Merge pull request #2025 from TheBlueMatt/2023-02-no-pub-genesis-hashes
[rust-lightning] / lightning / src / ln / outbound_payment.rs
index 361adfaf66c3eab2b4a78678a6d7b5ffe5dfb81c..81b95f1ce07230ccd7b46339fd7c28ea6bcaba8e 100644 (file)
@@ -64,13 +64,8 @@ pub(crate) enum PendingOutboundPayment {
                payment_hash: Option<PaymentHash>,
                timer_ticks_without_htlcs: u8,
        },
-       /// When a payer gives up trying to retry a payment, they inform us, letting us generate a
-       /// `PaymentFailed` event when all HTLCs have irrevocably failed. This avoids a number of race
-       /// conditions in MPP-aware payment retriers (1), where the possibility of multiple
-       /// `PaymentPathFailed` events with `all_paths_failed` can be pending at once, confusing a
-       /// downstream event handler as to when a payment has actually failed.
-       ///
-       /// (1) <https://github.com/lightningdevkit/rust-lightning/issues/1164>
+       /// When we've decided to give up retrying a payment, we mark it as abandoned so we can eventually
+       /// generate a `PaymentFailed` event when all HTLCs have irrevocably failed.
        Abandoned {
                session_privs: HashSet<[u8; 32]>,
                payment_hash: PaymentHash,
@@ -240,7 +235,10 @@ pub enum Retry {
        /// were retried along a route from a single call to [`Router::find_route`].
        Attempts(usize),
        #[cfg(not(feature = "no-std"))]
-       /// Time elapsed before abandoning retries for a payment.
+       /// Time elapsed before abandoning retries for a payment. At least one attempt at payment is made;
+       /// see [`PaymentParameters::expiry_time`] to avoid any attempt at payment after a specific time.
+       ///
+       /// [`PaymentParameters::expiry_time`]: crate::routing::router::PaymentParameters::expiry_time
        Timeout(core::time::Duration),
 }
 
@@ -312,9 +310,35 @@ impl<T: Time> Display for PaymentAttemptsUsingTime<T> {
        }
 }
 
-/// If a payment fails to send, it can be in one of several states. This enum is returned as the
-/// Err() type describing which state the payment is in, see the description of individual enum
-/// states for more.
+/// Indicates an immediate error on [`ChannelManager::send_payment_with_retry`]. Further errors
+/// may be surfaced later via [`Event::PaymentPathFailed`] and [`Event::PaymentFailed`].
+///
+/// [`ChannelManager::send_payment_with_retry`]: crate::ln::channelmanager::ChannelManager::send_payment_with_retry
+/// [`Event::PaymentPathFailed`]: crate::util::events::Event::PaymentPathFailed
+/// [`Event::PaymentFailed`]: crate::util::events::Event::PaymentFailed
+#[derive(Clone, Debug)]
+pub enum RetryableSendFailure {
+       /// The provided [`PaymentParameters::expiry_time`] indicated that the payment has expired. Note
+       /// that this error is *not* caused by [`Retry::Timeout`].
+       ///
+       /// [`PaymentParameters::expiry_time`]: crate::routing::router::PaymentParameters::expiry_time
+       PaymentExpired,
+       /// We were unable to find a route to the destination.
+       RouteNotFound,
+       /// Indicates that a payment for the provided [`PaymentId`] is already in-flight and has not
+       /// yet completed (i.e. generated an [`Event::PaymentSent`] or [`Event::PaymentFailed`]).
+       ///
+       /// [`PaymentId`]: crate::ln::channelmanager::PaymentId
+       /// [`Event::PaymentSent`]: crate::util::events::Event::PaymentSent
+       /// [`Event::PaymentFailed`]: crate::util::events::Event::PaymentFailed
+       DuplicatePayment,
+}
+
+/// If a payment fails to send with [`ChannelManager::send_payment`], it can be in one of several
+/// states. This enum is returned as the Err() type describing which state the payment is in, see
+/// the description of individual enum states for more.
+///
+/// [`ChannelManager::send_payment`]: crate::ln::channelmanager::ChannelManager::send_payment
 #[derive(Clone, Debug)]
 pub enum PaymentSendFailure {
        /// A parameter which was passed to send_payment was invalid, preventing us from attempting to
@@ -397,8 +421,9 @@ impl OutboundPayments {
                &self, payment_hash: PaymentHash, payment_secret: &Option<PaymentSecret>, payment_id: PaymentId,
                retry_strategy: Retry, route_params: RouteParameters, router: &R,
                first_hops: Vec<ChannelDetails>, compute_inflight_htlcs: IH, entropy_source: &ES,
-               node_signer: &NS, best_block_height: u32, logger: &L, send_payment_along_path: SP,
-       ) -> Result<(), PaymentSendFailure>
+               node_signer: &NS, best_block_height: u32, logger: &L,
+               pending_events: &Mutex<Vec<events::Event>>, send_payment_along_path: SP,
+       ) -> Result<(), RetryableSendFailure>
        where
                R::Target: Router,
                ES::Target: EntropySource,
@@ -408,10 +433,9 @@ impl OutboundPayments {
                SP: Fn(&Vec<RouteHop>, &Option<PaymentParameters>, &PaymentHash, &Option<PaymentSecret>, u64,
                         u32, PaymentId, &Option<PaymentPreimage>, [u8; 32]) -> Result<(), APIError>,
        {
-               self.pay_internal(payment_id, Some((payment_hash, payment_secret, None, retry_strategy)),
+               self.send_payment_internal(payment_id, payment_hash, payment_secret, None, retry_strategy,
                        route_params, router, first_hops, &compute_inflight_htlcs, entropy_source, node_signer,
-                       best_block_height, logger, &send_payment_along_path)
-                       .map_err(|e| { self.remove_outbound_if_all_failed(payment_id, &e); e })
+                       best_block_height, logger, pending_events, &send_payment_along_path)
        }
 
