Merge pull request #1057 from TheBlueMatt/2021-08-invoice-fails
[rust-lightning] / lightning / src / routing / router.rs
index ea55ce1a9d004940dae4441c85b0a550bcf4aed7..5030f6aaacbf9569a0ff5e2d26a20a31104c0c9b 100644 (file)
@@ -375,10 +375,11 @@ pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, paye
                return Err(LightningError{err: "Cannot send a payment of 0 msat".to_owned(), action: ErrorAction::IgnoreError});
        }
 
-       let last_hops = last_hops.iter().filter_map(|hops| hops.0.last()).collect::<Vec<_>>();
-       for last_hop in last_hops.iter() {
-               if last_hop.src_node_id == *payee {
-                       return Err(LightningError{err: "Last hop cannot have a payee as a source.".to_owned(), action: ErrorAction::IgnoreError});
+       for route in last_hops.iter() {
+               for hop in &route.0 {
+                       if hop.src_node_id == *payee {
+                               return Err(LightningError{err: "Last hop cannot have a payee as a source.".to_owned(), action: ErrorAction::IgnoreError});
+                       }
                }
        }
 
@@ -876,39 +877,89 @@ pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, paye
                // If a caller provided us with last hops, add them to routing targets. Since this happens
                // earlier than general path finding, they will be somewhat prioritized, although currently
                // it matters only if the fees are exactly the same.
-               for hop in last_hops.iter() {
+               for route in last_hops.iter().filter(|route| !route.0.is_empty()) {
+                       let first_hop_in_route = &(route.0)[0];
                        let have_hop_src_in_graph =
-                               // Only add the last hop to our candidate set if either we have a direct channel or
-                               // they are in the regular network graph.
-                               first_hop_targets.get(&hop.src_node_id).is_some() ||
-                               network.get_nodes().get(&hop.src_node_id).is_some();
+                               // Only add the hops in this route to our candidate set if either
+                               // we have a direct channel to the first hop or the first hop is
+                               // in the regular network graph.
+                               first_hop_targets.get(&first_hop_in_route.src_node_id).is_some() ||
+                               network.get_nodes().get(&first_hop_in_route.src_node_id).is_some();
                        if have_hop_src_in_graph {
-                               // BOLT 11 doesn't allow inclusion of features for the last hop hints, which
-                               // really sucks, cause we're gonna need that eventually.
-                               let last_hop_htlc_minimum_msat: u64 = match hop.htlc_minimum_msat {
-                                       Some(htlc_minimum_msat) => htlc_minimum_msat,
-                                       None => 0
-                               };
-                               let directional_info = DummyDirectionalChannelInfo {
-                                       cltv_expiry_delta: hop.cltv_expiry_delta as u32,
-                                       htlc_minimum_msat: last_hop_htlc_minimum_msat,
-                                       htlc_maximum_msat: hop.htlc_maximum_msat,
-                                       fees: hop.fees,
-                               };
-                               // We assume that the recipient only included route hints for routes which had
-                               // sufficient value to route `final_value_msat`. Note that in the case of "0-value"
-                               // invoices where the invoice does not specify value this may not be the case, but
-                               // better to include the hints than not.
-                               if add_entry!(hop.short_channel_id, hop.src_node_id, payee, directional_info, Some((final_value_msat + 999) / 1000), &empty_channel_features, 0, path_value_msat, 0) {
-                                       // If this hop connects to a node with which we have a direct channel,
-                                       // ignore the network graph and, if the last hop was added, add our
-                                       // direct channel to the candidate set.
-                                       //
-                                       // Note that we *must* check if the last hop was added as `add_entry`
-                                       // always assumes that the third argument is a node to which we have a
-                                       // path.
-                                       if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat, _)) = first_hop_targets.get(&hop.src_node_id) {
-                                               add_entry!(first_hop, *our_node_id , hop.src_node_id, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, 0, path_value_msat, 0);
+                               // We start building the path from reverse, i.e., from payee
+                               // to the first RouteHintHop in the path.
+                               let hop_iter = route.0.iter().rev();
+                               let prev_hop_iter = core::iter::once(payee).chain(
+                                       route.0.iter().skip(1).rev().map(|hop| &hop.src_node_id));
+                               let mut hop_used = true;
+                               let mut aggregate_next_hops_fee_msat: u64 = 0;
+                               let mut aggregate_next_hops_path_htlc_minimum_msat: u64 = 0;
+
+                               for (idx, (hop, prev_hop_id)) in hop_iter.zip(prev_hop_iter).enumerate() {
+                                       // BOLT 11 doesn't allow inclusion of features for the last hop hints, which
+                                       // really sucks, cause we're gonna need that eventually.
+                                       let hop_htlc_minimum_msat: u64 = hop.htlc_minimum_msat.unwrap_or(0);
+
+                                       let directional_info = DummyDirectionalChannelInfo {
+                                               cltv_expiry_delta: hop.cltv_expiry_delta as u32,
+                                               htlc_minimum_msat: hop_htlc_minimum_msat,
+                                               htlc_maximum_msat: hop.htlc_maximum_msat,
+                                               fees: hop.fees,
+                                       };
+
+                                       let reqd_channel_cap = if let Some (val) = final_value_msat.checked_add(match idx {
+                                               0 => 999,
+                                               _ => aggregate_next_hops_fee_msat.checked_add(999).unwrap_or(u64::max_value())
+                                       }) { Some( val / 1000 ) } else { break; }; // converting from msat or breaking if max ~ infinity
+
+
+                                       // We assume that the recipient only included route hints for routes which had
+                                       // sufficient value to route `final_value_msat`. Note that in the case of "0-value"
+                                       // invoices where the invoice does not specify value this may not be the case, but
+                                       // better to include the hints than not.
