Implement routing to blinded payment paths
authorValentine Wallace <vwallace@protonmail.com>
Wed, 14 Jun 2023 22:14:29 +0000 (18:14 -0400)
committerValentine Wallace <vwallace@protonmail.com>
Mon, 19 Jun 2023 13:54:25 +0000 (09:54 -0400)
Sending to them is still disallowed, for now.

lightning/src/routing/router.rs

index fa0c58a889b49854f00266864393b7fc033b3b10..7342e813a9ed906d4f6a45412203106a7445c59e 100644 (file)
@@ -795,6 +795,19 @@ impl Payee {
                        _ => None,
                }
        }
+       fn blinded_route_hints(&self) -> &[(BlindedPayInfo, BlindedPath)] {
+               match self {
+                       Self::Blinded { route_hints, .. } => &route_hints[..],
+                       Self::Clear { .. } => &[]
+               }
+       }
+
+       fn unblinded_route_hints(&self) -> &[RouteHint] {
+               match self {
+                       Self::Blinded { .. } => &[],
+                       Self::Clear { route_hints, .. } => &route_hints[..]
+               }
+       }
 }
 
 enum FeaturesRef<'a> {
@@ -1042,6 +1055,14 @@ impl<'a> CandidateRouteHop<'a> {
                        _ => CandidateHopId::Clear((self.short_channel_id().unwrap(), channel_direction)),
                }
        }
+       fn blinded_path(&self) -> Option<&'a BlindedPath> {
+               match self {
+                       CandidateRouteHop::Blinded { hint, .. } | CandidateRouteHop::OneHopBlinded { hint, .. } => {
+                               Some(&hint.1)
+                       },
+                       _ => None,
+               }
+       }
 }
 
 #[derive(Clone, Copy, Eq, Hash, Ord, PartialOrd, PartialEq)]
@@ -1424,8 +1445,23 @@ where L::Target: Logger {
                                }
                        }
                },
-               _ => return Err(LightningError{err: "Routing to blinded paths isn't supported yet".to_owned(), action: ErrorAction::IgnoreError}),
-
+               Payee::Blinded { route_hints, .. } => {
+                       if route_hints.iter().all(|(_, path)| &path.introduction_node_id == our_node_pubkey) {
+                               return Err(LightningError{err: "Cannot generate a route to blinded paths if we are the introduction node to all of them".to_owned(), action: ErrorAction::IgnoreError});
+                       }
+                       for (_, blinded_path) in route_hints.iter() {
+                               if blinded_path.blinded_hops.len() == 0 {
+                                       return Err(LightningError{err: "0-hop blinded path provided".to_owned(), action: ErrorAction::IgnoreError});
+                               } else if &blinded_path.introduction_node_id == our_node_pubkey {
+                                       log_info!(logger, "Got blinded path with ourselves as the introduction node, ignoring");
+                               } else if blinded_path.blinded_hops.len() == 1 &&
+                                       route_hints.iter().any( |(_, p)| p.blinded_hops.len() == 1
+                                               && p.introduction_node_id != blinded_path.introduction_node_id)
+                               {
+                                       return Err(LightningError{err: format!("1-hop blinded paths must all have matching introduction node ids"), action: ErrorAction::IgnoreError});
+                               }
+                       }
+               }
        }
        let final_cltv_expiry_delta = payment_params.payee.final_cltv_expiry_delta().unwrap_or(0);
        if payment_params.max_total_cltv_expiry_delta <= final_cltv_expiry_delta {
@@ -1932,11 +1968,37 @@ where L::Target: Logger {
                // 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.