        pub(super) fn send_payment_with_route<ES: Deref, NS: Deref, F>(
@@ -435,8 +459,9 @@ impl OutboundPayments {
                &self, payment_preimage: Option<PaymentPreimage>, payment_id: PaymentId,
                retry_strategy: Retry, route_params: RouteParameters, router: &R,
                first_hops: Vec<ChannelDetails>, inflight_htlcs: IH, entropy_source: &ES,
-               node_signer: &NS, best_block_height: u32, logger: &L, send_payment_along_path: SP
-       ) -> Result<PaymentHash, PaymentSendFailure>
+               node_signer: &NS, best_block_height: u32, logger: &L,
+               pending_events: &Mutex<Vec<events::Event>>, send_payment_along_path: SP
+       ) -> Result<PaymentHash, RetryableSendFailure>
        where
                R::Target: Router,
                ES::Target: EntropySource,
@@ -449,11 +474,10 @@ impl OutboundPayments {
                let preimage = payment_preimage
                        .unwrap_or_else(|| PaymentPreimage(entropy_source.get_secure_random_bytes()));
                let payment_hash = PaymentHash(Sha256::hash(&preimage.0).into_inner());
-               self.pay_internal(payment_id, Some((payment_hash, &None, Some(preimage), retry_strategy)),
-                       route_params, router, first_hops, &inflight_htlcs, entropy_source, node_signer,
-                       best_block_height, logger, &send_payment_along_path)
+               self.send_payment_internal(payment_id, payment_hash, &None, Some(preimage), retry_strategy,
+                       route_params, router, first_hops, inflight_htlcs, entropy_source, node_signer,
+                       best_block_height, logger, pending_events, send_payment_along_path)
                        .map(|()| payment_hash)
-                       .map_err(|e| { self.remove_outbound_if_all_failed(payment_id, &e); e })
        }
 
        pub(super) fn send_spontaneous_payment_with_route<ES: Deref, NS: Deref, F>(
@@ -520,12 +544,7 @@ impl OutboundPayments {
                        }
                        core::mem::drop(outbounds);
                        if let Some((payment_id, route_params)) = retry_id_route_params {
-                               if let Err(e) = self.pay_internal(payment_id, None, route_params, router, first_hops(), &inflight_htlcs, entropy_source, node_signer, best_block_height, logger, &send_payment_along_path) {
-                                       log_info!(logger, "Errored retrying payment: {:?}", e);
-                                       // If we error on retry, there is no chance of the payment succeeding and no HTLCs have
-                                       // been irrevocably committed to, so we can safely abandon.
-                                       self.abandon_payment(payment_id, pending_events);
-                               }
+                               self.retry_payment_internal(payment_id, route_params, router, first_hops(), &inflight_htlcs, entropy_source, node_signer, best_block_height, logger, pending_events, &send_payment_along_path)
                        } else { break }
                }
 
