Add utils for creating blinded PaymentParameters
[rust-lightning] / lightning / src / routing / router.rs
index ef6fef0a7eb42ea87b8d0876f0b11f99112d83cb..c8468798eecb4ba955fea2256b66d470f16170cf 100644 (file)
@@ -18,7 +18,7 @@ use crate::ln::PaymentHash;
 use crate::ln::channelmanager::{ChannelDetails, PaymentId};
 use crate::ln::features::{Bolt12InvoiceFeatures, ChannelFeatures, InvoiceFeatures, NodeFeatures};
 use crate::ln::msgs::{DecodeError, ErrorAction, LightningError, MAX_VALUE_MSAT};
-use crate::offers::invoice::BlindedPayInfo;
+use crate::offers::invoice::{BlindedPayInfo, Invoice as Bolt12Invoice};
 use crate::routing::gossip::{DirectedChannelInfo, EffectiveCapacity, ReadOnlyNetworkGraph, NetworkGraph, NodeId, RoutingFees};
 use crate::routing::scoring::{ChannelUsage, LockableScore, Score};
 use crate::util::ser::{Writeable, Readable, ReadableArgs, Writer};
@@ -621,12 +621,53 @@ impl PaymentParameters {
        ///
        /// The `final_cltv_expiry_delta` should match the expected final CLTV delta the recipient has
        /// provided.
-       pub fn for_keysend(payee_pubkey: PublicKey, final_cltv_expiry_delta: u32) -> Self {
-               Self::from_node_id(payee_pubkey, final_cltv_expiry_delta).with_bolt11_features(InvoiceFeatures::for_keysend()).expect("PaymentParameters::from_node_id should always initialize the payee as unblinded")
+       ///
+       /// Note that MPP keysend is not widely supported yet. The `allow_mpp` lets you choose
+       /// whether your router will be allowed to find a multi-part route for this payment. If you
+       /// set `allow_mpp` to true, you should ensure a payment secret is set on send, likely via
+       /// [`RecipientOnionFields::secret_only`].
+       ///
+       /// [`RecipientOnionFields::secret_only`]: crate::ln::channelmanager::RecipientOnionFields::secret_only
+       pub fn for_keysend(payee_pubkey: PublicKey, final_cltv_expiry_delta: u32, allow_mpp: bool) -> Self {
+               Self::from_node_id(payee_pubkey, final_cltv_expiry_delta)
+                       .with_bolt11_features(InvoiceFeatures::for_keysend(allow_mpp))
+                       .expect("PaymentParameters::from_node_id should always initialize the payee as unblinded")
+       }
+
+       /// Creates parameters for paying to a blinded payee from the provided invoice. Sets
+       /// [`Payee::Blinded::route_hints`], [`Payee::Blinded::features`], and
+       /// [`PaymentParameters::expiry_time`].
+       pub fn from_bolt12_invoice(invoice: &Bolt12Invoice) -> Self {
+               Self::blinded(invoice.payment_paths().to_vec())
+                       .with_bolt12_features(invoice.features().clone()).unwrap()
+                       .with_expiry_time(invoice.created_at().as_secs().saturating_add(invoice.relative_expiry().as_secs()))
+       }
+
+       fn blinded(blinded_route_hints: Vec<(BlindedPayInfo, BlindedPath)>) -> Self {
+               Self {
+                       payee: Payee::Blinded { route_hints: blinded_route_hints, features: None },
+                       expiry_time: None,
+                       max_total_cltv_expiry_delta: DEFAULT_MAX_TOTAL_CLTV_EXPIRY_DELTA,
+                       max_path_count: DEFAULT_MAX_PATH_COUNT,
+                       max_channel_saturation_power_of_half: 2,
+                       previously_failed_channels: Vec::new(),
+               }
        }
 
