Fix InflightHtlcs::process_path to process the whole Path

Author: valentinewallace

lightning/src/ln/channelmanager.rs

@@ -5698,7 +5698,7 @@ where
 			for chan in peer_state.channel_by_id.values() {
 				for (htlc_source, _) in chan.inflight_htlc_sources() {
 					if let HTLCSource::OutboundRoute { path, .. } = htlc_source {
-						inflight_htlcs.process_path(&path.hops, self.get_our_node_id()); // fixed in upcoming commit
+						inflight_htlcs.process_path(path, self.get_our_node_id());
 					}
 				}
 			}

lightning/src/routing/router.rs

@@ -170,22 +170,33 @@ impl InFlightHtlcs {
 	pub fn new() -> Self { InFlightHtlcs(HashMap::new()) }
 
 	/// Takes in a path with payer's node id and adds the path's details to `InFlightHtlcs`.
-	pub fn process_path(&mut self, path: &[RouteHop], payer_node_id: PublicKey) {
-		if path.is_empty() { return };
+	pub fn process_path(&mut self, path: &Path, payer_node_id: PublicKey) {
+		if path.len() == 0 { return };
+
+		let mut cumulative_msat = 0;
+		if let Some(tail) = &path.blinded_tail {
+			cumulative_msat += tail.final_value_msat + tail.fee_msat;
+			self.0
+				.entry((tail.intro_node_scid,
+						NodeId::from_pubkey(&path.hops.last().map_or(payer_node_id, |hop| hop.pubkey)) <
+						NodeId::from_pubkey(&tail.path.introduction_node_id)))
+				.and_modify(|used_liquidity_msat| *used_liquidity_msat += cumulative_msat)
+				.or_insert(cumulative_msat);
+		}
+
 		// total_inflight_map needs to be direction-sensitive when keeping track of the HTLC value
 		// that is held up. However, the `hops` array, which is a path returned by `find_route` in
 		// the router excludes the payer node. In the following lines, the payer's information is
 		// hardcoded with an inflight value of 0 so that we can correctly represent the first hop
 		// in our sliding window of two.
-		let reversed_hops_with_payer = path.iter().rev().skip(1)
+		let reversed_hops_with_payer = path.hops.iter().rev().skip(1)
 			.map(|hop| hop.pubkey)
 			.chain(core::iter::once(payer_node_id));
-		let mut cumulative_msat = 0;
 
 		// Taking the reversed vector from above, we zip it with just the reversed hops list to
 		// work "backwards" of the given path, since the last hop's `fee_msat` actually represents
 		// the total amount sent.
-		for (next_hop, prev_hop) in path.iter().rev().zip(reversed_hops_with_payer) {
+		for (next_hop, prev_hop) in path.hops.iter().rev().zip(reversed_hops_with_payer) {
 			cumulative_msat += next_hop.fee_msat;
 			self.0
 				.entry((next_hop.short_channel_id, NodeId::from_pubkey(&prev_hop) < NodeId::from_pubkey(&next_hop.pubkey)))