@@ -551,14 +570,18 @@ impl OutboundPayments {
                        !pmt.is_auto_retryable_now() && pmt.remaining_parts() == 0 && !pmt.is_fulfilled())
        }
 
-       /// Will return `Ok(())` iff at least one HTLC is sent for the payment.
-       fn pay_internal<R: Deref, NS: Deref, ES: Deref, IH, SP, L: Deref>(
-               &self, payment_id: PaymentId,
-               initial_send_info: Option<(PaymentHash, &Option<PaymentSecret>, Option<PaymentPreimage>, Retry)>,
-               route_params: RouteParameters, router: &R, first_hops: Vec<ChannelDetails>,
-               inflight_htlcs: &IH, entropy_source: &ES, node_signer: &NS, best_block_height: u32,
-               logger: &L, send_payment_along_path: &SP,
-       ) -> Result<(), PaymentSendFailure>
+       /// Errors immediately on [`RetryableSendFailure`] error conditions. Otherwise, further errors may
+       /// be surfaced asynchronously via [`Event::PaymentPathFailed`] and [`Event::PaymentFailed`].
+       ///
+       /// [`Event::PaymentPathFailed`]: crate::util::events::Event::PaymentPathFailed
+       /// [`Event::PaymentFailed`]: crate::util::events::Event::PaymentFailed
+       fn send_payment_internal<R: Deref, NS: Deref, ES: Deref, IH, SP, L: Deref>(
+               &self, payment_id: PaymentId, payment_hash: PaymentHash, payment_secret: &Option<PaymentSecret>,
+               keysend_preimage: Option<PaymentPreimage>, retry_strategy: Retry, route_params: RouteParameters,
+               router: &R, first_hops: Vec<ChannelDetails>, inflight_htlcs: IH, entropy_source: &ES,
+               node_signer: &NS, best_block_height: u32, logger: &L,
+               pending_events: &Mutex<Vec<events::Event>>, send_payment_along_path: SP,
+       ) -> Result<(), RetryableSendFailure>
        where
                R::Target: Router,
                ES::Target: EntropySource,
@@ -566,130 +589,223 @@ impl OutboundPayments {
                L::Target: Logger,
                IH: Fn() -> InFlightHtlcs,
                SP: Fn(&Vec<RouteHop>, &Option<PaymentParameters>, &PaymentHash, &Option<PaymentSecret>, u64,
-                  u32, PaymentId, &Option<PaymentPreimage>, [u8; 32]) -> Result<(), APIError>
+                   u32, PaymentId, &Option<PaymentPreimage>, [u8; 32]) -> Result<(), APIError>
        {
                #[cfg(feature = "std")] {
                        if has_expired(&route_params) {
-                               return Err(PaymentSendFailure::ParameterError(APIError::APIMisuseError {
-                                       err: format!("Invoice expired for payment id {}", log_bytes!(payment_id.0)),
-                               }))
+                               return Err(RetryableSendFailure::PaymentExpired)
                        }
                }
 
