]> git.bitcoin.ninja Git - rust-lightning/commitdiff
Effective channel capacity for router and scoring
authorJeffrey Czyz <jkczyz@gmail.com>
Wed, 29 Dec 2021 15:56:54 +0000 (09:56 -0600)
committerJeffrey Czyz <jkczyz@gmail.com>
Thu, 20 Jan 2022 22:14:31 +0000 (16:14 -0600)
A channel's capacity may be inferred or learned and is used to make
routing decisions, including as a parameter to channel scoring. Define
an EffectiveCapacity for this purpose. Score::channel_penalty_msat takes
the effective capacity (less in-flight HTLCs for the same payment), and
never None. Thus, for hops given in an invoice, the effective capacity
is now considered (near) infinite if over a private channel or based on
learned information if over a public channel.

If a Score implementations needs the effective capacity when updating a
channel's score, i.e. in payment_path_failed or payment_path_successful,
it can access the channel's EffectiveCapacity via the NetworkGraph by
first looking up the channel and then specifying which direction is
desired using ChannelInfo::as_directed.

lightning-invoice/src/payment.rs
lightning/src/routing/network_graph.rs
lightning/src/routing/router.rs
lightning/src/routing/scoring.rs

index d73ca538981d9e203d2614f68acab93e1a6caf46..b869d18976007226ffca5194514b1c85c7eb4839 100644 (file)
@@ -90,7 +90,7 @@
 //! # }
 //! # impl Score for FakeScorer {
 //! #     fn channel_penalty_msat(
-//! #         &self, _short_channel_id: u64, _send_amt: u64, _chan_amt: Option<u64>, _source: &NodeId, _target: &NodeId
+//! #         &self, _short_channel_id: u64, _send_amt: u64, _chan_amt: u64, _source: &NodeId, _target: &NodeId
 //! #     ) -> u64 { 0 }
 //! #     fn payment_path_failed(&mut self, _path: &[&RouteHop], _short_channel_id: u64) {}
 //! #     fn payment_path_successful(&mut self, _path: &[&RouteHop]) {}
@@ -1327,7 +1327,7 @@ mod tests {
 
        impl Score for TestScorer {
                fn channel_penalty_msat(
-                       &self, _short_channel_id: u64, _send_amt: u64, _chan_amt: Option<u64>, _source: &NodeId, _target: &NodeId
+                       &self, _short_channel_id: u64, _send_amt: u64, _chan_amt: u64, _source: &NodeId, _target: &NodeId
                ) -> u64 { 0 }
 
                fn payment_path_failed(&mut self, actual_path: &[&RouteHop], actual_short_channel_id: u64) {
index a26b549b43d45de4d96cc91ddf3d32921c241f3b..e3ce80138763d91caa083b76ede83f64310f3ff6 100644 (file)
@@ -593,9 +593,8 @@ where
 }
 
 #[derive(Clone, Debug, PartialEq)]
-/// Details about one direction of a channel. Received
-/// within a channel update.
-pub struct DirectionalChannelInfo {
+/// Details about one direction of a channel as received within a [`ChannelUpdate`].
+pub struct ChannelUpdateInfo {
        /// When the last update to the channel direction was issued.
        /// Value is opaque, as set in the announcement.
        pub last_update: u32,
@@ -616,14 +615,14 @@ pub struct DirectionalChannelInfo {
        pub last_update_message: Option<ChannelUpdate>,
 }
 
-impl fmt::Display for DirectionalChannelInfo {
+impl fmt::Display for ChannelUpdateInfo {
        fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
                write!(f, "last_update {}, enabled {}, cltv_expiry_delta {}, htlc_minimum_msat {}, fees {:?}", self.last_update, self.enabled, self.cltv_expiry_delta, self.htlc_minimum_msat, self.fees)?;
                Ok(())
        }
 }
 
-impl_writeable_tlv_based!(DirectionalChannelInfo, {
+impl_writeable_tlv_based!(ChannelUpdateInfo, {
        (0, last_update, required),
        (2, enabled, required),
        (4, cltv_expiry_delta, required),
@@ -642,11 +641,11 @@ pub struct ChannelInfo {
        /// Source node of the first direction of a channel
        pub node_one: NodeId,
        /// Details about the first direction of a channel
-       pub one_to_two: Option<DirectionalChannelInfo>,
+       pub one_to_two: Option<ChannelUpdateInfo>,
        /// Source node of the second direction of a channel
        pub node_two: NodeId,
        /// Details about the second direction of a channel
-       pub two_to_one: Option<DirectionalChannelInfo>,
+       pub two_to_one: Option<ChannelUpdateInfo>,
        /// The channel capacity as seen on-chain, if chain lookup is available.
        pub capacity_sats: Option<u64>,
        /// An initial announcement of the channel
@@ -660,6 +659,23 @@ pub struct ChannelInfo {
        announcement_received_time: u64,
 }
 
+impl ChannelInfo {
+       /// Returns a [`DirectedChannelInfo`] for the channel directed to the given `target`, or `None`
+       /// if `target` is not one of the channel's counterparties.
+       pub fn as_directed_to(&self, target: &NodeId) -> Option<DirectedChannelInfo> {
+               let (direction, source, target) = {
+                       if target == &self.node_one {
+                               (self.two_to_one.as_ref(), &self.node_two, &self.node_one)
+                       } else if target == &self.node_two {
+                               (self.one_to_two.as_ref(), &self.node_one, &self.node_two)
+                       } else {
+                               return None;
+                       }
+               };
+               Some(DirectedChannelInfo { channel: self, direction, source, target })
+       }
+}
+
 impl fmt::Display for ChannelInfo {
        fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
                write!(f, "features: {}, node_one: {}, one_to_two: {:?}, node_two: {}, two_to_one: {:?}",
@@ -679,6 +695,98 @@ impl_writeable_tlv_based!(ChannelInfo, {
        (12, announcement_message, required),
 });
 
