Support phantom payment receive in ChannelManager, with invoice util
[rust-lightning] / lightning-invoice / src / payment.rs
index e785bb39264130a4895a25fd663e1b42560fd665..82c07199f0db871c1498fb64a21e63603aec2084 100644 (file)
@@ -32,6 +32,9 @@
 //! # extern crate lightning_invoice;
 //! # extern crate secp256k1;
 //! #
+//! # #[cfg(feature = "no-std")]
+//! # extern crate core2;
+//! #
 //! # use lightning::ln::{PaymentHash, PaymentPreimage, PaymentSecret};
 //! # use lightning::ln::channelmanager::{ChannelDetails, PaymentId, PaymentSendFailure};
 //! # use lightning::ln::msgs::LightningError;
 //! # use std::cell::RefCell;
 //! # use std::ops::Deref;
 //! #
+//! # #[cfg(not(feature = "std"))]
+//! # use core2::io;
+//! # #[cfg(feature = "std")]
+//! # use std::io;
+//! #
 //! # struct FakeEventProvider {}
 //! # impl EventsProvider for FakeEventProvider {
 //! #     fn process_pending_events<H: Deref>(&self, handler: H) where H::Target: EventHandler {}
@@ -65,6 +73,7 @@
 //! #     fn retry_payment(
 //! #         &self, route: &Route, payment_id: PaymentId
 //! #     ) -> Result<(), PaymentSendFailure> { unimplemented!() }
+//! #     fn abandon_payment(&self, payment_id: PaymentId) { unimplemented!() }
 //! # }
 //! #
 //! # struct FakeRouter {}
 //! #
 //! # struct FakeScorer {}
 //! # impl Writeable for FakeScorer {
-//! #     fn write<W: Writer>(&self, w: &mut W) -> Result<(), std::io::Error> { unimplemented!(); }
+//! #     fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> { unimplemented!(); }
 //! # }
 //! # impl Score for FakeScorer {
 //! #     fn channel_penalty_msat(
-//! #         &self, _short_channel_id: u64, _send_amt: u64, _chan_amt: Option<u64>, _source: &NodeId, _target: &NodeId
+//! #         &self, _short_channel_id: u64, _send_amt: u64, _chan_amt: u64, _source: &NodeId, _target: &NodeId
 //! #     ) -> u64 { 0 }
 //! #     fn payment_path_failed(&mut self, _path: &[&RouteHop], _short_channel_id: u64) {}
 //! #     fn payment_path_successful(&mut self, _path: &[&RouteHop]) {}
@@ -129,33 +138,34 @@ use crate::Invoice;
 use bitcoin_hashes::Hash;
 use bitcoin_hashes::sha256::Hash as Sha256;
 
+use crate::prelude::*;
 use lightning::ln::{PaymentHash, PaymentPreimage, PaymentSecret};
 use lightning::ln::channelmanager::{ChannelDetails, PaymentId, PaymentSendFailure};
 use lightning::ln::msgs::LightningError;
 use lightning::routing::scoring::{LockableScore, Score};
-use lightning::routing::router::{Payee, Route, RouteParameters};
+use lightning::routing::router::{PaymentParameters, Route, RouteParameters};
 use lightning::util::events::{Event, EventHandler};
 use lightning::util::logger::Logger;
+use crate::sync::Mutex;
 
 use secp256k1::key::PublicKey;
 
-use std::collections::hash_map::{self, HashMap};
-use std::ops::Deref;
-use std::sync::Mutex;
-use std::time::{Duration, SystemTime};
+use core::ops::Deref;
+use core::time::Duration;
+#[cfg(feature = "std")]
+use std::time::SystemTime;
 
 /// A utility for paying [`Invoice`]s and sending spontaneous payments.
 ///
 /// See [module-level documentation] for details.
 ///
 /// [module-level documentation]: crate::payment
-pub struct InvoicePayer<P: Deref, R, S: Deref, L: Deref, E>
+pub struct InvoicePayer<P: Deref, R, S: Deref, L: Deref, E: EventHandler>
 where
        P::Target: Payer,
        R: for <'a> Router<<<S as Deref>::Target as LockableScore<'a>>::Locked>,
        S::Target: for <'a> LockableScore<'a>,
        L::Target: Logger,
-       E: EventHandler,
 {
        payer: P,
        router: R,
@@ -187,13 +197,16 @@ pub trait Payer {
 