                let route = router.find_route(
                        &node_signer.get_node_id(Recipient::Node).unwrap(), &route_params,
-                       Some(&first_hops.iter().collect::<Vec<_>>()), &inflight_htlcs(),
-               ).map_err(|e| PaymentSendFailure::ParameterError(APIError::APIMisuseError {
-                       err: format!("Failed to find a route for payment {}: {:?}", log_bytes!(payment_id.0), e), // TODO: add APIError::RouteNotFound
-               }))?;
-
-               let res = if let Some((payment_hash, payment_secret, keysend_preimage, retry_strategy)) = initial_send_info {
-                       let onion_session_privs = self.add_new_pending_payment(payment_hash, *payment_secret, payment_id, keysend_preimage, &route, Some(retry_strategy), Some(route_params.payment_params.clone()), entropy_source, best_block_height)?;
-                       self.pay_route_internal(&route, payment_hash, payment_secret, None, payment_id, None, onion_session_privs, node_signer, best_block_height, send_payment_along_path)
-               } else {
-                       self.retry_payment_with_route(&route, payment_id, entropy_source, node_signer, best_block_height, send_payment_along_path)
-               };
-               match res {
-                       Err(PaymentSendFailure::AllFailedResendSafe(_)) => {
-                               let retry_res = self.pay_internal(payment_id, None, route_params, router, first_hops, inflight_htlcs, entropy_source, node_signer, best_block_height, logger, send_payment_along_path);
-                               log_info!(logger, "Result retrying payment id {}: {:?}", log_bytes!(payment_id.0), retry_res);
-                               if let Err(PaymentSendFailure::ParameterError(APIError::APIMisuseError { err })) = &retry_res {
-                                       if err.starts_with("Retries exhausted ") { return res; }
-                               }
-                               retry_res
-                       },
-                       Err(PaymentSendFailure::PartialFailure { failed_paths_retry: Some(retry), .. }) => {
-                               // Some paths were sent, even if we failed to send the full MPP value our recipient may
-                               // misbehave and claim the funds, at which point we have to consider the payment sent, so
-                               // return `Ok()` here, ignoring any retry errors.
-                               let retry_res = self.pay_internal(payment_id, None, retry, router, first_hops, inflight_htlcs, entropy_source, node_signer, best_block_height, logger, send_payment_along_path);
-                               log_info!(logger, "Result retrying payment id {}: {:?}", log_bytes!(payment_id.0), retry_res);
-                               Ok(())
-                       },
-                       Err(PaymentSendFailure::PartialFailure { failed_paths_retry: None, .. }) => {
-                               // This may happen if we send a payment and some paths fail, but only due to a temporary
-                               // monitor failure or the like, implying they're really in-flight, but we haven't sent the
-                               // initial HTLC-Add messages yet.
-                               Ok(())
-                       },
-                       res => res,
+                       Some(&first_hops.iter().collect::<Vec<_>>()), &inflight_htlcs()
+               ).map_err(|_| RetryableSendFailure::RouteNotFound)?;
+
+               let onion_session_privs = self.add_new_pending_payment(payment_hash, *payment_secret,
+                       payment_id, keysend_preimage, &route, Some(retry_strategy),
+                       Some(route_params.payment_params.clone()), entropy_source, best_block_height)
