Limit the number of pending un-funded inbound channel
[rust-lightning] / lightning / src / ln / channelmanager.rs
index 3b58610487f227feb24bb43f56259c630de3e989..45f45e138629d7dc6ddf2ed27b04d45e55e174ed 100644 (file)
@@ -53,7 +53,7 @@ use crate::ln::onion_utils::HTLCFailReason;
 use crate::ln::msgs::{ChannelMessageHandler, DecodeError, LightningError, MAX_VALUE_MSAT};
 #[cfg(test)]
 use crate::ln::outbound_payment;
-use crate::ln::outbound_payment::{OutboundPayments, PaymentAttempts, PendingOutboundPayment, Retry};
+use crate::ln::outbound_payment::{OutboundPayments, PaymentAttempts, PendingOutboundPayment};
 use crate::ln::wire::Encode;
 use crate::chain::keysinterface::{EntropySource, KeysManager, NodeSigner, Recipient, SignerProvider, ChannelSigner};
 use crate::util::config::{UserConfig, ChannelConfig};
@@ -70,13 +70,13 @@ use crate::prelude::*;
 use core::{cmp, mem};
 use core::cell::RefCell;
 use crate::io::Read;
-use crate::sync::{Arc, Mutex, RwLock, RwLockReadGuard, FairRwLock};
+use crate::sync::{Arc, Mutex, RwLock, RwLockReadGuard, FairRwLock, LockTestExt, LockHeldState};
 use core::sync::atomic::{AtomicUsize, Ordering};
 use core::time::Duration;
 use core::ops::Deref;
 
 // Re-export this for use in the public API.
-pub use crate::ln::outbound_payment::PaymentSendFailure;
+pub use crate::ln::outbound_payment::{PaymentSendFailure, Retry};
 
 // We hold various information about HTLC relay in the HTLC objects in Channel itself:
 //
@@ -487,6 +487,22 @@ pub(super) struct PeerState<Signer: ChannelSigner> {
        /// Messages to send to the peer - pushed to in the same lock that they are generated in (except
        /// for broadcast messages, where ordering isn't as strict).
        pub(super) pending_msg_events: Vec<MessageSendEvent>,
+       /// The peer is currently connected (i.e. we've seen a
+       /// [`ChannelMessageHandler::peer_connected`] and no corresponding
+       /// [`ChannelMessageHandler::peer_disconnected`].
+       is_connected: bool,
+}
+
+impl <Signer: ChannelSigner> PeerState<Signer> {
+       /// Indicates that a peer meets the criteria where we're ok to remove it from our storage.
+       /// If true is passed for `require_disconnected`, the function will return false if we haven't
+       /// disconnected from the node already, ie. `PeerState::is_connected` is set to `true`.
+       fn ok_to_remove(&self, require_disconnected: bool) -> bool {
+               if require_disconnected && self.is_connected {
+                       return false
+               }
+               self.channel_by_id.len() == 0
+       }
 }
 
 /// Stores a PaymentSecret and any other data we may need to validate an inbound payment is
@@ -577,6 +593,15 @@ pub type SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, M, T, F, L> = C
 /// offline for a full minute. In order to track this, you must call
 /// timer_tick_occurred roughly once per minute, though it doesn't have to be perfect.
 ///
+/// To avoid trivial DoS issues, ChannelManager limits the number of inbound connections and
+/// inbound channels without confirmed funding transactions. This may result in nodes which we do
+/// not have a channel with being unable to connect to us or open new channels with us if we have
+/// many peers with unfunded channels.
+///
+/// Because it is an indication of trust, inbound channels which we've accepted as 0conf are
+/// exempted from the count of unfunded channels. Similarly, outbound channels and connections are
+/// never limited. Please ensure you limit the count of such channels yourself.
+///
 /// Rather than using a plain ChannelManager, it is preferable to use either a SimpleArcChannelManager
 /// a SimpleRefChannelManager, for conciseness. See their documentation for more details, but
 /// essentially you should default to using a SimpleRefChannelManager, and use a
@@ -763,9 +788,8 @@ where
        /// very far in the past, and can only ever be up to two hours in the future.
        highest_seen_timestamp: AtomicUsize,
 
-       /// The bulk of our storage will eventually be here (message queues and the like). Currently
-       /// the `per_peer_state` stores our channels on a per-peer basis, as well as the peer's latest
-       /// features.
+       /// The bulk of our storage. Currently the `per_peer_state` stores our channels on a per-peer
+       /// basis, as well as the peer's latest features.
        ///
        /// If we are connected to a peer we always at least have an entry here, even if no channels
        /// are currently open with that peer.
@@ -928,6 +952,19 @@ pub(crate) const MPP_TIMEOUT_TICKS: u8 = 3;
 /// [`OutboundPayments::remove_stale_resolved_payments`].
 pub(crate) const IDEMPOTENCY_TIMEOUT_TICKS: u8 = 7;
 
+/// The maximum number of unfunded channels we can have per-peer before we start rejecting new
+/// (inbound) ones. The number of peers with unfunded channels is limited separately in
+/// [`MAX_UNFUNDED_CHANNEL_PEERS`].
+const MAX_UNFUNDED_CHANS_PER_PEER: usize = 4;
+
+/// The maximum number of peers from which we will allow pending unfunded channels. Once we reach
+/// this many peers we reject new (inbound) channels from peers with which we don't have a channel.
+const MAX_UNFUNDED_CHANNEL_PEERS: usize = 50;
+
+/// The maximum number of peers which we do not have a (funded) channel with. Once we reach this
+/// many peers we reject new (inbound) connections.
+const MAX_NO_CHANNEL_PEERS: usize = 250;
+
 /// Information needed for constructing an invoice route hint for this channel.
 #[derive(Clone, Debug, PartialEq)]
 pub struct CounterpartyForwardingInfo {
@@ -1154,6 +1191,36 @@ impl ChannelDetails {
        }
 }
 
+/// Used by [`ChannelManager::list_recent_payments`] to express the status of recent payments.
+/// These include payments that have yet to find a successful path, or have unresolved HTLCs.
+#[derive(Debug, PartialEq)]
+pub enum RecentPaymentDetails {
+       /// When a payment is still being sent and awaiting successful delivery.
+       Pending {
+               /// Hash of the payment that is currently being sent but has yet to be fulfilled or
+               /// abandoned.
+               payment_hash: PaymentHash,
+               /// Total amount (in msat, excluding fees) across all paths for this payment,
+               /// not just the amount currently inflight.
+               total_msat: u64,
+       },
+       /// When a pending payment is fulfilled, we continue tracking it until all pending HTLCs have
+       /// been resolved. Upon receiving [`Event::PaymentSent`], we delay for a few minutes before the
+       /// payment is removed from tracking.
+       Fulfilled {
+               /// Hash of the payment that was claimed. `None` for serializations of [`ChannelManager`]
+               /// made before LDK version 0.0.104.
+               payment_hash: Option<PaymentHash>,
+       },
+       /// After a payment's retries are exhausted per the provided [`Retry`], or it is explicitly
+       /// abandoned via [`ChannelManager::abandon_payment`], it is marked as abandoned until all
+       /// pending HTLCs for this payment resolve and an [`Event::PaymentFailed`] is generated.
+       Abandoned {
+               /// Hash of the payment that we have given up trying to send.
+               payment_hash: PaymentHash,
+       },
+}
+
 /// Route hints used in constructing invoices for [phantom node payents].
 ///
 /// [phantom node payments]: crate::chain::keysinterface::PhantomKeysManager
@@ -1173,13 +1240,10 @@ macro_rules! handle_error {
                match $internal {
                        Ok(msg) => Ok(msg),
                        Err(MsgHandleErrInternal { err, chan_id, shutdown_finish }) => {
-                               #[cfg(any(feature = "_test_utils", test))]
-                               {
-                                       // In testing, ensure there are no deadlocks where the lock is already held upon
-                                       // entering the macro.
-                                       debug_assert!($self.pending_events.try_lock().is_ok());
-                                       debug_assert!($self.per_peer_state.try_write().is_ok());
-                               }
+                               // In testing, ensure there are no deadlocks where the lock is already held upon
+                               // entering the macro.
+                               debug_assert_ne!($self.pending_events.held_by_thread(), LockHeldState::HeldByThread);
+                               debug_assert_ne!($self.per_peer_state.held_by_thread(), LockHeldState::HeldByThread);
 
                                let mut msg_events = Vec::with_capacity(2);
 
@@ -1213,26 +1277,6 @@ macro_rules! handle_error {
                                                let mut peer_state = peer_state_mutex.lock().unwrap();
                                                peer_state.pending_msg_events.append(&mut msg_events);
                                        }
-                                       #[cfg(any(feature = "_test_utils", test))]
-                                       {
-                                               if let None = per_peer_state.get(&$counterparty_node_id) {
-                                                       // This shouldn't occour in tests unless an unkown counterparty_node_id
-                                                       // has been passed to our message handling functions.
-                                                       let expected_error_str = format!("Can't find a peer matching the passed counterparty node_id {}", $counterparty_node_id);
-                                                       match err.action {
-                                                               msgs::ErrorAction::SendErrorMessage {
-                                                                       msg: msgs::ErrorMessage { ref channel_id, ref data }
-                                                               }
-                                                               => {
-                                                                       assert_eq!(*data, expected_error_str);
-                                                                       if let Some((err_channel_id, _user_channel_id)) = chan_id {
-                                                                               debug_assert_eq!(*channel_id, err_channel_id);
-                                                                       }
-                                                               }
-                                                               _ => debug_assert!(false, "Unexpected event"),
-                                                       }
-                                               }
-                                       }
                                }
 
                                // Return error in case higher-API need one
@@ -1562,12 +1606,10 @@ where
 
                let per_peer_state = self.per_peer_state.read().unwrap();
 
-               let peer_state_mutex_opt = per_peer_state.get(&their_network_key);
-               if let None = peer_state_mutex_opt {
-                       return Err(APIError::APIMisuseError { err: format!("Not connected to node: {}", their_network_key) });
-               }
+               let peer_state_mutex = per_peer_state.get(&their_network_key)
+                       .ok_or_else(|| APIError::APIMisuseError{ err: format!("Not connected to node: {}", their_network_key) })?;
 
-               let mut peer_state = peer_state_mutex_opt.unwrap().lock().unwrap();
+               let mut peer_state = peer_state_mutex.lock().unwrap();
                let channel = {
                        let outbound_scid_alias = self.create_and_insert_outbound_scid_alias();
                        let their_features = &peer_state.latest_features;
@@ -1605,14 +1647,13 @@ where
        }
 
        fn list_channels_with_filter<Fn: FnMut(&(&[u8; 32], &Channel<<SP::Target as SignerProvider>::Signer>)) -> bool + Copy>(&self, f: Fn) -> Vec<ChannelDetails> {
-               let mut res = Vec::new();
                // Allocate our best estimate of the number of channels we have in the `res`
                // Vec. Sadly the `short_to_chan_info` map doesn't cover channels without
                // a scid or a scid alias, and the `id_to_peer` shouldn't be used outside
                // of the ChannelMonitor handling. Therefore reallocations may still occur, but is
                // unlikely as the `short_to_chan_info` map often contains 2 entries for
                // the same channel.
-               res.reserve(self.short_to_chan_info.read().unwrap().len());
+               let mut res = Vec::with_capacity(self.short_to_chan_info.read().unwrap().len());
                {
                        let best_block_height = self.best_block.read().unwrap().height();
                        let per_peer_state = self.per_peer_state.read().unwrap();
@@ -1691,6 +1732,34 @@ where
                self.list_channels_with_filter(|&(_, ref channel)| channel.is_live())
        }
 
+       /// Returns in an undefined order recent payments that -- if not fulfilled -- have yet to find a
+       /// successful path, or have unresolved HTLCs.
+       ///
+       /// This can be useful for payments that may have been prepared, but ultimately not sent, as a
+       /// result of a crash. If such a payment exists, is not listed here, and an
+       /// [`Event::PaymentSent`] has not been received, you may consider resending the payment.
+       ///
+       /// [`Event::PaymentSent`]: events::Event::PaymentSent
+       pub fn list_recent_payments(&self) -> Vec<RecentPaymentDetails> {
+               self.pending_outbound_payments.pending_outbound_payments.lock().unwrap().iter()
+                       .filter_map(|(_, pending_outbound_payment)| match pending_outbound_payment {
+                               PendingOutboundPayment::Retryable { payment_hash, total_msat, .. } => {
+                                       Some(RecentPaymentDetails::Pending {
+                                               payment_hash: *payment_hash,
+                                               total_msat: *total_msat,
+                                       })
+                               },
+                               PendingOutboundPayment::Abandoned { payment_hash, .. } => {
+                                       Some(RecentPaymentDetails::Abandoned { payment_hash: *payment_hash })
+                               },
+                               PendingOutboundPayment::Fulfilled { payment_hash, .. } => {
+                                       Some(RecentPaymentDetails::Fulfilled { payment_hash: *payment_hash })
+                               },
+                               PendingOutboundPayment::Legacy { .. } => None
+                       })
+                       .collect()
+       }
+
        /// Helper function that issues the channel close events
        fn issue_channel_close_events(&self, channel: &Channel<<SP::Target as SignerProvider>::Signer>, closure_reason: ClosureReason) {
                let mut pending_events_lock = self.pending_events.lock().unwrap();
@@ -1714,12 +1783,10 @@ where
                let result: Result<(), _> = loop {
                        let per_peer_state = self.per_peer_state.read().unwrap();
 