-               let route_hints = match &payment_params.payee {
-                       Payee::Clear { route_hints, .. } => route_hints,
-                       _ => return Err(LightningError{err: "Routing to blinded paths isn't supported yet".to_owned(), action: ErrorAction::IgnoreError}),
-               };
-               for route in route_hints.iter().filter(|route| !route.0.is_empty()) {
+               for (hint_idx, hint) in payment_params.payee.blinded_route_hints().iter().enumerate() {
+                       let intro_node_id = NodeId::from_pubkey(&hint.1.introduction_node_id);
+                       let have_intro_node_in_graph =
+                               // 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(&intro_node_id).is_some() ||
+                               network_nodes.get(&intro_node_id).is_some();
+                       if !have_intro_node_in_graph { continue }
+                       let candidate = if hint.1.blinded_hops.len() == 1 {
+                               CandidateRouteHop::OneHopBlinded { hint, hint_idx }
+                       } else { CandidateRouteHop::Blinded { hint, hint_idx } };
+                       let mut path_contribution_msat = path_value_msat;
+                       if let Some(hop_used_msat) = add_entry!(candidate, intro_node_id, maybe_dummy_payee_node_id,
+                               0, path_contribution_msat, 0, 0_u64, 0, 0)
+                       {
+                               path_contribution_msat = hop_used_msat;
+                       } else { continue }
+                       if let Some(first_channels) = first_hop_targets.get_mut(&NodeId::from_pubkey(&hint.1.introduction_node_id)) {
+                               sort_first_hop_channels(first_channels, &used_liquidities, recommended_value_msat,
+                                       our_node_pubkey);
+                               for details in first_channels {
+                                       let first_hop_candidate = CandidateRouteHop::FirstHop { details };
+                                       add_entry!(first_hop_candidate, our_node_id, intro_node_id, 0, path_contribution_msat, 0,
+                                               0_u64, 0, 0);
+                               }
+                       }
+               }
+               for route in payment_params.payee.unblinded_route_hints().iter()
+                       .filter(|route| !route.0.is_empty())
+               {
                        let first_hop_in_route = &(route.0)[0];
                        let have_hop_src_in_graph =
                                // Only add the hops in this route to our candidate set if either
@@ -2325,8 +2387,8 @@ where L::Target: Logger {
        });
        for idx in 0..(selected_route.len() - 1) {
                if idx + 1 >= selected_route.len() { break; }
-               if iter_equal(selected_route[idx    ].hops.iter().map(|h| (h.0.candidate.short_channel_id(), h.0.node_id)),
-                             selected_route[idx + 1].hops.iter().map(|h| (h.0.candidate.short_channel_id(), h.0.node_id))) {
+               if iter_equal(selected_route[idx    ].hops.iter().map(|h| (h.0.candidate.id(true), h.0.node_id)),
+                             selected_route[idx + 1].hops.iter().map(|h| (h.0.candidate.id(true), h.0.node_id))) {
                        let new_value = selected_route[idx].get_value_msat() + selected_route[idx + 1].get_value_msat();
                        selected_route[idx].update_value_and_recompute_fees(new_value);
                        selected_route.remove(idx + 1);
@@ -2348,12 +2410,25 @@ where L::Target: Logger {
                                cltv_expiry_delta: hop.candidate.cltv_expiry_delta(),
                        });
                }
+               let mut final_cltv_delta = final_cltv_expiry_delta;
+               let blinded_tail = payment_path.hops.last().and_then(|(h, _)| {
+                       if let Some(blinded_path) = h.candidate.blinded_path() {
+                               final_cltv_delta = h.candidate.cltv_expiry_delta();
+                               Some(BlindedTail {
+                                       hops: blinded_path.blinded_hops.clone(),
+                                       blinding_point: blinded_path.blinding_point,
+                                       excess_final_cltv_expiry_delta: 0,
+                                       final_value_msat: h.fee_msat,
+                               })
+                       } else { None }
+               });
                // Propagate the cltv_expiry_delta one hop backwards since the delta from the current hop is
                // applicable for the previous hop.
