Merge pull request #1972 from jkczyz/2023-01-bolt12-spec-updates
[rust-lightning] / lightning / src / ln / outbound_payment.rs
index 2f520fa71956577d14a2ba475e0d02a883b27304..8867b2e96ae14c3e75bb960d5dd9fa97ed10d746 100644 (file)
@@ -13,18 +13,24 @@ use bitcoin::hashes::Hash;
 use bitcoin::hashes::sha256::Hash as Sha256;
 use bitcoin::secp256k1::{self, Secp256k1, SecretKey};
 
-use crate::chain::keysinterface::{KeysInterface, Recipient};
+use crate::chain::keysinterface::{EntropySource, NodeSigner, Recipient};
 use crate::ln::{PaymentHash, PaymentPreimage, PaymentSecret};
-use crate::ln::channelmanager::{HTLCSource, IDEMPOTENCY_TIMEOUT_TICKS, PaymentId};
+use crate::ln::channelmanager::{ChannelDetails, HTLCSource, IDEMPOTENCY_TIMEOUT_TICKS, MIN_HTLC_RELAY_HOLDING_CELL_MILLIS, PaymentId};
 use crate::ln::msgs::DecodeError;
 use crate::ln::onion_utils::HTLCFailReason;
-use crate::routing::router::{PaymentParameters, Route, RouteHop, RouteParameters, RoutePath};
+use crate::routing::router::{InFlightHtlcs, PaymentParameters, Route, RouteHop, RouteParameters, RoutePath, Router};
 use crate::util::errors::APIError;
 use crate::util::events;
 use crate::util::logger::Logger;
+use crate::util::time::Time;
+#[cfg(all(not(feature = "no-std"), test))]
+use crate::util::time::tests::SinceEpoch;
 
 use core::cmp;
+use core::fmt::{self, Display, Formatter};
 use core::ops::Deref;
+use core::time::Duration;
+
 use crate::prelude::*;
 use crate::sync::Mutex;
 
@@ -35,6 +41,9 @@ pub(crate) enum PendingOutboundPayment {
                session_privs: HashSet<[u8; 32]>,
        },
        Retryable {
+               retry_strategy: Retry,
+               attempts: PaymentAttempts,
+               route_params: Option<RouteParameters>,
                session_privs: HashSet<[u8; 32]>,
                payment_hash: PaymentHash,
                payment_secret: Option<PaymentSecret>,
@@ -60,7 +69,7 @@ pub(crate) enum PendingOutboundPayment {
        /// `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
+       /// (1) <https://github.com/lightningdevkit/rust-lightning/issues/1164>
        Abandoned {
                session_privs: HashSet<[u8; 32]>,
                payment_hash: PaymentHash,
@@ -68,6 +77,22 @@ pub(crate) enum PendingOutboundPayment {
 }
 
 impl PendingOutboundPayment {
+       fn increment_attempts(&mut self) {
+               if let PendingOutboundPayment::Retryable { attempts, .. } = self {
+                       attempts.count += 1;
+               }
+       }
+       fn is_retryable_now(&self) -> bool {
+               if let PendingOutboundPayment::Retryable { retry_strategy, attempts, .. } = self {
+                       return retry_strategy.is_retryable_now(&attempts)
+               }
+               false
+       }
+       pub fn insert_previously_failed_scid(&mut self, scid: u64) {
+               if let PendingOutboundPayment::Retryable { route_params: Some(params), .. } = self {
+                       params.payment_params.previously_failed_channels.push(scid);
+               }
+       }
        pub(super) fn is_fulfilled(&self) -> bool {
                match self {
                        PendingOutboundPayment::Fulfilled { .. } => true,
@@ -80,14 +105,14 @@ impl PendingOutboundPayment {
                        _ => false,
                }
        }
-       pub(super) fn get_pending_fee_msat(&self) -> Option<u64> {
+       fn get_pending_fee_msat(&self) -> Option<u64> {
                match self {
                        PendingOutboundPayment::Retryable { pending_fee_msat, .. } => pending_fee_msat.clone(),
                        _ => None,
                }
        }
 
-       pub(super) fn payment_hash(&self) -> Option<PaymentHash> {
+       fn payment_hash(&self) -> Option<PaymentHash> {
                match self {
                        PendingOutboundPayment::Legacy { .. } => None,
                        PendingOutboundPayment::Retryable { payment_hash, .. } => Some(*payment_hash),
@@ -96,7 +121,7 @@ impl PendingOutboundPayment {
                }
        }
 
-       pub(super) fn mark_fulfilled(&mut self) {
+       fn mark_fulfilled(&mut self) {
                let mut session_privs = HashSet::new();
                core::mem::swap(&mut session_privs, match self {
                        PendingOutboundPayment::Legacy { session_privs } |
@@ -109,7 +134,7 @@ impl PendingOutboundPayment {
                *self = PendingOutboundPayment::Fulfilled { session_privs, payment_hash, timer_ticks_without_htlcs: 0 };
        }
 