-                       let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id);
-                       if let None = peer_state_mutex_opt {
-                               return Err(APIError::APIMisuseError { err: format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id) });
-                       }
+                       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_opt.unwrap().lock().unwrap();
+                       let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        match peer_state.channel_by_id.entry(channel_id.clone()) {
                                hash_map::Entry::Occupied(mut chan_entry) => {
@@ -1835,12 +1902,10 @@ where
        fn force_close_channel_with_peer(&self, channel_id: &[u8; 32], peer_node_id: &PublicKey, peer_msg: Option<&String>, broadcast: bool)
        -> Result<PublicKey, APIError> {
                let per_peer_state = self.per_peer_state.read().unwrap();
-               let peer_state_mutex_opt = per_peer_state.get(peer_node_id);
+               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 = {
-                       if let None = peer_state_mutex_opt {
-                               return Err(APIError::APIMisuseError{ err: format!("Can't find a peer matching the passed counterparty node_id {}", peer_node_id) });
-                       }
-                       let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
+                       let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        if let hash_map::Entry::Occupied(chan) = peer_state.channel_by_id.entry(channel_id.clone()) {
                                if let Some(peer_msg) = peer_msg {
@@ -1856,7 +1921,7 @@ where
                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) {
-                       let mut peer_state = peer_state_mutex_opt.unwrap().lock().unwrap();
+                       let mut peer_state = peer_state_mutex.lock().unwrap();
                        peer_state.pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
                                msg: update
                        });
@@ -2143,7 +2208,7 @@ where
                                        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 let None = peer_state_mutex_opt {
+                                               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();
@@ -2257,7 +2322,9 @@ where
        /// public, and thus should be called whenever the result is going to be passed out in a
        /// [`MessageSendEvent::BroadcastChannelUpdate`] event.
        ///
-       /// May be called with peer_state already locked!
+       /// Note that in `internal_closing_signed`, this function is called without the `peer_state`
+       /// corresponding to the channel's counterparty locked, as the channel been removed from the
+       /// storage and the `peer_state` lock has been dropped.
        fn get_channel_update_for_broadcast(&self, chan: &Channel<<SP::Target as SignerProvider>::Signer>) -> Result<msgs::ChannelUpdate, LightningError> {
                if !chan.should_announce() {
                        return Err(LightningError {
@@ -2276,7 +2343,10 @@ where
        /// is public (only returning an Err if the channel does not yet have an assigned short_id),
        /// and thus MUST NOT be called unless the recipient of the resulting message has already
        /// provided evidence that they know about the existence of the channel.
-       /// May be called with peer_state already locked!
+       ///
+       /// Note that through `internal_closing_signed`, this function is called without the
+       /// `peer_state`  corresponding to the channel's counterparty locked, as the channel been
+       /// removed from the storage and the `peer_state` lock has been dropped.
        fn get_channel_update_for_unicast(&self, chan: &Channel<<SP::Target as SignerProvider>::Signer>) -> Result<msgs::ChannelUpdate, LightningError> {
                log_trace!(self.logger, "Attempting to generate channel update for channel {}", log_bytes!(chan.channel_id()));
                let short_channel_id = match chan.get_short_channel_id().or(chan.latest_inbound_scid_alias()) {
@@ -2337,11 +2407,9 @@ where
                        };
 
                        let per_peer_state = self.per_peer_state.read().unwrap();
-                       let peer_state_mutex_opt = per_peer_state.get(&counterparty_node_id);
-                       if let None = peer_state_mutex_opt {
-                               return Err(APIError::InvalidRoute{err: "No peer matching the path's first hop found!" });
-                       }
-                       let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
+                       let peer_state_mutex = per_peer_state.get(&counterparty_node_id)
+                               .ok_or_else(|| APIError::InvalidRoute{err: "No peer matching the path's first hop found!" })?;
+                       let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        if let hash_map::Entry::Occupied(mut chan) = peer_state.channel_by_id.entry(id) {
                                match {
@@ -2415,14 +2483,19 @@ where
 
        /// Sends a payment along a given route.
        ///
-       /// Value parameters are provided via the last hop in route, see documentation for RouteHop
+       /// Value parameters are provided via the last hop in route, see documentation for [`RouteHop`]
        /// fields for more info.
        ///
+       /// May generate SendHTLCs message(s) event on success, which should be relayed (e.g. via
+       /// [`PeerManager::process_events`]).
+       ///
+       /// # Avoiding Duplicate Payments
+       ///
        /// If a pending payment is currently in-flight with the same [`PaymentId`] provided, this
        /// method will error with an [`APIError::InvalidRoute`]. Note, however, that once a payment
        /// is no longer pending (either via [`ChannelManager::abandon_payment`], or handling of an
-       /// [`Event::PaymentSent`]) LDK will not stop you from sending a second payment with the same
-       /// [`PaymentId`].
+       /// [`Event::PaymentSent`] or [`Event::PaymentFailed`]) LDK will not stop you from sending a
+       /// second payment with the same [`PaymentId`].
        ///
        /// Thus, in order to ensure duplicate payments are not sent, you should implement your own
        /// tracking of payments, including state to indicate once a payment has completed. Because you
@@ -2430,12 +2503,16 @@ where
        /// consider using the [`PaymentHash`] as the key for tracking payments. In that case, the
        /// [`PaymentId`] should be a copy of the [`PaymentHash`] bytes.
        ///
-       /// May generate SendHTLCs message(s) event on success, which should be relayed (e.g. via
-       /// [`PeerManager::process_events`]).
+       /// Additionally, in the scenario where we begin the process of sending a payment, but crash
+       /// before `send_payment` returns (or prior to [`ChannelMonitorUpdate`] persistence if you're
+       /// using [`ChannelMonitorUpdateStatus::InProgress`]), the payment may be lost on restart. See
+       /// [`ChannelManager::list_recent_payments`] for more information.
+       ///
+       /// # Possible Error States on [`PaymentSendFailure`]
        ///
        /// Each path may have a different return value, and PaymentSendValue may return a Vec with
        /// each entry matching the corresponding-index entry in the route paths, see
-       /// PaymentSendFailure for more info.
+       /// [`PaymentSendFailure`] for more info.
        ///
        /// In general, a path may raise:
        ///  * [`APIError::InvalidRoute`] when an invalid route or forwarding parameter (cltv_delta, fee,
@@ -2450,18 +2527,22 @@ where
        /// irrevocably committed to on our end. In such a case, do NOT retry the payment with a
        /// different route unless you intend to pay twice!
        ///
-       /// payment_secret is unrelated to payment_hash (or PaymentPreimage) and exists to authenticate
-       /// the sender to the recipient and prevent payment-probing (deanonymization) attacks. For
-       /// newer nodes, it will be provided to you in the invoice. If you do not have one, the Route
-       /// must not contain multiple paths as multi-path payments require a recipient-provided
-       /// payment_secret.
+       /// # A caution on `payment_secret`
+       ///
+       /// `payment_secret` is unrelated to `payment_hash` (or [`PaymentPreimage`]) and exists to
+       /// authenticate the sender to the recipient and prevent payment-probing (deanonymization)
+       /// attacks. For newer nodes, it will be provided to you in the invoice. If you do not have one,
+       /// the [`Route`] must not contain multiple paths as multi-path payments require a
+       /// recipient-provided `payment_secret`.
        ///
-       /// If a payment_secret *is* provided, we assume that the invoice had the payment_secret feature
-       /// bit set (either as required or as available). If multiple paths are present in the Route,
-       /// we assume the invoice had the basic_mpp feature set.
+       /// If a `payment_secret` *is* provided, we assume that the invoice had the payment_secret
+       /// feature bit set (either as required or as available). If multiple paths are present in the
+       /// [`Route`], we assume the invoice had the basic_mpp feature set.
        ///
        /// [`Event::PaymentSent`]: events::Event::PaymentSent
+       /// [`Event::PaymentFailed`]: events::Event::PaymentFailed
        /// [`PeerManager::process_events`]: crate::ln::peer_handler::PeerManager::process_events
+       /// [`ChannelMonitorUpdateStatus::InProgress`]: crate::chain::ChannelMonitorUpdateStatus::InProgress
        pub fn send_payment(&self, route: &Route, payment_hash: PaymentHash, payment_secret: &Option<PaymentSecret>, payment_id: PaymentId) -> Result<(), PaymentSendFailure> {
                let best_block_height = self.best_block.read().unwrap().height();
                self.pending_outbound_payments
@@ -2476,7 +2557,7 @@ where
                let best_block_height = self.best_block.read().unwrap().height();
                self.pending_outbound_payments
                        .send_payment(payment_hash, payment_secret, payment_id, retry_strategy, route_params,
-                               &self.router, self.list_usable_channels(), self.compute_inflight_htlcs(),
+                               &self.router, self.list_usable_channels(), || self.compute_inflight_htlcs(),
                                &self.entropy_source, &self.node_signer, best_block_height, &self.logger,
                                |path, payment_params, payment_hash, payment_secret, total_value, cur_height, payment_id, keysend_preimage, session_priv|
                                self.send_payment_along_path(path, payment_params, payment_hash, payment_secret, total_value, cur_height, payment_id, keysend_preimage, session_priv))
@@ -2493,52 +2574,29 @@ where
        #[cfg(test)]
        pub(crate) fn test_add_new_pending_payment(&self, payment_hash: PaymentHash, payment_secret: Option<PaymentSecret>, payment_id: PaymentId, route: &Route) -> Result<Vec<[u8; 32]>, PaymentSendFailure> {
                let best_block_height = self.best_block.read().unwrap().height();
-               self.pending_outbound_payments.test_add_new_pending_payment(payment_hash, payment_secret, payment_id, route, Retry::Attempts(0), &self.entropy_source, best_block_height)
+               self.pending_outbound_payments.test_add_new_pending_payment(payment_hash, payment_secret, payment_id, route, None, &self.entropy_source, best_block_height)
        }
 
 
-       /// Retries a payment along the given [`Route`].
+       /// Signals that no further retries for the given payment should occur. Useful if you have a
+       /// pending outbound payment with retries remaining, but wish to stop retrying the payment before
+       /// retries are exhausted.
        ///
-       /// Errors returned are a superset of those returned from [`send_payment`], so see
-       /// [`send_payment`] documentation for more details on errors. This method will also error if the
-       /// retry amount puts the payment more than 10% over the payment's total amount, if the payment
-       /// for the given `payment_id` cannot be found (likely due to timeout or success), or if
-       /// further retries have been disabled with [`abandon_payment`].
-       ///
-       /// [`send_payment`]: [`ChannelManager::send_payment`]
-       /// [`abandon_payment`]: [`ChannelManager::abandon_payment`]
-       pub fn retry_payment(&self, route: &Route, payment_id: PaymentId) -> Result<(), PaymentSendFailure> {
-               let best_block_height = self.best_block.read().unwrap().height();
-               self.pending_outbound_payments.retry_payment_with_route(route, payment_id, &self.entropy_source, &self.node_signer, best_block_height,
-                       |path, payment_params, payment_hash, payment_secret, total_value, cur_height, payment_id, keysend_preimage, session_priv|
-                       self.send_payment_along_path(path, payment_params, payment_hash, payment_secret, total_value, cur_height, payment_id, keysend_preimage, session_priv))
-       }
-
-       /// Signals that no further retries for the given payment will occur.
-       ///
-       /// After this method returns, no future calls to [`retry_payment`] for the given `payment_id`
-       /// are allowed. If no [`Event::PaymentFailed`] event had been generated before, one will be
-       /// generated as soon as there are no remaining pending HTLCs for this payment.
+       /// If no [`Event::PaymentFailed`] event had been generated before, one will be generated as soon
+       /// as there are no remaining pending HTLCs for this payment.
        ///
        /// Note that calling this method does *not* prevent a payment from succeeding. You must still
        /// wait until you receive either a [`Event::PaymentFailed`] or [`Event::PaymentSent`] event to
        /// determine the ultimate status of a payment.
        ///
        /// If an [`Event::PaymentFailed`] event is generated and we restart without this
-       /// [`ChannelManager`] having been persisted, the payment may still be in the pending state
-       /// upon restart. This allows further calls to [`retry_payment`] (and requiring a second call
-       /// to [`abandon_payment`] to mark the payment as failed again). Otherwise, future calls to
-       /// [`retry_payment`] will fail with [`PaymentSendFailure::ParameterError`].
+       /// [`ChannelManager`] having been persisted, another [`Event::PaymentFailed`] may be generated.
        ///
-       /// [`abandon_payment`]: Self::abandon_payment
-       /// [`retry_payment`]: Self::retry_payment
        /// [`Event::PaymentFailed`]: events::Event::PaymentFailed
        /// [`Event::PaymentSent`]: events::Event::PaymentSent
        pub fn abandon_payment(&self, payment_id: PaymentId) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);
-               if let Some(payment_failed_ev) = self.pending_outbound_payments.abandon_payment(payment_id) {
-                       self.pending_events.lock().unwrap().push(payment_failed_ev);
-               }
+               self.pending_outbound_payments.abandon_payment(payment_id, &self.pending_events);
        }
 
        /// Send a spontaneous payment, which is a payment that does not require the recipient to have
@@ -2558,7 +2616,26 @@ where
        /// [`send_payment`]: Self::send_payment
        pub fn send_spontaneous_payment(&self, route: &Route, payment_preimage: Option<PaymentPreimage>, payment_id: PaymentId) -> Result<PaymentHash, PaymentSendFailure> {
                let best_block_height = self.best_block.read().unwrap().height();
-               self.pending_outbound_payments.send_spontaneous_payment(route, payment_preimage, payment_id, &self.entropy_source, &self.node_signer, best_block_height,
+               self.pending_outbound_payments.send_spontaneous_payment_with_route(
+                       route, payment_preimage, payment_id, &self.entropy_source, &self.node_signer,
+                       best_block_height,
+                       |path, payment_params, payment_hash, payment_secret, total_value, cur_height, payment_id, keysend_preimage, session_priv|
+                       self.send_payment_along_path(path, payment_params, payment_hash, payment_secret, total_value, cur_height, payment_id, keysend_preimage, session_priv))
+       }
+
+       /// Similar to [`ChannelManager::send_spontaneous_payment`], but will automatically find a route
+       /// based on `route_params` and retry failed payment paths based on `retry_strategy`.
+       ///
+       /// See [`PaymentParameters::for_keysend`] for help in constructing `route_params` for spontaneous
+       /// payments.
+       ///
+       /// [`PaymentParameters::for_keysend`]: crate::routing::router::PaymentParameters::for_keysend
+       pub fn send_spontaneous_payment_with_retry(&self, payment_preimage: Option<PaymentPreimage>, payment_id: PaymentId, route_params: RouteParameters, retry_strategy: Retry) -> Result<PaymentHash, PaymentSendFailure> {
+               let best_block_height = self.best_block.read().unwrap().height();
+               self.pending_outbound_payments.send_spontaneous_payment(payment_preimage, payment_id,
+                       retry_strategy, route_params, &self.router, self.list_usable_channels(),
+                       || self.compute_inflight_htlcs(),  &self.entropy_source, &self.node_signer, best_block_height,
+                       &self.logger,
                        |path, payment_params, payment_hash, payment_secret, total_value, cur_height, payment_id, keysend_preimage, session_priv|
                        self.send_payment_along_path(path, payment_params, payment_hash, payment_secret, total_value, cur_height, payment_id, keysend_preimage, session_priv))
        }
@@ -2586,12 +2663,10 @@ where
                &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();
-               let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id);
-               if let None = peer_state_mutex_opt {
-                       return Err(APIError::ChannelUnavailable { err: format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id) })
-               }
+               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_opt.unwrap().lock().unwrap();
+               let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                let (chan, msg) = {
                        let (res, chan) = {
@@ -2613,7 +2688,7 @@ where
                                        (chan, funding_msg)
                                },
                                Err(_) => { return Err(APIError::ChannelUnavailable {
-                                       err: "Error deriving keys or signing initial commitment transactions - either our RNG or our counterparty's RNG is broken or the Signer refused to sign".to_owned()
+                                       err: "Signer refused to sign the initial commitment transaction".to_owned()
                                }) },
                        }
                };
@@ -2757,11 +2832,9 @@ where
                        &self.total_consistency_lock, &self.persistence_notifier,
                );
                let per_peer_state = self.per_peer_state.read().unwrap();
-               let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id);
-               if let None = peer_state_mutex_opt {
-                       return Err(APIError::APIMisuseError{ err: format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id) });
-               }
-               let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().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;
                for channel_id in channel_ids {
                        if !peer_state.channel_by_id.contains_key(channel_id) {
@@ -2814,24 +2887,22 @@ where
 
                let next_hop_scid = {
                        let peer_state_lock = self.per_peer_state.read().unwrap();
-                       if let Some(peer_state_mutex) = peer_state_lock.get(&next_node_id) {
-                               let mut peer_state_lock = peer_state_mutex.lock().unwrap();
-                               let peer_state = &mut *peer_state_lock;
-                               match peer_state.channel_by_id.get(next_hop_channel_id) {
-                                       Some(chan) => {
-                                               if !chan.is_usable() {
-                                                       return Err(APIError::ChannelUnavailable {
-                                                               err: format!("Channel with id {} not fully established", log_bytes!(*next_hop_channel_id))
-                                                       })
-                                               }
-                                               chan.get_short_channel_id().unwrap_or(chan.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)
-                                       })
-                               }
-                       } else {
-                               return Err(APIError::APIMisuseError{ err: format!("Can't find a peer matching the passed counterparty node_id {}", next_node_id) });
+                       let peer_state_mutex = peer_state_lock.get(&next_node_id)
+                               .ok_or_else(|| APIError::ChannelUnavailable { err: format!("Can't find a peer matching the passed counterparty node_id {}", next_node_id) })?;
+                       let mut peer_state_lock = peer_state_mutex.lock().unwrap();
+                       let peer_state = &mut *peer_state_lock;
+                       match peer_state.channel_by_id.get(next_hop_channel_id) {
+                               Some(chan) => {
+                                       if !chan.is_usable() {
+                                               return Err(APIError::ChannelUnavailable {
+                                                       err: format!("Channel with id {} not fully established", log_bytes!(*next_hop_channel_id))
+                                               })
+                                       }
+                                       chan.get_short_channel_id().unwrap_or(chan.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)
+                               })
                        }
                };
 