-               hops.iter_mut().rev().fold(final_cltv_expiry_delta, |prev_cltv_expiry_delta, hop| {
+               hops.iter_mut().rev().fold(final_cltv_delta, |prev_cltv_expiry_delta, hop| {
                        core::mem::replace(&mut hop.cltv_expiry_delta, prev_cltv_expiry_delta)
                });
-               paths.push(Path { hops, blinded_tail: None });
+
+               paths.push(Path { hops, blinded_tail });
        }
        // Make sure we would never create a route with more paths than we allow.
        debug_assert!(paths.len() <= payment_params.max_path_count.into());
@@ -2550,9 +2625,10 @@ mod tests {
        use crate::routing::test_utils::{add_channel, add_or_update_node, build_graph, build_line_graph, id_to_feature_flags, get_nodes, update_channel};
        use crate::chain::transaction::OutPoint;
        use crate::sign::EntropySource;
-       use crate::ln::features::{ChannelFeatures, InitFeatures, NodeFeatures};
+       use crate::ln::features::{BlindedHopFeatures, Bolt12InvoiceFeatures, ChannelFeatures, InitFeatures, NodeFeatures};
        use crate::ln::msgs::{ErrorAction, LightningError, UnsignedChannelUpdate, MAX_VALUE_MSAT};
        use crate::ln::channelmanager;
+       use crate::offers::invoice::BlindedPayInfo;
        use crate::util::config::UserConfig;
        use crate::util::test_utils as ln_test_utils;
        use crate::util::chacha20::ChaCha20;
@@ -4219,14 +4295,66 @@ mod tests {
 
        #[test]
        fn simple_mpp_route_test() {
+               let (secp_ctx, _, _, _, _) = build_graph();
+               let (_, _, _, nodes) = get_nodes(&secp_ctx);
+               let config = UserConfig::default();
+               let clear_payment_params = PaymentParameters::from_node_id(nodes[2], 42)
+                       .with_bolt11_features(channelmanager::provided_invoice_features(&config)).unwrap();
+               do_simple_mpp_route_test(clear_payment_params);
+
+               // MPP to a 1-hop blinded path for nodes[2]
+               let bolt12_features: Bolt12InvoiceFeatures = channelmanager::provided_invoice_features(&config).to_context();
+               let blinded_path = BlindedPath {
+                       introduction_node_id: nodes[2],
+                       blinding_point: ln_test_utils::pubkey(42),
+                       blinded_hops: vec![BlindedHop { blinded_node_id: ln_test_utils::pubkey(42 as u8), encrypted_payload: Vec::new() }],
+               };
+               let blinded_payinfo = BlindedPayInfo { // These fields are ignored for 1-hop blinded paths
+                       fee_base_msat: 0,
+                       fee_proportional_millionths: 0,
+                       htlc_minimum_msat: 0,
+                       htlc_maximum_msat: 0,
+                       cltv_expiry_delta: 0,
+                       features: BlindedHopFeatures::empty(),
+               };
+               let one_hop_blinded_payment_params = PaymentParameters::blinded(vec![(blinded_payinfo.clone(), blinded_path.clone())])
+                       .with_bolt12_features(bolt12_features.clone()).unwrap();
+               do_simple_mpp_route_test(one_hop_blinded_payment_params.clone());
+
+               // MPP to 3 2-hop blinded paths
+               let mut blinded_path_node_0 = blinded_path.clone();
+               blinded_path_node_0.introduction_node_id = nodes[0];
+               blinded_path_node_0.blinded_hops.push(blinded_path.blinded_hops[0].clone());
+               let mut node_0_payinfo = blinded_payinfo.clone();
+               node_0_payinfo.htlc_maximum_msat = 50_000;
+
+               let mut blinded_path_node_7 = blinded_path_node_0.clone();
+               blinded_path_node_7.introduction_node_id = nodes[7];
+               let mut node_7_payinfo = blinded_payinfo.clone();
+               node_7_payinfo.htlc_maximum_msat = 60_000;
+
+               let mut blinded_path_node_1 = blinded_path_node_0.clone();
+               blinded_path_node_1.introduction_node_id = nodes[1];
+               let mut node_1_payinfo = blinded_payinfo.clone();
+               node_1_payinfo.htlc_maximum_msat = 180_000;
+
+               let two_hop_blinded_payment_params = PaymentParameters::blinded(
+                       vec![
+                               (node_0_payinfo, blinded_path_node_0),
