) ||
-                                                          fake_scid::is_valid_phantom(&self.fake_scid_rand_bytes, *short_channel_id, &self.genesis_hash)
-                                                       {
-                                                               None
-                                                       } else {
-                                                               break Some(("Don't have available channel for forwarding as requested.", 0x4000 | 10, None));
-                                                       }
-                                               },
-                                               Some((cp_id, id)) => Some((cp_id.clone(), id.clone())),
-                                       };
-                                       let chan_update_opt = if let Some((counterparty_node_id, forwarding_id)) = forwarding_chan_info_opt {
-                                               let per_peer_state = self.per_peer_state.read().unwrap();
-                                               let peer_state_mutex_opt = per_peer_state.get(&counterparty_node_id);
-                                               if peer_state_mutex_opt.is_none() {
-                                                       break Some(("Don't have available channel for forwarding as requested.", 0x4000 | 10, None));
-                                               }
-                                               let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
-                                               let peer_state = &mut *peer_state_lock;
-                                               let chan = match peer_state.channel_by_id.get_mut(&forwarding_id) {
-                                                       None => {
-                                                               // Channel was removed. The short_to_chan_info and channel_by_id maps
-                                                               // have no consistency guarantees.
-                                                               break Some(("Don't have available channel for forwarding as requested.", 0x4000 | 10, None));
-                                                       },
-                                                       Some(chan) => chan
-                                               };
-                                               if !chan.context.should_announce() && !self.default_configuration.accept_forwards_to_priv_channels {
-                                                       // Note that the behavior here should be identical to the above block - we
-                                                       // should NOT reveal the existence or non-existence of a private channel if
-                                                       // we don't allow forwards outbound over them.
-                                                       break Some(("Refusing to forward to a private channel based on our config.", 0x4000 | 10, None));
-                                               }
-                                               if chan.context.get_channel_type().supports_scid_privacy() && *short_channel_id != chan.context.outbound_scid_alias() {
-                                                       // `option_scid_alias` (referred to in LDK as `scid_privacy`) means
-                                                       // "refuse to forward unless the SCID alias was used", so we pretend
-                                                       // we don't have the channel here.
-                                                       break Some(("Refusing to forward over real channel SCID as our counterparty requested.", 0x4000 | 10, None));
-                                               }
-                                               let chan_update_opt = self.get_channel_update_for_onion(*short_channel_id, chan).ok();
-
-                                               // Note that we could technically not return an error yet here and just hope
-                                               // that the connection is reestablished or monitor updated by the time we get
-                                               // around to doing the actual forward, but better to fail early if we can and
-                                               // hopefully an attacker trying to path-trace payments cannot make this occur
-                                               // on a small/per-node/per-channel scale.
-                                               if !chan.context.is_live() { // channel_disabled
-                                                       // If the channel_update we're going to return is disabled (i.e. the
-                                                       // peer has been disabled for some time), return `channel_disabled`,
-                                                       // otherwise return `temporary_channel_failure`.
-                                                       if chan_update_opt.as_ref().map(|u| u.contents.flags & 2 == 2).unwrap_or(false) {
-                                                               break Some(("Forwarding channel has been disconnected for some time.", 0x1000 | 20, chan_update_opt));
-                                                       } else {
-                                                               break Some(("Forwarding channel is not in a ready state.", 0x1000 | 7, chan_update_opt));
-                                                       }
-                                               }
-                                               if *outgoing_amt_msat < chan.context.get_counterparty_htlc_minimum_msat() { // amount_below_minimum
-                                                       break Some(("HTLC amount was below the htlc_minimum_msat", 0x1000 | 11, chan_update_opt));
-                                               }
-                                               if let Err((err, code)) = chan.htlc_satisfies_config(&msg, *outgoing_amt_msat, *outgoing_cltv_value) {
-                                                       break Some((err, code, chan_update_opt));
-                                               }
-                                               chan_update_opt
-                                       } else {
-                                               if (msg.cltv_expiry as u64) < (*outgoing_cltv_value) as u64 + MIN_CLTV_EXPIRY_DELTA as u64 {
-                                                       // We really should set `incorrect_cltv_expiry` here but as we're not
-                                                       // forwarding over a real channel we can't generate a channel_update
-                                                       // for it. Instead we just return a generic temporary_node_failure.
-                                                       break Some((
-                                                               "Forwarding node has tampered with the intended HTLC values or origin node has an obsolete cltv_expiry_delta",
-                                                               0x2000 | 2, None,
-                                                       ));
-                                               }
-                                               None
-                                       };
-
-                                       let cur_height = self.best_block.read().unwrap().height() + 1;
-                                       // Theoretically, channel counterparty shouldn't send us a HTLC expiring now,
-                                       // but we want to be robust wrt to counterparty packet sanitization (see
-                                       // HTLC_FAIL_BACK_BUFFER rationale).
-                                       if msg.cltv_expiry <= cur_height + HTLC_FAIL_BACK_BUFFER as u32 { // expiry_too_soon
-                                               break Some(("CLTV expiry is too close", 0x1000 | 14, chan_update_opt));
-                                       }
-                                       if msg.cltv_expiry > cur_height + CLTV_FAR_FAR_AWAY as u32 { // expiry_too_far
-                                               break Some(("CLTV expiry is too far in the future", 21, None));
-                                       }
-                                       // If the HTLC expires ~now, don't bother trying to forward it to our
-                                       // counterparty. They should fail it anyway, but we don't want to bother with
-                                       // the round-trips or risk them deciding they definitely want the HTLC and
-                                       // force-closing to ensure they get it if we're offline.
-                                       // We previously had a much more aggressive check here which tried to ensure
-                                       // our counterparty receives an HTLC which has *our* risk threshold met on it,
-                                       // but there is no need to do that, and since we're a bit conservative with our
-                                       // risk threshold it just results in failing to forward payments.
-                                       if (*outgoing_cltv_value) as u64 <= (cur_height + LATENCY_GRACE_PERIOD_BLOCKS) as u64 {
-                                               break Some(("Outgoing CLTV value is too soon", 0x1000 | 14, chan_update_opt));
-                                       }
-
-                                       break None;
-                               }
-                               {
-                                       let mut res = VecWriter(Vec::with_capacity(chan_update.serialized_length() + 2 + 8 + 2));
-                                       if let Some(chan_update) = chan_update {
-                                               if code == 0x1000 | 11 || code == 0x1000 | 12 {
-                                                       msg.amount_msat.write(&mut res).expect("Writes cannot fail");
-                                               }
-                                               else if code == 0x1000 | 13 {
-                                                       msg.cltv_expiry.write(&mut res).expect("Writes cannot fail");
-                                               }
-                                               else if code == 0x1000 | 20 {
-                                                       // TODO: underspecified, follow https://github.com/lightning/bolts/issues/791
-                                                       0u16.write(&mut res).expect("Writes cannot fail");
-                                               }
-                                               (chan_update.serialized_length() as u16 + 2).write(&mut res).expect("Writes cannot fail");
-                                               msgs::ChannelUpdate::TYPE.write(&mut res).expect("Writes cannot fail");
-                                               chan_update.write(&mut res).expect("Writes cannot fail");
-                                       } else if code & 0x1000 == 0x1000 {
-                                               // If we're trying to return an error that requires a `channel_update` but
-                                               // we're forwarding to a phantom or intercept "channel" (i.e. cannot
-                                               // generate an update), just use the generic "temporary_node_failure"
-                                               // instead.
-                                               code = 0x2000 | 2;
-                                       }
-                                       return_err!(err, code, &res.0[..]);
-                               }
-                       }
                }
-
-               pending_forward_info
        }
 
        /// Gets the current [`channel_update`] for the given channel. This first checks if the channel is
@@ -2798,6 +2986,7 @@ where
 
                self.get_channel_update_for_onion(short_channel_id, chan)
        }
+
        fn get_channel_update_for_onion(&self, short_channel_id: u64, chan: &Channel<<SP::Target as SignerProvider>::Signer>) -> Result<msgs::ChannelUpdate, LightningError> {
                log_trace!(self.logger, "Generating channel update for channel {}", log_bytes!(chan.context.channel_id()));
                let were_node_one = self.our_network_pubkey.serialize()[..] < chan.context.get_counterparty_node_id().serialize()[..];
@@ -2876,22 +3065,21 @@ where
                                                session_priv: session_priv.clone(),
                                                first_hop_htlc_msat: htlc_msat,
                                                payment_id,
-                                       }, onion_packet, &self.logger);
+                                       }, onion_packet, None, &self.logger);
                                match break_chan_entry!(self, send_res, chan) {
                                        Some(monitor_update) => {
-                                               let update_id = monitor_update.update_id;
-                                               let update_res = self.chain_monitor.update_channel(funding_txo, monitor_update);
-                                               if let Err(e) = handle_new_monitor_update!(self, update_res, update_id, peer_state_lock, peer_state, per_peer_state, chan) {
-                                                       break Err(e);
-                                               }
-                                               if update_res == ChannelMonitorUpdateStatus::InProgress {
-                                                       // Note that MonitorUpdateInProgress here indicates (per function
-                                                       // docs) that we will resend the commitment update once monitor
-                                                       // updating completes. Therefore, we must return an error
-                                                       // indicating that it is unsafe to retry the payment wholesale,
-                                                       // which we do in the send_payment check for
-                                                       // MonitorUpdateInProgress, below.
-                                                       return Err(APIError::MonitorUpdateInProgress);
+                                               match handle_new_monitor_update!(self, funding_txo, monitor_update, peer_state_lock, peer_state, per_peer_state, chan) {
+                                                       Err(e) => break Err(e),
+                                                       Ok(false) => {
+                                                               // Note that MonitorUpdateInProgress here indicates (per function
+                                                               // docs) that we will resend the commitment update once monitor
+                                                               // updating completes. Therefore, we must return an error
+                                                               // indicating that it is unsafe to retry the payment wholesale,
+                                                               // which we do in the send_payment check for
+                                                               // MonitorUpdateInProgress, below.
+                                                               return Err(APIError::MonitorUpdateInProgress);
+                                                       },
+                                                       Ok(true) => {},
                                                }
                                        },
                                        None => { },
@@ -3091,7 +3279,7 @@ where
 