-       pub(super) fn mark_abandoned(&mut self) -> Result<(), ()> {
+       fn mark_abandoned(&mut self) -> Result<(), ()> {
                let mut session_privs = HashSet::new();
                let our_payment_hash;
                core::mem::swap(&mut session_privs, match self {
@@ -127,7 +152,7 @@ impl PendingOutboundPayment {
        }
 
        /// panics if path is None and !self.is_fulfilled
-       pub(super) fn remove(&mut self, session_priv: &[u8; 32], path: Option<&Vec<RouteHop>>) -> bool {
+       fn remove(&mut self, session_priv: &[u8; 32], path: Option<&Vec<RouteHop>>) -> bool {
                let remove_res = match self {
                        PendingOutboundPayment::Legacy { session_privs } |
                                PendingOutboundPayment::Retryable { session_privs, .. } |
@@ -182,6 +207,88 @@ impl PendingOutboundPayment {
        }
 }
 
+/// Strategies available to retry payment path failures.
+#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
+pub enum Retry {
+       /// Max number of attempts to retry payment.
+       ///
+       /// Note that this is the number of *path* failures, not full payment retries. For multi-path
+       /// payments, if this is less than the total number of paths, we will never even retry all of the
+       /// payment's paths.
+       Attempts(usize),
+       #[cfg(not(feature = "no-std"))]
+       /// Time elapsed before abandoning retries for a payment.
+       Timeout(core::time::Duration),
+}
+
+impl Retry {
+       pub(crate) fn is_retryable_now(&self, attempts: &PaymentAttempts) -> bool {
+               match (self, attempts) {
+                       (Retry::Attempts(max_retry_count), PaymentAttempts { count, .. }) => {
+                               max_retry_count > count
+                       },
+                       #[cfg(all(not(feature = "no-std"), not(test)))]
+                       (Retry::Timeout(max_duration), PaymentAttempts { first_attempted_at, .. }) =>
+                               *max_duration >= std::time::Instant::now().duration_since(*first_attempted_at),
+                       #[cfg(all(not(feature = "no-std"), test))]
+                       (Retry::Timeout(max_duration), PaymentAttempts { first_attempted_at, .. }) =>
+                               *max_duration >= SinceEpoch::now().duration_since(*first_attempted_at),
+               }
+       }
+}
+
+#[cfg(feature = "std")]
+pub(super) fn has_expired(route_params: &RouteParameters) -> bool {
+       if let Some(expiry_time) = route_params.payment_params.expiry_time {
+               if let Ok(elapsed) = std::time::SystemTime::UNIX_EPOCH.elapsed() {
+                       return elapsed > core::time::Duration::from_secs(expiry_time)
+               }
+       }
+       false
+}
+
+pub(crate) type PaymentAttempts = PaymentAttemptsUsingTime<ConfiguredTime>;
+
+/// Storing minimal payment attempts information required for determining if a outbound payment can
+/// be retried.
+pub(crate) struct PaymentAttemptsUsingTime<T: Time> {
+       /// This count will be incremented only after the result of the attempt is known. When it's 0,
+       /// it means the result of the first attempt is not known yet.
+       pub(crate) count: usize,
+       /// This field is only used when retry is `Retry::Timeout` which is only build with feature std
+       first_attempted_at: T
+}
+
+#[cfg(not(any(feature = "no-std", test)))]
+type ConfiguredTime = std::time::Instant;
+#[cfg(feature = "no-std")]
+type ConfiguredTime = crate::util::time::Eternity;
+#[cfg(all(not(feature = "no-std"), test))]
+type ConfiguredTime = SinceEpoch;
+
+impl<T: Time> PaymentAttemptsUsingTime<T> {
+       pub(crate) fn new() -> Self {
+               PaymentAttemptsUsingTime {
+                       count: 0,
+                       first_attempted_at: T::now()
+               }
+       }
+}
+
+impl<T: Time> Display for PaymentAttemptsUsingTime<T> {
+       fn fmt(&self, f: &mut Formatter) -> Result<(), fmt::Error> {
+               #[cfg(feature = "no-std")]
+               return write!(f, "attempts: {}", self.count);
+               #[cfg(not(feature = "no-std"))]
+               return write!(
+                       f,
+                       "attempts: {}, duration: {}s",
+                       self.count,
+                       T::now().duration_since(self.first_attempted_at).as_secs()
+               );
+       }
+}
+
 /// 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.
@@ -271,47 +378,185 @@ impl OutboundPayments {
                }
        }
 