+                                       if !add_entry!(hop.short_channel_id, hop.src_node_id, prev_hop_id, directional_info, reqd_channel_cap, &empty_channel_features, aggregate_next_hops_fee_msat, path_value_msat, aggregate_next_hops_path_htlc_minimum_msat) {
+                                               // If this hop was not used then there is no use checking the preceding hops
+                                               // in the RouteHint. We can break by just searching for a direct channel between
+                                               // last checked hop and first_hop_targets
+                                               hop_used = false;
+                                       }
+
+                                       // Searching for a direct channel between last checked hop and first_hop_targets
+                                       if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat, _)) = first_hop_targets.get(&prev_hop_id) {
+                                               add_entry!(first_hop, *our_node_id , prev_hop_id, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, aggregate_next_hops_fee_msat, path_value_msat, aggregate_next_hops_path_htlc_minimum_msat);
+                                       }
+
+                                       if !hop_used {
+                                               break;
+                                       }
+
+                                       // In the next values of the iterator, the aggregate fees already reflects
+                                       // the sum of value sent from payer (final_value_msat) and routing fees
+                                       // for the last node in the RouteHint. We need to just add the fees to
+                                       // route through the current node so that the preceeding node (next iteration)
+                                       // can use it.
+                                       let hops_fee = compute_fees(aggregate_next_hops_fee_msat + final_value_msat, hop.fees)
+                                               .map_or(None, |inc| inc.checked_add(aggregate_next_hops_fee_msat));
+                                       aggregate_next_hops_fee_msat = if let Some(val) = hops_fee { val } else { break; };
+
+                                       let hop_htlc_minimum_msat_inc = if let Some(val) = compute_fees(aggregate_next_hops_path_htlc_minimum_msat, hop.fees) { val } else { break; };
+                                       let hops_path_htlc_minimum = aggregate_next_hops_path_htlc_minimum_msat
+                                               .checked_add(hop_htlc_minimum_msat_inc);
+                                       aggregate_next_hops_path_htlc_minimum_msat = if let Some(val) = hops_path_htlc_minimum { cmp::max(hop_htlc_minimum_msat, val) } else { break; };
+
+                                       if idx == route.0.len() - 1 {
+                                               // The last hop in this iterator is the first hop in
+                                               // overall RouteHint.
+                                               // If this hop connects to a node with which we have a direct channel,
+                                               // ignore the network graph and, if the last hop was added, add our
+                                               // direct channel to the candidate set.
+                                               //
+                                               // Note that we *must* check if the last hop was added as `add_entry`
+                                               // always assumes that the third argument is a node to which we have a
+                                               // path.
+                                               if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat, _)) = first_hop_targets.get(&hop.src_node_id) {
+                                                       add_entry!(first_hop, *our_node_id , hop.src_node_id, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, aggregate_next_hops_fee_msat, path_value_msat, aggregate_next_hops_path_htlc_minimum_msat);
+                                               }
                                        }
                                }
                        }
@@ -1343,7 +1394,7 @@ mod tests {
                let logger = Arc::new(test_utils::TestLogger::new());
                let chain_monitor = Arc::new(test_utils::TestChainSource::new(Network::Testnet));
                let net_graph_msg_handler = NetGraphMsgHandler::new(genesis_block(Network::Testnet).header.block_hash(), None, Arc::clone(&logger));
-               // Build network from our_id to node7:
+               // Build network from our_id to node6:
                //
                //        -1(1)2-  node0  -1(3)2-
                //       /                       \
@@ -1379,6 +1430,8 @@ mod tests {
                //      \                      /
                //       -1(7)2- node5 -1(10)2-
                //
+               // Channels 5, 8, 9 and 10 are private channels.
+               //
                // chan5  1-to-2: enabled, 100 msat fee
                // chan5  2-to-1: enabled, 0 fee
                //
@@ -2105,7 +2158,51 @@ mod tests {
                        cltv_expiry_delta: (8 << 8) | 1,
                        htlc_minimum_msat: None,
                        htlc_maximum_msat: None,
+               }
+               ]), RouteHint(vec![RouteHintHop {
+                       src_node_id: nodes[4].clone(),
+                       short_channel_id: 9,
+                       fees: RoutingFees {
+                               base_msat: 1001,
+                               proportional_millionths: 0,
+                       },
+                       cltv_expiry_delta: (9 << 8) | 1,
+                       htlc_minimum_msat: None,
+                       htlc_maximum_msat: None,
                }]), RouteHint(vec![RouteHintHop {
+                       src_node_id: nodes[5].clone(),
+                       short_channel_id: 10,
+                       fees: zero_fees,
+                       cltv_expiry_delta: (10 << 8) | 1,
+                       htlc_minimum_msat: None,
+                       htlc_maximum_msat: None,
+               }])]
+       }
+
+       fn last_hops_multi_private_channels(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
+               let zero_fees = RoutingFees {
+                       base_msat: 0,
+                       proportional_millionths: 0,
+               };
+               vec![RouteHint(vec![RouteHintHop {
+                       src_node_id: nodes[2].clone(),
+                       short_channel_id: 5,
+                       fees: RoutingFees {
+                               base_msat: 100,
+                               proportional_millionths: 0,
+                       },
+                       cltv_expiry_delta: (5 << 8) | 1,
+                       htlc_minimum_msat: None,
+                       htlc_maximum_msat: None,
+               }, RouteHintHop {
+                       src_node_id: nodes[3].clone(),
+                       short_channel_id: 8,
+                       fees: zero_fees,
+                       cltv_expiry_delta: (8 << 8) | 1,
+                       htlc_minimum_msat: None,
+                       htlc_maximum_msat: None,
+               }
+               ]), RouteHint(vec![RouteHintHop {
                        src_node_id: nodes[4].clone(),
                        short_channel_id: 9,
                        fees: RoutingFees {
@@ -2126,11 +2223,13 @@ mod tests {
        }
 