@@ -3011,7 +3082,7 @@ where
                                        };
                                        let per_peer_state = self.per_peer_state.read().unwrap();
                                        let peer_state_mutex_opt = per_peer_state.get(&counterparty_node_id);
-                                       if let None = peer_state_mutex_opt {
+                                       if peer_state_mutex_opt.is_none() {
                                                forwarding_channel_not_found!();
                                                continue;
                                        }
@@ -3298,7 +3369,8 @@ where
 
                let best_block_height = self.best_block.read().unwrap().height();
                self.pending_outbound_payments.check_retry_payments(&self.router, || self.list_usable_channels(),
-                       || self.compute_inflight_htlcs(), &self.entropy_source, &self.node_signer, best_block_height, &self.logger,
+                       || self.compute_inflight_htlcs(), &self.entropy_source, &self.node_signer, best_block_height,
+                       &self.pending_events, &self.logger,
                        |path, payment_params, payment_hash, payment_secret, total_value, cur_height, payment_id, keysend_preimage, session_priv|
                        self.send_payment_along_path(path, payment_params, payment_hash, payment_secret, total_value, cur_height, payment_id, keysend_preimage, session_priv));
 
@@ -3403,6 +3475,7 @@ where
        ///    the channel.
        ///  * Expiring a channel's previous `ChannelConfig` if necessary to only allow forwarding HTLCs
        ///    with the current `ChannelConfig`.
+       ///  * Removing peers which have disconnected but and no longer have any channels.
        ///
        /// Note that this may cause reentrancy through `chain::Watch::update_channel` calls or feerate
        /// estimate fetches.
@@ -3415,19 +3488,21 @@ where
 
                        let mut handle_errors: Vec<(Result<(), _>, _)> = Vec::new();
                        let mut timed_out_mpp_htlcs = Vec::new();
+                       let mut pending_peers_awaiting_removal = Vec::new();
                        {
                                let per_peer_state = self.per_peer_state.read().unwrap();
                                for (counterparty_node_id, peer_state_mutex) in per_peer_state.iter() {
                                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                                        let peer_state = &mut *peer_state_lock;
                                        let pending_msg_events = &mut peer_state.pending_msg_events;
+                                       let counterparty_node_id = *counterparty_node_id;
                                        peer_state.channel_by_id.retain(|chan_id, chan| {
                                                let chan_needs_persist = self.update_channel_fee(chan_id, chan, new_feerate);
                                                if chan_needs_persist == NotifyOption::DoPersist { should_persist = NotifyOption::DoPersist; }
 
                                                if let Err(e) = chan.timer_check_closing_negotiation_progress() {
                                                        let (needs_close, err) = convert_chan_err!(self, e, chan, chan_id);
-                                                       handle_errors.push((Err(err), *counterparty_node_id));
+                                                       handle_errors.push((Err(err), counterparty_node_id));
                                                        if needs_close { return false; }
                                                }
 
@@ -3461,6 +3536,36 @@ where
 
                                                true
                                        });
+                                       if peer_state.ok_to_remove(true) {
+                                               pending_peers_awaiting_removal.push(counterparty_node_id);
+                                       }
+                               }
+                       }
+
+                       // When a peer disconnects but still has channels, the peer's `peer_state` entry in the
+                       // `per_peer_state` is not removed by the `peer_disconnected` function. If the channels
+                       // of to that peer is later closed while still being disconnected (i.e. force closed),
+                       // we therefore need to remove the peer from `peer_state` separately.
+                       // To avoid having to take the `per_peer_state` `write` lock once the channels are
+                       // closed, we instead remove such peers awaiting removal here on a timer, to limit the
+                       // negative effects on parallelism as much as possible.
+                       if pending_peers_awaiting_removal.len() > 0 {
+                               let mut per_peer_state = self.per_peer_state.write().unwrap();
+                               for counterparty_node_id in pending_peers_awaiting_removal {
+                                       match per_peer_state.entry(counterparty_node_id) {
+                                               hash_map::Entry::Occupied(entry) => {
+                                                       // Remove the entry if the peer is still disconnected and we still
+                                                       // have no channels to the peer.
+                                                       let remove_entry = {
+                                                               let peer_state = entry.get().lock().unwrap();
+                                                               peer_state.ok_to_remove(true)
+                                                       };
+                                                       if remove_entry {
+                                                               entry.remove_entry();
+                                                       }
+                                               },
+                                               hash_map::Entry::Vacant(_) => { /* The PeerState has already been removed */ }
+                                       }
                                }
                        }
 
@@ -3636,17 +3741,12 @@ where
        /// Fails an HTLC backwards to the sender of it to us.
        /// Note that we do not assume that channels corresponding to failed HTLCs are still available.
        fn fail_htlc_backwards_internal(&self, source: &HTLCSource, payment_hash: &PaymentHash, onion_error: &HTLCFailReason, destination: HTLCDestination) {
-               #[cfg(any(feature = "_test_utils", test))]
-               {
-                       // Ensure that no peer state channel storage lock is not held when calling this
-                       // function.
-                       // This ensures that future code doesn't introduce a lock_order requirement for
-                       // `forward_htlcs` to be locked after the `per_peer_state` peer locks, which calling
-                       // this function with any `per_peer_state` peer lock aquired would.
-                       let per_peer_state = self.per_peer_state.read().unwrap();
-                       for (_, peer) in per_peer_state.iter() {
-                               debug_assert!(peer.try_lock().is_ok());
-                       }
+               // Ensure that no peer state channel storage lock is held when calling this function.
+               // This ensures that future code doesn't introduce a lock-order requirement for
+               // `forward_htlcs` to be locked after the `per_peer_state` peer locks, which calling
+               // this function with any `per_peer_state` peer lock acquired would.
+               for (_, peer) in self.per_peer_state.read().unwrap().iter() {
+                       debug_assert_ne!(peer.held_by_thread(), LockHeldState::HeldByThread);
                }
 
                //TODO: There is a timing attack here where if a node fails an HTLC back to us they can
@@ -3659,16 +3759,19 @@ where
                // being fully configured. See the docs for `ChannelManagerReadArgs` for more.
                match source {
                        HTLCSource::OutboundRoute { ref path, ref session_priv, ref payment_id, ref payment_params, .. } => {
-                               self.pending_outbound_payments.fail_htlc(source, payment_hash, onion_error, path, session_priv, payment_id, payment_params, self.probing_cookie_secret, &self.secp_ctx, &self.pending_events, &self.logger);
+                               if self.pending_outbound_payments.fail_htlc(source, payment_hash, onion_error, path,
+                                       session_priv, payment_id, payment_params, self.probing_cookie_secret, &self.secp_ctx,
+                                       &self.pending_events, &self.logger)
+                               { self.push_pending_forwards_ev(); }
                        },
                        HTLCSource::PreviousHopData(HTLCPreviousHopData { ref short_channel_id, ref htlc_id, ref incoming_packet_shared_secret, ref phantom_shared_secret, ref outpoint }) => {
                                log_trace!(self.logger, "Failing HTLC with payment_hash {} backwards from us with {:?}", log_bytes!(payment_hash.0), onion_error);
                                let err_packet = onion_error.get_encrypted_failure_packet(incoming_packet_shared_secret, phantom_shared_secret);
 
-                               let mut forward_event = None;
+                               let mut push_forward_ev = false;
                                let mut forward_htlcs = self.forward_htlcs.lock().unwrap();
                                if forward_htlcs.is_empty() {
-                                       forward_event = Some(Duration::from_millis(MIN_HTLC_RELAY_HOLDING_CELL_MILLIS));
+                                       push_forward_ev = true;
                                }
                                match forward_htlcs.entry(*short_channel_id) {
                                        hash_map::Entry::Occupied(mut entry) => {
@@ -3679,12 +3782,8 @@ where
                                        }
                                }
                                mem::drop(forward_htlcs);
+                               if push_forward_ev { self.push_pending_forwards_ev(); }
                                let mut pending_events = self.pending_events.lock().unwrap();
-                               if let Some(time) = forward_event {
-                                       pending_events.push(events::Event::PendingHTLCsForwardable {
-                                               time_forwardable: time
-                                       });
-                               }
                                pending_events.push(events::Event::HTLCHandlingFailed {
                                        prev_channel_id: outpoint.to_channel_id(),
                                        failed_next_destination: destination,
@@ -3761,7 +3860,7 @@ where
                let mut expected_amt_msat = None;
                let mut valid_mpp = true;
                let mut errs = Vec::new();
-               let mut per_peer_state = Some(self.per_peer_state.read().unwrap());
+               let per_peer_state = self.per_peer_state.read().unwrap();
                for htlc in sources.iter() {
                        let (counterparty_node_id, chan_id) = match self.short_to_chan_info.read().unwrap().get(&htlc.prev_hop.short_channel_id) {
                                Some((cp_id, chan_id)) => (cp_id.clone(), chan_id.clone()),
@@ -3771,16 +3870,16 @@ where
                                }
                        };
 
-                       if let None = per_peer_state.as_ref().unwrap().get(&counterparty_node_id) {
+                       let peer_state_mutex_opt = per_peer_state.get(&counterparty_node_id);
+                       if peer_state_mutex_opt.is_none() {
                                valid_mpp = false;
                                break;
                        }
 
-                       let peer_state_mutex = per_peer_state.as_ref().unwrap().get(&counterparty_node_id).unwrap();
-                       let mut peer_state_lock = peer_state_mutex.lock().unwrap();
+                       let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
 
-                       if let None = peer_state.channel_by_id.get(&chan_id) {
+                       if peer_state.channel_by_id.get(&chan_id).is_none() {
                                valid_mpp = false;
                                break;
                        }
@@ -3806,14 +3905,13 @@ where
 
                        claimable_amt_msat += htlc.value;
                }
+               mem::drop(per_peer_state);
                if sources.is_empty() || expected_amt_msat.is_none() {
-                       mem::drop(per_peer_state);
                        self.claimable_payments.lock().unwrap().pending_claiming_payments.remove(&payment_hash);
                        log_info!(self.logger, "Attempted to claim an incomplete payment which no longer had any available HTLCs!");
                        return;
                }
                if claimable_amt_msat != expected_amt_msat.unwrap() {
-                       mem::drop(per_peer_state);
                        self.claimable_payments.lock().unwrap().pending_claiming_payments.remove(&payment_hash);
                        log_info!(self.logger, "Attempted to claim an incomplete payment, expected {} msat, had {} available to claim.",
                                expected_amt_msat.unwrap(), claimable_amt_msat);
@@ -3821,8 +3919,7 @@ where
                }
                if valid_mpp {
                        for htlc in sources.drain(..) {
-                               if per_peer_state.is_none() { per_peer_state = Some(self.per_peer_state.read().unwrap()); }
-                               if let Err((pk, err)) = self.claim_funds_from_hop(per_peer_state.take().unwrap(),
+                               if let Err((pk, err)) = self.claim_funds_from_hop(
                                        htlc.prev_hop, payment_preimage,
                                        |_| Some(MonitorUpdateCompletionAction::PaymentClaimed { payment_hash }))
                                {
@@ -3834,7 +3931,6 @@ where
                                }
                        }
                }
-               mem::drop(per_peer_state);
                if !valid_mpp {
                        for htlc in sources.drain(..) {
                                let mut htlc_msat_height_data = htlc.value.to_be_bytes().to_vec();
@@ -3855,11 +3951,11 @@ where
        }
 
        fn claim_funds_from_hop<ComplFunc: FnOnce(Option<u64>) -> Option<MonitorUpdateCompletionAction>>(&self,
-               per_peer_state_lock: RwLockReadGuard<HashMap<PublicKey, Mutex<PeerState<<SP::Target as SignerProvider>::Signer>>>>,
                prev_hop: HTLCPreviousHopData, payment_preimage: PaymentPreimage, completion_action: ComplFunc)
        -> Result<(), (PublicKey, MsgHandleErrInternal)> {
                //TODO: Delay the claimed_funds relaying just like we do outbound relay!
 
