Make `htlc_maximum_msat` a required field.
[rust-lightning] / lightning / src / routing / scoring.rs
index bfcefc96f5b21b56a3d205d501948a7c9651a686..458a24d9f1bbd7ff83434837d6cd8c83d05a19af 100644 (file)
@@ -43,7 +43,7 @@
 //! let scorer = ProbabilisticScorer::new(params, &network_graph, &logger);
 //! # let random_seed_bytes = [42u8; 32];
 //!
-//! let route = find_route(&payer, &route_params, &network_graph.read_only(), None, &logger, &scorer, &random_seed_bytes);
+//! let route = find_route(&payer, &route_params, &network_graph, None, &logger, &scorer, &random_seed_bytes);
 //! # }
 //! ```
 //!
@@ -102,6 +102,12 @@ pub trait Score $(: $supertrait)* {
 
        /// Handles updating channel penalties after successfully routing along a path.
        fn payment_path_successful(&mut self, path: &[&RouteHop]);
+
+       /// Handles updating channel penalties after a probe over the given path failed.
+       fn probe_failed(&mut self, path: &[&RouteHop], short_channel_id: u64);
+
+       /// Handles updating channel penalties after a probe over the given path succeeded.
+       fn probe_successful(&mut self, path: &[&RouteHop]);
 }
 
 impl<S: Score, T: DerefMut<Target=S> $(+ $supertrait)*> Score for T {
@@ -118,6 +124,14 @@ impl<S: Score, T: DerefMut<Target=S> $(+ $supertrait)*> Score for T {
        fn payment_path_successful(&mut self, path: &[&RouteHop]) {
                self.deref_mut().payment_path_successful(path)
        }
+
+       fn probe_failed(&mut self, path: &[&RouteHop], short_channel_id: u64) {
+               self.deref_mut().probe_failed(path, short_channel_id)
+       }
+
+       fn probe_successful(&mut self, path: &[&RouteHop]) {
+               self.deref_mut().probe_successful(path)
+       }
 }
 } }
 
@@ -241,6 +255,10 @@ impl Score for FixedPenaltyScorer {
        fn payment_path_failed(&mut self, _path: &[&RouteHop], _short_channel_id: u64) {}
 
        fn payment_path_successful(&mut self, _path: &[&RouteHop]) {}
+
+       fn probe_failed(&mut self, _path: &[&RouteHop], _short_channel_id: u64) {}
+
+       fn probe_successful(&mut self, _path: &[&RouteHop]) {}
 }
 
 impl Writeable for FixedPenaltyScorer {
@@ -306,7 +324,7 @@ where L::Target: Logger {
 ///
 /// Used to configure base, liquidity, and amount penalties, the sum of which comprises the channel
 /// penalty (i.e., the amount in msats willing to be paid to avoid routing through the channel).
-#[derive(Clone, Copy)]
+#[derive(Clone)]
 pub struct ProbabilisticScoringParameters {
        /// A fixed penalty in msats to apply to each channel.
        ///
@@ -361,6 +379,40 @@ pub struct ProbabilisticScoringParameters {
        ///
        /// Default value: 256 msat
        pub amount_penalty_multiplier_msat: u64,
+
+       /// Manual penalties used for the given nodes. Allows to set a particular penalty for a given
+       /// node. Note that a manual penalty of `u64::max_value()` means the node would not ever be
+       /// considered during path finding.
+       ///
+       /// (C-not exported)
+       pub manual_node_penalties: HashMap<NodeId, u64>,
+
+       /// This penalty is applied when `htlc_maximum_msat` is equal to or larger than half of the
+       /// channel's capacity, which makes us prefer nodes with a smaller `htlc_maximum_msat`. We
+       /// treat such nodes preferentially as this makes balance discovery attacks harder to execute,
+       /// thereby creating an incentive to restrict `htlc_maximum_msat` and improve privacy.
+       ///
+       /// Default value: 250 msat
+       pub anti_probing_penalty_msat: u64,
+
+       /// This penalty is applied when the amount we're attempting to send over a channel exceeds our
+       /// current estimate of the channel's available liquidity.
+       ///
+       /// Note that in this case all other penalties, including the
+       /// [`liquidity_penalty_multiplier_msat`] and [`amount_penalty_multiplier_msat`]-based
+       /// penalties, as well as the [`base_penalty_msat`] and the [`anti_probing_penalty_msat`], if
+       /// applicable, are still included in the overall penalty.
+       ///
+       /// If you wish to avoid creating paths with such channels entirely, setting this to a value of
+       /// `u64::max_value()` will guarantee that.
+       ///
+       /// Default value: 1_0000_0000_000 msat (1 Bitcoin)
+       ///
+       /// [`liquidity_penalty_multiplier_msat`]: Self::liquidity_penalty_multiplier_msat
+       /// [`amount_penalty_multiplier_msat`]: Self::amount_penalty_multiplier_msat
+       /// [`base_penalty_msat`]: Self::base_penalty_msat
+       /// [`anti_probing_penalty_msat`]: Self::anti_probing_penalty_msat
+       pub considered_impossible_penalty_msat: u64,
 }
 
