Merge pull request #1218 from TheBlueMatt/2021-12-minor-bindings-tweaks
[rust-lightning] / lightning / src / routing / router.rs
index 706c353dcd8754b6cf99ce103b0c11687e2dafd6..e49844383bbceee091e9d42b7262416109b2d484 100644 (file)
@@ -17,16 +17,19 @@ use bitcoin::secp256k1::key::PublicKey;
 use ln::channelmanager::ChannelDetails;
 use ln::features::{ChannelFeatures, InvoiceFeatures, NodeFeatures};
 use ln::msgs::{DecodeError, ErrorAction, LightningError, MAX_VALUE_MSAT};
-use routing::network_graph::{NetworkGraph, RoutingFees};
+use routing::scoring::Score;
+use routing::network_graph::{NetworkGraph, NodeId, RoutingFees};
 use util::ser::{Writeable, Readable};
-use util::logger::Logger;
+use util::logger::{Level, Logger};
 
-use std::cmp;
-use std::collections::{HashMap, BinaryHeap};
-use std::ops::Deref;
+use io;
+use prelude::*;
+use alloc::collections::BinaryHeap;
+use core::cmp;
+use core::ops::Deref;
 
 /// A hop in a route
-#[derive(Clone, PartialEq)]
+#[derive(Clone, Debug, Hash, PartialEq, Eq)]
 pub struct RouteHop {
        /// The node_id of the node at this hop.
        pub pubkey: PublicKey,
@@ -47,44 +50,18 @@ pub struct RouteHop {
        pub cltv_expiry_delta: u32,
 }
 
-/// (C-not exported)
-impl Writeable for Vec<RouteHop> {
-       fn write<W: ::util::ser::Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
-               (self.len() as u8).write(writer)?;
-               for hop in self.iter() {
-                       hop.pubkey.write(writer)?;
-                       hop.node_features.write(writer)?;
-                       hop.short_channel_id.write(writer)?;
-                       hop.channel_features.write(writer)?;
-                       hop.fee_msat.write(writer)?;
-                       hop.cltv_expiry_delta.write(writer)?;
-               }
-               Ok(())
-       }
-}
-
-/// (C-not exported)
-impl Readable for Vec<RouteHop> {
-       fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Vec<RouteHop>, DecodeError> {
-               let hops_count: u8 = Readable::read(reader)?;
-               let mut hops = Vec::with_capacity(hops_count as usize);
-               for _ in 0..hops_count {
-                       hops.push(RouteHop {
-                               pubkey: Readable::read(reader)?,
-                               node_features: Readable::read(reader)?,
-                               short_channel_id: Readable::read(reader)?,
-                               channel_features: Readable::read(reader)?,
-                               fee_msat: Readable::read(reader)?,
-                               cltv_expiry_delta: Readable::read(reader)?,
-                       });
-               }
-               Ok(hops)
-       }
-}
+impl_writeable_tlv_based!(RouteHop, {
+       (0, pubkey, required),
+       (2, node_features, required),
+       (4, short_channel_id, required),
+       (6, channel_features, required),
+       (8, fee_msat, required),
+       (10, cltv_expiry_delta, required),
+});
 
 /// A route directs a payment from the sender (us) to the recipient. If the recipient supports MPP,
 /// it can take multiple paths. Each path is composed of one or more hops through the network.
-#[derive(Clone, PartialEq)]
+#[derive(Clone, Hash, PartialEq, Eq)]
 pub struct Route {
        /// The list of routes taken for a single (potentially-)multi-part payment. The pubkey of the
        /// last RouteHop in each path must be the same.
@@ -93,32 +70,204 @@ pub struct Route {
        /// given path is variable, keeping the length of any path to less than 20 should currently
        /// ensure it is viable.
        pub paths: Vec<Vec<RouteHop>>,
+       /// The `payee` parameter passed to [`find_route`].
+       /// This is used by `ChannelManager` to track information which may be required for retries,
+       /// provided back to you via [`Event::PaymentPathFailed`].
+       ///
+       /// [`Event::PaymentPathFailed`]: crate::util::events::Event::PaymentPathFailed
+       pub payee: Option<Payee>,
+}
+
+pub(crate) trait RoutePath {
+       /// Gets the fees for a given path, excluding any excess paid to the recipient.
+       fn get_path_fees(&self) -> u64;
+}
+impl RoutePath for Vec<RouteHop> {
+       fn get_path_fees(&self) -> u64 {
+               // Do not count last hop of each path since that's the full value of the payment
+               self.split_last().map(|(_, path_prefix)| path_prefix).unwrap_or(&[])
+                       .iter().map(|hop| &hop.fee_msat)
+                       .sum()
+       }
+}
+
+impl Route {
+       /// Returns the total amount of fees paid on this [`Route`].
+       ///
+       /// This doesn't include any extra payment made to the recipient, which can happen in excess of
+       /// the amount passed to [`find_route`]'s `params.final_value_msat`.
+       pub fn get_total_fees(&self) -> u64 {
+               self.paths.iter().map(|path| path.get_path_fees()).sum()
+       }
+
+       /// Returns the total amount paid on this [`Route`], excluding the fees.
+       pub fn get_total_amount(&self) -> u64 {
+               return self.paths.iter()
+                       .map(|path| path.split_last().map(|(hop, _)| hop.fee_msat).unwrap_or(0))
+                       .sum();
+       }
 }
 
+const SERIALIZATION_VERSION: u8 = 1;
+const MIN_SERIALIZATION_VERSION: u8 = 1;
+
 impl Writeable for Route {
-       fn write<W: ::util::ser::Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
+       fn write<W: ::util::ser::Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
+               write_ver_prefix!(writer, SERIALIZATION_VERSION, MIN_SERIALIZATION_VERSION);
                (self.paths.len() as u64).write(writer)?;
                for hops in self.paths.iter() {
-                       hops.write(writer)?;
+                       (hops.len() as u8).write(writer)?;
+                       for hop in hops.iter() {
+                               hop.write(writer)?;
+                       }
                }
+               write_tlv_fields!(writer, {
+                       (1, self.payee, option),
+               });
                Ok(())
        }
 }
 
 impl Readable for Route {
-       fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Route, DecodeError> {
+       fn read<R: io::Read>(reader: &mut R) -> Result<Route, DecodeError> {
+               let _ver = read_ver_prefix!(reader, SERIALIZATION_VERSION);
                let path_count: u64 = Readable::read(reader)?;
                let mut paths = Vec::with_capacity(cmp::min(path_count, 128) as usize);
                for _ in 0..path_count {
-                       paths.push(Readable::read(reader)?);
+                       let hop_count: u8 = Readable::read(reader)?;
+                       let mut hops = Vec::with_capacity(hop_count as usize);
+                       for _ in 0..hop_count {
+                               hops.push(Readable::read(reader)?);
+                       }
+                       paths.push(hops);
                }
-               Ok(Route { paths })
+               let mut payee = None;
+               read_tlv_fields!(reader, {
+                       (1, payee, option),
+               });
+               Ok(Route { paths, payee })
        }
 }
 
-/// A channel descriptor which provides a last-hop route to get_route
-#[derive(Clone)]
-pub struct RouteHint {
+/// Parameters needed to find a [`Route`] for paying a [`Payee`].
+///
+/// Passed to [`find_route`] and also provided in [`Event::PaymentPathFailed`] for retrying a failed
+/// payment path.
+///
+/// [`Event::PaymentPathFailed`]: crate::util::events::Event::PaymentPathFailed
+#[derive(Clone, Debug)]
+pub struct RouteParameters {
+       /// The recipient of the failed payment path.
+       pub payee: Payee,
+
+       /// The amount in msats sent on the failed payment path.
+       pub final_value_msat: u64,
+
+       /// The CLTV on the final hop of the failed payment path.
+       pub final_cltv_expiry_delta: u32,
+}
+
+impl_writeable_tlv_based!(RouteParameters, {
+       (0, payee, required),
+       (2, final_value_msat, required),
+       (4, final_cltv_expiry_delta, required),
+});
+
+/// The recipient of a payment.
+#[derive(Clone, Debug, Hash, PartialEq, Eq)]
+pub struct Payee {
+       /// The node id of the payee.
+       pub pubkey: PublicKey,
+
+       /// Features supported by the payee.
+       ///
+       /// May be set from the payee's invoice or via [`for_keysend`]. May be `None` if the invoice
+       /// does not contain any features.
+       ///
+       /// [`for_keysend`]: Self::for_keysend
+       pub features: Option<InvoiceFeatures>,
+
+       /// Hints for routing to the payee, containing channels connecting the payee to public nodes.
+       pub route_hints: Vec<RouteHint>,
+
+       /// Expiration of a payment to the payee, in seconds relative to the UNIX epoch.
+       pub expiry_time: Option<u64>,
+}
+
+impl_writeable_tlv_based!(Payee, {
+       (0, pubkey, required),
+       (2, features, option),
+       (4, route_hints, vec_type),
+       (6, expiry_time, option),
+});
+
+impl Payee {
+       /// Creates a payee with the node id of the given `pubkey`.
+       pub fn from_node_id(pubkey: PublicKey) -> Self {
+               Self {
+                       pubkey,
+                       features: None,
+                       route_hints: vec![],
+                       expiry_time: None,
+               }
+       }
+
+       /// Creates a payee with the node id of the given `pubkey` to use for keysend payments.
+       pub fn for_keysend(pubkey: PublicKey) -> Self {
+               Self::from_node_id(pubkey).with_features(InvoiceFeatures::for_keysend())
+       }
+
+       /// Includes the payee's features.
+       ///
+       /// (C-not exported) since bindings don't support move semantics
+       pub fn with_features(self, features: InvoiceFeatures) -> Self {
+               Self { features: Some(features), ..self }
+       }
+
+       /// Includes hints for routing to the payee.
+       ///
+       /// (C-not exported) since bindings don't support move semantics
+       pub fn with_route_hints(self, route_hints: Vec<RouteHint>) -> Self {
+               Self { route_hints, ..self }
+       }
+
+       /// Includes a payment expiration in seconds relative to the UNIX epoch.
+       ///
+       /// (C-not exported) since bindings don't support move semantics
+       pub fn with_expiry_time(self, expiry_time: u64) -> Self {
+               Self { expiry_time: Some(expiry_time), ..self }
+       }
+}
+
+/// A list of hops along a payment path terminating with a channel to the recipient.
+#[derive(Clone, Debug, Hash, Eq, PartialEq)]
+pub struct RouteHint(pub Vec<RouteHintHop>);
+
+
+impl Writeable for RouteHint {
+       fn write<W: ::util::ser::Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
+               (self.0.len() as u64).write(writer)?;
+               for hop in self.0.iter() {
+                       hop.write(writer)?;
+               }
+               Ok(())
+       }
+}
+
+impl Readable for RouteHint {
+       fn read<R: io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
+               let hop_count: u64 = Readable::read(reader)?;
+               let mut hops = Vec::with_capacity(cmp::min(hop_count, 16) as usize);
+               for _ in 0..hop_count {
+                       hops.push(Readable::read(reader)?);
+               }
+               Ok(Self(hops))
+       }
+}
+
+/// A channel descriptor for a hop along a payment path.
+#[derive(Clone, Debug, Hash, Eq, PartialEq)]
+pub struct RouteHintHop {
        /// The node_id of the non-target end of the route
        pub src_node_id: PublicKey,
        /// The short_channel_id of this channel
@@ -133,9 +282,18 @@ pub struct RouteHint {
        pub htlc_maximum_msat: Option<u64>,
 }
 
+impl_writeable_tlv_based!(RouteHintHop, {
+       (0, src_node_id, required),
+       (1, htlc_minimum_msat, option),
+       (2, short_channel_id, required),
+       (3, htlc_maximum_msat, option),
+       (4, fees, required),
+       (6, cltv_expiry_delta, required),
+});
+
 #[derive(Eq, PartialEq)]
 struct RouteGraphNode {
-       pubkey: PublicKey,
+       node_id: NodeId,
        lowest_fee_to_peer_through_node: u64,
        lowest_fee_to_node: u64,
        // The maximum value a yet-to-be-constructed payment path might flow through this node.
@@ -147,13 +305,20 @@ struct RouteGraphNode {
        /// The effective htlc_minimum_msat at this hop. If a later hop on the path had a higher HTLC
        /// minimum, we use it, plus the fees required at each earlier hop to meet it.
        path_htlc_minimum_msat: u64,
+       /// All penalties incurred from this hop on the way to the destination, as calculated using
+       /// channel scoring.
+       path_penalty_msat: u64,
 }
 
 impl cmp::Ord for RouteGraphNode {
        fn cmp(&self, other: &RouteGraphNode) -> cmp::Ordering {
-               let other_score = cmp::max(other.lowest_fee_to_peer_through_node, other.path_htlc_minimum_msat);
-               let self_score = cmp::max(self.lowest_fee_to_peer_through_node, self.path_htlc_minimum_msat);
-               other_score.cmp(&self_score).then_with(|| other.pubkey.serialize().cmp(&self.pubkey.serialize()))
+               let other_score = cmp::max(other.lowest_fee_to_peer_through_node, other.path_htlc_minimum_msat)
+                       .checked_add(other.path_penalty_msat)
+                       .unwrap_or_else(|| u64::max_value());
+               let self_score = cmp::max(self.lowest_fee_to_peer_through_node, self.path_htlc_minimum_msat)
+                       .checked_add(self.path_penalty_msat)
+                       .unwrap_or_else(|| u64::max_value());
+               other_score.cmp(&self_score).then_with(|| other.node_id.cmp(&self.node_id))
        }
 }
 
@@ -174,11 +339,16 @@ struct DummyDirectionalChannelInfo {
 /// so that we can choose cheaper paths (as per Dijkstra's algorithm).
 /// Fee values should be updated only in the context of the whole path, see update_value_and_recompute_fees.
 /// These fee values are useful to choose hops as we traverse the graph "payee-to-payer".
-#[derive(Clone)]
-struct PathBuildingHop {
-       /// Hop-specific details unrelated to the path during the routing phase,
-       /// but rather relevant to the LN graph.
-       route_hop: RouteHop,
+#[derive(Clone, Debug)]
+struct PathBuildingHop<'a> {
+       // The RouteHintHop fields which will eventually be used if this hop is used in a final Route.
+       // Note that node_features is calculated separately after our initial graph walk.
+       node_id: NodeId,
+       short_channel_id: u64,
+       channel_features: &'a ChannelFeatures,
+       fee_msat: u64,
+       cltv_expiry_delta: u32,
+
        /// Minimal fees required to route to the source node of the current hop via any of its inbound channels.
        src_lowest_inbound_fees: RoutingFees,
        /// Fees of the channel used in this hop.
@@ -200,20 +370,34 @@ struct PathBuildingHop {
        /// A mirror of the same field in RouteGraphNode. Note that this is only used during the graph
        /// walk and may be invalid thereafter.
        path_htlc_minimum_msat: u64,
+       /// All penalties incurred from this channel on the way to the destination, as calculated using
+       /// channel scoring.
+       path_penalty_msat: u64,
+       /// If we've already processed a node as the best node, we shouldn't process it again. Normally
+       /// we'd just ignore it if we did as all channels would have a higher new fee, but because we
+       /// may decrease the amounts in use as we walk the graph, the actual calculated fee may
+       /// decrease as well. Thus, we have to explicitly track which nodes have been processed and
+       /// avoid processing them again.
+       was_processed: bool,
+       #[cfg(any(test, feature = "fuzztarget"))]
+       // In tests, we apply further sanity checks on cases where we skip nodes we already processed
+       // to ensure it is specifically in cases where the fee has gone down because of a decrease in
+       // value_contribution_msat, which requires tracking it here. See comments below where it is
+       // used for more info.
+       value_contribution_msat: u64,
 }
 
 // Instantiated with a list of hops with correct data in them collected during path finding,
 // an instance of this struct should be further modified only via given methods.
 #[derive(Clone)]
-struct PaymentPath {
-       hops: Vec<PathBuildingHop>,
+struct PaymentPath<'a> {
+       hops: Vec<(PathBuildingHop<'a>, NodeFeatures)>,
 }
 
-impl PaymentPath {
-
+impl<'a> PaymentPath<'a> {
        // TODO: Add a value_msat field to PaymentPath and use it instead of this function.
        fn get_value_msat(&self) -> u64 {
-               self.hops.last().unwrap().route_hop.fee_msat
+               self.hops.last().unwrap().0.fee_msat
        }
 
        fn get_total_fee_paid_msat(&self) -> u64 {
@@ -222,9 +406,9 @@ impl PaymentPath {
                }
                let mut result = 0;
                // Can't use next_hops_fee_msat because it gets outdated.
-               for (i, hop) in self.hops.iter().enumerate() {
+               for (i, (hop, _)) in self.hops.iter().enumerate() {
                        if i != self.hops.len() - 1 {
-                               result += hop.route_hop.fee_msat;
+                               result += hop.fee_msat;
                        }
                }
                return result;
@@ -233,16 +417,14 @@ impl PaymentPath {
        // If the amount transferred by the path is updated, the fees should be adjusted. Any other way
        // to change fees may result in an inconsistency.
        //
-       // Sometimes we call this function right after constructing a path which has inconsistent
-       // (in terms of reaching htlc_minimum_msat), so that this function puts the fees in order.
-       // In that case we call it on the "same" amount we initially allocated for this path, and which
-       // could have been reduced on the way. In that case, there is also a risk of exceeding
-       // available_liquidity inside this function, because the function is unaware of this bound.
-       // In our specific recomputation cases where we never increase the value the risk is pretty low.
-       // This function, however, does not support arbitrarily increasing the value being transferred,
-       // and the exception will be triggered.
+       // Sometimes we call this function right after constructing a path which is inconsistent in
+       // that it the value being transferred has decreased while we were doing path finding, leading
+       // to the fees being paid not lining up with the actual limits.
+       //
+       // Note that this function is not aware of the available_liquidity limit, and thus does not
+       // support increasing the value being transferred.
        fn update_value_and_recompute_fees(&mut self, value_msat: u64) {
-               assert!(value_msat <= self.hops.last().unwrap().route_hop.fee_msat);
+               assert!(value_msat <= self.hops.last().unwrap().0.fee_msat);
 
                let mut total_fee_paid_msat = 0 as u64;
                for i in (0..self.hops.len()).rev() {
@@ -253,10 +435,10 @@ impl PaymentPath {
                        // htlc_minimum_msat of the current channel. Last hop is handled separately.
                        let mut cur_hop_fees_msat = 0;
                        if !last_hop {
-                               cur_hop_fees_msat = self.hops.get(i + 1).unwrap().hop_use_fee_msat;
+                               cur_hop_fees_msat = self.hops.get(i + 1).unwrap().0.hop_use_fee_msat;
                        }
 