+               let per_peer_state = self.per_peer_state.read().unwrap();
                let chan_id = prev_hop.outpoint.to_channel_id();
 
                let counterparty_node_id_opt = match self.short_to_chan_info.read().unwrap().get(&prev_hop.short_channel_id) {
@@ -3867,83 +3963,76 @@ where
                        None => None
                };
 
-               let (found_channel, mut peer_state_opt) = if counterparty_node_id_opt.is_some() && per_peer_state_lock.get(&counterparty_node_id_opt.unwrap()).is_some() {
-                       let peer_mutex = per_peer_state_lock.get(&counterparty_node_id_opt.unwrap()).unwrap();
-                       let peer_state = peer_mutex.lock().unwrap();
-                       let found_channel = peer_state.channel_by_id.contains_key(&chan_id);
-                       (found_channel, Some(peer_state))
-               }  else { (false, None) };
-
-               if found_channel {
-                       let peer_state = &mut *peer_state_opt.as_mut().unwrap();
-                       if let hash_map::Entry::Occupied(mut chan) = peer_state.channel_by_id.entry(chan_id) {
-                               let counterparty_node_id = chan.get().get_counterparty_node_id();
-                               match chan.get_mut().get_update_fulfill_htlc_and_commit(prev_hop.htlc_id, payment_preimage, &self.logger) {
-                                       Ok(msgs_monitor_option) => {
-                                               if let UpdateFulfillCommitFetch::NewClaim { msgs, htlc_value_msat, monitor_update } = msgs_monitor_option {
-                                                       match self.chain_monitor.update_channel(chan.get().get_funding_txo().unwrap(), &monitor_update) {
-                                                               ChannelMonitorUpdateStatus::Completed => {},
-                                                               e => {
-                                                                       log_given_level!(self.logger, if e == ChannelMonitorUpdateStatus::PermanentFailure { Level::Error } else { Level::Debug },
-                                                                               "Failed to update channel monitor with preimage {:?}: {:?}",
-                                                                               payment_preimage, e);
-                                                                       let err = handle_monitor_update_res!(self, e, chan, RAACommitmentOrder::CommitmentFirst, false, msgs.is_some()).unwrap_err();
-                                                                       mem::drop(peer_state_opt);
-                                                                       mem::drop(per_peer_state_lock);
-                                                                       self.handle_monitor_update_completion_actions(completion_action(Some(htlc_value_msat)));
-                                                                       return Err((counterparty_node_id, err));
-                                                               }
-                                                       }
-                                                       if let Some((msg, commitment_signed)) = msgs {
-                                                               log_debug!(self.logger, "Claiming funds for HTLC with preimage {} resulted in a commitment_signed for channel {}",
-                                                                       log_bytes!(payment_preimage.0), log_bytes!(chan.get().channel_id()));
-                                                               peer_state.pending_msg_events.push(events::MessageSendEvent::UpdateHTLCs {
-                                                                       node_id: counterparty_node_id,
-                                                                       updates: msgs::CommitmentUpdate {
-                                                                               update_add_htlcs: Vec::new(),
-                                                                               update_fulfill_htlcs: vec![msg],
-                                                                               update_fail_htlcs: Vec::new(),
-                                                                               update_fail_malformed_htlcs: Vec::new(),
-                                                                               update_fee: None,
-                                                                               commitment_signed,
-                                                                       }
-                                                               });
-                                                       }
-                                                       mem::drop(peer_state_opt);
-                                                       mem::drop(per_peer_state_lock);
-                                                       self.handle_monitor_update_completion_actions(completion_action(Some(htlc_value_msat)));
-                                                       Ok(())
-                                               } else {
-                                                       Ok(())
-                                               }
-                                       },
-                                       Err((e, monitor_update)) => {
+               let mut peer_state_opt = counterparty_node_id_opt.as_ref().map(
+                       |counterparty_node_id| per_peer_state.get(counterparty_node_id).map(
+                               |peer_mutex| peer_mutex.lock().unwrap()
+                       )
+               ).unwrap_or(None);
+
+               if let Some(hash_map::Entry::Occupied(mut chan)) = peer_state_opt.as_mut().map(|peer_state| peer_state.channel_by_id.entry(chan_id))
+               {
+                       let counterparty_node_id = chan.get().get_counterparty_node_id();
+                       match chan.get_mut().get_update_fulfill_htlc_and_commit(prev_hop.htlc_id, payment_preimage, &self.logger) {
+                               Ok(msgs_monitor_option) => {
+                                       if let UpdateFulfillCommitFetch::NewClaim { msgs, htlc_value_msat, monitor_update } = msgs_monitor_option {
                                                match self.chain_monitor.update_channel(chan.get().get_funding_txo().unwrap(), &monitor_update) {
                                                        ChannelMonitorUpdateStatus::Completed => {},
                                                        e => {
-                                                               // TODO: This needs to be handled somehow - if we receive a monitor update
-                                                               // with a preimage we *must* somehow manage to propagate it to the upstream
-                                                               // channel, or we must have an ability to receive the same update and try
-                                                               // again on restart.
-                                                               log_given_level!(self.logger, if e == ChannelMonitorUpdateStatus::PermanentFailure { Level::Error } else { Level::Info },
-                                                                       "Failed to update channel monitor with preimage {:?} immediately prior to force-close: {:?}",
+                                                               log_given_level!(self.logger, if e == ChannelMonitorUpdateStatus::PermanentFailure { Level::Error } else { Level::Debug },
+                                                                       "Failed to update channel monitor with preimage {:?}: {:?}",
                                                                        payment_preimage, e);
-                                                       },
+                                                               let err = handle_monitor_update_res!(self, e, chan, RAACommitmentOrder::CommitmentFirst, false, msgs.is_some()).unwrap_err();
+                                                               mem::drop(peer_state_opt);
+                                                               mem::drop(per_peer_state);
+                                                               self.handle_monitor_update_completion_actions(completion_action(Some(htlc_value_msat)));
+                                                               return Err((counterparty_node_id, err));
+                                                       }
                                                }
-                                               let (drop, res) = convert_chan_err!(self, e, chan.get_mut(), &chan_id);
-                                               if drop {
-                                                       chan.remove_entry();
+                                               if let Some((msg, commitment_signed)) = msgs {
+                                                       log_debug!(self.logger, "Claiming funds for HTLC with preimage {} resulted in a commitment_signed for channel {}",
+                                                               log_bytes!(payment_preimage.0), log_bytes!(chan.get().channel_id()));
+                                                       peer_state_opt.as_mut().unwrap().pending_msg_events.push(events::MessageSendEvent::UpdateHTLCs {
+                                                               node_id: counterparty_node_id,
+                                                               updates: msgs::CommitmentUpdate {
+                                                                       update_add_htlcs: Vec::new(),
+                                                                       update_fulfill_htlcs: vec![msg],
+                                                                       update_fail_htlcs: Vec::new(),
+                                                                       update_fail_malformed_htlcs: Vec::new(),
+                                                                       update_fee: None,
+                                                                       commitment_signed,
+                                                               }
+                                                       });
                                                }
                                                mem::drop(peer_state_opt);
-                                               mem::drop(per_peer_state_lock);
-                                               self.handle_monitor_update_completion_actions(completion_action(None));
-                                               Err((counterparty_node_id, res))
-                                       },
-                               }
-                       } else {
-                               // We've held the peer_state mutex since finding the channel and setting
-                               // found_channel to true, so the channel can't have been dropped.
-                               unreachable!()
+                                               mem::drop(per_peer_state);
+                                               self.handle_monitor_update_completion_actions(completion_action(Some(htlc_value_msat)));
+                                               Ok(())
+                                       } else {
+                                               Ok(())
+                                       }
+                               },
+                               Err((e, monitor_update)) => {
+                                       match self.chain_monitor.update_channel(chan.get().get_funding_txo().unwrap(), &monitor_update) {
+                                               ChannelMonitorUpdateStatus::Completed => {},
+                                               e => {
+                                                       // TODO: This needs to be handled somehow - if we receive a monitor update
+                                                       // with a preimage we *must* somehow manage to propagate it to the upstream
+                                                       // channel, or we must have an ability to receive the same update and try
+                                                       // again on restart.
+                                                       log_given_level!(self.logger, if e == ChannelMonitorUpdateStatus::PermanentFailure { Level::Error } else { Level::Info },
+                                                               "Failed to update channel monitor with preimage {:?} immediately prior to force-close: {:?}",
+                                                               payment_preimage, e);
+                                               },
+                                       }
+                                       let (drop, res) = convert_chan_err!(self, e, chan.get_mut(), &chan_id);
+                                       if drop {
+                                               chan.remove_entry();
+                                       }
+                                       mem::drop(peer_state_opt);
+                                       mem::drop(per_peer_state);
+                                       self.handle_monitor_update_completion_actions(completion_action(None));
+                                       Err((counterparty_node_id, res))
+                               },
                        }
                } else {
                        let preimage_update = ChannelMonitorUpdate {
@@ -3964,7 +4053,7 @@ where
                                        payment_preimage, update_res);
                        }
                        mem::drop(peer_state_opt);
-                       mem::drop(per_peer_state_lock);
+                       mem::drop(per_peer_state);
                        // Note that we do process the completion action here. This totally could be a
                        // duplicate claim, but we have no way of knowing without interrogating the
                        // `ChannelMonitor` we've provided the above update to. Instead, note that `Event`s are
@@ -3986,7 +4075,7 @@ where
                        },
                        HTLCSource::PreviousHopData(hop_data) => {
                                let prev_outpoint = hop_data.outpoint;
-                               let res = self.claim_funds_from_hop(self.per_peer_state.read().unwrap(), hop_data, payment_preimage,
+                               let res = self.claim_funds_from_hop(hop_data, payment_preimage,
                                        |htlc_claim_value_msat| {
                                                if let Some(forwarded_htlc_value) = forwarded_htlc_value_msat {
                                                        let fee_earned_msat = if let Some(claimed_htlc_value) = htlc_claim_value_msat {
@@ -4118,7 +4207,7 @@ where
                        let per_peer_state = self.per_peer_state.read().unwrap();
                        let mut peer_state_lock;
                        let peer_state_mutex_opt = per_peer_state.get(&counterparty_node_id);
-                       if let None = peer_state_mutex_opt { return }
+                       if peer_state_mutex_opt.is_none() { return }
                        peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        let mut channel = {
@@ -4207,13 +4296,13 @@ 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.total_consistency_lock, &self.persistence_notifier);
 
+               let peers_without_funded_channels = self.peers_without_funded_channels(|peer| !peer.channel_by_id.is_empty());
                let per_peer_state = self.per_peer_state.read().unwrap();
-               let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id);
-               if let None = peer_state_mutex_opt {
-                       return Err(APIError::APIMisuseError { err: format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id) });
-               }
-               let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().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()) {
                        hash_map::Entry::Occupied(mut channel) => {
                                if !channel.get().inbound_is_awaiting_accept() {
@@ -4231,6 +4320,21 @@ where
                                        peer_state.pending_msg_events.push(send_msg_err_event);
                                        let _ = remove_channel!(self, channel);
                                        return Err(APIError::APIMisuseError { err: "Please use accept_inbound_channel_from_trusted_peer_0conf to accept channels with zero confirmations.".to_owned() });
+                               } else {
+                                       // 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 is_only_peer_channel && peers_without_funded_channels >= MAX_UNFUNDED_CHANNEL_PEERS {
+                                               let send_msg_err_event = events::MessageSendEvent::HandleError {
+                                                       node_id: channel.get().get_counterparty_node_id(),
+                                                       action: msgs::ErrorAction::SendErrorMessage{
+                                                               msg: msgs::ErrorMessage { channel_id: temporary_channel_id.clone(), data: "Have too many peers with unfunded channels, not accepting new ones".to_owned(), }
+                                                       }
+                                               };
+                                               peer_state.pending_msg_events.push(send_msg_err_event);
+                                               let _ = remove_channel!(self, channel);
+                                               return Err(APIError::APIMisuseError { err: "Too many peers with unfunded channels, refusing to accept new ones".to_owned() });
+                                       }
                                }
 
                                peer_state.pending_msg_events.push(events::MessageSendEvent::SendAcceptChannel {
@@ -4245,6 +4349,43 @@ where
                Ok(())
        }
 
+       /// Gets the number of peers which match the given filter and do not have any funded, outbound,
+       /// or 0-conf channels.
+       ///
+       /// The filter is called for each peer and provided with the number of unfunded, inbound, and
+       /// non-0-conf channels we have with the peer.
+       fn peers_without_funded_channels<Filter>(&self, maybe_count_peer: Filter) -> usize
+       where Filter: Fn(&PeerState<<SP::Target as SignerProvider>::Signer>) -> bool {
+               let mut peers_without_funded_channels = 0;
+               let best_block_height = self.best_block.read().unwrap().height();
+               {
+                       let peer_state_lock = self.per_peer_state.read().unwrap();
+                       for (_, peer_mtx) in peer_state_lock.iter() {
+                               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() {
+                                       peers_without_funded_channels += 1;
+                               }
+                       }
+               }
+               return peers_without_funded_channels;
+       }
+
+       fn unfunded_channel_count(
+               peer: &PeerState<<SP::Target as SignerProvider>::Signer>, best_block_height: u32
+       ) -> usize {
+               let mut num_unfunded_channels = 0;
+               for (_, chan) in peer.channel_by_id.iter() {
+                       if !chan.is_outbound() && chan.minimum_depth().unwrap_or(1) != 0 &&
+                               chan.get_funding_tx_confirmations(best_block_height) == 0
+                       {
+                               num_unfunded_channels += 1;
+                       }
+               }
+               num_unfunded_channels
+       }
+
        fn internal_open_channel(&self, counterparty_node_id: &PublicKey, msg: &msgs::OpenChannel) -> Result<(), MsgHandleErrInternal> {
                if msg.chain_hash != self.genesis_hash {
                        return Err(MsgHandleErrInternal::send_err_msg_no_close("Unknown genesis block hash".to_owned(), msg.temporary_channel_id.clone()));
@@ -4257,18 +4398,44 @@ where
                let mut random_bytes = [0u8; 16];
                random_bytes.copy_from_slice(&self.entropy_source.get_secure_random_bytes()[..16]);
                let user_channel_id = u128::from_be_bytes(random_bytes);
-
                let outbound_scid_alias = self.create_and_insert_outbound_scid_alias();
+
+               // 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 per_peer_state = self.per_peer_state.read().unwrap();
-               let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id);
-               if let None = peer_state_mutex_opt {
-                       return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.temporary_channel_id.clone()))
-               }
-               let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
+               let peer_state_mutex = per_peer_state.get(counterparty_node_id)
+                   .ok_or_else(|| {
+                               debug_assert!(false);
+                               MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.temporary_channel_id.clone())
+                       })?;
+               let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
+
+               // 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() &&
+                       channeled_peers_without_funding >= MAX_UNFUNDED_CHANNEL_PEERS &&
+                       !self.default_configuration.manually_accept_inbound_channels
+               {
+                       return Err(MsgHandleErrInternal::send_err_msg_no_close(
+                               "Have too many peers with unfunded channels, not accepting new ones".to_owned(),
+                               msg.temporary_channel_id.clone()));
+               }
+
+               let best_block_height = self.best_block.read().unwrap().height();
+               if Self::unfunded_channel_count(peer_state, best_block_height) >= MAX_UNFUNDED_CHANS_PER_PEER {
+                       return Err(MsgHandleErrInternal::send_err_msg_no_close(
+                               format!("Refusing more than {} unfunded channels.", MAX_UNFUNDED_CHANS_PER_PEER),
+                               msg.temporary_channel_id.clone()));
+               }
+
                let mut channel = match Channel::new_from_req(&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,
-                       self.best_block.read().unwrap().height(), &self.logger, outbound_scid_alias)
+                       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)
                {
                        Err(e) => {
                                self.outbound_scid_aliases.lock().unwrap().remove(&outbound_scid_alias);
@@ -4312,11 +4479,12 @@ where
        fn internal_accept_channel(&self, counterparty_node_id: &PublicKey, msg: &msgs::AcceptChannel) -> Result<(), MsgHandleErrInternal> {
                let (value, output_script, user_id) = {
                        let per_peer_state = self.per_peer_state.read().unwrap();
-                       let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id);
-                       if let None = peer_state_mutex_opt {
-                               return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.temporary_channel_id))
-                       }
-                       let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
+                       let peer_state_mutex = per_peer_state.get(counterparty_node_id)
+                               .ok_or_else(|| {
+                                       debug_assert!(false);
+                                       MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.temporary_channel_id)
+                               })?;
+                       let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        match peer_state.channel_by_id.entry(msg.temporary_channel_id) {
                                hash_map::Entry::Occupied(mut chan) => {
@@ -4339,13 +4507,14 @@ where
 
        fn internal_funding_created(&self, counterparty_node_id: &PublicKey, msg: &msgs::FundingCreated) -> Result<(), MsgHandleErrInternal> {
                let per_peer_state = self.per_peer_state.read().unwrap();
-               let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id);
-               if let None = peer_state_mutex_opt {
-                       return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.temporary_channel_id))
-               }
+               let peer_state_mutex = per_peer_state.get(counterparty_node_id)
+                       .ok_or_else(|| {
+                               debug_assert!(false);
+                               MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.temporary_channel_id)
+                       })?;
                let ((funding_msg, monitor, mut channel_ready), mut chan) = {
                        let best_block = *self.best_block.read().unwrap();
-                       let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
+                       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) {
                                hash_map::Entry::Occupied(mut chan) => {
@@ -4382,7 +4551,7 @@ where
                // It's safe to unwrap as we've held the `per_peer_state` read lock since checking that the
                // peer exists, despite the inner PeerState potentially having no channels after removing
                // the channel above.
-               let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
+               let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                match peer_state.channel_by_id.entry(funding_msg.channel_id) {
                        hash_map::Entry::Occupied(_) => {
@@ -4417,12 +4586,13 @@ where
                let funding_tx = {
                        let best_block = *self.best_block.read().unwrap();
                        let per_peer_state = self.per_peer_state.read().unwrap();
-                       let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id);
-                       if let None = peer_state_mutex_opt {
-                               return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id))
-                       }
+                       let peer_state_mutex = per_peer_state.get(counterparty_node_id)
+                               .ok_or_else(|| {
+                                       debug_assert!(false);
+                                       MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
+                               })?;
 