 /// Accounting for channel liquidity balance uncertainty.
@@ -434,6 +486,49 @@ impl<G: Deref<Target = NetworkGraph<L>>, L: Deref, T: Time> ProbabilisticScorerU
                        }
                }
        }
+
+       /// Query the estimated minimum and maximum liquidity available for sending a payment over the
+       /// channel with `scid` towards the given `target` node.
+       pub fn estimated_channel_liquidity_range(&self, scid: u64, target: &NodeId) -> Option<(u64, u64)> {
+               let graph = self.network_graph.read_only();
+
+               if let Some(chan) = graph.channels().get(&scid) {
+                       if let Some(liq) = self.channel_liquidities.get(&scid) {
+                               if let Some((directed_info, source)) = chan.as_directed_to(target) {
+                                       let amt = directed_info.effective_capacity().as_msat();
+                                       let dir_liq = liq.as_directed(source, target, amt, self.params.liquidity_offset_half_life);
+                                       return Some((dir_liq.min_liquidity_msat(), dir_liq.max_liquidity_msat()));
+                               }
+                       }
+               }
+               None
+       }
+
+       /// Marks the node with the given `node_id` as banned, i.e.,
+       /// it will be avoided during path finding.
+       pub fn add_banned(&mut self, node_id: &NodeId) {
+               self.params.manual_node_penalties.insert(*node_id, u64::max_value());
+       }
+
+       /// Removes the node with the given `node_id` from the list of nodes to avoid.
+       pub fn remove_banned(&mut self, node_id: &NodeId) {
+               self.params.manual_node_penalties.remove(node_id);
+       }
+
+       /// Sets a manual penalty for the given node.
+       pub fn set_manual_penalty(&mut self, node_id: &NodeId, penalty: u64) {
+               self.params.manual_node_penalties.insert(*node_id, penalty);
+       }
+
+       /// Removes the node with the given `node_id` from the list of manual penalties.
+       pub fn remove_manual_penalty(&mut self, node_id: &NodeId) {
+               self.params.manual_node_penalties.remove(node_id);
+       }
+
+       /// Clears the list of manual penalties that are applied during path finding.
+       pub fn clear_manual_penalties(&mut self) {
+               self.params.manual_node_penalties = HashMap::new();
+       }
 }
 