        /// Retries a failed payment path for the [`PaymentId`] using the given [`Route`].
        fn retry_payment(&self, route: &Route, payment_id: PaymentId) -> Result<(), PaymentSendFailure>;
+
+       /// Signals that no further retries for the given payment will occur.
+       fn abandon_payment(&self, payment_id: PaymentId);
 }
 
 /// A trait defining behavior for routing an [`Invoice`] payment.
 pub trait Router<S: Score> {
        /// Finds a [`Route`] between `payer` and `payee` for a payment with the given values.
        fn find_route(
-               &self, payer: &PublicKey, params: &RouteParameters, payment_hash: &PaymentHash,
+               &self, payer: &PublicKey, route_params: &RouteParameters, payment_hash: &PaymentHash,
                first_hops: Option<&[&ChannelDetails]>, scorer: &S
        ) -> Result<Route, LightningError>;
 }
@@ -217,13 +230,12 @@ pub enum PaymentError {
        Sending(PaymentSendFailure),
 }
 
-impl<P: Deref, R, S: Deref, L: Deref, E> InvoicePayer<P, R, S, L, E>
+impl<P: Deref, R, S: Deref, L: Deref, E: EventHandler> InvoicePayer<P, R, S, L, E>
 where
        P::Target: Payer,
        R: for <'a> Router<<<S as Deref>::Target as LockableScore<'a>>::Locked>,
        S::Target: for <'a> LockableScore<'a>,
        L::Target: Logger,
-       E: EventHandler,
 {
        /// Creates an invoice payer that retries failed payment paths.
        ///
@@ -284,14 +296,14 @@ where
                };
 
                let payment_secret = Some(invoice.payment_secret().clone());
-               let mut payee = Payee::from_node_id(invoice.recover_payee_pub_key())
+               let mut payment_params = PaymentParameters::from_node_id(invoice.recover_payee_pub_key())
                        .with_expiry_time(expiry_time_from_unix_epoch(&invoice).as_secs())
                        .with_route_hints(invoice.route_hints());
                if let Some(features) = invoice.features() {
-                       payee = payee.with_features(features.clone());
+                       payment_params = payment_params.with_features(features.clone());
                }
-               let params = RouteParameters {
-                       payee,
+               let route_params = RouteParameters {
+                       payment_params,
                        final_value_msat: invoice.amount_milli_satoshis().or(amount_msats).unwrap(),
                        final_cltv_expiry_delta: invoice.min_final_cltv_expiry() as u32,
                };
@@ -299,7 +311,7 @@ where
                let send_payment = |route: &Route| {
                        self.payer.send_payment(route, payment_hash, &payment_secret)
                };
-               self.pay_internal(&params, payment_hash, send_payment)
+               self.pay_internal(&route_params, payment_hash, send_payment)
                        .map_err(|e| { self.payment_cache.lock().unwrap().remove(&payment_hash); e })
        }
 
@@ -318,8 +330,8 @@ where
                        hash_map::Entry::Vacant(entry) => entry.insert(0),
                };
 
-               let params = RouteParameters {
-                       payee: Payee::for_keysend(pubkey),
+               let route_params = RouteParameters {
+                       payment_params: PaymentParameters::for_keysend(pubkey),
                        final_value_msat: amount_msats,
                        final_cltv_expiry_delta,
                };
@@ -327,16 +339,18 @@ where
                let send_payment = |route: &Route| {
                        self.payer.send_spontaneous_payment(route, payment_preimage)
                };
-               self.pay_internal(&params, payment_hash, send_payment)
+               self.pay_internal(&route_params, payment_hash, send_payment)
                        .map_err(|e| { self.payment_cache.lock().unwrap().remove(&payment_hash); e })
        }
 
        fn pay_internal<F: FnOnce(&Route) -> Result<PaymentId, PaymentSendFailure> + Copy>(
                &self, params: &RouteParameters, payment_hash: PaymentHash, send_payment: F,
        ) -> Result<PaymentId, PaymentError> {
-               if has_expired(params) {
-                       log_trace!(self.logger, "Invoice expired prior to send for payment {}", log_bytes!(payment_hash.0));
-                       return Err(PaymentError::Invoice("Invoice expired prior to send"));
+               #[cfg(feature = "std")] {
+                       if has_expired(params) {
+                               log_trace!(self.logger, "Invoice expired prior to send for payment {}", log_bytes!(payment_hash.0));
+                               return Err(PaymentError::Invoice("Invoice expired prior to send"));
+                       }
                }
 
                let payer = self.payer.node_id();
@@ -358,7 +372,7 @@ where
                                                Err(e)
                                        } else {
                                                *retry_count += 1;
-                                               std::mem::drop(payment_cache);
+                                               core::mem::drop(payment_cache);
                                                Ok(self.pay_internal(params, payment_hash, send_payment)?)
                                        }
                                },
@@ -396,9 +410,11 @@ where
                        return Err(());
                }
 