+/// A wrapper around [`ChannelInfo`] representing information about the channel as directed from a
+/// source node to a target node.
+#[derive(Clone, Debug)]
+pub struct DirectedChannelInfo<'a: 'b, 'b> {
+       channel: &'a ChannelInfo,
+       direction: Option<&'b ChannelUpdateInfo>,
+       source: &'b NodeId,
+       target: &'b NodeId,
+}
+
+impl<'a: 'b, 'b> DirectedChannelInfo<'a, 'b> {
+       /// Returns information for the channel.
+       pub fn channel(&self) -> &'a ChannelInfo { self.channel }
+
+       /// Returns information for the direction.
+       pub fn direction(&self) -> Option<&'b ChannelUpdateInfo> { self.direction }
+
+       /// Returns the node id for the source.
+       pub fn source(&self) -> &'b NodeId { self.source }
+
+       /// Returns the node id for the target.
+       pub fn target(&self) -> &'b NodeId { self.target }
+
+       /// Returns the [`EffectiveCapacity`] of the channel in a specific direction.
+       ///
+       /// This is either the total capacity from the funding transaction, if known, or the
+       /// `htlc_maximum_msat` for the direction as advertised by the gossip network, if known,
+       /// whichever is smaller.
+       pub fn effective_capacity(&self) -> EffectiveCapacity {
+               let capacity_msat = self.channel.capacity_sats.map(|capacity_sats| capacity_sats * 1000);
+               self.direction
+                       .and_then(|direction| direction.htlc_maximum_msat)
+                       .map(|max_htlc_msat| {
+                               let capacity_msat = capacity_msat.unwrap_or(u64::max_value());
+                               if max_htlc_msat < capacity_msat {
+                                       EffectiveCapacity::MaximumHTLC { amount_msat: max_htlc_msat }
+                               } else {
+                                       EffectiveCapacity::Total { capacity_msat }
+                               }
+                       })
+                       .or_else(|| capacity_msat.map(|capacity_msat|
+                                       EffectiveCapacity::Total { capacity_msat }))
+                       .unwrap_or(EffectiveCapacity::Unknown)
+       }
+}
+
+/// The effective capacity of a channel for routing purposes.
+///
+/// While this may be smaller than the actual channel capacity, amounts greater than
+/// [`Self::as_msat`] should not be routed through the channel.
+pub enum EffectiveCapacity {
+       /// The available liquidity in the channel known from being a channel counterparty, and thus a
+       /// direct hop.
+       ExactLiquidity {
+               /// Either the inbound or outbound liquidity depending on the direction, denominated in
+               /// millisatoshi.
+               liquidity_msat: u64,
+       },
+       /// The maximum HTLC amount in one direction as advertised on the gossip network.
+       MaximumHTLC {
+               /// The maximum HTLC amount denominated in millisatoshi.
+               amount_msat: u64,
+       },
+       /// The total capacity of the channel as determined by the funding transaction.
+       Total {
+               /// The funding amount denominated in millisatoshi.
+               capacity_msat: u64,
+       },
+       /// A capacity sufficient to route any payment, typically used for private channels provided by
+       /// an invoice, though may not be the case for zero-amount invoices.
+       Infinite,
+       /// A capacity that is unknown possibly because either the chain state is unavailable to know
+       /// the total capacity or the `htlc_maximum_msat` was not advertised on the gossip network.
+       Unknown,
+}
+
+/// The presumed channel capacity denominated in millisatoshi for [`EffectiveCapacity::Unknown`] to
+/// use when making routing decisions.
+pub const UNKNOWN_CHANNEL_CAPACITY_MSAT: u64 = 250_000 * 1000;
+
+impl EffectiveCapacity {
+       /// Returns the effective capacity denominated in millisatoshi.
+       pub fn as_msat(&self) -> u64 {
+               match self {
+                       EffectiveCapacity::ExactLiquidity { liquidity_msat } => *liquidity_msat,
+                       EffectiveCapacity::MaximumHTLC { amount_msat } => *amount_msat,
+                       EffectiveCapacity::Total { capacity_msat } => *capacity_msat,
+                       EffectiveCapacity::Infinite => u64::max_value(),
+                       EffectiveCapacity::Unknown => UNKNOWN_CHANNEL_CAPACITY_MSAT,
+               }
+       }
+}
 
 /// Fees for routing via a given channel or a node
 #[derive(Eq, PartialEq, Copy, Clone, Debug, Hash)]
@@ -1227,7 +1335,7 @@ impl NetworkGraph {
                                                let last_update_message = if msg.excess_data.len() <= MAX_EXCESS_BYTES_FOR_RELAY
                                                        { full_msg.cloned() } else { None };
 
-                                               let updated_channel_dir_info = DirectionalChannelInfo {
+                                               let updated_channel_update_info = ChannelUpdateInfo {
                                                        enabled: chan_enabled,
                                                        last_update: msg.timestamp,
                                                        cltv_expiry_delta: msg.cltv_expiry_delta,
@@ -1239,7 +1347,7 @@ impl NetworkGraph {
                                                        },
                                                        last_update_message
                                                };
-                                               $target = Some(updated_channel_dir_info);
+                                               $target = Some(updated_channel_update_info);
                                        }
                                }
 
index 2ddc4f5db461f445d3d6d2233671de47d7919a6c..c777bfd3dcc84b257429ef9c5bcc5213d008f9ac 100644 (file)
@@ -18,7 +18,7 @@ use ln::channelmanager::ChannelDetails;
 use ln::features::{ChannelFeatures, InvoiceFeatures, NodeFeatures};
 use ln::msgs::{DecodeError, ErrorAction, LightningError, MAX_VALUE_MSAT};
 use routing::scoring::Score;
-use routing::network_graph::{NetworkGraph, NodeId, RoutingFees};
+use routing::network_graph::{DirectedChannelInfo, EffectiveCapacity, NetworkGraph, NodeId, RoutingFees};
 use util::ser::{Writeable, Readable};
 use util::logger::{Level, Logger};
 