-       pub(super) fn send_payment<K: Deref, F>(
+       pub(super) fn send_payment<R: Deref, ES: Deref, NS: Deref, F>(
+               &self, payment_hash: PaymentHash, payment_secret: &Option<PaymentSecret>, payment_id: PaymentId,
+               retry_strategy: Retry, route_params: RouteParameters, router: &R,
+               first_hops: Vec<ChannelDetails>, inflight_htlcs: InFlightHtlcs, entropy_source: &ES,
+               node_signer: &NS, best_block_height: u32, send_payment_along_path: F
+       ) -> Result<(), PaymentSendFailure>
+       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>,
+       {
+               self.pay_internal(payment_id, Some((payment_hash, payment_secret, retry_strategy)),
+                       route_params, router, first_hops, inflight_htlcs, entropy_source, node_signer,
+                       best_block_height, &send_payment_along_path)
+                       .map_err(|e| { self.remove_outbound_if_all_failed(payment_id, &e); e })
+       }
+
+       pub(super) fn send_payment_with_route<ES: Deref, NS: Deref, F>(
                &self, route: &Route, payment_hash: PaymentHash, payment_secret: &Option<PaymentSecret>,
-               payment_id: PaymentId, keys_manager: &K, best_block_height: u32, send_payment_along_path: F
+               payment_id: PaymentId, entropy_source: &ES, node_signer: &NS, best_block_height: u32,
+               send_payment_along_path: F
        ) -> Result<(), PaymentSendFailure>
        where
-               K::Target: KeysInterface,
+               ES::Target: EntropySource,
+               NS::Target: NodeSigner,
                F: Fn(&Vec<RouteHop>, &Option<PaymentParameters>, &PaymentHash, &Option<PaymentSecret>, u64,
                   u32, PaymentId, &Option<PaymentPreimage>, [u8; 32]) -> Result<(), APIError>
        {
-               let onion_session_privs = self.add_new_pending_payment(payment_hash, *payment_secret, payment_id, route, keys_manager, best_block_height)?;
-               self.send_payment_internal(route, payment_hash, payment_secret, None, payment_id, None, onion_session_privs, keys_manager, best_block_height, send_payment_along_path)
+               let onion_session_privs = self.add_new_pending_payment(payment_hash, *payment_secret, payment_id, route, Retry::Attempts(0), None, 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)
+                       .map_err(|e| { self.remove_outbound_if_all_failed(payment_id, &e); e })
        }
 
-       pub(super) fn send_spontaneous_payment<K: Deref, F>(
+       pub(super) fn send_spontaneous_payment<ES: Deref, NS: Deref, F>(
                &self, route: &Route, payment_preimage: Option<PaymentPreimage>, payment_id: PaymentId,
-               keys_manager: &K, best_block_height: u32, send_payment_along_path: F
+               entropy_source: &ES, node_signer: &NS, best_block_height: u32, send_payment_along_path: F
        ) -> Result<PaymentHash, PaymentSendFailure>
        where
-               K::Target: KeysInterface,
+               ES::Target: EntropySource,
+               NS::Target: NodeSigner,
                F: Fn(&Vec<RouteHop>, &Option<PaymentParameters>, &PaymentHash, &Option<PaymentSecret>, u64,
                   u32, PaymentId, &Option<PaymentPreimage>, [u8; 32]) -> Result<(), APIError>
        {
                let preimage = match payment_preimage {
                        Some(p) => p,
-                       None => PaymentPreimage(keys_manager.get_secure_random_bytes()),
+                       None => PaymentPreimage(entropy_source.get_secure_random_bytes()),
                };
                let payment_hash = PaymentHash(Sha256::hash(&preimage.0).into_inner());
-               let onion_session_privs = self.add_new_pending_payment(payment_hash, None, payment_id, &route, keys_manager, best_block_height)?;
+               let onion_session_privs = self.add_new_pending_payment(payment_hash, None, payment_id, &route, Retry::Attempts(0), None, entropy_source, best_block_height)?;
 