+                               (node_7_payinfo, blinded_path_node_7),
+                               (node_1_payinfo, blinded_path_node_1)
+                       ])
+                       .with_bolt12_features(bolt12_features).unwrap();
+               do_simple_mpp_route_test(two_hop_blinded_payment_params);
+       }
+
+
+       fn do_simple_mpp_route_test(payment_params: PaymentParameters) {
                let (secp_ctx, network_graph, gossip_sync, _, logger) = build_graph();
                let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
                let scorer = ln_test_utils::TestScorer::new();
                let keys_manager = ln_test_utils::TestKeysInterface::new(&[0u8; 32], Network::Testnet);
                let random_seed_bytes = keys_manager.get_secure_random_bytes();
-               let config = UserConfig::default();
-               let payment_params = PaymentParameters::from_node_id(nodes[2], 42)
-                       .with_bolt11_features(channelmanager::provided_invoice_features(&config)).unwrap();
 
                // We need a route consisting of 3 paths:
                // From our node to node2 via node0, node7, node1 (three paths one hop each).
@@ -4355,8 +4483,12 @@ mod tests {
                        assert_eq!(route.paths.len(), 3);
                        let mut total_amount_paid_msat = 0;
                        for path in &route.paths {
-                               assert_eq!(path.hops.len(), 2);
-                               assert_eq!(path.hops.last().unwrap().pubkey, nodes[2]);
+                               if let Some(bt) = &path.blinded_tail {
+                                       assert_eq!(path.hops.len() + if bt.hops.len() == 1 { 0 } else { 1 }, 2);
+                               } else {
+                                       assert_eq!(path.hops.len(), 2);
+                                       assert_eq!(path.hops.last().unwrap().pubkey, nodes[2]);
+                               }
                                total_amount_paid_msat += path.final_value_msat();
                        }
                        assert_eq!(total_amount_paid_msat, 250_000);
@@ -4369,8 +4501,22 @@ mod tests {
                        assert_eq!(route.paths.len(), 3);
                        let mut total_amount_paid_msat = 0;
                        for path in &route.paths {
-                               assert_eq!(path.hops.len(), 2);
-                               assert_eq!(path.hops.last().unwrap().pubkey, nodes[2]);
+                               if payment_params.payee.blinded_route_hints().len() != 0 {
+                                       assert!(path.blinded_tail.is_some()) } else { assert!(path.blinded_tail.is_none()) }
+                               if let Some(bt) = &path.blinded_tail {
+                                       assert_eq!(path.hops.len() + if bt.hops.len() == 1 { 0 } else { 1 }, 2);
+                                       if bt.hops.len() > 1 {
+                                               assert_eq!(path.hops.last().unwrap().pubkey,
+                                                       payment_params.payee.blinded_route_hints().iter()
+                                                               .find(|(p, _)| p.htlc_maximum_msat == path.final_value_msat())
+                                                               .map(|(_, p)| p.introduction_node_id).unwrap());
+                                       } else {
+                                               assert_eq!(path.hops.last().unwrap().pubkey, nodes[2]);
+                                       }
+                               } else {
+                                       assert_eq!(path.hops.len(), 2);
+                                       assert_eq!(path.hops.last().unwrap().pubkey, nodes[2]);
+                               }
                                total_amount_paid_msat += path.final_value_msat();
                        }
                        assert_eq!(total_amount_paid_msat, 290_000);
@@ -6152,6 +6298,36 @@ mod tests {
                assert!(route.paths[0].hops.last().unwrap().fee_msat <= max_htlc_msat);
                assert!(route.paths[1].hops.last().unwrap().fee_msat <= max_htlc_msat);
                assert_eq!(route.get_total_amount(), amt_msat);
+
+               // Make sure this works for blinded route hints.
