Correct lowest_inbound_proportional_fee deduction in route finding

Found cause fuzzer was able to crash us if we don't

diff --git a/src/ln/router.rs b/src/ln/router.rs
index 22eba189d9e6bd4f3cbefaee4f2dae5c127db664..727a585879e9fcdb563636525c1c41ee8bf5d54f 100644 (file)
--- a/src/ln/router.rs
+++ b/src/ln/router.rs
@@ -303,6 +303,7 @@ impl RoutingMessageHandler for Router {
 struct RouteGraphNode {
        pubkey: PublicKey,
        lowest_fee_to_peer_through_node: u64,
+       lowest_fee_to_node: u64,
 }
 
 impl cmp::Ord for RouteGraphNode {
@@ -463,6 +464,7 @@ impl Router {
                                                let new_graph_node = RouteGraphNode {
                                                        pubkey: $directional_info.src_node_id,
                                                        lowest_fee_to_peer_through_node: total_fee,
+                                                       lowest_fee_to_node: $starting_fee_msat as u64 + new_fee,
                                                };
                                                if old_entry.0 > total_fee {
                                                        targets.push(new_graph_node);
@@ -527,7 +529,7 @@ impl Router {
                        }
                }
 
-               while let Some(RouteGraphNode { pubkey, lowest_fee_to_peer_through_node }) = targets.pop() {
+               while let Some(RouteGraphNode { pubkey, lowest_fee_to_node, .. }) = targets.pop() {
                        if pubkey == network.our_node_id {
                                let mut res = vec!(dist.remove(&network.our_node_id).unwrap().3);
                                while res.last().unwrap().pubkey != *target {
@@ -546,9 +548,7 @@ impl Router {
                        match network.nodes.get(&pubkey) {
                                None => {},
                                Some(node) => {
-                                       let mut fee = lowest_fee_to_peer_through_node - node.lowest_inbound_channel_fee_base_msat as u64;
-                                       fee -= node.lowest_inbound_channel_fee_proportional_millionths as u64 * (fee + final_value_msat) / 1000000;
-                                       add_entries_to_cheapest_to_target_node!(node, &pubkey, fee);
+                                       add_entries_to_cheapest_to_target_node!(node, &pubkey, lowest_fee_to_node);
                                },
                        }
                }