@@ -344,11 +344,83 @@ impl cmp::PartialOrd for RouteGraphNode {
        }
 }
 
-struct DummyDirectionalChannelInfo {
-       cltv_expiry_delta: u32,
-       htlc_minimum_msat: u64,
-       htlc_maximum_msat: Option<u64>,
-       fees: RoutingFees,
+/// A wrapper around the various hop representations.
+///
+/// Used to construct a [`PathBuildingHop`] and to estimate [`EffectiveCapacity`].
+#[derive(Clone, Debug)]
+enum CandidateRouteHop<'a> {
+       /// A hop from the payer to the next hop to the payee, where the outbound liquidity is known.
+       FirstHop {
+               details: &'a ChannelDetails,
+       },
+       /// A hop found in the [`NetworkGraph`], where the channel capacity may or may not be known.
+       PublicHop {
+               // `DirectedChannelInfo::direction` MUST NOT be `None`.
+               info: DirectedChannelInfo<'a, 'a>,
+               short_channel_id: u64,
+       },
+       /// A hop to the payee found in the payment invoice, though not necessarily a direct channel.
+       PrivateHop {
+               hint: &'a RouteHintHop,
+       }
+}
+
+impl<'a> CandidateRouteHop<'a> {
+       fn short_channel_id(&self) -> u64 {
+               match self {
+                       CandidateRouteHop::FirstHop { details } => details.short_channel_id.unwrap(),
+                       CandidateRouteHop::PublicHop { short_channel_id, .. } => *short_channel_id,
+                       CandidateRouteHop::PrivateHop { hint } => hint.short_channel_id,
+               }
+       }
+
+       fn features(&self) -> ChannelFeatures {
+               match self {
+                       CandidateRouteHop::FirstHop { details } => details.counterparty.features.to_context(),
+                       CandidateRouteHop::PublicHop { info, .. } => info.channel().features.clone(),
+                       CandidateRouteHop::PrivateHop { .. } => ChannelFeatures::empty(),
+               }
+       }
+
+       fn cltv_expiry_delta(&self) -> u32 {
+               match self {
+                       CandidateRouteHop::FirstHop { .. } => 0,
+                       CandidateRouteHop::PublicHop { info, .. } => {
+                               info.direction().unwrap().cltv_expiry_delta as u32
+                       },
+                       CandidateRouteHop::PrivateHop { hint } => hint.cltv_expiry_delta as u32,
+               }
+       }
+
+       fn htlc_minimum_msat(&self) -> u64 {
+               match self {
+                       CandidateRouteHop::FirstHop { .. } => 0,
+                       CandidateRouteHop::PublicHop { info, .. } => {
+                               info.direction().unwrap().htlc_minimum_msat
+                       },
+                       CandidateRouteHop::PrivateHop { hint } => hint.htlc_minimum_msat.unwrap_or(0),
+               }
+       }
+
+       fn fees(&self) -> RoutingFees {
+               match self {
+                       CandidateRouteHop::FirstHop { .. } => RoutingFees {
+                               base_msat: 0, proportional_millionths: 0,
+                       },
+                       CandidateRouteHop::PublicHop { info, .. } => info.direction().unwrap().fees,
+                       CandidateRouteHop::PrivateHop { hint } => hint.fees,
+               }
+       }
+
+       fn effective_capacity(&self) -> EffectiveCapacity {
+               match self {
+                       CandidateRouteHop::FirstHop { details } => EffectiveCapacity::ExactLiquidity {
+                               liquidity_msat: details.outbound_capacity_msat,
+                       },
+                       CandidateRouteHop::PublicHop { info, .. } => info.effective_capacity(),
+                       CandidateRouteHop::PrivateHop { .. } => EffectiveCapacity::Infinite,
+               }
+       }
 }
 
 /// It's useful to keep track of the hops associated with the fees required to use them,
@@ -357,21 +429,17 @@ struct DummyDirectionalChannelInfo {
 /// These fee values are useful to choose hops as we traverse the graph "payee-to-payer".
 #[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.
+       // Note that this should be dropped in favor of loading it from CandidateRouteHop, but doing so
+       // is a larger refactor and will require careful performance analysis.
        node_id: NodeId,
-       short_channel_id: u64,
-       channel_features: &'a ChannelFeatures,
+       candidate: CandidateRouteHop<'a>,
        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.
-       channel_fees: RoutingFees,
        /// All the fees paid *after* this channel on the way to the destination
        next_hops_fee_msat: u64,
-       /// Fee paid for the use of the current channel (see channel_fees).
+       /// Fee paid for the use of the current channel (see candidate.fees()).
        /// The value will be actually deducted from the counterparty balance on the previous link.
        hop_use_fee_msat: u64,
        /// Used to compare channels when choosing the for routing.
@@ -379,10 +447,6 @@ struct PathBuildingHop<'a> {
        /// an estimated cost of reaching this hop.
        /// Might get stale when fees are recomputed. Primarily for internal use.
        total_fee_msat: u64,
-       /// This is useful for update_value_and_recompute_fees to make sure
-       /// we don't fall below the minimum. Should not be updated manually and
-       /// generally should not be accessed.
-       htlc_minimum_msat: u64,
        /// 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,
@@ -461,7 +525,7 @@ impl<'a> PaymentPath<'a> {
                        // set it too high just to maliciously take more fees by exploiting this
                        // match htlc_minimum_msat logic.
                        let mut cur_hop_transferred_amount_msat = total_fee_paid_msat + value_msat;
-                       if let Some(extra_fees_msat) = cur_hop.htlc_minimum_msat.checked_sub(cur_hop_transferred_amount_msat) {
+                       if let Some(extra_fees_msat) = cur_hop.candidate.htlc_minimum_msat().checked_sub(cur_hop_transferred_amount_msat) {
                                // Note that there is a risk that *previous hops* (those closer to us, as we go
                                // payee->our_node here) would exceed their htlc_maximum_msat or available balance.
                                //
@@ -489,7 +553,7 @@ impl<'a> PaymentPath<'a> {
                        // Irrelevant for the first hop, as it doesn't have the previous hop, and the use of
                        // this channel is free for us.
                        if i != 0 {
-                               if let Some(new_fee) = compute_fees(cur_hop_transferred_amount_msat, cur_hop.channel_fees) {
+                               if let Some(new_fee) = compute_fees(cur_hop_transferred_amount_msat, cur_hop.candidate.fees()) {
                                        cur_hop.hop_use_fee_msat = new_fee;
                                        total_fee_paid_msat += new_fee;
                                } else {
@@ -648,15 +712,6 @@ where L::Target: Logger {
        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,
-               htlc_maximum_msat: None,
-               fees: RoutingFees {
-                       base_msat: 0,
-                       proportional_millionths: 0,
-               }
-       };
 