-               if has_expired(params) {
-                       log_trace!(self.logger, "Invoice expired for payment {}; not retrying (attempts: {})", log_bytes!(payment_hash.0), attempts);
-                       return Err(());
+               #[cfg(feature = "std")] {
+                       if has_expired(params) {
+                               log_trace!(self.logger, "Invoice expired for payment {}; not retrying (attempts: {})", log_bytes!(payment_hash.0), attempts);
+                               return Err(());
+                       }
                }
 
                let payer = self.payer.node_id();
@@ -442,46 +458,50 @@ where
 }
 
 fn expiry_time_from_unix_epoch(invoice: &Invoice) -> Duration {
-       invoice.timestamp().duration_since(SystemTime::UNIX_EPOCH).unwrap() + invoice.expiry_time()
+       invoice.signed_invoice.raw_invoice.data.timestamp.0 + invoice.expiry_time()
 }
 
-fn has_expired(params: &RouteParameters) -> bool {
-       if let Some(expiry_time) = params.payee.expiry_time {
+#[cfg(feature = "std")]
+fn has_expired(route_params: &RouteParameters) -> bool {
+       if let Some(expiry_time) = route_params.payment_params.expiry_time {
                Invoice::is_expired_from_epoch(&SystemTime::UNIX_EPOCH, Duration::from_secs(expiry_time))
        } else { false }
 }
 
-impl<P: Deref, R, S: Deref, L: Deref, E> EventHandler for InvoicePayer<P, R, S, L, E>
+impl<P: Deref, R, S: Deref, L: Deref, E: EventHandler> EventHandler for InvoicePayer<P, R, S, L, E>
 where
        P::Target: Payer,
        R: for <'a> Router<<<S as Deref>::Target as LockableScore<'a>>::Locked>,
        S::Target: for <'a> LockableScore<'a>,
        L::Target: Logger,
-       E: EventHandler,
 {
        fn handle_event(&self, event: &Event) {
                match event {
                        Event::PaymentPathFailed {
-                               all_paths_failed, payment_id, payment_hash, rejected_by_dest, path,
-                               short_channel_id, retry, ..
+                               payment_id, payment_hash, rejected_by_dest, path, short_channel_id, retry, ..
                        } => {
                                if let Some(short_channel_id) = short_channel_id {
                                        let path = path.iter().collect::<Vec<_>>();
                                        self.scorer.lock().payment_path_failed(&path, *short_channel_id);
                                }
 
-                               if *rejected_by_dest {
-                                       log_trace!(self.logger, "Payment {} rejected by destination; not retrying", log_bytes!(payment_hash.0));
-                               } else if payment_id.is_none() {
+                               if payment_id.is_none() {
                                        log_trace!(self.logger, "Payment {} has no id; not retrying", log_bytes!(payment_hash.0));
+                               } else if *rejected_by_dest {
+                                       log_trace!(self.logger, "Payment {} rejected by destination; not retrying", log_bytes!(payment_hash.0));
+                                       self.payer.abandon_payment(payment_id.unwrap());
                                } else if retry.is_none() {
                                        log_trace!(self.logger, "Payment {} missing retry params; not retrying", log_bytes!(payment_hash.0));
+                                       self.payer.abandon_payment(payment_id.unwrap());
                                } else if self.retry_payment(payment_id.unwrap(), *payment_hash, retry.as_ref().unwrap()).is_ok() {
                                        // We retried at least somewhat, don't provide the PaymentPathFailed event to the user.
                                        return;
+                               } else {
+                                       self.payer.abandon_payment(payment_id.unwrap());
                                }
-
-                               if *all_paths_failed { self.payment_cache.lock().unwrap().remove(payment_hash); }
+                       },
+                       Event::PaymentFailed { payment_hash, .. } => {
+                               self.remove_cached_payment(&payment_hash);
                        },
                        Event::PaymentPathSuccessful { path, .. } => {
                                let path = path.iter().collect::<Vec<_>>();
@@ -505,31 +525,33 @@ where
 #[cfg(test)]
 mod tests {
        use super::*;
-       use crate::{DEFAULT_EXPIRY_TIME, InvoiceBuilder, Currency};
-       use utils::create_invoice_from_channelmanager;
+       use crate::{InvoiceBuilder, Currency};
+       use utils::create_invoice_from_channelmanager_and_duration_since_epoch;
        use bitcoin_hashes::sha256::Hash as Sha256;
        use lightning::ln::PaymentPreimage;
        use lightning::ln::features::{ChannelFeatures, NodeFeatures, InitFeatures};
        use lightning::ln::functional_test_utils::*;
-       use lightning::ln::msgs::{ErrorAction, LightningError};
+       use lightning::ln::msgs::{ChannelMessageHandler, ErrorAction, LightningError};
        use lightning::routing::network_graph::NodeId;
-       use lightning::routing::router::{Payee, Route, RouteHop};
+       use lightning::routing::router::{PaymentParameters, Route, RouteHop};
        use lightning::util::test_utils::TestLogger;
        use lightning::util::errors::APIError;
-       use lightning::util::events::{Event, MessageSendEventsProvider};
+       use lightning::util::events::{Event, EventsProvider, MessageSendEvent, MessageSendEventsProvider};
        use secp256k1::{SecretKey, PublicKey, Secp256k1};
        use std::cell::RefCell;
        use std::collections::VecDeque;
        use std::time::{SystemTime, Duration};
+       use DEFAULT_EXPIRY_TIME;
 