-                       let mut cur_hop = self.hops.get_mut(i).unwrap();
+                       let mut cur_hop = &mut self.hops.get_mut(i).unwrap().0;
                        cur_hop.next_hops_fee_msat = total_fee_paid_msat;
                        // Overpay in fees if we can't save these funds due to htlc_minimum_msat.
                        // We try to account for htlc_minimum_msat in scoring (add_entry!), so that nodes don't
@@ -280,11 +462,11 @@ impl PaymentPath {
                        if last_hop {
                                // Final hop is a special case: it usually has just value_msat (by design), but also
                                // it still could overpay for the htlc_minimum_msat.
-                               cur_hop.route_hop.fee_msat = cur_hop_transferred_amount_msat;
+                               cur_hop.fee_msat = cur_hop_transferred_amount_msat;
                        } else {
                                // Propagate updated fees for the use of the channels to one hop back, where they
                                // will be actually paid (fee_msat). The last hop is handled above separately.
-                               cur_hop.route_hop.fee_msat = cur_hop_fees_msat;
+                               cur_hop.fee_msat = cur_hop_fees_msat;
                        }
 
                        // Fee for the use of the current hop which will be deducted on the previous hop.
@@ -319,30 +501,55 @@ fn compute_fees(amount_msat: u64, channel_fees: RoutingFees) -> Option<u64> {
        }
 }
 
-/// Gets a route from us (payer) to the given target node (payee).
+/// 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 payee_features.
+/// If the payee provided features in their invoice, they should be provided via `params.payee`.
 /// Without this, MPP will only be used if the payee's features are available in the network graph.
 ///
-/// Extra routing hops between known nodes and the target will be used if they are included in
-/// last_hops.
+/// Private routing paths between a public node and the target may be included in `params.payee`.
+///
+/// If some channels aren't announced, it may be useful to fill in `first_hops` with the results
+/// from [`ChannelManager::list_usable_channels`]. If it is filled in, the view of our local
+/// channels from [`NetworkGraph`] will be ignored, and only those in `first_hops` will be used.
+///
+/// The fees on channels from us to the next hop are ignored as they are assumed to all be equal.
+/// However, the enabled/disabled bit on such channels as well as the `htlc_minimum_msat` /
+/// `htlc_maximum_msat` *are* checked as they may change based on the receiving node.
 ///
-/// If some channels aren't announced, it may be useful to fill in a first_hops with the
-/// results from a local ChannelManager::list_usable_channels() call. If it is filled in, our
-/// view of our local channels (from net_graph_msg_handler) will be ignored, and only those
-/// in first_hops will be used.
+/// # Note
 ///
-/// Panics if first_hops contains channels without short_channel_ids
-/// (ChannelManager::list_usable_channels will never include such channels).
+/// May be used to re-compute a [`Route`] when handling a [`Event::PaymentPathFailed`]. Any
+/// adjustments to the [`NetworkGraph`] and channel scores should be made prior to calling this
+/// function.
 ///
-/// The fees on channels from us to next-hops are ignored (as they are assumed to all be
-/// equal), however the enabled/disabled bit on such channels as well as the
-/// htlc_minimum_msat/htlc_maximum_msat *are* checked as they may change based on the receiving node.
-pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, payee: &PublicKey, payee_features: Option<InvoiceFeatures>, first_hops: Option<&[&ChannelDetails]>,
-       last_hops: &[&RouteHint], final_value_msat: u64, final_cltv: u32, logger: L) -> Result<Route, LightningError> where L::Target: Logger {
-       // TODO: Obviously *only* using total fee cost sucks. We should consider weighting by
-       // uptime/success in using a node in the past.
-       if *payee == *our_node_id {
+/// # Panics
+///
+/// Panics if first_hops contains channels without short_channel_ids;
+/// [`ChannelManager::list_usable_channels`] will never include such channels.
+///
+/// [`ChannelManager::list_usable_channels`]: crate::ln::channelmanager::ChannelManager::list_usable_channels
+/// [`Event::PaymentPathFailed`]: crate::util::events::Event::PaymentPathFailed
+pub fn find_route<L: Deref, S: Score>(
+       our_node_pubkey: &PublicKey, params: &RouteParameters, network: &NetworkGraph,
+       first_hops: Option<&[&ChannelDetails]>, logger: L, scorer: &S
+) -> Result<Route, LightningError>
+where L::Target: Logger {
+       get_route(
+               our_node_pubkey, &params.payee, network, first_hops, params.final_value_msat,
+               params.final_cltv_expiry_delta, logger, scorer
+       )
+}
+
+pub(crate) fn get_route<L: Deref, S: Score>(
+       our_node_pubkey: &PublicKey, payee: &Payee, network: &NetworkGraph,
+       first_hops: Option<&[&ChannelDetails]>, final_value_msat: u64, final_cltv_expiry_delta: u32,
+       logger: L, scorer: &S
+) -> Result<Route, LightningError>
+where L::Target: Logger {
+       let payee_node_id = NodeId::from_pubkey(&payee.pubkey);
+       let our_node_id = NodeId::from_pubkey(&our_node_pubkey);
+
+       if payee_node_id == our_node_id {
                return Err(LightningError{err: "Cannot generate a route to ourselves".to_owned(), action: ErrorAction::IgnoreError});
        }
 
@@ -354,9 +561,11 @@ 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});
        }
 
-       for last_hop in last_hops {
-               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 payee.route_hints.iter() {
+               for hop in &route.0 {
+                       if hop.src_node_id == payee.pubkey {
+                               return Err(LightningError{err: "Route hint cannot have the payee as the source.".to_owned(), action: ErrorAction::IgnoreError});
+                       }
                }
        }
 
@@ -420,6 +629,9 @@ pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, paye
        // to use as the A* heuristic beyond just the cost to get one node further than the current
        // one.
 
+       let network_graph = network.read_only();
+       let network_channels = network_graph.channels();
+       let network_nodes = network_graph.nodes();
        let dummy_directional_info = DummyDirectionalChannelInfo { // used for first_hops routes
                cltv_expiry_delta: 0,
                htlc_minimum_msat: 0,
@@ -430,56 +642,68 @@ pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, paye
                }
        };
 
-       let mut targets = BinaryHeap::new(); //TODO: Do we care about switching to eg Fibbonaci heap?
-       let mut dist = HashMap::with_capacity(network.get_nodes().len());
-
-       // During routing, if we ignore a path due to an htlc_minimum_msat limit, we set this,
-       // indicating that we may wish to try again with a higher value, potentially paying to meet an
-       // htlc_minimum with extra fees while still finding a cheaper path.
-       let mut hit_minimum_limit;
-
-       // When arranging a route, we select multiple paths so that we can make a multi-path payment.
-       // We start with a path_value of the exact amount we want, and if that generates a route we may
-       // return it immediately. Otherwise, we don't stop searching for paths until we have 3x the
-       // amount we want in total across paths, selecting the best subset at the end.
-       const ROUTE_CAPACITY_PROVISION_FACTOR: u64 = 3;
-       let recommended_value_msat = final_value_msat * ROUTE_CAPACITY_PROVISION_FACTOR as u64;
-       let mut path_value_msat = final_value_msat;
-
        // Allow MPP only if we have a features set from somewhere that indicates the payee supports
        // it. If the payee supports it they're supposed to include it in the invoice, so that should
        // work reliably.
-       let allow_mpp = if let Some(features) = &payee_features {
+       let allow_mpp = if let Some(features) = &payee.features {
                features.supports_basic_mpp()
-       } else if let Some(node) = network.get_nodes().get(&payee) {
+       } else if let Some(node) = network_nodes.get(&payee_node_id) {
                if let Some(node_info) = node.announcement_info.as_ref() {
                        node_info.features.supports_basic_mpp()
                } else { false }
        } else { false };
+       log_trace!(logger, "Searching for a route from payer {} to payee {} {} MPP", our_node_pubkey,
+               payee.pubkey, if allow_mpp { "with" } else { "without" });
 
        // Step (1).
        // Prepare the data we'll use for payee-to-payer search by
        // inserting first hops suggested by the caller as targets.
        // Our search will then attempt to reach them while traversing from the payee node.
-       let mut first_hop_targets = HashMap::with_capacity(if first_hops.is_some() { first_hops.as_ref().unwrap().len() } else { 0 });
+       let mut first_hop_targets: HashMap<_, Vec<(_, ChannelFeatures, _, NodeFeatures)>> =
+               HashMap::with_capacity(if first_hops.is_some() { first_hops.as_ref().unwrap().len() } else { 0 });
        if let Some(hops) = first_hops {
                for chan in hops {
                        let short_channel_id = chan.short_channel_id.expect("first_hops should be filled in with usable channels, not pending ones");
-                       if chan.remote_network_id == *our_node_id {
-                               return Err(LightningError{err: "First hop cannot have our_node_id as a destination.".to_owned(), action: ErrorAction::IgnoreError});
+                       if chan.counterparty.node_id == *our_node_pubkey {
+                               return Err(LightningError{err: "First hop cannot have our_node_pubkey as a destination.".to_owned(), action: ErrorAction::IgnoreError});
                        }
-                       first_hop_targets.insert(chan.remote_network_id, (short_channel_id, chan.counterparty_features.clone(), chan.outbound_capacity_msat));
+                       first_hop_targets.entry(NodeId::from_pubkey(&chan.counterparty.node_id)).or_insert(Vec::new())
+                               .push((short_channel_id, chan.counterparty.features.to_context(), chan.outbound_capacity_msat, chan.counterparty.features.to_context()));
                }
                if first_hop_targets.is_empty() {
                        return Err(LightningError{err: "Cannot route when there are no outbound routes away from us".to_owned(), action: ErrorAction::IgnoreError});
                }
        }
 
+       let empty_channel_features = ChannelFeatures::empty();
+
+       // The main heap containing all candidate next-hops sorted by their score (max(A* fee,
+       // htlc_minimum)). Ideally this would be a heap which allowed cheap score reduction instead of
+       // adding duplicate entries when we find a better path to a given node.
+       let mut targets = BinaryHeap::new();
+
+       // Map from node_id to information about the best current path to that node, including feerate
+       // information.
+       let mut dist = HashMap::with_capacity(network_nodes.len());
+
+       // During routing, if we ignore a path due to an htlc_minimum_msat limit, we set this,
+       // indicating that we may wish to try again with a higher value, potentially paying to meet an
+       // htlc_minimum with extra fees while still finding a cheaper path.
+       let mut hit_minimum_limit;
+
+       // When arranging a route, we select multiple paths so that we can make a multi-path payment.
+       // We start with a path_value of the exact amount we want, and if that generates a route we may
+       // return it immediately. Otherwise, we don't stop searching for paths until we have 3x the
+       // amount we want in total across paths, selecting the best subset at the end.
+       const ROUTE_CAPACITY_PROVISION_FACTOR: u64 = 3;
+       let recommended_value_msat = final_value_msat * ROUTE_CAPACITY_PROVISION_FACTOR as u64;
+       let mut path_value_msat = final_value_msat;
+
        // We don't want multiple paths (as per MPP) share liquidity of the same channels.
        // This map allows paths to be aware of the channel use by other paths in the same call.
        // This would help to make a better path finding decisions and not "overbook" channels.
        // It is unaware of the directions (except for `outbound_capacity_msat` in `first_hops`).
-       let mut bookkeeped_channels_liquidity_available_msat = HashMap::new();
+       let mut bookkeeped_channels_liquidity_available_msat = HashMap::with_capacity(network_nodes.len());
 
        // Keeping track of how much value we already collected across other paths. Helps to decide:
        // - how much a new path should be transferring (upper bound);
@@ -488,14 +712,19 @@ pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, paye
        // - when we want to stop looking for new paths.
        let mut already_collected_value_msat = 0;
 
+       log_trace!(logger, "Building path from {} (payee) to {} (us/payer) for value {} msat.", payee.pubkey, our_node_pubkey, final_value_msat);
+
        macro_rules! add_entry {
                // Adds entry which goes from $src_node_id to $dest_node_id
                // over the channel with id $chan_id with fees described in
                // $directional_info.
                // $next_hops_fee_msat represents the fees paid for using all the channel *after* this one,
                // since that value has to be transferred over this channel.
+               // Returns whether this channel caused an update to `targets`.
                ( $chan_id: expr, $src_node_id: expr, $dest_node_id: expr, $directional_info: expr, $capacity_sats: expr, $chan_features: expr, $next_hops_fee_msat: expr,
-                  $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr ) => {
+                  $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr, $next_hops_path_penalty_msat: expr ) => { {
+                       // We "return" whether we updated the path at the end, via this:
+                       let mut did_add_update_path_to_src_node = false;
                        // Channels to self should not be used. This is more of belt-and-suspenders, because in
                        // practice these cases should be caught earlier:
                        // - for regular channels at channel announcement (TODO)
@@ -578,12 +807,11 @@ pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, paye
                                                // might violate htlc_minimum_msat on the hops which are next along the
                                                // payment path (upstream to the payee). To avoid that, we recompute path
                                                // path fees knowing the final path contribution after constructing it.
-                                               let path_htlc_minimum_msat = match compute_fees($next_hops_path_htlc_minimum_msat, $directional_info.fees)
-                                                               .map(|fee_msat| fee_msat.checked_add($next_hops_path_htlc_minimum_msat)) {
-                                                       Some(Some(value_msat)) => cmp::max(value_msat, $directional_info.htlc_minimum_msat),
-                                                       _ => u64::max_value()
-                                               };
-                                               let hm_entry = dist.entry(&$src_node_id);
+                                               let path_htlc_minimum_msat = compute_fees($next_hops_path_htlc_minimum_msat, $directional_info.fees)
+                                                       .and_then(|fee_msat| fee_msat.checked_add($next_hops_path_htlc_minimum_msat))
+                                                       .map(|fee_msat| cmp::max(fee_msat, $directional_info.htlc_minimum_msat))
+                                                       .unwrap_or_else(|| u64::max_value());
+                                               let hm_entry = dist.entry($src_node_id);
                                                let old_entry = hm_entry.or_insert_with(|| {
                                                        // If there was previously no known way to access
                                                        // the source node (recall it goes payee-to-payer) of $chan_id, first add
@@ -592,19 +820,16 @@ pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, paye
                                                        // as a way to reach the $dest_node_id.
                                                        let mut fee_base_msat = u32::max_value();
                                                        let mut fee_proportional_millionths = u32::max_value();
-                                                       if let Some(Some(fees)) = network.get_nodes().get(&$src_node_id).map(|node| node.lowest_inbound_channel_fees) {
+                                                       if let Some(Some(fees)) = network_nodes.get(&$src_node_id).map(|node| node.lowest_inbound_channel_fees) {
                                                                fee_base_msat = fees.base_msat;
                                                                fee_proportional_millionths = fees.proportional_millionths;
                                                        }
                                                        PathBuildingHop {
-                                                               route_hop: RouteHop {
-                                                                       pubkey: $dest_node_id.clone(),
-                                                                       node_features: NodeFeatures::empty(),
-                                                                       short_channel_id: 0,
-                                                                       channel_features: $chan_features.clone(),
-                                                                       fee_msat: 0,
-                                                                       cltv_expiry_delta: 0,
-                                                               },
+                                                               node_id: $dest_node_id.clone(),
+                                                               short_channel_id: 0,
+                                                               channel_features: $chan_features,
+                                                               fee_msat: 0,
+                                                               cltv_expiry_delta: 0,
                                                                src_lowest_inbound_fees: RoutingFees {
                                                                        base_msat: fee_base_msat,
                                                                        proportional_millionths: fee_proportional_millionths,
@@ -615,132 +840,203 @@ pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, paye
                                                                total_fee_msat: u64::max_value(),
                                                                htlc_minimum_msat: $directional_info.htlc_minimum_msat,
                                                                path_htlc_minimum_msat,
+                                                               path_penalty_msat: u64::max_value(),
+                                                               was_processed: false,
+                                                               #[cfg(any(test, feature = "fuzztarget"))]
+                                                               value_contribution_msat,
                                                        }
                                                });
 
