Fix tracking of collected value across pathfinding iterations

[rust-lightning] / lightning / src / routing / router.rs

diff --git a/lightning/src/routing/router.rs b/lightning/src/routing/router.rs
index a97e1b6ffa45db704b89505cfce7d6c58cc1f16b..88757e867c5255d45d017f38563e61afa704aa55 100644 (file)
--- a/lightning/src/routing/router.rs
+++ b/lightning/src/routing/router.rs
@@ -1476,7 +1476,7 @@ where L::Target: Logger {
                // Both these cases (and other cases except reaching recommended_value_msat) mean that
                // paths_collection will be stopped because found_new_path==false.
                // This is not necessarily a routing failure.
-               'path_construction: while let Some(RouteGraphNode { node_id, lowest_fee_to_node, total_cltv_delta, value_contribution_msat, path_htlc_minimum_msat, path_penalty_msat, path_length_to_node, .. }) = targets.pop() {
+               'path_construction: while let Some(RouteGraphNode { node_id, lowest_fee_to_node, total_cltv_delta, mut value_contribution_msat, path_htlc_minimum_msat, path_penalty_msat, path_length_to_node, .. }) = targets.pop() {
 
                        // Since we're going payee-to-payer, hitting our node as a target means we should stop
                        // traversing the graph and arrange the path out of what we found.
@@ -1542,7 +1542,9 @@ where L::Target: Logger {
                                // on some channels we already passed (assuming dest->source direction). Here, we
                                // recompute the fees again, so that if that's the case, we match the currently
                                // underpaid htlc_minimum_msat with fees.
-                               payment_path.update_value_and_recompute_fees(cmp::min(value_contribution_msat, final_value_msat));
+                               debug_assert_eq!(payment_path.get_value_msat(), value_contribution_msat);
+                               value_contribution_msat = cmp::min(value_contribution_msat, final_value_msat);
+                               payment_path.update_value_and_recompute_fees(value_contribution_msat);
 
                                // Since a path allows to transfer as much value as
                                // the smallest channel it has ("bottleneck"), we should recompute