+               let blinded_path = BlindedPath {
+                       introduction_node_id: intermed_node_id,
+                       blinding_point: ln_test_utils::pubkey(42),
+                       blinded_hops: vec![
+                               BlindedHop { blinded_node_id: ln_test_utils::pubkey(42), encrypted_payload: vec![] },
+                               BlindedHop { blinded_node_id: ln_test_utils::pubkey(43), encrypted_payload: vec![] },
+                       ],
+               };
+               let blinded_payinfo = BlindedPayInfo {
+                       fee_base_msat: 100,
+                       fee_proportional_millionths: 0,
+                       htlc_minimum_msat: 1,
+                       htlc_maximum_msat: max_htlc_msat,
+                       cltv_expiry_delta: 10,
+                       features: BlindedHopFeatures::empty(),
+               };
+               let bolt12_features: Bolt12InvoiceFeatures = channelmanager::provided_invoice_features(&config).to_context();
+               let payment_params = PaymentParameters::blinded(vec![
+                       (blinded_payinfo.clone(), blinded_path.clone()),
+                       (blinded_payinfo.clone(), blinded_path.clone())])
+                       .with_bolt12_features(bolt12_features).unwrap();
+               let route = get_route(&our_node_id, &payment_params, &network_graph.read_only(),
+                       Some(&first_hops.iter().collect::<Vec<_>>()), amt_msat, Arc::clone(&logger), &scorer, &(),
+                       &random_seed_bytes).unwrap();
+               assert_eq!(route.paths.len(), 2);
+               assert!(route.paths[0].hops.last().unwrap().fee_msat <= max_htlc_msat);
+               assert!(route.paths[1].hops.last().unwrap().fee_msat <= max_htlc_msat);
+               assert_eq!(route.get_total_amount(), amt_msat);
        }
 
        #[test]
@@ -6298,6 +6474,190 @@ mod tests {
                assert_eq!(route.paths[0].blinded_tail.as_ref().unwrap().excess_final_cltv_expiry_delta, 40);
                assert_eq!(route.paths[0].hops.last().unwrap().cltv_expiry_delta, 40);
        }
+
+       #[test]
+       fn simple_blinded_route_hints() {
+               do_simple_blinded_route_hints(1);
+               do_simple_blinded_route_hints(2);
+               do_simple_blinded_route_hints(3);
+       }
+
+       fn do_simple_blinded_route_hints(num_blinded_hops: usize) {
+               // Check that we can generate a route to a blinded path with the expected hops.
+               let (secp_ctx, network, _, _, logger) = build_graph();
+               let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
+               let network_graph = network.read_only();
+
+               let scorer = ln_test_utils::TestScorer::new();
+               let keys_manager = ln_test_utils::TestKeysInterface::new(&[0u8; 32], Network::Testnet);
+               let random_seed_bytes = keys_manager.get_secure_random_bytes();
+
+               let mut blinded_path = BlindedPath {
+                       introduction_node_id: nodes[2],
+                       blinding_point: ln_test_utils::pubkey(42),
+                       blinded_hops: Vec::with_capacity(num_blinded_hops),
+               };
+               for i in 0..num_blinded_hops {
+                       blinded_path.blinded_hops.push(
+                               BlindedHop { blinded_node_id: ln_test_utils::pubkey(42 + i as u8), encrypted_payload: Vec::new() },
+                       );
+               }
+               let blinded_payinfo = BlindedPayInfo {
+                       fee_base_msat: 100,
+                       fee_proportional_millionths: 500,
+                       htlc_minimum_msat: 1000,
+                       htlc_maximum_msat: 100_000_000,
+                       cltv_expiry_delta: 15,
+                       features: BlindedHopFeatures::empty(),
+               };
+
+               let final_amt_msat = 1001;
+               let payment_params = PaymentParameters::blinded(vec![(blinded_payinfo.clone(), blinded_path.clone())]);
+               let route = get_route(&our_id, &payment_params, &network_graph, None, final_amt_msat , Arc::clone(&logger),
+                       &scorer, &(), &random_seed_bytes).unwrap();
+               assert_eq!(route.paths.len(), 1);
+               assert_eq!(route.paths[0].hops.len(), 2);
+
+               let tail = route.paths[0].blinded_tail.as_ref().unwrap();
+               assert_eq!(tail.hops, blinded_path.blinded_hops);
+               assert_eq!(tail.excess_final_cltv_expiry_delta, 0);