+                       .map_err(|_| RetryableSendFailure::DuplicatePayment)?;
+
+               let res = self.pay_route_internal(&route, payment_hash, payment_secret, None, payment_id, None,
+                       onion_session_privs, node_signer, best_block_height, &send_payment_along_path);
+               log_info!(logger, "Result sending payment with id {}: {:?}", log_bytes!(payment_id.0), res);
+               if let Err(e) = res {
+                       self.handle_pay_route_err(e, payment_id, payment_hash, route, route_params, router, first_hops, &inflight_htlcs, entropy_source, node_signer, best_block_height, logger, pending_events, &send_payment_along_path);
                }
+               Ok(())
        }
 
-       pub(super) fn retry_payment_with_route<ES: Deref, NS: Deref, F>(
-               &self, route: &Route, payment_id: PaymentId, entropy_source: &ES, node_signer: &NS, best_block_height: u32,
-               send_payment_along_path: F
-       ) -> Result<(), PaymentSendFailure>
+       fn retry_payment_internal<R: Deref, NS: Deref, ES: Deref, IH, SP, L: Deref>(
+               &self, payment_id: PaymentId, route_params: RouteParameters, router: &R,
+               first_hops: Vec<ChannelDetails>, inflight_htlcs: &IH, entropy_source: &ES, node_signer: &NS,
+               best_block_height: u32, logger: &L, pending_events: &Mutex<Vec<events::Event>>,
+               send_payment_along_path: &SP,
+       )
        where
+               R::Target: Router,
                ES::Target: EntropySource,
                NS::Target: NodeSigner,
-               F: Fn(&Vec<RouteHop>, &Option<PaymentParameters>, &PaymentHash, &Option<PaymentSecret>, u64,
-                  u32, PaymentId, &Option<PaymentPreimage>, [u8; 32]) -> Result<(), APIError>
+               L::Target: Logger,
+               IH: Fn() -> InFlightHtlcs,
+               SP: Fn(&Vec<RouteHop>, &Option<PaymentParameters>, &PaymentHash, &Option<PaymentSecret>, u64,
+                   u32, PaymentId, &Option<PaymentPreimage>, [u8; 32]) -> Result<(), APIError>
        {
-               const RETRY_OVERFLOW_PERCENTAGE: u64 = 10;
+               #[cfg(feature = "std")] {
+                       if has_expired(&route_params) {
+                               log_error!(logger, "Payment params expired on retry, abandoning payment {}", log_bytes!(payment_id.0));
+                               self.abandon_payment(payment_id, pending_events);
+                               return
+                       }
+               }
+
+               let route = match router.find_route(
+                       &node_signer.get_node_id(Recipient::Node).unwrap(), &route_params,
+                       Some(&first_hops.iter().collect::<Vec<_>>()), &inflight_htlcs()
+               ) {
+                       Ok(route) => route,
+                       Err(e) => {
+                               log_error!(logger, "Failed to find a route on retry, abandoning payment {}: {:#?}", log_bytes!(payment_id.0), e);
+                               self.abandon_payment(payment_id, pending_events);
+                               return
+                       }
+               };
                for path in route.paths.iter() {
                        if path.len() == 0 {
-                               return Err(PaymentSendFailure::ParameterError(APIError::APIMisuseError {
-                                       err: "length-0 path in route".to_string()
-                               }))
+                               log_error!(logger, "length-0 path in route");
+                               self.abandon_payment(payment_id, pending_events);
+                               return
                        }
                }
 
