Merge pull request #2534 from tnull/2023-08-upstream-preflight-probing
[rust-lightning] / lightning / src / ln / outbound_payment.rs
index 81b95f1ce07230ccd7b46339fd7c28ea6bcaba8e..023412e1afb56cdcdd0a2d9195064e5744ccab6c 100644 (file)
@@ -13,33 +13,52 @@ use bitcoin::hashes::Hash;
 use bitcoin::hashes::sha256::Hash as Sha256;
 use bitcoin::secp256k1::{self, Secp256k1, SecretKey};
 
-use crate::chain::keysinterface::{EntropySource, NodeSigner, Recipient};
+use crate::sign::{EntropySource, NodeSigner, Recipient};
+use crate::events::{self, PaymentFailureReason};
 use crate::ln::{PaymentHash, PaymentPreimage, PaymentSecret};
-use crate::ln::channelmanager::{ChannelDetails, HTLCSource, IDEMPOTENCY_TIMEOUT_TICKS, PaymentId};
-use crate::ln::channelmanager::MIN_FINAL_CLTV_EXPIRY_DELTA as LDK_DEFAULT_MIN_FINAL_CLTV_EXPIRY_DELTA;
-use crate::ln::msgs::DecodeError;
-use crate::ln::onion_utils::HTLCFailReason;
-use crate::routing::router::{InFlightHtlcs, PaymentParameters, Route, RouteHop, RouteParameters, RoutePath, Router};
+use crate::ln::channelmanager::{ChannelDetails, EventCompletionAction, HTLCSource, PaymentId};
+use crate::ln::onion_utils::{DecodedOnionFailure, HTLCFailReason};
+use crate::offers::invoice::Bolt12Invoice;
+use crate::routing::router::{InFlightHtlcs, Path, PaymentParameters, Route, RouteParameters, 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 crate::util::ser::ReadableArgs;
 
-use core::cmp;
 use core::fmt::{self, Display, Formatter};
 use core::ops::Deref;
 
 use crate::prelude::*;
 use crate::sync::Mutex;
 
+/// The number of ticks of [`ChannelManager::timer_tick_occurred`] until we time-out the idempotency
+/// of payments by [`PaymentId`]. See [`OutboundPayments::remove_stale_payments`].
+///
+/// [`ChannelManager::timer_tick_occurred`]: crate::ln::channelmanager::ChannelManager::timer_tick_occurred
+pub(crate) const IDEMPOTENCY_TIMEOUT_TICKS: u8 = 7;
+
+/// The number of ticks of [`ChannelManager::timer_tick_occurred`] until an invoice request without
+/// a response is timed out.
+///
+/// [`ChannelManager::timer_tick_occurred`]: crate::ln::channelmanager::ChannelManager::timer_tick_occurred
+const INVOICE_REQUEST_TIMEOUT_TICKS: u8 = 3;
+
 /// Stores the session_priv for each part of a payment that is still pending. For versions 0.0.102
 /// and later, also stores information for retrying the payment.
 pub(crate) enum PendingOutboundPayment {
        Legacy {
                session_privs: HashSet<[u8; 32]>,
        },
+       AwaitingInvoice {
+               timer_ticks_without_response: u8,
+               retry_strategy: Retry,
+       },
+       InvoiceReceived {
+               payment_hash: PaymentHash,
+               retry_strategy: Retry,
+       },
        Retryable {
                retry_strategy: Option<Retry>,
                attempts: PaymentAttempts,
@@ -47,7 +66,9 @@ pub(crate) enum PendingOutboundPayment {
                session_privs: HashSet<[u8; 32]>,
                payment_hash: PaymentHash,
                payment_secret: Option<PaymentSecret>,
+               payment_metadata: Option<Vec<u8>>,
                keysend_preimage: Option<PaymentPreimage>,
+               custom_tlvs: Vec<(u64, Vec<u8>)>,
                pending_amt_msat: u64,
                /// Used to track the fee paid. Only present if the payment was serialized on 0.0.103+.
                pending_fee_msat: Option<u64>,
@@ -61,6 +82,7 @@ pub(crate) enum PendingOutboundPayment {
        /// and add a pending payment that was already fulfilled.
        Fulfilled {
                session_privs: HashSet<[u8; 32]>,
+               /// Filled in for any payment which moved to `Fulfilled` on LDK 0.0.104 or later.
                payment_hash: Option<PaymentHash>,
                timer_ticks_without_htlcs: u8,
        },
@@ -69,6 +91,8 @@ pub(crate) enum PendingOutboundPayment {
        Abandoned {
                session_privs: HashSet<[u8; 32]>,
                payment_hash: PaymentHash,
+               /// Will be `None` if the payment was serialized before 0.0.115.
+               reason: Option<PaymentFailureReason>,
        },
 }
 
@@ -80,7 +104,9 @@ impl PendingOutboundPayment {
        }
        fn is_auto_retryable_now(&self) -> bool {
                match self {
-                       PendingOutboundPayment::Retryable { retry_strategy: Some(strategy), attempts, .. } => {
+                       PendingOutboundPayment::Retryable {
+                               retry_strategy: Some(strategy), attempts, payment_params: Some(_), ..
+                       } => {
                                strategy.is_retryable_now(&attempts)
                        },
                        _ => false,
@@ -98,19 +124,17 @@ impl PendingOutboundPayment {
                        _ => false,
                }
        }
-       fn payment_parameters(&mut self) -> Option<&mut PaymentParameters> {
-               match self {
-                       PendingOutboundPayment::Retryable { payment_params: Some(ref mut params), .. } => {
-                               Some(params)
-                       },
-                       _ => None,
-               }
-       }
        pub fn insert_previously_failed_scid(&mut self, scid: u64) {
                if let PendingOutboundPayment::Retryable { payment_params: Some(params), .. } = self {
                        params.previously_failed_channels.push(scid);
                }
        }
+       fn is_awaiting_invoice(&self) -> bool {
+               match self {
+                       PendingOutboundPayment::AwaitingInvoice { .. } => true,
+                       _ => false,
+               }
+       }
        pub(super) fn is_fulfilled(&self) -> bool {
                match self {
                        PendingOutboundPayment::Fulfilled { .. } => true,
@@ -133,6 +157,8 @@ impl PendingOutboundPayment {
        fn payment_hash(&self) -> Option<PaymentHash> {
                match self {
                        PendingOutboundPayment::Legacy { .. } => None,
+                       PendingOutboundPayment::AwaitingInvoice { .. } => None,
+                       PendingOutboundPayment::InvoiceReceived { payment_hash, .. } => Some(*payment_hash),
                        PendingOutboundPayment::Retryable { payment_hash, .. } => Some(*payment_hash),
                        PendingOutboundPayment::Fulfilled { payment_hash, .. } => *payment_hash,
                        PendingOutboundPayment::Abandoned { payment_hash, .. } => Some(*payment_hash),
@@ -145,68 +171,72 @@ impl PendingOutboundPayment {
                        PendingOutboundPayment::Legacy { session_privs } |
                                PendingOutboundPayment::Retryable { session_privs, .. } |
                                PendingOutboundPayment::Fulfilled { session_privs, .. } |
-                               PendingOutboundPayment::Abandoned { session_privs, .. }
-                       => session_privs,
+                               PendingOutboundPayment::Abandoned { session_privs, .. } => session_privs,
+                       PendingOutboundPayment::AwaitingInvoice { .. } |
+                               PendingOutboundPayment::InvoiceReceived { .. } => { debug_assert!(false); return; },
                });
                let payment_hash = self.payment_hash();
                *self = PendingOutboundPayment::Fulfilled { session_privs, payment_hash, timer_ticks_without_htlcs: 0 };
        }
 
-       fn mark_abandoned(&mut self) -> Result<(), ()> {
-               let mut session_privs = HashSet::new();
-               let our_payment_hash;
-               core::mem::swap(&mut session_privs, match self {
-                       PendingOutboundPayment::Legacy { .. } |
-                       PendingOutboundPayment::Fulfilled { .. } =>
-                               return Err(()),
-                       PendingOutboundPayment::Retryable { session_privs, payment_hash, .. } |
-                       PendingOutboundPayment::Abandoned { session_privs, payment_hash, .. } => {
-                               our_payment_hash = *payment_hash;
-                               session_privs
-                       },
-               });
-               *self = PendingOutboundPayment::Abandoned { session_privs, payment_hash: our_payment_hash };
-               Ok(())
+       fn mark_abandoned(&mut self, reason: PaymentFailureReason) {
+               if let PendingOutboundPayment::Retryable { session_privs, payment_hash, .. } = self {
+                       let mut our_session_privs = HashSet::new();
+                       core::mem::swap(&mut our_session_privs, session_privs);
+                       *self = PendingOutboundPayment::Abandoned {
+                               session_privs: our_session_privs,
+                               payment_hash: *payment_hash,
+                               reason: Some(reason)
+                       };
+               } else if let PendingOutboundPayment::InvoiceReceived { payment_hash, .. } = self {
+                       *self = PendingOutboundPayment::Abandoned {
+                               session_privs: HashSet::new(),
+                               payment_hash: *payment_hash,
+                               reason: Some(reason)
+                       };
+               }
        }
 
        /// panics if path is None and !self.is_fulfilled
-       fn remove(&mut self, session_priv: &[u8; 32], path: Option<&Vec<RouteHop>>) -> bool {
+       fn remove(&mut self, session_priv: &[u8; 32], path: Option<&Path>) -> bool {
                let remove_res = match self {
                        PendingOutboundPayment::Legacy { session_privs } |
                                PendingOutboundPayment::Retryable { session_privs, .. } |
                                PendingOutboundPayment::Fulfilled { session_privs, .. } |
                                PendingOutboundPayment::Abandoned { session_privs, .. } => {
                                        session_privs.remove(session_priv)
-                               }
+                               },
+                       PendingOutboundPayment::AwaitingInvoice { .. } |
+                               PendingOutboundPayment::InvoiceReceived { .. } => { debug_assert!(false); false },
                };
                if remove_res {
                        if let PendingOutboundPayment::Retryable { ref mut pending_amt_msat, ref mut pending_fee_msat, .. } = self {
                                let path = path.expect("Fulfilling a payment should always come with a path");
-                               let path_last_hop = path.last().expect("Outbound payments must have had a valid path");
-                               *pending_amt_msat -= path_last_hop.fee_msat;
+                               *pending_amt_msat -= path.final_value_msat();
                                if let Some(fee_msat) = pending_fee_msat.as_mut() {
-                                       *fee_msat -= path.get_path_fees();
+                                       *fee_msat -= path.fee_msat();
                                }
                        }
                }
                remove_res
        }
 
-       pub(super) fn insert(&mut self, session_priv: [u8; 32], path: &Vec<RouteHop>) -> bool {
+       pub(super) fn insert(&mut self, session_priv: [u8; 32], path: &Path) -> bool {
                let insert_res = match self {
                        PendingOutboundPayment::Legacy { session_privs } |
                                PendingOutboundPayment::Retryable { session_privs, .. } => {
                                        session_privs.insert(session_priv)
-                               }
+                               },
+                       PendingOutboundPayment::AwaitingInvoice { .. } |
+                               PendingOutboundPayment::InvoiceReceived { .. } => { debug_assert!(false); false },
                        PendingOutboundPayment::Fulfilled { .. } => false,
                        PendingOutboundPayment::Abandoned { .. } => false,
                };
                if insert_res {
                        if let PendingOutboundPayment::Retryable { ref mut pending_amt_msat, ref mut pending_fee_msat, .. } = self {
-                               let path_last_hop = path.last().expect("Outbound payments must have had a valid path");
-                               *pending_amt_msat += path_last_hop.fee_msat;
+                               *pending_amt_msat += path.final_value_msat();
                                if let Some(fee_msat) = pending_fee_msat.as_mut() {
-                                       *fee_msat += path.get_path_fees();
+                                       *fee_msat += path.fee_msat();
                                }
                        }
                }
@@ -220,7 +250,9 @@ impl PendingOutboundPayment {
                                PendingOutboundPayment::Fulfilled { session_privs, .. } |
                                PendingOutboundPayment::Abandoned { session_privs, .. } => {
                                        session_privs.len()
-                               }
+                               },
+                       PendingOutboundPayment::AwaitingInvoice { .. } => 0,
+                       PendingOutboundPayment::InvoiceReceived { .. } => 0,
                }
        }
 }
@@ -232,8 +264,8 @@ pub enum Retry {
        ///
        /// Each attempt may be multiple HTLCs along multiple paths if the router decides to split up a
        /// retry, and may retry multiple failed HTLCs at once if they failed around the same time and
-       /// were retried along a route from a single call to [`Router::find_route`].
-       Attempts(usize),
+       /// were retried along a route from a single call to [`Router::find_route_with_id`].
+       Attempts(u32),
        #[cfg(not(feature = "no-std"))]
        /// 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.
@@ -242,6 +274,19 @@ pub enum Retry {
        Timeout(core::time::Duration),
 }
 
