Add fees value for recent payments

Introduce fields `pending_fee_msat` for `RecentPaymentDetails::Pending`
and `fee_paid_msat` for `RecentPaymentDetails::Fulfilled`.

Author: randomlogin

lightning/src/ln/channelmanager.rs

@@ -3291,9 +3291,13 @@ pub enum RecentPaymentDetails {
 		/// Hash of the payment that is currently being sent but has yet to be fulfilled or
 		/// abandoned.
 		payment_hash: PaymentHash,
-		/// Total amount (in msat, excluding fees) across all paths for this payment,
+		/// Total amount (excluding fees) across all paths for this payment,
 		/// not just the amount currently inflight.
 		total_msat: u64,
+		/// Total routing fees of the HTLCs currently in-flight for this payment.
+		///
+		/// `None` for payments serialized by LDK versions prior to 0.0.103.
+		pending_fee_msat: Option<u64>,
 		/// Whether this payment is a liquidity probe.
 		is_probe: bool,
 	},
@@ -3310,6 +3314,13 @@ pub enum RecentPaymentDetails {
 		/// Hash of the payment that was claimed. `None` for serializations of [`ChannelManager`]
 		/// made before LDK version 0.0.104.
 		payment_hash: Option<PaymentHash>,
+		/// Total routing fees paid for this payment, as also reported via the `fee_paid_msat`
+		/// field of [`Event::PaymentSent`].
+		///
+		/// `None` for payments serialized by LDK versions prior to 0.3.0.
+		///
+		/// [`Event::PaymentSent`]: events::Event::PaymentSent
+		fee_paid_msat: Option<u64>,
 	},
 	/// After a payment's retries are exhausted per the provided [`Retry`], or it is explicitly
 	/// abandoned via [`ChannelManager::abandon_payment`], it is marked as abandoned until all
@@ -4118,12 +4129,13 @@ impl<
 				PendingOutboundPayment::StaticInvoiceReceived { .. } => {
 					Some(RecentPaymentDetails::AwaitingInvoice { payment_id: *payment_id })
 				},
-				PendingOutboundPayment::Retryable { payment_hash, total_msat, .. } => {
+				PendingOutboundPayment::Retryable { payment_hash, total_msat, pending_fee_msat, .. } => {
 					let is_probe = outbound_payment::payment_is_probe(payment_hash, payment_id, self.probing_cookie_secret);
 					Some(RecentPaymentDetails::Pending {
 						payment_id: *payment_id,
 						payment_hash: *payment_hash,
 						total_msat: *total_msat,
+						pending_fee_msat: *pending_fee_msat,
 						is_probe,
 					})
 				},
@@ -4135,8 +4147,12 @@ impl<
 						is_probe,
 					})
 				},
-				PendingOutboundPayment::Fulfilled { payment_hash, .. } => {
-					Some(RecentPaymentDetails::Fulfilled { payment_id: *payment_id, payment_hash: *payment_hash })
+				PendingOutboundPayment::Fulfilled { payment_hash, fee_paid_msat, .. } => {
+					Some(RecentPaymentDetails::Fulfilled {
+						payment_id: *payment_id,
+						payment_hash: *payment_hash,
+						fee_paid_msat: *fee_paid_msat,
+					})
 				},
 				PendingOutboundPayment::Legacy { .. } => None
 			})

lightning/src/ln/outbound_payment.rs

@@ -152,6 +152,8 @@ pub(crate) enum PendingOutboundPayment {
 		timer_ticks_without_htlcs: u8,
 		/// The total payment amount across all paths, used to be able to issue `PaymentSent`.
 		total_msat: Option<u64>,
+		/// Total routing fees paid, as reported in `PaymentSent::fee_paid_msat`.
+		fee_paid_msat: Option<u64>,
 	},
 	/// When we've decided to give up retrying a payment, we mark it as abandoned so we can eventually
 	/// generate a `PaymentFailed` event when all HTLCs have irrevocably failed.
@@ -256,6 +258,7 @@ impl PendingOutboundPayment {
 		match self {
 			PendingOutboundPayment::Retryable { pending_fee_msat, .. } => pending_fee_msat.clone(),
 			PendingOutboundPayment::Abandoned { pending_fee_msat, .. } => pending_fee_msat.clone(),
+			PendingOutboundPayment::Fulfilled { fee_paid_msat, .. } => fee_paid_msat.clone(),
 			_ => None,
 		}
 	}
@@ -298,7 +301,8 @@ impl PendingOutboundPayment {
 		});
 		let payment_hash = self.payment_hash();
 		let total_msat = self.total_msat();
-		*self = PendingOutboundPayment::Fulfilled { session_privs, payment_hash, timer_ticks_without_htlcs: 0, total_msat };
+		let fee_paid_msat = self.get_pending_fee_msat();
+		*self = PendingOutboundPayment::Fulfilled { session_privs, payment_hash, timer_ticks_without_htlcs: 0, total_msat, fee_paid_msat };
 	}
 
 	#[rustfmt::skip]
@@ -2743,6 +2747,7 @@ impl_writeable_tlv_based_enum_upgradable!(PendingOutboundPayment,
 		(1, payment_hash, option),
 		(3, timer_ticks_without_htlcs, (default_value, 0)),
 		(5, total_msat, option),
+		(7, fee_paid_msat, option),
 	},
 	(2, Retryable) => {
 		(0, session_privs, required),

lightning/src/ln/payment_tests.rs

@@ -2343,7 +2343,11 @@ fn test_trivial_inflight_htlc_tracking() {
 	}
 	let pending_payments = nodes[0].node.list_recent_payments();
 	assert_eq!(pending_payments.len(), 1);
-	let details = RecentPaymentDetails::Fulfilled { payment_hash: Some(payment_hash), payment_id };
+	let details = RecentPaymentDetails::Fulfilled {
+		payment_hash: Some(payment_hash),
+		payment_id,
+		fee_paid_msat: Some(1000),
+	};
 	assert_eq!(pending_payments[0], details);
 
 	// Remove fulfilled payment
@@ -2389,6 +2393,7 @@ fn test_trivial_inflight_htlc_tracking() {
 		payment_id,
 		payment_hash,
 		total_msat: 500000,
+		pending_fee_msat: Some(1000),
 		is_probe: false,
 	};
 	assert_eq!(pending_payments[0], details);