        fn invoice(payment_preimage: PaymentPreimage) -> Invoice {
                let payment_hash = Sha256::hash(&payment_preimage.0);
                let private_key = SecretKey::from_slice(&[42; 32]).unwrap();
+
                InvoiceBuilder::new(Currency::Bitcoin)
                        .description("test".into())
                        .payment_hash(payment_hash)
                        .payment_secret(PaymentSecret([0; 32]))
-                       .current_timestamp()
+                       .duration_since_epoch(duration_since_epoch())
                        .min_final_cltv_expiry(144)
                        .amount_milli_satoshis(128)
                        .build_signed(|hash| {
@@ -538,14 +560,24 @@ mod tests {
                        .unwrap()
        }
 
+       fn duration_since_epoch() -> Duration {
+               #[cfg(feature = "std")]
+                       let duration_since_epoch =
+                       SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap();
+               #[cfg(not(feature = "std"))]
+                       let duration_since_epoch = Duration::from_secs(1234567);
+               duration_since_epoch
+       }
+
        fn zero_value_invoice(payment_preimage: PaymentPreimage) -> Invoice {
                let payment_hash = Sha256::hash(&payment_preimage.0);
                let private_key = SecretKey::from_slice(&[42; 32]).unwrap();
+
                InvoiceBuilder::new(Currency::Bitcoin)
                        .description("test".into())
                        .payment_hash(payment_hash)
                        .payment_secret(PaymentSecret([0; 32]))
-                       .current_timestamp()
+                       .duration_since_epoch(duration_since_epoch())
                        .min_final_cltv_expiry(144)
                        .build_signed(|hash| {
                                Secp256k1::new().sign_recoverable(hash, &private_key)
@@ -553,17 +585,18 @@ mod tests {
                        .unwrap()
        }
 
+       #[cfg(feature = "std")]
        fn expired_invoice(payment_preimage: PaymentPreimage) -> Invoice {
                let payment_hash = Sha256::hash(&payment_preimage.0);
                let private_key = SecretKey::from_slice(&[42; 32]).unwrap();
-               let timestamp = SystemTime::now()
+               let duration = duration_since_epoch()
                        .checked_sub(Duration::from_secs(DEFAULT_EXPIRY_TIME * 2))
                        .unwrap();
                InvoiceBuilder::new(Currency::Bitcoin)
                        .description("test".into())
                        .payment_hash(payment_hash)
                        .payment_secret(PaymentSecret([0; 32]))
-                       .timestamp(timestamp)
+                       .duration_since_epoch(duration)
                        .min_final_cltv_expiry(144)
                        .amount_milli_satoshis(128)
                        .build_signed(|hash| {
@@ -806,6 +839,8 @@ mod tests {
                assert_eq!(*payer.attempts.borrow(), 1);
        }
 
+       // Expiration is checked only in an std environment
+       #[cfg(feature = "std")]
        #[test]
        fn fails_paying_invoice_after_expiration() {
                let event_handled = core::cell::RefCell::new(false);
@@ -825,6 +860,8 @@ mod tests {
                } else { panic!("Expected Invoice Error"); }
        }
 