-                       let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
+                       let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        match peer_state.channel_by_id.entry(msg.channel_id) {
                                hash_map::Entry::Occupied(mut chan) => {
@@ -4460,11 +4630,12 @@ where
 
        fn internal_channel_ready(&self, counterparty_node_id: &PublicKey, msg: &msgs::ChannelReady) -> Result<(), MsgHandleErrInternal> {
                let per_peer_state = self.per_peer_state.read().unwrap();
-               let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id);
-               if let None = peer_state_mutex_opt {
-                       return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id));
-               }
-               let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
+               let peer_state_mutex = per_peer_state.get(counterparty_node_id)
+                       .ok_or_else(|| {
+                               debug_assert!(false);
+                               MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
+                       })?;
+               let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                match peer_state.channel_by_id.entry(msg.channel_id) {
                        hash_map::Entry::Occupied(mut chan) => {
@@ -4503,11 +4674,12 @@ where
                let mut dropped_htlcs: Vec<(HTLCSource, PaymentHash)>;
                let result: Result<(), _> = loop {
                        let per_peer_state = self.per_peer_state.read().unwrap();
-                       let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id);
-                       if let None = peer_state_mutex_opt {
-                               return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id))
-                       }
-                       let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
+                       let peer_state_mutex = per_peer_state.get(counterparty_node_id)
+                               .ok_or_else(|| {
+                                       debug_assert!(false);
+                                       MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
+                               })?;
+                       let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        match peer_state.channel_by_id.entry(msg.channel_id.clone()) {
                                hash_map::Entry::Occupied(mut chan_entry) => {
@@ -4556,12 +4728,13 @@ where
 
        fn internal_closing_signed(&self, counterparty_node_id: &PublicKey, msg: &msgs::ClosingSigned) -> Result<(), MsgHandleErrInternal> {
                let per_peer_state = self.per_peer_state.read().unwrap();
-               let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id);
-               if let None = peer_state_mutex_opt {
-                       return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id))
-               }
+               let peer_state_mutex = per_peer_state.get(counterparty_node_id)
+                       .ok_or_else(|| {
+                               debug_assert!(false);
+                               MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
+                       })?;
                let (tx, chan_option) = {
-                       let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
+                       let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        match peer_state.channel_by_id.entry(msg.channel_id.clone()) {
                                hash_map::Entry::Occupied(mut chan_entry) => {
@@ -4590,7 +4763,7 @@ where
                }
                if let Some(chan) = chan_option {
                        if let Ok(update) = self.get_channel_update_for_broadcast(&chan) {
-                               let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
+                               let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                                let peer_state = &mut *peer_state_lock;
                                peer_state.pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
                                        msg: update
@@ -4613,11 +4786,12 @@ where
 
                let pending_forward_info = self.decode_update_add_htlc_onion(msg);
                let per_peer_state = self.per_peer_state.read().unwrap();
-               let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id);
-               if let None = peer_state_mutex_opt {
-                       return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id))
-               }
-               let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
+               let peer_state_mutex = per_peer_state.get(counterparty_node_id)
+                       .ok_or_else(|| {
+                               debug_assert!(false);
+                               MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
+                       })?;
+               let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                match peer_state.channel_by_id.entry(msg.channel_id) {
                        hash_map::Entry::Occupied(mut chan) => {
@@ -4654,11 +4828,12 @@ where
        fn internal_update_fulfill_htlc(&self, counterparty_node_id: &PublicKey, msg: &msgs::UpdateFulfillHTLC) -> Result<(), MsgHandleErrInternal> {
                let (htlc_source, forwarded_htlc_value) = {
                        let per_peer_state = self.per_peer_state.read().unwrap();
-                       let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id);
-                       if let None = peer_state_mutex_opt {
-                               return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id));
-                       }
-                       let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
+                       let peer_state_mutex = per_peer_state.get(counterparty_node_id)
+                               .ok_or_else(|| {
+                                       debug_assert!(false);
+                                       MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
+                               })?;
+                       let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        match peer_state.channel_by_id.entry(msg.channel_id) {
                                hash_map::Entry::Occupied(mut chan) => {
@@ -4673,11 +4848,12 @@ where
 
        fn internal_update_fail_htlc(&self, counterparty_node_id: &PublicKey, msg: &msgs::UpdateFailHTLC) -> Result<(), MsgHandleErrInternal> {
                let per_peer_state = self.per_peer_state.read().unwrap();
-               let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id);
-               if let None = peer_state_mutex_opt {
-                       return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id));
-               }
-               let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
+               let peer_state_mutex = per_peer_state.get(counterparty_node_id)
+                       .ok_or_else(|| {
+                               debug_assert!(false);
+                               MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
+                       })?;
+               let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                match peer_state.channel_by_id.entry(msg.channel_id) {
                        hash_map::Entry::Occupied(mut chan) => {
@@ -4690,11 +4866,12 @@ where
 
        fn internal_update_fail_malformed_htlc(&self, counterparty_node_id: &PublicKey, msg: &msgs::UpdateFailMalformedHTLC) -> Result<(), MsgHandleErrInternal> {
                let per_peer_state = self.per_peer_state.read().unwrap();
-               let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id);
-               if let None = peer_state_mutex_opt {
-                       return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id))
-               }
-               let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
+               let peer_state_mutex = per_peer_state.get(counterparty_node_id)
+                       .ok_or_else(|| {
+                               debug_assert!(false);
+                               MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
+                       })?;
+               let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                match peer_state.channel_by_id.entry(msg.channel_id) {
                        hash_map::Entry::Occupied(mut chan) => {
@@ -4711,11 +4888,12 @@ where
 
        fn internal_commitment_signed(&self, counterparty_node_id: &PublicKey, msg: &msgs::CommitmentSigned) -> Result<(), MsgHandleErrInternal> {
                let per_peer_state = self.per_peer_state.read().unwrap();
-               let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id);
-               if let None = peer_state_mutex_opt {
-                       return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id))
-               }
-               let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
+               let peer_state_mutex = per_peer_state.get(counterparty_node_id)
+                       .ok_or_else(|| {
+                               debug_assert!(false);
+                               MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
+                       })?;
+               let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                match peer_state.channel_by_id.entry(msg.channel_id) {
                        hash_map::Entry::Occupied(mut chan) => {
@@ -4761,7 +4939,7 @@ where
        #[inline]
        fn forward_htlcs(&self, per_source_pending_forwards: &mut [(u64, OutPoint, u128, Vec<(PendingHTLCInfo, u64)>)]) {
                for &mut (prev_short_channel_id, prev_funding_outpoint, prev_user_channel_id, ref mut pending_forwards) in per_source_pending_forwards {
-                       let mut forward_event = None;
+                       let mut push_forward_event = false;
                        let mut new_intercept_events = Vec::new();
                        let mut failed_intercept_forwards = Vec::new();
                        if !pending_forwards.is_empty() {
@@ -4819,7 +4997,7 @@ where
                                                                // We don't want to generate a PendingHTLCsForwardable event if only intercepted
                                                                // payments are being processed.
                                                                if forward_htlcs_empty {
-                                                                       forward_event = Some(Duration::from_millis(MIN_HTLC_RELAY_HOLDING_CELL_MILLIS));
+                                                                       push_forward_event = true;
                                                                }
                                                                entry.insert(vec!(HTLCForwardInfo::AddHTLC(PendingAddHTLCInfo {
                                                                        prev_short_channel_id, prev_funding_outpoint, prev_htlc_id, prev_user_channel_id, forward_info })));
@@ -4837,16 +5015,21 @@ where
                                let mut events = self.pending_events.lock().unwrap();
                                events.append(&mut new_intercept_events);
                        }
+                       if push_forward_event { self.push_pending_forwards_ev() }
+               }
+       }
 
-                       match forward_event {
-                               Some(time) => {
-                                       let mut pending_events = self.pending_events.lock().unwrap();
-                                       pending_events.push(events::Event::PendingHTLCsForwardable {
-                                               time_forwardable: time
-                                       });
-                               }
-                               None => {},
-                       }
+       // We only want to push a PendingHTLCsForwardable event if no others are queued.
+       fn push_pending_forwards_ev(&self) {
+               let mut pending_events = self.pending_events.lock().unwrap();
+               let forward_ev_exists = pending_events.iter()
+                       .find(|ev| if let events::Event::PendingHTLCsForwardable { .. } = ev { true } else { false })
+                       .is_some();
+               if !forward_ev_exists {
+                       pending_events.push(events::Event::PendingHTLCsForwardable {
+                               time_forwardable:
+                                       Duration::from_millis(MIN_HTLC_RELAY_HOLDING_CELL_MILLIS),
+                       });
                }
        }
 
@@ -4854,11 +5037,12 @@ where
                let mut htlcs_to_fail = Vec::new();
                let res = loop {
                        let per_peer_state = self.per_peer_state.read().unwrap();
-                       let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id);
-                       if let None = peer_state_mutex_opt {
-                               break Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id))
-                       }
-                       let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
+                       let peer_state_mutex = per_peer_state.get(counterparty_node_id)
+                               .ok_or_else(|| {
+                                       debug_assert!(false);
+                                       MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
+                               })?;
+                       let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        match peer_state.channel_by_id.entry(msg.channel_id) {
                                hash_map::Entry::Occupied(mut chan) => {
@@ -4919,11 +5103,12 @@ where
 
        fn internal_update_fee(&self, counterparty_node_id: &PublicKey, msg: &msgs::UpdateFee) -> Result<(), MsgHandleErrInternal> {
                let per_peer_state = self.per_peer_state.read().unwrap();
-               let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id);
-               if let None = peer_state_mutex_opt {
-                       return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id));
-               }
-               let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
+               let peer_state_mutex = per_peer_state.get(counterparty_node_id)
+                       .ok_or_else(|| {
+                               debug_assert!(false);
+                               MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
+                       })?;
+               let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                match peer_state.channel_by_id.entry(msg.channel_id) {
                        hash_map::Entry::Occupied(mut chan) => {
@@ -4936,11 +5121,12 @@ where
 
        fn internal_announcement_signatures(&self, counterparty_node_id: &PublicKey, msg: &msgs::AnnouncementSignatures) -> Result<(), MsgHandleErrInternal> {
                let per_peer_state = self.per_peer_state.read().unwrap();
-               let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id);
-               if let None = peer_state_mutex_opt {
-                       return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id));
-               }
-               let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
+               let peer_state_mutex = per_peer_state.get(counterparty_node_id)
+                       .ok_or_else(|| {
+                               debug_assert!(false);
+                               MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
+                       })?;
+               let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                let peer_state = &mut *peer_state_lock;
                match peer_state.channel_by_id.entry(msg.channel_id) {
                        hash_map::Entry::Occupied(mut chan) => {
@@ -4955,7 +5141,7 @@ where
                                        ), chan),
                                        // Note that announcement_signatures fails if the channel cannot be announced,
                                        // so get_channel_update_for_broadcast will never fail by the time we get here.
-                                       update_msg: self.get_channel_update_for_broadcast(chan.get()).unwrap(),
+                                       update_msg: Some(self.get_channel_update_for_broadcast(chan.get()).unwrap()),
                                });
                        },
                        hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Got a message for a channel from the wrong node! No such channel for the passed counterparty_node_id {}", counterparty_node_id), msg.channel_id))
@@ -4974,7 +5160,7 @@ where
                };
                let per_peer_state = self.per_peer_state.read().unwrap();
                let peer_state_mutex_opt = per_peer_state.get(&chan_counterparty_node_id);
-               if let None = peer_state_mutex_opt {
+               if peer_state_mutex_opt.is_none() {
                        return Ok(NotifyOption::SkipPersist)
                }
                let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
@@ -5009,11 +5195,12 @@ where
                let need_lnd_workaround = {
                        let per_peer_state = self.per_peer_state.read().unwrap();
 