        /// Handles the generation of a funding transaction, optionally (for tests) with a function
        /// which checks the correctness of the funding transaction given the associated channel.
-       fn funding_transaction_generated_intern<FundingOutput: Fn(&Channel<<SP::Target as SignerProvider>::Signer>, &Transaction) -> Result<OutPoint, APIError>>(
+       fn funding_transaction_generated_intern<FundingOutput: Fn(&OutboundV1Channel<<SP::Target as SignerProvider>::Signer>, &Transaction) -> Result<OutPoint, APIError>>(
                &self, temporary_channel_id: &[u8; 32], counterparty_node_id: &PublicKey, funding_transaction: Transaction, find_funding_output: FundingOutput
        ) -> Result<(), APIError> {
                let per_peer_state = self.per_peer_state.read().unwrap();
@@ -3100,21 +3288,24 @@ where
 
                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
-               let (msg, chan) = match peer_state.channel_by_id.remove(temporary_channel_id) {
-                       Some(mut chan) => {
+               let (chan, msg) = match peer_state.outbound_v1_channel_by_id.remove(temporary_channel_id) {
+                       Some(chan) => {
                                let funding_txo = find_funding_output(&chan, &funding_transaction)?;
 
                                let funding_res = chan.get_outbound_funding_created(funding_transaction, funding_txo, &self.logger)
-                                       .map_err(|e| if let ChannelError::Close(msg) = e {
-                                               MsgHandleErrInternal::from_finish_shutdown(msg, chan.context.channel_id(), chan.context.get_user_id(), chan.force_shutdown(true), None)
+                                       .map_err(|(mut chan, e)| if let ChannelError::Close(msg) = e {
+                                               let channel_id = chan.context.channel_id();
+                                               let user_id = chan.context.get_user_id();
+                                               let shutdown_res = chan.context.force_shutdown(false);
+                                               (chan, MsgHandleErrInternal::from_finish_shutdown(msg, channel_id, user_id, shutdown_res, None))
                                        } else { unreachable!(); });
                                match funding_res {
-                                       Ok(funding_msg) => (funding_msg, chan),
-                                       Err(_) => {
+                                       Ok((chan, funding_msg)) => (chan, funding_msg),
+                                       Err((chan, err)) => {
                                                mem::drop(peer_state_lock);
                                                mem::drop(per_peer_state);
 
-                                               let _ = handle_error!(self, funding_res, chan.context.get_counterparty_node_id());
+                                               let _: Result<(), _> = handle_error!(self, Err(err), chan.context.get_counterparty_node_id());
                                                return Err(APIError::ChannelUnavailable {
                                                        err: "Signer refused to sign the initial commitment transaction".to_owned()
                                                });
@@ -3340,13 +3531,16 @@ where
        /// [`ChannelManager::fail_intercepted_htlc`] MUST be called in response to the event.
        ///
        /// Note that LDK does not enforce fee requirements in `amt_to_forward_msat`, and will not stop
-       /// you from forwarding more than you received.
+       /// you from forwarding more than you received. See
+       /// [`HTLCIntercepted::expected_outbound_amount_msat`] for more on forwarding a different amount
+       /// than expected.
        ///
        /// Errors if the event was not handled in time, in which case the HTLC was automatically failed
        /// backwards.
        ///
        /// [`UserConfig::accept_intercept_htlcs`]: crate::util::config::UserConfig::accept_intercept_htlcs
        /// [`HTLCIntercepted`]: events::Event::HTLCIntercepted
+       /// [`HTLCIntercepted::expected_outbound_amount_msat`]: events::Event::HTLCIntercepted::expected_outbound_amount_msat
        // TODO: when we move to deciding the best outbound channel at forward time, only take
        // `next_node_id` and not `next_hop_channel_id`
        pub fn forward_intercepted_htlc(&self, intercept_id: InterceptId, next_hop_channel_id: &[u8; 32], next_node_id: PublicKey, amt_to_forward_msat: u64) -> Result<(), APIError> {
@@ -3368,7 +3562,8 @@ where
                                        chan.context.get_short_channel_id().unwrap_or(chan.context.outbound_scid_alias())
                                },
                                None => return Err(APIError::ChannelUnavailable {
-                                       err: format!("Channel with id {} not found for the passed counterparty node_id {}", log_bytes!(*next_hop_channel_id), next_node_id)
+                                       err: format!("Funded channel with id {} not found for the passed counterparty node_id {}. Channel may still be opening.",
+                                               log_bytes!(*next_hop_channel_id), next_node_id)
                                })
                        }
                };
@@ -3384,7 +3579,10 @@ where
                        },
                        _ => unreachable!() // Only `PendingHTLCRouting::Forward`s are intercepted
                };
+               let skimmed_fee_msat =
+                       payment.forward_info.outgoing_amt_msat.saturating_sub(amt_to_forward_msat);
                let pending_htlc_info = PendingHTLCInfo {
+                       skimmed_fee_msat: if skimmed_fee_msat == 0 { None } else { Some(skimmed_fee_msat) },
                        outgoing_amt_msat: amt_to_forward_msat, routing, ..payment.forward_info
                };
 
@@ -3454,7 +3652,7 @@ where
                                                                                prev_short_channel_id, prev_htlc_id, prev_funding_outpoint, prev_user_channel_id,
                                                                                forward_info: PendingHTLCInfo {
                                                                                        routing, incoming_shared_secret, payment_hash, outgoing_amt_msat,
-                                                                                       outgoing_cltv_value, incoming_amt_msat: _
+                                                                                       outgoing_cltv_value, ..
                                                                                }
                                                                        }) => {
                                                                                macro_rules! failure_handler {
@@ -3516,7 +3714,10 @@ where
                                                                                                };
                                                                                                match next_hop {
                                                                                                        onion_utils::Hop::Receive(hop_data) => {
-                                                                                                               match self.construct_recv_pending_htlc_info(hop_data, incoming_shared_secret, payment_hash, outgoing_amt_msat, outgoing_cltv_value, Some(phantom_shared_secret)) {
+                                                                                                               match self.construct_recv_pending_htlc_info(hop_data,
+                                                                                                                       incoming_shared_secret, payment_hash, outgoing_amt_msat,
+                                                                                                                       outgoing_cltv_value, Some(phantom_shared_secret), false, None)
+                                                                                                               {
                                                                                                                        Ok(info) => phantom_receives.push((prev_short_channel_id, prev_funding_outpoint, prev_user_channel_id, vec![(info, prev_htlc_id)])),
                                                                                                                        Err(ReceiveError { err_code, err_data, msg }) => failed_payment!(msg, err_code, err_data, Some(phantom_shared_secret))
                                                                                                                }
@@ -3567,7 +3768,7 @@ where
                                                                                prev_short_channel_id, prev_htlc_id, prev_funding_outpoint, prev_user_channel_id: _,
                                                                                forward_info: PendingHTLCInfo {
                                                                                        incoming_shared_secret, payment_hash, outgoing_amt_msat, outgoing_cltv_value,
-                                                                                       routing: PendingHTLCRouting::Forward { onion_packet, .. }, incoming_amt_msat: _,
+                                                                                       routing: PendingHTLCRouting::Forward { onion_packet, .. }, skimmed_fee_msat, ..
                                                                                },
                                                                        }) => {
                                                                                log_trace!(self.logger, "Adding HTLC from short id {} with payment_hash {} to channel with short id {} after delay", prev_short_channel_id, log_bytes!(payment_hash.0), short_chan_id);
@@ -3581,7 +3782,7 @@ where
                                                                                });
                                                                                if let Err(e) = chan.get_mut().queue_add_htlc(outgoing_amt_msat,
                                                                                        payment_hash, outgoing_cltv_value, htlc_source.clone(),
-                                                                                       onion_packet, &self.logger)
+                                                                                       onion_packet, skimmed_fee_msat, &self.logger)
                                                                                {
                                                                                        if let ChannelError::Ignore(msg) = e {
                                                                                                log_trace!(self.logger, "Failed to forward HTLC with payment_hash {}: {}", log_bytes!(payment_hash.0), msg);
@@ -3625,7 +3826,8 @@ where
                                                        HTLCForwardInfo::AddHTLC(PendingAddHTLCInfo {
                                                                prev_short_channel_id, prev_htlc_id, prev_funding_outpoint, prev_user_channel_id,
                                                                forward_info: PendingHTLCInfo {
-                                                                       routing, incoming_shared_secret, payment_hash, incoming_amt_msat, outgoing_amt_msat, ..
+                                                                       routing, incoming_shared_secret, payment_hash, incoming_amt_msat, outgoing_amt_msat,
+                                                                       skimmed_fee_msat, ..
                                                                }
                                                        }) => {
                                                                let (cltv_expiry, onion_payload, payment_data, phantom_shared_secret, mut onion_fields) = match routing {
@@ -3666,6 +3868,7 @@ where
                                                                        total_msat: if let Some(data) = &payment_data { data.total_msat } else { outgoing_amt_msat },
                                                                        cltv_expiry,
                                                                        onion_payload,
+                                                                       counterparty_skimmed_fee_msat: skimmed_fee_msat,
                                                                };
 
