Store previously failed blinded paths on outbound payment failure.

Useful so we don't retry over these paths.

Author: valentinewallace

lightning/src/ln/outbound_payment.rs

@@ -19,7 +19,7 @@ use crate::ln::{PaymentHash, PaymentPreimage, PaymentSecret};
 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::routing::router::{BlindedTail, InFlightHtlcs, Path, PaymentParameters, Route, RouteParameters, Router};
 use crate::util::errors::APIError;
 use crate::util::logger::Logger;
 use crate::util::time::Time;
@@ -129,6 +129,11 @@ impl PendingOutboundPayment {
 			params.previously_failed_channels.push(scid);
 		}
 	}
+	pub fn insert_previously_failed_blinded_path(&mut self, blinded_tail: &BlindedTail) {
+		if let PendingOutboundPayment::Retryable { payment_params: Some(params), .. } = self {
+			params.insert_previously_failed_blinded_path(blinded_tail);
+		}
+	}
 	fn is_awaiting_invoice(&self) -> bool {
 		match self {
 			PendingOutboundPayment::AwaitingInvoice { .. } => true,
@@ -1648,6 +1653,12 @@ impl OutboundPayments {
 				// next-hop is needlessly blaming us!
 				payment.get_mut().insert_previously_failed_scid(scid);
 			}
+			if failed_within_blinded_path {
+				debug_assert!(short_channel_id.is_none());
+				if let Some(bt) = &path.blinded_tail {
+					payment.get_mut().insert_previously_failed_blinded_path(&bt);
+				} else { debug_assert!(false); }
+			}
 
 			if payment_is_probe || !is_retryable_now || payment_failed_permanently {
 				let reason = if payment_failed_permanently {

lightning/src/routing/router.rs

@@ -914,6 +914,19 @@ impl PaymentParameters {
 	pub fn with_max_channel_saturation_power_of_half(self, max_channel_saturation_power_of_half: u8) -> Self {
 		Self { max_channel_saturation_power_of_half, ..self }
 	}
+
+	pub(crate) fn insert_previously_failed_blinded_path(&mut self, failed_blinded_tail: &BlindedTail) {
+		let mut found_blinded_tail = false;
+		for (idx, (_, path)) in self.payee.blinded_route_hints().iter().enumerate() {
+			if failed_blinded_tail.hops == path.blinded_hops &&
+				failed_blinded_tail.blinding_point == path.blinding_point
+			{
+				self.previously_failed_blinded_path_idxs.push(idx as u64);
+				found_blinded_tail = true;
+			}
+		}
+		debug_assert!(found_blinded_tail);
+	}
 }
 
 /// The recipient of a payment, differing based on whether they've hidden their identity with route