-               match self.send_payment_internal(route, payment_hash, &None, Some(preimage), payment_id, None, onion_session_privs, keys_manager, best_block_height, send_payment_along_path) {
+               match self.pay_route_internal(route, payment_hash, &None, Some(preimage), payment_id, None, onion_session_privs, node_signer, best_block_height, &send_payment_along_path) {
                        Ok(()) => Ok(payment_hash),
-                       Err(e) => Err(e)
+                       Err(e) => {
+                               self.remove_outbound_if_all_failed(payment_id, &e);
+                               Err(e)
+                       }
+               }
+       }
+
+       pub(super) fn check_retry_payments<R: Deref, ES: Deref, NS: Deref, SP, IH, FH, L: Deref>(
+               &self, router: &R, first_hops: FH, inflight_htlcs: IH, entropy_source: &ES, node_signer: &NS,
+               best_block_height: u32, logger: &L, send_payment_along_path: SP,
+       )
+       where
+               R::Target: Router,
+               ES::Target: EntropySource,
+               NS::Target: NodeSigner,
+               SP: Fn(&Vec<RouteHop>, &Option<PaymentParameters>, &PaymentHash, &Option<PaymentSecret>, u64,
+                  u32, PaymentId, &Option<PaymentPreimage>, [u8; 32]) -> Result<(), APIError>,
+               IH: Fn() -> InFlightHtlcs,
+               FH: Fn() -> Vec<ChannelDetails>,
+               L::Target: Logger,
+       {
+               loop {
+                       let mut outbounds = self.pending_outbound_payments.lock().unwrap();
+                       let mut retry_id_route_params = None;
+                       for (pmt_id, pmt) in outbounds.iter_mut() {
+                               if pmt.is_retryable_now() {
+                                       if let PendingOutboundPayment::Retryable { pending_amt_msat, total_msat, route_params: Some(params), .. } = pmt {
+                                               if pending_amt_msat < total_msat {
+                                                       retry_id_route_params = Some((*pmt_id, params.clone()));
+                                                       pmt.increment_attempts();
+                                                       break
+                                               }
+                                       }
+                               }
+                       }
+                       if let Some((payment_id, route_params)) = retry_id_route_params {
+                               core::mem::drop(outbounds);
+                               if let Err(e) = self.pay_internal(payment_id, None, route_params, router, first_hops(), inflight_htlcs(), entropy_source, node_signer, best_block_height, &send_payment_along_path) {
+                                       log_trace!(logger, "Errored retrying payment: {:?}", e);
+                               }
+                       } else { break }
+               }
+       }
+
+       fn pay_internal<R: Deref, NS: Deref, ES: Deref, F>(
+               &self, payment_id: PaymentId,
+               initial_send_info: Option<(PaymentHash, &Option<PaymentSecret>, Retry)>,
+               route_params: RouteParameters, router: &R, first_hops: Vec<ChannelDetails>,
+               inflight_htlcs: InFlightHtlcs, entropy_source: &ES, node_signer: &NS, best_block_height: u32,
+               send_payment_along_path: &F
+       ) -> Result<(), PaymentSendFailure>
+       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>
+       {
+               #[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)),
+                               }))
+                       }
+               }
+
+               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, retry_strategy)) = initial_send_info {
+                       let onion_session_privs = self.add_new_pending_payment(payment_hash, *payment_secret, payment_id, &route, retry_strategy, Some(route_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 mut outbounds = self.pending_outbound_payments.lock().unwrap();
+                               if let Some(payment) = outbounds.get_mut(&payment_id) {
+                                       let retryable = payment.is_retryable_now();
+                                       if retryable {
+                                               payment.increment_attempts();
+                                       } else { return res }
+                               } else { return res }
+                               core::mem::drop(outbounds);
+                               self.pay_internal(payment_id, None, route_params, router, first_hops, inflight_htlcs, entropy_source, node_signer, best_block_height, send_payment_along_path)
+                       },
+                       Err(PaymentSendFailure::PartialFailure { failed_paths_retry: Some(retry), results, .. }) => {
+                               let mut outbounds = self.pending_outbound_payments.lock().unwrap();
+                               if let Some(payment) = outbounds.get_mut(&payment_id) {
+                                       let retryable = payment.is_retryable_now();
+                                       if retryable {
+                                               payment.increment_attempts();
+                                       } else { return Err(PaymentSendFailure::PartialFailure { failed_paths_retry: Some(retry), results, payment_id }) }
+                               } else { return Err(PaymentSendFailure::PartialFailure { failed_paths_retry: Some(retry), results, payment_id }) }
+                               core::mem::drop(outbounds);
+
+                               // 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 _ = self.pay_internal(payment_id, None, retry, router, first_hops, inflight_htlcs, entropy_source, node_signer, best_block_height, send_payment_along_path);
+                               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,
                }
        }
 
-       pub(super) fn retry_payment<K: Deref, F>(
-               &self, route: &Route, payment_id: PaymentId, keys_manager: &K, best_block_height: u32,
+       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>
        where
-               K::Target: KeysInterface,
+               ES::Target: EntropySource,
+               NS::Target: NodeSigner,
                F: Fn(&Vec<RouteHop>, &Option<PaymentParameters>, &PaymentHash, &Option<PaymentSecret>, u64,
                   u32, PaymentId, &Option<PaymentPreimage>, [u8; 32]) -> Result<(), APIError>
        {
@@ -326,7 +571,7 @@ impl OutboundPayments {
 
                let mut onion_session_privs = Vec::with_capacity(route.paths.len());
                for _ in 0..route.paths.len() {
-                       onion_session_privs.push(keys_manager.get_secure_random_bytes());
+                       onion_session_privs.push(entropy_source.get_secure_random_bytes());
                }
 
                let (total_msat, payment_hash, payment_secret) = {
@@ -372,19 +617,20 @@ impl OutboundPayments {
                                        })),
                        }
                };
-               self.send_payment_internal(route, payment_hash, &payment_secret, None, payment_id, Some(total_msat), onion_session_privs, keys_manager, best_block_height, send_payment_along_path)
+               self.pay_route_internal(route, payment_hash, &payment_secret, None, payment_id, Some(total_msat), onion_session_privs, node_signer, best_block_height, &send_payment_along_path)
        }
 