+               assert_eq!(tail.final_value_msat, 1001);
+
+               let final_hop = route.paths[0].hops.last().unwrap();
+               assert_eq!(final_hop.pubkey, blinded_path.introduction_node_id);
+               if tail.hops.len() > 1 {
+                       assert_eq!(final_hop.fee_msat,
+                               blinded_payinfo.fee_base_msat as u64 + blinded_payinfo.fee_proportional_millionths as u64 * tail.final_value_msat / 1000000);
+                       assert_eq!(final_hop.cltv_expiry_delta, blinded_payinfo.cltv_expiry_delta as u32);
+               } else {
+                       assert_eq!(final_hop.fee_msat, 0);
+                       assert_eq!(final_hop.cltv_expiry_delta, 0);
+               }
+       }
+
+       #[test]
+       fn blinded_path_routing_errors() {
+               // Check that we can generate a route to a blinded path with the expected hops.
+               let (secp_ctx, network, _, _, logger) = build_graph();
+               let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
+               let network_graph = network.read_only();
+
+               let scorer = ln_test_utils::TestScorer::new();
+               let keys_manager = ln_test_utils::TestKeysInterface::new(&[0u8; 32], Network::Testnet);
+               let random_seed_bytes = keys_manager.get_secure_random_bytes();
+
+               let mut invalid_blinded_path = BlindedPath {
+                       introduction_node_id: nodes[2],
+                       blinding_point: ln_test_utils::pubkey(42),
+                       blinded_hops: vec![
+                               BlindedHop { blinded_node_id: ln_test_utils::pubkey(43), encrypted_payload: vec![0; 43] },
+                       ],
+               };
+               let blinded_payinfo = BlindedPayInfo {
+                       fee_base_msat: 100,
+                       fee_proportional_millionths: 500,
+                       htlc_minimum_msat: 1000,
+                       htlc_maximum_msat: 100_000_000,
+                       cltv_expiry_delta: 15,
+                       features: BlindedHopFeatures::empty(),
+               };
+
+               let mut invalid_blinded_path_2 = invalid_blinded_path.clone();
+               invalid_blinded_path_2.introduction_node_id = ln_test_utils::pubkey(45);
+               let payment_params = PaymentParameters::blinded(vec![
+                       (blinded_payinfo.clone(), invalid_blinded_path.clone()),
+                       (blinded_payinfo.clone(), invalid_blinded_path_2)]);
+               match get_route(&our_id, &payment_params, &network_graph, None, 1001, Arc::clone(&logger),
+                       &scorer, &(), &random_seed_bytes)
+               {
+                       Err(LightningError { err, .. }) => {
+                               assert_eq!(err, "1-hop blinded paths must all have matching introduction node ids");
+                       },
+                       _ => panic!("Expected error")
+               }
+
+               invalid_blinded_path.introduction_node_id = our_id;
+               let payment_params = PaymentParameters::blinded(vec![(blinded_payinfo.clone(), invalid_blinded_path.clone())]);
+               match get_route(&our_id, &payment_params, &network_graph, None, 1001, Arc::clone(&logger),
+                       &scorer, &(), &random_seed_bytes)
+               {
+                       Err(LightningError { err, .. }) => {
+                               assert_eq!(err, "Cannot generate a route to blinded paths if we are the introduction node to all of them");
+                       },
+                       _ => panic!("Expected error")
+               }
+
+               invalid_blinded_path.introduction_node_id = ln_test_utils::pubkey(46);
+               invalid_blinded_path.blinded_hops.clear();
+               let payment_params = PaymentParameters::blinded(vec![(blinded_payinfo, invalid_blinded_path)]);
+               match get_route(&our_id, &payment_params, &network_graph, None, 1001, Arc::clone(&logger),
+                       &scorer, &(), &random_seed_bytes)
+               {
+                       Err(LightningError { err, .. }) => {
+                               assert_eq!(err, "0-hop blinded path provided");
+                       },
+                       _ => panic!("Expected error")
+               }
+       }
+
+       #[test]
+       fn matching_intro_node_paths_provided() {
+               // Check that if multiple blinded paths with the same intro node are provided in payment
+               // parameters, we'll return the correct paths in the resulting MPP route.
