f - Add clarifying comments

Author: jkczyz

lightning/src/ln/onion_utils.rs

@@ -355,6 +355,8 @@ pub(super) fn process_onion_failure<T: secp256k1::Signing, L: Deref>(secp_ctx: &
 			chacha.process(&packet_decrypted, &mut decryption_tmp[..]);
 			packet_decrypted = decryption_tmp;
 
+			// The failing hop is either the channel leading to the recipient or the channel
+			// identified by the current hop.
 			is_from_final_node = route_hop_idx + 1 == path.len();
 			let failing_route_hop = if is_from_final_node { route_hop } else { &path[route_hop_idx + 1] };
 
@@ -430,6 +432,8 @@ pub(super) fn process_onion_failure<T: secp256k1::Signing, L: Deref>(secp_ctx: &
 												is_permanent: true,
 											});
 										} else {
+											// Make sure the ChannelUpdate contains the expected
+											// short channel id.
 											if failing_route_hop.short_channel_id == chan_update.contents.short_channel_id {
 												short_channel_id = Some(failing_route_hop.short_channel_id);
 											}