-       pub(super) fn send_probe<K: Deref, F>(
-               &self, hops: Vec<RouteHop>, probing_cookie_secret: [u8; 32], keys_manager: &K,
-               best_block_height: u32, send_payment_along_path: F
+       pub(super) fn send_probe<ES: Deref, NS: Deref, F>(
+               &self, hops: Vec<RouteHop>, probing_cookie_secret: [u8; 32], entropy_source: &ES,
+               node_signer: &NS, best_block_height: u32, send_payment_along_path: F
        ) -> Result<(PaymentHash, PaymentId), PaymentSendFailure>
        where
-               K::Target: KeysInterface,
+               ES::Target: EntropySource,
+               NS::Target: NodeSigner,
                F: Fn(&Vec<RouteHop>, &Option<PaymentParameters>, &PaymentHash, &Option<PaymentSecret>, u64,
                   u32, PaymentId, &Option<PaymentPreimage>, [u8; 32]) -> Result<(), APIError>
        {
-               let payment_id = PaymentId(keys_manager.get_secure_random_bytes());
+               let payment_id = PaymentId(entropy_source.get_secure_random_bytes());
 
                let payment_hash = probing_cookie_from_id(&payment_id, probing_cookie_secret);
 
@@ -395,21 +641,33 @@ impl OutboundPayments {
                }
 
                let route = Route { paths: vec![hops], payment_params: None };
-               let onion_session_privs = self.add_new_pending_payment(payment_hash, None, payment_id, &route, keys_manager, best_block_height)?;
+               let onion_session_privs = self.add_new_pending_payment(payment_hash, None, payment_id, &route, Retry::Attempts(0), None, entropy_source, best_block_height)?;
 
-               match self.send_payment_internal(&route, payment_hash, &None, None, payment_id, None, onion_session_privs, keys_manager, best_block_height, send_payment_along_path) {
+               match self.pay_route_internal(&route, payment_hash, &None, None, payment_id, None, onion_session_privs, node_signer, best_block_height, &send_payment_along_path) {
                        Ok(()) => Ok((payment_hash, payment_id)),
-                       Err(e) => Err(e)
+                       Err(e) => {
+                               self.remove_outbound_if_all_failed(payment_id, &e);
+                               Err(e)
+                       }
                }
        }
 
-       pub(super) fn add_new_pending_payment<K: Deref>(
+       #[cfg(test)]
+       pub(super) fn test_add_new_pending_payment<ES: Deref>(
                &self, payment_hash: PaymentHash, payment_secret: Option<PaymentSecret>, payment_id: PaymentId,
-               route: &Route, keys_manager: &K, best_block_height: u32
-       ) -> Result<Vec<[u8; 32]>, PaymentSendFailure> where K::Target: KeysInterface {
+               route: &Route, retry_strategy: Retry, entropy_source: &ES, best_block_height: u32
+       ) -> Result<Vec<[u8; 32]>, PaymentSendFailure> where ES::Target: EntropySource {
+               self.add_new_pending_payment(payment_hash, payment_secret, payment_id, route, retry_strategy, None, entropy_source, best_block_height)
+       }
+
+       pub(super) fn add_new_pending_payment<ES: Deref>(
+               &self, payment_hash: PaymentHash, payment_secret: Option<PaymentSecret>, payment_id: PaymentId,
+               route: &Route, retry_strategy: Retry, route_params: Option<RouteParameters>,
+               entropy_source: &ES, best_block_height: u32
+       ) -> Result<Vec<[u8; 32]>, PaymentSendFailure> where ES::Target: EntropySource {
                let mut onion_session_privs = Vec::with_capacity(route.paths.len());
                for _ in 0..route.paths.len() {
-                       onion_session_privs.push(keys_manager.get_secure_random_bytes());
+                       onion_session_privs.push(entropy_source.get_secure_random_bytes());
                }
 
                let mut pending_outbounds = self.pending_outbound_payments.lock().unwrap();
@@ -417,6 +675,9 @@ impl OutboundPayments {
                        hash_map::Entry::Occupied(_) => Err(PaymentSendFailure::DuplicatePayment),
                        hash_map::Entry::Vacant(entry) => {
                                let payment = entry.insert(PendingOutboundPayment::Retryable {
+                                       retry_strategy,
+                                       attempts: PaymentAttempts::new(),
+                                       route_params,
                                        session_privs: HashSet::new(),
                                        pending_amt_msat: 0,
                                        pending_fee_msat: Some(0),
@@ -435,13 +696,14 @@ impl OutboundPayments {
                }
        }
 