+       // Expiration is checked only in an std environment
+       #[cfg(feature = "std")]
        #[test]
        fn fails_retrying_invoice_after_expiration() {
                let event_handled = core::cell::RefCell::new(false);
@@ -845,7 +882,7 @@ mod tests {
                assert_eq!(*payer.attempts.borrow(), 1);
 
                let mut retry_data = TestRouter::retry_for_invoice(&invoice);
-               retry_data.payee.expiry_time = Some(SystemTime::now()
+               retry_data.payment_params.expiry_time = Some(SystemTime::now()
                        .checked_sub(Duration::from_secs(2)).unwrap()
                        .duration_since(SystemTime::UNIX_EPOCH).unwrap().as_secs());
                let event = Event::PaymentPathFailed {
@@ -1099,7 +1136,7 @@ mod tests {
                assert_eq!(*payer.attempts.borrow(), 1);
 
                let retry = RouteParameters {
-                       payee: Payee::for_keysend(pubkey),
+                       payment_params: PaymentParameters::for_keysend(pubkey),
                        final_value_msat,
                        final_cltv_expiry_delta,
                };
@@ -1214,7 +1251,7 @@ mod tests {
                                                short_channel_id: 1, fee_msat: final_value_msat / 2, cltv_expiry_delta: 144
                                        }],
                                ],
-                               payee: None,
+                               payment_params: None,
                        }
                }
 
@@ -1223,15 +1260,15 @@ mod tests {
                }
 
                fn retry_for_invoice(invoice: &Invoice) -> RouteParameters {
-                       let mut payee = Payee::from_node_id(invoice.recover_payee_pub_key())
+                       let mut payment_params = PaymentParameters::from_node_id(invoice.recover_payee_pub_key())
                                .with_expiry_time(expiry_time_from_unix_epoch(invoice).as_secs())
                                .with_route_hints(invoice.route_hints());
                        if let Some(features) = invoice.features() {
-                               payee = payee.with_features(features.clone());
+                               payment_params = payment_params.with_features(features.clone());
                        }
                        let final_value_msat = invoice.amount_milli_satoshis().unwrap() / 2;
                        RouteParameters {
-                               payee,
+                               payment_params,
                                final_value_msat,
                                final_cltv_expiry_delta: invoice.min_final_cltv_expiry() as u32,
                        }
@@ -1240,11 +1277,11 @@ mod tests {
 
        impl<S: Score> Router<S> for TestRouter {
                fn find_route(
-                       &self, _payer: &PublicKey, params: &RouteParameters, _payment_hash: &PaymentHash,
+                       &self, _payer: &PublicKey, route_params: &RouteParameters, _payment_hash: &PaymentHash,
                        _first_hops: Option<&[&ChannelDetails]>, _scorer: &S
                ) -> Result<Route, LightningError> {
                        Ok(Route {
-                               payee: Some(params.payee.clone()), ..Self::route_for_value(params.final_value_msat)
+                               payment_params: Some(route_params.payment_params.clone()), ..Self::route_for_value(route_params.final_value_msat)
                        })
                }
        }
@@ -1290,7 +1327,7 @@ mod tests {
 
        impl Score for TestScorer {
                fn channel_penalty_msat(
-                       &self, _short_channel_id: u64, _send_amt: u64, _chan_amt: Option<u64>, _source: &NodeId, _target: &NodeId
+                       &self, _short_channel_id: u64, _send_amt: u64, _chan_amt: u64, _source: &NodeId, _target: &NodeId
                ) -> u64 { 0 }
 
                fn payment_path_failed(&mut self, actual_path: &[&RouteHop], actual_short_channel_id: u64) {
@@ -1447,6 +1484,8 @@ mod tests {
                        self.check_value_msats(Amount::OnRetry(route.get_total_amount()));
                        self.check_attempts().map(|_| ())
                }
+
+               fn abandon_payment(&self, _payment_id: PaymentId) { }
        }
 
        // *** Full Featured Functional Tests with a Real ChannelManager ***
@@ -1504,7 +1543,7 @@ mod tests {
                                        cltv_expiry_delta: 100,
                                }],
                        ],
-                       payee: Some(Payee::from_node_id(nodes[1].node.get_our_node_id())),
+                       payment_params: Some(PaymentParameters::from_node_id(nodes[1].node.get_our_node_id())),
                };
                let router = ManualRouter(RefCell::new(VecDeque::new()));
                router.expect_find_route(Ok(route.clone()));
@@ -1517,8 +1556,9 @@ mod tests {
                let scorer = RefCell::new(TestScorer::new());
                let invoice_payer = InvoicePayer::new(nodes[0].node, router, &scorer, nodes[0].logger, event_handler, RetryAttempts(1));
 