        // 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
@@ -675,24 +730,26 @@ where L::Target: Logger {
        // 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<_, Vec<(_, ChannelFeatures, _, NodeFeatures)>> =
+       let mut first_hop_targets: HashMap<_, Vec<&ChannelDetails>> =
                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.short_channel_id.is_none() {
+                               panic!("first_hops should be filled in with usable channels, not pending ones");
+                       }
                        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.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()));
+                       first_hop_targets
+                               .entry(NodeId::from_pubkey(&chan.counterparty.node_id))
+                               .or_insert(Vec::new())
+                               .push(chan);
                }
                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.
@@ -731,42 +788,24 @@ where L::Target: Logger {
        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.
+               // Adds entry which goes from $src_node_id to $dest_node_id over the $candidate hop.
                // $next_hops_fee_msat represents the fees paid for using all the channels *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_path_penalty_msat: expr, $next_hops_cltv_delta: expr ) => { {
+               ( $candidate: expr, $src_node_id: expr, $dest_node_id: expr, $next_hops_fee_msat: expr,
+                  $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr,
+                  $next_hops_path_penalty_msat: expr, $next_hops_cltv_delta: expr ) => { {
                        // 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)
                        // - for first and last hops early in get_route
-                       if $src_node_id != $dest_node_id.clone() {
-                               let available_liquidity_msat = bookkept_channels_liquidity_available_msat.entry($chan_id.clone()).or_insert_with(|| {
-                                       let mut initial_liquidity_available_msat = None;
-                                       if let Some(capacity_sats) = $capacity_sats {
-                                               initial_liquidity_available_msat = Some(capacity_sats * 1000);
-                                       }
-
-                                       if let Some(htlc_maximum_msat) = $directional_info.htlc_maximum_msat {
-                                               if let Some(available_msat) = initial_liquidity_available_msat {
-                                                       initial_liquidity_available_msat = Some(cmp::min(available_msat, htlc_maximum_msat));
-                                               } else {
-                                                       initial_liquidity_available_msat = Some(htlc_maximum_msat);
-                                               }
-                                       }
-
-                                       match initial_liquidity_available_msat {
-                                               Some(available_msat) => available_msat,
-                                               // We assume channels with unknown balance have
-                                               // a capacity of 0.0025 BTC (or 250_000 sats).
-                                               None => 250_000 * 1000
-                                       }
-                               });
+                       if $src_node_id != $dest_node_id {
+                               let short_channel_id = $candidate.short_channel_id();
+                               let available_liquidity_msat = bookkept_channels_liquidity_available_msat
+                                       .entry(short_channel_id)
+                                       .or_insert_with(|| $candidate.effective_capacity().as_msat());
 
                                // It is tricky to substract $next_hops_fee_msat from available liquidity here.
                                // It may be misleading because we might later choose to reduce the value transferred
@@ -800,11 +839,10 @@ where L::Target: Logger {
                                        // Verify the liquidity offered by this channel complies to the minimal contribution.
                                        let contributes_sufficient_value = available_value_contribution_msat >= minimal_value_contribution_msat;
 
-
                                        // Do not consider candidates that exceed the maximum total cltv expiry limit.
                                        let max_total_cltv_expiry_delta = payee.max_total_cltv_expiry_delta;
                                        let hop_total_cltv_delta = ($next_hops_cltv_delta as u32)
-                                               .checked_add($directional_info.cltv_expiry_delta as u32)
+                                               .checked_add($candidate.cltv_expiry_delta())
                                                .unwrap_or(u32::max_value());
                                        let doesnt_exceed_cltv_delta_limit = hop_total_cltv_delta <= max_total_cltv_expiry_delta;
 
@@ -816,7 +854,7 @@ where L::Target: Logger {
                                                None => unreachable!(),
                                        };
                                        #[allow(unused_comparisons)] // $next_hops_path_htlc_minimum_msat is 0 in some calls so rustc complains
-                                       let over_path_minimum_msat = amount_to_transfer_over_msat >= $directional_info.htlc_minimum_msat &&
+                                       let over_path_minimum_msat = amount_to_transfer_over_msat >= $candidate.htlc_minimum_msat() &&
                                                amount_to_transfer_over_msat >= $next_hops_path_htlc_minimum_msat;
 