+#[cfg(feature = "no-std")]
+impl_writeable_tlv_based_enum!(Retry,
+       ;
+       (0, Attempts)
+);
+
+#[cfg(not(feature = "no-std"))]
+impl_writeable_tlv_based_enum!(Retry,
+       ;
+       (0, Attempts),
+       (2, Timeout)
+);
+
 impl Retry {
        pub(crate) fn is_retryable_now(&self, attempts: &PaymentAttempts) -> bool {
                match (self, attempts) {
@@ -250,7 +295,7 @@ impl Retry {
                        },
                        #[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),
+                               *max_duration >= crate::util::time::MonotonicTime::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),
@@ -275,13 +320,17 @@ pub(crate) type PaymentAttempts = PaymentAttemptsUsingTime<ConfiguredTime>;
 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,
+       pub(crate) count: u32,
        /// This field is only used when retry is `Retry::Timeout` which is only build with feature std
-       first_attempted_at: T
+       #[cfg(not(feature = "no-std"))]
+       first_attempted_at: T,
+       #[cfg(feature = "no-std")]
+       phantom: core::marker::PhantomData<T>,
+
 }
 
 #[cfg(not(any(feature = "no-std", test)))]
-type ConfiguredTime = std::time::Instant;
+type ConfiguredTime = crate::util::time::MonotonicTime;
 #[cfg(feature = "no-std")]
 type ConfiguredTime = crate::util::time::Eternity;
 #[cfg(all(not(feature = "no-std"), test))]
@@ -291,7 +340,10 @@ impl<T: Time> PaymentAttemptsUsingTime<T> {
        pub(crate) fn new() -> Self {
                PaymentAttemptsUsingTime {
                        count: 0,
-                       first_attempted_at: T::now()
+                       #[cfg(not(feature = "no-std"))]
+                       first_attempted_at: T::now(),
+                       #[cfg(feature = "no-std")]
+                       phantom: core::marker::PhantomData,
                }
        }
 }
@@ -310,13 +362,13 @@ impl<T: Time> Display for PaymentAttemptsUsingTime<T> {
        }
 }
 
-/// Indicates an immediate error on [`ChannelManager::send_payment_with_retry`]. Further errors
-/// may be surfaced later via [`Event::PaymentPathFailed`] and [`Event::PaymentFailed`].
+/// Indicates an immediate error on [`ChannelManager::send_payment`]. 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)]
+/// [`ChannelManager::send_payment`]: crate::ln::channelmanager::ChannelManager::send_payment
+/// [`Event::PaymentPathFailed`]: crate::events::Event::PaymentPathFailed
+/// [`Event::PaymentFailed`]: crate::events::Event::PaymentFailed
+#[derive(Clone, Debug, PartialEq, Eq)]
 pub enum RetryableSendFailure {
        /// The provided [`PaymentParameters::expiry_time`] indicated that the payment has expired. Note
        /// that this error is *not* caused by [`Retry::Timeout`].
@@ -329,17 +381,17 @@ pub enum RetryableSendFailure {
        /// 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
+       /// [`Event::PaymentSent`]: crate::events::Event::PaymentSent
+       /// [`Event::PaymentFailed`]: crate::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.
+/// If a payment fails to send with [`ChannelManager::send_payment_with_route`], 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)]
+/// [`ChannelManager::send_payment_with_route`]: crate::ln::channelmanager::ChannelManager::send_payment_with_route
+#[derive(Clone, Debug, PartialEq, Eq)]
 pub enum PaymentSendFailure {
        /// A parameter which was passed to send_payment was invalid, preventing us from attempting to
        /// send the payment at all.
@@ -349,8 +401,8 @@ pub enum PaymentSendFailure {
        /// Because the payment failed outright, no payment tracking is done and no
        /// [`Event::PaymentPathFailed`] or [`Event::PaymentFailed`] events will be generated.
        ///
-       /// [`Event::PaymentPathFailed`]: crate::util::events::Event::PaymentPathFailed
-       /// [`Event::PaymentFailed`]: crate::util::events::Event::PaymentFailed
+       /// [`Event::PaymentPathFailed`]: crate::events::Event::PaymentPathFailed
+       /// [`Event::PaymentFailed`]: crate::events::Event::PaymentFailed
        ParameterError(APIError),
        /// A parameter in a single path which was passed to send_payment was invalid, preventing us
        /// from attempting to send the payment at all.
@@ -363,8 +415,8 @@ pub enum PaymentSendFailure {
        /// The results here are ordered the same as the paths in the route object which was passed to
        /// send_payment.
        ///
-       /// [`Event::PaymentPathFailed`]: crate::util::events::Event::PaymentPathFailed
-       /// [`Event::PaymentFailed`]: crate::util::events::Event::PaymentFailed
+       /// [`Event::PaymentPathFailed`]: crate::events::Event::PaymentPathFailed
+       /// [`Event::PaymentFailed`]: crate::events::Event::PaymentFailed
        PathParameterError(Vec<Result<(), APIError>>),
        /// All paths which were attempted failed to send, with no channel state change taking place.
        /// You can freely resend the payment in full (though you probably want to do so over different
@@ -373,15 +425,15 @@ pub enum PaymentSendFailure {
        /// Because the payment failed outright, no payment tracking is done and no
        /// [`Event::PaymentPathFailed`] or [`Event::PaymentFailed`] events will be generated.
        ///
-       /// [`Event::PaymentPathFailed`]: crate::util::events::Event::PaymentPathFailed
-       /// [`Event::PaymentFailed`]: crate::util::events::Event::PaymentFailed
+       /// [`Event::PaymentPathFailed`]: crate::events::Event::PaymentPathFailed
+       /// [`Event::PaymentFailed`]: crate::events::Event::PaymentFailed
        AllFailedResendSafe(Vec<APIError>),
        /// 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
+       /// [`Event::PaymentSent`]: crate::events::Event::PaymentSent
+       /// [`Event::PaymentFailed`]: crate::events::Event::PaymentFailed
        DuplicatePayment,
        /// Some paths that were attempted failed to send, though some paths may have succeeded. At least
        /// some paths have irrevocably committed to the HTLC.
@@ -404,6 +456,164 @@ pub enum PaymentSendFailure {
        },
 }
 
+/// An error when attempting to pay a BOLT 12 invoice.
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub(super) enum Bolt12PaymentError {
+       /// The invoice was not requested.
+       UnexpectedInvoice,
+       /// Payment for an invoice with the corresponding [`PaymentId`] was already initiated.
+       DuplicateInvoice,
+}
+
+/// Indicates that we failed to send a payment probe. Further errors may be surfaced later via
+/// [`Event::ProbeFailed`].
+///
+/// [`Event::ProbeFailed`]: crate::events::Event::ProbeFailed
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub enum ProbeSendFailure {
+       /// We were unable to find a route to the destination.
+       RouteNotFound,
+       /// We failed to send the payment probes.
+       SendingFailed(PaymentSendFailure),
+}
+
+/// Information which is provided, encrypted, to the payment recipient when sending HTLCs.
+///
+/// This should generally be constructed with data communicated to us from the recipient (via a
+/// BOLT11 or BOLT12 invoice).
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct RecipientOnionFields {
+       /// The [`PaymentSecret`] is an arbitrary 32 bytes provided by the recipient for us to repeat
+       /// in the onion. It is unrelated to `payment_hash` (or [`PaymentPreimage`]) and exists to
+       /// authenticate the sender to the recipient and prevent payment-probing (deanonymization)
+       /// attacks.
+       ///
+       /// If you do not have one, the [`Route`] you pay over must not contain multiple paths as
+       /// multi-path payments require a recipient-provided secret.
+       ///
+       /// Some implementations may reject spontaneous payments with payment secrets, so you may only
+       /// want to provide a secret for a spontaneous payment if MPP is needed and you know your
+       /// recipient will not reject it.
+       pub payment_secret: Option<PaymentSecret>,
+       /// The payment metadata serves a similar purpose as [`Self::payment_secret`] but is of
+       /// arbitrary length. This gives recipients substantially more flexibility to receive
+       /// additional data.
+       ///
+       /// In LDK, while the [`Self::payment_secret`] is fixed based on an internal authentication
+       /// scheme to authenticate received payments against expected payments and invoices, this field
+       /// is not used in LDK for received payments, and can be used to store arbitrary data in
+       /// invoices which will be received with the payment.
+       ///
+       /// Note that this field was added to the lightning specification more recently than
+       /// [`Self::payment_secret`] and while nearly all lightning senders support secrets, metadata
+       /// may not be supported as universally.
+       pub payment_metadata: Option<Vec<u8>>,
+       /// See [`Self::custom_tlvs`] for more info.
+       pub(super) custom_tlvs: Vec<(u64, Vec<u8>)>,
+}
+
+impl_writeable_tlv_based!(RecipientOnionFields, {
+       (0, payment_secret, option),
+       (1, custom_tlvs, optional_vec),
+       (2, payment_metadata, option),
+});
+
+impl RecipientOnionFields {
+       /// Creates a [`RecipientOnionFields`] from only a [`PaymentSecret`]. This is the most common
+       /// set of onion fields for today's BOLT11 invoices - most nodes require a [`PaymentSecret`]
+       /// but do not require or provide any further data.
+       pub fn secret_only(payment_secret: PaymentSecret) -> Self {
+               Self { payment_secret: Some(payment_secret), payment_metadata: None, custom_tlvs: Vec::new() }
+       }
+
+       /// Creates a new [`RecipientOnionFields`] with no fields. This generally does not create
+       /// payable HTLCs except for single-path spontaneous payments, i.e. this should generally
+       /// only be used for calls to [`ChannelManager::send_spontaneous_payment`]. If you are sending
+       /// a spontaneous MPP this will not work as all MPP require payment secrets; you may
+       /// instead want to use [`RecipientOnionFields::secret_only`].
+       ///
+       /// [`ChannelManager::send_spontaneous_payment`]: super::channelmanager::ChannelManager::send_spontaneous_payment
+       /// [`RecipientOnionFields::secret_only`]: RecipientOnionFields::secret_only
+       pub fn spontaneous_empty() -> Self {
+               Self { payment_secret: None, payment_metadata: None, custom_tlvs: Vec::new() }
+       }
+
+       /// Creates a new [`RecipientOnionFields`] from an existing one, adding custom TLVs. Each
+       /// TLV is provided as a `(u64, Vec<u8>)` for the type number and serialized value
+       /// respectively. TLV type numbers must be unique and within the range
+       /// reserved for custom types, i.e. >= 2^16, otherwise this method will return `Err(())`.
+       ///
+       /// This method will also error for types in the experimental range which have been
+       /// standardized within the protocol, which only includes 5482373484 (keysend) for now.
+       ///
+       /// See [`Self::custom_tlvs`] for more info.
+       pub fn with_custom_tlvs(mut self, mut custom_tlvs: Vec<(u64, Vec<u8>)>) -> Result<Self, ()> {
+               custom_tlvs.sort_unstable_by_key(|(typ, _)| *typ);
+               let mut prev_type = None;
+               for (typ, _) in custom_tlvs.iter() {
+                       if *typ < 1 << 16 { return Err(()); }
+                       if *typ == 5482373484 { return Err(()); } // keysend
+                       match prev_type {
+                               Some(prev) if prev >= *typ => return Err(()),
+                               _ => {},
+                       }
+                       prev_type = Some(*typ);
+               }
+               self.custom_tlvs = custom_tlvs;
+               Ok(self)
+       }
+
+       /// Gets the custom TLVs that will be sent or have been received.
+       ///
+       /// Custom TLVs allow sending extra application-specific data with a payment. They provide
+       /// additional flexibility on top of payment metadata, as while other implementations may
+       /// require `payment_metadata` to reflect metadata provided in an invoice, custom TLVs
+       /// do not have this restriction.
+       ///
+       /// Note that if this field is non-empty, it will contain strictly increasing TLVs, each
+       /// represented by a `(u64, Vec<u8>)` for its type number and serialized value respectively.
+       /// This is validated when setting this field using [`Self::with_custom_tlvs`].
+       pub fn custom_tlvs(&self) -> &Vec<(u64, Vec<u8>)> {
+               &self.custom_tlvs
+       }
+
+       /// When we have received some HTLC(s) towards an MPP payment, as we receive further HTLC(s) we
+       /// have to make sure that some fields match exactly across the parts. For those that aren't
+       /// required to match, if they don't match we should remove them so as to not expose data
+       /// that's dependent on the HTLC receive order to users.
+       ///
+       /// Here we implement this, first checking compatibility then mutating two objects and then
+       /// dropping any remaining non-matching fields from both.
+       pub(super) fn check_merge(&mut self, further_htlc_fields: &mut Self) -> Result<(), ()> {
+               if self.payment_secret != further_htlc_fields.payment_secret { return Err(()); }
+               if self.payment_metadata != further_htlc_fields.payment_metadata { return Err(()); }
+
+               let tlvs = &mut self.custom_tlvs;
+               let further_tlvs = &mut further_htlc_fields.custom_tlvs;
+
+               let even_tlvs = tlvs.iter().filter(|(typ, _)| *typ % 2 == 0);
+               let further_even_tlvs = further_tlvs.iter().filter(|(typ, _)| *typ % 2 == 0);
+               if even_tlvs.ne(further_even_tlvs) { return Err(()) }
+
+               tlvs.retain(|tlv| further_tlvs.iter().any(|further_tlv| tlv == further_tlv));
+               further_tlvs.retain(|further_tlv| tlvs.iter().any(|tlv| tlv == further_tlv));
+
+               Ok(())
+       }
+}
+
+/// Arguments for [`super::channelmanager::ChannelManager::send_payment_along_path`].
+pub(super) struct SendAlongPathArgs<'a> {
+       pub path: &'a Path,
+       pub payment_hash: &'a PaymentHash,
+       pub recipient_onion: RecipientOnionFields,
+       pub total_value: u64,
+       pub cur_height: u32,
+       pub payment_id: PaymentId,
+       pub keysend_preimage: &'a Option<PaymentPreimage>,
+       pub session_priv_bytes: [u8; 32],
+}
+
 pub(super) struct OutboundPayments {
        pub(super) pending_outbound_payments: Mutex<HashMap<PaymentId, PendingOutboundPayment>>,
        pub(super) retry_lock: Mutex<()>,
@@ -418,11 +628,11 @@ impl OutboundPayments {
        }
 