+               const RETRY_OVERFLOW_PERCENTAGE: u64 = 10;
                let mut onion_session_privs = Vec::with_capacity(route.paths.len());
                for _ in 0..route.paths.len() {
                        onion_session_privs.push(entropy_source.get_secure_random_bytes());
                }
 
+               macro_rules! abandon_with_entry {
+                       ($payment_id: expr, $payment_hash: expr, $payment: expr, $pending_events: expr) => {
+                               if $payment.get_mut().mark_abandoned().is_ok() && $payment.get().remaining_parts() == 0 {
+                                       $pending_events.lock().unwrap().push(events::Event::PaymentFailed {
+                                               payment_id: $payment_id,
+                                               payment_hash: $payment_hash,
+                                       });
+                                       $payment.remove();
+                               }
+                       }
+               }
                let (total_msat, payment_hash, payment_secret, keysend_preimage) = {
                        let mut outbounds = self.pending_outbound_payments.lock().unwrap();
-                       match outbounds.get_mut(&payment_id) {
-                               Some(payment) => {
-                                       let res = match payment {
+                       match outbounds.entry(payment_id) {
+                               hash_map::Entry::Occupied(mut payment) => {
+                                       let res = match payment.get() {
                                                PendingOutboundPayment::Retryable {
                                                        total_msat, payment_hash, keysend_preimage, payment_secret, pending_amt_msat, ..
                                                } => {
                                                        let retry_amt_msat: u64 = route.paths.iter().map(|path| path.last().unwrap().fee_msat).sum();
                                                        if retry_amt_msat + *pending_amt_msat > *total_msat * (100 + RETRY_OVERFLOW_PERCENTAGE) / 100 {
-                                                               return Err(PaymentSendFailure::ParameterError(APIError::APIMisuseError {
-                                                                       err: format!("retry_amt_msat of {} will put pending_amt_msat (currently: {}) more than 10% over total_payment_amt_msat of {}", retry_amt_msat, pending_amt_msat, total_msat).to_string()
-                                                               }))
+                                                               log_error!(logger, "retry_amt_msat of {} will put pending_amt_msat (currently: {}) more than 10% over total_payment_amt_msat of {}", retry_amt_msat, pending_amt_msat, total_msat);
+                                                               let payment_hash = *payment_hash;
+                                                               abandon_with_entry!(payment_id, payment_hash, payment, pending_events);
+                                                               return
                                                        }
                                                        (*total_msat, *payment_hash, *payment_secret, *keysend_preimage)
                                                },
                                                PendingOutboundPayment::Legacy { .. } => {
-                                                       return Err(PaymentSendFailure::ParameterError(APIError::APIMisuseError {
-                                                               err: "Unable to retry payments that were initially sent on LDK versions prior to 0.0.102".to_string()
-                                                       }))
+                                                       log_error!(logger, "Unable to retry payments that were initially sent on LDK versions prior to 0.0.102");
+                                                       return
                                                },
                                                PendingOutboundPayment::Fulfilled { .. } => {
-                                                       return Err(PaymentSendFailure::ParameterError(APIError::APIMisuseError {
-                                                               err: "Payment already completed".to_owned()
-                                                       }));
+                                                       log_error!(logger, "Payment already completed");
+                                                       return
                                                },
                                                PendingOutboundPayment::Abandoned { .. } => {
-                                                       return Err(PaymentSendFailure::ParameterError(APIError::APIMisuseError {
-                                                               err: "Payment already abandoned (with some HTLCs still pending)".to_owned()
-                                                       }));
+                                                       log_error!(logger, "Payment already abandoned (with some HTLCs still pending)");
+                                                       return
                                                },
                                        };
-                                       if !payment.is_retryable_now() {
-                                               return Err(PaymentSendFailure::ParameterError(APIError::APIMisuseError {
-                                                       err: format!("Retries exhausted for payment id {}", log_bytes!(payment_id.0)),
-                                               }))
+                                       if !payment.get().is_retryable_now() {
+                                               log_error!(logger, "Retries exhausted for payment id {}", log_bytes!(payment_id.0));
+                                               abandon_with_entry!(payment_id, res.1, payment, pending_events);
+                                               return
                                        }
-                                       payment.increment_attempts();
+                                       payment.get_mut().increment_attempts();
                                        for (path, session_priv_bytes) in route.paths.iter().zip(onion_session_privs.iter()) {
-                                               assert!(payment.insert(*session_priv_bytes, path));
+                                               assert!(payment.get_mut().insert(*session_priv_bytes, path));
                                        }
                                        res
                                },
-                               None =>