        #[test]
-       fn last_hops_test() {
+       fn partial_route_hint_test() {
                let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
                let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
 
                // Simple test across 2, 3, 5, and 4 via a last_hop channel
+               // Tests the behaviour when the RouteHint contains a suboptimal hop.
+               // RouteHint may be partially used by the algo to build the best path.
 
                // First check that last hop can't have its source as the payee.
                let invalid_last_hop = RouteHint(vec![RouteHintHop {
@@ -2145,7 +2244,7 @@ mod tests {
                        htlc_maximum_msat: None,
                }]);
 
-               let mut invalid_last_hops = last_hops(&nodes);
+               let mut invalid_last_hops = last_hops_multi_private_channels(&nodes);
                invalid_last_hops.push(invalid_last_hop);
                {
                        if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &invalid_last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)) {
@@ -2153,7 +2252,79 @@ mod tests {
                        } else { panic!(); }
                }
 
-               let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &last_hops(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
+               let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &last_hops_multi_private_channels(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
+               assert_eq!(route.paths[0].len(), 5);
+
+               assert_eq!(route.paths[0][0].pubkey, nodes[1]);
+               assert_eq!(route.paths[0][0].short_channel_id, 2);
+               assert_eq!(route.paths[0][0].fee_msat, 100);
+               assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
+               assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
+               assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
+
+               assert_eq!(route.paths[0][1].pubkey, nodes[2]);
+               assert_eq!(route.paths[0][1].short_channel_id, 4);
+               assert_eq!(route.paths[0][1].fee_msat, 0);
+               assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
+               assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
+               assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
+
+               assert_eq!(route.paths[0][2].pubkey, nodes[4]);
+               assert_eq!(route.paths[0][2].short_channel_id, 6);
+               assert_eq!(route.paths[0][2].fee_msat, 0);
+               assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
+               assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
+               assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
+
+               assert_eq!(route.paths[0][3].pubkey, nodes[3]);
+               assert_eq!(route.paths[0][3].short_channel_id, 11);
+               assert_eq!(route.paths[0][3].fee_msat, 0);
+               assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
+               // If we have a peer in the node map, we'll use their features here since we don't have
+               // a way of figuring out their features from the invoice:
+               assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
+               assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
+
+               assert_eq!(route.paths[0][4].pubkey, nodes[6]);
+               assert_eq!(route.paths[0][4].short_channel_id, 8);
+               assert_eq!(route.paths[0][4].fee_msat, 100);
+               assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
+               assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
+               assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
+       }
+
+       fn empty_last_hop(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
+               let zero_fees = RoutingFees {
+                       base_msat: 0,
+                       proportional_millionths: 0,
+               };
+               vec![RouteHint(vec![RouteHintHop {
+                       src_node_id: nodes[3].clone(),
+                       short_channel_id: 8,
+                       fees: zero_fees,
+                       cltv_expiry_delta: (8 << 8) | 1,
+                       htlc_minimum_msat: None,
+                       htlc_maximum_msat: None,
+               }]), RouteHint(vec![
+
+               ]), RouteHint(vec![RouteHintHop {
+                       src_node_id: nodes[5].clone(),
+                       short_channel_id: 10,
+                       fees: zero_fees,
+                       cltv_expiry_delta: (10 << 8) | 1,
+                       htlc_minimum_msat: None,
+                       htlc_maximum_msat: None,
+               }])]
+       }
+
+       #[test]
+       fn ignores_empty_last_hops_test() {
+               let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
+               let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
+
+               // Test handling of an empty RouteHint passed in Invoice.
+
+               let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &empty_last_hop(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
                assert_eq!(route.paths[0].len(), 5);
 
                assert_eq!(route.paths[0][0].pubkey, nodes[1]);
@@ -2194,6 +2365,190 @@ mod tests {
                assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
        }
 