-       /// Includes the payee's features. Errors if the parameters were initialized with blinded payment
-       /// paths.
+       /// Includes the payee's features. Errors if the parameters were not initialized with
+       /// [`PaymentParameters::from_bolt12_invoice`].
+       ///
+       /// This is not exported to bindings users since bindings don't support move semantics
+       pub fn with_bolt12_features(self, features: Bolt12InvoiceFeatures) -> Result<Self, ()> {
+               match self.payee {
+                       Payee::Clear { .. } => Err(()),
+                       Payee::Blinded { route_hints, .. } =>
+                               Ok(Self { payee: Payee::Blinded { route_hints, features: Some(features) }, ..self })
+               }
+       }
+
+       /// Includes the payee's features. Errors if the parameters were initialized with
+       /// [`PaymentParameters::from_bolt12_invoice`].
        ///
        /// This is not exported to bindings users since bindings don't support move semantics
        pub fn with_bolt11_features(self, features: InvoiceFeatures) -> Result<Self, ()> {
@@ -642,7 +683,7 @@ impl PaymentParameters {
        }
 
        /// Includes hints for routing to the payee. Errors if the parameters were initialized with
-       /// blinded payment paths.
+       /// [`PaymentParameters::from_bolt12_invoice`].
        ///
        /// This is not exported to bindings users since bindings don't support move semantics
        pub fn with_route_hints(self, route_hints: Vec<RouteHint>) -> Result<Self, ()> {
@@ -678,7 +719,8 @@ impl PaymentParameters {
                Self { max_path_count, ..self }
        }
 
-       /// Includes a limit for the maximum number of payment paths that may be used.
+       /// Includes a limit for the maximum share of a channel's total capacity that can be sent over, as
+       /// a power of 1/2. See [`PaymentParameters::max_channel_saturation_power_of_half`].
        ///
        /// This is not exported to bindings users since bindings don't support move semantics
        pub fn with_max_channel_saturation_power_of_half(self, max_channel_saturation_power_of_half: u8) -> Self {
@@ -929,7 +971,7 @@ impl<'a> CandidateRouteHop<'a> {
 
        fn htlc_minimum_msat(&self) -> u64 {
                match self {
-                       CandidateRouteHop::FirstHop { .. } => 0,
+                       CandidateRouteHop::FirstHop { details } => details.next_outbound_htlc_minimum_msat,
                        CandidateRouteHop::PublicHop { info, .. } => info.direction().htlc_minimum_msat,
                        CandidateRouteHop::PrivateHop { hint } => hint.htlc_minimum_msat.unwrap_or(0),
                }
@@ -951,7 +993,10 @@ impl<'a> CandidateRouteHop<'a> {
                                liquidity_msat: details.next_outbound_htlc_limit_msat,
                        },
                        CandidateRouteHop::PublicHop { info, .. } => info.effective_capacity(),
-                       CandidateRouteHop::PrivateHop { .. } => EffectiveCapacity::Infinite,
+                       CandidateRouteHop::PrivateHop { hint: RouteHintHop { htlc_maximum_msat: Some(max), .. }} =>
+                               EffectiveCapacity::HintMaxHTLC { amount_msat: *max },
+                       CandidateRouteHop::PrivateHop { hint: RouteHintHop { htlc_maximum_msat: None, .. }} =>
+                               EffectiveCapacity::Infinite,
                }
        }
 }
@@ -963,8 +1008,11 @@ fn max_htlc_from_capacity(capacity: EffectiveCapacity, max_channel_saturation_po
                EffectiveCapacity::ExactLiquidity { liquidity_msat } => liquidity_msat,
                EffectiveCapacity::Infinite => u64::max_value(),
                EffectiveCapacity::Unknown => EffectiveCapacity::Unknown.as_msat(),
-               EffectiveCapacity::MaximumHTLC { amount_msat } =>
+               EffectiveCapacity::AdvertisedMaxHTLC { amount_msat } =>
                        amount_msat.checked_shr(saturation_shift).unwrap_or(0),
+               // Treat htlc_maximum_msat from a route hint as an exact liquidity amount, since the invoice is
+               // expected to have been generated from up-to-date capacity information.
+               EffectiveCapacity::HintMaxHTLC { amount_msat } => amount_msat,
                EffectiveCapacity::Total { capacity_msat, htlc_maximum_msat } =>
                        cmp::min(capacity_msat.checked_shr(saturation_shift).unwrap_or(0), htlc_maximum_msat),
        }
@@ -1192,6 +1240,41 @@ impl fmt::Display for LoggedPayeePubkey {
        }
 }
 
