Add failing short channel id to PaymentPathFailed

This will be useful for scoring channels when a payment fails.

Author: jkczyz

lightning/src/ln/channelmanager.rs

@@ -2888,6 +2888,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 									network_update: None,
 									all_paths_failed: sessions.get().len() == 0,
 									path: path.clone(),
+									short_channel_id: None,
 									#[cfg(test)]
 									error_code: None,
 									#[cfg(test)]
@@ -2945,9 +2946,9 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 				match &onion_error {
 					&HTLCFailReason::LightningError { ref err } => {
 #[cfg(test)]
-						let (network_update, payment_retryable, onion_error_code, onion_error_data) = onion_utils::process_onion_failure(&self.secp_ctx, &self.logger, &source, err.data.clone());
+						let (network_update, short_channel_id, payment_retryable, onion_error_code, onion_error_data) = onion_utils::process_onion_failure(&self.secp_ctx, &self.logger, &source, err.data.clone());
 #[cfg(not(test))]
-						let (network_update, payment_retryable, _, _) = onion_utils::process_onion_failure(&self.secp_ctx, &self.logger, &source, err.data.clone());
+						let (network_update, short_channel_id, payment_retryable, _, _) = onion_utils::process_onion_failure(&self.secp_ctx, &self.logger, &source, err.data.clone());
 						// 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!
@@ -2958,6 +2959,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 								network_update,
 								all_paths_failed,
 								path: path.clone(),
+								short_channel_id,
 #[cfg(test)]
 								error_code: onion_error_code,
 #[cfg(test)]
@@ -2985,6 +2987,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 								network_update: None,
 								all_paths_failed,
 								path: path.clone(),
+								short_channel_id: Some(path.first().unwrap().short_channel_id),
 #[cfg(test)]
 								error_code: Some(*failure_code),
 #[cfg(test)]

lightning/src/ln/functional_tests.rs

@@ -6068,11 +6068,12 @@ fn test_fail_holding_cell_htlc_upon_free() {
 	let events = nodes[0].node.get_and_clear_pending_events();
 	assert_eq!(events.len(), 1);
 	match &events[0] {
-		&Event::PaymentPathFailed { ref payment_hash, ref rejected_by_dest, ref network_update, ref error_code, ref error_data, ref all_paths_failed, path: _ } => {
+		&Event::PaymentPathFailed { ref payment_hash, ref rejected_by_dest, ref network_update, ref all_paths_failed, path: _, ref short_channel_id, ref error_code, ref error_data } => {
 			assert_eq!(our_payment_hash.clone(), *payment_hash);
 			assert_eq!(*rejected_by_dest, false);
 			assert_eq!(*all_paths_failed, true);
 			assert_eq!(*network_update, None);
+			assert_eq!(*short_channel_id, None);
 			assert_eq!(*error_code, None);
 			assert_eq!(*error_data, None);
 		},
@@ -6155,11 +6156,12 @@ fn test_free_and_fail_holding_cell_htlcs() {
 	let events = nodes[0].node.get_and_clear_pending_events();
 	assert_eq!(events.len(), 1);
 	match &events[0] {
-		&Event::PaymentPathFailed { ref payment_hash, ref rejected_by_dest, ref network_update, ref error_code, ref error_data, ref all_paths_failed, path: _ } => {
+		&Event::PaymentPathFailed { ref payment_hash, ref rejected_by_dest, ref network_update, ref all_paths_failed, path: _, ref short_channel_id, ref error_code, ref error_data } => {
 			assert_eq!(payment_hash_2.clone(), *payment_hash);
 			assert_eq!(*rejected_by_dest, false);
 			assert_eq!(*all_paths_failed, true);
 			assert_eq!(*network_update, None);
+			assert_eq!(*short_channel_id, None);
 			assert_eq!(*error_code, None);
 			assert_eq!(*error_data, None);
 		},