        pub(super) fn send_payment<R: Deref, ES: Deref, NS: Deref, IH, SP, L: Deref>(
-               &self, payment_hash: PaymentHash, payment_secret: &Option<PaymentSecret>, payment_id: PaymentId,
+               &self, payment_hash: PaymentHash, recipient_onion: RecipientOnionFields, 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,
-               pending_events: &Mutex<Vec<events::Event>>, send_payment_along_path: SP,
+               pending_events: &Mutex<VecDeque<(events::Event, Option<EventCompletionAction>)>>, send_payment_along_path: SP,
        ) -> Result<(), RetryableSendFailure>
        where
                R::Target: Router,
@@ -430,37 +640,35 @@ impl OutboundPayments {
                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>,
+               SP: Fn(SendAlongPathArgs) -> Result<(), APIError>,
        {
-               self.send_payment_internal(payment_id, payment_hash, payment_secret, None, retry_strategy,
+               self.send_payment_internal(payment_id, payment_hash, recipient_onion, None, retry_strategy,
                        route_params, router, first_hops, &compute_inflight_htlcs, entropy_source, node_signer,
                        best_block_height, logger, pending_events, &send_payment_along_path)
        }
 
        pub(super) fn send_payment_with_route<ES: Deref, NS: Deref, F>(
-               &self, route: &Route, payment_hash: PaymentHash, payment_secret: &Option<PaymentSecret>,
+               &self, route: &Route, payment_hash: PaymentHash, recipient_onion: RecipientOnionFields,
                payment_id: PaymentId, entropy_source: &ES, node_signer: &NS, best_block_height: u32,
                send_payment_along_path: F
        ) -> Result<(), PaymentSendFailure>
        where
                ES::Target: EntropySource,
                NS::Target: NodeSigner,
-               F: Fn(&Vec<RouteHop>, &Option<PaymentParameters>, &PaymentHash, &Option<PaymentSecret>, u64,
-                  u32, PaymentId, &Option<PaymentPreimage>, [u8; 32]) -> Result<(), APIError>
+               F: Fn(SendAlongPathArgs) -> Result<(), APIError>
        {
-               let onion_session_privs = self.add_new_pending_payment(payment_hash, *payment_secret, payment_id, None, route, None, None, entropy_source, best_block_height)?;
-               self.pay_route_internal(route, payment_hash, payment_secret, None, payment_id, None,
+               let onion_session_privs = self.add_new_pending_payment(payment_hash, recipient_onion.clone(), payment_id, None, route, None, None, entropy_source, best_block_height)?;
+               self.pay_route_internal(route, payment_hash, recipient_onion, 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<R: Deref, ES: Deref, NS: Deref, IH, SP, L: Deref>(
-               &self, payment_preimage: Option<PaymentPreimage>, payment_id: PaymentId,
-               retry_strategy: Retry, route_params: RouteParameters, router: &R,
+               &self, payment_preimage: Option<PaymentPreimage>, recipient_onion: RecipientOnionFields,
+               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,
-               pending_events: &Mutex<Vec<events::Event>>, send_payment_along_path: SP
+               pending_events: &Mutex<VecDeque<(events::Event, Option<EventCompletionAction>)>>, send_payment_along_path: SP
        ) -> Result<PaymentHash, RetryableSendFailure>
        where
                R::Target: Router,
@@ -468,34 +676,36 @@ impl OutboundPayments {
                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>,
+               SP: Fn(SendAlongPathArgs) -> Result<(), APIError>,
        {
                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.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)
+               self.send_payment_internal(payment_id, payment_hash, recipient_onion, 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)
        }
 
        pub(super) fn send_spontaneous_payment_with_route<ES: Deref, NS: Deref, F>(
-               &self, route: &Route, payment_preimage: Option<PaymentPreimage>, payment_id: PaymentId,
-               entropy_source: &ES, node_signer: &NS, best_block_height: u32, send_payment_along_path: F
+               &self, route: &Route, payment_preimage: Option<PaymentPreimage>,
+               recipient_onion: RecipientOnionFields, payment_id: PaymentId, entropy_source: &ES,
+               node_signer: &NS, best_block_height: u32, send_payment_along_path: F
        ) -> Result<PaymentHash, PaymentSendFailure>
        where
                ES::Target: EntropySource,
                NS::Target: NodeSigner,
-               F: Fn(&Vec<RouteHop>, &Option<PaymentParameters>, &PaymentHash, &Option<PaymentSecret>, u64,
-                  u32, PaymentId, &Option<PaymentPreimage>, [u8; 32]) -> Result<(), APIError>
+               F: Fn(SendAlongPathArgs) -> Result<(), APIError>,
        {
                let preimage = payment_preimage
                        .unwrap_or_else(|| 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, Some(preimage), &route, None, None, entropy_source, best_block_height)?;
+               let onion_session_privs = self.add_new_pending_payment(payment_hash, recipient_onion.clone(),
+                       payment_id, Some(preimage), &route, None, None, entropy_source, best_block_height)?;
 
-               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) {
+               match self.pay_route_internal(route, payment_hash, recipient_onion, Some(preimage),
+                       payment_id, None, onion_session_privs, node_signer, best_block_height, &send_payment_along_path
+               ) {
                        Ok(()) => Ok(payment_hash),
                        Err(e) => {
                                self.remove_outbound_if_all_failed(payment_id, &e);
@@ -504,17 +714,61 @@ impl OutboundPayments {
                }
        }
 
+       #[allow(unused)]
+       pub(super) fn send_payment_for_bolt12_invoice<R: Deref, ES: Deref, NS: Deref, IH, SP, L: Deref>(
+               &self, invoice: &Bolt12Invoice, payment_id: PaymentId, router: &R,
+               first_hops: Vec<ChannelDetails>, inflight_htlcs: IH, entropy_source: &ES, node_signer: &NS,
+               best_block_height: u32, logger: &L,
+               pending_events: &Mutex<VecDeque<(events::Event, Option<EventCompletionAction>)>>,
+               send_payment_along_path: SP,
+       ) -> Result<(), Bolt12PaymentError>
+       where
+               R::Target: Router,
+               ES::Target: EntropySource,
+               NS::Target: NodeSigner,
+               L::Target: Logger,
+               IH: Fn() -> InFlightHtlcs,
+               SP: Fn(SendAlongPathArgs) -> Result<(), APIError>,
+       {
+               let payment_hash = invoice.payment_hash();
+               match self.pending_outbound_payments.lock().unwrap().entry(payment_id) {
+                       hash_map::Entry::Occupied(entry) => match entry.get() {
+                               PendingOutboundPayment::AwaitingInvoice { retry_strategy, .. } => {
+                                       *entry.into_mut() = PendingOutboundPayment::InvoiceReceived {
+                                               payment_hash,
+                                               retry_strategy: *retry_strategy,
+                                       };
+                               },
+                               _ => return Err(Bolt12PaymentError::DuplicateInvoice),
+                       },
+                       hash_map::Entry::Vacant(_) => return Err(Bolt12PaymentError::UnexpectedInvoice),
+               };
+
+               let route_params = RouteParameters {
+                       payment_params: PaymentParameters::from_bolt12_invoice(&invoice),
+                       final_value_msat: invoice.amount_msats(),
+               };
+
+               self.find_route_and_send_payment(
+                       payment_hash, payment_id, 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 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, pending_events: &Mutex<Vec<events::Event>>, logger: &L,
+               best_block_height: u32,
+               pending_events: &Mutex<VecDeque<(events::Event, Option<EventCompletionAction>)>>, 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>,
+               SP: Fn(SendAlongPathArgs) -> Result<(), APIError>,
                IH: Fn() -> InFlightHtlcs,
                FH: Fn() -> Vec<ChannelDetails>,
                L::Target: Logger,
@@ -525,38 +779,34 @@ impl OutboundPayments {
                        let mut retry_id_route_params = None;
                        for (pmt_id, pmt) in outbounds.iter_mut() {
                                if pmt.is_auto_retryable_now() {
-                                       if let PendingOutboundPayment::Retryable { pending_amt_msat, total_msat, payment_params: Some(params), .. } = pmt {
+                                       if let PendingOutboundPayment::Retryable { pending_amt_msat, total_msat, payment_params: Some(params), payment_hash, .. } = pmt {
                                                if pending_amt_msat < total_msat {
-                                                       retry_id_route_params = Some((*pmt_id, RouteParameters {
+                                                       retry_id_route_params = Some((*payment_hash, *pmt_id, RouteParameters {
                                                                final_value_msat: *total_msat - *pending_amt_msat,
-                                                               final_cltv_expiry_delta:
-                                                                       if let Some(delta) = params.final_cltv_expiry_delta { delta }
-                                                                       else {
-                                                                               debug_assert!(false, "We always set the final_cltv_expiry_delta when a path fails");
-                                                                               LDK_DEFAULT_MIN_FINAL_CLTV_EXPIRY_DELTA.into()
-                                                                       },
                                                                payment_params: params.clone(),
                                                        }));
                                                        break
                                                }
-                                       }
+                                       } else { debug_assert!(false); }
                                }
                        }
                        core::mem::drop(outbounds);
-                       if let Some((payment_id, route_params)) = retry_id_route_params {
-                               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)
+                       if let Some((payment_hash, payment_id, route_params)) = retry_id_route_params {
+                               self.find_route_and_send_payment(payment_hash, 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 }
                }
 
                let mut outbounds = self.pending_outbound_payments.lock().unwrap();
                outbounds.retain(|pmt_id, pmt| {
                        let mut retain = true;
-                       if !pmt.is_auto_retryable_now() && pmt.remaining_parts() == 0 {
-                               if pmt.mark_abandoned().is_ok() {
-                                       pending_events.lock().unwrap().push(events::Event::PaymentFailed {
+                       if !pmt.is_auto_retryable_now() && pmt.remaining_parts() == 0 && !pmt.is_awaiting_invoice() {
+                               pmt.mark_abandoned(PaymentFailureReason::RetriesExhausted);
+                               if let PendingOutboundPayment::Abandoned { payment_hash, reason, .. } = pmt {
+                                       pending_events.lock().unwrap().push_back((events::Event::PaymentFailed {
                                                payment_id: *pmt_id,
-                                               payment_hash: pmt.payment_hash().expect("PendingOutboundPayments::Retryable always has a payment hash set"),
-                                       });
+                                               payment_hash: *payment_hash,
+                                               reason: *reason,
+                                       }, None));
                                        retain = false;
                                }
                        }
@@ -567,20 +817,21 @@ impl OutboundPayments {
        pub(super) fn needs_abandon(&self) -> bool {
                let outbounds = self.pending_outbound_payments.lock().unwrap();
                outbounds.iter().any(|(_, pmt)|
-                       !pmt.is_auto_retryable_now() && pmt.remaining_parts() == 0 && !pmt.is_fulfilled())
+                       !pmt.is_auto_retryable_now() && pmt.remaining_parts() == 0 && !pmt.is_fulfilled() &&
+                       !pmt.is_awaiting_invoice())
        }
 
        /// 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
+       /// [`Event::PaymentPathFailed`]: crate::events::Event::PaymentPathFailed
+       /// [`Event::PaymentFailed`]: crate::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>,
+               &self, payment_id: PaymentId, payment_hash: PaymentHash, recipient_onion: RecipientOnionFields,
                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,
+               pending_events: &Mutex<VecDeque<(events::Event, Option<EventCompletionAction>)>>, send_payment_along_path: SP,
        ) -> Result<(), RetryableSendFailure>
        where
                R::Target: Router,
@@ -588,39 +839,50 @@ impl OutboundPayments {
                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>
+               SP: Fn(SendAlongPathArgs) -> Result<(), APIError>,
        {
                #[cfg(feature = "std")] {
                        if has_expired(&route_params) {
+                               log_error!(logger, "Payment with id {} and hash {} had expired before we started paying",
+                                       payment_id, payment_hash);
                                return Err(RetryableSendFailure::PaymentExpired)
                        }
                }
 
-               let route = router.find_route(
+               let route = router.find_route_with_id(
                        &node_signer.get_node_id(Recipient::Node).unwrap(), &route_params,
-                       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(&first_hops.iter().collect::<Vec<_>>()), inflight_htlcs(),
+                       payment_hash, payment_id,
+               ).map_err(|_| {
+                       log_error!(logger, "Failed to find route for payment with id {} and hash {}",
+                               payment_id, payment_hash);
+                       RetryableSendFailure::RouteNotFound
+               })?;
+
+               let onion_session_privs = self.add_new_pending_payment(payment_hash,
+                       recipient_onion.clone(), payment_id, keysend_preimage, &route, Some(retry_strategy),
                        Some(route_params.payment_params.clone()), entropy_source, best_block_height)
-                       .map_err(|_| RetryableSendFailure::DuplicatePayment)?;
+                       .map_err(|_| {
+                               log_error!(logger, "Payment with id {} is already pending. New payment had payment hash {}",
+                                       payment_id, payment_hash);
+                               RetryableSendFailure::DuplicatePayment
+                       })?;
 