-               assert!(invoice_payer.pay_invoice(&create_invoice_from_channelmanager(
-                       &nodes[1].node, nodes[1].keys_manager, Currency::Bitcoin, Some(100_010_000), "Invoice".to_string()).unwrap())
+               assert!(invoice_payer.pay_invoice(&create_invoice_from_channelmanager_and_duration_since_epoch(
+                       &nodes[1].node, nodes[1].keys_manager, Currency::Bitcoin, Some(100_010_000), "Invoice".to_string(),
+                       duration_since_epoch()).unwrap())
                        .is_ok());
                let htlc_msgs = nodes[0].node.get_and_clear_pending_msg_events();
                assert_eq!(htlc_msgs.len(), 2);
@@ -1547,7 +1587,7 @@ mod tests {
                                        cltv_expiry_delta: 100,
                                }],
                        ],
-                       payee: Some(Payee::from_node_id(nodes[1].node.get_our_node_id())),
+                       payment_params: Some(PaymentParameters::from_node_id(nodes[1].node.get_our_node_id())),
                };
                let router = ManualRouter(RefCell::new(VecDeque::new()));
                router.expect_find_route(Ok(route.clone()));
@@ -1562,11 +1602,186 @@ mod tests {
                let scorer = RefCell::new(TestScorer::new());
                let invoice_payer = InvoicePayer::new(nodes[0].node, router, &scorer, nodes[0].logger, event_handler, RetryAttempts(1));
 