 impl ProbabilisticScoringParameters {
@@ -444,6 +539,17 @@ impl ProbabilisticScoringParameters {
                        liquidity_penalty_multiplier_msat: 0,
                        liquidity_offset_half_life: Duration::from_secs(3600),
                        amount_penalty_multiplier_msat: 0,
+                       manual_node_penalties: HashMap::new(),
+                       anti_probing_penalty_msat: 0,
+                       considered_impossible_penalty_msat: 0,
+               }
+       }
+
+       /// Marks all nodes in the given list as banned, i.e.,
+       /// they will be avoided during path finding.
+       pub fn add_banned_from_list(&mut self, node_ids: Vec<NodeId>) {
+               for id in node_ids {
+                       self.manual_node_penalties.insert(id, u64::max_value());
                }
        }
 }
@@ -455,6 +561,9 @@ impl Default for ProbabilisticScoringParameters {
                        liquidity_penalty_multiplier_msat: 40_000,
                        liquidity_offset_half_life: Duration::from_secs(3600),
                        amount_penalty_multiplier_msat: 256,
+                       manual_node_penalties: HashMap::new(),
+                       anti_probing_penalty_msat: 250,
+                       considered_impossible_penalty_msat: 1_0000_0000_000,
                }
        }
 }
@@ -526,23 +635,18 @@ const AMOUNT_PENALTY_DIVISOR: u64 = 1 << 20;
 impl<L: Deref<Target = u64>, T: Time, U: Deref<Target = T>> DirectedChannelLiquidity<L, T, U> {
        /// Returns a penalty for routing the given HTLC `amount_msat` through the channel in this
        /// direction.
-       fn penalty_msat(&self, amount_msat: u64, params: ProbabilisticScoringParameters) -> u64 {
+       fn penalty_msat(&self, amount_msat: u64, params: &ProbabilisticScoringParameters) -> u64 {
                let max_liquidity_msat = self.max_liquidity_msat();
                let min_liquidity_msat = core::cmp::min(self.min_liquidity_msat(), max_liquidity_msat);
                if amount_msat <= min_liquidity_msat {
                        0
                } else if amount_msat >= max_liquidity_msat {
-                       if amount_msat > max_liquidity_msat {
-                               u64::max_value()
-                       } else if max_liquidity_msat != self.capacity_msat {
-                               // Avoid using the failed channel on retry.
-                               u64::max_value()
-                       } else {
-                               // Equivalent to hitting the else clause below with the amount equal to the
-                               // effective capacity and without any certainty on the liquidity upper bound.
-                               let negative_log10_times_2048 = NEGATIVE_LOG10_UPPER_BOUND * 2048;
-                               self.combined_penalty_msat(amount_msat, negative_log10_times_2048, params)
-                       }
+                       // Equivalent to hitting the else clause below with the amount equal to the effective
+                       // capacity and without any certainty on the liquidity upper bound, plus the
+                       // impossibility penalty.
+                       let negative_log10_times_2048 = NEGATIVE_LOG10_UPPER_BOUND * 2048;
+                       self.combined_penalty_msat(amount_msat, negative_log10_times_2048, params)
+                               .saturating_add(params.considered_impossible_penalty_msat)
                } else {
                        let numerator = (max_liquidity_msat - amount_msat).saturating_add(1);
                        let denominator = (max_liquidity_msat - min_liquidity_msat).saturating_add(1);
@@ -563,7 +667,7 @@ impl<L: Deref<Target = u64>, T: Time, U: Deref<Target = T>> DirectedChannelLiqui
        #[inline(always)]
        fn combined_penalty_msat(
                &self, amount_msat: u64, negative_log10_times_2048: u64,
-               params: ProbabilisticScoringParameters
+               params: &ProbabilisticScoringParameters
        ) -> u64 {
                let liquidity_penalty_msat = {
                        // Upper bound the liquidity penalty to ensure some channel is selected.
@@ -655,12 +759,25 @@ impl<G: Deref<Target = NetworkGraph<L>>, L: Deref, T: Time> Score for Probabilis
        fn channel_penalty_msat(
                &self, short_channel_id: u64, source: &NodeId, target: &NodeId, usage: ChannelUsage
        ) -> u64 {
-               if let EffectiveCapacity::ExactLiquidity { liquidity_msat } = usage.effective_capacity {
-                       if usage.amount_msat > liquidity_msat {
-                               return u64::max_value();
-                       } else {
-                               return self.params.base_penalty_msat;
-                       };
+               if let Some(penalty) = self.params.manual_node_penalties.get(target) {
+                       return *penalty;
+               }
+
+               let mut anti_probing_penalty_msat = 0;
+               match usage.effective_capacity {
+                       EffectiveCapacity::ExactLiquidity { liquidity_msat } => {
+                               if usage.amount_msat > liquidity_msat {
+                                       return u64::max_value();
+                               } else {
+                                       return self.params.base_penalty_msat;
+                               }
+                       },
+                       EffectiveCapacity::Total { capacity_msat, htlc_maximum_msat: Some(htlc_maximum_msat) } => {
+                               if htlc_maximum_msat >= capacity_msat/2 {
+                                       anti_probing_penalty_msat = self.params.anti_probing_penalty_msat;
+                               }
+                       },
+                       _ => {},
                }
 