+       fn multi_hint_last_hops(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
+               let zero_fees = RoutingFees {
+                       base_msat: 0,
+                       proportional_millionths: 0,
+               };
+               vec![RouteHint(vec![RouteHintHop {
+                       src_node_id: nodes[2].clone(),
+                       short_channel_id: 5,
+                       fees: RoutingFees {
+                               base_msat: 100,
+                               proportional_millionths: 0,
+                       },
+                       cltv_expiry_delta: (5 << 8) | 1,
+                       htlc_minimum_msat: None,
+                       htlc_maximum_msat: None,
+               }, RouteHintHop {
+                       src_node_id: nodes[3].clone(),
+                       short_channel_id: 8,
+                       fees: zero_fees,
+                       cltv_expiry_delta: (8 << 8) | 1,
+                       htlc_minimum_msat: None,
+                       htlc_maximum_msat: None,
+               }]), RouteHint(vec![RouteHintHop {
+                       src_node_id: nodes[5].clone(),
+                       short_channel_id: 10,
+                       fees: zero_fees,
+                       cltv_expiry_delta: (10 << 8) | 1,
+                       htlc_minimum_msat: None,
+                       htlc_maximum_msat: None,
+               }])]
+       }
+
+       #[test]
+       fn multi_hint_last_hops_test() {
+               let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
+               let (_, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
+               // Test through channels 2, 3, 5, 8.
+               // Test shows that multiple hop hints are considered.
+
+               // Disabling channels 6 & 7 by flags=2
+               update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
+                       chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+                       short_channel_id: 6,
+                       timestamp: 2,
+                       flags: 2, // to disable
+                       cltv_expiry_delta: 0,
+                       htlc_minimum_msat: 0,
+                       htlc_maximum_msat: OptionalField::Absent,
+                       fee_base_msat: 0,
+                       fee_proportional_millionths: 0,
+                       excess_data: Vec::new()
+               });
+               update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
+                       chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+                       short_channel_id: 7,
+                       timestamp: 2,
+                       flags: 2, // to disable
+                       cltv_expiry_delta: 0,
+                       htlc_minimum_msat: 0,
+                       htlc_maximum_msat: OptionalField::Absent,
+                       fee_base_msat: 0,
+                       fee_proportional_millionths: 0,
+                       excess_data: Vec::new()
+               });
+
+               let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &multi_hint_last_hops(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
+               assert_eq!(route.paths[0].len(), 4);
+
+               assert_eq!(route.paths[0][0].pubkey, nodes[1]);
+               assert_eq!(route.paths[0][0].short_channel_id, 2);
+               assert_eq!(route.paths[0][0].fee_msat, 200);
+               assert_eq!(route.paths[0][0].cltv_expiry_delta, 1025);
+               assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
+               assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
+
+               assert_eq!(route.paths[0][1].pubkey, nodes[2]);
+               assert_eq!(route.paths[0][1].short_channel_id, 4);
+               assert_eq!(route.paths[0][1].fee_msat, 100);
+               assert_eq!(route.paths[0][1].cltv_expiry_delta, 1281);
+               assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
+               assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
+
+               assert_eq!(route.paths[0][2].pubkey, nodes[3]);
+               assert_eq!(route.paths[0][2].short_channel_id, 5);
+               assert_eq!(route.paths[0][2].fee_msat, 0);
+               assert_eq!(route.paths[0][2].cltv_expiry_delta, 2049);
+               assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(4));
+               assert_eq!(route.paths[0][2].channel_features.le_flags(), &Vec::<u8>::new());
+
+               assert_eq!(route.paths[0][3].pubkey, nodes[6]);
+               assert_eq!(route.paths[0][3].short_channel_id, 8);
+               assert_eq!(route.paths[0][3].fee_msat, 100);
+               assert_eq!(route.paths[0][3].cltv_expiry_delta, 42);
+               assert_eq!(route.paths[0][3].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