-                                               let mut hop_use_fee_msat = 0;
-                                               let mut total_fee_msat = $next_hops_fee_msat;
-
-                                               // Ignore hop_use_fee_msat for channel-from-us as we assume all channels-from-us
-                                               // will have the same effective-fee
-                                               if $src_node_id != *our_node_id {
-                                                       match compute_fees(amount_to_transfer_over_msat, $directional_info.fees) {
-                                                               // max_value means we'll always fail
-                                                               // the old_entry.total_fee_msat > total_fee_msat check
-                                                               None => total_fee_msat = u64::max_value(),
-                                                               Some(fee_msat) => {
-                                                                       hop_use_fee_msat = fee_msat;
-                                                                       total_fee_msat += hop_use_fee_msat;
-                                                                       if let Some(prev_hop_fee_msat) = compute_fees(total_fee_msat + amount_to_transfer_over_msat,
-                                                                                                                                                               old_entry.src_lowest_inbound_fees) {
-                                                                               if let Some(incremented_total_fee_msat) = total_fee_msat.checked_add(prev_hop_fee_msat) {
-                                                                                       total_fee_msat = incremented_total_fee_msat;
-                                                                               }
-                                                                               else {
-                                                                                       // max_value means we'll always fail
-                                                                                       // the old_entry.total_fee_msat > total_fee_msat check
-                                                                                       total_fee_msat = u64::max_value();
-                                                                               }
-                                                                       } else {
-                                                                               // max_value means we'll always fail
-                                                                               // the old_entry.total_fee_msat > total_fee_msat check
-                                                                               total_fee_msat = u64::max_value();
+                                               #[allow(unused_mut)] // We only use the mut in cfg(test)
+                                               let mut should_process = !old_entry.was_processed;
+                                               #[cfg(any(test, feature = "fuzztarget"))]
+                                               {
+                                                       // In test/fuzzing builds, we do extra checks to make sure the skipping
+                                                       // of already-seen nodes only happens in cases we expect (see below).
+                                                       if !should_process { should_process = true; }
+                                               }
+
+                                               if should_process {
+                                                       let mut hop_use_fee_msat = 0;
+                                                       let mut total_fee_msat = $next_hops_fee_msat;
+
+                                                       // Ignore hop_use_fee_msat for channel-from-us as we assume all channels-from-us
+                                                       // will have the same effective-fee
+                                                       if $src_node_id != our_node_id {
+                                                               match compute_fees(amount_to_transfer_over_msat, $directional_info.fees) {
+                                                                       // max_value means we'll always fail
+                                                                       // the old_entry.total_fee_msat > total_fee_msat check
+                                                                       None => total_fee_msat = u64::max_value(),
+                                                                       Some(fee_msat) => {
+                                                                               hop_use_fee_msat = fee_msat;
+                                                                               total_fee_msat += hop_use_fee_msat;
+                                                                               // When calculating the lowest inbound fees to a node, we
+                                                                               // calculate fees here not based on the actual value we think
+                                                                               // will flow over this channel, but on the minimum value that
+                                                                               // we'll accept flowing over it. The minimum accepted value
+                                                                               // is a constant through each path collection run, ensuring
+                                                                               // consistent basis. Otherwise we may later find a
+                                                                               // different path to the source node that is more expensive,
+                                                                               // but which we consider to be cheaper because we are capacity
+                                                                               // constrained and the relative fee becomes lower.
+                                                                               match compute_fees(minimal_value_contribution_msat, old_entry.src_lowest_inbound_fees)
+                                                                                               .map(|a| a.checked_add(total_fee_msat)) {
+                                                                                       Some(Some(v)) => {
+                                                                                               total_fee_msat = v;
+                                                                                       },
+                                                                                       _ => {
+                                                                                               total_fee_msat = u64::max_value();
+                                                                                       }
+                                                                               };
                                                                        }
                                                                }
                                                        }
-                                               }
 
-                                               let new_graph_node = RouteGraphNode {
-                                                       pubkey: $src_node_id,
-                                                       lowest_fee_to_peer_through_node: total_fee_msat,
-                                                       lowest_fee_to_node: $next_hops_fee_msat as u64 + hop_use_fee_msat,
-                                                       value_contribution_msat: value_contribution_msat,
-                                                       path_htlc_minimum_msat,
-                                               };
-
-                                               // Update the way of reaching $src_node_id with the given $chan_id (from $dest_node_id),
-                                               // if this way is cheaper than the already known
-                                               // (considering the cost to "reach" this channel from the route destination,
-                                               // the cost of using this channel,
-                                               // and the cost of routing to the source node of this channel).
-                                               // Also, consider that htlc_minimum_msat_difference, because we might end up
-                                               // paying it. Consider the following exploit:
-                                               // we use 2 paths to transfer 1.5 BTC. One of them is 0-fee normal 1 BTC path,
-                                               // and for the other one we picked a 1sat-fee path with htlc_minimum_msat of
-                                               // 1 BTC. Now, since the latter is more expensive, we gonna try to cut it
-                                               // by 0.5 BTC, but then match htlc_minimum_msat by paying a fee of 0.5 BTC
-                                               // to this channel.
-                                               // Ideally the scoring could be smarter (e.g. 0.5*htlc_minimum_msat here),
-                                               // but it may require additional tracking - we don't want to double-count
-                                               // the fees included in $next_hops_path_htlc_minimum_msat, but also
-                                               // can't use something that may decrease on future hops.
-                                               let old_cost = cmp::max(old_entry.total_fee_msat, old_entry.path_htlc_minimum_msat);
-                                               let new_cost = cmp::max(total_fee_msat, path_htlc_minimum_msat);
-
-                                               if new_cost < old_cost {
-                                                       targets.push(new_graph_node);
-                                                       old_entry.next_hops_fee_msat = $next_hops_fee_msat;
-                                                       old_entry.hop_use_fee_msat = hop_use_fee_msat;
-                                                       old_entry.total_fee_msat = total_fee_msat;
-                                                       old_entry.route_hop = RouteHop {
-                                                               pubkey: $dest_node_id.clone(),
-                                                               node_features: NodeFeatures::empty(),
-                                                               short_channel_id: $chan_id.clone(),
-                                                               channel_features: $chan_features.clone(),
-                                                               fee_msat: 0, // This value will be later filled with hop_use_fee_msat of the following channel
-                                                               cltv_expiry_delta: $directional_info.cltv_expiry_delta as u32,
+                                                       let path_penalty_msat = $next_hops_path_penalty_msat.checked_add(
+                                                               scorer.channel_penalty_msat($chan_id.clone(), amount_to_transfer_over_msat, Some(*available_liquidity_msat),
+                                                                       &$src_node_id, &$dest_node_id)).unwrap_or_else(|| u64::max_value());
+                                                       let new_graph_node = RouteGraphNode {
+                                                               node_id: $src_node_id,
+                                                               lowest_fee_to_peer_through_node: total_fee_msat,
+                                                               lowest_fee_to_node: $next_hops_fee_msat as u64 + hop_use_fee_msat,
+                                                               value_contribution_msat: value_contribution_msat,
+                                                               path_htlc_minimum_msat,
+                                                               path_penalty_msat,
                                                        };
-                                                       old_entry.channel_fees = $directional_info.fees;
-                                                       old_entry.htlc_minimum_msat = $directional_info.htlc_minimum_msat;
-                                                       old_entry.path_htlc_minimum_msat = path_htlc_minimum_msat;
+
+                                                       // Update the way of reaching $src_node_id with the given $chan_id (from $dest_node_id),
+                                                       // if this way is cheaper than the already known
+                                                       // (considering the cost to "reach" this channel from the route destination,
+                                                       // the cost of using this channel,
+                                                       // and the cost of routing to the source node of this channel).
+                                                       // Also, consider that htlc_minimum_msat_difference, because we might end up
+                                                       // paying it. Consider the following exploit:
+                                                       // we use 2 paths to transfer 1.5 BTC. One of them is 0-fee normal 1 BTC path,
+                                                       // and for the other one we picked a 1sat-fee path with htlc_minimum_msat of
+                                                       // 1 BTC. Now, since the latter is more expensive, we gonna try to cut it
+                                                       // by 0.5 BTC, but then match htlc_minimum_msat by paying a fee of 0.5 BTC
+                                                       // to this channel.
+                                                       // Ideally the scoring could be smarter (e.g. 0.5*htlc_minimum_msat here),
+                                                       // but it may require additional tracking - we don't want to double-count
+                                                       // the fees included in $next_hops_path_htlc_minimum_msat, but also
+                                                       // can't use something that may decrease on future hops.
+                                                       let old_cost = cmp::max(old_entry.total_fee_msat, old_entry.path_htlc_minimum_msat)
+                                                               .checked_add(old_entry.path_penalty_msat)
+                                                               .unwrap_or_else(|| u64::max_value());
+                                                       let new_cost = cmp::max(total_fee_msat, path_htlc_minimum_msat)
+                                                               .checked_add(path_penalty_msat)
+                                                               .unwrap_or_else(|| u64::max_value());
+
+                                                       if !old_entry.was_processed && new_cost < old_cost {
+                                                               targets.push(new_graph_node);
+                                                               old_entry.next_hops_fee_msat = $next_hops_fee_msat;
+                                                               old_entry.hop_use_fee_msat = hop_use_fee_msat;
+                                                               old_entry.total_fee_msat = total_fee_msat;
+                                                               old_entry.node_id = $dest_node_id.clone();
+                                                               old_entry.short_channel_id = $chan_id.clone();
+                                                               old_entry.channel_features = $chan_features;
+                                                               old_entry.fee_msat = 0; // This value will be later filled with hop_use_fee_msat of the following channel
+                                                               old_entry.cltv_expiry_delta = $directional_info.cltv_expiry_delta as u32;
+                                                               old_entry.channel_fees = $directional_info.fees;
+                                                               old_entry.htlc_minimum_msat = $directional_info.htlc_minimum_msat;
+                                                               old_entry.path_htlc_minimum_msat = path_htlc_minimum_msat;
+                                                               old_entry.path_penalty_msat = path_penalty_msat;
+                                                               #[cfg(any(test, feature = "fuzztarget"))]
+                                                               {
+                                                                       old_entry.value_contribution_msat = value_contribution_msat;
+                                                               }
+                                                               did_add_update_path_to_src_node = true;
+                                                       } else if old_entry.was_processed && new_cost < old_cost {
+                                                               #[cfg(any(test, feature = "fuzztarget"))]
+                                                               {
+                                                                       // If we're skipping processing a node which was previously
+                                                                       // processed even though we found another path to it with a
+                                                                       // cheaper fee, check that it was because the second path we
+                                                                       // found (which we are processing now) has a lower value
+                                                                       // contribution due to an HTLC minimum limit.
+                                                                       //
+                                                                       // e.g. take a graph with two paths from node 1 to node 2, one
+                                                                       // through channel A, and one through channel B. Channel A and
+                                                                       // B are both in the to-process heap, with their scores set by
+                                                                       // a higher htlc_minimum than fee.
+                                                                       // Channel A is processed first, and the channels onwards from
+                                                                       // node 1 are added to the to-process heap. Thereafter, we pop
+                                                                       // Channel B off of the heap, note that it has a much more
+                                                                       // restrictive htlc_maximum_msat, and recalculate the fees for
+                                                                       // all of node 1's channels using the new, reduced, amount.
+                                                                       //
+                                                                       // This would be bogus - we'd be selecting a higher-fee path
+                                                                       // with a lower htlc_maximum_msat instead of the one we'd
+                                                                       // already decided to use.
+                                                                       debug_assert!(path_htlc_minimum_msat < old_entry.path_htlc_minimum_msat);
+                                                                       debug_assert!(
+                                                                               value_contribution_msat + path_penalty_msat <
+                                                                               old_entry.value_contribution_msat + old_entry.path_penalty_msat
+                                                                       );
+                                                               }
+                                                       }
                                                }
                                        }
                                }
                        }
-               };
+                       did_add_update_path_to_src_node
+               } }
        }
 
+       let empty_node_features = NodeFeatures::empty();
        // Find ways (channels with destination) to reach a given node and store them
        // in the corresponding data structures (routing graph etc).
        // $fee_to_target_msat represents how much it costs to reach to this node from the payee,
        // meaning how much will be paid in fees after this node (to the best of our knowledge).
        // This data can later be helpful to optimize routing (pay lower fees).
        macro_rules! add_entries_to_cheapest_to_target_node {
-               ( $node: expr, $node_id: expr, $fee_to_target_msat: expr, $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr ) => {
-                       if first_hops.is_some() {
-                               if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat)) = first_hop_targets.get(&$node_id) {
-                                       add_entry!(first_hop, *our_node_id, $node_id, dummy_directional_info, Some(outbound_capacity_msat / 1000), features.to_context(), $fee_to_target_msat, $next_hops_value_contribution, $next_hops_path_htlc_minimum_msat);
+               ( $node: expr, $node_id: expr, $fee_to_target_msat: expr, $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr, $next_hops_path_penalty_msat: expr ) => {
+                       let skip_node = if let Some(elem) = dist.get_mut(&$node_id) {
+                               let was_processed = elem.was_processed;
+                               elem.was_processed = true;
+                               was_processed
+                       } else {
+                               // Entries are added to dist in add_entry!() when there is a channel from a node.
+                               // Because there are no channels from payee, it will not have a dist entry at this point.
+                               // If we're processing any other node, it is always be the result of a channel from it.
+                               assert_eq!($node_id, payee_node_id);
+                               false
+                       };
+
+                       if !skip_node {
+                               if let Some(first_channels) = first_hop_targets.get(&$node_id) {
+                                       for (ref first_hop, ref features, ref outbound_capacity_msat, _) in first_channels {
+                                               add_entry!(first_hop, our_node_id, $node_id, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, $fee_to_target_msat, $next_hops_value_contribution, $next_hops_path_htlc_minimum_msat, $next_hops_path_penalty_msat);
+                                       }
                                }
-                       }
 
-                       let features;
-                       if let Some(node_info) = $node.announcement_info.as_ref() {
-                               features = node_info.features.clone();
-                       } else {
-                               features = NodeFeatures::empty();
-                       }
+                               let features = if let Some(node_info) = $node.announcement_info.as_ref() {
+                                       &node_info.features
+                               } else {
+                                       &empty_node_features
+                               };
 
-                       if !features.requires_unknown_bits() {
-                               for chan_id in $node.channels.iter() {
-                                       let chan = network.get_channels().get(chan_id).unwrap();
-                                       if !chan.features.requires_unknown_bits() {
-                                               if chan.node_one == *$node_id {
-                                                       // ie $node is one, ie next hop in A* is two, via the two_to_one channel
-                                                       if first_hops.is_none() || chan.node_two != *our_node_id {
-                                                               if let Some(two_to_one) = chan.two_to_one.as_ref() {
-                                                                       if two_to_one.enabled {
-                                                                               add_entry!(chan_id, chan.node_two, chan.node_one, two_to_one, chan.capacity_sats, chan.features, $fee_to_target_msat, $next_hops_value_contribution, $next_hops_path_htlc_minimum_msat);
+                               if !features.requires_unknown_bits() {
+                                       for chan_id in $node.channels.iter() {
+                                               let chan = network_channels.get(chan_id).unwrap();
+                                               if !chan.features.requires_unknown_bits() {
+                                                       if chan.node_one == $node_id {
+                                                               // ie $node is one, ie next hop in A* is two, via the two_to_one channel
+                                                               if first_hops.is_none() || chan.node_two != our_node_id {
+                                                                       if let Some(two_to_one) = chan.two_to_one.as_ref() {
+                                                                               if two_to_one.enabled {
+                                                                                       add_entry!(chan_id, chan.node_two, chan.node_one, two_to_one, chan.capacity_sats, &chan.features, $fee_to_target_msat, $next_hops_value_contribution, $next_hops_path_htlc_minimum_msat, $next_hops_path_penalty_msat);
+                                                                               }
                                                                        }
                                                                }
-                                                       }
-                                               } else {
-                                                       if first_hops.is_none() || chan.node_one != *our_node_id {
-                                                               if let Some(one_to_two) = chan.one_to_two.as_ref() {
-                                                                       if one_to_two.enabled {
-                                                                               add_entry!(chan_id, chan.node_one, chan.node_two, one_to_two, chan.capacity_sats, chan.features, $fee_to_target_msat, $next_hops_value_contribution, $next_hops_path_htlc_minimum_msat);
+                                                       } else {
+                                                               if first_hops.is_none() || chan.node_one != our_node_id{
+                                                                       if let Some(one_to_two) = chan.one_to_two.as_ref() {
+                                                                               if one_to_two.enabled {
+                                                                                       add_entry!(chan_id, chan.node_one, chan.node_two, one_to_two, chan.capacity_sats, &chan.features, $fee_to_target_msat, $next_hops_value_contribution, $next_hops_path_htlc_minimum_msat, $next_hops_path_penalty_msat);
+                                                                               }
                                                                        }
                                                                }
-
                                                        }
                                                }
                                        }
@@ -762,69 +1058,141 @@ pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, paye
 
                // If first hop is a private channel and the only way to reach the payee, this is the only
                // place where it could be added.
-               if first_hops.is_some() {
-                       if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat)) = first_hop_targets.get(&payee) {
-                               add_entry!(first_hop, *our_node_id, payee, dummy_directional_info, Some(outbound_capacity_msat / 1000), features.to_context(), 0, path_value_msat, 0);
+               if let Some(first_channels) = first_hop_targets.get(&payee_node_id) {
+                       for (ref first_hop, ref features, ref outbound_capacity_msat, _) in first_channels {
+                               let added = add_entry!(first_hop, our_node_id, payee_node_id, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, 0, path_value_msat, 0, 0u64);
+                               log_trace!(logger, "{} direct route to payee via SCID {}", if added { "Added" } else { "Skipped" }, first_hop);
                        }
                }
 
                // Add the payee as a target, so that the payee-to-payer
                // search algorithm knows what to start with.
-               match network.get_nodes().get(payee) {
+               match network_nodes.get(&payee_node_id) {
                        // The payee is not in our network graph, so nothing to add here.
                        // There is still a chance of reaching them via last_hops though,
                        // so don't yet fail the payment here.
                        // If not, targets.pop() will not even let us enter the loop in step 2.
                        None => {},
                        Some(node) => {
-                               add_entries_to_cheapest_to_target_node!(node, payee, 0, path_value_msat, 0);
+                               add_entries_to_cheapest_to_target_node!(node, payee_node_id, 0, path_value_msat, 0, 0u64);
                        },
                }
 