-       fn send_payment_internal<K: Deref, F>(
+       fn pay_route_internal<NS: Deref, F>(
                &self, route: &Route, payment_hash: PaymentHash, payment_secret: &Option<PaymentSecret>,
                keysend_preimage: Option<PaymentPreimage>, payment_id: PaymentId, recv_value_msat: Option<u64>,
-               onion_session_privs: Vec<[u8; 32]>, keys_manager: &K, best_block_height: u32,
-               send_payment_along_path: F) -> Result<(), PaymentSendFailure>
+               onion_session_privs: Vec<[u8; 32]>, node_signer: &NS, best_block_height: u32,
+               send_payment_along_path: &F
+       ) -> Result<(), PaymentSendFailure>
        where
-               K::Target: KeysInterface,
+               NS::Target: NodeSigner,
                F: Fn(&Vec<RouteHop>, &Option<PaymentParameters>, &PaymentHash, &Option<PaymentSecret>, u64,
                   u32, PaymentId, &Option<PaymentPreimage>, [u8; 32]) -> Result<(), APIError>
        {
@@ -452,7 +714,7 @@ impl OutboundPayments {
                        return Err(PaymentSendFailure::ParameterError(APIError::APIMisuseError{err: "Payment secret is required for multi-path payments".to_string()}));
                }
                let mut total_value = 0;
-               let our_node_id = keys_manager.get_node_id(Recipient::Node).unwrap(); // TODO no unwrap
+               let our_node_id = node_signer.get_node_id(Recipient::Node).unwrap(); // TODO no unwrap
                let mut path_errs = Vec::with_capacity(route.paths.len());
                'path_check: for path in route.paths.iter() {
                        if path.len() < 1 || path.len() > 20 {
@@ -533,10 +795,6 @@ impl OutboundPayments {
                                } else { None },
                        })
                } else if has_err {
-                       // If we failed to send any paths, we should remove the new PaymentId from the
-                       // `pending_outbound_payments` map, as the user isn't expected to `abandon_payment`.
-                       let removed = self.pending_outbound_payments.lock().unwrap().remove(&payment_id).is_some();
-                       debug_assert!(removed, "We should always have a pending payment to remove here");
                        Err(PaymentSendFailure::AllFailedResendSafe(results.drain(..).map(|r| r.unwrap_err()).collect()))
                } else {
                        Ok(())
@@ -544,25 +802,36 @@ impl OutboundPayments {
        }
 
        #[cfg(test)]
-       pub(super) fn test_send_payment_internal<K: Deref, F>(
+       pub(super) fn test_send_payment_internal<NS: Deref, F>(
                &self, route: &Route, payment_hash: PaymentHash, payment_secret: &Option<PaymentSecret>,
                keysend_preimage: Option<PaymentPreimage>, payment_id: PaymentId, recv_value_msat: Option<u64>,
-               onion_session_privs: Vec<[u8; 32]>, keys_manager: &K, best_block_height: u32,
-               send_payment_along_path: F) -> Result<(), PaymentSendFailure>
+               onion_session_privs: Vec<[u8; 32]>, node_signer: &NS, best_block_height: u32,
+               send_payment_along_path: F
+       ) -> Result<(), PaymentSendFailure>
        where
-               K::Target: KeysInterface,
+               NS::Target: NodeSigner,
                F: Fn(&Vec<RouteHop>, &Option<PaymentParameters>, &PaymentHash, &Option<PaymentSecret>, u64,
                   u32, PaymentId, &Option<PaymentPreimage>, [u8; 32]) -> Result<(), APIError>
        {
-               self.send_payment_internal(route, payment_hash, payment_secret, keysend_preimage, payment_id,
-                       recv_value_msat, onion_session_privs, keys_manager, best_block_height,
-                       send_payment_along_path)
+               self.pay_route_internal(route, payment_hash, payment_secret, keysend_preimage, payment_id,
+                       recv_value_msat, onion_session_privs, node_signer, best_block_height,
+                       &send_payment_along_path)
+                       .map_err(|e| { self.remove_outbound_if_all_failed(payment_id, &e); e })
+       }
+
+       // If we failed to send any paths, we should remove the new PaymentId from the
+       // `pending_outbound_payments` map, as the user isn't expected to `abandon_payment`.
+       fn remove_outbound_if_all_failed(&self, payment_id: PaymentId, err: &PaymentSendFailure) {
+               if let &PaymentSendFailure::AllFailedResendSafe(_) = err {
+                       let removed = self.pending_outbound_payments.lock().unwrap().remove(&payment_id).is_some();
+                       debug_assert!(removed, "We should always have a pending payment to remove here");
+               }
        }
 