                let liquidity_offset_half_life = self.params.liquidity_offset_half_life;
@@ -671,7 +788,8 @@ impl<G: Deref<Target = NetworkGraph<L>>, L: Deref, T: Time> Score for Probabilis
                        .get(&short_channel_id)
                        .unwrap_or(&ChannelLiquidity::new())
                        .as_directed(source, target, capacity_msat, liquidity_offset_half_life)
-                       .penalty_msat(amount_msat, self.params)
+                       .penalty_msat(amount_msat, &self.params)
+                       .saturating_add(anti_probing_penalty_msat)
        }
 
        fn payment_path_failed(&mut self, path: &[&RouteHop], short_channel_id: u64) {
@@ -739,6 +857,14 @@ impl<G: Deref<Target = NetworkGraph<L>>, L: Deref, T: Time> Score for Probabilis
                        }
                }
        }
+
+       fn probe_failed(&mut self, path: &[&RouteHop], short_channel_id: u64) {
+               self.payment_path_failed(path, short_channel_id)
+       }
+
+       fn probe_successful(&mut self, path: &[&RouteHop]) {
+               self.payment_path_failed(path, u64::max_value())
+       }
 }
 
 mod approx {
@@ -1055,7 +1181,7 @@ impl<G: Deref<Target = NetworkGraph<L>>, L: Deref, T: Time> Writeable for Probab
        #[inline]
        fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
                write_tlv_fields!(w, {
-                       (0, self.channel_liquidities, required)
+                       (0, self.channel_liquidities, required),
                });
                Ok(())
        }
@@ -1070,7 +1196,7 @@ ReadableArgs<(ProbabilisticScoringParameters, G, L)> for ProbabilisticScorerUsin
                let (params, network_graph, logger) = args;
                let mut channel_liquidities = HashMap::new();
                read_tlv_fields!(r, {
-                       (0, channel_liquidities, required)
+                       (0, channel_liquidities, required),
                });
                Ok(Self {
                        params,
@@ -1105,10 +1231,22 @@ impl<T: Time> Readable for ChannelLiquidity<T> {
                        (2, max_liquidity_offset_msat, required),
                        (4, duration_since_epoch, required),
                });
+               // On rust prior to 1.60 `Instant::duration_since` will panic if time goes backwards.
+               // We write `last_updated` as wallclock time even though its ultimately an `Instant` (which
+               // is a time from a monotonic clock usually represented as an offset against boot time).
+               // Thus, we have to construct an `Instant` by subtracting the difference in wallclock time
+               // from the one that was written. However, because `Instant` can panic if we construct one
+               // in the future, we must handle wallclock time jumping backwards, which we do by simply
+               // using `Instant::now()` in that case.
+               let wall_clock_now = T::duration_since_epoch();
+               let now = T::now();
+               let last_updated = if wall_clock_now > duration_since_epoch {
+                       now - (wall_clock_now - duration_since_epoch)
+               } else { now };
                Ok(Self {
                        min_liquidity_offset_msat,
                        max_liquidity_offset_msat,
-                       last_updated: T::now() - (T::duration_since_epoch() - duration_since_epoch),
+                       last_updated,
                })
        }
 }
@@ -1120,7 +1258,7 @@ mod tests {
        use util::time::tests::SinceEpoch;
 