-               // Step (1).
+               // Step (2).
                // 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 payee.route_hints.iter().filter(|route| !route.0.is_empty()) {
+                       let first_hop_in_route = &(route.0)[0];
                        let have_hop_src_in_graph =
-                               if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat)) = first_hop_targets.get(&hop.src_node_id) {
-                                       // If this hop connects to a node with which we have a direct channel, ignore
-                                       // the network graph and add both the hop and our direct channel to
-                                       // the candidate set.
-                                       //
-                                       // Currently there are no channel-context features defined, so we are a
-                                       // bit lazy here. In the future, we should pull them out via our
-                                       // ChannelManager, but there's no reason to waste the space until we
-                                       // need them.
-                                       add_entry!(first_hop, *our_node_id , hop.src_node_id, dummy_directional_info, Some(outbound_capacity_msat / 1000), features.to_context(), 0, path_value_msat, 0);
-                                       true
-                               } else {
-                                       // In any other case, only add the hop if the source is in the regular network
-                                       // graph:
-                                       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(&NodeId::from_pubkey(&first_hop_in_route.src_node_id)).is_some() ||
+                               network_nodes.get(&NodeId::from_pubkey(&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,
-                               };
-                               add_entry!(hop.short_channel_id, hop.src_node_id, payee, directional_info, None::<u64>, ChannelFeatures::empty(), 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.pubkey).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;
+                               let mut aggregate_next_hops_path_penalty_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,
+                                       };
+
+                                       // We want a value of final_value_msat * ROUTE_CAPACITY_PROVISION_FACTOR but we
+                                       // need it to increment at each hop by the fee charged at later hops. Further,
+                                       // we need to ensure we round up when we divide to get satoshis.
+                                       let channel_cap_msat = final_value_msat
+                                               .checked_mul(ROUTE_CAPACITY_PROVISION_FACTOR).and_then(|v| v.checked_add(aggregate_next_hops_fee_msat))
+                                               .unwrap_or(u64::max_value());
+                                       let channel_cap_sat = match channel_cap_msat.checked_add(999) {
+                                               None => break, // We overflowed above, just ignore this route hint
+                                               Some(val) => Some(val / 1000),
+                                       };
+
+                                       let src_node_id = NodeId::from_pubkey(&hop.src_node_id);
+                                       let dest_node_id = NodeId::from_pubkey(&prev_hop_id);
+                                       aggregate_next_hops_path_penalty_msat = aggregate_next_hops_path_penalty_msat
+                                               .checked_add(scorer.channel_penalty_msat(hop.short_channel_id, final_value_msat, None, &src_node_id, &dest_node_id))
+                                               .unwrap_or_else(|| u64::max_value());
+
+                                       // 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, src_node_id, dest_node_id, directional_info, channel_cap_sat, &empty_channel_features, aggregate_next_hops_fee_msat, path_value_msat, aggregate_next_hops_path_htlc_minimum_msat, aggregate_next_hops_path_penalty_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(first_channels) = first_hop_targets.get(&NodeId::from_pubkey(&prev_hop_id)) {
+                                               for (ref first_hop, ref features, ref outbound_capacity_msat, _) in first_channels {
+                                                       add_entry!(first_hop, our_node_id , NodeId::from_pubkey(&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, aggregate_next_hops_path_penalty_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(first_channels) = first_hop_targets.get(&NodeId::from_pubkey(&hop.src_node_id)) {
+                                                       for (ref first_hop, ref features, ref outbound_capacity_msat, _) in first_channels {
+                                                               add_entry!(first_hop, our_node_id , NodeId::from_pubkey(&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, aggregate_next_hops_path_penalty_msat);
+                                                       }
+                                               }
+                                       }
+                               }
                        }
                }
 
+               log_trace!(logger, "Starting main path collection loop with {} nodes pre-filled from first/last hops.", targets.len());
+
                // At this point, targets are filled with the data from first and
                // last hops communicated by the caller, and the payment receiver.
                let mut found_new_path = false;
 
-               // Step (2).
+               // Step (3).
                // If this loop terminates due the exhaustion of targets, two situations are possible:
                // - not enough outgoing liquidity:
                //   0 < already_collected_value_msat < final_value_msat
@@ -833,40 +1201,50 @@ pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, paye
                // Both these cases (and other cases except reaching recommended_value_msat) mean that
                // paths_collection will be stopped because found_new_path==false.
                // This is not necessarily a routing failure.
-               'path_construction: while let Some(RouteGraphNode { pubkey, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat, .. }) = targets.pop() {
+               'path_construction: while let Some(RouteGraphNode { node_id, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat, path_penalty_msat, .. }) = targets.pop() {
 
                        // Since we're going payee-to-payer, hitting our node as a target means we should stop
                        // traversing the graph and arrange the path out of what we found.
-                       if pubkey == *our_node_id {
+                       if node_id == our_node_id {
                                let mut new_entry = dist.remove(&our_node_id).unwrap();
-                               let mut ordered_hops = vec!(new_entry.clone());
+                               let mut ordered_hops = vec!((new_entry.clone(), NodeFeatures::empty()));
 
                                'path_walk: loop {
-                                       if let Some(&(_, ref features, _)) = first_hop_targets.get(&ordered_hops.last().unwrap().route_hop.pubkey) {
-                                               ordered_hops.last_mut().unwrap().route_hop.node_features = features.to_context();
-                                       } else if let Some(node) = network.get_nodes().get(&ordered_hops.last().unwrap().route_hop.pubkey) {
-                                               if let Some(node_info) = node.announcement_info.as_ref() {
-                                                       ordered_hops.last_mut().unwrap().route_hop.node_features = node_info.features.clone();
+                                       let mut features_set = false;
+                                       if let Some(first_channels) = first_hop_targets.get(&ordered_hops.last().unwrap().0.node_id) {
+                                               for (scid, _, _, ref features) in first_channels {
+                                                       if *scid == ordered_hops.last().unwrap().0.short_channel_id {
+                                                               ordered_hops.last_mut().unwrap().1 = features.clone();
+                                                               features_set = true;
+                                                               break;
+                                                       }
+                                               }
+                                       }
+                                       if !features_set {
+                                               if let Some(node) = network_nodes.get(&ordered_hops.last().unwrap().0.node_id) {
+                                                       if let Some(node_info) = node.announcement_info.as_ref() {
+                                                               ordered_hops.last_mut().unwrap().1 = node_info.features.clone();
+                                                       } else {
+                                                               ordered_hops.last_mut().unwrap().1 = NodeFeatures::empty();
+                                                       }
                                                } else {
-                                                       ordered_hops.last_mut().unwrap().route_hop.node_features = NodeFeatures::empty();
+                                                       // We should be able to fill in features for everything except the last
+                                                       // hop, if the last hop was provided via a BOLT 11 invoice (though we
+                                                       // should be able to extend it further as BOLT 11 does have feature
+                                                       // flags for the last hop node itself).
+                                                       assert!(ordered_hops.last().unwrap().0.node_id == payee_node_id);
                                                }
-                                       } else {
-                                               // We should be able to fill in features for everything except the last
-                                               // hop, if the last hop was provided via a BOLT 11 invoice (though we
-                                               // should be able to extend it further as BOLT 11 does have feature
-                                               // flags for the last hop node itself).
-                                               assert!(ordered_hops.last().unwrap().route_hop.pubkey == *payee);
                                        }
 
                                        // Means we succesfully traversed from the payer to the payee, now
                                        // save this path for the payment route. Also, update the liquidity
                                        // remaining on the used hops, so that we take them into account
                                        // while looking for more paths.
-                                       if ordered_hops.last().unwrap().route_hop.pubkey == *payee {
+                                       if ordered_hops.last().unwrap().0.node_id == payee_node_id {
                                                break 'path_walk;
                                        }
 
-                                       new_entry = match dist.remove(&ordered_hops.last().unwrap().route_hop.pubkey) {
+                                       new_entry = match dist.remove(&ordered_hops.last().unwrap().0.node_id) {
                                                Some(payment_hop) => payment_hop,
                                                // We can't arrive at None because, if we ever add an entry to targets,
                                                // we also fill in the entry in dist (see add_entry!).
@@ -875,13 +1253,16 @@ pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, paye
                                        // We "propagate" the fees one hop backward (topologically) here,
                                        // so that fees paid for a HTLC forwarding on the current channel are
                                        // associated with the previous channel (where they will be subtracted).
-                                       ordered_hops.last_mut().unwrap().route_hop.fee_msat = new_entry.hop_use_fee_msat;
-                                       ordered_hops.last_mut().unwrap().route_hop.cltv_expiry_delta = new_entry.route_hop.cltv_expiry_delta;
-                                       ordered_hops.push(new_entry.clone());
+                                       ordered_hops.last_mut().unwrap().0.fee_msat = new_entry.hop_use_fee_msat;
+                                       ordered_hops.last_mut().unwrap().0.cltv_expiry_delta = new_entry.cltv_expiry_delta;
+                                       ordered_hops.push((new_entry.clone(), NodeFeatures::empty()));
                                }
-                               ordered_hops.last_mut().unwrap().route_hop.fee_msat = value_contribution_msat;
-                               ordered_hops.last_mut().unwrap().hop_use_fee_msat = 0;
-                               ordered_hops.last_mut().unwrap().route_hop.cltv_expiry_delta = final_cltv;
+                               ordered_hops.last_mut().unwrap().0.fee_msat = value_contribution_msat;
+                               ordered_hops.last_mut().unwrap().0.hop_use_fee_msat = 0;
+                               ordered_hops.last_mut().unwrap().0.cltv_expiry_delta = final_cltv_expiry_delta;
+
+                               log_trace!(logger, "Found a path back to us from the target with {} hops contributing up to {} msat: {:?}",
+                                       ordered_hops.len(), value_contribution_msat, ordered_hops);
 
                                let mut payment_path = PaymentPath {hops: ordered_hops};
 
@@ -902,16 +1283,11 @@ pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, paye
                                // Remember that we used these channels so that we don't rely
                                // on the same liquidity in future paths.
                                let mut prevented_redundant_path_selection = false;
-                               for payment_hop in payment_path.hops.iter() {
-                                       let channel_liquidity_available_msat = bookkeeped_channels_liquidity_available_msat.get_mut(&payment_hop.route_hop.short_channel_id).unwrap();
+                               for (payment_hop, _) in payment_path.hops.iter() {
+                                       let channel_liquidity_available_msat = bookkeeped_channels_liquidity_available_msat.get_mut(&payment_hop.short_channel_id).unwrap();
                                        let mut spent_on_hop_msat = value_contribution_msat;
                                        let next_hops_fee_msat = payment_hop.next_hops_fee_msat;
                                        spent_on_hop_msat += next_hops_fee_msat;
-                                       if *channel_liquidity_available_msat < spent_on_hop_msat {
-                                               // This should not happen because we do recompute fees right before,
-                                               // trying to avoid cases when a hop is not usable due to the fee situation.
-                                               break 'path_construction;
-                                       }
                                        if spent_on_hop_msat == *channel_liquidity_available_msat {
                                                // If this path used all of this channel's available liquidity, we know
                                                // this path will not be selected again in the next loop iteration.
@@ -923,8 +1299,9 @@ pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, paye
                                        // If we weren't capped by hitting a liquidity limit on a channel in the path,
                                        // we'll probably end up picking the same path again on the next iteration.
                                        // Decrease the available liquidity of a hop in the middle of the path.
-                                       let victim_liquidity = bookkeeped_channels_liquidity_available_msat.get_mut(
-                                               &payment_path.hops[(payment_path.hops.len() - 1) / 2].route_hop.short_channel_id).unwrap();
+                                       let victim_scid = payment_path.hops[(payment_path.hops.len() - 1) / 2].0.short_channel_id;
+                                       log_trace!(logger, "Disabling channel {} for future path building iterations to avoid duplicates.", victim_scid);
+                                       let victim_liquidity = bookkeeped_channels_liquidity_available_msat.get_mut(&victim_scid).unwrap();
                                        *victim_liquidity = 0;
                                }
 
@@ -939,13 +1316,18 @@ pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, paye
                                break 'path_construction;
                        }
 
+                       // If we found a path back to the payee, we shouldn't try to process it again. This is
+                       // the equivalent of the `elem.was_processed` check in
+                       // add_entries_to_cheapest_to_target_node!() (see comment there for more info).
+                       if node_id == payee_node_id { continue 'path_construction; }
+
                        // Otherwise, since the current target node is not us,
                        // keep "unrolling" the payment graph from payee to payer by
                        // finding a way to reach the current target from the payer side.
-                       match network.get_nodes().get(&pubkey) {
+                       match network_nodes.get(&node_id) {
                                None => {},
                                Some(node) => {
-                                       add_entries_to_cheapest_to_target_node!(node, &pubkey, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat);
+                                       add_entries_to_cheapest_to_target_node!(node, node_id, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat, path_penalty_msat);
                                },
                        }
                }
@@ -955,12 +1337,14 @@ pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, paye
                        break 'paths_collection;
                }
 
-               // Step (3).
+               // Step (4).
                // Stop either when the recommended value is reached or if no new path was found in this
                // iteration.
                // In the latter case, making another path finding attempt won't help,
                // because we deterministically terminated the search due to low liquidity.
                if already_collected_value_msat >= recommended_value_msat || !found_new_path {
+                       log_trace!(logger, "Have now collected {} msat (seeking {} msat) in paths. Last path loop {} a new path.",
+                               already_collected_value_msat, recommended_value_msat, if found_new_path { "found" } else { "did not find" });
                        break 'paths_collection;
                } else if found_new_path && already_collected_value_msat == final_value_msat && payment_paths.len() == 1 {
                        // Further, if this was our first walk of the graph, and we weren't limited by an
@@ -969,13 +1353,15 @@ pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, paye
                        // potentially allowing us to pay fees to meet the htlc_minimum on the new path while
                        // still keeping a lower total fee than this path.
                        if !hit_minimum_limit {
+                               log_trace!(logger, "Collected exactly our payment amount on the first pass, without hitting an htlc_minimum_msat limit, exiting.");
                                break 'paths_collection;
                        }
+                       log_trace!(logger, "Collected our payment amount on the first pass, but running again to collect extra paths with a potentially higher limit.");
                        path_value_msat = recommended_value_msat;
                }
        }
 
-       // Step (4).
+       // Step (5).
        if payment_paths.len() == 0 {
                return Err(LightningError{err: "Failed to find a path to the given destination".to_owned(), action: ErrorAction::IgnoreError});
        }
@@ -996,12 +1382,12 @@ pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, paye
                let mut cur_route = Vec::<PaymentPath>::new();
                let mut aggregate_route_value_msat = 0;
 
-               // Step (5).
+               // Step (6).
                // TODO: real random shuffle
                // Currently just starts with i_th and goes up to i-1_th in a looped way.
                let cur_payment_paths = [&payment_paths[i..], &payment_paths[..i]].concat();
 
-               // Step (6).
+               // Step (7).
                for payment_path in cur_payment_paths {
                        cur_route.push(payment_path.clone());
                        aggregate_route_value_msat += payment_path.get_value_msat();
@@ -1040,11 +1426,11 @@ pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, paye
 
                                assert!(cur_route.len() > 0);
 
-                               // Step (7).
+                               // Step (8).
                                // Now, substract the overpaid value from the most-expensive path.
                                // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
                                // so that the sender pays less fees overall. And also htlc_minimum_msat.
-                               cur_route.sort_by_key(|path| { path.hops.iter().map(|hop| hop.channel_fees.proportional_millionths as u64).sum::<u64>() });
+                               cur_route.sort_by_key(|path| { path.hops.iter().map(|hop| hop.0.channel_fees.proportional_millionths as u64).sum::<u64>() });
                                let expensive_payment_path = cur_route.first_mut().unwrap();
                                // We already dropped all the small channels above, meaning all the
                                // remaining channels are larger than remaining overpaid_value_msat.
@@ -1057,35 +1443,53 @@ pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, paye
                drawn_routes.push(cur_route);
        }
 
-       // Step (8).
+       // Step (9).
        // Select the best route by lowest total fee.
        drawn_routes.sort_by_key(|paths| paths.iter().map(|path| path.get_total_fee_paid_msat()).sum::<u64>());
-       let mut selected_paths = Vec::<Vec<RouteHop>>::new();
+       let mut selected_paths = Vec::<Vec<Result<RouteHop, LightningError>>>::new();
        for payment_path in drawn_routes.first().unwrap() {
-               selected_paths.push(payment_path.hops.iter().map(|payment_hop| payment_hop.route_hop.clone()).collect());
+               selected_paths.push(payment_path.hops.iter().map(|(payment_hop, node_features)| {
+                       Ok(RouteHop {
+                               pubkey: PublicKey::from_slice(payment_hop.node_id.as_slice()).map_err(|_| LightningError{err: format!("Public key {:?} is invalid", &payment_hop.node_id), action: ErrorAction::IgnoreAndLog(Level::Trace)})?,
+                               node_features: node_features.clone(),
+                               short_channel_id: payment_hop.short_channel_id,
+                               channel_features: payment_hop.channel_features.clone(),
+                               fee_msat: payment_hop.fee_msat,
+                               cltv_expiry_delta: payment_hop.cltv_expiry_delta,
+                       })
+               }).collect());
        }
 
-       if let Some(features) = &payee_features {
+       if let Some(features) = &payee.features {
                for path in selected_paths.iter_mut() {
-                       path.last_mut().unwrap().node_features = features.to_context();
+                       if let Ok(route_hop) = path.last_mut().unwrap() {
+                               route_hop.node_features = features.to_context();
+                       }
                }
        }
 