-                                       return Err(PaymentSendFailure::ParameterError(APIError::APIMisuseError {
-                                               err: format!("Payment with ID {} not found", log_bytes!(payment_id.0)),
-                                       })),
+                               hash_map::Entry::Vacant(_) => {
+                                       log_error!(logger, "Payment with ID {} not found", log_bytes!(payment_id.0));
+                                       return
+                               }
                        }
                };
-               self.pay_route_internal(route, payment_hash, &payment_secret, keysend_preimage, payment_id, Some(total_msat), onion_session_privs, node_signer, best_block_height, &send_payment_along_path)
+               let res = self.pay_route_internal(&route, payment_hash, &payment_secret, keysend_preimage,
+                       payment_id, Some(total_msat), onion_session_privs, node_signer, best_block_height,
+                       &send_payment_along_path);
+               log_info!(logger, "Result retrying payment id {}: {:?}", log_bytes!(payment_id.0), res);
+               if let Err(e) = res {
+                       self.handle_pay_route_err(e, payment_id, payment_hash, route, route_params, router, first_hops, inflight_htlcs, entropy_source, node_signer, best_block_height, logger, pending_events, send_payment_along_path);
+               }
+       }
+
+       fn handle_pay_route_err<R: Deref, NS: Deref, ES: Deref, IH, SP, L: Deref>(
+               &self, err: PaymentSendFailure, payment_id: PaymentId, payment_hash: PaymentHash, route: Route,
+               mut route_params: RouteParameters, router: &R, first_hops: Vec<ChannelDetails>,
+               inflight_htlcs: &IH, entropy_source: &ES, node_signer: &NS, best_block_height: u32, logger: &L,
+               pending_events: &Mutex<Vec<events::Event>>, send_payment_along_path: &SP,
+       )
+       where
+               R::Target: Router,
+               ES::Target: EntropySource,
+               NS::Target: NodeSigner,
+               L::Target: Logger,
+               IH: Fn() -> InFlightHtlcs,
+               SP: Fn(&Vec<RouteHop>, &Option<PaymentParameters>, &PaymentHash, &Option<PaymentSecret>, u64,
+                   u32, PaymentId, &Option<PaymentPreimage>, [u8; 32]) -> Result<(), APIError>
+       {
+               match err {
+                       PaymentSendFailure::AllFailedResendSafe(errs) => {
+                               Self::push_path_failed_evs_and_scids(payment_id, payment_hash, &mut route_params, route.paths, errs.into_iter().map(|e| Err(e)), pending_events);
+                               self.retry_payment_internal(payment_id, route_params, router, first_hops, inflight_htlcs, entropy_source, node_signer, best_block_height, logger, pending_events, send_payment_along_path);
+                       },
+                       PaymentSendFailure::PartialFailure { failed_paths_retry: Some(mut retry), results, .. } => {
+                               Self::push_path_failed_evs_and_scids(payment_id, payment_hash, &mut retry, route.paths, results.into_iter(), pending_events);
+                               // Some paths were sent, even if we failed to send the full MPP value our recipient may
+                               // misbehave and claim the funds, at which point we have to consider the payment sent, so
+                               // return `Ok()` here, ignoring any retry errors.
+                               self.retry_payment_internal(payment_id, retry, router, first_hops, inflight_htlcs, entropy_source, node_signer, best_block_height, logger, pending_events, send_payment_along_path);
+                       },
+                       PaymentSendFailure::PartialFailure { failed_paths_retry: None, .. } => {
+                               // This may happen if we send a payment and some paths fail, but only due to a temporary
+                               // monitor failure or the like, implying they're really in-flight, but we haven't sent the
+                               // initial HTLC-Add messages yet.
+                       },
+                       PaymentSendFailure::PathParameterError(results) => {
+                               Self::push_path_failed_evs_and_scids(payment_id, payment_hash, &mut route_params, route.paths, results.into_iter(), pending_events);
+                               self.abandon_payment(payment_id, pending_events);
+                       },
+                       PaymentSendFailure::ParameterError(e) => {
+                               log_error!(logger, "Failed to send to route due to parameter error: {:?}. Your router is buggy", e);
+                               self.abandon_payment(payment_id, pending_events);
+                       },
+                       PaymentSendFailure::DuplicatePayment => debug_assert!(false), // unreachable
+               }
+       }
+
+       fn push_path_failed_evs_and_scids<I: ExactSizeIterator + Iterator<Item = Result<(), APIError>>>(
+               payment_id: PaymentId, payment_hash: PaymentHash, route_params: &mut RouteParameters,
+               paths: Vec<Vec<RouteHop>>, path_results: I, pending_events: &Mutex<Vec<events::Event>>
+       ) {
+               let mut events = pending_events.lock().unwrap();
+               debug_assert_eq!(paths.len(), path_results.len());
+               for (path, path_res) in paths.into_iter().zip(path_results) {
+                       if let Err(e) = path_res {
+                               let failed_scid = if let APIError::InvalidRoute { .. } = e {
+                                       None
+                               } else {
+                                       let scid = path[0].short_channel_id;
+                                       route_params.payment_params.previously_failed_channels.push(scid);
+                                       Some(scid)
+                               };
+                               events.push(events::Event::PaymentPathFailed {
+                                       payment_id: Some(payment_id),
+                                       payment_hash,
+                                       payment_failed_permanently: false,
+                                       network_update: None,
+                                       all_paths_failed: false,
+                                       path,
+                                       short_channel_id: failed_scid,
+                                       retry: None,
+                                       #[cfg(test)]
+                                       error_code: None,
+                                       #[cfg(test)]
+                                       error_data: None,
+                               });
+                       }
+               }
        }
 