-               assert!(invoice_payer.pay_invoice(&create_invoice_from_channelmanager(
-                       &nodes[1].node, nodes[1].keys_manager, Currency::Bitcoin, Some(100_010_000), "Invoice".to_string()).unwrap())
+               assert!(invoice_payer.pay_invoice(&create_invoice_from_channelmanager_and_duration_since_epoch(
+                       &nodes[1].node, nodes[1].keys_manager, Currency::Bitcoin, Some(100_010_000), "Invoice".to_string(),
+                       duration_since_epoch()).unwrap())
                        .is_ok());
                let htlc_msgs = nodes[0].node.get_and_clear_pending_msg_events();
                assert_eq!(htlc_msgs.len(), 2);
                check_added_monitors!(nodes[0], 2);
        }
+
+       #[test]
+       fn no_extra_retries_on_back_to_back_fail() {
+               // In a previous release, we had a race where we may exceed the payment retry count if we
+               // get two failures in a row with the second having `all_paths_failed` set.
+               // Generally, when we give up trying to retry a payment, we don't know for sure what the
+               // current state of the ChannelManager event queue is. Specifically, we cannot be sure that
+               // there are not multiple additional `PaymentPathFailed` or even `PaymentSent` events
+               // pending which we will see later. Thus, when we previously removed the retry tracking map
+               // entry after a `all_paths_failed` `PaymentPathFailed` event, we may have dropped the
+               // retry entry even though more events for the same payment were still pending. This led to
+               // us retrying a payment again even though we'd already given up on it.
+               //
+               // We now have a separate event - `PaymentFailed` which indicates no HTLCs remain and which
+               // is used to remove the payment retry counter entries instead. This tests for the specific
+               // excess-retry case while also testing `PaymentFailed` generation.
+
+               let chanmon_cfgs = create_chanmon_cfgs(3);
+               let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
+               let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
+               let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
+
+               let chan_1_scid = create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 10_000_000, 0, InitFeatures::known(), InitFeatures::known()).0.contents.short_channel_id;
+               let chan_2_scid = create_announced_chan_between_nodes_with_value(&nodes, 1, 2, 10_000_000, 0, InitFeatures::known(), InitFeatures::known()).0.contents.short_channel_id;
+
+               let mut route = Route {
+                       paths: vec![
+                               vec![RouteHop {
+                                       pubkey: nodes[1].node.get_our_node_id(),
+                                       node_features: NodeFeatures::known(),
+                                       short_channel_id: chan_1_scid,
+                                       channel_features: ChannelFeatures::known(),
+                                       fee_msat: 0,
+                                       cltv_expiry_delta: 100,
+                               }, RouteHop {
+                                       pubkey: nodes[2].node.get_our_node_id(),
+                                       node_features: NodeFeatures::known(),
+                                       short_channel_id: chan_2_scid,
+                                       channel_features: ChannelFeatures::known(),
+                                       fee_msat: 100_000_000,
+                                       cltv_expiry_delta: 100,
+                               }],
+                               vec![RouteHop {
+                                       pubkey: nodes[1].node.get_our_node_id(),
+                                       node_features: NodeFeatures::known(),
+                                       short_channel_id: chan_1_scid,
+                                       channel_features: ChannelFeatures::known(),
+                                       fee_msat: 0,
+                                       cltv_expiry_delta: 100,
+                               }, RouteHop {
+                                       pubkey: nodes[2].node.get_our_node_id(),
+                                       node_features: NodeFeatures::known(),
+                                       short_channel_id: chan_2_scid,
+                                       channel_features: ChannelFeatures::known(),
+                                       fee_msat: 100_000_000,
+                                       cltv_expiry_delta: 100,
+                               }]
+                       ],
+                       payment_params: Some(PaymentParameters::from_node_id(nodes[2].node.get_our_node_id())),
+               };
+               let router = ManualRouter(RefCell::new(VecDeque::new()));
+               router.expect_find_route(Ok(route.clone()));
+               // On retry, we'll only be asked for one path
+               route.paths.remove(1);
+               router.expect_find_route(Ok(route.clone()));
+
+               let expected_events: RefCell<VecDeque<&dyn Fn(&Event)>> = RefCell::new(VecDeque::new());
+               let event_handler = |event: &Event| {
+                       let event_checker = expected_events.borrow_mut().pop_front().unwrap();
+                       event_checker(event);
+               };
+               let scorer = RefCell::new(TestScorer::new());
+               let invoice_payer = InvoicePayer::new(nodes[0].node, router, &scorer, nodes[0].logger, event_handler, RetryAttempts(1));
+
+               assert!(invoice_payer.pay_invoice(&create_invoice_from_channelmanager_and_duration_since_epoch(
+                       &nodes[1].node, nodes[1].keys_manager, Currency::Bitcoin, Some(100_010_000), "Invoice".to_string(),
+                       duration_since_epoch()).unwrap())
+                       .is_ok());
+               let htlc_updates = SendEvent::from_node(&nodes[0]);
+               check_added_monitors!(nodes[0], 1);
+               assert_eq!(htlc_updates.msgs.len(), 1);
+
+               nodes[1].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &htlc_updates.msgs[0]);