-               let res = self.pay_route_internal(&route, payment_hash, payment_secret, None, payment_id, None,
+               let res = self.pay_route_internal(&route, payment_hash, recipient_onion, keysend_preimage, 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);
+               log_info!(logger, "Sending payment with id {} and hash {} returned {:?}",
+                       payment_id, payment_hash, 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(())
        }
 
-       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,
+       fn find_route_and_send_payment<R: Deref, NS: Deref, ES: Deref, IH, SP, L: Deref>(
+               &self, payment_hash: PaymentHash, 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<VecDeque<(events::Event, Option<EventCompletionAction>)>>, send_payment_along_path: &SP,
        )
        where
                R::Target: Router,
@@ -628,74 +890,119 @@ impl OutboundPayments {
                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>
+               SP: Fn(SendAlongPathArgs) -> Result<(), APIError>,
        {
                #[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);
+                               log_error!(logger, "Payment params expired on retry, abandoning payment {}", &payment_id);
+                               self.abandon_payment(payment_id, PaymentFailureReason::PaymentExpired, pending_events);
                                return
                        }
                }
 
-               let route = match router.find_route(
+               let route = match router.find_route_with_id(
                        &node_signer.get_node_id(Recipient::Node).unwrap(), &route_params,
-                       Some(&first_hops.iter().collect::<Vec<_>>()), &inflight_htlcs()
+                       Some(&first_hops.iter().collect::<Vec<_>>()), inflight_htlcs(),
+                       payment_hash, payment_id,
                ) {
                        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);
+                               log_error!(logger, "Failed to find a route on retry, abandoning payment {}: {:#?}", &payment_id, e);
+                               self.abandon_payment(payment_id, PaymentFailureReason::RouteNotFound, pending_events);
                                return
                        }
                };
                for path in route.paths.iter() {
-                       if path.len() == 0 {
-                               log_error!(logger, "length-0 path in route");
-                               self.abandon_payment(payment_id, pending_events);
+                       if path.hops.len() == 0 {
+                               log_error!(logger, "Unusable path in route (path.hops.len() must be at least 1");
+                               self.abandon_payment(payment_id, PaymentFailureReason::UnexpectedError, 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,
-                                       });
-                                       $payment.remove();
+                       ($payment: expr, $reason: expr) => {
+                               $payment.get_mut().mark_abandoned($reason);
+                               if let PendingOutboundPayment::Abandoned { reason, .. } = $payment.get() {
+                                       if $payment.get().remaining_parts() == 0 {
+                                               pending_events.lock().unwrap().push_back((events::Event::PaymentFailed {
+                                                       payment_id,
+                                                       payment_hash,
+                                                       reason: *reason,
+                                               }, None));
+                                               $payment.remove();
+                                       }
                                }
                        }
                }
-               let (total_msat, payment_hash, payment_secret, keysend_preimage) = {
+               let (total_msat, recipient_onion, keysend_preimage, onion_session_privs) = {
                        let mut outbounds = self.pending_outbound_payments.lock().unwrap();
                        match outbounds.entry(payment_id) {
                                hash_map::Entry::Occupied(mut payment) => {
-                                       let res = match payment.get() {
+                                       match payment.get() {
                                                PendingOutboundPayment::Retryable {
-                                                       total_msat, payment_hash, keysend_preimage, payment_secret, pending_amt_msat, ..
+                                                       total_msat, keysend_preimage, payment_secret, payment_metadata,
+                                                       custom_tlvs, pending_amt_msat, ..
                                                } => {
-                                                       let retry_amt_msat: u64 = route.paths.iter().map(|path| path.last().unwrap().fee_msat).sum();
+                                                       const RETRY_OVERFLOW_PERCENTAGE: u64 = 10;
+                                                       let retry_amt_msat = route.get_total_amount();
                                                        if retry_amt_msat + *pending_amt_msat > *total_msat * (100 + RETRY_OVERFLOW_PERCENTAGE) / 100 {
                                                                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);
+                                                               abandon_with_entry!(payment, PaymentFailureReason::UnexpectedError);
+                                                               return
+                                                       }
+
+                                                       if !payment.get().is_retryable_now() {
+                                                               log_error!(logger, "Retries exhausted for payment id {}", &payment_id);
+                                                               abandon_with_entry!(payment, PaymentFailureReason::RetriesExhausted);
                                                                return
                                                        }
-                                                       (*total_msat, *payment_hash, *payment_secret, *keysend_preimage)
+
+                                                       let total_msat = *total_msat;
+                                                       let recipient_onion = RecipientOnionFields {
+                                                               payment_secret: *payment_secret,
+                                                               payment_metadata: payment_metadata.clone(),
+                                                               custom_tlvs: custom_tlvs.clone(),
+                                                       };
+                                                       let keysend_preimage = *keysend_preimage;
+
+                                                       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());
+                                                       }
+
+                                                       for (path, session_priv_bytes) in route.paths.iter().zip(onion_session_privs.iter()) {
+                                                               assert!(payment.get_mut().insert(*session_priv_bytes, path));
+                                                       }
+
+                                                       payment.get_mut().increment_attempts();
+
+                                                       (total_msat, recipient_onion, keysend_preimage, onion_session_privs)
                                                },
                                                PendingOutboundPayment::Legacy { .. } => {
                                                        log_error!(logger, "Unable to retry payments that were initially sent on LDK versions prior to 0.0.102");
                                                        return
                                                },
+                                               PendingOutboundPayment::AwaitingInvoice { .. } => {
+                                                       log_error!(logger, "Payment not yet sent");
+                                                       return
+                                               },
+                                               PendingOutboundPayment::InvoiceReceived { payment_hash, retry_strategy } => {
+                                                       let total_amount = route_params.final_value_msat;
+                                                       let recipient_onion = RecipientOnionFields {
+                                                               payment_secret: None,
+                                                               payment_metadata: None,
+                                                               custom_tlvs: vec![],
+                                                       };
+                                                       let retry_strategy = Some(*retry_strategy);
+                                                       let payment_params = Some(route_params.payment_params.clone());
+                                                       let (retryable_payment, onion_session_privs) = self.create_pending_payment(
+                                                               *payment_hash, recipient_onion.clone(), None, &route,
+                                                               retry_strategy, payment_params, entropy_source, best_block_height
+                                                       );
+                                                       *payment.into_mut() = retryable_payment;
+                                                       (total_amount, recipient_onion, None, onion_session_privs)
+                                               },
                                                PendingOutboundPayment::Fulfilled { .. } => {
                                                        log_error!(logger, "Payment already completed");
                                                        return
@@ -704,28 +1011,18 @@ impl OutboundPayments {
                                                        log_error!(logger, "Payment already abandoned (with some HTLCs still pending)");
                                                        return
                                                },
-                                       };
-                                       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.get_mut().increment_attempts();
-                                       for (path, session_priv_bytes) in route.paths.iter().zip(onion_session_privs.iter()) {
-                                               assert!(payment.get_mut().insert(*session_priv_bytes, path));
                                        }
-                                       res
                                },
                                hash_map::Entry::Vacant(_) => {
-                                       log_error!(logger, "Payment with ID {} not found", log_bytes!(payment_id.0));
+                                       log_error!(logger, "Payment with ID {} not found", &payment_id);
                                        return
                                }
                        }
                };
-               let res = self.pay_route_internal(&route, payment_hash, &payment_secret, keysend_preimage,
+               let res = self.pay_route_internal(&route, payment_hash, recipient_onion, 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);
+               log_info!(logger, "Result retrying payment id {}: {:?}", &payment_id, 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);
                }
@@ -735,7 +1032,7 @@ impl OutboundPayments {
                &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,
+               pending_events: &Mutex<VecDeque<(events::Event, Option<EventCompletionAction>)>>, send_payment_along_path: &SP,
        )
        where
                R::Target: Router,
@@ -743,20 +1040,19 @@ impl OutboundPayments {
                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>
+               SP: Fn(SendAlongPathArgs) -> 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);
+                               Self::push_path_failed_evs_and_scids(payment_id, payment_hash, &mut route_params, route.paths, errs.into_iter().map(|e| Err(e)), logger, pending_events);
+                               self.find_route_and_send_payment(payment_hash, 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);
+                               Self::push_path_failed_evs_and_scids(payment_id, payment_hash, &mut retry, route.paths, results.into_iter(), logger, 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);
+                               self.find_route_and_send_payment(payment_hash, 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
@@ -764,74 +1060,79 @@ impl OutboundPayments {
                                // 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);
+                               log_error!(logger, "Failed to send to route due to parameter error in a single path. Your router is buggy");
+                               Self::push_path_failed_evs_and_scids(payment_id, payment_hash, &mut route_params, route.paths, results.into_iter(), logger, pending_events);
+                               self.abandon_payment(payment_id, PaymentFailureReason::UnexpectedError, 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);
+                               self.abandon_payment(payment_id, PaymentFailureReason::UnexpectedError, pending_events);
                        },
                        PaymentSendFailure::DuplicatePayment => debug_assert!(false), // unreachable
                }
        }
 
-       fn push_path_failed_evs_and_scids<I: ExactSizeIterator + Iterator<Item = Result<(), APIError>>>(
+       fn push_path_failed_evs_and_scids<I: ExactSizeIterator + Iterator<Item = Result<(), APIError>>, L: Deref>(
                payment_id: PaymentId, payment_hash: PaymentHash, route_params: &mut RouteParameters,
-               paths: Vec<Vec<RouteHop>>, path_results: I, pending_events: &Mutex<Vec<events::Event>>
-       ) {
+               paths: Vec<Path>, path_results: I, logger: &L,
+               pending_events: &Mutex<VecDeque<(events::Event, Option<EventCompletionAction>)>>,
+       ) where L::Target: Logger {
                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;
+                               if let APIError::MonitorUpdateInProgress = e { continue }
+                               log_error!(logger, "Failed to send along path due to error: {:?}", e);
+                               let mut failed_scid = None;
+                               if let APIError::ChannelUnavailable { .. } = e {
+                                       let scid = path.hops[0].short_channel_id;
+                                       failed_scid = Some(scid);
                                        route_params.payment_params.previously_failed_channels.push(scid);
-                                       Some(scid)
-                               };
-                               events.push(events::Event::PaymentPathFailed {
+                               }
+                               events.push_back((events::Event::PaymentPathFailed {
                                        payment_id: Some(payment_id),
                                        payment_hash,
                                        payment_failed_permanently: false,
-                                       network_update: None,
-                                       all_paths_failed: false,
+                                       failure: events::PathFailure::InitialSend { err: e },
                                        path,
                                        short_channel_id: failed_scid,
-                                       retry: None,
                                        #[cfg(test)]
                                        error_code: None,
                                        #[cfg(test)]
                                        error_data: None,
-                               });
+                               }, None));
                        }
                }
        }
 
        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
+               &self, path: Path, 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
                ES::Target: EntropySource,
                NS::Target: NodeSigner,
-               F: Fn(&Vec<RouteHop>, &Option<PaymentParameters>, &PaymentHash, &Option<PaymentSecret>, u64,
-                  u32, PaymentId, &Option<PaymentPreimage>, [u8; 32]) -> Result<(), APIError>
+               F: Fn(SendAlongPathArgs) -> Result<(), APIError>,
        {
                let payment_id = PaymentId(entropy_source.get_secure_random_bytes());
+               let payment_secret = PaymentSecret(entropy_source.get_secure_random_bytes());
 
                let payment_hash = probing_cookie_from_id(&payment_id, probing_cookie_secret);
 
-               if hops.len() < 2 {
+               if path.hops.len() < 2 && path.blinded_tail.is_none() {
                        return Err(PaymentSendFailure::ParameterError(APIError::APIMisuseError {
                                err: "No need probing a path with less than two hops".to_string()
                        }))
                }
 
-               let route = Route { paths: vec![hops], payment_params: None };
-               let onion_session_privs = self.add_new_pending_payment(payment_hash, None, payment_id, None, &route, None, None, entropy_source, best_block_height)?;
+               let route = Route { paths: vec![path], route_params: None };
+               let onion_session_privs = self.add_new_pending_payment(payment_hash,
+                       RecipientOnionFields::secret_only(payment_secret), payment_id, None, &route, None, None,
+                       entropy_source, best_block_height)?;
 
-               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) {
+               match self.pay_route_internal(&route, payment_hash, RecipientOnionFields::spontaneous_empty(),
+                       None, payment_id, None, onion_session_privs, node_signer, best_block_height, &send_payment_along_path
+               ) {
                        Ok(()) => Ok((payment_hash, payment_id)),
                        Err(e) => {
                                self.remove_outbound_if_all_failed(payment_id, &e);
@@ -840,98 +1141,151 @@ impl OutboundPayments {
                }
        }
 