                                                                let mut committed_to_claimable = false;
@@ -3762,11 +3965,16 @@ where
                                                                                        htlcs.push(claimable_htlc);
                                                                                        let amount_msat = htlcs.iter().map(|htlc| htlc.value).sum();
                                                                                        htlcs.iter_mut().for_each(|htlc| htlc.total_value_received = Some(amount_msat));
+                                                                                       let counterparty_skimmed_fee_msat = htlcs.iter()
+                                                                                               .map(|htlc| htlc.counterparty_skimmed_fee_msat.unwrap_or(0)).sum();
+                                                                                       debug_assert!(total_value.saturating_sub(amount_msat) <=
+                                                                                               counterparty_skimmed_fee_msat);
                                                                                        new_events.push_back((events::Event::PaymentClaimable {
                                                                                                receiver_node_id: Some(receiver_node_id),
                                                                                                payment_hash,
                                                                                                purpose: $purpose,
                                                                                                amount_msat,
+                                                                                               counterparty_skimmed_fee_msat,
                                                                                                via_channel_id: Some(prev_channel_id),
                                                                                                via_user_channel_id: Some(prev_user_channel_id),
                                                                                                claim_deadline: Some(earliest_expiry - HTLC_FAIL_BACK_BUFFER),
@@ -3906,8 +4114,7 @@ where
                                        let _ = self.chain_monitor.update_channel(funding_txo, &update);
                                },
                                BackgroundEvent::MonitorUpdateRegeneratedOnStartup { counterparty_node_id, funding_txo, update } => {
-                                       let update_res = self.chain_monitor.update_channel(funding_txo, &update);
-
+                                       let mut updated_chan = false;
                                        let res = {
                                                let per_peer_state = self.per_peer_state.read().unwrap();
                                                if let Some(peer_state_mutex) = per_peer_state.get(&counterparty_node_id) {
@@ -3915,12 +4122,18 @@ where
                                                        let peer_state = &mut *peer_state_lock;
                                                        match peer_state.channel_by_id.entry(funding_txo.to_channel_id()) {
                                                                hash_map::Entry::Occupied(mut chan) => {
-                                                                       handle_new_monitor_update!(self, update_res, update.update_id, peer_state_lock, peer_state, per_peer_state, chan)
+                                                                       updated_chan = true;
+                                                                       handle_new_monitor_update!(self, funding_txo, update.clone(),
+                                                                               peer_state_lock, peer_state, per_peer_state, chan).map(|_| ())
                                                                },
                                                                hash_map::Entry::Vacant(_) => Ok(()),
                                                        }
                                                } else { Ok(()) }
                                        };
+                                       if !updated_chan {
+                                               // TODO: Track this as in-flight even though the channel is closed.
+                                               let _ = self.chain_monitor.update_channel(funding_txo, &update);
+                                       }
                                        // TODO: If this channel has since closed, we're likely providing a payment
                                        // preimage update, which we must ensure is durable! We currently don't,
                                        // however, ensure that.
@@ -3945,18 +4158,18 @@ where
        fn update_channel_fee(&self, chan_id: &[u8; 32], chan: &mut Channel<<SP::Target as SignerProvider>::Signer>, new_feerate: u32) -> NotifyOption {
                if !chan.context.is_outbound() { return NotifyOption::SkipPersist; }
                // If the feerate has decreased by less than half, don't bother
-               if new_feerate <= chan.get_feerate_sat_per_1000_weight() && new_feerate * 2 > chan.get_feerate_sat_per_1000_weight() {
+               if new_feerate <= chan.context.get_feerate_sat_per_1000_weight() && new_feerate * 2 > chan.context.get_feerate_sat_per_1000_weight() {
                        log_trace!(self.logger, "Channel {} does not qualify for a feerate change from {} to {}.",
-                               log_bytes!(chan_id[..]), chan.get_feerate_sat_per_1000_weight(), new_feerate);
+                               log_bytes!(chan_id[..]), chan.context.get_feerate_sat_per_1000_weight(), new_feerate);
                        return NotifyOption::SkipPersist;
                }
                if !chan.context.is_live() {
                        log_trace!(self.logger, "Channel {} does not qualify for a feerate change from {} to {} as it cannot currently be updated (probably the peer is disconnected).",
-                               log_bytes!(chan_id[..]), chan.get_feerate_sat_per_1000_weight(), new_feerate);
+                               log_bytes!(chan_id[..]), chan.context.get_feerate_sat_per_1000_weight(), new_feerate);
                        return NotifyOption::SkipPersist;
                }
                log_trace!(self.logger, "Channel {} qualifies for a feerate change from {} to {}.",
-                       log_bytes!(chan_id[..]), chan.get_feerate_sat_per_1000_weight(), new_feerate);
+                       log_bytes!(chan_id[..]), chan.context.get_feerate_sat_per_1000_weight(), new_feerate);
 
                chan.queue_update_fee(new_feerate, &self.logger);
                NotifyOption::DoPersist
@@ -4501,9 +4714,7 @@ where
                                                                log_bytes!(chan_id), action);
                                                        peer_state.monitor_update_blocked_actions.entry(chan_id).or_insert(Vec::new()).push(action);
                                                }
-                                               let update_id = monitor_update.update_id;
-                                               let update_res = self.chain_monitor.update_channel(prev_hop.outpoint, monitor_update);
-                                               let res = handle_new_monitor_update!(self, update_res, update_id, peer_state_lock,
+                                               let res = handle_new_monitor_update!(self, prev_hop.outpoint, monitor_update, peer_state_lock,
                                                        peer_state, per_peer_state, chan);
                                                if let Err(e) = res {
                                                        // TODO: This is a *critical* error - we probably updated the outbound edge
@@ -4711,12 +4922,18 @@ where
                                hash_map::Entry::Vacant(_) => return,
                        }
                };
-               log_trace!(self.logger, "ChannelMonitor updated to {}. Current highest is {}",
-                       highest_applied_update_id, channel.get().context.get_latest_monitor_update_id());
+               let remaining_in_flight =
+                       if let Some(pending) = peer_state.in_flight_monitor_updates.get_mut(funding_txo) {
+                               pending.retain(|upd| upd.update_id > highest_applied_update_id);
+                               pending.len()
+                       } else { 0 };
+               log_trace!(self.logger, "ChannelMonitor updated to {}. Current highest is {}. {} pending in-flight updates.",
+                       highest_applied_update_id, channel.get().context.get_latest_monitor_update_id(),
+                       remaining_in_flight);
                if !channel.get().is_awaiting_monitor_update() || channel.get().context.get_latest_monitor_update_id() != highest_applied_update_id {
                        return;
                }
-               handle_monitor_update_completion!(self, highest_applied_update_id, peer_state_lock, peer_state, per_peer_state, channel.get_mut());
+               handle_monitor_update_completion!(self, peer_state_lock, peer_state, per_peer_state, channel.get_mut());
        }
 
        /// Accepts a request to open a channel after a [`Event::OpenChannelRequest`].
@@ -4764,16 +4981,17 @@ where
        fn do_accept_inbound_channel(&self, temporary_channel_id: &[u8; 32], counterparty_node_id: &PublicKey, accept_0conf: bool, user_channel_id: u128) -> Result<(), APIError> {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
 
-               let peers_without_funded_channels = self.peers_without_funded_channels(|peer| !peer.channel_by_id.is_empty());
+               let peers_without_funded_channels =
+                       self.peers_without_funded_channels(|peer| { peer.total_channel_count() > 0 });
                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) })?;
                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
-               let is_only_peer_channel = peer_state.channel_by_id.len() == 1;
-               match peer_state.channel_by_id.entry(temporary_channel_id.clone()) {
+               let is_only_peer_channel = peer_state.total_channel_count() == 1;
+               match peer_state.inbound_v1_channel_by_id.entry(temporary_channel_id.clone()) {
                        hash_map::Entry::Occupied(mut channel) => {
-                               if !channel.get().inbound_is_awaiting_accept() {
+                               if !channel.get().is_awaiting_accept() {
                                        return Err(APIError::APIMisuseError { err: "The channel isn't currently awaiting to be accepted.".to_owned() });
                                }
                                if accept_0conf {
@@ -4832,7 +5050,7 @@ where
                                let peer = peer_mtx.lock().unwrap();
                                if !maybe_count_peer(&*peer) { continue; }
                                let num_unfunded_channels = Self::unfunded_channel_count(&peer, best_block_height);
-                               if num_unfunded_channels == peer.channel_by_id.len() {
+                               if num_unfunded_channels == peer.total_channel_count() {
                                        peers_without_funded_channels += 1;
                                }
                        }
@@ -4845,12 +5063,19 @@ where
        ) -> usize {
                let mut num_unfunded_channels = 0;
                for (_, chan) in peer.channel_by_id.iter() {
+                       // This covers non-zero-conf inbound `Channel`s that we are currently monitoring, but those
+                       // which have not yet had any confirmations on-chain.
                        if !chan.context.is_outbound() && chan.context.minimum_depth().unwrap_or(1) != 0 &&
                                chan.context.get_funding_tx_confirmations(best_block_height) == 0
                        {
                                num_unfunded_channels += 1;
                        }
                }
+               for (_, chan) in peer.inbound_v1_channel_by_id.iter() {
+                       if chan.context.minimum_depth().unwrap_or(1) != 0 {
+                               num_unfunded_channels += 1;
+                       }
+               }
                num_unfunded_channels
        }
 
@@ -4871,7 +5096,8 @@ where
                // Get the number of peers with channels, but without funded ones. We don't care too much
                // about peers that never open a channel, so we filter by peers that have at least one
                // channel, and then limit the number of those with unfunded channels.
-               let channeled_peers_without_funding = self.peers_without_funded_channels(|node| !node.channel_by_id.is_empty());
+               let channeled_peers_without_funding =
+                       self.peers_without_funded_channels(|node| node.total_channel_count() > 0);
 
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex = per_peer_state.get(counterparty_node_id)
@@ -4885,7 +5111,7 @@ where
                // If this peer already has some channels, a new channel won't increase our number of peers
                // with unfunded channels, so as long as we aren't over the maximum number of unfunded
                // channels per-peer we can accept channels from a peer with existing ones.
-               if peer_state.channel_by_id.is_empty() &&
+               if peer_state.total_channel_count() == 0 &&
                        channeled_peers_without_funding >= MAX_UNFUNDED_CHANNEL_PEERS &&
                        !self.default_configuration.manually_accept_inbound_channels
                {
@@ -4901,7 +5127,7 @@ where
                                msg.temporary_channel_id.clone()));
                }
 