                                        // If HTLC minimum is larger than the amount we're going to transfer, we shouldn't
@@ -831,16 +869,16 @@ where L::Target: Logger {
                                                // 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 fees knowing the final path contribution after constructing it.
-                                               let path_htlc_minimum_msat = compute_fees($next_hops_path_htlc_minimum_msat, $directional_info.fees)
+                                               let path_htlc_minimum_msat = compute_fees($next_hops_path_htlc_minimum_msat, $candidate.fees())
                                                        .and_then(|fee_msat| fee_msat.checked_add($next_hops_path_htlc_minimum_msat))
-                                                       .map(|fee_msat| cmp::max(fee_msat, $directional_info.htlc_minimum_msat))
+                                                       .map(|fee_msat| cmp::max(fee_msat, $candidate.htlc_minimum_msat()))
                                                        .unwrap_or_else(|| u64::max_value());
                                                let hm_entry = dist.entry($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
-                                                       // semi-dummy record just to compute the fees to reach the source node.
-                                                       // This will affect our decision on selecting $chan_id
+                                                       // If there was previously no known way to access the source node
+                                                       // (recall it goes payee-to-payer) of short_channel_id, first add a
+                                                       // semi-dummy record just to compute the fees to reach the source node.
+                                                       // This will affect our decision on selecting short_channel_id
                                                        // 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();
@@ -850,19 +888,15 @@ where L::Target: Logger {
                                                        }
                                                        PathBuildingHop {
                                                                node_id: $dest_node_id.clone(),
-                                                               short_channel_id: 0,
-                                                               channel_features: $chan_features,
+                                                               candidate: $candidate.clone(),
                                                                fee_msat: 0,
-                                                               cltv_expiry_delta: 0,
                                                                src_lowest_inbound_fees: RoutingFees {
                                                                        base_msat: fee_base_msat,
                                                                        proportional_millionths: fee_proportional_millionths,
                                                                },
-                                                               channel_fees: $directional_info.fees,
                                                                next_hops_fee_msat: u64::max_value(),
                                                                hop_use_fee_msat: u64::max_value(),
                                                                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,
@@ -887,7 +921,7 @@ where L::Target: Logger {
                                                        // 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) {
+                                                               match compute_fees(amount_to_transfer_over_msat, $candidate.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(),
@@ -917,7 +951,7 @@ where L::Target: Logger {
                                                        }
 
                                                        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),
+                                                               scorer.channel_penalty_msat(short_channel_id, amount_to_transfer_over_msat, *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,
@@ -929,7 +963,7 @@ where L::Target: Logger {
                                                                path_penalty_msat,
                                                        };
 
-                                                       // Update the way of reaching $src_node_id with the given $chan_id (from $dest_node_id),
+                                                       // Update the way of reaching $src_node_id with the given short_channel_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,
@@ -958,12 +992,8 @@ where L::Target: Logger {
                                                                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.candidate = $candidate.clone();
                                                                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"))]
@@ -1030,8 +1060,9 @@ where L::Target: Logger {
 
                        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, $next_hops_cltv_delta);
+                                       for details in first_channels {
+                                               let candidate = CandidateRouteHop::FirstHop { details };
+                                               add_entry!(candidate, our_node_id, $node_id, $fee_to_target_msat, $next_hops_value_contribution, $next_hops_path_htlc_minimum_msat, $next_hops_path_penalty_msat, $next_hops_cltv_delta);
                                        }
                                }
 
@@ -1045,21 +1076,18 @@ where L::Target: Logger {
                                        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, $next_hops_cltv_delta);
-                                                                               }
-                                                                       }
-                                                               }
-                                                       } 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, $next_hops_cltv_delta);
-                                                                               }
+                                                       let directed_channel =
+                                                               chan.as_directed_to(&$node_id).expect("inconsistent NetworkGraph");
+                                                       let source = directed_channel.source();
+                                                       let target = directed_channel.target();
+                                                       if first_hops.is_none() || *source != our_node_id {
+                                                               if let Some(direction) = directed_channel.direction() {
+                                                                       if direction.enabled {
+                                                                               let candidate = CandidateRouteHop::PublicHop {
+                                                                                       info: directed_channel,
+                                                                                       short_channel_id: *chan_id,
+                                                                               };
+                                                                               add_entry!(candidate, *source, *target, $fee_to_target_msat, $next_hops_value_contribution, $next_hops_path_htlc_minimum_msat, $next_hops_path_penalty_msat, $next_hops_cltv_delta);
                                                                        }
                                                                }
                                                        }
@@ -1084,9 +1112,10 @@ where L::Target: Logger {
                // 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 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, 0);
-                               log_trace!(logger, "{} direct route to payee via SCID {}", if added { "Added" } else { "Skipped" }, first_hop);
+                       for details in first_channels {
+                               let candidate = CandidateRouteHop::FirstHop { details };
+                               let added = add_entry!(candidate, our_node_id, payee_node_id, 0, path_value_msat, 0, 0u64, 0);
+                               log_trace!(logger, "{} direct route to payee via SCID {}", if added { "Added" } else { "Skipped" }, candidate.short_channel_id());
                        }
                }
 
@@ -1128,43 +1157,27 @@ where L::Target: Logger {
                                let mut aggregate_next_hops_cltv_delta: u32 = 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);
+                                       let source = NodeId::from_pubkey(&hop.src_node_id);
+                                       let target = NodeId::from_pubkey(&prev_hop_id);
+                                       let candidate = network_channels
+                                               .get(&hop.short_channel_id)
+                                               .and_then(|channel| channel.as_directed_to(&target))
+                                               .and_then(|channel| channel.direction().map(|_| channel))
+                                               .map(|info| CandidateRouteHop::PublicHop {
+                                                       info,
+                                                       short_channel_id: hop.short_channel_id,
+                                               })
+                                               .unwrap_or_else(|| CandidateRouteHop::PrivateHop { hint: hop });
+                                       let capacity_msat = candidate.effective_capacity().as_msat();
                                        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))
+                                               .checked_add(scorer.channel_penalty_msat(hop.short_channel_id, final_value_msat, capacity_msat, &source, &target))
                                                .unwrap_or_else(|| u64::max_value());
 