+       #[cfg(test)]
+       pub(super) fn test_set_payment_metadata(
+               &self, payment_id: PaymentId, new_payment_metadata: Option<Vec<u8>>
+       ) {
+               match self.pending_outbound_payments.lock().unwrap().get_mut(&payment_id).unwrap() {
+                       PendingOutboundPayment::Retryable { payment_metadata, .. } => {
+                               *payment_metadata = new_payment_metadata;
+                       },
+                       _ => panic!("Need a retryable payment to update metadata on"),
+               }
+       }
+
        #[cfg(test)]
        pub(super) fn test_add_new_pending_payment<ES: Deref>(
-               &self, payment_hash: PaymentHash, payment_secret: Option<PaymentSecret>, payment_id: PaymentId,
+               &self, payment_hash: PaymentHash, recipient_onion: RecipientOnionFields, payment_id: PaymentId,
                route: &Route, retry_strategy: Option<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, None, route, retry_strategy, None, entropy_source, best_block_height)
+               self.add_new_pending_payment(payment_hash, recipient_onion, payment_id, None, 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,
+               &self, payment_hash: PaymentHash, recipient_onion: RecipientOnionFields, payment_id: PaymentId,
                keysend_preimage: Option<PaymentPreimage>, route: &Route, retry_strategy: Option<Retry>,
                payment_params: Option<PaymentParameters>, entropy_source: &ES, best_block_height: u32
        ) -> Result<Vec<[u8; 32]>, PaymentSendFailure> where ES::Target: EntropySource {
+               let mut pending_outbounds = self.pending_outbound_payments.lock().unwrap();
+               match pending_outbounds.entry(payment_id) {
+                       hash_map::Entry::Occupied(_) => Err(PaymentSendFailure::DuplicatePayment),
+                       hash_map::Entry::Vacant(entry) => {
+                               let (payment, onion_session_privs) = self.create_pending_payment(
+                                       payment_hash, recipient_onion, keysend_preimage, route, retry_strategy,
+                                       payment_params, entropy_source, best_block_height
+                               );
+                               entry.insert(payment);
+                               Ok(onion_session_privs)
+                       },
+               }
+       }
+
+       fn create_pending_payment<ES: Deref>(
+               &self, payment_hash: PaymentHash, recipient_onion: RecipientOnionFields,
+               keysend_preimage: Option<PaymentPreimage>, route: &Route, retry_strategy: Option<Retry>,
+               payment_params: Option<PaymentParameters>, entropy_source: &ES, best_block_height: u32
+       ) -> (PendingOutboundPayment, Vec<[u8; 32]>)
+       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(entropy_source.get_secure_random_bytes());
                }
 
+               let mut payment = PendingOutboundPayment::Retryable {
+                       retry_strategy,
+                       attempts: PaymentAttempts::new(),
+                       payment_params,
+                       session_privs: HashSet::new(),
+                       pending_amt_msat: 0,
+                       pending_fee_msat: Some(0),
+                       payment_hash,
+                       payment_secret: recipient_onion.payment_secret,
+                       payment_metadata: recipient_onion.payment_metadata,
+                       keysend_preimage,
+                       custom_tlvs: recipient_onion.custom_tlvs,
+                       starting_block_height: best_block_height,
+                       total_msat: route.get_total_amount(),
+               };
+
+               for (path, session_priv_bytes) in route.paths.iter().zip(onion_session_privs.iter()) {
+                       assert!(payment.insert(*session_priv_bytes, path));
+               }
+
+               (payment, onion_session_privs)
+       }
+
+       #[allow(unused)]
+       pub(super) fn add_new_awaiting_invoice(
+               &self, payment_id: PaymentId, retry_strategy: Retry
+       ) -> Result<(), ()> {
                let mut pending_outbounds = self.pending_outbound_payments.lock().unwrap();
                match pending_outbounds.entry(payment_id) {
-                       hash_map::Entry::Occupied(_) => Err(PaymentSendFailure::DuplicatePayment),
+                       hash_map::Entry::Occupied(_) => Err(()),
                        hash_map::Entry::Vacant(entry) => {
-                               let payment = entry.insert(PendingOutboundPayment::Retryable {
+                               entry.insert(PendingOutboundPayment::AwaitingInvoice {
+                                       timer_ticks_without_response: 0,
                                        retry_strategy,
-                                       attempts: PaymentAttempts::new(),
-                                       payment_params,
-                                       session_privs: HashSet::new(),
-                                       pending_amt_msat: 0,
-                                       pending_fee_msat: Some(0),
-                                       payment_hash,
-                                       payment_secret,
-                                       keysend_preimage,
-                                       starting_block_height: best_block_height,
-                                       total_msat: route.get_total_amount(),
                                });
 
-                               for (path, session_priv_bytes) in route.paths.iter().zip(onion_session_privs.iter()) {
-                                       assert!(payment.insert(*session_priv_bytes, path));
-                               }
-
-                               Ok(onion_session_privs)
+                               Ok(())
                        },
                }
        }
 
        fn pay_route_internal<NS: Deref, F>(
-               &self, route: &Route, payment_hash: PaymentHash, payment_secret: &Option<PaymentSecret>,
+               &self, route: &Route, payment_hash: PaymentHash, recipient_onion: RecipientOnionFields,
                keysend_preimage: Option<PaymentPreimage>, payment_id: PaymentId, recv_value_msat: Option<u64>,
                onion_session_privs: Vec<[u8; 32]>, node_signer: &NS, best_block_height: u32,
                send_payment_along_path: &F
        ) -> Result<(), PaymentSendFailure>
        where
                NS::Target: NodeSigner,
-               F: Fn(&Vec<RouteHop>, &Option<PaymentParameters>, &PaymentHash, &Option<PaymentSecret>, u64,
-                  u32, PaymentId, &Option<PaymentPreimage>, [u8; 32]) -> Result<(), APIError>
+               F: Fn(SendAlongPathArgs) -> Result<(), APIError>,
        {
                if route.paths.len() < 1 {
-                       return Err(PaymentSendFailure::ParameterError(APIError::InvalidRoute{err: "There must be at least one path to send over"}));
+                       return Err(PaymentSendFailure::ParameterError(APIError::InvalidRoute{err: "There must be at least one path to send over".to_owned()}));
                }
-               if payment_secret.is_none() && route.paths.len() > 1 {
-                       return Err(PaymentSendFailure::ParameterError(APIError::APIMisuseError{err: "Payment secret is required for multi-path payments".to_string()}));
+               if recipient_onion.payment_secret.is_none() && route.paths.len() > 1
+                       && !route.paths.iter().any(|p| p.blinded_tail.is_some())
+               {
+                       return Err(PaymentSendFailure::ParameterError(APIError::APIMisuseError{err: "Payment secret is required for multi-path payments".to_owned()}));
                }
                let mut total_value = 0;
                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 {
-                               path_errs.push(Err(APIError::InvalidRoute{err: "Path didn't go anywhere/had bogus size"}));
+                       if path.hops.len() < 1 || path.hops.len() > 20 {
+                               path_errs.push(Err(APIError::InvalidRoute{err: "Path didn't go anywhere/had bogus size".to_owned()}));
                                continue 'path_check;
                        }
-                       for (idx, hop) in path.iter().enumerate() {
-                               if idx != path.len() - 1 && hop.pubkey == our_node_id {
-                                       path_errs.push(Err(APIError::InvalidRoute{err: "Path went through us but wasn't a simple rebalance loop to us"}));
+                       let dest_hop_idx = if path.blinded_tail.is_some() && path.blinded_tail.as_ref().unwrap().hops.len() > 1 {
+                               usize::max_value() } else { path.hops.len() - 1 };
+                       for (idx, hop) in path.hops.iter().enumerate() {
+                               if idx != dest_hop_idx && hop.pubkey == our_node_id {
+                                       path_errs.push(Err(APIError::InvalidRoute{err: "Path went through us but wasn't a simple rebalance loop to us".to_owned()}));
                                        continue 'path_check;
                                }
                        }
-                       total_value += path.last().unwrap().fee_msat;
+                       total_value += path.final_value_msat();
                        path_errs.push(Ok(()));
                }
                if path_errs.iter().any(|e| e.is_err()) {
                        return Err(PaymentSendFailure::PathParameterError(path_errs));
                }
                if let Some(amt_msat) = recv_value_msat {
-                       debug_assert!(amt_msat >= total_value);
                        total_value = amt_msat;
                }
 
                let cur_height = best_block_height + 1;
                let mut results = Vec::new();
                debug_assert_eq!(route.paths.len(), onion_session_privs.len());
-               for (path, session_priv) in route.paths.iter().zip(onion_session_privs.into_iter()) {
-                       let mut path_res = send_payment_along_path(&path, &route.payment_params, &payment_hash, payment_secret, total_value, cur_height, payment_id, &keysend_preimage, session_priv);
+               for (path, session_priv_bytes) in route.paths.iter().zip(onion_session_privs.into_iter()) {
+                       let mut path_res = send_payment_along_path(SendAlongPathArgs {
+                               path: &path, payment_hash: &payment_hash, recipient_onion: recipient_onion.clone(),
+                               total_value, cur_height, payment_id, keysend_preimage: &keysend_preimage, session_priv_bytes
+                       });
                        match path_res {
                                Ok(_) => {},
                                Err(APIError::MonitorUpdateInProgress) => {
@@ -942,7 +1296,7 @@ impl OutboundPayments {
                                Err(_) => {
                                        let mut pending_outbounds = self.pending_outbound_payments.lock().unwrap();
                                        if let Some(payment) = pending_outbounds.get_mut(&payment_id) {
-                                               let removed = payment.remove(&session_priv, Some(path));
+                                               let removed = payment.remove(&session_priv_bytes, Some(path));
                                                debug_assert!(removed, "This can't happen as the payment has an entry for this path added by callers");
                                        } else {
                                                debug_assert!(false, "This can't happen as the payment was added by callers");
@@ -955,7 +1309,6 @@ impl OutboundPayments {
                let mut has_ok = false;
                let mut has_err = false;
                let mut pending_amt_unsent = 0;
-               let mut max_unsent_cltv_delta = 0;
                for (res, path) in results.iter().zip(route.paths.iter()) {
                        if res.is_ok() { has_ok = true; }
                        if res.is_err() { has_err = true; }
@@ -965,8 +1318,7 @@ impl OutboundPayments {
                                has_err = true;
                                has_ok = true;
                        } else if res.is_err() {
-                               pending_amt_unsent += path.last().unwrap().fee_msat;
-                               max_unsent_cltv_delta = cmp::max(max_unsent_cltv_delta, path.last().unwrap().cltv_expiry_delta);
+                               pending_amt_unsent += path.final_value_msat();
                        }
                }
                if has_err && has_ok {
@@ -974,13 +1326,10 @@ impl OutboundPayments {
                                results,
                                payment_id,
                                failed_paths_retry: if pending_amt_unsent != 0 {
-                                       if let Some(payment_params) = &route.payment_params {
+                                       if let Some(payment_params) = route.route_params.as_ref().map(|p| p.payment_params.clone()) {
                                                Some(RouteParameters {
-                                                       payment_params: payment_params.clone(),
+                                                       payment_params: payment_params,
                                                        final_value_msat: pending_amt_unsent,
-                                                       final_cltv_expiry_delta:
-                                                               if let Some(delta) = payment_params.final_cltv_expiry_delta { delta }
-                                                               else { max_unsent_cltv_delta },
                                                })
                                        } else { None }
                                } else { None },
@@ -994,17 +1343,16 @@ impl OutboundPayments {
 
        #[cfg(test)]
        pub(super) fn test_send_payment_internal<NS: Deref, F>(
-               &self, route: &Route, payment_hash: PaymentHash, payment_secret: &Option<PaymentSecret>,
+               &self, route: &Route, payment_hash: PaymentHash, recipient_onion: RecipientOnionFields,
                keysend_preimage: Option<PaymentPreimage>, payment_id: PaymentId, recv_value_msat: Option<u64>,
                onion_session_privs: Vec<[u8; 32]>, node_signer: &NS, best_block_height: u32,
                send_payment_along_path: F
        ) -> Result<(), PaymentSendFailure>
        where
                NS::Target: NodeSigner,
-               F: Fn(&Vec<RouteHop>, &Option<PaymentParameters>, &PaymentHash, &Option<PaymentSecret>, u64,
-                  u32, PaymentId, &Option<PaymentPreimage>, [u8; 32]) -> Result<(), APIError>
+               F: Fn(SendAlongPathArgs) -> Result<(), APIError>,
        {
-               self.pay_route_internal(route, payment_hash, payment_secret, keysend_preimage, payment_id,
+               self.pay_route_internal(route, payment_hash, recipient_onion, 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 })
@@ -1021,7 +1369,9 @@ impl OutboundPayments {
 
        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
+               path: Path, from_onchain: bool, ev_completion_action: EventCompletionAction,
+               pending_events: &Mutex<VecDeque<(events::Event, Option<EventCompletionAction>)>>,
+               logger: &L,
        ) where L::Target: Logger {
                let mut session_priv_bytes = [0; 32];
                session_priv_bytes.copy_from_slice(&session_priv[..]);
@@ -1030,15 +1380,14 @@ impl OutboundPayments {
                if let hash_map::Entry::Occupied(mut payment) = outbounds.entry(payment_id) {
                        if !payment.get().is_fulfilled() {
                                let payment_hash = PaymentHash(Sha256::hash(&payment_preimage.0).into_inner());
+                               log_info!(logger, "Payment with id {} and hash {} sent!", payment_id, payment_hash);
                                let fee_paid_msat = payment.get().get_pending_fee_msat();
-                               pending_events.push(
-                                       events::Event::PaymentSent {
-                                               payment_id: Some(payment_id),
-                                               payment_preimage,
-                                               payment_hash,
-                                               fee_paid_msat,
-                                       }
-                               );
+                               pending_events.push_back((events::Event::PaymentSent {
+                                       payment_id: Some(payment_id),
+                                       payment_preimage,
+                                       payment_hash,
+                                       fee_paid_msat,
+                               }, Some(ev_completion_action.clone())));
                                payment.get_mut().mark_fulfilled();
                        }
 