-               let mut channel = match Channel::new_from_req(&self.fee_estimator, &self.entropy_source, &self.signer_provider,
+               let mut channel = match InboundV1Channel::new(&self.fee_estimator, &self.entropy_source, &self.signer_provider,
                        counterparty_node_id.clone(), &self.channel_type_features(), &peer_state.latest_features, msg, user_channel_id,
                        &self.default_configuration, best_block_height, &self.logger, outbound_scid_alias)
                {
@@ -4911,33 +5137,35 @@ where
                        },
                        Ok(res) => res
                };
-               match peer_state.channel_by_id.entry(channel.context.channel_id()) {
-                       hash_map::Entry::Occupied(_) => {
-                               self.outbound_scid_aliases.lock().unwrap().remove(&outbound_scid_alias);
-                               return Err(MsgHandleErrInternal::send_err_msg_no_close("temporary_channel_id collision for the same peer!".to_owned(), msg.temporary_channel_id.clone()))
-                       },
-                       hash_map::Entry::Vacant(entry) => {
-                               if !self.default_configuration.manually_accept_inbound_channels {
-                                       if channel.context.get_channel_type().requires_zero_conf() {
-                                               return Err(MsgHandleErrInternal::send_err_msg_no_close("No zero confirmation channels accepted".to_owned(), msg.temporary_channel_id.clone()));
-                                       }
-                                       peer_state.pending_msg_events.push(events::MessageSendEvent::SendAcceptChannel {
-                                               node_id: counterparty_node_id.clone(),
-                                               msg: channel.accept_inbound_channel(user_channel_id),
-                                       });
-                               } else {
-                                       let mut pending_events = self.pending_events.lock().unwrap();
-                                       pending_events.push_back((events::Event::OpenChannelRequest {
-                                               temporary_channel_id: msg.temporary_channel_id.clone(),
-                                               counterparty_node_id: counterparty_node_id.clone(),
-                                               funding_satoshis: msg.funding_satoshis,
-                                               push_msat: msg.push_msat,
-                                               channel_type: channel.context.get_channel_type().clone(),
-                                       }, None));
+               let channel_id = channel.context.channel_id();
+               let channel_exists = peer_state.has_channel(&channel_id);
+               if channel_exists {
+                       self.outbound_scid_aliases.lock().unwrap().remove(&outbound_scid_alias);
+                       return Err(MsgHandleErrInternal::send_err_msg_no_close("temporary_channel_id collision for the same peer!".to_owned(), msg.temporary_channel_id.clone()))
+               } else {
+                       if !self.default_configuration.manually_accept_inbound_channels {
+                               let channel_type = channel.context.get_channel_type();
+                               if channel_type.requires_zero_conf() {
+                                       return Err(MsgHandleErrInternal::send_err_msg_no_close("No zero confirmation channels accepted".to_owned(), msg.temporary_channel_id.clone()));
                                }
-
-                               entry.insert(channel);
+                               if channel_type.requires_anchors_zero_fee_htlc_tx() {
+                                       return Err(MsgHandleErrInternal::send_err_msg_no_close("No channels with anchor outputs accepted".to_owned(), msg.temporary_channel_id.clone()));
+                               }
+                               peer_state.pending_msg_events.push(events::MessageSendEvent::SendAcceptChannel {
+                                       node_id: counterparty_node_id.clone(),
+                                       msg: channel.accept_inbound_channel(user_channel_id),
+                               });
+                       } else {
+                               let mut pending_events = self.pending_events.lock().unwrap();
+                               pending_events.push_back((events::Event::OpenChannelRequest {
+                                       temporary_channel_id: msg.temporary_channel_id.clone(),
+                                       counterparty_node_id: counterparty_node_id.clone(),
+                                       funding_satoshis: msg.funding_satoshis,
+                                       push_msat: msg.push_msat,
+                                       channel_type: channel.context.get_channel_type().clone(),
+                               }, None));
                        }
+                       peer_state.inbound_v1_channel_by_id.insert(channel_id, channel);
                }
                Ok(())
        }
@@ -4952,9 +5180,9 @@ where
                                })?;
                        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) {
+                       match peer_state.outbound_v1_channel_by_id.entry(msg.temporary_channel_id) {
                                hash_map::Entry::Occupied(mut chan) => {
-                                       try_chan_entry!(self, chan.get_mut().accept_channel(&msg, &self.default_configuration.channel_handshake_limits, &peer_state.latest_features), chan);
+                                       try_v1_outbound_chan_entry!(self, chan.get_mut().accept_channel(&msg, &self.default_configuration.channel_handshake_limits, &peer_state.latest_features), chan);
                                        (chan.get().context.get_value_satoshis(), chan.get().context.get_funding_redeemscript().to_v0_p2wsh(), chan.get().context.get_user_id())
                                },
                                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.temporary_channel_id))
@@ -4983,12 +5211,24 @@ where
 
                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
-               let ((funding_msg, monitor), chan) =
-                       match peer_state.channel_by_id.entry(msg.temporary_channel_id) {
-                               hash_map::Entry::Occupied(mut chan) => {
-                                       (try_chan_entry!(self, chan.get_mut().funding_created(msg, best_block, &self.signer_provider, &self.logger), chan), chan.remove())
+               let (chan, funding_msg, monitor) =
+                       match peer_state.inbound_v1_channel_by_id.remove(&msg.temporary_channel_id) {
+                               Some(inbound_chan) => {
+                                       match inbound_chan.funding_created(msg, best_block, &self.signer_provider, &self.logger) {
+                                               Ok(res) => res,
+                                               Err((mut inbound_chan, err)) => {
+                                                       // We've already removed this inbound channel from the map in `PeerState`
+                                                       // above so at this point we just need to clean up any lingering entries
+                                                       // concerning this channel as it is safe to do so.
+                                                       update_maps_on_chan_removal!(self, &inbound_chan.context);
+                                                       let user_id = inbound_chan.context.get_user_id();
+                                                       let shutdown_res = inbound_chan.context.force_shutdown(false);
+                                                       return Err(MsgHandleErrInternal::from_finish_shutdown(format!("{}", err),
+                                                               msg.temporary_channel_id, user_id, shutdown_res, None));
+                                               },
+                                       }
                                },
-                               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.temporary_channel_id))
+                               None => 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.temporary_channel_id))
                        };
 
                match peer_state.channel_by_id.entry(funding_msg.channel_id) {
@@ -5020,8 +5260,9 @@ where
                                let monitor_res = self.chain_monitor.watch_channel(monitor.get_funding_txo().0, monitor);
 
                                let chan = e.insert(chan);
-                               let mut res = handle_new_monitor_update!(self, monitor_res, 0, peer_state_lock, peer_state,
-                                       per_peer_state, chan, MANUALLY_REMOVING, { peer_state.channel_by_id.remove(&new_channel_id) });
+                               let mut res = handle_new_monitor_update!(self, monitor_res, peer_state_lock, peer_state,
+                                       per_peer_state, chan, MANUALLY_REMOVING_INITIAL_MONITOR,
+                                       { peer_state.channel_by_id.remove(&new_channel_id) });
 
                                // Note that we reply with the new channel_id in error messages if we gave up on the
                                // channel, not the temporary_channel_id. This is compatible with ourselves, but the
@@ -5033,7 +5274,7 @@ where
                                if let Err(MsgHandleErrInternal { shutdown_finish: Some((res, _)), .. }) = &mut res {
                                        res.0 = None;
                                }
-                               res
+                               res.map(|_| ())
                        }
                }
        }
@@ -5054,7 +5295,7 @@ where
                                let monitor = try_chan_entry!(self,
                                        chan.get_mut().funding_signed(&msg, best_block, &self.signer_provider, &self.logger), chan);
                                let update_res = self.chain_monitor.watch_channel(chan.get().context.get_funding_txo().unwrap(), monitor);
-                               let mut res = handle_new_monitor_update!(self, update_res, 0, peer_state_lock, peer_state, per_peer_state, chan);
+                               let mut res = handle_new_monitor_update!(self, update_res, peer_state_lock, peer_state, per_peer_state, chan, INITIAL_MONITOR);
                                if let Err(MsgHandleErrInternal { ref mut shutdown_finish, .. }) = res {
                                        // We weren't able to watch the channel to begin with, so no updates should be made on
                                        // it. Previously, full_stack_target found an (unreachable) panic when the
@@ -5063,7 +5304,7 @@ where
                                                shutdown_finish.0.take();
                                        }
                                }
-                               res
+                               res.map(|_| ())
                        },
                        hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close("Failed to find corresponding channel".to_owned(), msg.channel_id))
                }
@@ -5151,9 +5392,8 @@ where
 
                                        // Update the monitor with the shutdown script if necessary.
                                        if let Some(monitor_update) = monitor_update_opt {
-                                               let update_id = monitor_update.update_id;
-                                               let update_res = self.chain_monitor.update_channel(funding_txo_opt.unwrap(), monitor_update);
-                                               break handle_new_monitor_update!(self, update_res, update_id, peer_state_lock, peer_state, per_peer_state, chan_entry);
+                                               break handle_new_monitor_update!(self, funding_txo_opt.unwrap(), monitor_update,
+                                                       peer_state_lock, peer_state, per_peer_state, chan_entry).map(|_| ());
                                        }
                                        break Ok(());
                                },
@@ -5212,7 +5452,7 @@ where
                                        msg: update
                                });
                        }
-                       self.issue_channel_close_events(&chan, ClosureReason::CooperativeClosure);
+                       self.issue_channel_close_events(&chan.context, ClosureReason::CooperativeClosure);
                }
                Ok(())
        }
@@ -5227,7 +5467,7 @@ where
                //encrypted with the same key. It's not immediately obvious how to usefully exploit that,
                //but we should prevent it anyway.
 