-       let route = Route { paths: selected_paths };
-       log_trace!(logger, "Got route: {}", log_route!(route));
+       let route = Route {
+               paths: selected_paths.into_iter().map(|path| path.into_iter().collect()).collect::<Result<Vec<_>, _>>()?,
+               payee: Some(payee.clone()),
+       };
+       log_info!(logger, "Got route to {}: {}", payee.pubkey, log_route!(route));
        Ok(route)
 }
 
 #[cfg(test)]
 mod tests {
-       use routing::router::{get_route, RouteHint, RoutingFees};
-       use routing::network_graph::{NetworkGraph, NetGraphMsgHandler};
+       use routing::scoring::Score;
+       use routing::network_graph::{NetworkGraph, NetGraphMsgHandler, NodeId};
+       use routing::router::{get_route, Payee, Route, RouteHint, RouteHintHop, RouteHop, RoutingFees};
+       use chain::transaction::OutPoint;
        use ln::features::{ChannelFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
        use ln::msgs::{ErrorAction, LightningError, OptionalField, UnsignedChannelAnnouncement, ChannelAnnouncement, RoutingMessageHandler,
           NodeAnnouncement, UnsignedNodeAnnouncement, ChannelUpdate, UnsignedChannelUpdate};
        use ln::channelmanager;
        use util::test_utils;
        use util::ser::Writeable;
+       #[cfg(c_bindings)]
+       use util::ser::Writer;
 
        use bitcoin::hashes::sha256d::Hash as Sha256dHash;
        use bitcoin::hashes::Hash;
@@ -1100,11 +1504,39 @@ mod tests {
        use bitcoin::secp256k1::key::{PublicKey,SecretKey};
        use bitcoin::secp256k1::{Secp256k1, All};
 
-       use std::sync::Arc;
+       use prelude::*;
+       use sync::{self, Arc};
+
+       fn get_channel_details(short_channel_id: Option<u64>, node_id: PublicKey,
+                       features: InitFeatures, outbound_capacity_msat: u64) -> channelmanager::ChannelDetails {
+               channelmanager::ChannelDetails {
+                       channel_id: [0; 32],
+                       counterparty: channelmanager::ChannelCounterparty {
+                               features,
+                               node_id,
+                               unspendable_punishment_reserve: 0,
+                               forwarding_info: None,
+                       },
+                       funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
+                       short_channel_id,
+                       channel_value_satoshis: 0,
+                       user_channel_id: 0,
+                       balance_msat: 0,
+                       outbound_capacity_msat,
+                       inbound_capacity_msat: 42,
+                       unspendable_punishment_reserve: None,
+                       confirmations_required: None,
+                       force_close_spend_delay: None,
+                       is_outbound: true, is_funding_locked: true,
+                       is_usable: true, is_public: true,
+               }
+       }
 
        // Using the same keys for LN and BTC ids
-       fn add_channel(net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>, secp_ctx: &Secp256k1<All>, node_1_privkey: &SecretKey,
-          node_2_privkey: &SecretKey, features: ChannelFeatures, short_channel_id: u64) {
+       fn add_channel(
+               net_graph_msg_handler: &NetGraphMsgHandler<Arc<NetworkGraph>, Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>,
+               secp_ctx: &Secp256k1<All>, node_1_privkey: &SecretKey, node_2_privkey: &SecretKey, features: ChannelFeatures, short_channel_id: u64
+       ) {
                let node_id_1 = PublicKey::from_secret_key(&secp_ctx, node_1_privkey);
                let node_id_2 = PublicKey::from_secret_key(&secp_ctx, node_2_privkey);
 
@@ -1133,7 +1565,10 @@ mod tests {
                };
        }
 
-       fn update_channel(net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>, secp_ctx: &Secp256k1<All>, node_privkey: &SecretKey, update: UnsignedChannelUpdate) {
+       fn update_channel(
+               net_graph_msg_handler: &NetGraphMsgHandler<Arc<NetworkGraph>, Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>,
+               secp_ctx: &Secp256k1<All>, node_privkey: &SecretKey, update: UnsignedChannelUpdate
+       ) {
                let msghash = hash_to_message!(&Sha256dHash::hash(&update.encode()[..])[..]);
                let valid_channel_update = ChannelUpdate {
                        signature: secp_ctx.sign(&msghash, node_privkey),
@@ -1146,8 +1581,10 @@ mod tests {
                };
        }
 
-       fn add_or_update_node(net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>, secp_ctx: &Secp256k1<All>, node_privkey: &SecretKey,
-          features: NodeFeatures, timestamp: u32) {
+       fn add_or_update_node(
+               net_graph_msg_handler: &NetGraphMsgHandler<Arc<NetworkGraph>, Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>,
+               secp_ctx: &Secp256k1<All>, node_privkey: &SecretKey, features: NodeFeatures, timestamp: u32
+       ) {
                let node_id = PublicKey::from_secret_key(&secp_ctx, node_privkey);
                let unsigned_announcement = UnsignedNodeAnnouncement {
                        features,
@@ -1199,12 +1636,19 @@ mod tests {
                }
        }
 
-       fn build_graph() -> (Secp256k1<All>, NetGraphMsgHandler<std::sync::Arc<test_utils::TestChainSource>, std::sync::Arc<crate::util::test_utils::TestLogger>>, std::sync::Arc<test_utils::TestChainSource>, std::sync::Arc<test_utils::TestLogger>) {
+       fn build_graph() -> (
+               Secp256k1<All>,
+               sync::Arc<NetworkGraph>,
+               NetGraphMsgHandler<sync::Arc<NetworkGraph>, sync::Arc<test_utils::TestChainSource>, sync::Arc<crate::util::test_utils::TestLogger>>,
+               sync::Arc<test_utils::TestChainSource>,
+               sync::Arc<test_utils::TestLogger>,
+       ) {
                let secp_ctx = Secp256k1::new();
                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:
+               let network_graph = Arc::new(NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash()));
+               let net_graph_msg_handler = NetGraphMsgHandler::new(Arc::clone(&network_graph), None, Arc::clone(&logger));
+               // Build network from our_id to node6:
                //
                //        -1(1)2-  node0  -1(3)2-
                //       /                       \
@@ -1240,6 +1684,8 @@ 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
                //
@@ -1499,21 +1945,23 @@ mod tests {
 
                add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[5], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
 
-               (secp_ctx, net_graph_msg_handler, chain_monitor, logger)
+               (secp_ctx, network_graph, net_graph_msg_handler, chain_monitor, logger)
        }
 
        #[test]
        fn simple_route_test() {
-               let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
+               let (secp_ctx, network_graph, _, _, logger) = build_graph();
                let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
+               let payee = Payee::from_node_id(nodes[2]);
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
 
                // Simple route to 2 via 1
 
-               if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 0, 42, Arc::clone(&logger)) {
+               if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &payee, &network_graph, None, 0, 42, Arc::clone(&logger), &scorer) {
                        assert_eq!(err, "Cannot send a payment of 0 msat");
                } else { panic!(); }
 
-               let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
+               let route = get_route(&our_id, &payee, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
                assert_eq!(route.paths[0].len(), 2);
 
                assert_eq!(route.paths[0][0].pubkey, nodes[1]);
@@ -1533,36 +1981,29 @@ mod tests {
 
        #[test]
        fn invalid_first_hop_test() {
-               let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
+               let (secp_ctx, network_graph, _, _, logger) = build_graph();
                let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
+               let payee = Payee::from_node_id(nodes[2]);
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
 
                // Simple route to 2 via 1
 
-               let our_chans = vec![channelmanager::ChannelDetails {
-                       channel_id: [0; 32],
-                       short_channel_id: Some(2),
-                       remote_network_id: our_id,
-                       counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
-                       channel_value_satoshis: 100000,
-                       user_id: 0,
-                       outbound_capacity_msat: 100000,
-                       inbound_capacity_msat: 100000,
-                       is_live: true,
-                       counterparty_forwarding_info: None,
-               }];
-
-               if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger)) {
-                       assert_eq!(err, "First hop cannot have our_node_id as a destination.");
+               let our_chans = vec![get_channel_details(Some(2), our_id, InitFeatures::from_le_bytes(vec![0b11]), 100000)];
+
+               if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &payee, &network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 100, 42, Arc::clone(&logger), &scorer) {
+                       assert_eq!(err, "First hop cannot have our_node_pubkey as a destination.");
                } else { panic!(); }
 
-               let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
+               let route = get_route(&our_id, &payee, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
                assert_eq!(route.paths[0].len(), 2);
        }
 
        #[test]
        fn htlc_minimum_test() {
-               let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
+               let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
                let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
+               let payee = Payee::from_node_id(nodes[2]);
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
 
                // Simple route to 2 via 1
 
@@ -1659,7 +2100,7 @@ mod tests {
                });
 
                // Not possible to send 199_999_999, because the minimum on channel=2 is 200_000_000.
-               if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 199_999_999, 42, Arc::clone(&logger)) {
+               if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &payee, &network_graph, None, 199_999_999, 42, Arc::clone(&logger), &scorer) {
                        assert_eq!(err, "Failed to find a path to the given destination");
                } else { panic!(); }
 
@@ -1678,14 +2119,16 @@ mod tests {
                });
 
                // A payment above the minimum should pass
-               let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 199_999_999, 42, Arc::clone(&logger)).unwrap();
+               let route = get_route(&our_id, &payee, &network_graph, None, 199_999_999, 42, Arc::clone(&logger), &scorer).unwrap();
                assert_eq!(route.paths[0].len(), 2);
        }
 
        #[test]
        fn htlc_minimum_overpay_test() {
-               let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
+               let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
                let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
+               let payee = Payee::from_node_id(nodes[2]).with_features(InvoiceFeatures::known());
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
 
                // A route to node#2 via two paths.
                // One path allows transferring 35-40 sats, another one also allows 35-40 sats.
@@ -1755,8 +2198,7 @@ mod tests {
                        excess_data: Vec::new()
                });
 
-               let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
-                       Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)).unwrap();
+               let route = get_route(&our_id, &payee, &network_graph, None, 60_000, 42, Arc::clone(&logger), &scorer).unwrap();
                // Overpay fees to hit htlc_minimum_msat.
                let overpaid_fees = route.paths[0][0].fee_msat + route.paths[1][0].fee_msat;
                // TODO: this could be better balanced to overpay 10k and not 15k.
@@ -1801,16 +2243,14 @@ mod tests {
                        excess_data: Vec::new()
                });
 
-               let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
-                       Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)).unwrap();
+               let route = get_route(&our_id, &payee, &network_graph, None, 60_000, 42, Arc::clone(&logger), &scorer).unwrap();
                // Fine to overpay for htlc_minimum_msat if it allows us to save fee.
                assert_eq!(route.paths.len(), 1);
                assert_eq!(route.paths[0][0].short_channel_id, 12);
                let fees = route.paths[0][0].fee_msat;
                assert_eq!(fees, 5_000);
 
-               let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
-                       Some(InvoiceFeatures::known()), None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
+               let route = get_route(&our_id, &payee, &network_graph, None, 50_000, 42, Arc::clone(&logger), &scorer).unwrap();
                // Not fine to overpay for htlc_minimum_msat if it requires paying more than fee on
                // the other channel.
                assert_eq!(route.paths.len(), 1);
@@ -1821,8 +2261,10 @@ mod tests {
 
        #[test]
        fn disable_channels_test() {
-               let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
+               let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
                let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
+               let payee = Payee::from_node_id(nodes[2]);
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
 
                // // Disable channels 4 and 12 by flags=2
                update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
@@ -1851,24 +2293,13 @@ mod tests {
                });
 
                // If all the channels require some features we don't understand, route should fail
-               if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)) {
+               if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &payee, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer) {
                        assert_eq!(err, "Failed to find a path to the given destination");
                } else { panic!(); }
 
                // If we specify a channel to node7, that overrides our local channel view and that gets used
-               let our_chans = vec![channelmanager::ChannelDetails {
-                       channel_id: [0; 32],
-                       short_channel_id: Some(42),
-                       remote_network_id: nodes[7].clone(),
-                       counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
-                       channel_value_satoshis: 0,
-                       user_id: 0,
-                       outbound_capacity_msat: 250_000_000,
-                       inbound_capacity_msat: 0,
-                       is_live: true,
-                       counterparty_forwarding_info: None,
-               }];
-               let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()),  &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
+               let our_chans = vec![get_channel_details(Some(42), nodes[7].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
+               let route = get_route(&our_id, &payee, &network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 100, 42, Arc::clone(&logger), &scorer).unwrap();
                assert_eq!(route.paths[0].len(), 2);
 
                assert_eq!(route.paths[0][0].pubkey, nodes[7]);
@@ -1888,35 +2319,25 @@ mod tests {
 
        #[test]
        fn disable_node_test() {
-               let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
+               let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
                let (_, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
+               let payee = Payee::from_node_id(nodes[2]);
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
 
                // Disable nodes 1, 2, and 8 by requiring unknown feature bits
-               let mut unknown_features = NodeFeatures::known();
-               unknown_features.set_required_unknown_bits();
+               let unknown_features = NodeFeatures::known().set_unknown_feature_required();
                add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], unknown_features.clone(), 1);
                add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], unknown_features.clone(), 1);
                add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], unknown_features.clone(), 1);
 
                // If all nodes require some features we don't understand, route should fail
-               if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)) {
+               if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &payee, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer) {
                        assert_eq!(err, "Failed to find a path to the given destination");
                } else { panic!(); }
 
                // If we specify a channel to node7, that overrides our local channel view and that gets used
-               let our_chans = vec![channelmanager::ChannelDetails {
-                       channel_id: [0; 32],
-                       short_channel_id: Some(42),
-                       remote_network_id: nodes[7].clone(),
-                       counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
-                       channel_value_satoshis: 0,
-                       user_id: 0,
-                       outbound_capacity_msat: 250_000_000,
-                       inbound_capacity_msat: 0,
-                       is_live: true,
-                       counterparty_forwarding_info: None,
-               }];
-               let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
+               let our_chans = vec![get_channel_details(Some(42), nodes[7].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
+               let route = get_route(&our_id, &payee, &network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 100, 42, Arc::clone(&logger), &scorer).unwrap();
                assert_eq!(route.paths[0].len(), 2);
 
                assert_eq!(route.paths[0][0].pubkey, nodes[7]);
@@ -1940,11 +2361,13 @@ mod tests {
 
        #[test]
        fn our_chans_test() {
-               let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
+               let (secp_ctx, network_graph, _, _, logger) = build_graph();
                let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
 
                // Route to 1 via 2 and 3 because our channel to 1 is disabled
-               let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[0], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
+               let payee = Payee::from_node_id(nodes[0]);
+               let route = get_route(&our_id, &payee, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
                assert_eq!(route.paths[0].len(), 3);
 
                assert_eq!(route.paths[0][0].pubkey, nodes[1]);
@@ -1969,19 +2392,9 @@ mod tests {
                assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(3));
 
                // If we specify a channel to node7, that overrides our local channel view and that gets used
-               let our_chans = vec![channelmanager::ChannelDetails {
-                       channel_id: [0; 32],
-                       short_channel_id: Some(42),
-                       remote_network_id: nodes[7].clone(),
-                       counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
-                       channel_value_satoshis: 0,
-                       user_id: 0,
-                       outbound_capacity_msat: 250_000_000,
-                       inbound_capacity_msat: 0,
-                       is_live: true,
-                       counterparty_forwarding_info: None,
-               }];
-               let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
+               let payee = Payee::from_node_id(nodes[2]);
+               let our_chans = vec![get_channel_details(Some(42), nodes[7].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
+               let route = get_route(&our_id, &payee, &network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 100, 42, Arc::clone(&logger), &scorer).unwrap();
                assert_eq!(route.paths[0].len(), 2);
 
                assert_eq!(route.paths[0][0].pubkey, nodes[7]);
@@ -2004,15 +2417,59 @@ mod tests {
                        base_msat: 0,
                        proportional_millionths: 0,
                };
-               vec!(RouteHint {
-                       src_node_id: nodes[3].clone(),
+               vec![RouteHint(vec![RouteHintHop {
+                       src_node_id: nodes[3],
+                       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],
+                       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],
+                       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],
+                       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],
                        short_channel_id: 8,
                        fees: zero_fees,
                        cltv_expiry_delta: (8 << 8) | 1,
                        htlc_minimum_msat: None,
                        htlc_maximum_msat: None,
-               }, RouteHint {
-                       src_node_id: nodes[4].clone(),
+               }
+               ]), RouteHint(vec![RouteHintHop {
+                       src_node_id: nodes[4],
                        short_channel_id: 9,
                        fees: RoutingFees {
                                base_msat: 1001,
@@ -2021,25 +2478,28 @@ mod tests {
                        cltv_expiry_delta: (9 << 8) | 1,
                        htlc_minimum_msat: None,
                        htlc_maximum_msat: None,
-               }, RouteHint {
-                       src_node_id: nodes[5].clone(),
+               }]), RouteHint(vec![RouteHintHop {
+                       src_node_id: nodes[5],
                        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_test() {
-               let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
+       fn partial_route_hint_test() {
+               let (secp_ctx, network_graph, _, _, logger) = build_graph();
                let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
 