+#[inline]
+fn sort_first_hop_channels(
+       channels: &mut Vec<&ChannelDetails>, used_channel_liquidities: &HashMap<(u64, bool), u64>,
+       recommended_value_msat: u64, our_node_pubkey: &PublicKey
+) {
+       // Sort the first_hops channels to the same node(s) in priority order of which channel we'd
+       // most like to use.
+       //
+       // First, if channels are below `recommended_value_msat`, sort them in descending order,
+       // preferring larger channels to avoid splitting the payment into more MPP parts than is
+       // required.
+       //
+       // Second, because simply always sorting in descending order would always use our largest
+       // available outbound capacity, needlessly fragmenting our available channel capacities,
+       // sort channels above `recommended_value_msat` in ascending order, preferring channels
+       // which have enough, but not too much, capacity for the payment.
+       //
+       // Available outbound balances factor in liquidity already reserved for previously found paths.
+       channels.sort_unstable_by(|chan_a, chan_b| {
+               let chan_a_outbound_limit_msat = chan_a.next_outbound_htlc_limit_msat
+                       .saturating_sub(*used_channel_liquidities.get(&(chan_a.get_outbound_payment_scid().unwrap(),
+                       our_node_pubkey < &chan_a.counterparty.node_id)).unwrap_or(&0));
+               let chan_b_outbound_limit_msat = chan_b.next_outbound_htlc_limit_msat
+                       .saturating_sub(*used_channel_liquidities.get(&(chan_b.get_outbound_payment_scid().unwrap(),
+                       our_node_pubkey < &chan_b.counterparty.node_id)).unwrap_or(&0));
+               if chan_b_outbound_limit_msat < recommended_value_msat || chan_a_outbound_limit_msat < recommended_value_msat {
+                       // Sort in descending order
+                       chan_b_outbound_limit_msat.cmp(&chan_a_outbound_limit_msat)
+               } else {
+                       // Sort in ascending order
+                       chan_a_outbound_limit_msat.cmp(&chan_b_outbound_limit_msat)
+               }
+       });
+}
+
 /// Finds a route from us (payer) to the given target node (payee).
 ///
 /// If the payee provided features in their invoice, they should be provided via `params.payee`.
@@ -1245,7 +1328,7 @@ where L::Target: Logger {
        // unblinded payee id as an option. We also need a non-optional "payee id" for path construction,
        // so use a dummy id for this in the blinded case.
        let payee_node_id_opt = payment_params.payee.node_id().map(|pk| NodeId::from_pubkey(&pk));
-       const DUMMY_BLINDED_PAYEE_ID: [u8; 33] = [42u8; 33];
+       const DUMMY_BLINDED_PAYEE_ID: [u8; 33] = [2; 33];
        let maybe_dummy_payee_pk = payment_params.payee.node_id().unwrap_or_else(|| PublicKey::from_slice(&DUMMY_BLINDED_PAYEE_ID).unwrap());
        let maybe_dummy_payee_node_id = NodeId::from_pubkey(&maybe_dummy_payee_pk);
        let our_node_id = NodeId::from_pubkey(&our_node_pubkey);
@@ -1437,26 +1520,8 @@ where L::Target: Logger {
        let mut already_collected_value_msat = 0;
 
        for (_, channels) in first_hop_targets.iter_mut() {
-               // Sort the first_hops channels to the same node(s) in priority order of which channel we'd
-               // most like to use.
-               //
-               // First, if channels are below `recommended_value_msat`, sort them in descending order,
-               // preferring larger channels to avoid splitting the payment into more MPP parts than is
-               // required.
-               //
-               // Second, because simply always sorting in descending order would always use our largest
-               // available outbound capacity, needlessly fragmenting our available channel capacities,
-               // sort channels above `recommended_value_msat` in ascending order, preferring channels
-               // which have enough, but not too much, capacity for the payment.
-               channels.sort_unstable_by(|chan_a, chan_b| {
-                       if chan_b.next_outbound_htlc_limit_msat < recommended_value_msat || chan_a.next_outbound_htlc_limit_msat < recommended_value_msat {
-                               // Sort in descending order
-                               chan_b.next_outbound_htlc_limit_msat.cmp(&chan_a.next_outbound_htlc_limit_msat)
-                       } else {
-                               // Sort in ascending order
-                               chan_a.next_outbound_htlc_limit_msat.cmp(&chan_b.next_outbound_htlc_limit_msat)
-                       }
-               });
+               sort_first_hop_channels(channels, &used_channel_liquidities, recommended_value_msat,
+                       our_node_pubkey);
        }
 