-               let pending_forward_info = self.decode_update_add_htlc_onion(msg);
+               let decoded_hop_res = 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(|| {
@@ -5239,6 +5479,12 @@ where
                match peer_state.channel_by_id.entry(msg.channel_id) {
                        hash_map::Entry::Occupied(mut chan) => {
 
+                               let pending_forward_info = match decoded_hop_res {
+                                       Ok((next_hop, shared_secret, next_packet_pk_opt)) =>
+                                               self.construct_pending_htlc_status(msg, shared_secret, next_hop,
+                                                       chan.get().context.config().accept_underpaying_htlcs, next_packet_pk_opt),
+                                       Err(e) => PendingHTLCStatus::Fail(e)
+                               };
                                let create_pending_htlc_status = |chan: &Channel<<SP::Target as SignerProvider>::Signer>, pending_forward_info: PendingHTLCStatus, error_code: u16| {
                                        // If the update_add is completely bogus, the call will Err and we will close,
                                        // but if we've sent a shutdown and they haven't acknowledged it yet, we just
@@ -5343,10 +5589,8 @@ where
                                let funding_txo = chan.get().context.get_funding_txo();
                                let monitor_update_opt = try_chan_entry!(self, chan.get_mut().commitment_signed(&msg, &self.logger), chan);
                                if let Some(monitor_update) = monitor_update_opt {
-                                       let update_res = self.chain_monitor.update_channel(funding_txo.unwrap(), monitor_update);
-                                       let update_id = monitor_update.update_id;
-                                       handle_new_monitor_update!(self, update_res, update_id, peer_state_lock,
-                                               peer_state, per_peer_state, chan)
+                                       handle_new_monitor_update!(self, funding_txo.unwrap(), monitor_update, peer_state_lock,
+                                               peer_state, per_peer_state, chan).map(|_| ())
                                } else { Ok(()) }
                        },
                        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))
@@ -5482,10 +5726,8 @@ where
                                        let funding_txo = chan.get().context.get_funding_txo();
                                        let (htlcs_to_fail, monitor_update_opt) = try_chan_entry!(self, chan.get_mut().revoke_and_ack(&msg, &self.logger), chan);
                                        let res = if let Some(monitor_update) = monitor_update_opt {
-                                               let update_res = self.chain_monitor.update_channel(funding_txo.unwrap(), monitor_update);
-                                               let update_id = monitor_update.update_id;
-                                               handle_new_monitor_update!(self, update_res, update_id,
-                                                       peer_state_lock, peer_state, per_peer_state, chan)
+                                               handle_new_monitor_update!(self, funding_txo.unwrap(), monitor_update,
+                                                       peer_state_lock, peer_state, per_peer_state, chan).map(|_| ())
                                        } else { Ok(()) };
                                        (htlcs_to_fail, res)
                                },
@@ -5686,7 +5928,7 @@ where
                                                                let pending_msg_events = &mut peer_state.pending_msg_events;
                                                                if let hash_map::Entry::Occupied(chan_entry) = peer_state.channel_by_id.entry(funding_outpoint.to_channel_id()) {
                                                                        let mut chan = remove_channel!(self, chan_entry);
-                                                                       failed_channels.push(chan.force_shutdown(false));
+                                                                       failed_channels.push(chan.context.force_shutdown(false));
                                                                        if let Ok(update) = self.get_channel_update_for_broadcast(&chan) {
                                                                                pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
                                                                                        msg: update
@@ -5697,7 +5939,7 @@ where
                                                                        } else {
                                                                                ClosureReason::CommitmentTxConfirmed
                                                                        };
-                                                                       self.issue_channel_close_events(&chan, reason);
+                                                                       self.issue_channel_close_events(&chan.context, reason);
                                                                        pending_msg_events.push(events::MessageSendEvent::HandleError {
                                                                                node_id: chan.context.get_counterparty_node_id(),
                                                                                action: msgs::ErrorAction::SendErrorMessage {
@@ -5760,11 +6002,8 @@ where
                                                if let Some(monitor_update) = monitor_opt {
                                                        has_monitor_update = true;
 
-                                                       let update_res = self.chain_monitor.update_channel(
-                                                               funding_txo.expect("channel is live"), monitor_update);
-                                                       let update_id = monitor_update.update_id;
                                                        let channel_id: [u8; 32] = *channel_id;
-                                                       let res = handle_new_monitor_update!(self, update_res, update_id,
+                                                       let res = handle_new_monitor_update!(self, funding_txo.unwrap(), monitor_update,
                                                                peer_state_lock, peer_state, per_peer_state, chan, MANUALLY_REMOVING,
                                                                peer_state.channel_by_id.remove(&channel_id));
                                                        if res.is_err() {
@@ -5822,11 +6061,11 @@ where
                                                                        });
                                                                }
 
-                                                               self.issue_channel_close_events(chan, ClosureReason::CooperativeClosure);
+                                                               self.issue_channel_close_events(&chan.context, ClosureReason::CooperativeClosure);
 
                                                                log_info!(self.logger, "Broadcasting {}", log_tx!(tx));
                                                                self.tx_broadcaster.broadcast_transactions(&[&tx]);
-                                                               update_maps_on_chan_removal!(self, chan);
+                                                               update_maps_on_chan_removal!(self, &chan.context);
                                                                false
                                                        } else { true }
                                                },
@@ -5874,37 +6113,6 @@ where
                }
        }
 
-       fn set_payment_hash_secret_map(&self, payment_hash: PaymentHash, payment_preimage: Option<PaymentPreimage>, min_value_msat: Option<u64>, invoice_expiry_delta_secs: u32) -> Result<PaymentSecret, APIError> {
-               assert!(invoice_expiry_delta_secs <= 60*60*24*365); // Sadly bitcoin timestamps are u32s, so panic before 2106
-
-               if min_value_msat.is_some() && min_value_msat.unwrap() > MAX_VALUE_MSAT {
-                       return Err(APIError::APIMisuseError { err: format!("min_value_msat of {} greater than total 21 million bitcoin supply", min_value_msat.unwrap()) });
-               }
-
-               let payment_secret = PaymentSecret(self.entropy_source.get_secure_random_bytes());
-
-               let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
-               let mut payment_secrets = self.pending_inbound_payments.lock().unwrap();
-               match payment_secrets.entry(payment_hash) {
-                       hash_map::Entry::Vacant(e) => {
-                               e.insert(PendingInboundPayment {
-                                       payment_secret, min_value_msat, payment_preimage,
-                                       user_payment_id: 0, // For compatibility with version 0.0.103 and earlier
-                                       // We assume that highest_seen_timestamp is pretty close to the current time -
-                                       // it's updated when we receive a new block with the maximum time we've seen in
-                                       // a header. It should never be more than two hours in the future.
-                                       // Thus, we add two hours here as a buffer to ensure we absolutely
-                                       // never fail a payment too early.
-                                       // Note that we assume that received blocks have reasonably up-to-date
-                                       // timestamps.
-                                       expiry_time: self.highest_seen_timestamp.load(Ordering::Acquire) as u64 + invoice_expiry_delta_secs as u64 + 7200,
-                               });
-                       },
-                       hash_map::Entry::Occupied(_) => return Err(APIError::APIMisuseError { err: "Duplicate payment hash".to_owned() }),
-               }
-               Ok(payment_secret)
-       }
-
        /// Gets a payment secret and payment hash for use in an invoice given to a third party wishing
        /// to pay us.
        ///
@@ -5944,23 +6152,6 @@ where
                        min_final_cltv_expiry_delta)
        }
 
-       /// Legacy version of [`create_inbound_payment`]. Use this method if you wish to share
-       /// serialized state with LDK node(s) running 0.0.103 and earlier.
-       ///
-       /// May panic if `invoice_expiry_delta_secs` is greater than one year.
-       ///
-       /// # Note
-       /// This method is deprecated and will be removed soon.
-       ///
-       /// [`create_inbound_payment`]: Self::create_inbound_payment
-       #[deprecated]
-       pub fn create_inbound_payment_legacy(&self, min_value_msat: Option<u64>, invoice_expiry_delta_secs: u32) -> Result<(PaymentHash, PaymentSecret), APIError> {
-               let payment_preimage = PaymentPreimage(self.entropy_source.get_secure_random_bytes());
-               let payment_hash = PaymentHash(Sha256::hash(&payment_preimage.0).into_inner());
-               let payment_secret = self.set_payment_hash_secret_map(payment_hash, Some(payment_preimage), min_value_msat, invoice_expiry_delta_secs)?;
-               Ok((payment_hash, payment_secret))
-       }
-
        /// Gets a [`PaymentSecret`] for a given [`PaymentHash`], for which the payment preimage is
        /// stored external to LDK.
        ///
@@ -6014,20 +6205,6 @@ where
                        min_final_cltv_expiry)
        }
 
-       /// Legacy version of [`create_inbound_payment_for_hash`]. Use this method if you wish to share
-       /// serialized state with LDK node(s) running 0.0.103 and earlier.
-       ///
-       /// May panic if `invoice_expiry_delta_secs` is greater than one year.
-       ///
-       /// # Note
-       /// This method is deprecated and will be removed soon.
-       ///
-       /// [`create_inbound_payment_for_hash`]: Self::create_inbound_payment_for_hash
-       #[deprecated]
-       pub fn create_inbound_payment_for_hash_legacy(&self, payment_hash: PaymentHash, min_value_msat: Option<u64>, invoice_expiry_delta_secs: u32) -> Result<PaymentSecret, APIError> {
-               self.set_payment_hash_secret_map(payment_hash, None, min_value_msat, invoice_expiry_delta_secs)
-       }
-
        /// Gets an LDK-generated payment preimage from a payment hash and payment secret that were
        /// previously returned from [`create_inbound_payment`].
        ///
@@ -6102,7 +6279,7 @@ where
                inflight_htlcs
        }
 