        pub(super) fn send_probe<ES: Deref, NS: Deref, F>(
@@ -1240,13 +1356,13 @@ mod tests {
        use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
 
        use crate::ln::PaymentHash;
-       use crate::ln::channelmanager::{PaymentId, PaymentSendFailure};
+       use crate::ln::channelmanager::PaymentId;
        use crate::ln::msgs::{ErrorAction, LightningError};
-       use crate::ln::outbound_payment::{OutboundPayments, Retry};
+       use crate::ln::outbound_payment::{OutboundPayments, Retry, RetryableSendFailure};
        use crate::routing::gossip::NetworkGraph;
        use crate::routing::router::{InFlightHtlcs, PaymentParameters, Route, RouteParameters};
        use crate::sync::{Arc, Mutex};
-       use crate::util::errors::APIError;
+       use crate::util::events::Event;
        use crate::util::test_utils;
 
        #[test]
@@ -1275,19 +1391,25 @@ mod tests {
                        final_value_msat: 0,
                        final_cltv_expiry_delta: 0,
                };
-               let err = if on_retry {
-                       outbound_payments.pay_internal(
-                               PaymentId([0; 32]), None, expired_route_params, &&router, vec![], &|| InFlightHtlcs::new(),
-                               &&keys_manager, &&keys_manager, 0, &&logger, &|_, _, _, _, _, _, _, _, _| Ok(())).unwrap_err()
+               let pending_events = Mutex::new(Vec::new());
+               if on_retry {
+                       outbound_payments.add_new_pending_payment(PaymentHash([0; 32]), None, PaymentId([0; 32]), None,
+                       &Route { paths: vec![], payment_params: None }, Some(Retry::Attempts(1)),
+                       Some(expired_route_params.payment_params.clone()), &&keys_manager, 0).unwrap();
+                       outbound_payments.retry_payment_internal(
+                               PaymentId([0; 32]), expired_route_params, &&router, vec![], &|| InFlightHtlcs::new(),
+                               &&keys_manager, &&keys_manager, 0, &&logger, &pending_events,
+                               &|_, _, _, _, _, _, _, _, _| Ok(()));
+                       let events = pending_events.lock().unwrap();
+                       assert_eq!(events.len(), 1);
+                       if let Event::PaymentFailed { .. } = events[0] { } else { panic!("Unexpected event"); }
                } else {
-                       outbound_payments.send_payment(
+                       let err = outbound_payments.send_payment(
                                PaymentHash([0; 32]), &None, PaymentId([0; 32]), Retry::Attempts(0), expired_route_params,
                                &&router, vec![], || InFlightHtlcs::new(), &&keys_manager, &&keys_manager, 0, &&logger,
-                               |_, _, _, _, _, _, _, _, _| Ok(())).unwrap_err()
-               };
-               if let PaymentSendFailure::ParameterError(APIError::APIMisuseError { err }) = err {
-                       assert!(err.contains("Invoice expired"));
-               } else { panic!("Unexpected error"); }
+                               &pending_events, |_, _, _, _, _, _, _, _, _| Ok(())).unwrap_err();
+                       if let RetryableSendFailure::PaymentExpired = err { } else { panic!("Unexpected error"); }
+               }
        }
 
        #[test]
@@ -1314,21 +1436,25 @@ mod tests {
                router.expect_find_route(route_params.clone(),
                        Err(LightningError { err: String::new(), action: ErrorAction::IgnoreError }));
 
-               let err = if on_retry {
+               let pending_events = Mutex::new(Vec::new());
+               if on_retry {
                        outbound_payments.add_new_pending_payment(PaymentHash([0; 32]), None, PaymentId([0; 32]), None,
                                &Route { paths: vec![], payment_params: None }, Some(Retry::Attempts(1)),
                                Some(route_params.payment_params.clone()), &&keys_manager, 0).unwrap();
-                       outbound_payments.pay_internal(
-                               PaymentId([0; 32]), None, route_params, &&router, vec![], &|| InFlightHtlcs::new(),
-                               &&keys_manager, &&keys_manager, 0, &&logger, &|_, _, _, _, _, _, _, _, _| Ok(())).unwrap_err()
+                       outbound_payments.retry_payment_internal(
+                               PaymentId([0; 32]), route_params, &&router, vec![], &|| InFlightHtlcs::new(),
+                               &&keys_manager, &&keys_manager, 0, &&logger, &pending_events,
+                               &|_, _, _, _, _, _, _, _, _| Ok(()));
+                       let events = pending_events.lock().unwrap();
+                       assert_eq!(events.len(), 1);
+                       if let Event::PaymentFailed { .. } = events[0] { } else { panic!("Unexpected event"); }
                } else {
-                       outbound_payments.send_payment(
+                       let err = outbound_payments.send_payment(
                                PaymentHash([0; 32]), &None, PaymentId([0; 32]), Retry::Attempts(0), route_params,
                                &&router, vec![], || InFlightHtlcs::new(), &&keys_manager, &&keys_manager, 0, &&logger,
-                               |_, _, _, _, _, _, _, _, _| Ok(())).unwrap_err()
-               };
-               if let PaymentSendFailure::ParameterError(APIError::APIMisuseError { err }) = err {
-                       assert!(err.contains("Failed to find a route"));
-               } else { panic!("Unexpected error"); }
+                               &pending_events, |_, _, _, _, _, _, _, _, _| Ok(())).unwrap_err();
+                       if let RetryableSendFailure::RouteNotFound = err {
+                       } else { panic!("Unexpected error"); }
+               }
        }
 }