                                        aggregate_next_hops_cltv_delta = aggregate_next_hops_cltv_delta
                                                .checked_add(hop.cltv_expiry_delta as u32)
                                                .unwrap_or_else(|| u32::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, aggregate_next_hops_cltv_delta) {
+                                       if !add_entry!(candidate, source, target, aggregate_next_hops_fee_msat, path_value_msat, aggregate_next_hops_path_htlc_minimum_msat, aggregate_next_hops_path_penalty_msat, aggregate_next_hops_cltv_delta) {
                                                // 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
@@ -1173,8 +1186,9 @@ where L::Target: Logger {
 
                                        // 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, aggregate_next_hops_cltv_delta);
+                                               for details in first_channels {
+                                                       let candidate = CandidateRouteHop::FirstHop { details };
+                                                       add_entry!(candidate, our_node_id, NodeId::from_pubkey(&prev_hop_id), aggregate_next_hops_fee_msat, path_value_msat, aggregate_next_hops_path_htlc_minimum_msat, aggregate_next_hops_path_penalty_msat, aggregate_next_hops_cltv_delta);
                                                }
                                        }
 
@@ -1191,6 +1205,7 @@ where L::Target: Logger {
                                                .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 = candidate.htlc_minimum_msat();
                                        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);
@@ -1207,8 +1222,9 @@ where L::Target: Logger {
                                                // 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, aggregate_next_hops_cltv_delta);
+                                                       for details in first_channels {
+                                                               let candidate = CandidateRouteHop::FirstHop { details };
+                                                               add_entry!(candidate, our_node_id, NodeId::from_pubkey(&hop.src_node_id), aggregate_next_hops_fee_msat, path_value_msat, aggregate_next_hops_path_htlc_minimum_msat, aggregate_next_hops_path_penalty_msat, aggregate_next_hops_cltv_delta);
                                                        }
                                                }
                                        }
@@ -1242,9 +1258,9 @@ where L::Target: Logger {
                                'path_walk: loop {
                                        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();
+                                               for details in first_channels {
+                                                       if details.short_channel_id.unwrap() == ordered_hops.last().unwrap().0.candidate.short_channel_id() {
+                                                               ordered_hops.last_mut().unwrap().1 = details.counterparty.features.to_context();
                                                                features_set = true;
                                                                break;
                                                        }
@@ -1284,12 +1300,10 @@ where L::Target: Logger {
                                        // 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().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().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);
@@ -1314,7 +1328,7 @@ where L::Target: Logger {
                                // 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 = bookkept_channels_liquidity_available_msat.get_mut(&payment_hop.short_channel_id).unwrap();
+                                       let channel_liquidity_available_msat = bookkept_channels_liquidity_available_msat.get_mut(&payment_hop.candidate.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;
@@ -1329,7 +1343,7 @@ where L::Target: Logger {
                                        // 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_scid = payment_path.hops[(payment_path.hops.len() - 1) / 2].0.short_channel_id;
+                                       let victim_scid = payment_path.hops[(payment_path.hops.len() - 1) / 2].0.candidate.short_channel_id();
                                        log_trace!(logger, "Disabling channel {} for future path building iterations to avoid duplicates.", victim_scid);
                                        let victim_liquidity = bookkept_channels_liquidity_available_msat.get_mut(&victim_scid).unwrap();
                                        *victim_liquidity = 0;
@@ -1460,7 +1474,7 @@ where L::Target: Logger {
                                // 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.0.channel_fees.proportional_millionths as u64).sum::<u64>() });
+                               cur_route.sort_by_key(|path| { path.hops.iter().map(|hop| hop.0.candidate.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.
@@ -1478,16 +1492,22 @@ where L::Target: Logger {
        drawn_routes.sort_by_key(|paths| paths.iter().map(|path| path.get_total_fee_paid_msat()).sum::<u64>());
        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, node_features)| {
+               let mut path = 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(),
+                               short_channel_id: payment_hop.candidate.short_channel_id(),
+                               channel_features: payment_hop.candidate.features(),
                                fee_msat: payment_hop.fee_msat,
-                               cltv_expiry_delta: payment_hop.cltv_expiry_delta,
+                               cltv_expiry_delta: payment_hop.candidate.cltv_expiry_delta(),
                        })
-               }).collect());
+               }).collect::<Vec<_>>();
+               // Propagate the cltv_expiry_delta one hop backwards since the delta from the current hop is
+               // applicable for the previous hop.
+               path.iter_mut().rev().fold(final_cltv_expiry_delta, |prev_cltv_expiry_delta, hop| {
+                       core::mem::replace(&mut hop.as_mut().unwrap().cltv_expiry_delta, prev_cltv_expiry_delta)
+               });
+               selected_paths.push(path);
        }
 
        if let Some(features) = &payee.features {
@@ -2844,7 +2864,7 @@ mod tests {
                // 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][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);
@@ -4691,7 +4711,7 @@ mod tests {
                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 {
+               fn channel_penalty_msat(&self, short_channel_id: u64, _send_amt: u64, _capacity_msat: u64, _source: &NodeId, _target: &NodeId) -> u64 {
                        if short_channel_id == self.short_channel_id { u64::max_value() } else { 0 }
                }
 
@@ -4709,7 +4729,7 @@ mod tests {
        }
 
        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 {
+               fn channel_penalty_msat(&self, _short_channel_id: u64, _send_amt: u64, _capacity_msat: u64, _source: &NodeId, target: &NodeId) -> u64 {
                        if *target == self.node_id { u64::max_value() } else { 0 }
                }
 