        pub(super) fn claim_htlc<L: Deref>(
                &self, payment_id: PaymentId, payment_preimage: PaymentPreimage, session_priv: SecretKey,
-               path: Vec<RouteHop>, from_onchain: bool, pending_events: &Mutex<Vec<events::Event>>, logger: &L)
-        where L::Target: Logger {
+               path: Vec<RouteHop>, from_onchain: bool, pending_events: &Mutex<Vec<events::Event>>, logger: &L
+       ) where L::Target: Logger {
                let mut session_priv_bytes = [0; 32];
                session_priv_bytes.copy_from_slice(&session_priv[..]);
                let mut outbounds = self.pending_outbound_payments.lock().unwrap();
@@ -671,14 +940,20 @@ impl OutboundPayments {
                &self, source: &HTLCSource, payment_hash: &PaymentHash, onion_error: &HTLCFailReason,
                path: &Vec<RouteHop>, session_priv: &SecretKey, payment_id: &PaymentId,
                payment_params: &Option<PaymentParameters>, probing_cookie_secret: [u8; 32],
-               secp_ctx: &Secp256k1<secp256k1::All>, pending_events: &Mutex<Vec<events::Event>>, logger: &L)
-       where L::Target: Logger {
+               secp_ctx: &Secp256k1<secp256k1::All>, pending_events: &Mutex<Vec<events::Event>>, logger: &L
+       ) where L::Target: Logger {
+               #[cfg(test)]
+               let (network_update, short_channel_id, payment_retryable, onion_error_code, onion_error_data) = onion_error.decode_onion_failure(secp_ctx, logger, &source);
+               #[cfg(not(test))]
+               let (network_update, short_channel_id, payment_retryable, _, _) = onion_error.decode_onion_failure(secp_ctx, logger, &source);
+
                let mut session_priv_bytes = [0; 32];
                session_priv_bytes.copy_from_slice(&session_priv[..]);
                let mut outbounds = self.pending_outbound_payments.lock().unwrap();
                let mut all_paths_failed = false;
                let mut full_failure_ev = None;
-               if let hash_map::Entry::Occupied(mut payment) = outbounds.entry(*payment_id) {
+               let mut pending_retry_ev = None;
+               let attempts_remaining = if let hash_map::Entry::Occupied(mut payment) = outbounds.entry(*payment_id) {
                        if !payment.get_mut().remove(&session_priv_bytes, Some(&path)) {
                                log_trace!(logger, "Received duplicative fail for HTLC with payment_hash {}", log_bytes!(payment_hash.0));
                                return
@@ -687,6 +962,10 @@ impl OutboundPayments {
                                log_trace!(logger, "Received failure of HTLC with payment_hash {} after payment completion", log_bytes!(payment_hash.0));
                                return
                        }
+                       let is_retryable_now = payment.get().is_retryable_now();
+                       if let Some(scid) = short_channel_id {
+                               payment.get_mut().insert_previously_failed_scid(scid);
+                       }
                        if payment.get().remaining_parts() == 0 {
                                all_paths_failed = true;
                                if payment.get().abandoned() {
@@ -697,10 +976,12 @@ impl OutboundPayments {
                                        payment.remove();
                                }
                        }
+                       is_retryable_now
                } else {
                        log_trace!(logger, "Received duplicative fail for HTLC with payment_hash {}", log_bytes!(payment_hash.0));
                        return
-               }
+               };
+               core::mem::drop(outbounds);
                let mut retry = if let Some(payment_params_data) = payment_params {
                        let path_last_hop = path.last().expect("Outbound payments must have had a valid path");
                        Some(RouteParameters {
@@ -712,11 +993,6 @@ impl OutboundPayments {
                log_trace!(logger, "Failing outbound payment HTLC with payment_hash {}", log_bytes!(payment_hash.0));
 
                let path_failure = {
-       #[cfg(test)]
-                       let (network_update, short_channel_id, payment_retryable, onion_error_code, onion_error_data) = onion_error.decode_onion_failure(secp_ctx, logger, &source);
-       #[cfg(not(test))]
-                       let (network_update, short_channel_id, payment_retryable, _, _) = onion_error.decode_onion_failure(secp_ctx, logger, &source);
-
                        if payment_is_probe(payment_hash, &payment_id, probing_cookie_secret) {
                                if !payment_retryable {
                                        events::Event::ProbeSuccessful {
@@ -739,6 +1015,12 @@ impl OutboundPayments {
                                if let Some(scid) = short_channel_id {
                                        retry.as_mut().map(|r| r.payment_params.previously_failed_channels.push(scid));
                                }
+                               if payment_retryable && attempts_remaining && retry.is_some() {
+                                       debug_assert!(full_failure_ev.is_none());
+                                       pending_retry_ev = Some(events::Event::PendingHTLCsForwardable {
+                                               time_forwardable: Duration::from_millis(MIN_HTLC_RELAY_HOLDING_CELL_MILLIS),
+                                       });
+                               }
                                events::Event::PaymentPathFailed {
                                        payment_id: Some(*payment_id),
                                        payment_hash: payment_hash.clone(),
@@ -758,6 +1040,7 @@ impl OutboundPayments {
                let mut pending_events = pending_events.lock().unwrap();
                pending_events.push(path_failure);
                if let Some(ev) = full_failure_ev { pending_events.push(ev); }
+               if let Some(ev) = pending_retry_ev { pending_events.push(ev); }
        }
 