-       #[cfg(any(test, fuzzing, feature = "_test_utils"))]
+       #[cfg(any(test, feature = "_test_utils"))]
        pub fn get_and_clear_pending_events(&self) -> Vec<events::Event> {
                let events = core::cell::RefCell::new(Vec::new());
                let event_handler = |event: events::Event| events.borrow_mut().push(event);
@@ -6168,9 +6345,7 @@ where
                                        if let Some((monitor_update, further_update_exists)) = chan.get_mut().unblock_next_blocked_monitor_update() {
                                                log_debug!(self.logger, "Unlocking monitor updating for channel {} and updating monitor",
                                                        log_bytes!(&channel_funding_outpoint.to_channel_id()[..]));
-                                               let update_res = self.chain_monitor.update_channel(channel_funding_outpoint, monitor_update);
-                                               let update_id = monitor_update.update_id;
-                                               if let Err(e) = handle_new_monitor_update!(self, update_res, update_id,
+                                               if let Err(e) = handle_new_monitor_update!(self, channel_funding_outpoint, monitor_update,
                                                        peer_state_lck, peer_state, per_peer_state, chan)
                                                {
                                                        errors.push((e, counterparty_node_id));
@@ -6530,17 +6705,17 @@ where
                                                        }
                                                }
                                        } else if let Err(reason) = res {
-                                               update_maps_on_chan_removal!(self, channel);
+                                               update_maps_on_chan_removal!(self, &channel.context);
                                                // It looks like our counterparty went on-chain or funding transaction was
                                                // reorged out of the main chain. Close the channel.
-                                               failed_channels.push(channel.force_shutdown(true));
+                                               failed_channels.push(channel.context.force_shutdown(true));
                                                if let Ok(update) = self.get_channel_update_for_broadcast(&channel) {
                                                        pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
                                                                msg: update
                                                        });
                                                }
                                                let reason_message = format!("{}", reason);
-                                               self.issue_channel_close_events(channel, reason);
+                                               self.issue_channel_close_events(&channel.context, reason);
                                                pending_msg_events.push(events::MessageSendEvent::HandleError {
                                                        node_id: channel.context.get_counterparty_node_id(),
                                                        action: msgs::ErrorAction::SendErrorMessage { msg: msgs::ErrorMessage {
@@ -6790,12 +6965,22 @@ where
                                peer_state.channel_by_id.retain(|_, chan| {
                                        chan.remove_uncommitted_htlcs_and_mark_paused(&self.logger);
                                        if chan.is_shutdown() {
-                                               update_maps_on_chan_removal!(self, chan);
-                                               self.issue_channel_close_events(chan, ClosureReason::DisconnectedPeer);
+                                               update_maps_on_chan_removal!(self, &chan.context);
+                                               self.issue_channel_close_events(&chan.context, ClosureReason::DisconnectedPeer);
                                                return false;
                                        }
                                        true
                                });
+                               peer_state.inbound_v1_channel_by_id.retain(|_, chan| {
+                                       update_maps_on_chan_removal!(self, &chan.context);
+                                       self.issue_channel_close_events(&chan.context, ClosureReason::DisconnectedPeer);
+                                       false
+                               });
+                               peer_state.outbound_v1_channel_by_id.retain(|_, chan| {
+                                       update_maps_on_chan_removal!(self, &chan.context);
+                                       self.issue_channel_close_events(&chan.context, ClosureReason::DisconnectedPeer);
+                                       false
+                               });
                                pending_msg_events.retain(|msg| {
                                        match msg {
                                                // V1 Channel Establishment
@@ -6877,8 +7062,11 @@ where
                                        }
                                        e.insert(Mutex::new(PeerState {
                                                channel_by_id: HashMap::new(),
+                                               outbound_v1_channel_by_id: HashMap::new(),
+                                               inbound_v1_channel_by_id: HashMap::new(),
                                                latest_features: init_msg.features.clone(),
                                                pending_msg_events: Vec::new(),
+                                               in_flight_monitor_updates: BTreeMap::new(),
                                                monitor_update_blocked_actions: BTreeMap::new(),
                                                actions_blocking_raa_monitor_updates: BTreeMap::new(),
                                                is_connected: true,
@@ -6952,7 +7140,9 @@ where
                                if peer_state_mutex_opt.is_none() { return; }
                                let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
                                let peer_state = &mut *peer_state_lock;
-                               peer_state.channel_by_id.keys().cloned().collect()
+                               peer_state.channel_by_id.keys().cloned()
+                                       .chain(peer_state.outbound_v1_channel_by_id.keys().cloned())
+                                       .chain(peer_state.inbound_v1_channel_by_id.keys().cloned()).collect()
                        };
                        for channel_id in channel_ids {
                                // Untrusted messages from peer, we throw away the error if id points to a non-existent channel
@@ -6966,7 +7156,7 @@ where
                                if peer_state_mutex_opt.is_none() { return; }
                                let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
                                let peer_state = &mut *peer_state_lock;
-                               if let Some(chan) = peer_state.channel_by_id.get_mut(&msg.channel_id) {
+                               if let Some(chan) = peer_state.outbound_v1_channel_by_id.get_mut(&msg.channel_id) {
                                        if let Ok(msg) = chan.maybe_handle_error_without_close(self.genesis_hash) {
                                                peer_state.pending_msg_events.push(events::MessageSendEvent::SendOpenChannel {
                                                        node_id: *counterparty_node_id,
@@ -7079,7 +7269,7 @@ pub(crate) fn provided_channel_type_features(config: &UserConfig) -> ChannelType
 
 /// Fetches the set of [`InitFeatures`] flags which are provided by or required by
 /// [`ChannelManager`].
-pub fn provided_init_features(_config: &UserConfig) -> InitFeatures {
+pub fn provided_init_features(config: &UserConfig) -> InitFeatures {
        // Note that if new features are added here which other peers may (eventually) require, we
        // should also add the corresponding (optional) bit to the [`ChannelMessageHandler`] impl for
        // [`ErroringMessageHandler`].
@@ -7095,11 +7285,8 @@ pub fn provided_init_features(_config: &UserConfig) -> InitFeatures {
        features.set_channel_type_optional();
        features.set_scid_privacy_optional();
        features.set_zero_conf_optional();
-       #[cfg(anchors)]
-       { // Attributes are not allowed on if expressions on our current MSRV of 1.41.
-               if _config.channel_handshake_config.negotiate_anchors_zero_fee_htlc_tx {
-                       features.set_anchors_zero_fee_htlc_tx_optional();
-               }
+       if config.channel_handshake_config.negotiate_anchors_zero_fee_htlc_tx {
+               features.set_anchors_zero_fee_htlc_tx_optional();
        }
        features
 }
@@ -7264,6 +7451,7 @@ impl_writeable_tlv_based!(PendingHTLCInfo, {
        (6, outgoing_amt_msat, required),
        (8, outgoing_cltv_value, required),
        (9, incoming_amt_msat, option),
+       (10, skimmed_fee_msat, option),
 });
 
 
@@ -7362,6 +7550,7 @@ impl Writeable for ClaimableHTLC {
                        (5, self.total_value_received, option),
                        (6, self.cltv_expiry, required),
                        (8, keysend_preimage, option),
+                       (10, self.counterparty_skimmed_fee_msat, option),
                });
                Ok(())
        }
@@ -7369,24 +7558,19 @@ impl Writeable for ClaimableHTLC {
 
 impl Readable for ClaimableHTLC {
        fn read<R: Read>(reader: &mut R) -> Result<Self, DecodeError> {
-               let mut prev_hop = crate::util::ser::RequiredWrapper(None);
-               let mut value = 0;
-               let mut sender_intended_value = None;
-               let mut payment_data: Option<msgs::FinalOnionHopData> = None;
-               let mut cltv_expiry = 0;
-               let mut total_value_received = None;
-               let mut total_msat = None;
-               let mut keysend_preimage: Option<PaymentPreimage> = None;
-               read_tlv_fields!(reader, {
+               _init_and_read_tlv_fields!(reader, {
                        (0, prev_hop, required),
                        (1, total_msat, option),
-                       (2, value, required),
+                       (2, value_ser, required),
                        (3, sender_intended_value, option),
-                       (4, payment_data, option),
+                       (4, payment_data_opt, option),
                        (5, total_value_received, option),
                        (6, cltv_expiry, required),
-                       (8, keysend_preimage, option)
+                       (8, keysend_preimage, option),
+                       (10, counterparty_skimmed_fee_msat, option),
                });
+               let payment_data: Option<msgs::FinalOnionHopData> = payment_data_opt;
+               let value = value_ser.0.unwrap();
                let onion_payload = match keysend_preimage {
                        Some(p) => {
                                if payment_data.is_some() {
@@ -7415,7 +7599,8 @@ impl Readable for ClaimableHTLC {
                        total_value_received,
                        total_msat: total_msat.unwrap(),
                        onion_payload,
-                       cltv_expiry,
+                       cltv_expiry: cltv_expiry.0.unwrap(),
+                       counterparty_skimmed_fee_msat,
                })
        }
 }
@@ -7710,6 +7895,16 @@ where
                        pending_claiming_payments = None;
                }
 