@@ -4981,7 +5001,7 @@ mod benches {
        struct ZeroPenaltyScorer;
        impl Score for ZeroPenaltyScorer {
                fn channel_penalty_msat(
-                       &self, _short_channel_id: u64, _send_amt: u64, _capacity_msat: Option<u64>, _source: &NodeId, _target: &NodeId
+                       &self, _short_channel_id: u64, _send_amt: u64, _capacity_msat: u64, _source: &NodeId, _target: &NodeId
                ) -> u64 { 0 }
                fn payment_path_failed(&mut self, _path: &[&RouteHop], _short_channel_id: u64) {}
                fn payment_path_successful(&mut self, _path: &[&RouteHop]) {}
index 20a8afcabcf827298229cb44ff9903cbc000c9f6..810fd2020860a1e4af8894c88c7b34ab437e1703 100644 (file)
@@ -82,16 +82,11 @@ pub trait Score $(: $supertrait)* {
        /// Returns the fee in msats willing to be paid to avoid routing `send_amt_msat` through the
        /// given channel in the direction from `source` to `target`.
        ///
-       /// The channel's capacity (less any other MPP parts which are also being considered for use in
-       /// the same payment) is given by `channel_capacity_msat`. It may be guessed from various
-       /// sources or assumed from no data at all.
-       ///
-       /// For hints provided in the invoice, we assume the channel has sufficient capacity to accept
-       /// the invoice's full amount, and provide a `channel_capacity_msat` of `None`. In all other
-       /// cases it is set to `Some`, even if we're guessing at the channel value.
-       ///
-       /// Your code should be overflow-safe through a `channel_capacity_msat` of 21 million BTC.
-       fn channel_penalty_msat(&self, short_channel_id: u64, send_amt_msat: u64, channel_capacity_msat: Option<u64>, source: &NodeId, target: &NodeId) -> u64;
+       /// The channel's capacity (less any other MPP parts that are also being considered for use in
+       /// the same payment) is given by `capacity_msat`. It may be determined from various sources
+       /// such as a chain data, network gossip, or invoice hints, the latter indicating sufficient
+       /// capacity (i.e., near [`u64::max_value`]). Thus, implementations should be overflow-safe.
+       fn channel_penalty_msat(&self, short_channel_id: u64, send_amt_msat: u64, capacity_msat: u64, source: &NodeId, target: &NodeId) -> u64;
 
        /// Handles updating channel penalties after failing to route through a channel.
        fn payment_path_failed(&mut self, path: &[&RouteHop], short_channel_id: u64);
@@ -101,8 +96,8 @@ pub trait Score $(: $supertrait)* {
 }
 
 impl<S: Score, T: DerefMut<Target=S> $(+ $supertrait)*> Score for T {
-       fn channel_penalty_msat(&self, short_channel_id: u64, send_amt_msat: u64, channel_capacity_msat: Option<u64>, source: &NodeId, target: &NodeId) -> u64 {
-               self.deref().channel_penalty_msat(short_channel_id, send_amt_msat, channel_capacity_msat, source, target)
+       fn channel_penalty_msat(&self, short_channel_id: u64, send_amt_msat: u64, capacity_msat: u64, source: &NodeId, target: &NodeId) -> u64 {
+               self.deref().channel_penalty_msat(short_channel_id, send_amt_msat, capacity_msat, source, target)
        }
 
        fn payment_path_failed(&mut self, path: &[&RouteHop], short_channel_id: u64) {
@@ -369,23 +364,19 @@ impl Default for ScoringParameters {
 
 impl<T: Time> Score for ScorerUsingTime<T> {
        fn channel_penalty_msat(
-               &self, short_channel_id: u64, send_amt_msat: u64, chan_capacity_opt: Option<u64>, _source: &NodeId, _target: &NodeId
+               &self, short_channel_id: u64, send_amt_msat: u64, capacity_msat: u64, _source: &NodeId, _target: &NodeId
        ) -> u64 {
                let failure_penalty_msat = self.channel_failures
                        .get(&short_channel_id)
                        .map_or(0, |value| value.decayed_penalty_msat(self.params.failure_penalty_half_life));
 
                let mut penalty_msat = self.params.base_penalty_msat + failure_penalty_msat;
-
-               if let Some(chan_capacity_msat) = chan_capacity_opt {
-                       let send_1024ths = send_amt_msat.checked_mul(1024).unwrap_or(u64::max_value()) / chan_capacity_msat;
-
-                       if send_1024ths > self.params.overuse_penalty_start_1024th as u64 {
-                               penalty_msat = penalty_msat.checked_add(
-                                               (send_1024ths - self.params.overuse_penalty_start_1024th as u64)
-                                               .checked_mul(self.params.overuse_penalty_msat_per_1024th).unwrap_or(u64::max_value()))
-                                       .unwrap_or(u64::max_value());
-                       }
+               let send_1024ths = send_amt_msat.checked_mul(1024).unwrap_or(u64::max_value()) / capacity_msat;
+               if send_1024ths > self.params.overuse_penalty_start_1024th as u64 {
+                       penalty_msat = penalty_msat.checked_add(
+                                       (send_1024ths - self.params.overuse_penalty_start_1024th as u64)
+                                       .checked_mul(self.params.overuse_penalty_msat_per_1024th).unwrap_or(u64::max_value()))
+                               .unwrap_or(u64::max_value());
                }
 
                penalty_msat
@@ -622,10 +613,10 @@ mod tests {
                });
                let source = source_node_id();
                let target = target_node_id();
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_000);
 
                SinceEpoch::advance(Duration::from_secs(1));
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_000);
        }
 
        #[test]
@@ -639,16 +630,16 @@ mod tests {
                });
                let source = source_node_id();
                let target = target_node_id();
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_000);
 
                scorer.payment_path_failed(&[], 42);
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_064);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_064);
 
                scorer.payment_path_failed(&[], 42);
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_128);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_128);
 
                scorer.payment_path_failed(&[], 42);
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_192);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_192);
        }
 