                // 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 lst hop can't have its source as the payee.
-               let invalid_last_hop = RouteHint {
+               // First check that last hop can't have its source as the payee.
+               let invalid_last_hop = RouteHint(vec![RouteHintHop {
                        src_node_id: nodes[6],
                        short_channel_id: 8,
                        fees: RoutingFees {
@@ -2049,17 +2509,19 @@ mod tests {
                        cltv_expiry_delta: (8 << 8) | 1,
                        htlc_minimum_msat: None,
                        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)) {
-                               assert_eq!(err, "Last hop cannot have a payee as a source.");
+                       let payee = Payee::from_node_id(nodes[6]).with_route_hints(invalid_last_hops);
+                       if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &payee, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer) {
+                               assert_eq!(err, "Route hint cannot have the payee as the source.");
                        } 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 payee = Payee::from_node_id(nodes[6]).with_route_hints(last_hops_multi_private_channels(&nodes));
+               let route = get_route(&our_id, &payee, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
                assert_eq!(route.paths[0].len(), 5);
 
                assert_eq!(route.paths[0][0].pubkey, nodes[1]);
@@ -2100,47 +2562,301 @@ mod tests {
                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();
-               let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
-
-               // Simple test with outbound channel to 4 to test that last_hops and first_hops connect
-               let our_chans = vec![channelmanager::ChannelDetails {
-                       channel_id: [0; 32],
-                       short_channel_id: Some(42),
-                       remote_network_id: nodes[3].clone(),
-                       counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
-                       channel_value_satoshis: 0,
-                       user_id: 0,
-                       outbound_capacity_msat: 250_000_000,
-                       inbound_capacity_msat: 0,
-                       is_live: true,
-                       counterparty_forwarding_info: None,
-               }];
-               let mut last_hops = last_hops(&nodes);
-               let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, Some(&our_chans.iter().collect::<Vec<_>>()), &last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
-               assert_eq!(route.paths[0].len(), 2);
+       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],
+                       short_channel_id: 8,
+                       fees: zero_fees,
+                       cltv_expiry_delta: (8 << 8) | 1,
+                       htlc_minimum_msat: None,
+                       htlc_maximum_msat: None,
+               }]), RouteHint(vec![
 
-               assert_eq!(route.paths[0][0].pubkey, nodes[3]);
-               assert_eq!(route.paths[0][0].short_channel_id, 42);
-               assert_eq!(route.paths[0][0].fee_msat, 0);
-               assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
-               assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
-               assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
+               ]), RouteHint(vec![RouteHintHop {
+                       src_node_id: nodes[5],
+                       short_channel_id: 10,
+                       fees: zero_fees,
+                       cltv_expiry_delta: (10 << 8) | 1,
+                       htlc_minimum_msat: None,
+                       htlc_maximum_msat: None,
+               }])]
+       }
 
-               assert_eq!(route.paths[0][1].pubkey, nodes[6]);
-               assert_eq!(route.paths[0][1].short_channel_id, 8);
-               assert_eq!(route.paths[0][1].fee_msat, 100);
-               assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
-               assert_eq!(route.paths[0][1].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
-               assert_eq!(route.paths[0][1].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
+       #[test]
+       fn ignores_empty_last_hops_test() {
+               let (secp_ctx, network_graph, _, _, logger) = build_graph();
+               let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
+               let payee = Payee::from_node_id(nodes[6]).with_route_hints(empty_last_hop(&nodes));
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
 
-               last_hops[0].fees.base_msat = 1000;
+               // Test handling of an empty RouteHint passed in Invoice.
 
-               // Revert to via 6 as the fee on 8 goes up
-               let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
-               assert_eq!(route.paths[0].len(), 4);
+               let route = get_route(&our_id, &payee, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).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 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],
+                       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],
+                       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],
+                       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, network_graph, net_graph_msg_handler, _, logger) = build_graph();
+               let (_, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
+               let payee = Payee::from_node_id(nodes[6]).with_route_hints(multi_hint_last_hops(&nodes));
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
+               // 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, &payee, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).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],
+                       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],
+                       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],
+                       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],
+                       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, network_graph, _, _, logger) = build_graph();
+               let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
+               let payee = Payee::from_node_id(nodes[6]).with_route_hints(last_hops_with_public_channel(&nodes));
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
+               // 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, &payee, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).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, network_graph, _, _, logger) = build_graph();
+               let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
+
+               // Simple test with outbound channel to 4 to test that last_hops and first_hops connect
+               let our_chans = vec![get_channel_details(Some(42), nodes[3].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
+               let mut last_hops = last_hops(&nodes);
+               let payee = Payee::from_node_id(nodes[6]).with_route_hints(last_hops.clone());
+               let route = get_route(&our_id, &payee, &network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 100, 42, Arc::clone(&logger), &scorer).unwrap();
+               assert_eq!(route.paths[0].len(), 2);
+
+               assert_eq!(route.paths[0][0].pubkey, nodes[3]);
+               assert_eq!(route.paths[0][0].short_channel_id, 42);
+               assert_eq!(route.paths[0][0].fee_msat, 0);
+               assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
+               assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
+               assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
+
+               assert_eq!(route.paths[0][1].pubkey, nodes[6]);
+               assert_eq!(route.paths[0][1].short_channel_id, 8);
+               assert_eq!(route.paths[0][1].fee_msat, 100);
+               assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
+               assert_eq!(route.paths[0][1].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
+               assert_eq!(route.paths[0][1].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
+
+               last_hops[0].0[0].fees.base_msat = 1000;
+
+               // Revert to via 6 as the fee on 8 goes up
+               let payee = Payee::from_node_id(nodes[6]).with_route_hints(last_hops);
+               let route = get_route(&our_id, &payee, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).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);
@@ -2173,7 +2889,7 @@ mod tests {
                assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
 
                // ...but still use 8 for larger payments as 6 has a variable feerate
-               let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &last_hops.iter().collect::<Vec<_>>(), 2000, 42, Arc::clone(&logger)).unwrap();
+               let route = get_route(&our_id, &payee, &network_graph, None, 2000, 42, Arc::clone(&logger), &scorer).unwrap();
                assert_eq!(route.paths[0].len(), 5);
 
                assert_eq!(route.paths[0][0].pubkey, nodes[1]);
@@ -2214,64 +2930,81 @@ mod tests {
                assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
        }
 
-       #[test]
-       fn unannounced_path_test() {
-               // We should be able to send a payment to a destination without any help of a routing graph
-               // if we have a channel with a common counterparty that appears in the first and last hop
-               // hints.
+       fn do_unannounced_path_test(last_hop_htlc_max: Option<u64>, last_hop_fee_prop: u32, outbound_capacity_msat: u64, route_val: u64) -> Result<Route, LightningError> {
                let source_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 41).repeat(32)).unwrap()[..]).unwrap());
                let middle_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 42).repeat(32)).unwrap()[..]).unwrap());
                let target_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 43).repeat(32)).unwrap()[..]).unwrap());
 
                // If we specify a channel to a middle hop, that overrides our local channel view and that gets used
-               let last_hops = vec![RouteHint {
+               let last_hops = RouteHint(vec![RouteHintHop {
                        src_node_id: middle_node_id,
                        short_channel_id: 8,
                        fees: RoutingFees {
                                base_msat: 1000,
-                               proportional_millionths: 0,
+                               proportional_millionths: last_hop_fee_prop,
                        },
                        cltv_expiry_delta: (8 << 8) | 1,
                        htlc_minimum_msat: None,
-                       htlc_maximum_msat: None,
-               }];
-               let our_chans = vec![channelmanager::ChannelDetails {
-                       channel_id: [0; 32],
-                       short_channel_id: Some(42),
-                       remote_network_id: middle_node_id,
-                       counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
-                       channel_value_satoshis: 100000,
-                       user_id: 0,
-                       outbound_capacity_msat: 100000,
-                       inbound_capacity_msat: 100000,
-                       is_live: true,
-                       counterparty_forwarding_info: None,
-               }];
-               let route = get_route(&source_node_id, &NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash()), &target_node_id, None, Some(&our_chans.iter().collect::<Vec<_>>()), &last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::new(test_utils::TestLogger::new())).unwrap();
+                       htlc_maximum_msat: last_hop_htlc_max,
+               }]);
+               let payee = Payee::from_node_id(target_node_id).with_route_hints(vec![last_hops]);
+               let our_chans = vec![get_channel_details(Some(42), middle_node_id, InitFeatures::from_le_bytes(vec![0b11]), outbound_capacity_msat)];
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
+               get_route(&source_node_id, &payee, &NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash()), Some(&our_chans.iter().collect::<Vec<_>>()), route_val, 42, &test_utils::TestLogger::new(), &scorer)
+       }
+
+       #[test]
+       fn unannounced_path_test() {
+               // We should be able to send a payment to a destination without any help of a routing graph
+               // if we have a channel with a common counterparty that appears in the first and last hop
+               // hints.
+               let route = do_unannounced_path_test(None, 1, 2000000, 1000000).unwrap();
 
+               let middle_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 42).repeat(32)).unwrap()[..]).unwrap());
+               let target_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 43).repeat(32)).unwrap()[..]).unwrap());
                assert_eq!(route.paths[0].len(), 2);
 
                assert_eq!(route.paths[0][0].pubkey, middle_node_id);
                assert_eq!(route.paths[0][0].short_channel_id, 42);
-               assert_eq!(route.paths[0][0].fee_msat, 1000);
+               assert_eq!(route.paths[0][0].fee_msat, 1001);
                assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
                assert_eq!(route.paths[0][0].node_features.le_flags(), &[0b11]);
                assert_eq!(route.paths[0][0].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
 
                assert_eq!(route.paths[0][1].pubkey, target_node_id);
                assert_eq!(route.paths[0][1].short_channel_id, 8);
-               assert_eq!(route.paths[0][1].fee_msat, 100);
+               assert_eq!(route.paths[0][1].fee_msat, 1000000);
                assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
                assert_eq!(route.paths[0][1].node_features.le_flags(), &[0; 0]); // We dont pass flags in from invoices yet
                assert_eq!(route.paths[0][1].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
        }
 
+       #[test]
+       fn overflow_unannounced_path_test_liquidity_underflow() {
+               // Previously, when we had a last-hop hint connected directly to a first-hop channel, where
+               // the last-hop had a fee which overflowed a u64, we'd panic.
+               // This was due to us adding the first-hop from us unconditionally, causing us to think
+               // we'd built a path (as our node is in the "best candidate" set), when we had not.
+               // In this test, we previously hit a subtraction underflow due to having less available
+               // liquidity at the last hop than 0.
+               assert!(do_unannounced_path_test(Some(21_000_000_0000_0000_000), 0, 21_000_000_0000_0000_000, 21_000_000_0000_0000_000).is_err());
+       }
+
+       #[test]
+       fn overflow_unannounced_path_test_feerate_overflow() {
+               // This tests for the same case as above, except instead of hitting a subtraction
+               // underflow, we hit a case where the fee charged at a hop overflowed.
+               assert!(do_unannounced_path_test(Some(21_000_000_0000_0000_000), 50000, 21_000_000_0000_0000_000, 21_000_000_0000_0000_000).is_err());
+       }
+
        #[test]
        fn available_amount_while_routing_test() {
                // Tests whether we choose the correct available channel amount while routing.
 
-               let (secp_ctx, mut net_graph_msg_handler, chain_monitor, logger) = build_graph();
+               let (secp_ctx, network_graph, mut net_graph_msg_handler, chain_monitor, logger) = build_graph();
                let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
+               let payee = Payee::from_node_id(nodes[2]).with_features(InvoiceFeatures::known());
 
                // We will use a simple single-path route from
                // our node to node2 via node0: channels {1, 3}.
@@ -2334,16 +3067,15 @@ mod tests {
 
                {
                        // Attempt to route more than available results in a failure.
-                       if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
-                                       Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000_001, 42, Arc::clone(&logger)) {
+                       if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
+                                       &our_id, &payee, &network_graph, None, 250_000_001, 42, Arc::clone(&logger), &scorer) {
                                assert_eq!(err, "Failed to find a sufficient route to the given destination");
                        } else { panic!(); }
                }
 
                {
                        // Now, attempt to route an exact amount we have should be fine.
-                       let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
-                               Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000_000, 42, Arc::clone(&logger)).unwrap();
+                       let route = get_route(&our_id, &payee, &network_graph, None, 250_000_000, 42, Arc::clone(&logger), &scorer).unwrap();
                        assert_eq!(route.paths.len(), 1);
                        let path = route.paths.last().unwrap();
                        assert_eq!(path.len(), 2);
@@ -2367,31 +3099,19 @@ mod tests {
                });
 
                // Now, limit the first_hop by the outbound_capacity_msat of 200_000 sats.
-               let our_chans = vec![channelmanager::ChannelDetails {
-                       channel_id: [0; 32],
-                       short_channel_id: Some(42),
-                       remote_network_id: nodes[0].clone(),
-                       counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
-                       channel_value_satoshis: 0,
-                       user_id: 0,
-                       outbound_capacity_msat: 200_000_000,
-                       inbound_capacity_msat: 0,
-                       is_live: true,
-                       counterparty_forwarding_info: None,
-               }];
+               let our_chans = vec![get_channel_details(Some(42), nodes[0].clone(), InitFeatures::from_le_bytes(vec![0b11]), 200_000_000)];
 
                {
                        // Attempt to route more than available results in a failure.
-                       if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
-                                       Some(InvoiceFeatures::known()), Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_001, 42, Arc::clone(&logger)) {
+                       if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
+                                       &our_id, &payee, &network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 200_000_001, 42, Arc::clone(&logger), &scorer) {
                                assert_eq!(err, "Failed to find a sufficient route to the given destination");
                        } else { panic!(); }
                }
 
                {
                        // Now, attempt to route an exact amount we have should be fine.
-                       let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
-                               Some(InvoiceFeatures::known()), Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_000, 42, Arc::clone(&logger)).unwrap();
+                       let route = get_route(&our_id, &payee, &network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 200_000_000, 42, Arc::clone(&logger), &scorer).unwrap();
                        assert_eq!(route.paths.len(), 1);
                        let path = route.paths.last().unwrap();
                        assert_eq!(path.len(), 2);
@@ -2430,16 +3150,15 @@ mod tests {
 
                {
                        // Attempt to route more than available results in a failure.
-                       if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
-                                       Some(InvoiceFeatures::known()), None, &Vec::new(), 15_001, 42, Arc::clone(&logger)) {
+                       if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
+                                       &our_id, &payee, &network_graph, None, 15_001, 42, Arc::clone(&logger), &scorer) {
                                assert_eq!(err, "Failed to find a sufficient route to the given destination");
                        } else { panic!(); }
                }
 
                {
                        // Now, attempt to route an exact amount we have should be fine.
-                       let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
-                               Some(InvoiceFeatures::known()), None, &Vec::new(), 15_000, 42, Arc::clone(&logger)).unwrap();
+                       let route = get_route(&our_id, &payee, &network_graph, None, 15_000, 42, Arc::clone(&logger), &scorer).unwrap();
                        assert_eq!(route.paths.len(), 1);
                        let path = route.paths.last().unwrap();
                        assert_eq!(path.len(), 2);
@@ -2501,16 +3220,15 @@ mod tests {
 
                {
                        // Attempt to route more than available results in a failure.
-                       if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
-                                       Some(InvoiceFeatures::known()), None, &Vec::new(), 15_001, 42, Arc::clone(&logger)) {
+                       if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
+                                       &our_id, &payee, &network_graph, None, 15_001, 42, Arc::clone(&logger), &scorer) {
                                assert_eq!(err, "Failed to find a sufficient route to the given destination");
                        } else { panic!(); }
                }
 
                {
                        // Now, attempt to route an exact amount we have should be fine.
-                       let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
-                               Some(InvoiceFeatures::known()), None, &Vec::new(), 15_000, 42, Arc::clone(&logger)).unwrap();
+                       let route = get_route(&our_id, &payee, &network_graph, None, 15_000, 42, Arc::clone(&logger), &scorer).unwrap();
                        assert_eq!(route.paths.len(), 1);
                        let path = route.paths.last().unwrap();
                        assert_eq!(path.len(), 2);
@@ -2534,16 +3252,15 @@ mod tests {
 
                {
                        // Attempt to route more than available results in a failure.
-                       if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
-                                       Some(InvoiceFeatures::known()), None, &Vec::new(), 10_001, 42, Arc::clone(&logger)) {
+                       if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
+                                       &our_id, &payee, &network_graph, None, 10_001, 42, Arc::clone(&logger), &scorer) {
                                assert_eq!(err, "Failed to find a sufficient route to the given destination");
                        } else { panic!(); }
                }
 
                {
                        // Now, attempt to route an exact amount we have should be fine.
-                       let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
-                               Some(InvoiceFeatures::known()), None, &Vec::new(), 10_000, 42, Arc::clone(&logger)).unwrap();
+                       let route = get_route(&our_id, &payee, &network_graph, None, 10_000, 42, Arc::clone(&logger), &scorer).unwrap();
                        assert_eq!(route.paths.len(), 1);
                        let path = route.paths.last().unwrap();
                        assert_eq!(path.len(), 2);
@@ -2556,8 +3273,10 @@ mod tests {
        fn available_liquidity_last_hop_test() {
                // Check that available liquidity properly limits the path even when only
                // one of the latter hops is limited.
-               let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
+               let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
                let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
+               let payee = Payee::from_node_id(nodes[3]).with_features(InvoiceFeatures::known());
 
                // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
                // {12, 13, 11} have the capacities of 100, {6} has a capacity of 50.
@@ -2642,16 +3361,15 @@ mod tests {
                });
                {
                        // Attempt to route more than available results in a failure.
-                       if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
-                                       Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)) {
+                       if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
+                                       &our_id, &payee, &network_graph, None, 60_000, 42, Arc::clone(&logger), &scorer) {
                                assert_eq!(err, "Failed to find a sufficient route to the given destination");
                        } else { panic!(); }
                }
 