        log_trace!(logger, "Building path from {} to payer {} for value {} msat.",
@@ -1470,8 +1535,9 @@ where L::Target: Logger {
                ( $candidate: expr, $src_node_id: expr, $dest_node_id: expr, $next_hops_fee_msat: expr,
                        $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr,
                        $next_hops_path_penalty_msat: expr, $next_hops_cltv_delta: expr, $next_hops_path_length: expr ) => { {
-                       // We "return" whether we updated the path at the end, via this:
-                       let mut did_add_update_path_to_src_node = false;
+                       // We "return" whether we updated the path at the end, and how much we can route via
+                       // this channel, via this:
+                       let mut did_add_update_path_to_src_node = None;
                        // Channels to self should not be used. This is more of belt-and-suspenders, because in
                        // practice these cases should be caught earlier:
                        // - for regular channels at channel announcement (TODO)
@@ -1652,7 +1718,7 @@ where L::Target: Logger {
                                                                {
                                                                        old_entry.value_contribution_msat = value_contribution_msat;
                                                                }
-                                                               did_add_update_path_to_src_node = true;
+                                                               did_add_update_path_to_src_node = Some(value_contribution_msat);
                                                        } else if old_entry.was_processed && new_cost < old_cost {
                                                                #[cfg(all(not(ldk_bench), any(test, fuzzing)))]
                                                                {
@@ -1773,7 +1839,7 @@ where L::Target: Logger {
                        for details in first_channels {
                                let candidate = CandidateRouteHop::FirstHop { details };
                                let added = add_entry!(candidate, our_node_id, payee, 0, path_value_msat,
-                                                                       0, 0u64, 0, 0);
+                                                                       0, 0u64, 0, 0).is_some();
                                log_trace!(logger, "{} direct route to payee via SCID {}",
                                                if added { "Added" } else { "Skipped" }, candidate.short_channel_id());
                        }
@@ -1820,6 +1886,7 @@ where L::Target: Logger {
                                let mut aggregate_next_hops_path_penalty_msat: u64 = 0;
                                let mut aggregate_next_hops_cltv_delta: u32 = 0;
                                let mut aggregate_next_hops_path_length: u8 = 0;
+                               let mut aggregate_path_contribution_msat = path_value_msat;
 
                                for (idx, (hop, prev_hop_id)) in hop_iter.zip(prev_hop_iter).enumerate() {
                                        let source = NodeId::from_pubkey(&hop.src_node_id);
@@ -1833,10 +1900,13 @@ where L::Target: Logger {
                                                })
                                                .unwrap_or_else(|| CandidateRouteHop::PrivateHop { hint: hop });
 
-                                       if !add_entry!(candidate, source, target, aggregate_next_hops_fee_msat,
-                                                               path_value_msat, aggregate_next_hops_path_htlc_minimum_msat,
-                                                               aggregate_next_hops_path_penalty_msat,
-                                                               aggregate_next_hops_cltv_delta, aggregate_next_hops_path_length) {
+                                       if let Some(hop_used_msat) = add_entry!(candidate, source, target,
+                                               aggregate_next_hops_fee_msat, aggregate_path_contribution_msat,
+                                               aggregate_next_hops_path_htlc_minimum_msat, aggregate_next_hops_path_penalty_msat,
+                                               aggregate_next_hops_cltv_delta, aggregate_next_hops_path_length)
+                                       {
+                                               aggregate_path_contribution_msat = hop_used_msat;
+                                       } else {
                                                // 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.
@@ -1863,14 +1933,15 @@ where L::Target: Logger {
                                                .saturating_add(1);
 