-                       let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id);
-                       if let None = peer_state_mutex_opt {
-                               return Err(MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id));
-                       }
-                       let mut peer_state_lock = peer_state_mutex_opt.unwrap().lock().unwrap();
+                       let peer_state_mutex = per_peer_state.get(counterparty_node_id)
+                               .ok_or_else(|| {
+                                       debug_assert!(false);
+                                       MsgHandleErrInternal::send_err_msg_no_close(format!("Can't find a peer matching the passed counterparty node_id {}", counterparty_node_id), msg.channel_id)
+                               })?;
+                       let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        match peer_state.channel_by_id.entry(msg.channel_id) {
                                hash_map::Entry::Occupied(mut chan) => {
@@ -5329,7 +5516,8 @@ where
        /// [`PaymentHash`] and [`PaymentPreimage`] for you.
        ///
        /// The [`PaymentPreimage`] will ultimately be returned to you in the [`PaymentClaimable`], which
-       /// will have the [`PaymentClaimable::payment_preimage`] field filled in. That should then be
+       /// will have the [`PaymentClaimable::purpose`] be [`PaymentPurpose::InvoicePayment`] with
+       /// its [`PaymentPurpose::InvoicePayment::payment_preimage`] field filled in. That should then be
        /// passed directly to [`claim_funds`].
        ///
        /// See [`create_inbound_payment_for_hash`] for detailed documentation on behavior and requirements.
@@ -5349,7 +5537,9 @@ where
        ///
        /// [`claim_funds`]: Self::claim_funds
        /// [`PaymentClaimable`]: events::Event::PaymentClaimable
-       /// [`PaymentClaimable::payment_preimage`]: events::Event::PaymentClaimable::payment_preimage
+       /// [`PaymentClaimable::purpose`]: events::Event::PaymentClaimable::purpose
+       /// [`PaymentPurpose::InvoicePayment`]: events::PaymentPurpose::InvoicePayment
+       /// [`PaymentPurpose::InvoicePayment::payment_preimage`]: events::PaymentPurpose::InvoicePayment::payment_preimage
        /// [`create_inbound_payment_for_hash`]: Self::create_inbound_payment_for_hash
        pub fn create_inbound_payment(&self, min_value_msat: Option<u64>, invoice_expiry_delta_secs: u32,
                min_final_cltv_expiry_delta: Option<u16>) -> Result<(PaymentHash, PaymentSecret), ()> {
@@ -5524,6 +5714,12 @@ where
                events.into_inner()
        }
 
+       #[cfg(feature = "_test_utils")]
+       pub fn push_pending_event(&self, event: events::Event) {
+               let mut events = self.pending_events.lock().unwrap();
+               events.push(event);
+       }
+
        #[cfg(test)]
        pub fn pop_pending_event(&self) -> Option<events::Event> {
                let mut events = self.pending_events.lock().unwrap();
@@ -5622,9 +5818,7 @@ where
                                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                                let peer_state = &mut *peer_state_lock;
                                if peer_state.pending_msg_events.len() > 0 {
-                                       let mut peer_pending_events = Vec::new();
-                                       mem::swap(&mut peer_pending_events, &mut peer_state.pending_msg_events);
-                                       pending_events.append(&mut peer_pending_events);
+                                       pending_events.append(&mut peer_state.pending_msg_events);
                                }
                        }
 
@@ -5790,8 +5984,8 @@ where
                        let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                        let peer_state = &mut *peer_state_lock;
                        for chan in peer_state.channel_by_id.values() {
-                               if let (Some(funding_txo), block_hash) = (chan.get_funding_txo(), chan.get_funding_tx_confirmed_in()) {
-                                       res.push((funding_txo.txid, block_hash));
+                               if let (Some(funding_txo), Some(block_hash)) = (chan.get_funding_txo(), chan.get_funding_tx_confirmed_in()) {
+                                       res.push((funding_txo.txid, Some(block_hash)));
                                }
                        }
                }
@@ -5875,7 +6069,7 @@ where
                                                                                msg: announcement,
                                                                                // Note that announcement_signatures fails if the channel cannot be announced,
                                                                                // so get_channel_update_for_broadcast will never fail by the time we get here.
-                                                                               update_msg: self.get_channel_update_for_broadcast(channel).unwrap(),
+                                                                               update_msg: Some(self.get_channel_update_for_broadcast(channel).unwrap()),
                                                                        });
                                                                }
                                                        }
@@ -6152,14 +6346,13 @@ where
                let _ = handle_error!(self, self.internal_channel_reestablish(counterparty_node_id, msg), *counterparty_node_id);
        }
 
-       fn peer_disconnected(&self, counterparty_node_id: &PublicKey, no_connection_possible: bool) {
+       fn peer_disconnected(&self, counterparty_node_id: &PublicKey) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);
                let mut failed_channels = Vec::new();
-               let mut no_channels_remain = true;
                let mut per_peer_state = self.per_peer_state.write().unwrap();
-               {
-                       log_debug!(self.logger, "Marking channels with {} disconnected and generating channel_updates. We believe we {} make future connections to this peer.",
-                               log_pubkey!(counterparty_node_id), if no_connection_possible { "cannot" } else { "can" });
+               let remove_peer = {
+                       log_debug!(self.logger, "Marking channels with {} disconnected and generating channel_updates.",
+                               log_pubkey!(counterparty_node_id));
                        if let Some(peer_state_mutex) = per_peer_state.get(counterparty_node_id) {
                                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                                let peer_state = &mut *peer_state_lock;
@@ -6170,8 +6363,6 @@ where
                                                update_maps_on_chan_removal!(self, chan);
                                                self.issue_channel_close_events(chan, ClosureReason::DisconnectedPeer);
                                                return false;
-                                       } else {
-                                               no_channels_remain = false;
                                        }
                                        true
                                });
@@ -6191,6 +6382,7 @@ where
                                                &events::MessageSendEvent::SendChannelAnnouncement { .. } => false,
                                                &events::MessageSendEvent::BroadcastChannelAnnouncement { .. } => true,
                                                &events::MessageSendEvent::BroadcastChannelUpdate { .. } => true,
+                                               &events::MessageSendEvent::BroadcastNodeAnnouncement { .. } => true,
                                                &events::MessageSendEvent::SendChannelUpdate { .. } => false,
                                                &events::MessageSendEvent::HandleError { .. } => false,
                                                &events::MessageSendEvent::SendChannelRangeQuery { .. } => false,
@@ -6199,9 +6391,12 @@ where
                                                &events::MessageSendEvent::SendGossipTimestampFilter { .. } => false,
                                        }
                                });
-                       }
-               }
-               if no_channels_remain {
+                               debug_assert!(peer_state.is_connected, "A disconnected peer cannot disconnect");
+                               peer_state.is_connected = false;
+                               peer_state.ok_to_remove(true)
+                       } else { debug_assert!(false, "Unconnected peer disconnected"); true }
+               };
+               if remove_peer {
                        per_peer_state.remove(counterparty_node_id);
                }
                mem::drop(per_peer_state);
@@ -6211,34 +6406,56 @@ where
                }
        }
 
-       fn peer_connected(&self, counterparty_node_id: &PublicKey, init_msg: &msgs::Init) -> Result<(), ()> {
+       fn peer_connected(&self, counterparty_node_id: &PublicKey, init_msg: &msgs::Init, inbound: bool) -> Result<(), ()> {
                if !init_msg.features.supports_static_remote_key() {
-                       log_debug!(self.logger, "Peer {} does not support static remote key, disconnecting with no_connection_possible", log_pubkey!(counterparty_node_id));
+                       log_debug!(self.logger, "Peer {} does not support static remote key, disconnecting", log_pubkey!(counterparty_node_id));
                        return Err(());
                }
 
-               log_debug!(self.logger, "Generating channel_reestablish events for {}", log_pubkey!(counterparty_node_id));
-
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);
 
+               // If we have too many peers connected which don't have funded channels, disconnect the
+               // peer immediately (as long as it doesn't have funded channels). If we have a bunch of
+               // unfunded channels taking up space in memory for disconnected peers, we still let new
+               // peers connect, but we'll reject new channels from them.
+               let connected_peers_without_funded_channels = self.peers_without_funded_channels(|node| node.is_connected);
+               let inbound_peer_limited = inbound && connected_peers_without_funded_channels >= MAX_NO_CHANNEL_PEERS;
+
                {
                        let mut peer_state_lock = self.per_peer_state.write().unwrap();
                        match peer_state_lock.entry(counterparty_node_id.clone()) {
                                hash_map::Entry::Vacant(e) => {
+                                       if inbound_peer_limited {
+                                               return Err(());
+                                       }
                                        e.insert(Mutex::new(PeerState {
                                                channel_by_id: HashMap::new(),
                                                latest_features: init_msg.features.clone(),
                                                pending_msg_events: Vec::new(),
+                                               is_connected: true,
                                        }));
                                },
                                hash_map::Entry::Occupied(e) => {
-                                       e.get().lock().unwrap().latest_features = init_msg.features.clone();
+                                       let mut peer_state = e.get().lock().unwrap();
+                                       peer_state.latest_features = init_msg.features.clone();
+
+                                       let best_block_height = self.best_block.read().unwrap().height();
+                                       if inbound_peer_limited &&
+                                               Self::unfunded_channel_count(&*peer_state, best_block_height) ==
+                                               peer_state.channel_by_id.len()
+                                       {
+                                               return Err(());
+                                       }
+
+                                       debug_assert!(!peer_state.is_connected, "A peer shouldn't be connected twice");
+                                       peer_state.is_connected = true;
                                },
                        }
                }
 
-               let per_peer_state = self.per_peer_state.read().unwrap();
+               log_debug!(self.logger, "Generating channel_reestablish events for {}", log_pubkey!(counterparty_node_id));
 
+               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;
@@ -6283,7 +6500,7 @@ where
                        let channel_ids: Vec<[u8; 32]> = {
                                let per_peer_state = self.per_peer_state.read().unwrap();
                                let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id);
-                               if let None = peer_state_mutex_opt { return; }
+                               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()
@@ -6297,7 +6514,7 @@ where
                                // First check if we can advance the channel type and try again.
                                let per_peer_state = self.per_peer_state.read().unwrap();
                                let peer_state_mutex_opt = per_peer_state.get(counterparty_node_id);
-                               if let None = peer_state_mutex_opt { return; }
+                               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) {
@@ -6791,6 +7008,7 @@ where
                        best_block.block_hash().write(writer)?;
                }
 
+               let mut serializable_peer_count: u64 = 0;
                {
                        let per_peer_state = self.per_peer_state.read().unwrap();
                        let mut unfunded_channels = 0;
@@ -6798,6 +7016,9 @@ where
                        for (_, peer_state_mutex) in per_peer_state.iter() {
                                let mut peer_state_lock = peer_state_mutex.lock().unwrap();
                                let peer_state = &mut *peer_state_lock;
+                               if !peer_state.ok_to_remove(false) {
+                                       serializable_peer_count += 1;
+                               }
                                number_of_channels += peer_state.channel_by_id.len();
                                for (_, channel) in peer_state.channel_by_id.iter() {
                                        if !channel.is_funding_initiated() {
@@ -6848,11 +7069,18 @@ where
                        htlc_purposes.push(purpose);
                }
 
-               (per_peer_state.len() as u64).write(writer)?;
+               (serializable_peer_count).write(writer)?;
                for (peer_pubkey, peer_state_mutex) in per_peer_state.iter() {
-                       peer_pubkey.write(writer)?;
-                       let peer_state = peer_state_mutex.lock().unwrap();
-                       peer_state.latest_features.write(writer)?;
+                       let peer_state_lock = peer_state_mutex.lock().unwrap();
+                       let peer_state = &*peer_state_lock;
+                       // Peers which we have no channels to should be dropped once disconnected. As we
+                       // disconnect all peers when shutting down and serializing the ChannelManager, we
+                       // consider all peers as disconnected here. There's therefore no need write peers with
+                       // no channels.
+                       if !peer_state.ok_to_remove(false) {
+                               peer_pubkey.write(writer)?;
+                               peer_state.latest_features.write(writer)?;
+                       }
                }
 
                let events = self.pending_events.lock().unwrap();
@@ -7251,6 +7479,7 @@ where
                                channel_by_id: peer_channels.remove(&peer_pubkey).unwrap_or(HashMap::new()),
                                latest_features: Readable::read(reader)?,
                                pending_msg_events: Vec::new(),
+                               is_connected: false,
                        };
                        per_peer_state.insert(peer_pubkey, Mutex::new(peer_state));
                }
@@ -7361,12 +7590,13 @@ where
                                                                hash_map::Entry::Vacant(entry) => {
                                                                        let path_fee = path.get_path_fees();
                                                                        entry.insert(PendingOutboundPayment::Retryable {
-                                                                               retry_strategy: Retry::Attempts(0),
+                                                                               retry_strategy: None,
                                                                                attempts: PaymentAttempts::new(),
-                                                                               route_params: None,
+                                                                               payment_params: None,
                                                                                session_privs: [session_priv_bytes].iter().map(|a| *a).collect(),
                                                                                payment_hash: htlc.payment_hash,
                                                                                payment_secret,
+                                                                               keysend_preimage: None, // only used for retries, and we'll never retry on startup
                                                                                pending_amt_msat: path_amt,
                                                                                pending_fee_msat: Some(path_fee),
                                                                                total_msat: path_amt,
@@ -7419,7 +7649,8 @@ where
                        }
                }
 
-               if !forward_htlcs.is_empty() {
+               let pending_outbounds = OutboundPayments { pending_outbound_payments: Mutex::new(pending_outbound_payments.unwrap()), retry_lock: Mutex::new(()) };
+               if !forward_htlcs.is_empty() || pending_outbounds.needs_abandon() {
                        // If we have pending HTLCs to forward, assume we either dropped a
                        // `PendingHTLCsForwardable` or the user received it but never processed it as they
                        // shut down before the timer hit. Either way, set the time_forwardable to a small
@@ -7587,7 +7818,7 @@ where
 
                        inbound_payment_key: expanded_inbound_key,
                        pending_inbound_payments: Mutex::new(pending_inbound_payments),
-                       pending_outbound_payments: OutboundPayments { pending_outbound_payments: Mutex::new(pending_outbound_payments.unwrap()) },
+                       pending_outbound_payments: pending_outbounds,
                        pending_intercepted_htlcs: Mutex::new(pending_intercepted_htlcs.unwrap()),
 
                        forward_htlcs: Mutex::new(forward_htlcs),
@@ -7637,19 +7868,14 @@ where
 mod tests {
        use bitcoin::hashes::Hash;
        use bitcoin::hashes::sha256::Hash as Sha256;
-       use bitcoin::hashes::hex::FromHex;
        use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
-       use bitcoin::secp256k1::ecdsa::Signature;
-       use bitcoin::secp256k1::ffi::Signature as FFISignature;
-       use bitcoin::blockdata::script::Script;
-       use bitcoin::Txid;
        use core::time::Duration;
        use core::sync::atomic::Ordering;
        use crate::ln::{PaymentPreimage, PaymentHash, PaymentSecret};
        use crate::ln::channelmanager::{inbound_payment, PaymentId, PaymentSendFailure, InterceptId};
        use crate::ln::functional_test_utils::*;
        use crate::ln::msgs;
-       use crate::ln::msgs::{ChannelMessageHandler, OptionalField};
+       use crate::ln::msgs::ChannelMessageHandler;
        use crate::routing::router::{PaymentParameters, RouteParameters, find_route};
        use crate::util::errors::APIError;
        use crate::util::events::{Event, HTLCDestination, MessageSendEvent, MessageSendEventsProvider, ClosureReason};
@@ -7866,7 +8092,7 @@ mod tests {
                let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
                let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
                create_announced_chan_between_nodes(&nodes, 0, 1);
-               let scorer = test_utils::TestScorer::with_penalty(0);
+               let scorer = test_utils::TestScorer::new();
                let random_seed_bytes = chanmon_cfgs[1].keys_manager.get_secure_random_bytes();
 