        #[test]
@@ -662,25 +653,25 @@ mod tests {
                });
                let source = source_node_id();
                let target = target_node_id();
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_000);
 
                scorer.payment_path_failed(&[], 42);
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_512);
 
                SinceEpoch::advance(Duration::from_secs(9));
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_512);
 
                SinceEpoch::advance(Duration::from_secs(1));
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_256);
 
                SinceEpoch::advance(Duration::from_secs(10 * 8));
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_001);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_001);
 
                SinceEpoch::advance(Duration::from_secs(10));
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_000);
 
                SinceEpoch::advance(Duration::from_secs(10));
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_000);
        }
 
        #[test]
@@ -694,18 +685,18 @@ mod tests {
                });
                let source = source_node_id();
                let target = target_node_id();
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_000);
 
                scorer.payment_path_failed(&[], 42);
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_512);
 
                // An unchecked right shift 64 bits or more in ChannelFailure::decayed_penalty_msat would
                // cause an overflow.
                SinceEpoch::advance(Duration::from_secs(10 * 64));
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_000);
 
                SinceEpoch::advance(Duration::from_secs(10));
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_000);
        }
 
        #[test]
@@ -719,19 +710,19 @@ mod tests {
                });
                let source = source_node_id();
                let target = target_node_id();
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_000);
 
                scorer.payment_path_failed(&[], 42);
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_512);
 
                SinceEpoch::advance(Duration::from_secs(10));
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_256);
 
                scorer.payment_path_failed(&[], 42);
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_768);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_768);
 
                SinceEpoch::advance(Duration::from_secs(10));
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_384);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_384);
        }
 
        #[test]
@@ -745,13 +736,13 @@ mod tests {
                });
                let source = source_node_id();
                let target = target_node_id();
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_000);
 
                scorer.payment_path_failed(&[], 42);
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_512);
 
                SinceEpoch::advance(Duration::from_secs(10));
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_256);
 
                let hop = RouteHop {
                        pubkey: PublicKey::from_slice(target.as_slice()).unwrap(),
@@ -762,10 +753,10 @@ mod tests {
                        cltv_expiry_delta: 18,
                };
                scorer.payment_path_successful(&[&hop]);
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_128);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_128);
 
                SinceEpoch::advance(Duration::from_secs(10));
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_064);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_064);
        }
 
        #[test]
@@ -781,20 +772,20 @@ mod tests {
                let target = target_node_id();
 
                scorer.payment_path_failed(&[], 42);
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_512);
 
                SinceEpoch::advance(Duration::from_secs(10));
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_256);
 
                scorer.payment_path_failed(&[], 43);
-               assert_eq!(scorer.channel_penalty_msat(43, 1, Some(1), &source, &target), 1_512);
+               assert_eq!(scorer.channel_penalty_msat(43, 1, 1, &source, &target), 1_512);
 
                let mut serialized_scorer = Vec::new();
                scorer.write(&mut serialized_scorer).unwrap();
 
                let deserialized_scorer = <Scorer>::read(&mut io::Cursor::new(&serialized_scorer)).unwrap();
-               assert_eq!(deserialized_scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
-               assert_eq!(deserialized_scorer.channel_penalty_msat(43, 1, Some(1), &source, &target), 1_512);
+               assert_eq!(deserialized_scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_256);
+               assert_eq!(deserialized_scorer.channel_penalty_msat(43, 1, 1, &source, &target), 1_512);
        }
 
        #[test]
@@ -810,7 +801,7 @@ mod tests {
                let target = target_node_id();
 
                scorer.payment_path_failed(&[], 42);
-               assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
+               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_512);
 
                let mut serialized_scorer = Vec::new();
                scorer.write(&mut serialized_scorer).unwrap();
@@ -818,10 +809,10 @@ mod tests {
                SinceEpoch::advance(Duration::from_secs(10));
 
                let deserialized_scorer = <Scorer>::read(&mut io::Cursor::new(&serialized_scorer)).unwrap();
-               assert_eq!(deserialized_scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
+               assert_eq!(deserialized_scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_256);
 
                SinceEpoch::advance(Duration::from_secs(10));
-               assert_eq!(deserialized_scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_128);
+               assert_eq!(deserialized_scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_128);
        }
 
        #[test]
@@ -836,11 +827,10 @@ mod tests {
                let source = source_node_id();
                let target = target_node_id();
 
-               assert_eq!(scorer.channel_penalty_msat(42, 1_000, None, &source, &target), 0);
-               assert_eq!(scorer.channel_penalty_msat(42, 1_000, Some(1_024_000), &source, &target), 0);
-               assert_eq!(scorer.channel_penalty_msat(42, 256_999, Some(1_024_000), &source, &target), 0);
-               assert_eq!(scorer.channel_penalty_msat(42, 257_000, Some(1_024_000), &source, &target), 100);
-               assert_eq!(scorer.channel_penalty_msat(42, 258_000, Some(1_024_000), &source, &target), 200);
-               assert_eq!(scorer.channel_penalty_msat(42, 512_000, Some(1_024_000), &source, &target), 256 * 100);
+               assert_eq!(scorer.channel_penalty_msat(42, 1_000, 1_024_000, &source, &target), 0);
+               assert_eq!(scorer.channel_penalty_msat(42, 256_999, 1_024_000, &source, &target), 0);
+               assert_eq!(scorer.channel_penalty_msat(42, 257_000, 1_024_000, &source, &target), 100);
+               assert_eq!(scorer.channel_penalty_msat(42, 258_000, 1_024_000, &source, &target), 200);
+               assert_eq!(scorer.channel_penalty_msat(42, 512_000, 1_024_000, &source, &target), 256 * 100);
        }
 }