                {
                        // Now, attempt to route 49 sats (just a bit below the capacity).
-                       let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
-                               Some(InvoiceFeatures::known()), None, &Vec::new(), 49_000, 42, Arc::clone(&logger)).unwrap();
+                       let route = get_route(&our_id, &payee, &network_graph, None, 49_000, 42, Arc::clone(&logger), &scorer).unwrap();
                        assert_eq!(route.paths.len(), 1);
                        let mut total_amount_paid_msat = 0;
                        for path in &route.paths {
@@ -2664,8 +3382,7 @@ mod tests {
 
                {
                        // Attempt to route an exact amount is also fine
-                       let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
-                               Some(InvoiceFeatures::known()), None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
+                       let route = get_route(&our_id, &payee, &network_graph, None, 50_000, 42, Arc::clone(&logger), &scorer).unwrap();
                        assert_eq!(route.paths.len(), 1);
                        let mut total_amount_paid_msat = 0;
                        for path in &route.paths {
@@ -2679,8 +3396,10 @@ mod tests {
 
        #[test]
        fn ignore_fee_first_hop_test() {
-               let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
+               let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
                let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
+               let payee = Payee::from_node_id(nodes[2]);
 
                // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
                update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
@@ -2709,7 +3428,7 @@ mod tests {
                });
 
                {
-                       let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
+                       let route = get_route(&our_id, &payee, &network_graph, None, 50_000, 42, Arc::clone(&logger), &scorer).unwrap();
                        assert_eq!(route.paths.len(), 1);
                        let mut total_amount_paid_msat = 0;
                        for path in &route.paths {
@@ -2723,8 +3442,10 @@ mod tests {
 
        #[test]
        fn simple_mpp_route_test() {
-               let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
+               let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
                let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
+               let payee = Payee::from_node_id(nodes[2]).with_features(InvoiceFeatures::known());
 
                // We need a route consisting of 3 paths:
                // From our node to node2 via node0, node7, node1 (three paths one hop each).
@@ -2816,8 +3537,8 @@ mod tests {
 
                {
                        // Attempt to route more than available results in a failure.
-                       if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(),
-                                       &nodes[2], Some(InvoiceFeatures::known()), None, &Vec::new(), 300_000, 42, Arc::clone(&logger)) {
+                       if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
+                                       &our_id, &payee, &network_graph, None, 300_000, 42, Arc::clone(&logger), &scorer) {
                                assert_eq!(err, "Failed to find a sufficient route to the given destination");
                        } else { panic!(); }
                }
@@ -2825,8 +3546,7 @@ mod tests {
                {
                        // Now, attempt to route 250 sats (just a bit below the capacity).
                        // Our algorithm should provide us with these 3 paths.
-                       let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
-                               Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000, 42, Arc::clone(&logger)).unwrap();
+                       let route = get_route(&our_id, &payee, &network_graph, None, 250_000, 42, Arc::clone(&logger), &scorer).unwrap();
                        assert_eq!(route.paths.len(), 3);
                        let mut total_amount_paid_msat = 0;
                        for path in &route.paths {
@@ -2839,8 +3559,7 @@ mod tests {
 
                {
                        // Attempt to route an exact amount is also fine
-                       let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
-                               Some(InvoiceFeatures::known()), None, &Vec::new(), 290_000, 42, Arc::clone(&logger)).unwrap();
+                       let route = get_route(&our_id, &payee, &network_graph, None, 290_000, 42, Arc::clone(&logger), &scorer).unwrap();
                        assert_eq!(route.paths.len(), 3);
                        let mut total_amount_paid_msat = 0;
                        for path in &route.paths {
@@ -2854,8 +3573,10 @@ mod tests {
 
        #[test]
        fn long_mpp_route_test() {
-               let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
+               let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
                let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
+               let payee = Payee::from_node_id(nodes[3]).with_features(InvoiceFeatures::known());
 
                // We need a route consisting of 3 paths:
                // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
@@ -2990,8 +3711,8 @@ mod tests {
 
                {
                        // Attempt to route more than available results in a failure.
-                       if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
-                                       Some(InvoiceFeatures::known()), None, &Vec::new(), 350_000, 42, Arc::clone(&logger)) {
+                       if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
+                                       &our_id, &payee, &network_graph, None, 350_000, 42, Arc::clone(&logger), &scorer) {
                                assert_eq!(err, "Failed to find a sufficient route to the given destination");
                        } else { panic!(); }
                }
@@ -2999,8 +3720,7 @@ mod tests {
                {
                        // Now, attempt to route 300 sats (exact amount we can route).
                        // Our algorithm should provide us with these 3 paths, 100 sats each.
-                       let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
-                               Some(InvoiceFeatures::known()), None, &Vec::new(), 300_000, 42, Arc::clone(&logger)).unwrap();
+                       let route = get_route(&our_id, &payee, &network_graph, None, 300_000, 42, Arc::clone(&logger), &scorer).unwrap();
                        assert_eq!(route.paths.len(), 3);
 
                        let mut total_amount_paid_msat = 0;
@@ -3015,8 +3735,10 @@ mod tests {
 
        #[test]
        fn mpp_cheaper_route_test() {
-               let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
+               let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
                let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
+               let payee = Payee::from_node_id(nodes[3]).with_features(InvoiceFeatures::known());
 
                // This test checks that if we have two cheaper paths and one more expensive path,
                // so that liquidity-wise any 2 of 3 combination is sufficient,
@@ -3156,8 +3878,7 @@ mod tests {
                {
                        // Now, attempt to route 180 sats.
                        // Our algorithm should provide us with these 2 paths.
-                       let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
-                               Some(InvoiceFeatures::known()), None, &Vec::new(), 180_000, 42, Arc::clone(&logger)).unwrap();
+                       let route = get_route(&our_id, &payee, &network_graph, None, 180_000, 42, Arc::clone(&logger), &scorer).unwrap();
                        assert_eq!(route.paths.len(), 2);
 
                        let mut total_value_transferred_msat = 0;
@@ -3181,8 +3902,10 @@ mod tests {
                // This test makes sure that MPP algorithm properly takes into account
                // fees charged on the channels, by making the fees impactful:
                // if the fee is not properly accounted for, the behavior is different.
-               let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
+               let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
                let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
+               let payee = Payee::from_node_id(nodes[3]).with_features(InvoiceFeatures::known());
 
                // We need a route consisting of 2 paths:
                // From our node to node3 via {node0, node2} and {node7, node2, node4}.
@@ -3322,16 +4045,15 @@ mod tests {
 
                {
                        // Attempt to route more than available results in a failure.
-                       if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
-                                       Some(InvoiceFeatures::known()), None, &Vec::new(), 210_000, 42, Arc::clone(&logger)) {
+                       if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
+                                       &our_id, &payee, &network_graph, None, 210_000, 42, Arc::clone(&logger), &scorer) {
                                assert_eq!(err, "Failed to find a sufficient route to the given destination");
                        } else { panic!(); }
                }
 
                {
                        // Now, attempt to route 200 sats (exact amount we can route).
-                       let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
-                               Some(InvoiceFeatures::known()), None, &Vec::new(), 200_000, 42, Arc::clone(&logger)).unwrap();
+                       let route = get_route(&our_id, &payee, &network_graph, None, 200_000, 42, Arc::clone(&logger), &scorer).unwrap();
                        assert_eq!(route.paths.len(), 2);
 
                        let mut total_amount_paid_msat = 0;
@@ -3340,16 +4062,117 @@ mod tests {
                                total_amount_paid_msat += path.last().unwrap().fee_msat;
                        }
                        assert_eq!(total_amount_paid_msat, 200_000);
+                       assert_eq!(route.get_total_fees(), 150_000);
                }
+       }
+
+       #[test]
+       fn mpp_with_last_hops() {
+               // Previously, if we tried to send an MPP payment to a destination which was only reachable
+               // via a single last-hop route hint, we'd fail to route if we first collected routes
+               // totaling close but not quite enough to fund the full payment.
+               //
+               // This was because we considered last-hop hints to have exactly the sought payment amount
+               // instead of the amount we were trying to collect, needlessly limiting our path searching
+               // at the very first hop.
+               //
+               // Specifically, this interacted with our "all paths must fund at least 5% of total target"
+               // criterion to cause us to refuse all routes at the last hop hint which would be considered
+               // to only have the remaining to-collect amount in available liquidity.
+               //
+               // This bug appeared in production in some specific channel configurations.
+               let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
+               let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
+               let payee = Payee::from_node_id(PublicKey::from_slice(&[02; 33]).unwrap()).with_features(InvoiceFeatures::known())
+                       .with_route_hints(vec![RouteHint(vec![RouteHintHop {
+                               src_node_id: nodes[2],
+                               short_channel_id: 42,
+                               fees: RoutingFees { base_msat: 0, proportional_millionths: 0 },
+                               cltv_expiry_delta: 42,
+                               htlc_minimum_msat: None,
+                               htlc_maximum_msat: None,
+                       }])]);
+
+               // Keep only two paths from us to nodes[2], both with a 99sat HTLC maximum, with one with
+               // no fee and one with a 1msat fee. Previously, trying to route 100 sats to nodes[2] here
+               // would first use the no-fee route and then fail to find a path along the second route as
+               // we think we can only send up to 1 additional sat over the last-hop but refuse to as its
+               // under 5% of our payment amount.
+               update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
+                       chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+                       short_channel_id: 1,
+                       timestamp: 2,
+                       flags: 0,
+                       cltv_expiry_delta: u16::max_value(),
+                       htlc_minimum_msat: 0,
+                       htlc_maximum_msat: OptionalField::Present(99_000),
+                       fee_base_msat: u32::max_value(),
+                       fee_proportional_millionths: u32::max_value(),
+                       excess_data: Vec::new()
+               });
+               update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
+                       chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+                       short_channel_id: 2,
+                       timestamp: 2,
+                       flags: 0,
+                       cltv_expiry_delta: u16::max_value(),
+                       htlc_minimum_msat: 0,
+                       htlc_maximum_msat: OptionalField::Present(99_000),
+                       fee_base_msat: u32::max_value(),
+                       fee_proportional_millionths: u32::max_value(),
+                       excess_data: Vec::new()
+               });
+               update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
+                       chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+                       short_channel_id: 4,
+                       timestamp: 2,
+                       flags: 0,
+                       cltv_expiry_delta: (4 << 8) | 1,
+                       htlc_minimum_msat: 0,
+                       htlc_maximum_msat: OptionalField::Absent,
+                       fee_base_msat: 1,
+                       fee_proportional_millionths: 0,
+                       excess_data: Vec::new()
+               });
+               update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
+                       chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+                       short_channel_id: 13,
+                       timestamp: 2,
+                       flags: 0|2, // Channel disabled
+                       cltv_expiry_delta: (13 << 8) | 1,
+                       htlc_minimum_msat: 0,
+                       htlc_maximum_msat: OptionalField::Absent,
+                       fee_base_msat: 0,
+                       fee_proportional_millionths: 2000000,
+                       excess_data: Vec::new()
+               });
 
+               // Get a route for 100 sats and check that we found the MPP route no problem and didn't
+               // overpay at all.
+               let route = get_route(&our_id, &payee, &network_graph, None, 100_000, 42, Arc::clone(&logger), &scorer).unwrap();
+               assert_eq!(route.paths.len(), 2);
+               // Paths are somewhat randomly ordered, but:
+               // * the first is channel 2 (1 msat fee) -> channel 4 -> channel 42
+               // * the second is channel 1 (0 fee, but 99 sat maximum) -> channel 3 -> channel 42
+               assert_eq!(route.paths[0][0].short_channel_id, 2);
+               assert_eq!(route.paths[0][0].fee_msat, 1);
+               assert_eq!(route.paths[0][2].fee_msat, 1_000);
+               assert_eq!(route.paths[1][0].short_channel_id, 1);
+               assert_eq!(route.paths[1][0].fee_msat, 0);
+               assert_eq!(route.paths[1][2].fee_msat, 99_000);
+               assert_eq!(route.get_total_fees(), 1);
+               assert_eq!(route.get_total_amount(), 100_000);
        }
 
        #[test]
        fn drop_lowest_channel_mpp_route_test() {
                // This test checks that low-capacity channel is dropped when after
                // path finding we realize that we found more capacity than we need.
-               let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
+               let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
                let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
+               let payee = Payee::from_node_id(nodes[2]).with_features(InvoiceFeatures::known());
 
                // We need a route consisting of 3 paths:
                // From our node to node2 via node0, node7, node1 (three paths one hop each).
@@ -3440,8 +4263,8 @@ mod tests {
 
                {
                        // Attempt to route more than available results in a failure.
-                       if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
-                                       Some(InvoiceFeatures::known()), None, &Vec::new(), 150_000, 42, Arc::clone(&logger)) {
+                       if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
+                                       &our_id, &payee, &network_graph, None, 150_000, 42, Arc::clone(&logger), &scorer) {
                                assert_eq!(err, "Failed to find a sufficient route to the given destination");
                        } else { panic!(); }
                }
@@ -3449,8 +4272,7 @@ mod tests {
                {
                        // Now, attempt to route 125 sats (just a bit below the capacity of 3 channels).
                        // Our algorithm should provide us with these 3 paths.
-                       let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
-                               Some(InvoiceFeatures::known()), None, &Vec::new(), 125_000, 42, Arc::clone(&logger)).unwrap();
+                       let route = get_route(&our_id, &payee, &network_graph, None, 125_000, 42, Arc::clone(&logger), &scorer).unwrap();
                        assert_eq!(route.paths.len(), 3);
                        let mut total_amount_paid_msat = 0;
                        for path in &route.paths {
@@ -3463,8 +4285,7 @@ mod tests {
 
                {
                        // Attempt to route without the last small cheap channel
-                       let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
-                               Some(InvoiceFeatures::known()), None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
+                       let route = get_route(&our_id, &payee, &network_graph, None, 90_000, 42, Arc::clone(&logger), &scorer).unwrap();
                        assert_eq!(route.paths.len(), 2);
                        let mut total_amount_paid_msat = 0;
                        for path in &route.paths {
@@ -3504,8 +4325,11 @@ mod tests {
                // "previous hop" being set to node 3, creating a loop in the path.
                let secp_ctx = Secp256k1::new();
                let logger = Arc::new(test_utils::TestLogger::new());
-               let net_graph_msg_handler = NetGraphMsgHandler::new(genesis_block(Network::Testnet).header.block_hash(), None, Arc::clone(&logger));
+               let network_graph = Arc::new(NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash()));
+               let net_graph_msg_handler = NetGraphMsgHandler::new(Arc::clone(&network_graph), None, Arc::clone(&logger));
                let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
+               let payee = Payee::from_node_id(nodes[6]);
 
                add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
                update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
@@ -3598,7 +4422,7 @@ mod tests {
 
                {
                        // Now ensure the route flows simply over nodes 1 and 4 to 6.
-                       let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &Vec::new(), 10_000, 42, Arc::clone(&logger)).unwrap();
+                       let route = get_route(&our_id, &payee, &network_graph, None, 10_000, 42, Arc::clone(&logger), &scorer).unwrap();
                        assert_eq!(route.paths.len(), 1);
                        assert_eq!(route.paths[0].len(), 3);
 
@@ -3631,8 +4455,10 @@ mod tests {
                // Test that if, while walking the graph, we find a hop that has exactly enough liquidity
                // for us, including later hop fees, we take it. In the first version of our MPP algorithm
                // we calculated fees on a higher value, resulting in us ignoring such paths.
-               let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
+               let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
                let (our_privkey, our_id, _, nodes) = get_nodes(&secp_ctx);
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
+               let payee = Payee::from_node_id(nodes[2]);
 
                // We modify the graph to set the htlc_maximum of channel 2 to below the value we wish to
                // send.
@@ -3665,7 +4491,7 @@ mod tests {
                {
                        // Now, attempt to route 90 sats, which is exactly 90 sats at the last hop, plus the
                        // 200% fee charged channel 13 in the 1-to-2 direction.
-                       let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
+                       let route = get_route(&our_id, &payee, &network_graph, None, 90_000, 42, Arc::clone(&logger), &scorer).unwrap();
                        assert_eq!(route.paths.len(), 1);
                        assert_eq!(route.paths[0].len(), 2);
 
@@ -3691,8 +4517,10 @@ mod tests {
                // htlc_maximum_msat, we don't end up undershooting a later htlc_minimum_msat. In the
                // initial version of MPP we'd accept such routes but reject them while recalculating fees,
                // resulting in us thinking there is no possible path, even if other paths exist.
-               let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
+               let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
                let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
+               let payee = Payee::from_node_id(nodes[2]).with_features(InvoiceFeatures::known());
 
                // We modify the graph to set the htlc_minimum of channel 2 and 4 as needed - channel 2
                // gets an htlc_maximum_msat of 80_000 and channel 4 an htlc_minimum_msat of 90_000. We
@@ -3726,7 +4554,7 @@ mod tests {
                        // Now, attempt to route 90 sats, hitting the htlc_minimum on channel 4, but
                        // overshooting the htlc_maximum on channel 2. Thus, we should pick the (absurdly
                        // expensive) channels 12-13 path.
-                       let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], Some(InvoiceFeatures::known()), None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
+                       let route = get_route(&our_id, &payee, &network_graph, None, 90_000, 42, Arc::clone(&logger), &scorer).unwrap();
                        assert_eq!(route.paths.len(), 1);
                        assert_eq!(route.paths[0].len(), 2);
 