                // To start (1), send a regular payment but don't claim it.
@@ -7963,8 +8189,6 @@ mod tests {
 
                let payer_pubkey = nodes[0].node.get_our_node_id();
                let payee_pubkey = nodes[1].node.get_our_node_id();
-               nodes[0].node.peer_connected(&payee_pubkey, &msgs::Init { features: nodes[1].node.init_features(), remote_network_address: None }).unwrap();
-               nodes[1].node.peer_connected(&payer_pubkey, &msgs::Init { features: nodes[0].node.init_features(), remote_network_address: None }).unwrap();
 
                let _chan = create_chan_between_nodes(&nodes[0], &nodes[1]);
                let route_params = RouteParameters {
@@ -7974,7 +8198,7 @@ mod tests {
                };
                let network_graph = nodes[0].network_graph.clone();
                let first_hops = nodes[0].node.list_usable_channels();
-               let scorer = test_utils::TestScorer::with_penalty(0);
+               let scorer = test_utils::TestScorer::new();
                let random_seed_bytes = chanmon_cfgs[1].keys_manager.get_secure_random_bytes();
                let route = find_route(
                        &payer_pubkey, &route_params, &network_graph, Some(&first_hops.iter().collect::<Vec<_>>()),
@@ -8008,8 +8232,6 @@ mod tests {
 
                let payer_pubkey = nodes[0].node.get_our_node_id();
                let payee_pubkey = nodes[1].node.get_our_node_id();
-               nodes[0].node.peer_connected(&payee_pubkey, &msgs::Init { features: nodes[1].node.init_features(), remote_network_address: None }).unwrap();
-               nodes[1].node.peer_connected(&payer_pubkey, &msgs::Init { features: nodes[0].node.init_features(), remote_network_address: None }).unwrap();
 
                let _chan = create_chan_between_nodes(&nodes[0], &nodes[1]);
                let route_params = RouteParameters {
@@ -8019,7 +8241,7 @@ mod tests {
                };
                let network_graph = nodes[0].network_graph.clone();
                let first_hops = nodes[0].node.list_usable_channels();
-               let scorer = test_utils::TestScorer::with_penalty(0);
+               let scorer = test_utils::TestScorer::new();
                let random_seed_bytes = chanmon_cfgs[1].keys_manager.get_secure_random_bytes();
                let route = find_route(
                        &payer_pubkey, &route_params, &network_graph, Some(&first_hops.iter().collect::<Vec<_>>()),
@@ -8074,6 +8296,40 @@ mod tests {
                }
        }
 
+       #[test]
+       fn test_drop_disconnected_peers_when_removing_channels() {
+               let chanmon_cfgs = create_chanmon_cfgs(2);
+               let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
+               let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
+               let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
+
+               let chan = create_announced_chan_between_nodes(&nodes, 0, 1);
+
+               nodes[0].node.peer_disconnected(&nodes[1].node.get_our_node_id());
+               nodes[1].node.peer_disconnected(&nodes[0].node.get_our_node_id());
+
+               nodes[0].node.force_close_broadcasting_latest_txn(&chan.2, &nodes[1].node.get_our_node_id()).unwrap();
+               check_closed_broadcast!(nodes[0], true);
+               check_added_monitors!(nodes[0], 1);
+               check_closed_event!(nodes[0], 1, ClosureReason::HolderForceClosed);
+
+               {
+                       // Assert that nodes[1] is awaiting removal for nodes[0] once nodes[1] has been
+                       // disconnected and the channel between has been force closed.
+                       let nodes_0_per_peer_state = nodes[0].node.per_peer_state.read().unwrap();
+                       // Assert that nodes[1] isn't removed before `timer_tick_occurred` has been executed.
+                       assert_eq!(nodes_0_per_peer_state.len(), 1);
+                       assert!(nodes_0_per_peer_state.get(&nodes[1].node.get_our_node_id()).is_some());
+               }
+
+               nodes[0].node.timer_tick_occurred();
+
+               {
+                       // Assert that nodes[1] has now been removed.
+                       assert_eq!(nodes[0].node.per_peer_state.read().unwrap().len(), 0);
+               }
+       }
+
        #[test]
        fn bad_inbound_payment_hash() {
                // Add coverage for checking that a user-provided payment hash matches the payment secret.
@@ -8218,19 +8474,22 @@ mod tests {
 
        fn check_not_connected_to_peer_error<T>(res_err: Result<T, APIError>, expected_public_key: PublicKey) {
                let expected_message = format!("Not connected to node: {}", expected_public_key);
-               check_api_misuse_error_message(expected_message, res_err)
+               check_api_error_message(expected_message, res_err)
        }
 
        fn check_unkown_peer_error<T>(res_err: Result<T, APIError>, expected_public_key: PublicKey) {
                let expected_message = format!("Can't find a peer matching the passed counterparty node_id {}", expected_public_key);
-               check_api_misuse_error_message(expected_message, res_err)
+               check_api_error_message(expected_message, res_err)
        }
 
-       fn check_api_misuse_error_message<T>(expected_err_message: String, res_err: Result<T, APIError>) {
+       fn check_api_error_message<T>(expected_err_message: String, res_err: Result<T, APIError>) {
                match res_err {
                        Err(APIError::APIMisuseError { err }) => {
                                assert_eq!(err, expected_err_message);
                        },
+                       Err(APIError::ChannelUnavailable { err }) => {
+                               assert_eq!(err, expected_err_message);
+                       },
                        Ok(_) => panic!("Unexpected Ok"),
                        Err(_) => panic!("Unexpected Error"),
                }
@@ -8238,170 +8497,240 @@ mod tests {
 
        #[test]
        fn test_api_calls_with_unkown_counterparty_node() {
-               // Tests that our API functions and message handlers that expects a `counterparty_node_id`
-               // as input, behaves as expected if the `counterparty_node_id` is an unkown peer in the
+               // Tests that our API functions that expects a `counterparty_node_id` as input, behaves as
+               // expected if the `counterparty_node_id` is an unkown peer in the
                // `ChannelManager::per_peer_state` map.
                let chanmon_cfg = create_chanmon_cfgs(2);
                let node_cfg = create_node_cfgs(2, &chanmon_cfg);
                let node_chanmgr = create_node_chanmgrs(2, &node_cfg, &[None, None]);
                let nodes = create_network(2, &node_cfg, &node_chanmgr);
 
-               // Boilerplate code to produce `open_channel` and `accept_channel` msgs more densly than
-               // creating dummy ones.
-               nodes[0].node.create_channel(nodes[1].node.get_our_node_id(), 1_000_000, 500_000_000, 42, None).unwrap();
-               let open_channel_msg = get_event_msg!(nodes[0], MessageSendEvent::SendOpenChannel, nodes[1].node.get_our_node_id());
-               nodes[1].node.handle_open_channel(&nodes[0].node.get_our_node_id(), &open_channel_msg);
-               let accept_channel_msg = get_event_msg!(nodes[1], MessageSendEvent::SendAcceptChannel, nodes[0].node.get_our_node_id());
-
                // Dummy values
                let channel_id = [4; 32];
-               let signature = Signature::from(unsafe { FFISignature::new() });
                let unkown_public_key = PublicKey::from_secret_key(&Secp256k1::signing_only(), &SecretKey::from_slice(&[42; 32]).unwrap());
                let intercept_id = InterceptId([0; 32]);
 
-               // Dummy msgs
-               let funding_created_msg = msgs::FundingCreated {
-                       temporary_channel_id: open_channel_msg.temporary_channel_id,
-                       funding_txid: Txid::from_hex("ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff").unwrap(),
-                       funding_output_index: 0,
-                       signature: signature,
-               };
-
-               let funding_signed_msg = msgs::FundingSigned {
-                       channel_id: channel_id,
-                       signature: signature,
-               };
-
-               let channel_ready_msg = msgs::ChannelReady {
-                       channel_id: channel_id,
-                       next_per_commitment_point: unkown_public_key,
-                       short_channel_id_alias: None,
-               };
-
-               let announcement_signatures_msg = msgs::AnnouncementSignatures {
-                       channel_id: channel_id,
-                       short_channel_id: 0,
-                       node_signature: signature,
-                       bitcoin_signature: signature,
-               };
-
-               let channel_reestablish_msg = msgs::ChannelReestablish {
-                       channel_id: channel_id,
-                       next_local_commitment_number: 0,
-                       next_remote_commitment_number: 0,
-                       data_loss_protect: OptionalField::Absent,
-               };
-
-               let closing_signed_msg = msgs::ClosingSigned {
-                       channel_id: channel_id,
-                       fee_satoshis: 1000,
-                       signature: signature,
-                       fee_range: None,
-               };
-
-               let shutdown_msg = msgs::Shutdown {
-                       channel_id: channel_id,
-                       scriptpubkey: Script::new(),
-               };
-
-               let onion_routing_packet = msgs::OnionPacket {
-                       version: 255,
-                       public_key: Ok(unkown_public_key),
-                       hop_data: [1; 20*65],
-                       hmac: [2; 32]
-               };
-
-               let update_add_htlc_msg = msgs::UpdateAddHTLC {
-                       channel_id: channel_id,
-                       htlc_id: 0,
-                       amount_msat: 1000000,
-                       payment_hash: PaymentHash([1; 32]),
-                       cltv_expiry: 821716,
-                       onion_routing_packet
-               };
-
-               let commitment_signed_msg = msgs::CommitmentSigned {
-                       channel_id: channel_id,
-                       signature: signature,
-                       htlc_signatures: Vec::new(),
-               };
+               // Test the API functions.
+               check_not_connected_to_peer_error(nodes[0].node.create_channel(unkown_public_key, 1_000_000, 500_000_000, 42, None), unkown_public_key);
 
-               let update_fee_msg = msgs::UpdateFee {
-                       channel_id: channel_id,
-                       feerate_per_kw: 1000,
-               };
+               check_unkown_peer_error(nodes[0].node.accept_inbound_channel(&channel_id, &unkown_public_key, 42), unkown_public_key);
 
-               let malformed_update_msg = msgs::UpdateFailMalformedHTLC{
-                       channel_id: channel_id,
-                       htlc_id: 0,
-                       sha256_of_onion: [1; 32],
-                       failure_code: 0x8000,
-               };
+               check_unkown_peer_error(nodes[0].node.close_channel(&channel_id, &unkown_public_key), unkown_public_key);
 
-               let fulfill_update_msg = msgs::UpdateFulfillHTLC{
-                       channel_id: channel_id,
-                       htlc_id: 0,
-                       payment_preimage: PaymentPreimage([1; 32]),
-               };
+               check_unkown_peer_error(nodes[0].node.force_close_broadcasting_latest_txn(&channel_id, &unkown_public_key), unkown_public_key);
 
-               let fail_update_msg = msgs::UpdateFailHTLC{
-                       channel_id: channel_id,
-                       htlc_id: 0,
-                       reason: msgs::OnionErrorPacket { data: Vec::new()},
-               };
+               check_unkown_peer_error(nodes[0].node.force_close_without_broadcasting_txn(&channel_id, &unkown_public_key), unkown_public_key);
 
-               let revoke_and_ack_msg = msgs::RevokeAndACK {
-                       channel_id: channel_id,
-                       per_commitment_secret: [1; 32],
-                       next_per_commitment_point: unkown_public_key,
-               };
+               check_unkown_peer_error(nodes[0].node.forward_intercepted_htlc(intercept_id, &channel_id, unkown_public_key, 1_000_000), unkown_public_key);
 
-               // Test the API functions and message handlers.
-               check_not_connected_to_peer_error(nodes[0].node.create_channel(unkown_public_key, 1_000_000, 500_000_000, 42, None), unkown_public_key);
+               check_unkown_peer_error(nodes[0].node.update_channel_config(&unkown_public_key, &[channel_id], &ChannelConfig::default()), unkown_public_key);
+       }
 
-               nodes[1].node.handle_open_channel(&unkown_public_key, &open_channel_msg);
+       #[test]
+       fn test_connection_limiting() {
+               // Test that we limit un-channel'd peers and un-funded channels properly.
+               let chanmon_cfgs = create_chanmon_cfgs(2);
+               let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
+               let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
+               let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
 
-               nodes[0].node.handle_accept_channel(&unkown_public_key, &accept_channel_msg);
+               // Note that create_network connects the nodes together for us
 
-               check_unkown_peer_error(nodes[0].node.accept_inbound_channel(&open_channel_msg.temporary_channel_id, &unkown_public_key, 42), unkown_public_key);
+               nodes[0].node.create_channel(nodes[1].node.get_our_node_id(), 100_000, 0, 42, None).unwrap();
+               let mut open_channel_msg = get_event_msg!(nodes[0], MessageSendEvent::SendOpenChannel, nodes[1].node.get_our_node_id());
 
-               nodes[1].node.handle_funding_created(&unkown_public_key, &funding_created_msg);
+               let mut funding_tx = None;
+               for idx in 0..super::MAX_UNFUNDED_CHANS_PER_PEER {
+                       nodes[1].node.handle_open_channel(&nodes[0].node.get_our_node_id(), &open_channel_msg);
+                       let accept_channel = get_event_msg!(nodes[1], MessageSendEvent::SendAcceptChannel, nodes[0].node.get_our_node_id());
 
-               nodes[0].node.handle_funding_signed(&unkown_public_key, &funding_signed_msg);
+                       if idx == 0 {
+                               nodes[0].node.handle_accept_channel(&nodes[1].node.get_our_node_id(), &accept_channel);
+                               let (temporary_channel_id, tx, _) = create_funding_transaction(&nodes[0], &nodes[1].node.get_our_node_id(), 100_000, 42);
+                               funding_tx = Some(tx.clone());
+                               nodes[0].node.funding_transaction_generated(&temporary_channel_id, &nodes[1].node.get_our_node_id(), tx).unwrap();
+                               let funding_created_msg = get_event_msg!(nodes[0], MessageSendEvent::SendFundingCreated, nodes[1].node.get_our_node_id());
 
-               nodes[0].node.handle_channel_ready(&unkown_public_key, &channel_ready_msg);
+                               nodes[1].node.handle_funding_created(&nodes[0].node.get_our_node_id(), &funding_created_msg);
+                               check_added_monitors!(nodes[1], 1);
+                               let funding_signed = get_event_msg!(nodes[1], MessageSendEvent::SendFundingSigned, nodes[0].node.get_our_node_id());
 
-               nodes[1].node.handle_announcement_signatures(&unkown_public_key, &announcement_signatures_msg);
+                               nodes[0].node.handle_funding_signed(&nodes[1].node.get_our_node_id(), &funding_signed);
+                               check_added_monitors!(nodes[0], 1);
+                       }
+                       open_channel_msg.temporary_channel_id = nodes[0].keys_manager.get_secure_random_bytes();
+               }
 