@@ -1051,21 +1400,21 @@ impl OutboundPayments {
                                // irrevocably fulfilled.
                                if payment.get_mut().remove(&session_priv_bytes, Some(&path)) {
                                        let payment_hash = Some(PaymentHash(Sha256::hash(&payment_preimage.0).into_inner()));
-                                       pending_events.push(
-                                               events::Event::PaymentPathSuccessful {
-                                                       payment_id,
-                                                       payment_hash,
-                                                       path,
-                                               }
-                                       );
+                                       pending_events.push_back((events::Event::PaymentPathSuccessful {
+                                               payment_id,
+                                               payment_hash,
+                                               path,
+                                       }, Some(ev_completion_action)));
                                }
                        }
                } else {
-                       log_trace!(logger, "Received duplicative fulfill for HTLC with payment_preimage {}", log_bytes!(payment_preimage.0));
+                       log_trace!(logger, "Received duplicative fulfill for HTLC with payment_preimage {}", &payment_preimage);
                }
        }
 
-       pub(super) fn finalize_claims(&self, sources: Vec<HTLCSource>, pending_events: &Mutex<Vec<events::Event>>) {
+       pub(super) fn finalize_claims(&self, sources: Vec<HTLCSource>,
+               pending_events: &Mutex<VecDeque<(events::Event, Option<EventCompletionAction>)>>)
+       {
                let mut outbounds = self.pending_outbound_payments.lock().unwrap();
                let mut pending_events = pending_events.lock().unwrap();
                for source in sources {
@@ -1075,34 +1424,36 @@ impl OutboundPayments {
                                if let hash_map::Entry::Occupied(mut payment) = outbounds.entry(payment_id) {
                                        assert!(payment.get().is_fulfilled());
                                        if payment.get_mut().remove(&session_priv_bytes, None) {
-                                               pending_events.push(
-                                                       events::Event::PaymentPathSuccessful {
-                                                               payment_id,
-                                                               payment_hash: payment.get().payment_hash(),
-                                                               path,
-                                                       }
-                                               );
+                                               let payment_hash = payment.get().payment_hash();
+                                               debug_assert!(payment_hash.is_some());
+                                               pending_events.push_back((events::Event::PaymentPathSuccessful {
+                                                       payment_id,
+                                                       payment_hash,
+                                                       path,
+                                               }, None));
                                        }
                                }
                        }
                }
        }
 
-       pub(super) fn remove_stale_resolved_payments(&self, pending_events: &Mutex<Vec<events::Event>>) {
-               // If an outbound payment was completed, and no pending HTLCs remain, we should remove it
-               // from the map. However, if we did that immediately when the last payment HTLC is claimed,
-               // this could race the user making a duplicate send_payment call and our idempotency
-               // guarantees would be violated. Instead, we wait a few timer ticks to do the actual
-               // removal. This should be more than sufficient to ensure the idempotency of any
-               // `send_payment` calls that were made at the same time the `PaymentSent` event was being
-               // processed.
+       pub(super) fn remove_stale_payments(
+               &self, pending_events: &Mutex<VecDeque<(events::Event, Option<EventCompletionAction>)>>)
+       {
                let mut pending_outbound_payments = self.pending_outbound_payments.lock().unwrap();
-               let pending_events = pending_events.lock().unwrap();
+               let mut pending_events = pending_events.lock().unwrap();
                pending_outbound_payments.retain(|payment_id, payment| {
+                       // If an outbound payment was completed, and no pending HTLCs remain, we should remove it
+                       // from the map. However, if we did that immediately when the last payment HTLC is claimed,
+                       // this could race the user making a duplicate send_payment call and our idempotency
+                       // guarantees would be violated. Instead, we wait a few timer ticks to do the actual
+                       // removal. This should be more than sufficient to ensure the idempotency of any
+                       // `send_payment` calls that were made at the same time the `PaymentSent` event was being
+                       // processed.
                        if let PendingOutboundPayment::Fulfilled { session_privs, timer_ticks_without_htlcs, .. } = payment {
                                let mut no_remaining_entries = session_privs.is_empty();
                                if no_remaining_entries {
-                                       for ev in pending_events.iter() {
+                                       for (ev, _) in pending_events.iter() {
                                                match ev {
                                                        events::Event::PaymentSent { payment_id: Some(ev_payment_id), .. } |
                                                                events::Event::PaymentPathSuccessful { payment_id: ev_payment_id, .. } |
@@ -1123,6 +1474,16 @@ impl OutboundPayments {
                                        *timer_ticks_without_htlcs = 0;
                                        true
                                }
+                       } else if let PendingOutboundPayment::AwaitingInvoice { timer_ticks_without_response, .. } = payment {
+                               *timer_ticks_without_response += 1;
+                               if *timer_ticks_without_response <= INVOICE_REQUEST_TIMEOUT_TICKS {
+                                       true
+                               } else {
+                                       pending_events.push_back(
+                                               (events::Event::InvoiceRequestFailed { payment_id: *payment_id }, None)
+                                       );
+                                       false
+                               }
                        } else { true }
                });
        }
@@ -1130,14 +1491,17 @@ impl OutboundPayments {
        // Returns a bool indicating whether a PendingHTLCsForwardable event should be generated.
        pub(super) fn fail_htlc<L: Deref>(
                &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
+               path: &Path, session_priv: &SecretKey, payment_id: &PaymentId,
+               probing_cookie_secret: [u8; 32], secp_ctx: &Secp256k1<secp256k1::All>,
+               pending_events: &Mutex<VecDeque<(events::Event, Option<EventCompletionAction>)>>, logger: &L,
        ) -> bool 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);
+               let DecodedOnionFailure {
+                       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 DecodedOnionFailure { network_update, short_channel_id, payment_retryable } =
+                       onion_error.decode_onion_failure(secp_ctx, logger, &source);
 
                let payment_is_probe = payment_is_probe(payment_hash, &payment_id, probing_cookie_secret);
                let mut session_priv_bytes = [0; 32];
@@ -1158,61 +1522,41 @@ impl OutboundPayments {
                        awaiting_retry
                });
 
-               let mut all_paths_failed = false;
                let mut full_failure_ev = None;
                let mut pending_retry_ev = false;
-               let mut retry = 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));
+                               log_trace!(logger, "Received duplicative fail for HTLC with payment_hash {}", &payment_hash);
                                return false
                        }
                        if payment.get().is_fulfilled() {
-                               log_trace!(logger, "Received failure of HTLC with payment_hash {} after payment completion", log_bytes!(payment_hash.0));
+                               log_trace!(logger, "Received failure of HTLC with payment_hash {} after payment completion", &payment_hash);
                                return false
                        }
                        let mut is_retryable_now = payment.get().is_auto_retryable_now();
                        if let Some(scid) = short_channel_id {
+                               // TODO: If we decided to blame ourselves (or one of our channels) in
+                               // process_onion_failure we should close that channel as it implies our
+                               // next-hop is needlessly blaming us!
                                payment.get_mut().insert_previously_failed_scid(scid);
                        }
 
-                       // We want to move towards only using the `PaymentParameters` in the outbound payments
-                       // map. However, for backwards-compatibility, we still need to support passing the
-                       // `PaymentParameters` data that was shoved in the HTLC (and given to us via
-                       // `payment_params`) back to the user.
-                       let path_last_hop = path.last().expect("Outbound payments must have had a valid path");
-                       if let Some(params) = payment.get_mut().payment_parameters() {
-                               if params.final_cltv_expiry_delta.is_none() {
-                                       // This should be rare, but a user could provide None for the payment data, and
-                                       // we need it when we go to retry the payment, so fill it in.
-                                       params.final_cltv_expiry_delta = Some(path_last_hop.cltv_expiry_delta);
-                               }
-                               retry = Some(RouteParameters {
-                                       payment_params: params.clone(),
-                                       final_value_msat: path_last_hop.fee_msat,
-                                       final_cltv_expiry_delta: params.final_cltv_expiry_delta.unwrap(),
-                               });
-                       } else if let Some(params) = payment_params {
-                               retry = Some(RouteParameters {
-                                       payment_params: params.clone(),
-                                       final_value_msat: path_last_hop.fee_msat,
-                                       final_cltv_expiry_delta:
-                                               if let Some(delta) = params.final_cltv_expiry_delta { delta }
-                                               else { path_last_hop.cltv_expiry_delta },
-                               });
-                       }
-
-                       if payment_is_probe || !is_retryable_now || !payment_retryable || retry.is_none() {
-                               let _ = payment.get_mut().mark_abandoned(); // we'll only Err if it's a legacy payment
+                       if payment_is_probe || !is_retryable_now || !payment_retryable {
+                               let reason = if !payment_retryable {
+                                       PaymentFailureReason::RecipientRejected
+                               } else {
+                                       PaymentFailureReason::RetriesExhausted
+                               };
+                               payment.get_mut().mark_abandoned(reason);
                                is_retryable_now = false;
                        }
                        if payment.get().remaining_parts() == 0 {
-                               all_paths_failed = true;
-                               if payment.get().abandoned() {
+                               if let PendingOutboundPayment::Abandoned { payment_hash, reason, .. }= payment.get() {
                                        if !payment_is_probe {
                                                full_failure_ev = Some(events::Event::PaymentFailed {
                                                        payment_id: *payment_id,
-                                                       payment_hash: payment.get().payment_hash().expect("PendingOutboundPayments::RetriesExceeded always has a payment hash set"),
+                                                       payment_hash: *payment_hash,
+                                                       reason: *reason,
                                                });
                                        }
                                        payment.remove();
@@ -1220,11 +1564,11 @@ impl OutboundPayments {
                        }
                        is_retryable_now
                } else {
-                       log_trace!(logger, "Received duplicative fail for HTLC with payment_hash {}", log_bytes!(payment_hash.0));
+                       log_trace!(logger, "Received duplicative fail for HTLC with payment_hash {}", &payment_hash);
                        return false
                };
                core::mem::drop(outbounds);
-               log_trace!(logger, "Failing outbound payment HTLC with payment_hash {}", log_bytes!(payment_hash.0));
+               log_trace!(logger, "Failing outbound payment HTLC with payment_hash {}", &payment_hash);
 
                let path_failure = {
                        if payment_is_probe {
@@ -1243,12 +1587,6 @@ impl OutboundPayments {
                                        }
                                }
                        } else {
-                               // TODO: If we decided to blame ourselves (or one of our channels) in
-                               // process_onion_failure we should close that channel as it implies our
-                               // next-hop is needlessly blaming us!
-                               if let Some(scid) = short_channel_id {
-                                       retry.as_mut().map(|r| r.payment_params.previously_failed_channels.push(scid));
-                               }
                                // If we miss abandoning the payment above, we *must* generate an event here or else the
                                // payment will sit in our outbounds forever.
                                if attempts_remaining && !already_awaiting_retry {
@@ -1259,11 +1597,9 @@ impl OutboundPayments {
                                        payment_id: Some(*payment_id),
                                        payment_hash: payment_hash.clone(),
                                        payment_failed_permanently: !payment_retryable,
-                                       network_update,
-                                       all_paths_failed,
+                                       failure: events::PathFailure::OnPath { network_update },
                                        path: path.clone(),
                                        short_channel_id,
-                                       retry,
                                        #[cfg(test)]
                                        error_code: onion_error_code,
                                        #[cfg(test)]
@@ -1272,24 +1608,32 @@ 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); }
+               pending_events.push_back((path_failure, None));
+               if let Some(ev) = full_failure_ev { pending_events.push_back((ev, None)); }
                pending_retry_ev
        }
 
        pub(super) fn abandon_payment(
-               &self, payment_id: PaymentId, pending_events: &Mutex<Vec<events::Event>>
+               &self, payment_id: PaymentId, reason: PaymentFailureReason,
+               pending_events: &Mutex<VecDeque<(events::Event, Option<EventCompletionAction>)>>
        ) {
                let mut outbounds = self.pending_outbound_payments.lock().unwrap();
                if let hash_map::Entry::Occupied(mut payment) = outbounds.entry(payment_id) {
-                       if let Ok(()) = payment.get_mut().mark_abandoned() {
+                       payment.get_mut().mark_abandoned(reason);
+                       if let PendingOutboundPayment::Abandoned { payment_hash, reason, .. } = payment.get() {
                                if payment.get().remaining_parts() == 0 {
-                                       pending_events.lock().unwrap().push(events::Event::PaymentFailed {
+                                       pending_events.lock().unwrap().push_back((events::Event::PaymentFailed {
                                                payment_id,
-                                               payment_hash: payment.get().payment_hash().expect("PendingOutboundPayments::RetriesExceeded always has a payment hash set"),
-                                       });
+                                               payment_hash: *payment_hash,
+                                               reason: *reason,
+                                       }, None));
                                        payment.remove();
                                }
+                       } else if let PendingOutboundPayment::AwaitingInvoice { .. } = payment.get() {
+                               pending_events.lock().unwrap().push_back((events::Event::InvoiceRequestFailed {
+                                       payment_id,
+                               }, None));
+                               payment.remove();
                        }
                }
        }
@@ -1335,19 +1679,32 @@ impl_writeable_tlv_based_enum_upgradable!(PendingOutboundPayment,
                (0, session_privs, required),
                (1, pending_fee_msat, option),
                (2, payment_hash, required),
-               (3, payment_params, option),
+               // Note that while we "default" payment_param's final CLTV expiry delta to 0 we should
+               // never see it - `payment_params` was added here after the field was added/required.
+               (3, payment_params, (option: ReadableArgs, 0)),
                (4, payment_secret, option),
                (5, keysend_preimage, option),
                (6, total_msat, required),
+               (7, payment_metadata, option),
                (8, pending_amt_msat, required),
+               (9, custom_tlvs, optional_vec),
                (10, starting_block_height, required),
                (not_written, retry_strategy, (static_value, None)),
                (not_written, attempts, (static_value, PaymentAttempts::new())),
        },
        (3, Abandoned) => {
                (0, session_privs, required),
+               (1, reason, option),
                (2, payment_hash, required),
        },
+       (5, AwaitingInvoice) => {
+               (0, timer_ticks_without_response, required),
+               (2, retry_strategy, required),
+       },
+       (7, InvoiceReceived) => {
+               (0, payment_hash, required),
+               (2, retry_strategy, required),
+       },
 );
 