        use ln::features::{ChannelFeatures, NodeFeatures};
-       use ln::msgs::{ChannelAnnouncement, ChannelUpdate, OptionalField, UnsignedChannelAnnouncement, UnsignedChannelUpdate};
+       use ln::msgs::{ChannelAnnouncement, ChannelUpdate, UnsignedChannelAnnouncement, UnsignedChannelUpdate};
        use routing::gossip::{EffectiveCapacity, NetworkGraph, NodeId};
        use routing::router::RouteHop;
        use routing::scoring::{ChannelUsage, Score};
@@ -1247,7 +1385,7 @@ mod tests {
                        flags,
                        cltv_expiry_delta: 18,
                        htlc_minimum_msat: 0,
-                       htlc_maximum_msat: OptionalField::Present(1_000),
+                       htlc_maximum_msat: 1_000,
                        fee_base_msat: 1,
                        fee_proportional_millionths: 0,
                        excess_data: Vec::new(),
@@ -1495,20 +1633,20 @@ mod tests {
                let usage = ChannelUsage {
                        amount_msat: 1_024,
                        inflight_htlc_msat: 0,
-                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_024_000 },
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_024_000, htlc_maximum_msat: Some(1_000) },
                };
                assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 0);
                let usage = ChannelUsage { amount_msat: 10_240, ..usage };
                assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 0);
                let usage = ChannelUsage { amount_msat: 102_400, ..usage };
                assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 47);
-               let usage = ChannelUsage { amount_msat: 1_024_000, ..usage };
+               let usage = ChannelUsage { amount_msat: 1_023_999, ..usage };
                assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 2_000);
 
                let usage = ChannelUsage {
                        amount_msat: 128,
                        inflight_htlc_msat: 0,
-                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_024 },
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_024, htlc_maximum_msat: Some(1_000) },
                };
                assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 58);
                let usage = ChannelUsage { amount_msat: 256, ..usage };
@@ -1532,6 +1670,7 @@ mod tests {
                let network_graph = network_graph(&logger);
                let params = ProbabilisticScoringParameters {
                        liquidity_penalty_multiplier_msat: 1_000,
+                       considered_impossible_penalty_msat: u64::max_value(),
                        ..ProbabilisticScoringParameters::zero_penalty()
                };
                let scorer = ProbabilisticScorer::new(params, &network_graph, &logger)
@@ -1545,7 +1684,7 @@ mod tests {
                let usage = ChannelUsage {
                        amount_msat: 39,
                        inflight_htlc_msat: 0,
-                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 100 },
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 100, htlc_maximum_msat: Some(1_000) },
                };
                assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 0);
                let usage = ChannelUsage { amount_msat: 50, ..usage };
@@ -1569,7 +1708,7 @@ mod tests {
                let usage = ChannelUsage {
                        amount_msat: 500,
                        inflight_htlc_msat: 0,
-                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_000 },
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_000, htlc_maximum_msat: Some(1_000) },
                };
                let failed_path = payment_path_for_amount(500);
                let successful_path = payment_path_for_amount(200);
@@ -1599,7 +1738,7 @@ mod tests {
                let usage = ChannelUsage {
                        amount_msat: 250,
                        inflight_htlc_msat: 0,
-                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_000 },
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_000, htlc_maximum_msat: Some(1_000) },
                };
                assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 128);
                let usage = ChannelUsage { amount_msat: 500, ..usage };
@@ -1623,6 +1762,7 @@ mod tests {
                let network_graph = network_graph(&logger);
                let params = ProbabilisticScoringParameters {
                        liquidity_penalty_multiplier_msat: 1_000,
+                       considered_impossible_penalty_msat: u64::max_value(),
                        ..ProbabilisticScoringParameters::zero_penalty()
                };
                let mut scorer = ProbabilisticScorer::new(params, &network_graph, &logger);
@@ -1633,7 +1773,7 @@ mod tests {
                let usage = ChannelUsage {
                        amount_msat: 250,
                        inflight_htlc_msat: 0,
-                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_000 },
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_000, htlc_maximum_msat: Some(1_000) },
                };
                assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 128);
                let usage = ChannelUsage { amount_msat: 500, ..usage };
@@ -1667,7 +1807,7 @@ mod tests {
                let usage = ChannelUsage {
                        amount_msat: 250,
                        inflight_htlc_msat: 0,
-                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_000 },
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_000, htlc_maximum_msat: Some(1_000) },
                };
                let path = payment_path_for_amount(500);
 