                                        // Searching for a direct channel between last checked hop and first_hop_targets
-                                       if let Some(first_channels) = first_hop_targets.get(&NodeId::from_pubkey(&prev_hop_id)) {
+                                       if let Some(first_channels) = first_hop_targets.get_mut(&NodeId::from_pubkey(&prev_hop_id)) {
+                                               sort_first_hop_channels(first_channels, &used_channel_liquidities,
+                                                       recommended_value_msat, our_node_pubkey);
                                                for details in first_channels {
-                                                       let candidate = CandidateRouteHop::FirstHop { details };
-                                                       add_entry!(candidate, our_node_id, NodeId::from_pubkey(&prev_hop_id),
-                                                               aggregate_next_hops_fee_msat, path_value_msat,
-                                                               aggregate_next_hops_path_htlc_minimum_msat,
-                                                               aggregate_next_hops_path_penalty_msat, aggregate_next_hops_cltv_delta,
-                                                               aggregate_next_hops_path_length);
+                                                       let first_hop_candidate = CandidateRouteHop::FirstHop { details };
+                                                       add_entry!(first_hop_candidate, our_node_id, NodeId::from_pubkey(&prev_hop_id),
+                                                               aggregate_next_hops_fee_msat, aggregate_path_contribution_msat,
+                                                               aggregate_next_hops_path_htlc_minimum_msat, aggregate_next_hops_path_penalty_msat,
+                                                               aggregate_next_hops_cltv_delta, aggregate_next_hops_path_length);
                                                }
                                        }
 
@@ -1903,12 +1974,15 @@ where L::Target: Logger {
                                                // 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(first_channels) = first_hop_targets.get(&NodeId::from_pubkey(&hop.src_node_id)) {
+                                               if let Some(first_channels) = first_hop_targets.get_mut(&NodeId::from_pubkey(&hop.src_node_id)) {
+                                                       sort_first_hop_channels(first_channels, &used_channel_liquidities,
+                                                               recommended_value_msat, our_node_pubkey);
                                                        for details in first_channels {
-                                                               let candidate = CandidateRouteHop::FirstHop { details };
-                                                               add_entry!(candidate, our_node_id,
+                                                               let first_hop_candidate = CandidateRouteHop::FirstHop { details };
+                                                               add_entry!(first_hop_candidate, our_node_id,
                                                                        NodeId::from_pubkey(&hop.src_node_id),
-                                                                       aggregate_next_hops_fee_msat, path_value_msat,
+                                                                       aggregate_next_hops_fee_msat,
+                                                                       aggregate_path_contribution_msat,
                                                                        aggregate_next_hops_path_htlc_minimum_msat,
                                                                        aggregate_next_hops_path_penalty_msat,
                                                                        aggregate_next_hops_cltv_delta,
@@ -2460,6 +2534,7 @@ mod tests {
                        balance_msat: 0,
                        outbound_capacity_msat,
                        next_outbound_htlc_limit_msat: outbound_capacity_msat,
+                       next_outbound_htlc_minimum_msat: 0,
                        inbound_capacity_msat: 42,
                        unspendable_punishment_reserve: None,
                        confirmations_required: None,
@@ -5892,6 +5967,127 @@ mod tests {
                assert!(route.is_ok());
        }
 