 #[cfg(test)]
@@ -1355,16 +1712,45 @@ mod tests {
        use bitcoin::network::constants::Network;
        use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
 
+       use crate::events::{Event, PathFailure, PaymentFailureReason};
        use crate::ln::PaymentHash;
-       use crate::ln::channelmanager::PaymentId;
+       use crate::ln::channelmanager::{PaymentId, RecipientOnionFields};
+       use crate::ln::features::{ChannelFeatures, NodeFeatures};
        use crate::ln::msgs::{ErrorAction, LightningError};
-       use crate::ln::outbound_payment::{OutboundPayments, Retry, RetryableSendFailure};
+       use crate::ln::outbound_payment::{Bolt12PaymentError, INVOICE_REQUEST_TIMEOUT_TICKS, OutboundPayments, Retry, RetryableSendFailure};
+       use crate::offers::invoice::DEFAULT_RELATIVE_EXPIRY;
+       use crate::offers::offer::OfferBuilder;
+       use crate::offers::test_utils::*;
        use crate::routing::gossip::NetworkGraph;
-       use crate::routing::router::{InFlightHtlcs, PaymentParameters, Route, RouteParameters};
-       use crate::sync::{Arc, Mutex};
-       use crate::util::events::Event;
+       use crate::routing::router::{InFlightHtlcs, Path, PaymentParameters, Route, RouteHop, RouteParameters};
+       use crate::sync::{Arc, Mutex, RwLock};
+       use crate::util::errors::APIError;
        use crate::util::test_utils;
 
+       use alloc::collections::VecDeque;
+
+       #[test]
+       fn test_recipient_onion_fields_with_custom_tlvs() {
+               let onion_fields = RecipientOnionFields::spontaneous_empty();
+
+               let bad_type_range_tlvs = vec![
+                       (0, vec![42]),
+                       (1, vec![42; 32]),
+               ];
+               assert!(onion_fields.clone().with_custom_tlvs(bad_type_range_tlvs).is_err());
+
+               let keysend_tlv = vec![
+                       (5482373484, vec![42; 32]),
+               ];
+               assert!(onion_fields.clone().with_custom_tlvs(keysend_tlv).is_err());
+
+               let good_tlvs = vec![
+                       ((1 << 16) + 1, vec![42]),
+                       ((1 << 16) + 3, vec![42; 32]),
+               ];
+               assert!(onion_fields.with_custom_tlvs(good_tlvs).is_ok());
+       }
+
        #[test]
        #[cfg(feature = "std")]
        fn fails_paying_after_expiration() {
@@ -1376,7 +1762,7 @@ mod tests {
                let outbound_payments = OutboundPayments::new();
                let logger = test_utils::TestLogger::new();
                let network_graph = Arc::new(NetworkGraph::new(Network::Testnet, &logger));
-               let scorer = Mutex::new(test_utils::TestScorer::new());
+               let scorer = RwLock::new(test_utils::TestScorer::new());
                let router = test_utils::TestRouter::new(network_graph, &scorer);
                let secp_ctx = Secp256k1::new();
                let keys_manager = test_utils::TestKeysInterface::new(&[0; 32], Network::Testnet);
@@ -1386,28 +1772,27 @@ mod tests {
                                PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap()),
                                0
                        ).with_expiry_time(past_expiry_time);
-               let expired_route_params = RouteParameters {
-                       payment_params,
-                       final_value_msat: 0,
-                       final_cltv_expiry_delta: 0,
-               };
-               let pending_events = Mutex::new(Vec::new());
+               let expired_route_params = RouteParameters::from_payment_params_and_value(payment_params, 0);
+               let pending_events = Mutex::new(VecDeque::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(()));
+                       outbound_payments.add_new_pending_payment(PaymentHash([0; 32]), RecipientOnionFields::spontaneous_empty(),
+                               PaymentId([0; 32]), None, &Route { paths: vec![], route_params: None },
+                               Some(Retry::Attempts(1)), Some(expired_route_params.payment_params.clone()),
+                               &&keys_manager, 0).unwrap();
+                       outbound_payments.find_route_and_send_payment(
+                               PaymentHash([0; 32]), 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"); }
+                       if let Event::PaymentFailed { ref reason, .. } = events[0].0 {
+                               assert_eq!(reason.unwrap(), PaymentFailureReason::PaymentExpired);
+                       } else { panic!("Unexpected event"); }
                } else {
                        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,
-                               &pending_events, |_, _, _, _, _, _, _, _, _| Ok(())).unwrap_err();
+                               PaymentHash([0; 32]), RecipientOnionFields::spontaneous_empty(), PaymentId([0; 32]),
+                               Retry::Attempts(0), expired_route_params, &&router, vec![], || InFlightHtlcs::new(),
+                               &&keys_manager, &&keys_manager, 0, &&logger, &pending_events, |_| Ok(())).unwrap_err();
                        if let RetryableSendFailure::PaymentExpired = err { } else { panic!("Unexpected error"); }
                }
        }
@@ -1421,40 +1806,406 @@ mod tests {
                let outbound_payments = OutboundPayments::new();
                let logger = test_utils::TestLogger::new();
                let network_graph = Arc::new(NetworkGraph::new(Network::Testnet, &logger));
-               let scorer = Mutex::new(test_utils::TestScorer::new());
+               let scorer = RwLock::new(test_utils::TestScorer::new());
                let router = test_utils::TestRouter::new(network_graph, &scorer);
                let secp_ctx = Secp256k1::new();
                let keys_manager = test_utils::TestKeysInterface::new(&[0; 32], Network::Testnet);
 
                let payment_params = PaymentParameters::from_node_id(
                        PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap()), 0);
-               let route_params = RouteParameters {
-                       payment_params,
-                       final_value_msat: 0,
-                       final_cltv_expiry_delta: 0,
-               };
+               let route_params = RouteParameters::from_payment_params_and_value(payment_params, 0);
                router.expect_find_route(route_params.clone(),
                        Err(LightningError { err: String::new(), action: ErrorAction::IgnoreError }));
 