@@ -1689,6 +1829,7 @@ mod tests {
                let params = ProbabilisticScoringParameters {
                        liquidity_penalty_multiplier_msat: 1_000,
                        liquidity_offset_half_life: Duration::from_secs(10),
+                       considered_impossible_penalty_msat: u64::max_value(),
                        ..ProbabilisticScoringParameters::zero_penalty()
                };
                let mut scorer = ProbabilisticScorer::new(params, &network_graph, &logger);
@@ -1698,10 +1839,10 @@ mod tests {
                let usage = ChannelUsage {
                        amount_msat: 0,
                        inflight_htlc_msat: 0,
-                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_024 },
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_024, htlc_maximum_msat: Some(1_024) },
                };
                assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 0);
-               let usage = ChannelUsage { amount_msat: 1_024, ..usage };
+               let usage = ChannelUsage { amount_msat: 1_023, ..usage };
                assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 2_000);
 
                scorer.payment_path_failed(&payment_path_for_amount(768).iter().collect::<Vec<_>>(), 42);
@@ -1745,20 +1886,20 @@ mod tests {
                let usage = ChannelUsage { amount_msat: 1_023, ..usage };
                assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 2_000);
                let usage = ChannelUsage { amount_msat: 1_024, ..usage };
-               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 2_000);
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), u64::max_value());
 
                // Fully decay liquidity upper bound.
                SinceEpoch::advance(Duration::from_secs(10));
                let usage = ChannelUsage { amount_msat: 0, ..usage };
                assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 0);
                let usage = ChannelUsage { amount_msat: 1_024, ..usage };
-               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 2_000);
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), u64::max_value());
 
                SinceEpoch::advance(Duration::from_secs(10));
                let usage = ChannelUsage { amount_msat: 0, ..usage };
                assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 0);
                let usage = ChannelUsage { amount_msat: 1_024, ..usage };
-               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 2_000);
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), u64::max_value());
        }
 
        #[test]
@@ -1776,7 +1917,7 @@ mod tests {
                let usage = ChannelUsage {
                        amount_msat: 256,
                        inflight_htlc_msat: 0,
-                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_024 },
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_024, htlc_maximum_msat: Some(1_000) },
                };
                assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 125);
 
@@ -1807,7 +1948,7 @@ mod tests {
                let usage = ChannelUsage {
                        amount_msat: 512,
                        inflight_htlc_msat: 0,
-                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_024 },
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_024, htlc_maximum_msat: Some(1_000) },
                };
 
                assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 300);
@@ -1843,15 +1984,16 @@ mod tests {
                let params = ProbabilisticScoringParameters {
                        liquidity_penalty_multiplier_msat: 1_000,
                        liquidity_offset_half_life: Duration::from_secs(10),
+                       considered_impossible_penalty_msat: u64::max_value(),
                        ..ProbabilisticScoringParameters::zero_penalty()
                };
-               let mut scorer = ProbabilisticScorer::new(params, &network_graph, &logger);
+               let mut scorer = ProbabilisticScorer::new(params.clone(), &network_graph, &logger);
                let source = source_node_id();
                let target = target_node_id();
                let usage = ChannelUsage {
                        amount_msat: 500,
                        inflight_htlc_msat: 0,
-                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_000 },
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_000, htlc_maximum_msat: Some(1_000) },
                };
 