+               let (secp_ctx, network, _, _, logger) = build_graph();
+               let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
+               let network_graph = network.read_only();
+
+               let scorer = ln_test_utils::TestScorer::new();
+               let keys_manager = ln_test_utils::TestKeysInterface::new(&[0u8; 32], Network::Testnet);
+               let random_seed_bytes = keys_manager.get_secure_random_bytes();
+               let config = UserConfig::default();
+
+               let bolt12_features: Bolt12InvoiceFeatures = channelmanager::provided_invoice_features(&config).to_context();
+               let blinded_path_1 = BlindedPath {
+                       introduction_node_id: nodes[2],
+                       blinding_point: ln_test_utils::pubkey(42),
+                       blinded_hops: vec![
+                               BlindedHop { blinded_node_id: ln_test_utils::pubkey(42 as u8), encrypted_payload: Vec::new() },
+                               BlindedHop { blinded_node_id: ln_test_utils::pubkey(42 as u8), encrypted_payload: Vec::new() }
+                       ],
+               };
+               let blinded_payinfo_1 = BlindedPayInfo {
+                       fee_base_msat: 0,
+                       fee_proportional_millionths: 0,
+                       htlc_minimum_msat: 0,
+                       htlc_maximum_msat: 30_000,
+                       cltv_expiry_delta: 0,
+                       features: BlindedHopFeatures::empty(),
+               };
+
+               let mut blinded_path_2 = blinded_path_1.clone();
+               blinded_path_2.blinding_point = ln_test_utils::pubkey(43);
+               let mut blinded_payinfo_2 = blinded_payinfo_1.clone();
+               blinded_payinfo_2.htlc_maximum_msat = 70_000;
+
+               let blinded_hints = vec![
+                       (blinded_payinfo_1.clone(), blinded_path_1.clone()),
+                       (blinded_payinfo_2.clone(), blinded_path_2.clone()),
+               ];
+               let payment_params = PaymentParameters::blinded(blinded_hints.clone())
+                       .with_bolt12_features(bolt12_features.clone()).unwrap();
+
+               let route = get_route(&our_id, &payment_params, &network_graph, None,
+                       100_000, Arc::clone(&logger), &scorer, &(), &random_seed_bytes).unwrap();
+               assert_eq!(route.paths.len(), 2);
+               let mut total_amount_paid_msat = 0;
+               for path in route.paths.into_iter() {
+                       assert_eq!(path.hops.last().unwrap().pubkey, nodes[2]);
+                       if let Some(bt) = &path.blinded_tail {
+                               assert_eq!(bt.blinding_point,
+                                       blinded_hints.iter().find(|(p, _)| p.htlc_maximum_msat == path.final_value_msat())
+                                               .map(|(_, bp)| bp.blinding_point).unwrap());
+                       } else { panic!(); }
+                       total_amount_paid_msat += path.final_value_msat();
+               }
+               assert_eq!(total_amount_paid_msat, 100_000);
+       }
 }
 
 #[cfg(all(any(test, ldk_bench), not(feature = "no-std")))]