+               let mut in_flight_monitor_updates: Option<HashMap<(&PublicKey, &OutPoint), &Vec<ChannelMonitorUpdate>>> = None;
+               for ((counterparty_id, _), peer_state) in per_peer_state.iter().zip(peer_states.iter()) {
+                       for (funding_outpoint, updates) in peer_state.in_flight_monitor_updates.iter() {
+                               if !updates.is_empty() {
+                                       if in_flight_monitor_updates.is_none() { in_flight_monitor_updates = Some(HashMap::new()); }
+                                       in_flight_monitor_updates.as_mut().unwrap().insert((counterparty_id, funding_outpoint), updates);
+                               }
+                       }
+               }
+
                write_tlv_fields!(writer, {
                        (1, pending_outbound_payments_no_retry, required),
                        (2, pending_intercepted_htlcs, option),
@@ -7720,6 +7915,7 @@ where
                        (7, self.fake_scid_rand_bytes, required),
                        (8, if events_not_backwards_compatible { Some(&*events) } else { None }, option),
                        (9, htlc_purposes, vec_type),
+                       (10, in_flight_monitor_updates, option),
                        (11, self.probing_cookie_secret, required),
                        (13, htlc_onion_fields, optional_vec),
                });
@@ -7936,7 +8132,7 @@ where
                let mut id_to_peer = HashMap::with_capacity(cmp::min(channel_count as usize, 128));
                let mut short_to_chan_info = HashMap::with_capacity(cmp::min(channel_count as usize, 128));
                let mut channel_closures = VecDeque::new();
-               let mut pending_background_events = Vec::new();
+               let mut close_background_events = Vec::new();
                for _ in 0..channel_count {
                        let mut channel: Channel<<SP::Target as SignerProvider>::Signer> = Channel::read(reader, (
                                &args.entropy_source, &args.signer_provider, best_block_height, &provided_channel_type_features(&args.default_config)
@@ -7944,17 +8140,7 @@ where
                        let funding_txo = channel.context.get_funding_txo().ok_or(DecodeError::InvalidValue)?;
                        funding_txo_set.insert(funding_txo.clone());
                        if let Some(ref mut monitor) = args.channel_monitors.get_mut(&funding_txo) {
-                               if channel.get_latest_complete_monitor_update_id() > monitor.get_latest_update_id() {
-                                       // If the channel is ahead of the monitor, return InvalidValue:
-                                       log_error!(args.logger, "A ChannelMonitor is stale compared to the current ChannelManager! This indicates a potentially-critical violation of the chain::Watch API!");
-                                       log_error!(args.logger, " The ChannelMonitor for channel {} is at update_id {} but the ChannelManager is at update_id {}.",
-                                               log_bytes!(channel.context.channel_id()), monitor.get_latest_update_id(), channel.get_latest_complete_monitor_update_id());
-                                       log_error!(args.logger, " The chain::Watch API *requires* that monitors are persisted durably before returning,");
-                                       log_error!(args.logger, " client applications must ensure that ChannelMonitor data is always available and the latest to avoid funds loss!");
-                                       log_error!(args.logger, " Without the latest ChannelMonitor we cannot continue without risking funds.");
-                                       log_error!(args.logger, " Please ensure the chain::Watch API requirements are met and file a bug report at https://github.com/lightningdevkit/rust-lightning");
-                                       return Err(DecodeError::InvalidValue);
-                               } else if channel.get_cur_holder_commitment_transaction_number() > monitor.get_cur_holder_commitment_number() ||
+                               if channel.get_cur_holder_commitment_transaction_number() > monitor.get_cur_holder_commitment_number() ||
                                                channel.get_revoked_counterparty_commitment_transaction_number() > monitor.get_min_seen_secret() ||
                                                channel.get_cur_counterparty_commitment_transaction_number() > monitor.get_cur_counterparty_commitment_number() ||
                                                channel.context.get_latest_monitor_update_id() < monitor.get_latest_update_id() {
@@ -7963,9 +8149,9 @@ where
                                        log_error!(args.logger, " The channel will be force-closed and the latest commitment transaction from the ChannelMonitor broadcast.");
                                        log_error!(args.logger, " The ChannelMonitor for channel {} is at update_id {} but the ChannelManager is at update_id {}.",
                                                log_bytes!(channel.context.channel_id()), monitor.get_latest_update_id(), channel.context.get_latest_monitor_update_id());
-                                       let (monitor_update, mut new_failed_htlcs) = channel.force_shutdown(true);
+                                       let (monitor_update, mut new_failed_htlcs) = channel.context.force_shutdown(true);
                                        if let Some((counterparty_node_id, funding_txo, update)) = monitor_update {
-                                               pending_background_events.push(BackgroundEvent::MonitorUpdateRegeneratedOnStartup {
+                                               close_background_events.push(BackgroundEvent::MonitorUpdateRegeneratedOnStartup {
                                                        counterparty_node_id, funding_txo, update
                                                });
                                        }
@@ -7998,7 +8184,6 @@ where
                                        log_info!(args.logger, "Successfully loaded channel {} at update_id {} against monitor at update id {}",
                                                log_bytes!(channel.context.channel_id()), channel.context.get_latest_monitor_update_id(),
                                                monitor.get_latest_update_id());
-                                       channel.complete_all_mon_updates_through(monitor.get_latest_update_id());
                                        if let Some(short_channel_id) = channel.context.get_short_channel_id() {
                                                short_to_chan_info.insert(short_channel_id, (channel.context.get_counterparty_node_id(), channel.context.channel_id()));
                                        }
@@ -8021,7 +8206,7 @@ where
                                // If we were persisted and shut down while the initial ChannelMonitor persistence
                                // was in-progress, we never broadcasted the funding transaction and can still
                                // safely discard the channel.
-                               let _ = channel.force_shutdown(false);
+                               let _ = channel.context.force_shutdown(false);
                                channel_closures.push_back((events::Event::ChannelClosed {
                                        channel_id: channel.context.channel_id(),
                                        user_channel_id: channel.context.get_user_id(),
@@ -8045,7 +8230,7 @@ where
                                        update_id: CLOSED_CHANNEL_UPDATE_ID,
                                        updates: vec![ChannelMonitorUpdateStep::ChannelForceClosed { should_broadcast: true }],
                                };
-                               pending_background_events.push(BackgroundEvent::ClosingMonitorUpdateRegeneratedOnStartup((*funding_txo, monitor_update)));
+                               close_background_events.push(BackgroundEvent::ClosingMonitorUpdateRegeneratedOnStartup((*funding_txo, monitor_update)));
                        }
                }
 
@@ -8074,18 +8259,27 @@ where
                        claimable_htlcs_list.push((payment_hash, previous_hops));
                }
 
-               let peer_count: u64 = Readable::read(reader)?;
-               let mut per_peer_state = HashMap::with_capacity(cmp::min(peer_count as usize, MAX_ALLOC_SIZE/mem::size_of::<(PublicKey, Mutex<PeerState<<SP::Target as SignerProvider>::Signer>>)>()));
-               for _ in 0..peer_count {
-                       let peer_pubkey = Readable::read(reader)?;
-                       let peer_state = PeerState {
-                               channel_by_id: peer_channels.remove(&peer_pubkey).unwrap_or(HashMap::new()),
-                               latest_features: Readable::read(reader)?,
+               let peer_state_from_chans = |channel_by_id| {
+                       PeerState {
+                               channel_by_id,
+                               outbound_v1_channel_by_id: HashMap::new(),
+                               inbound_v1_channel_by_id: HashMap::new(),
+                               latest_features: InitFeatures::empty(),
                                pending_msg_events: Vec::new(),
+                               in_flight_monitor_updates: BTreeMap::new(),
                                monitor_update_blocked_actions: BTreeMap::new(),
                                actions_blocking_raa_monitor_updates: BTreeMap::new(),
                                is_connected: false,
-                       };
+                       }
+               };
+
+               let peer_count: u64 = Readable::read(reader)?;
+               let mut per_peer_state = HashMap::with_capacity(cmp::min(peer_count as usize, MAX_ALLOC_SIZE/mem::size_of::<(PublicKey, Mutex<PeerState<<SP::Target as SignerProvider>::Signer>>)>()));
+               for _ in 0..peer_count {
+                       let peer_pubkey = Readable::read(reader)?;
+                       let peer_chans = peer_channels.remove(&peer_pubkey).unwrap_or(HashMap::new());
+                       let mut peer_state = peer_state_from_chans(peer_chans);
+                       peer_state.latest_features = Readable::read(reader)?;
                        per_peer_state.insert(peer_pubkey, Mutex::new(peer_state));
                }
 
@@ -8113,24 +8307,6 @@ where
                        }
                }
 
-               for (node_id, peer_mtx) in per_peer_state.iter() {
-                       let peer_state = peer_mtx.lock().unwrap();
-                       for (_, chan) in peer_state.channel_by_id.iter() {
-                               for update in chan.uncompleted_unblocked_mon_updates() {
-                                       if let Some(funding_txo) = chan.context.get_funding_txo() {
-                                               log_trace!(args.logger, "Replaying ChannelMonitorUpdate {} for channel {}",
-                                                       update.update_id, log_bytes!(funding_txo.to_channel_id()));
-                                               pending_background_events.push(
-                                                       BackgroundEvent::MonitorUpdateRegeneratedOnStartup {
-                                                               counterparty_node_id: *node_id, funding_txo, update: update.clone(),
-                                                       });
-                                       } else {
-                                               return Err(DecodeError::InvalidValue);
-                                       }
-                               }
-                       }
-               }
-
                let _last_node_announcement_serial: u32 = Readable::read(reader)?; // Only used < 0.0.111
                let highest_seen_timestamp: u32 = Readable::read(reader)?;
 
@@ -8167,6 +8343,7 @@ where
                let mut pending_claiming_payments = Some(HashMap::new());
                let mut monitor_update_blocked_actions_per_peer: Option<Vec<(_, BTreeMap<_, Vec<_>>)>> = Some(Vec::new());
                let mut events_override = None;
+               let mut in_flight_monitor_updates: Option<HashMap<(PublicKey, OutPoint), Vec<ChannelMonitorUpdate>>> = None;
                read_tlv_fields!(reader, {
                        (1, pending_outbound_payments_no_retry, option),
                        (2, pending_intercepted_htlcs, option),
@@ -8177,6 +8354,7 @@ where
                        (7, fake_scid_rand_bytes, option),
                        (8, events_override, option),
                        (9, claimable_htlc_purposes, vec_type),
+                       (10, in_flight_monitor_updates, option),
                        (11, probing_cookie_secret, option),
                        (13, claimable_htlc_onion_fields, optional_vec),
                });
@@ -8210,6 +8388,103 @@ where
                        retry_lock: Mutex::new(())
                };
 