+               nodes[1].node.handle_commitment_signed(&nodes[0].node.get_our_node_id(), &htlc_updates.commitment_msg);
+               check_added_monitors!(nodes[1], 1);
+               let (bs_first_raa, bs_first_cs) = get_revoke_commit_msgs!(nodes[1], nodes[0].node.get_our_node_id());
+
+               nodes[0].node.handle_revoke_and_ack(&nodes[1].node.get_our_node_id(), &bs_first_raa);
+               check_added_monitors!(nodes[0], 1);
+               let second_htlc_updates = SendEvent::from_node(&nodes[0]);
+
+               nodes[0].node.handle_commitment_signed(&nodes[1].node.get_our_node_id(), &bs_first_cs);
+               check_added_monitors!(nodes[0], 1);
+               let as_first_raa = get_event_msg!(nodes[0], MessageSendEvent::SendRevokeAndACK, nodes[1].node.get_our_node_id());
+
+               nodes[1].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &second_htlc_updates.msgs[0]);
+               nodes[1].node.handle_commitment_signed(&nodes[0].node.get_our_node_id(), &second_htlc_updates.commitment_msg);
+               check_added_monitors!(nodes[1], 1);
+               let bs_second_raa = get_event_msg!(nodes[1], MessageSendEvent::SendRevokeAndACK, nodes[0].node.get_our_node_id());
+
+               nodes[1].node.handle_revoke_and_ack(&nodes[0].node.get_our_node_id(), &as_first_raa);
+               check_added_monitors!(nodes[1], 1);
+               let bs_fail_update = get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id());
+
+               nodes[0].node.handle_revoke_and_ack(&nodes[1].node.get_our_node_id(), &bs_second_raa);
+               check_added_monitors!(nodes[0], 1);
+
+               nodes[0].node.handle_update_fail_htlc(&nodes[1].node.get_our_node_id(), &bs_fail_update.update_fail_htlcs[0]);
+               nodes[0].node.handle_commitment_signed(&nodes[1].node.get_our_node_id(), &bs_fail_update.commitment_signed);
+               check_added_monitors!(nodes[0], 1);
+               let (as_second_raa, as_third_cs) = get_revoke_commit_msgs!(nodes[0], nodes[1].node.get_our_node_id());
+
+               nodes[1].node.handle_revoke_and_ack(&nodes[0].node.get_our_node_id(), &as_second_raa);
+               check_added_monitors!(nodes[1], 1);
+               let bs_second_fail_update = get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id());
+
+               nodes[1].node.handle_commitment_signed(&nodes[0].node.get_our_node_id(), &as_third_cs);
+               check_added_monitors!(nodes[1], 1);
+               let bs_third_raa = get_event_msg!(nodes[1], MessageSendEvent::SendRevokeAndACK, nodes[0].node.get_our_node_id());
+
+               nodes[0].node.handle_update_fail_htlc(&nodes[1].node.get_our_node_id(), &bs_second_fail_update.update_fail_htlcs[0]);
+               nodes[0].node.handle_commitment_signed(&nodes[1].node.get_our_node_id(), &bs_second_fail_update.commitment_signed);
+               check_added_monitors!(nodes[0], 1);
+
+               nodes[0].node.handle_revoke_and_ack(&nodes[1].node.get_our_node_id(), &bs_third_raa);
+               check_added_monitors!(nodes[0], 1);
+               let (as_third_raa, as_fourth_cs) = get_revoke_commit_msgs!(nodes[0], nodes[1].node.get_our_node_id());
+
+               nodes[1].node.handle_revoke_and_ack(&nodes[0].node.get_our_node_id(), &as_third_raa);
+               check_added_monitors!(nodes[1], 1);
+               nodes[1].node.handle_commitment_signed(&nodes[0].node.get_our_node_id(), &as_fourth_cs);
+               check_added_monitors!(nodes[1], 1);
+               let bs_fourth_raa = get_event_msg!(nodes[1], MessageSendEvent::SendRevokeAndACK, nodes[0].node.get_our_node_id());
+
+               nodes[0].node.handle_revoke_and_ack(&nodes[1].node.get_our_node_id(), &bs_fourth_raa);
+               check_added_monitors!(nodes[0], 1);
+
+               // At this point A has sent two HTLCs which both failed due to lack of fee. It now has two
+               // pending `PaymentPathFailed` events, one with `all_paths_failed` unset, and the second
+               // with it set. The first event will use up the only retry we are allowed, with the second
+               // `PaymentPathFailed` being passed up to the user (us, in this case). Previously, we'd
+               // treated this as "HTLC complete" and dropped the retry counter, causing us to retry again
+               // if the final HTLC failed.
+               expected_events.borrow_mut().push_back(&|ev: &Event| {
+                       if let Event::PaymentPathFailed { rejected_by_dest, all_paths_failed, .. } = ev {
+                               assert!(!rejected_by_dest);
+                               assert!(all_paths_failed);
+                       } else { panic!("Unexpected event"); }
+               });
+               nodes[0].node.process_pending_events(&invoice_payer);
+               assert!(expected_events.borrow().is_empty());
+
+               let retry_htlc_updates = SendEvent::from_node(&nodes[0]);
+               check_added_monitors!(nodes[0], 1);
+
+               nodes[1].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &retry_htlc_updates.msgs[0]);
+               commitment_signed_dance!(nodes[1], nodes[0], &retry_htlc_updates.commitment_msg, false, true);
+               let bs_fail_update = get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id());
+               nodes[0].node.handle_update_fail_htlc(&nodes[1].node.get_our_node_id(), &bs_fail_update.update_fail_htlcs[0]);
+               commitment_signed_dance!(nodes[0], nodes[1], &bs_fail_update.commitment_signed, false, true);
+
+               expected_events.borrow_mut().push_back(&|ev: &Event| {
+                       if let Event::PaymentPathFailed { rejected_by_dest, all_paths_failed, .. } = ev {
+                               assert!(!rejected_by_dest);
+                               assert!(all_paths_failed);
+                       } else { panic!("Unexpected event"); }
+               });
+               expected_events.borrow_mut().push_back(&|ev: &Event| {
+                       if let Event::PaymentFailed { .. } = ev {
+                       } else { panic!("Unexpected event"); }
+               });
+               nodes[0].node.process_pending_events(&invoice_payer);
+               assert!(expected_events.borrow().is_empty());
+       }
 }