+       #[test]
+       fn abide_by_route_hint_max_htlc() {
+               // Check that we abide by any htlc_maximum_msat provided in the route hints of the payment
+               // params in the final route.
+               let (secp_ctx, network_graph, _, _, logger) = build_graph();
+               let netgraph = network_graph.read_only();
+               let (_, our_id, _, 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 max_htlc_msat = 50_000;
+               let route_hint_1 = RouteHint(vec![RouteHintHop {
+                       src_node_id: nodes[2],
+                       short_channel_id: 42,
+                       fees: RoutingFees {
+                               base_msat: 100,
+                               proportional_millionths: 0,
+                       },
+                       cltv_expiry_delta: 10,
+                       htlc_minimum_msat: None,
+                       htlc_maximum_msat: Some(max_htlc_msat),
+               }]);
+               let dest_node_id = ln_test_utils::pubkey(42);
+               let payment_params = PaymentParameters::from_node_id(dest_node_id, 42)
+                       .with_route_hints(vec![route_hint_1.clone()]).unwrap()
+                       .with_bolt11_features(channelmanager::provided_invoice_features(&config)).unwrap();
+
+               // Make sure we'll error if our route hints don't have enough liquidity according to their
+               // htlc_maximum_msat.
+               if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id,
+                       &payment_params, &netgraph, None, max_htlc_msat + 1, Arc::clone(&logger), &scorer, &(),
+                       &random_seed_bytes)
+               {
+                       assert_eq!(err, "Failed to find a sufficient route to the given destination");
+               } else { panic!(); }
+
+               // Make sure we'll split an MPP payment across route hints if their htlc_maximum_msat warrants.
+               let mut route_hint_2 = route_hint_1.clone();
+               route_hint_2.0[0].short_channel_id = 43;
+               let payment_params = PaymentParameters::from_node_id(dest_node_id, 42)
+                       .with_route_hints(vec![route_hint_1, route_hint_2]).unwrap()
+                       .with_bolt11_features(channelmanager::provided_invoice_features(&config)).unwrap();
+               let route = get_route(&our_id, &payment_params, &netgraph, None, max_htlc_msat + 1,
+                       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);
+       }
+
+       #[test]
+       fn direct_channel_to_hints_with_max_htlc() {
+               // Check that if we have a first hop channel peer that's connected to multiple provided route
+               // hints, that we properly split the payment between the route hints if needed.
+               let logger = Arc::new(ln_test_utils::TestLogger::new());
+               let network_graph = Arc::new(NetworkGraph::new(Network::Testnet, Arc::clone(&logger)));
+               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 our_node_id = ln_test_utils::pubkey(42);
+               let intermed_node_id = ln_test_utils::pubkey(43);
+               let first_hop = vec![get_channel_details(Some(42), intermed_node_id, InitFeatures::from_le_bytes(vec![0b11]), 10_000_000)];
+
+               let amt_msat = 900_000;
+               let max_htlc_msat = 500_000;
+               let route_hint_1 = RouteHint(vec![RouteHintHop {
+                       src_node_id: intermed_node_id,
+                       short_channel_id: 44,
+                       fees: RoutingFees {
+                               base_msat: 100,
+                               proportional_millionths: 0,
+                       },
+                       cltv_expiry_delta: 10,
+                       htlc_minimum_msat: None,
+                       htlc_maximum_msat: Some(max_htlc_msat),
+               }, RouteHintHop {
+                       src_node_id: intermed_node_id,
+                       short_channel_id: 45,
+                       fees: RoutingFees {
+                               base_msat: 100,
+                               proportional_millionths: 0,
+                       },
+                       cltv_expiry_delta: 10,
+                       htlc_minimum_msat: None,
+                       // Check that later route hint max htlcs don't override earlier ones
+                       htlc_maximum_msat: Some(max_htlc_msat - 50),
+               }]);
+               let mut route_hint_2 = route_hint_1.clone();
+               route_hint_2.0[0].short_channel_id = 46;
+               route_hint_2.0[1].short_channel_id = 47;
+               let dest_node_id = ln_test_utils::pubkey(44);
+               let payment_params = PaymentParameters::from_node_id(dest_node_id, 42)
+                       .with_route_hints(vec![route_hint_1, route_hint_2]).unwrap()
+                       .with_bolt11_features(channelmanager::provided_invoice_features(&config)).unwrap();
+
+               let route = get_route(&our_node_id, &payment_params, &network_graph.read_only(),
+                       Some(&first_hop.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);
+
+               // Re-run but with two first hop channels connected to the same route hint peers that must be
+               // split between.
+               let first_hops = vec![
+                       get_channel_details(Some(42), intermed_node_id, InitFeatures::from_le_bytes(vec![0b11]), amt_msat - 10),
+                       get_channel_details(Some(43), intermed_node_id, InitFeatures::from_le_bytes(vec![0b11]), amt_msat - 10),
+               ];
+               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]
        fn blinded_route_ser() {
                let blinded_path_1 = BlindedPath {
@@ -6121,6 +6317,7 @@ pub(crate) mod bench_utils {
                        user_channel_id: 0,
                        balance_msat: 10_000_000_000,
                        outbound_capacity_msat: 10_000_000_000,
+                       next_outbound_htlc_minimum_msat: 0,
                        next_outbound_htlc_limit_msat: 10_000_000_000,
                        inbound_capacity_msat: 0,
                        unspendable_punishment_reserve: None,