+               // We have to replay (or skip, if they were completed after we wrote the `ChannelManager`)
+               // each `ChannelMonitorUpdate` in `in_flight_monitor_updates`. After doing so, we have to
+               // check that each channel we have isn't newer than the latest `ChannelMonitorUpdate`(s) we
+               // replayed, and for each monitor update we have to replay we have to ensure there's a
+               // `ChannelMonitor` for it.
+               //
+               // In order to do so we first walk all of our live channels (so that we can check their
+               // state immediately after doing the update replays, when we have the `update_id`s
+               // available) and then walk any remaining in-flight updates.
+               //
+               // Because the actual handling of the in-flight updates is the same, it's macro'ized here:
+               let mut pending_background_events = Vec::new();
+               macro_rules! handle_in_flight_updates {
+                       ($counterparty_node_id: expr, $chan_in_flight_upds: expr, $funding_txo: expr,
+                        $monitor: expr, $peer_state: expr, $channel_info_log: expr
+                       ) => { {
+                               let mut max_in_flight_update_id = 0;
+                               $chan_in_flight_upds.retain(|upd| upd.update_id > $monitor.get_latest_update_id());
+                               for update in $chan_in_flight_upds.iter() {
+                                       log_trace!(args.logger, "Replaying ChannelMonitorUpdate {} for {}channel {}",
+                                               update.update_id, $channel_info_log, log_bytes!($funding_txo.to_channel_id()));
+                                       max_in_flight_update_id = cmp::max(max_in_flight_update_id, update.update_id);
+                                       pending_background_events.push(
+                                               BackgroundEvent::MonitorUpdateRegeneratedOnStartup {
+                                                       counterparty_node_id: $counterparty_node_id,
+                                                       funding_txo: $funding_txo,
+                                                       update: update.clone(),
+                                               });
+                               }
+                               if $peer_state.in_flight_monitor_updates.insert($funding_txo, $chan_in_flight_upds).is_some() {
+                                       log_error!(args.logger, "Duplicate in-flight monitor update set for the same channel!");
+                                       return Err(DecodeError::InvalidValue);
+                               }
+                               max_in_flight_update_id
+                       } }
+               }
+
+               for (counterparty_id, peer_state_mtx) in per_peer_state.iter_mut() {
+                       let mut peer_state_lock = peer_state_mtx.lock().unwrap();
+                       let peer_state = &mut *peer_state_lock;
+                       for (_, chan) in peer_state.channel_by_id.iter() {
+                               // Channels that were persisted have to be funded, otherwise they should have been
+                               // discarded.
+                               let funding_txo = chan.context.get_funding_txo().ok_or(DecodeError::InvalidValue)?;
+                               let monitor = args.channel_monitors.get(&funding_txo)
+                                       .expect("We already checked for monitor presence when loading channels");
+                               let mut max_in_flight_update_id = monitor.get_latest_update_id();
+                               if let Some(in_flight_upds) = &mut in_flight_monitor_updates {
+                                       if let Some(mut chan_in_flight_upds) = in_flight_upds.remove(&(*counterparty_id, funding_txo)) {
+                                               max_in_flight_update_id = cmp::max(max_in_flight_update_id,
+                                                       handle_in_flight_updates!(*counterparty_id, chan_in_flight_upds,
+                                                               funding_txo, monitor, peer_state, ""));
+                                       }
+                               }
+                               if chan.get_latest_unblocked_monitor_update_id() > max_in_flight_update_id {
+                                       // If the channel is ahead of the monitor, return InvalidValue:
+                                       log_error!(args.logger, "A ChannelMonitor is stale compared to the current ChannelManager! This indicates a potentially-critical violation of the chain::Watch API!");
+                                       log_error!(args.logger, " The ChannelMonitor for channel {} is at update_id {} with update_id through {} in-flight",
+                                               log_bytes!(chan.context.channel_id()), monitor.get_latest_update_id(), max_in_flight_update_id);
+                                       log_error!(args.logger, " but the ChannelManager is at update_id {}.", chan.get_latest_unblocked_monitor_update_id());
+                                       log_error!(args.logger, " The chain::Watch API *requires* that monitors are persisted durably before returning,");
+                                       log_error!(args.logger, " client applications must ensure that ChannelMonitor data is always available and the latest to avoid funds loss!");
+                                       log_error!(args.logger, " Without the latest ChannelMonitor we cannot continue without risking funds.");
+                                       log_error!(args.logger, " Please ensure the chain::Watch API requirements are met and file a bug report at https://github.com/lightningdevkit/rust-lightning");
+                                       return Err(DecodeError::InvalidValue);
+                               }
+                       }
+               }
+
+               if let Some(in_flight_upds) = in_flight_monitor_updates {
+                       for ((counterparty_id, funding_txo), mut chan_in_flight_updates) in in_flight_upds {
+                               if let Some(monitor) = args.channel_monitors.get(&funding_txo) {
+                                       // Now that we've removed all the in-flight monitor updates for channels that are
+                                       // still open, we need to replay any monitor updates that are for closed channels,
+                                       // creating the neccessary peer_state entries as we go.
+                                       let peer_state_mutex = per_peer_state.entry(counterparty_id).or_insert_with(|| {
+                                               Mutex::new(peer_state_from_chans(HashMap::new()))
+                                       });
+                                       let mut peer_state = peer_state_mutex.lock().unwrap();
+                                       handle_in_flight_updates!(counterparty_id, chan_in_flight_updates,
+                                               funding_txo, monitor, peer_state, "closed ");
+                               } else {
+                                       log_error!(args.logger, "A ChannelMonitor is missing even though we have in-flight updates for it! This indicates a potentially-critical violation of the chain::Watch API!");
+                                       log_error!(args.logger, " The ChannelMonitor for channel {} is missing.",
+                                               log_bytes!(funding_txo.to_channel_id()));
+                                       log_error!(args.logger, " The chain::Watch API *requires* that monitors are persisted durably before returning,");
+                                       log_error!(args.logger, " client applications must ensure that ChannelMonitor data is always available and the latest to avoid funds loss!");
+                                       log_error!(args.logger, " Without the latest ChannelMonitor we cannot continue without risking funds.");
+                                       log_error!(args.logger, " Please ensure the chain::Watch API requirements are met and file a bug report at https://github.com/lightningdevkit/rust-lightning");
+                                       return Err(DecodeError::InvalidValue);
+                               }
+                       }
+               }
+
+               // Note that we have to do the above replays before we push new monitor updates.
+               pending_background_events.append(&mut close_background_events);
+
                {
                        // If we're tracking pending payments, ensure we haven't lost any by looking at the
                        // ChannelMonitor data for any channels for which we do not have authorative state
@@ -8582,7 +8857,7 @@ mod tests {
        use crate::ln::{PaymentPreimage, PaymentHash, PaymentSecret};
        use crate::ln::channelmanager::{inbound_payment, PaymentId, PaymentSendFailure, RecipientOnionFields, InterceptId};
        use crate::ln::functional_test_utils::*;
-       use crate::ln::msgs;
+       use crate::ln::msgs::{self, ErrorAction};
        use crate::ln::msgs::ChannelMessageHandler;
        use crate::routing::router::{PaymentParameters, RouteParameters, find_route};
        use crate::util::errors::APIError;
@@ -9534,7 +9809,94 @@ mod tests {
                get_event_msg!(nodes[1], MessageSendEvent::SendAcceptChannel, last_random_pk);
        }
 
-       #[cfg(anchors)]
+       #[test]
+       fn reject_excessively_underpaying_htlcs() {
+               let chanmon_cfg = create_chanmon_cfgs(1);
+               let node_cfg = create_node_cfgs(1, &chanmon_cfg);
+               let node_chanmgr = create_node_chanmgrs(1, &node_cfg, &[None]);
+               let node = create_network(1, &node_cfg, &node_chanmgr);
+               let sender_intended_amt_msat = 100;
+               let extra_fee_msat = 10;
+               let hop_data = msgs::OnionHopData {
+                       amt_to_forward: 100,
+                       outgoing_cltv_value: 42,
+                       format: msgs::OnionHopDataFormat::FinalNode {
+                               keysend_preimage: None,
+                               payment_metadata: None,
+                               payment_data: Some(msgs::FinalOnionHopData {
+                                       payment_secret: PaymentSecret([0; 32]), total_msat: sender_intended_amt_msat,
+                               }),
+                       }
+               };
+               // Check that if the amount we received + the penultimate hop extra fee is less than the sender
+               // intended amount, we fail the payment.
+               if let Err(crate::ln::channelmanager::ReceiveError { err_code, .. }) =
+                       node[0].node.construct_recv_pending_htlc_info(hop_data, [0; 32], PaymentHash([0; 32]),
+                               sender_intended_amt_msat - extra_fee_msat - 1, 42, None, true, Some(extra_fee_msat))
+               {
+                       assert_eq!(err_code, 19);
+               } else { panic!(); }
+
+               // If amt_received + extra_fee is equal to the sender intended amount, we're fine.
+               let hop_data = msgs::OnionHopData { // This is the same hop_data as above, OnionHopData doesn't implement Clone
+                       amt_to_forward: 100,
+                       outgoing_cltv_value: 42,
+                       format: msgs::OnionHopDataFormat::FinalNode {
+                               keysend_preimage: None,
+                               payment_metadata: None,
+                               payment_data: Some(msgs::FinalOnionHopData {
+                                       payment_secret: PaymentSecret([0; 32]), total_msat: sender_intended_amt_msat,
+                               }),
+                       }
+               };
+               assert!(node[0].node.construct_recv_pending_htlc_info(hop_data, [0; 32], PaymentHash([0; 32]),
+                       sender_intended_amt_msat - extra_fee_msat, 42, None, true, Some(extra_fee_msat)).is_ok());
+       }
+
+       #[test]
+       fn test_inbound_anchors_manual_acceptance() {
+               // Tests that we properly limit inbound channels when we have the manual-channel-acceptance
+               // flag set and (sometimes) accept channels as 0conf.
+               let mut anchors_cfg = test_default_channel_config();
+               anchors_cfg.channel_handshake_config.negotiate_anchors_zero_fee_htlc_tx = true;
+
+               let mut anchors_manual_accept_cfg = anchors_cfg.clone();
+               anchors_manual_accept_cfg.manually_accept_inbound_channels = true;
+
+               let chanmon_cfgs = create_chanmon_cfgs(3);
+               let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
+               let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs,
+                       &[Some(anchors_cfg.clone()), Some(anchors_cfg.clone()), Some(anchors_manual_accept_cfg.clone())]);
+               let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
+
+               nodes[0].node.create_channel(nodes[1].node.get_our_node_id(), 100_000, 0, 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);
+               assert!(nodes[1].node.get_and_clear_pending_events().is_empty());
+               let msg_events = nodes[1].node.get_and_clear_pending_msg_events();
+               match &msg_events[0] {
+                       MessageSendEvent::HandleError { node_id, action } => {
+                               assert_eq!(*node_id, nodes[0].node.get_our_node_id());
+                               match action {
+                                       ErrorAction::SendErrorMessage { msg } =>
+                                               assert_eq!(msg.data, "No channels with anchor outputs accepted".to_owned()),
+                                       _ => panic!("Unexpected error action"),
+                               }
+                       }
+                       _ => panic!("Unexpected event"),
+               }
+
+               nodes[2].node.handle_open_channel(&nodes[0].node.get_our_node_id(), &open_channel_msg);
+               let events = nodes[2].node.get_and_clear_pending_events();
+               match events[0] {
+                       Event::OpenChannelRequest { temporary_channel_id, .. } =>
+                               nodes[2].node.accept_inbound_channel(&temporary_channel_id, &nodes[0].node.get_our_node_id(), 23).unwrap(),
+                       _ => panic!("Unexpected event"),
+               }
+               get_event_msg!(nodes[2], MessageSendEvent::SendAcceptChannel, nodes[0].node.get_our_node_id());
+       }
+
        #[test]
        fn test_anchors_zero_fee_htlc_tx_fallback() {
                // Tests that if both nodes support anchors, but the remote node does not want to accept