@@ -3745,14 +4573,341 @@ mod tests {
                        assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
                }
        }
+
+       #[test]
+       fn multiple_direct_first_hops() {
+               // Previously we'd only ever considered one first hop path per counterparty.
+               // However, as we don't restrict users to one channel per peer, we really need to support
+               // looking at all first hop paths.
+               // Here we test that we do not ignore all-but-the-last first hop paths per counterparty (as
+               // we used to do by overwriting the `first_hop_targets` hashmap entry) and that we can MPP
+               // route over multiple channels with the same first hop.
+               let secp_ctx = Secp256k1::new();
+               let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
+               let logger = Arc::new(test_utils::TestLogger::new());
+               let network_graph = NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash());
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
+               let payee = Payee::from_node_id(nodes[0]).with_features(InvoiceFeatures::known());
+
+               {
+                       let route = get_route(&our_id, &payee, &network_graph, Some(&[
+                               &get_channel_details(Some(3), nodes[0], InitFeatures::known(), 200_000),
+                               &get_channel_details(Some(2), nodes[0], InitFeatures::known(), 10_000),
+                       ]), 100_000, 42, Arc::clone(&logger), &scorer).unwrap();
+                       assert_eq!(route.paths.len(), 1);
+                       assert_eq!(route.paths[0].len(), 1);
+
+                       assert_eq!(route.paths[0][0].pubkey, nodes[0]);
+                       assert_eq!(route.paths[0][0].short_channel_id, 3);
+                       assert_eq!(route.paths[0][0].fee_msat, 100_000);
+               }
+               {
+                       let route = get_route(&our_id, &payee, &network_graph, Some(&[
+                               &get_channel_details(Some(3), nodes[0], InitFeatures::known(), 50_000),
+                               &get_channel_details(Some(2), nodes[0], InitFeatures::known(), 50_000),
+                       ]), 100_000, 42, Arc::clone(&logger), &scorer).unwrap();
+                       assert_eq!(route.paths.len(), 2);
+                       assert_eq!(route.paths[0].len(), 1);
+                       assert_eq!(route.paths[1].len(), 1);
+
+                       assert_eq!(route.paths[0][0].pubkey, nodes[0]);
+                       assert_eq!(route.paths[0][0].short_channel_id, 3);
+                       assert_eq!(route.paths[0][0].fee_msat, 50_000);
+
+                       assert_eq!(route.paths[1][0].pubkey, nodes[0]);
+                       assert_eq!(route.paths[1][0].short_channel_id, 2);
+                       assert_eq!(route.paths[1][0].fee_msat, 50_000);
+               }
+       }
+
+       #[test]
+       fn prefers_shorter_route_with_higher_fees() {
+               let (secp_ctx, network_graph, _, _, logger) = build_graph();
+               let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
+               let payee = Payee::from_node_id(nodes[6]).with_route_hints(last_hops(&nodes));
+
+               // Without penalizing each hop 100 msats, a longer path with lower fees is chosen.
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
+               let route = get_route(
+                       &our_id, &payee, &network_graph, None, 100, 42,
+                       Arc::clone(&logger), &scorer
+               ).unwrap();
+               let path = route.paths[0].iter().map(|hop| hop.short_channel_id).collect::<Vec<_>>();
+
+               assert_eq!(route.get_total_fees(), 100);
+               assert_eq!(route.get_total_amount(), 100);
+               assert_eq!(path, vec![2, 4, 6, 11, 8]);
+
+               // Applying a 100 msat penalty to each hop results in taking channels 7 and 10 to nodes[6]
+               // from nodes[2] rather than channel 6, 11, and 8, even though the longer path is cheaper.
+               let scorer = test_utils::TestScorer::with_fixed_penalty(100);
+               let route = get_route(
+                       &our_id, &payee, &network_graph, None, 100, 42,
+                       Arc::clone(&logger), &scorer
+               ).unwrap();
+               let path = route.paths[0].iter().map(|hop| hop.short_channel_id).collect::<Vec<_>>();
+
+               assert_eq!(route.get_total_fees(), 300);
+               assert_eq!(route.get_total_amount(), 100);
+               assert_eq!(path, vec![2, 4, 7, 10]);
+       }
+
+       struct BadChannelScorer {
+               short_channel_id: u64,
+       }
+
+       #[cfg(c_bindings)]
+       impl Writeable for BadChannelScorer {
+               fn write<W: Writer>(&self, _w: &mut W) -> Result<(), ::io::Error> { unimplemented!() }
+       }
+       impl Score for BadChannelScorer {
+               fn channel_penalty_msat(&self, short_channel_id: u64, _send_amt: u64, _chan_amt: Option<u64>, _source: &NodeId, _target: &NodeId) -> u64 {
+                       if short_channel_id == self.short_channel_id { u64::max_value() } else { 0 }
+               }
+
+               fn payment_path_failed(&mut self, _path: &[&RouteHop], _short_channel_id: u64) {}
+               fn payment_path_successful(&mut self, _path: &[&RouteHop]) {}
+       }
+
+       struct BadNodeScorer {
+               node_id: NodeId,
+       }
+
+       #[cfg(c_bindings)]
+       impl Writeable for BadNodeScorer {
+               fn write<W: Writer>(&self, _w: &mut W) -> Result<(), ::io::Error> { unimplemented!() }
+       }
+
+       impl Score for BadNodeScorer {
+               fn channel_penalty_msat(&self, _short_channel_id: u64, _send_amt: u64, _chan_amt: Option<u64>, _source: &NodeId, target: &NodeId) -> u64 {
+                       if *target == self.node_id { u64::max_value() } else { 0 }
+               }
+
+               fn payment_path_failed(&mut self, _path: &[&RouteHop], _short_channel_id: u64) {}
+               fn payment_path_successful(&mut self, _path: &[&RouteHop]) {}
+       }
+
+       #[test]
+       fn avoids_routing_through_bad_channels_and_nodes() {
+               let (secp_ctx, network_graph, _, _, logger) = build_graph();
+               let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
+               let payee = Payee::from_node_id(nodes[6]).with_route_hints(last_hops(&nodes));
+
+               // A path to nodes[6] exists when no penalties are applied to any channel.
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
+               let route = get_route(
+                       &our_id, &payee, &network_graph, None, 100, 42,
+                       Arc::clone(&logger), &scorer
+               ).unwrap();
+               let path = route.paths[0].iter().map(|hop| hop.short_channel_id).collect::<Vec<_>>();
+
+               assert_eq!(route.get_total_fees(), 100);
+               assert_eq!(route.get_total_amount(), 100);
+               assert_eq!(path, vec![2, 4, 6, 11, 8]);
+
+               // A different path to nodes[6] exists if channel 6 cannot be routed over.
+               let scorer = BadChannelScorer { short_channel_id: 6 };
+               let route = get_route(
+                       &our_id, &payee, &network_graph, None, 100, 42,
+                       Arc::clone(&logger), &scorer
+               ).unwrap();
+               let path = route.paths[0].iter().map(|hop| hop.short_channel_id).collect::<Vec<_>>();
+
+               assert_eq!(route.get_total_fees(), 300);
+               assert_eq!(route.get_total_amount(), 100);
+               assert_eq!(path, vec![2, 4, 7, 10]);
+
+               // A path to nodes[6] does not exist if nodes[2] cannot be routed through.
+               let scorer = BadNodeScorer { node_id: NodeId::from_pubkey(&nodes[2]) };
+               match get_route(
+                       &our_id, &payee, &network_graph, None, 100, 42,
+                       Arc::clone(&logger), &scorer
+               ) {
+                       Err(LightningError { err, .. } ) => {
+                               assert_eq!(err, "Failed to find a path to the given destination");
+                       },
+                       Ok(_) => panic!("Expected error"),
+               }
+       }
+
+       #[test]
+       fn total_fees_single_path() {
+               let route = Route {
+                       paths: vec![vec![
+                               RouteHop {
+                                       pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
+                                       channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
+                                       short_channel_id: 0, fee_msat: 100, cltv_expiry_delta: 0
+                               },
+                               RouteHop {
+                                       pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
+                                       channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
+                                       short_channel_id: 0, fee_msat: 150, cltv_expiry_delta: 0
+                               },
+                               RouteHop {
+                                       pubkey: PublicKey::from_slice(&hex::decode("027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007").unwrap()[..]).unwrap(),
+                                       channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
+                                       short_channel_id: 0, fee_msat: 225, cltv_expiry_delta: 0
+                               },
+                       ]],
+                       payee: None,
+               };
+
+               assert_eq!(route.get_total_fees(), 250);
+               assert_eq!(route.get_total_amount(), 225);
+       }
+
+       #[test]
+       fn total_fees_multi_path() {
+               let route = Route {
+                       paths: vec![vec![
+                               RouteHop {
+                                       pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
+                                       channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
+                                       short_channel_id: 0, fee_msat: 100, cltv_expiry_delta: 0
+                               },
+                               RouteHop {
+                                       pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
+                                       channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
+                                       short_channel_id: 0, fee_msat: 150, cltv_expiry_delta: 0
+                               },
+                       ],vec![
+                               RouteHop {
+                                       pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
+                                       channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
+                                       short_channel_id: 0, fee_msat: 100, cltv_expiry_delta: 0
+                               },
+                               RouteHop {
+                                       pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
+                                       channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
+                                       short_channel_id: 0, fee_msat: 150, cltv_expiry_delta: 0
+                               },
+                       ]],
+                       payee: None,
+               };
+
+               assert_eq!(route.get_total_fees(), 200);
+               assert_eq!(route.get_total_amount(), 300);
+       }
+
+       #[test]
+       fn total_empty_route_no_panic() {
+               // In an earlier version of `Route::get_total_fees` and `Route::get_total_amount`, they
+               // would both panic if the route was completely empty. We test to ensure they return 0
+               // here, even though its somewhat nonsensical as a route.
+               let route = Route { paths: Vec::new(), payee: None };
+
+               assert_eq!(route.get_total_fees(), 0);
+               assert_eq!(route.get_total_amount(), 0);
+       }
+
+       #[cfg(not(feature = "no-std"))]
+       pub(super) fn random_init_seed() -> u64 {
+               // Because the default HashMap in std pulls OS randomness, we can use it as a (bad) RNG.
+               use core::hash::{BuildHasher, Hasher};
+               let seed = std::collections::hash_map::RandomState::new().build_hasher().finish();
+               println!("Using seed of {}", seed);
+               seed
+       }
+       #[cfg(not(feature = "no-std"))]
+       use util::ser::Readable;
+
+       #[test]
+       #[cfg(not(feature = "no-std"))]
+       fn generate_routes() {
+               let mut d = match super::test_utils::get_route_file() {
+                       Ok(f) => f,
+                       Err(e) => {
+                               eprintln!("{}", e);
+                               return;
+                       },
+               };
+               let graph = NetworkGraph::read(&mut d).unwrap();
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
+
+               // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
+               let mut seed = random_init_seed() as usize;
+               let nodes = graph.read_only().nodes().clone();
+               'load_endpoints: for _ in 0..10 {
+                       loop {
+                               seed = seed.overflowing_mul(0xdeadbeef).0;
+                               let src = &PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
+                               seed = seed.overflowing_mul(0xdeadbeef).0;
+                               let dst = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
+                               let payee = Payee::from_node_id(dst);
+                               let amt = seed as u64 % 200_000_000;
+                               if get_route(src, &payee, &graph, None, amt, 42, &test_utils::TestLogger::new(), &scorer).is_ok() {
+                                       continue 'load_endpoints;
+                               }
+                       }
+               }
+       }
+
+       #[test]
+       #[cfg(not(feature = "no-std"))]
+       fn generate_routes_mpp() {
+               let mut d = match super::test_utils::get_route_file() {
+                       Ok(f) => f,
+                       Err(e) => {
+                               eprintln!("{}", e);
+                               return;
+                       },
+               };
+               let graph = NetworkGraph::read(&mut d).unwrap();
+               let scorer = test_utils::TestScorer::with_fixed_penalty(0);
+
+               // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
+               let mut seed = random_init_seed() as usize;
+               let nodes = graph.read_only().nodes().clone();
+               'load_endpoints: for _ in 0..10 {
+                       loop {
+                               seed = seed.overflowing_mul(0xdeadbeef).0;
+                               let src = &PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
+                               seed = seed.overflowing_mul(0xdeadbeef).0;
+                               let dst = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
+                               let payee = Payee::from_node_id(dst).with_features(InvoiceFeatures::known());
+                               let amt = seed as u64 % 200_000_000;
+                               if get_route(src, &payee, &graph, None, amt, 42, &test_utils::TestLogger::new(), &scorer).is_ok() {
+                                       continue 'load_endpoints;
+                               }
+                       }
+               }
+       }
 }
 
-#[cfg(all(test, feature = "unstable"))]
+#[cfg(all(test, not(feature = "no-std")))]
+pub(crate) mod test_utils {
+       use std::fs::File;
+       /// Tries to open a network graph file, or panics with a URL to fetch it.
+       pub(crate) fn get_route_file() -> Result<std::fs::File, &'static str> {
+               let res = File::open("net_graph-2021-05-31.bin") // By default we're run in RL/lightning
+                       .or_else(|_| File::open("lightning/net_graph-2021-05-31.bin")) // We may be run manually in RL/
+                       .or_else(|_| { // Fall back to guessing based on the binary location
+                               // path is likely something like .../rust-lightning/target/debug/deps/lightning-...
+                               let mut path = std::env::current_exe().unwrap();
+                               path.pop(); // lightning-...
+                               path.pop(); // deps
+                               path.pop(); // debug
+                               path.pop(); // target
+                               path.push("lightning");
+                               path.push("net_graph-2021-05-31.bin");
+                               eprintln!("{}", path.to_str().unwrap());
+                               File::open(path)
+                       })
+               .map_err(|_| "Please fetch https://bitcoin.ninja/ldk-net_graph-v0.0.15-2021-05-31.bin and place it at lightning/net_graph-2021-05-31.bin");
+               #[cfg(require_route_graph_test)]
+               return Ok(res.unwrap());
+               #[cfg(not(require_route_graph_test))]
+               return res;
+       }
+}
+
+#[cfg(all(test, feature = "unstable", not(feature = "no-std")))]
 mod benches {
        use super::*;
+       use routing::scoring::Scorer;
        use util::logger::{Logger, Record};
 
-       use std::fs::File;
        use test::Bencher;
 
        struct DummyLogger {}
@@ -3762,8 +4917,10 @@ mod benches {
 
        #[bench]
        fn generate_routes(bench: &mut Bencher) {
-               let mut d = File::open("net_graph-2021-02-12.bin").expect("Please fetch https://bitcoin.ninja/ldk-net_graph-879e309c128-2020-02-12.bin and place it at lightning/net_graph-2021-02-12.bin");
+               let mut d = test_utils::get_route_file().unwrap();
                let graph = NetworkGraph::read(&mut d).unwrap();
+               let nodes = graph.read_only().nodes().clone();
+               let scorer = Scorer::with_fixed_penalty(0);
 
                // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
                let mut path_endpoints = Vec::new();
@@ -3771,11 +4928,12 @@ mod benches {
                'load_endpoints: for _ in 0..100 {
                        loop {
                                seed *= 0xdeadbeef;
-                               let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
+                               let src = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
                                seed *= 0xdeadbeef;
-                               let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
+                               let dst = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
+                               let payee = Payee::from_node_id(dst);
                                let amt = seed as u64 % 1_000_000;
-                               if get_route(src, &graph, dst, None, None, &[], amt, 42, &DummyLogger{}).is_ok() {
+                               if get_route(&src, &payee, &graph, None, amt, 42, &DummyLogger{}, &scorer).is_ok() {
                                        path_endpoints.push((src, dst, amt));
                                        continue 'load_endpoints;
                                }
@@ -3786,15 +4944,18 @@ mod benches {
                let mut idx = 0;
                bench.iter(|| {
                        let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
-                       assert!(get_route(src, &graph, dst, None, None, &[], amt, 42, &DummyLogger{}).is_ok());
+                       let payee = Payee::from_node_id(dst);
+                       assert!(get_route(&src, &payee, &graph, None, amt, 42, &DummyLogger{}, &scorer).is_ok());
                        idx += 1;
                });
        }
 
        #[bench]
        fn generate_mpp_routes(bench: &mut Bencher) {
-               let mut d = File::open("net_graph-2021-02-12.bin").expect("Please fetch https://bitcoin.ninja/ldk-net_graph-879e309c128-2020-02-12.bin and place it at lightning/net_graph-2021-02-12.bin");
+               let mut d = test_utils::get_route_file().unwrap();
                let graph = NetworkGraph::read(&mut d).unwrap();
+               let nodes = graph.read_only().nodes().clone();
+               let scorer = Scorer::with_fixed_penalty(0);
 
                // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
                let mut path_endpoints = Vec::new();
@@ -3802,11 +4963,12 @@ mod benches {
                'load_endpoints: for _ in 0..100 {
                        loop {
                                seed *= 0xdeadbeef;
-                               let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
+                               let src = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
                                seed *= 0xdeadbeef;
-                               let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
+                               let dst = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
+                               let payee = Payee::from_node_id(dst).with_features(InvoiceFeatures::known());
                                let amt = seed as u64 % 1_000_000;
-                               if get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &DummyLogger{}).is_ok() {
+                               if get_route(&src, &payee, &graph, None, amt, 42, &DummyLogger{}, &scorer).is_ok() {
                                        path_endpoints.push((src, dst, amt));
                                        continue 'load_endpoints;
                                }
@@ -3817,7 +4979,8 @@ mod benches {
                let mut idx = 0;
                bench.iter(|| {
                        let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
-                       assert!(get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &DummyLogger{}).is_ok());
+                       let payee = Payee::from_node_id(dst).with_features(InvoiceFeatures::known());
+                       assert!(get_route(&src, &payee, &graph, None, amt, 42, &DummyLogger{}, &scorer).is_ok());
                        idx += 1;
                });
        }