                scorer.payment_path_failed(&payment_path_for_amount(500).iter().collect::<Vec<_>>(), 42);
@@ -1879,15 +2021,16 @@ mod tests {
                let params = ProbabilisticScoringParameters {
                        liquidity_penalty_multiplier_msat: 1_000,
                        liquidity_offset_half_life: Duration::from_secs(10),
+                       considered_impossible_penalty_msat: u64::max_value(),
                        ..ProbabilisticScoringParameters::zero_penalty()
                };
-               let mut scorer = ProbabilisticScorer::new(params, &network_graph, &logger);
+               let mut scorer = ProbabilisticScorer::new(params.clone(), &network_graph, &logger);
                let source = source_node_id();
                let target = target_node_id();
                let usage = ChannelUsage {
                        amount_msat: 500,
                        inflight_htlc_msat: 0,
-                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_000 },
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_000, htlc_maximum_msat: Some(1_000) },
                };
 
                scorer.payment_path_failed(&payment_path_for_amount(500).iter().collect::<Vec<_>>(), 42);
@@ -1924,47 +2067,47 @@ mod tests {
                let usage = ChannelUsage {
                        amount_msat: 100_000_000,
                        inflight_htlc_msat: 0,
-                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 950_000_000 },
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 950_000_000, htlc_maximum_msat: Some(1_000) },
                };
                assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 3613);
                let usage = ChannelUsage {
-                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_950_000_000 }, ..usage
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_950_000_000, htlc_maximum_msat: Some(1_000) }, ..usage
                };
                assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 1977);
                let usage = ChannelUsage {
-                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 2_950_000_000 }, ..usage
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 2_950_000_000, htlc_maximum_msat: Some(1_000) }, ..usage
                };
                assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 1474);
                let usage = ChannelUsage {
-                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 3_950_000_000 }, ..usage
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 3_950_000_000, htlc_maximum_msat: Some(1_000) }, ..usage
                };
                assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 1223);
                let usage = ChannelUsage {
-                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 4_950_000_000 }, ..usage
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 4_950_000_000, htlc_maximum_msat: Some(1_000) }, ..usage
                };
                assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 877);
                let usage = ChannelUsage {
-                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 5_950_000_000 }, ..usage
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 5_950_000_000, htlc_maximum_msat: Some(1_000) }, ..usage
                };
                assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 845);
                let usage = ChannelUsage {
-                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 6_950_000_000 }, ..usage
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 6_950_000_000, htlc_maximum_msat: Some(1_000) }, ..usage
                };
                assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 500);
                let usage = ChannelUsage {
-                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 7_450_000_000 }, ..usage
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 7_450_000_000, htlc_maximum_msat: Some(1_000) }, ..usage
                };
                assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 500);
                let usage = ChannelUsage {
-                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 7_950_000_000 }, ..usage
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 7_950_000_000, htlc_maximum_msat: Some(1_000) }, ..usage
                };
                assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 500);
                let usage = ChannelUsage {
-                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 8_950_000_000 }, ..usage
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 8_950_000_000, htlc_maximum_msat: Some(1_000) }, ..usage
                };
                assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 500);
                let usage = ChannelUsage {
-                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 9_950_000_000 }, ..usage
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 9_950_000_000, htlc_maximum_msat: Some(1_000) }, ..usage
                };
                assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 500);
        }
@@ -1978,7 +2121,7 @@ mod tests {
                let usage = ChannelUsage {
                        amount_msat: 128,
                        inflight_htlc_msat: 0,
-                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_024 },
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_024, htlc_maximum_msat: Some(1_000) },
                };
 
                let params = ProbabilisticScoringParameters {
@@ -1989,7 +2132,8 @@ mod tests {
                assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 58);
 
