Add PendingOutboundPayment::InvoiceReceived

When a BOLT 12 invoice has been received, a payment attempt is made and
any errors result in abandoning the PendingOutboundPayment. This results
in generating at PaymentFailed event, which has a PaymentHash. Thus,
when receiving an invoice, transition from AwaitingInvoice to a new
InvoiceReceived state, the latter of which contains a PaymentHash such
the abandon_payment helper can still be used.

Author: jkczyz

lightning/src/ln/channelmanager.rs

@@ -1697,6 +1697,13 @@ pub enum RecentPaymentDetails {
 		/// Identifier for the payment to ensure idempotency.
 		payment_id: PaymentId,
 	},
+	/// When a requested invoice has been received, but a payment has not yet been sent.
+	InvoiceReceived {
+		/// Identifier for the payment to ensure idempotency.
+		payment_id: PaymentId,
+		/// Hash of the payment that has not yet been sent.
+		payment_hash: PaymentHash,
+	},
 	/// When a payment is still being sent and awaiting successful delivery.
 	Pending {
 		/// Hash of the payment that is currently being sent but has yet to be fulfilled or
@@ -2432,6 +2439,11 @@ where
 				PendingOutboundPayment::AwaitingInvoice { .. } => {
 					Some(RecentPaymentDetails::AwaitingInvoice { payment_id: *payment_id })
 				},
+				PendingOutboundPayment::InvoiceReceived { payment_hash } => {
+					Some(RecentPaymentDetails::InvoiceReceived {
+						payment_id: *payment_id, payment_hash: *payment_hash
+					})
+				},
 				PendingOutboundPayment::Retryable { payment_hash, total_msat, .. } => {
 					Some(RecentPaymentDetails::Pending {
 						payment_hash: *payment_hash,
@@ -8358,6 +8370,7 @@ where
 					}
 				}
 				PendingOutboundPayment::AwaitingInvoice { .. } => {},
+				PendingOutboundPayment::InvoiceReceived { .. } => {},
 				PendingOutboundPayment::Fulfilled { .. } => {},
 				PendingOutboundPayment::Abandoned { .. } => {},
 			}

lightning/src/ln/outbound_payment.rs

@@ -41,6 +41,9 @@ pub(crate) enum PendingOutboundPayment {
 	AwaitingInvoice {
 		timer_ticks_without_response: u8,
 	},
+	InvoiceReceived {
+		payment_hash: PaymentHash,
+	},
 	Retryable {
 		retry_strategy: Option<Retry>,
 		attempts: PaymentAttempts,
@@ -140,6 +143,7 @@ impl PendingOutboundPayment {
 		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),
@@ -153,10 +157,8 @@ impl PendingOutboundPayment {
 				PendingOutboundPayment::Retryable { session_privs, .. } |
 				PendingOutboundPayment::Fulfilled { session_privs, .. } |
 				PendingOutboundPayment::Abandoned { session_privs, .. } => session_privs,
-			PendingOutboundPayment::AwaitingInvoice { .. } => {
-				debug_assert!(false);
-				return;
-			},
+			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 };
@@ -171,6 +173,12 @@ impl PendingOutboundPayment {
 				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)
+			};
 		}
 	}
 
@@ -184,6 +192,7 @@ impl PendingOutboundPayment {
 					session_privs.remove(session_priv)
 				},
 			PendingOutboundPayment::AwaitingInvoice { .. } => false,
+			PendingOutboundPayment::InvoiceReceived { .. } => false,
 		};
 		if remove_res {
 			if let PendingOutboundPayment::Retryable { ref mut pending_amt_msat, ref mut pending_fee_msat, .. } = self {
@@ -204,6 +213,7 @@ impl PendingOutboundPayment {
 					session_privs.insert(session_priv)
 				}
 			PendingOutboundPayment::AwaitingInvoice { .. } => false,
+			PendingOutboundPayment::InvoiceReceived { .. } => false,
 			PendingOutboundPayment::Fulfilled { .. } => false,
 			PendingOutboundPayment::Abandoned { .. } => false,
 		};
@@ -227,6 +237,7 @@ impl PendingOutboundPayment {
 					session_privs.len()
 				},
 			PendingOutboundPayment::AwaitingInvoice { .. } => 0,
+			PendingOutboundPayment::InvoiceReceived { .. } => 0,
 		}
 	}
 }
@@ -862,7 +873,9 @@ impl OutboundPayments {
 							log_error!(logger, "Unable to retry payments that were initially sent on LDK versions prior to 0.0.102");
 							return
 						},
-						PendingOutboundPayment::AwaitingInvoice { .. } => {
+						PendingOutboundPayment::AwaitingInvoice { .. } |
+							PendingOutboundPayment::InvoiceReceived { .. } =>
+						{
 							log_error!(logger, "Payment not yet sent");
 							return
 						},
@@ -1550,6 +1563,9 @@ impl_writeable_tlv_based_enum_upgradable!(PendingOutboundPayment,
 	(5, AwaitingInvoice) => {
 		(0, timer_ticks_without_response, required),
 	},
+	(7, InvoiceReceived) => {
+		(0, payment_hash, required),
+	},
 );
 
 #[cfg(test)]