-               let pending_events = Mutex::new(Vec::new());
+               let pending_events = Mutex::new(VecDeque::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.retry_payment_internal(
-                               PaymentId([0; 32]), route_params, &&router, vec![], &|| InFlightHtlcs::new(),
-                               &&keys_manager, &&keys_manager, 0, &&logger, &pending_events,
-                               &|_, _, _, _, _, _, _, _, _| Ok(()));
+                       outbound_payments.add_new_pending_payment(PaymentHash([0; 32]), RecipientOnionFields::spontaneous_empty(),
+                               PaymentId([0; 32]), None, &Route { paths: vec![], route_params: None },
+                               Some(Retry::Attempts(1)), Some(route_params.payment_params.clone()),
+                               &&keys_manager, 0).unwrap();
+                       outbound_payments.find_route_and_send_payment(
+                               PaymentHash([0; 32]), 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"); }
+                       if let Event::PaymentFailed { .. } = events[0].0 { } else { panic!("Unexpected event"); }
                } else {
                        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,
-                               &pending_events, |_, _, _, _, _, _, _, _, _| Ok(())).unwrap_err();
+                               PaymentHash([0; 32]), RecipientOnionFields::spontaneous_empty(), PaymentId([0; 32]),
+                               Retry::Attempts(0), route_params, &&router, vec![], || InFlightHtlcs::new(),
+                               &&keys_manager, &&keys_manager, 0, &&logger, &pending_events, |_| Ok(())).unwrap_err();
                        if let RetryableSendFailure::RouteNotFound = err {
                        } else { panic!("Unexpected error"); }
                }
        }
+
+       #[test]
+       fn initial_send_payment_path_failed_evs() {
+               let outbound_payments = OutboundPayments::new();
+               let logger = test_utils::TestLogger::new();
+               let network_graph = Arc::new(NetworkGraph::new(Network::Testnet, &logger));
+               let scorer = RwLock::new(test_utils::TestScorer::new());
+               let router = test_utils::TestRouter::new(network_graph, &scorer);
+               let secp_ctx = Secp256k1::new();
+               let keys_manager = test_utils::TestKeysInterface::new(&[0; 32], Network::Testnet);
+
+               let sender_pk = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap());
+               let receiver_pk = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[43; 32]).unwrap());
+               let payment_params = PaymentParameters::from_node_id(sender_pk, 0);
+               let route_params = RouteParameters::from_payment_params_and_value(payment_params.clone(), 0);
+               let failed_scid = 42;
+               let route = Route {
+                       paths: vec![Path { hops: vec![RouteHop {
+                               pubkey: receiver_pk,
+                               node_features: NodeFeatures::empty(),
+                               short_channel_id: failed_scid,
+                               channel_features: ChannelFeatures::empty(),
+                               fee_msat: 0,
+                               cltv_expiry_delta: 0,
+                               maybe_announced_channel: true,
+                       }], blinded_tail: None }],
+                       route_params: Some(route_params.clone()),
+               };
+               router.expect_find_route(route_params.clone(), Ok(route.clone()));
+               let mut route_params_w_failed_scid = route_params.clone();
+               route_params_w_failed_scid.payment_params.previously_failed_channels.push(failed_scid);
+               router.expect_find_route(route_params_w_failed_scid, Ok(route.clone()));
+               router.expect_find_route(route_params.clone(), Ok(route.clone()));
+               router.expect_find_route(route_params.clone(), Ok(route.clone()));
+
+               // Ensure that a ChannelUnavailable error will result in blaming an scid in the
+               // PaymentPathFailed event.
+               let pending_events = Mutex::new(VecDeque::new());
+               outbound_payments.send_payment(
+                       PaymentHash([0; 32]), RecipientOnionFields::spontaneous_empty(), PaymentId([0; 32]),
+                       Retry::Attempts(0), route_params.clone(), &&router, vec![], || InFlightHtlcs::new(),
+                       &&keys_manager, &&keys_manager, 0, &&logger, &pending_events,
+                       |_| Err(APIError::ChannelUnavailable { err: "test".to_owned() })).unwrap();
+               let mut events = pending_events.lock().unwrap();
+               assert_eq!(events.len(), 2);
+               if let Event::PaymentPathFailed {
+                       short_channel_id,
+                       failure: PathFailure::InitialSend { err: APIError::ChannelUnavailable { .. }}, .. } = events[0].0
+               {
+                       assert_eq!(short_channel_id, Some(failed_scid));
+               } else { panic!("Unexpected event"); }
+               if let Event::PaymentFailed { .. } = events[1].0 { } else { panic!("Unexpected event"); }
+               events.clear();
+               core::mem::drop(events);
+
+               // Ensure that a MonitorUpdateInProgress "error" will not result in a PaymentPathFailed event.
+               outbound_payments.send_payment(
+                       PaymentHash([0; 32]), RecipientOnionFields::spontaneous_empty(), PaymentId([0; 32]),
+                       Retry::Attempts(0), route_params.clone(), &&router, vec![], || InFlightHtlcs::new(),
+                       &&keys_manager, &&keys_manager, 0, &&logger, &pending_events,
+                       |_| Err(APIError::MonitorUpdateInProgress)).unwrap();
+               assert_eq!(pending_events.lock().unwrap().len(), 0);
+
+               // Ensure that any other error will result in a PaymentPathFailed event but no blamed scid.
+               outbound_payments.send_payment(
+                       PaymentHash([0; 32]), RecipientOnionFields::spontaneous_empty(), PaymentId([1; 32]),
+                       Retry::Attempts(0), route_params.clone(), &&router, vec![], || InFlightHtlcs::new(),
+                       &&keys_manager, &&keys_manager, 0, &&logger, &pending_events,
+                       |_| Err(APIError::APIMisuseError { err: "test".to_owned() })).unwrap();
+               let events = pending_events.lock().unwrap();
+               assert_eq!(events.len(), 2);
+               if let Event::PaymentPathFailed {
+                       short_channel_id,
+                       failure: PathFailure::InitialSend { err: APIError::APIMisuseError { .. }}, .. } = events[0].0
+               {
+                       assert_eq!(short_channel_id, None);
+               } else { panic!("Unexpected event"); }
+               if let Event::PaymentFailed { .. } = events[1].0 { } else { panic!("Unexpected event"); }
+       }
+
+       #[test]
+       fn removes_stale_awaiting_invoice() {
+               let pending_events = Mutex::new(VecDeque::new());
+               let outbound_payments = OutboundPayments::new();
+               let payment_id = PaymentId([0; 32]);
+
+               assert!(!outbound_payments.has_pending_payments());
+               assert!(outbound_payments.add_new_awaiting_invoice(payment_id, Retry::Attempts(0)).is_ok());
+               assert!(outbound_payments.has_pending_payments());
+
+               for _ in 0..INVOICE_REQUEST_TIMEOUT_TICKS {
+                       outbound_payments.remove_stale_payments(&pending_events);
+                       assert!(outbound_payments.has_pending_payments());
+                       assert!(pending_events.lock().unwrap().is_empty());
+               }
+
+               outbound_payments.remove_stale_payments(&pending_events);
+               assert!(!outbound_payments.has_pending_payments());
+               assert!(!pending_events.lock().unwrap().is_empty());
+               assert_eq!(
+                       pending_events.lock().unwrap().pop_front(),
+                       Some((Event::InvoiceRequestFailed { payment_id }, None)),
+               );
+               assert!(pending_events.lock().unwrap().is_empty());
+
+               assert!(outbound_payments.add_new_awaiting_invoice(payment_id, Retry::Attempts(0)).is_ok());
+               assert!(outbound_payments.has_pending_payments());
+
+               assert!(outbound_payments.add_new_awaiting_invoice(payment_id, Retry::Attempts(0)).is_err());
+       }
+
+       #[test]
+       fn removes_abandoned_awaiting_invoice() {
+               let pending_events = Mutex::new(VecDeque::new());
+               let outbound_payments = OutboundPayments::new();
+               let payment_id = PaymentId([0; 32]);
+
+               assert!(!outbound_payments.has_pending_payments());
+               assert!(outbound_payments.add_new_awaiting_invoice(payment_id, Retry::Attempts(0)).is_ok());
+               assert!(outbound_payments.has_pending_payments());
+
+               outbound_payments.abandon_payment(
+                       payment_id, PaymentFailureReason::UserAbandoned, &pending_events
+               );
+               assert!(!outbound_payments.has_pending_payments());
+               assert!(!pending_events.lock().unwrap().is_empty());
+               assert_eq!(
+                       pending_events.lock().unwrap().pop_front(),
+                       Some((Event::InvoiceRequestFailed { payment_id }, None)),
+               );
+               assert!(pending_events.lock().unwrap().is_empty());
+       }
+
+       #[cfg(feature = "std")]
+       #[test]
+       fn fails_sending_payment_for_expired_bolt12_invoice() {
+               let logger = test_utils::TestLogger::new();
+               let network_graph = Arc::new(NetworkGraph::new(Network::Testnet, &logger));
+               let scorer = RwLock::new(test_utils::TestScorer::new());
+               let router = test_utils::TestRouter::new(network_graph, &scorer);
+               let keys_manager = test_utils::TestKeysInterface::new(&[0; 32], Network::Testnet);
+
+               let pending_events = Mutex::new(VecDeque::new());
+               let outbound_payments = OutboundPayments::new();
+               let payment_id = PaymentId([0; 32]);
+
+               assert!(outbound_payments.add_new_awaiting_invoice(payment_id, Retry::Attempts(0)).is_ok());
+               assert!(outbound_payments.has_pending_payments());
+
+               let created_at = now() - DEFAULT_RELATIVE_EXPIRY;
+               let invoice = OfferBuilder::new("foo".into(), recipient_pubkey())
+                       .amount_msats(1000)
+                       .build().unwrap()
+                       .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
+                       .build().unwrap()
+                       .sign(payer_sign).unwrap()
+                       .respond_with_no_std(payment_paths(), payment_hash(), created_at).unwrap()
+                       .build().unwrap()
+                       .sign(recipient_sign).unwrap();
+
+               assert_eq!(
+                       outbound_payments.send_payment_for_bolt12_invoice(
+                               &invoice, payment_id, &&router, vec![], || InFlightHtlcs::new(), &&keys_manager,
+                               &&keys_manager, 0, &&logger, &pending_events, |_| panic!()
+                       ),
+                       Ok(()),
+               );
+               assert!(!outbound_payments.has_pending_payments());
+
+               let payment_hash = invoice.payment_hash();
+               let reason = Some(PaymentFailureReason::PaymentExpired);
+
+               assert!(!pending_events.lock().unwrap().is_empty());
+               assert_eq!(
+                       pending_events.lock().unwrap().pop_front(),
+                       Some((Event::PaymentFailed { payment_id, payment_hash, reason }, None)),
+               );
+               assert!(pending_events.lock().unwrap().is_empty());
+       }
+
+       #[test]
+       fn fails_finding_route_for_bolt12_invoice() {
+               let logger = test_utils::TestLogger::new();
+               let network_graph = Arc::new(NetworkGraph::new(Network::Testnet, &logger));
+               let scorer = RwLock::new(test_utils::TestScorer::new());
+               let router = test_utils::TestRouter::new(network_graph, &scorer);
+               let keys_manager = test_utils::TestKeysInterface::new(&[0; 32], Network::Testnet);
+
+               let pending_events = Mutex::new(VecDeque::new());
+               let outbound_payments = OutboundPayments::new();
+               let payment_id = PaymentId([0; 32]);
+
+               assert!(outbound_payments.add_new_awaiting_invoice(payment_id, Retry::Attempts(0)).is_ok());
+               assert!(outbound_payments.has_pending_payments());
+
+               let invoice = OfferBuilder::new("foo".into(), recipient_pubkey())
+                       .amount_msats(1000)
+                       .build().unwrap()
+                       .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
+                       .build().unwrap()
+                       .sign(payer_sign).unwrap()
+                       .respond_with_no_std(payment_paths(), payment_hash(), now()).unwrap()
+                       .build().unwrap()
+                       .sign(recipient_sign).unwrap();
+
+               router.expect_find_route(
+                       RouteParameters {
+                               payment_params: PaymentParameters::from_bolt12_invoice(&invoice),
+                               final_value_msat: invoice.amount_msats(),
+                       },
+                       Err(LightningError { err: String::new(), action: ErrorAction::IgnoreError }),
+               );
+
+               assert_eq!(
+                       outbound_payments.send_payment_for_bolt12_invoice(
+                               &invoice, payment_id, &&router, vec![], || InFlightHtlcs::new(), &&keys_manager,
+                               &&keys_manager, 0, &&logger, &pending_events, |_| panic!()
+                       ),
+                       Ok(()),
+               );
+               assert!(!outbound_payments.has_pending_payments());
+
+               let payment_hash = invoice.payment_hash();
+               let reason = Some(PaymentFailureReason::RouteNotFound);
+
+               assert!(!pending_events.lock().unwrap().is_empty());
+               assert_eq!(
+                       pending_events.lock().unwrap().pop_front(),
+                       Some((Event::PaymentFailed { payment_id, payment_hash, reason }, None)),
+               );
+               assert!(pending_events.lock().unwrap().is_empty());
+       }
+
+       #[test]
+       fn fails_paying_for_bolt12_invoice() {
+               let logger = test_utils::TestLogger::new();
+               let network_graph = Arc::new(NetworkGraph::new(Network::Testnet, &logger));
+               let scorer = RwLock::new(test_utils::TestScorer::new());
+               let router = test_utils::TestRouter::new(network_graph, &scorer);
+               let keys_manager = test_utils::TestKeysInterface::new(&[0; 32], Network::Testnet);
+
+               let pending_events = Mutex::new(VecDeque::new());
+               let outbound_payments = OutboundPayments::new();
+               let payment_id = PaymentId([0; 32]);
+
+               assert!(outbound_payments.add_new_awaiting_invoice(payment_id, Retry::Attempts(0)).is_ok());
+               assert!(outbound_payments.has_pending_payments());
+
+               let invoice = OfferBuilder::new("foo".into(), recipient_pubkey())
+                       .amount_msats(1000)
+                       .build().unwrap()
+                       .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
+                       .build().unwrap()
+                       .sign(payer_sign).unwrap()
+                       .respond_with_no_std(payment_paths(), payment_hash(), now()).unwrap()
+                       .build().unwrap()
+                       .sign(recipient_sign).unwrap();
+
+               let route_params = RouteParameters {
+                       payment_params: PaymentParameters::from_bolt12_invoice(&invoice),
+                       final_value_msat: invoice.amount_msats(),
+               };
+               router.expect_find_route(
+                       route_params.clone(), Ok(Route { paths: vec![], route_params: Some(route_params) })
+               );
+
+               assert_eq!(
+                       outbound_payments.send_payment_for_bolt12_invoice(
+                               &invoice, payment_id, &&router, vec![], || InFlightHtlcs::new(), &&keys_manager,
+                               &&keys_manager, 0, &&logger, &pending_events, |_| panic!()
+                       ),
+                       Ok(()),
+               );
+               assert!(!outbound_payments.has_pending_payments());
+
+               let payment_hash = invoice.payment_hash();
+               let reason = Some(PaymentFailureReason::UnexpectedError);
+
+               assert!(!pending_events.lock().unwrap().is_empty());
+               assert_eq!(
+                       pending_events.lock().unwrap().pop_front(),
+                       Some((Event::PaymentFailed { payment_id, payment_hash, reason }, None)),
+               );
+               assert!(pending_events.lock().unwrap().is_empty());
+       }
+
+       #[test]
+       fn sends_payment_for_bolt12_invoice() {
+               let logger = test_utils::TestLogger::new();
+               let network_graph = Arc::new(NetworkGraph::new(Network::Testnet, &logger));
+               let scorer = RwLock::new(test_utils::TestScorer::new());
+               let router = test_utils::TestRouter::new(network_graph, &scorer);
+               let keys_manager = test_utils::TestKeysInterface::new(&[0; 32], Network::Testnet);
+
+               let pending_events = Mutex::new(VecDeque::new());
+               let outbound_payments = OutboundPayments::new();
+               let payment_id = PaymentId([0; 32]);
+
+               let invoice = OfferBuilder::new("foo".into(), recipient_pubkey())
+                       .amount_msats(1000)
+                       .build().unwrap()
+                       .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
+                       .build().unwrap()
+                       .sign(payer_sign).unwrap()
+                       .respond_with_no_std(payment_paths(), payment_hash(), now()).unwrap()
+                       .build().unwrap()
+                       .sign(recipient_sign).unwrap();
+
+               let route_params = RouteParameters {
+                       payment_params: PaymentParameters::from_bolt12_invoice(&invoice),
+                       final_value_msat: invoice.amount_msats(),
+               };
+               router.expect_find_route(
+                       route_params.clone(),
+                       Ok(Route {
+                               paths: vec![
+                                       Path {
+                                               hops: vec![
+                                                       RouteHop {
+                                                               pubkey: recipient_pubkey(),
+                                                               node_features: NodeFeatures::empty(),
+                                                               short_channel_id: 42,
+                                                               channel_features: ChannelFeatures::empty(),
+                                                               fee_msat: invoice.amount_msats(),
+                                                               cltv_expiry_delta: 0,
+                                                               maybe_announced_channel: true,
+                                                       }
+                                               ],
+                                               blinded_tail: None,
+                                       }
+                               ],
+                               route_params: Some(route_params),
+                       })
+               );
+
+               assert!(!outbound_payments.has_pending_payments());
+               assert_eq!(
+                       outbound_payments.send_payment_for_bolt12_invoice(
+                               &invoice, payment_id, &&router, vec![], || InFlightHtlcs::new(), &&keys_manager,
+                               &&keys_manager, 0, &&logger, &pending_events, |_| panic!()
+                       ),
+                       Err(Bolt12PaymentError::UnexpectedInvoice),
+               );
+               assert!(!outbound_payments.has_pending_payments());
+               assert!(pending_events.lock().unwrap().is_empty());
+
+               assert!(outbound_payments.add_new_awaiting_invoice(payment_id, Retry::Attempts(0)).is_ok());
+               assert!(outbound_payments.has_pending_payments());
+
+               assert_eq!(
+                       outbound_payments.send_payment_for_bolt12_invoice(
+                               &invoice, payment_id, &&router, vec![], || InFlightHtlcs::new(), &&keys_manager,
+                               &&keys_manager, 0, &&logger, &pending_events, |_| Ok(())
+                       ),
+                       Ok(()),
+               );
+               assert!(outbound_payments.has_pending_payments());
+               assert!(pending_events.lock().unwrap().is_empty());
+
+               assert_eq!(
+                       outbound_payments.send_payment_for_bolt12_invoice(
+                               &invoice, payment_id, &&router, vec![], || InFlightHtlcs::new(), &&keys_manager,
+                               &&keys_manager, 0, &&logger, &pending_events, |_| panic!()
+                       ),
+                       Err(Bolt12PaymentError::DuplicateInvoice),
+               );
+               assert!(outbound_payments.has_pending_payments());
+               assert!(pending_events.lock().unwrap().is_empty());
+       }
 }