+               assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
+       }
+
+       fn last_hops_with_public_channel(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
+               let zero_fees = RoutingFees {
+                       base_msat: 0,
+                       proportional_millionths: 0,
+               };
+               vec![RouteHint(vec![RouteHintHop {
+                       src_node_id: nodes[4].clone(),
+                       short_channel_id: 11,
+                       fees: zero_fees,
+                       cltv_expiry_delta: (11 << 8) | 1,
+                       htlc_minimum_msat: None,
+                       htlc_maximum_msat: None,
+               }, RouteHintHop {
+                       src_node_id: nodes[3].clone(),
+                       short_channel_id: 8,
+                       fees: zero_fees,
+                       cltv_expiry_delta: (8 << 8) | 1,
+                       htlc_minimum_msat: None,
+                       htlc_maximum_msat: None,
+               }]), RouteHint(vec![RouteHintHop {
+                       src_node_id: nodes[4].clone(),
+                       short_channel_id: 9,
+                       fees: RoutingFees {
+                               base_msat: 1001,
+                               proportional_millionths: 0,
+                       },
+                       cltv_expiry_delta: (9 << 8) | 1,
+                       htlc_minimum_msat: None,
+                       htlc_maximum_msat: None,
+               }]), RouteHint(vec![RouteHintHop {
+                       src_node_id: nodes[5].clone(),
+                       short_channel_id: 10,
+                       fees: zero_fees,
+                       cltv_expiry_delta: (10 << 8) | 1,
+                       htlc_minimum_msat: None,
+                       htlc_maximum_msat: None,
+               }])]
+       }
+
+       #[test]
+       fn last_hops_with_public_channel_test() {
+               let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
+               let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
+               // This test shows that public routes can be present in the invoice
+               // which would be handled in the same manner.
+
+               let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &last_hops_with_public_channel(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
+               assert_eq!(route.paths[0].len(), 5);
+
+               assert_eq!(route.paths[0][0].pubkey, nodes[1]);
+               assert_eq!(route.paths[0][0].short_channel_id, 2);
+               assert_eq!(route.paths[0][0].fee_msat, 100);
+               assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
+               assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
+               assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
+
+               assert_eq!(route.paths[0][1].pubkey, nodes[2]);
+               assert_eq!(route.paths[0][1].short_channel_id, 4);
+               assert_eq!(route.paths[0][1].fee_msat, 0);
+               assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
+               assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
+               assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
+
+               assert_eq!(route.paths[0][2].pubkey, nodes[4]);
+               assert_eq!(route.paths[0][2].short_channel_id, 6);
+               assert_eq!(route.paths[0][2].fee_msat, 0);
+               assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
+               assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
+               assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
+
+               assert_eq!(route.paths[0][3].pubkey, nodes[3]);
+               assert_eq!(route.paths[0][3].short_channel_id, 11);
+               assert_eq!(route.paths[0][3].fee_msat, 0);
+               assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
+               // If we have a peer in the node map, we'll use their features here since we don't have
+               // a way of figuring out their features from the invoice:
+               assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
+               assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new());
+
+               assert_eq!(route.paths[0][4].pubkey, nodes[6]);
+               assert_eq!(route.paths[0][4].short_channel_id, 8);
+               assert_eq!(route.paths[0][4].fee_msat, 100);
+               assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
+               assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
+               assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
+       }
+
        #[test]
        fn our_chans_last_hop_connect_test() {
                let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();