        pub(super) fn abandon_payment(&self, payment_id: PaymentId) -> Option<events::Event> {
@@ -818,8 +1101,11 @@ impl_writeable_tlv_based_enum_upgradable!(PendingOutboundPayment,
                (0, session_privs, required),
                (1, pending_fee_msat, option),
                (2, payment_hash, required),
+               (not_written, retry_strategy, (static_value, Retry::Attempts(0))),
                (4, payment_secret, option),
+               (not_written, attempts, (static_value, PaymentAttempts::new())),
                (6, total_msat, required),
+               (not_written, route_params, (static_value, None)),
                (8, pending_amt_msat, required),
                (10, starting_block_height, required),
        },
@@ -828,3 +1114,99 @@ impl_writeable_tlv_based_enum_upgradable!(PendingOutboundPayment,
                (2, payment_hash, required),
        },
 );
+
+#[cfg(test)]
+mod tests {
+       use bitcoin::blockdata::constants::genesis_block;
+       use bitcoin::network::constants::Network;
+       use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
+
+       use crate::ln::PaymentHash;
+       use crate::ln::channelmanager::{PaymentId, PaymentSendFailure};
+       use crate::ln::msgs::{ErrorAction, LightningError};
+       use crate::ln::outbound_payment::{OutboundPayments, Retry};
+       use crate::routing::gossip::NetworkGraph;
+       use crate::routing::router::{InFlightHtlcs, PaymentParameters, Route, RouteParameters};
+       use crate::sync::Arc;
+       use crate::util::errors::APIError;
+       use crate::util::test_utils;
+
+       #[test]
+       #[cfg(feature = "std")]
+       fn fails_paying_after_expiration() {
+               do_fails_paying_after_expiration(false);
+               do_fails_paying_after_expiration(true);
+       }
+       #[cfg(feature = "std")]
+       fn do_fails_paying_after_expiration(on_retry: bool) {
+               let outbound_payments = OutboundPayments::new();
+               let logger = test_utils::TestLogger::new();
+               let genesis_hash = genesis_block(Network::Testnet).header.block_hash();
+               let network_graph = Arc::new(NetworkGraph::new(genesis_hash, &logger));
+               let router = test_utils::TestRouter::new(network_graph);
+               let secp_ctx = Secp256k1::new();
+               let keys_manager = test_utils::TestKeysInterface::new(&[0; 32], Network::Testnet);
+
+               let past_expiry_time = std::time::SystemTime::UNIX_EPOCH.elapsed().unwrap().as_secs() - 2;
+               let payment_params = PaymentParameters::from_node_id(
+                       PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap()))
+                       .with_expiry_time(past_expiry_time);
+               let expired_route_params = RouteParameters {
+                       payment_params,
+                       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, &|_, _, _, _, _, _, _, _, _| Ok(())).unwrap_err()
+               } else {
+                       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, |_, _, _, _, _, _, _, _, _| Ok(())).unwrap_err()
+               };
+               if let PaymentSendFailure::ParameterError(APIError::APIMisuseError { err }) = err {
+                       assert!(err.contains("Invoice expired"));
+               } else { panic!("Unexpected error"); }
+       }
+
+       #[test]
+       fn find_route_error() {
+               do_find_route_error(false);
+               do_find_route_error(true);
+       }
+       fn do_find_route_error(on_retry: bool) {
+               let outbound_payments = OutboundPayments::new();
+               let logger = test_utils::TestLogger::new();
+               let genesis_hash = genesis_block(Network::Testnet).header.block_hash();
+               let network_graph = Arc::new(NetworkGraph::new(genesis_hash, &logger));
+               let router = test_utils::TestRouter::new(network_graph);
+               let secp_ctx = Secp256k1::new();
+               let keys_manager = test_utils::TestKeysInterface::new(&[0; 32], Network::Testnet);
+
+               router.expect_find_route(Err(LightningError { err: String::new(), action: ErrorAction::IgnoreError }));
+
+               let payment_params = PaymentParameters::from_node_id(
+                       PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap()));
+               let route_params = RouteParameters {
+                       payment_params,
+                       final_value_msat: 0,
+                       final_cltv_expiry_delta: 0,
+               };
+               let err = if on_retry {
+                       outbound_payments.add_new_pending_payment(PaymentHash([0; 32]), None, PaymentId([0; 32]),
+                       &Route { paths: vec![], payment_params: None }, Retry::Attempts(1), Some(route_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, &|_, _, _, _, _, _, _, _, _| Ok(())).unwrap_err()
+               } else {
+                       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, |_, _, _, _, _, _, _, _, _| Ok(())).unwrap_err()
+               };
+               if let PaymentSendFailure::ParameterError(APIError::APIMisuseError { err }) = err {
+                       assert!(err.contains("Failed to find a route"));
+               } else { panic!("Unexpected error"); }
+       }
+}