                let params = ProbabilisticScoringParameters {
-                       base_penalty_msat: 500, liquidity_penalty_multiplier_msat: 1_000, ..Default::default()
+                       base_penalty_msat: 500, liquidity_penalty_multiplier_msat: 1_000,
+                       anti_probing_penalty_msat: 0, ..Default::default()
                };
                let scorer = ProbabilisticScorer::new(params, &network_graph, &logger);
                assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 558);
@@ -2004,7 +2148,7 @@ mod tests {
                let usage = ChannelUsage {
                        amount_msat: 512_000,
                        inflight_htlc_msat: 0,
-                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_024_000 },
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_024_000, htlc_maximum_msat: Some(1_000) },
                };
 
                let params = ProbabilisticScoringParameters {
@@ -2048,7 +2192,10 @@ mod tests {
        fn accounts_for_inflight_htlc_usage() {
                let logger = TestLogger::new();
                let network_graph = network_graph(&logger);
-               let params = ProbabilisticScoringParameters::default();
+               let params = ProbabilisticScoringParameters {
+                       considered_impossible_penalty_msat: u64::max_value(),
+                       ..ProbabilisticScoringParameters::zero_penalty()
+               };
                let scorer = ProbabilisticScorer::new(params, &network_graph, &logger);
                let source = source_node_id();
                let target = target_node_id();
@@ -2056,7 +2203,7 @@ mod tests {
                let usage = ChannelUsage {
                        amount_msat: 750,
                        inflight_htlc_msat: 0,
-                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_000 },
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_000, htlc_maximum_msat: Some(1_000) },
                };
                assert_ne!(scorer.channel_penalty_msat(42, &source, &target, usage), u64::max_value());
 
@@ -2069,7 +2216,7 @@ mod tests {
                let logger = TestLogger::new();
                let network_graph = network_graph(&logger);
                let params = ProbabilisticScoringParameters::default();
-               let scorer = ProbabilisticScorer::new(params, &network_graph, &logger);
+               let scorer = ProbabilisticScorer::new(params.clone(), &network_graph, &logger);
                let source = source_node_id();
                let target = target_node_id();
 
@@ -2087,4 +2234,49 @@ mod tests {
                let usage = ChannelUsage { amount_msat: 1_001, ..usage };
                assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), u64::max_value());
        }
+
+       #[test]
+       fn adds_anti_probing_penalty() {
+               let logger = TestLogger::new();
+               let network_graph = network_graph(&logger);
+               let source = source_node_id();
+               let target = target_node_id();
+               let params = ProbabilisticScoringParameters {
+                       anti_probing_penalty_msat: 500,
+                       ..ProbabilisticScoringParameters::zero_penalty()
+               };
+               let scorer = ProbabilisticScorer::new(params, &network_graph, &logger);
+
+               // Check we receive no penalty for a low htlc_maximum_msat.
+               let usage = ChannelUsage {
+                       amount_msat: 512_000,
+                       inflight_htlc_msat: 0,
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_024_000, htlc_maximum_msat: Some(1_000) },
+               };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 0);
+
+               // Check we receive anti-probing penalty for htlc_maximum_msat == channel_capacity.
+               let usage = ChannelUsage {
+                       amount_msat: 512_000,
+                       inflight_htlc_msat: 0,
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_024_000, htlc_maximum_msat: Some(1_024_000) },
+               };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 500);
+
+               // Check we receive anti-probing penalty for htlc_maximum_msat == channel_capacity/2.
+               let usage = ChannelUsage {
+                       amount_msat: 512_000,
+                       inflight_htlc_msat: 0,
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_024_000, htlc_maximum_msat: Some(512_000) },
+               };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 500);
+
+               // Check we receive no anti-probing penalty for htlc_maximum_msat == channel_capacity/2 - 1.
+               let usage = ChannelUsage {
+                       amount_msat: 512_000,
+                       inflight_htlc_msat: 0,
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_024_000, htlc_maximum_msat: Some(511_999) },
+               };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 0);
+       }
 }