-               check_unkown_peer_error(nodes[0].node.close_channel(&channel_id, &unkown_public_key), unkown_public_key);
+               // A MAX_UNFUNDED_CHANS_PER_PEER + 1 channel will be summarily rejected
+               open_channel_msg.temporary_channel_id = nodes[0].keys_manager.get_secure_random_bytes();
+               nodes[1].node.handle_open_channel(&nodes[0].node.get_our_node_id(), &open_channel_msg);
+               assert_eq!(get_err_msg!(nodes[1], nodes[0].node.get_our_node_id()).channel_id,
+                       open_channel_msg.temporary_channel_id);
+
+               // Further, because all of our channels with nodes[0] are inbound, and none of them funded,
+               // it doesn't count as a "protected" peer, i.e. it counts towards the MAX_NO_CHANNEL_PEERS
+               // limit.
+               let mut peer_pks = Vec::with_capacity(super::MAX_NO_CHANNEL_PEERS);
+               for _ in 1..super::MAX_NO_CHANNEL_PEERS {
+                       let random_pk = PublicKey::from_secret_key(&nodes[0].node.secp_ctx,
+                               &SecretKey::from_slice(&nodes[1].keys_manager.get_secure_random_bytes()).unwrap());
+                       peer_pks.push(random_pk);
+                       nodes[1].node.peer_connected(&random_pk, &msgs::Init {
+                               features: nodes[0].node.init_features(), remote_network_address: None }, true).unwrap();
+               }
+               let last_random_pk = PublicKey::from_secret_key(&nodes[0].node.secp_ctx,
+                       &SecretKey::from_slice(&nodes[1].keys_manager.get_secure_random_bytes()).unwrap());
+               nodes[1].node.peer_connected(&last_random_pk, &msgs::Init {
+                       features: nodes[0].node.init_features(), remote_network_address: None }, true).unwrap_err();
+
+               // Also importantly, because nodes[0] isn't "protected", we will refuse a reconnection from
+               // them if we have too many un-channel'd peers.
+               nodes[1].node.peer_disconnected(&nodes[0].node.get_our_node_id());
+               let chan_closed_events = nodes[1].node.get_and_clear_pending_events();
+               assert_eq!(chan_closed_events.len(), super::MAX_UNFUNDED_CHANS_PER_PEER - 1);
+               for ev in chan_closed_events {
+                       if let Event::ChannelClosed { .. } = ev { } else { panic!(); }
+               }
+               nodes[1].node.peer_connected(&last_random_pk, &msgs::Init {
+                       features: nodes[0].node.init_features(), remote_network_address: None }, true).unwrap();
+               nodes[1].node.peer_connected(&nodes[0].node.get_our_node_id(), &msgs::Init {
+                       features: nodes[0].node.init_features(), remote_network_address: None }, true).unwrap_err();
+
+               // but of course if the connection is outbound its allowed...
+               nodes[1].node.peer_connected(&nodes[0].node.get_our_node_id(), &msgs::Init {
+                       features: nodes[0].node.init_features(), remote_network_address: None }, false).unwrap();
+               nodes[1].node.peer_disconnected(&nodes[0].node.get_our_node_id());
+
+               // Now nodes[0] is disconnected but still has a pending, un-funded channel lying around.
+               // Even though we accept one more connection from new peers, we won't actually let them
+               // open channels.
+               assert!(peer_pks.len() > super::MAX_UNFUNDED_CHANNEL_PEERS - 1);
+               for i in 0..super::MAX_UNFUNDED_CHANNEL_PEERS - 1 {
+                       nodes[1].node.handle_open_channel(&peer_pks[i], &open_channel_msg);
+                       get_event_msg!(nodes[1], MessageSendEvent::SendAcceptChannel, peer_pks[i]);
+                       open_channel_msg.temporary_channel_id = nodes[0].keys_manager.get_secure_random_bytes();
+               }
+               nodes[1].node.handle_open_channel(&last_random_pk, &open_channel_msg);
+               assert_eq!(get_err_msg!(nodes[1], last_random_pk).channel_id,
+                       open_channel_msg.temporary_channel_id);
+
+               // Of course, however, outbound channels are always allowed
+               nodes[1].node.create_channel(last_random_pk, 100_000, 0, 42, None).unwrap();
+               get_event_msg!(nodes[1], MessageSendEvent::SendOpenChannel, last_random_pk);
+
+               // If we fund the first channel, nodes[0] has a live on-chain channel with us, it is now
+               // "protected" and can connect again.
+               mine_transaction(&nodes[1], funding_tx.as_ref().unwrap());
+               nodes[1].node.peer_connected(&nodes[0].node.get_our_node_id(), &msgs::Init {
+                       features: nodes[0].node.init_features(), remote_network_address: None }, true).unwrap();
+               get_event_msg!(nodes[1], MessageSendEvent::SendChannelReestablish, nodes[0].node.get_our_node_id());
+
+               // Further, because the first channel was funded, we can open another channel with
+               // last_random_pk.
+               nodes[1].node.handle_open_channel(&last_random_pk, &open_channel_msg);
+               get_event_msg!(nodes[1], MessageSendEvent::SendAcceptChannel, last_random_pk);
+       }
 
-               check_unkown_peer_error(nodes[0].node.force_close_broadcasting_latest_txn(&channel_id, &unkown_public_key), unkown_public_key);
+       #[test]
+       fn test_outbound_chans_unlimited() {
+               // Test that we never refuse an outbound channel even if a peer is unfuned-channel-limited
+               let chanmon_cfgs = create_chanmon_cfgs(2);
+               let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
+               let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
+               let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
 
-               check_unkown_peer_error(nodes[0].node.force_close_without_broadcasting_txn(&channel_id, &unkown_public_key), unkown_public_key);
+               // Note that create_network connects the nodes together for us
 
-               check_unkown_peer_error(nodes[0].node.forward_intercepted_htlc(intercept_id, &channel_id, unkown_public_key, 1_000_000), unkown_public_key);
+               nodes[0].node.create_channel(nodes[1].node.get_our_node_id(), 100_000, 0, 42, None).unwrap();
+               let mut open_channel_msg = get_event_msg!(nodes[0], MessageSendEvent::SendOpenChannel, nodes[1].node.get_our_node_id());
 
-               check_unkown_peer_error(nodes[0].node.update_channel_config(&unkown_public_key, &[channel_id], &ChannelConfig::default()), unkown_public_key);
+               for _ in 0..super::MAX_UNFUNDED_CHANS_PER_PEER {
+                       nodes[1].node.handle_open_channel(&nodes[0].node.get_our_node_id(), &open_channel_msg);
+                       get_event_msg!(nodes[1], MessageSendEvent::SendAcceptChannel, nodes[0].node.get_our_node_id());
+                       open_channel_msg.temporary_channel_id = nodes[0].keys_manager.get_secure_random_bytes();
+               }
 
-               nodes[0].node.handle_shutdown(&unkown_public_key, &shutdown_msg);
+               // Once we have MAX_UNFUNDED_CHANS_PER_PEER unfunded channels, new inbound channels will be
+               // rejected.
+               nodes[1].node.handle_open_channel(&nodes[0].node.get_our_node_id(), &open_channel_msg);
+               assert_eq!(get_err_msg!(nodes[1], nodes[0].node.get_our_node_id()).channel_id,
+                       open_channel_msg.temporary_channel_id);
 
-               nodes[1].node.handle_closing_signed(&unkown_public_key, &closing_signed_msg);
+               // but we can still open an outbound channel.
+               nodes[1].node.create_channel(nodes[0].node.get_our_node_id(), 100_000, 0, 42, None).unwrap();
+               get_event_msg!(nodes[1], MessageSendEvent::SendOpenChannel, nodes[0].node.get_our_node_id());
 
-               nodes[0].node.handle_channel_reestablish(&unkown_public_key, &channel_reestablish_msg);
+               // but even with such an outbound channel, additional inbound channels will still fail.
+               nodes[1].node.handle_open_channel(&nodes[0].node.get_our_node_id(), &open_channel_msg);
+               assert_eq!(get_err_msg!(nodes[1], nodes[0].node.get_our_node_id()).channel_id,
+                       open_channel_msg.temporary_channel_id);
+       }
 
-               nodes[1].node.handle_update_add_htlc(&unkown_public_key, &update_add_htlc_msg);
+       #[test]
+       fn test_0conf_limiting() {
+               // Tests that we properly limit inbound channels when we have the manual-channel-acceptance
+               // flag set and (sometimes) accept channels as 0conf.
+               let chanmon_cfgs = create_chanmon_cfgs(2);
+               let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
+               let mut settings = test_default_channel_config();
+               settings.manually_accept_inbound_channels = true;
+               let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, Some(settings)]);
+               let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
 
-               nodes[1].node.handle_commitment_signed(&unkown_public_key, &commitment_signed_msg);
+               // Note that create_network connects the nodes together for us
 
-               nodes[1].node.handle_update_fail_malformed_htlc(&unkown_public_key, &malformed_update_msg);
+               nodes[0].node.create_channel(nodes[1].node.get_our_node_id(), 100_000, 0, 42, None).unwrap();
+               let mut open_channel_msg = get_event_msg!(nodes[0], MessageSendEvent::SendOpenChannel, nodes[1].node.get_our_node_id());
 
-               nodes[1].node.handle_update_fail_htlc(&unkown_public_key, &fail_update_msg);
+               // First, get us up to MAX_UNFUNDED_CHANNEL_PEERS so we can test at the edge
+               for _ in 0..super::MAX_UNFUNDED_CHANNEL_PEERS - 1 {
+                       let random_pk = PublicKey::from_secret_key(&nodes[0].node.secp_ctx,
+                               &SecretKey::from_slice(&nodes[1].keys_manager.get_secure_random_bytes()).unwrap());
+                       nodes[1].node.peer_connected(&random_pk, &msgs::Init {
+                               features: nodes[0].node.init_features(), remote_network_address: None }, true).unwrap();
 
-               nodes[1].node.handle_update_fulfill_htlc(&unkown_public_key, &fulfill_update_msg);
+                       nodes[1].node.handle_open_channel(&random_pk, &open_channel_msg);
+                       let events = nodes[1].node.get_and_clear_pending_events();
+                       match events[0] {
+                               Event::OpenChannelRequest { temporary_channel_id, .. } => {
+                                       nodes[1].node.accept_inbound_channel(&temporary_channel_id, &random_pk, 23).unwrap();
+                               }
+                               _ => panic!("Unexpected event"),
+                       }
+                       get_event_msg!(nodes[1], MessageSendEvent::SendAcceptChannel, random_pk);
+                       open_channel_msg.temporary_channel_id = nodes[0].keys_manager.get_secure_random_bytes();
+               }
 
-               nodes[1].node.handle_revoke_and_ack(&unkown_public_key, &revoke_and_ack_msg);
+               // If we try to accept a channel from another peer non-0conf it will fail.
+               let last_random_pk = PublicKey::from_secret_key(&nodes[0].node.secp_ctx,
+                       &SecretKey::from_slice(&nodes[1].keys_manager.get_secure_random_bytes()).unwrap());
+               nodes[1].node.peer_connected(&last_random_pk, &msgs::Init {
+                       features: nodes[0].node.init_features(), remote_network_address: None }, true).unwrap();
+               nodes[1].node.handle_open_channel(&last_random_pk, &open_channel_msg);
+               let events = nodes[1].node.get_and_clear_pending_events();
+               match events[0] {
+                       Event::OpenChannelRequest { temporary_channel_id, .. } => {
+                               match nodes[1].node.accept_inbound_channel(&temporary_channel_id, &last_random_pk, 23) {
+                                       Err(APIError::APIMisuseError { err }) =>
+                                               assert_eq!(err, "Too many peers with unfunded channels, refusing to accept new ones"),
+                                       _ => panic!(),
+                               }
+                       }
+                       _ => panic!("Unexpected event"),
+               }
+               assert_eq!(get_err_msg!(nodes[1], last_random_pk).channel_id,
+                       open_channel_msg.temporary_channel_id);
 
-               nodes[1].node.handle_update_fee(&unkown_public_key, &update_fee_msg);
+               // ...however if we accept the same channel 0conf it should work just fine.
+               nodes[1].node.handle_open_channel(&last_random_pk, &open_channel_msg);
+               let events = nodes[1].node.get_and_clear_pending_events();
+               match events[0] {
+                       Event::OpenChannelRequest { temporary_channel_id, .. } => {
+                               nodes[1].node.accept_inbound_channel_from_trusted_peer_0conf(&temporary_channel_id, &last_random_pk, 23).unwrap();
+                       }
+                       _ => panic!("Unexpected event"),
+               }
+               get_event_msg!(nodes[1], MessageSendEvent::SendAcceptChannel, last_random_pk);
        }
 
        #[cfg(anchors)]
@@ -8489,7 +8818,8 @@ pub mod bench {
                let tx_broadcaster = test_utils::TestBroadcaster{txn_broadcasted: Mutex::new(Vec::new()), blocks: Arc::new(Mutex::new(Vec::new()))};
                let fee_estimator = test_utils::TestFeeEstimator { sat_per_kw: Mutex::new(253) };
                let logger_a = test_utils::TestLogger::with_id("node a".to_owned());
-               let router = test_utils::TestRouter::new(Arc::new(NetworkGraph::new(genesis_hash, &logger_a)));
+               let scorer = Mutex::new(test_utils::TestScorer::new());
+               let router = test_utils::TestRouter::new(Arc::new(NetworkGraph::new(genesis_hash, &logger_a)), &scorer);
 
                let mut config: UserConfig = Default::default();
                config.channel_handshake_config.minimum_depth = 1;
@@ -8513,8 +8843,8 @@ pub mod bench {
                });
                let node_b_holder = NodeHolder { node: &node_b };
 
-               node_a.peer_connected(&node_b.get_our_node_id(), &Init { features: node_b.init_features(), remote_network_address: None }).unwrap();
-               node_b.peer_connected(&node_a.get_our_node_id(), &Init { features: node_a.init_features(), remote_network_address: None }).unwrap();
+               node_a.peer_connected(&node_b.get_our_node_id(), &Init { features: node_b.init_features(), remote_network_address: None }, true).unwrap();
+               node_b.peer_connected(&node_a.get_our_node_id(), &Init { features: node_a.init_features(), remote_network_address: None }, false).unwrap();
                node_a.create_channel(node_b.get_our_node_id(), 8_000_000, 100_000_000, 42, None).unwrap();
                node_b.handle_open_channel(&node_a.get_our_node_id(), &get_event_msg!(node_a_holder, MessageSendEvent::SendOpenChannel, node_b.get_our_node_id()));
                node_a.handle_accept_channel(&node_b.get_our_node_id(), &get_event_msg!(node_b_holder, MessageSendEvent::SendAcceptChannel, node_a.get_our_node_id()));
@@ -8580,7 +8910,7 @@ pub mod bench {
                                let usable_channels = $node_a.list_usable_channels();
                                let payment_params = PaymentParameters::from_node_id($node_b.get_our_node_id(), TEST_FINAL_CLTV)
                                        .with_features($node_b.invoice_features());
-                               let scorer = test_utils::TestScorer::with_penalty(0);
+                               let scorer = test_utils::TestScorer::new();
                                let seed = [3u8; 32];
                                let keys_manager = KeysManager::new(&seed, 42, 42);
                                let random_seed_bytes = keys_manager.get_secure_random_bytes();