Make the `P2PGossipSync` `UtxoLookup` exchangable without &mut self
[rust-lightning] / lightning / src / routing / router.rs
index ef6fef0a7eb42ea87b8d0876f0b11f99112d83cb..7abca061f3b480cfd9d011b9bd70cdbc53778b76 100644 (file)
@@ -16,9 +16,9 @@ use bitcoin::hashes::sha256::Hash as Sha256;
 use crate::blinded_path::{BlindedHop, BlindedPath};
 use crate::ln::PaymentHash;
 use crate::ln::channelmanager::{ChannelDetails, PaymentId};
-use crate::ln::features::{Bolt12InvoiceFeatures, ChannelFeatures, InvoiceFeatures, NodeFeatures};
+use crate::ln::features::{Bolt11InvoiceFeatures, Bolt12InvoiceFeatures, ChannelFeatures, NodeFeatures};
 use crate::ln::msgs::{DecodeError, ErrorAction, LightningError, MAX_VALUE_MSAT};
-use crate::offers::invoice::BlindedPayInfo;
+use crate::offers::invoice::{BlindedPayInfo, Bolt12Invoice};
 use crate::routing::gossip::{DirectedChannelInfo, EffectiveCapacity, ReadOnlyNetworkGraph, NetworkGraph, NodeId, RoutingFees};
 use crate::routing::scoring::{ChannelUsage, LockableScore, Score};
 use crate::util::ser::{Writeable, Readable, ReadableArgs, Writer};
@@ -27,15 +27,15 @@ use crate::util::chacha20::ChaCha20;
 
 use crate::io;
 use crate::prelude::*;
-use crate::sync::{Mutex, MutexGuard};
+use crate::sync::{Mutex};
 use alloc::collections::BinaryHeap;
 use core::{cmp, fmt};
-use core::ops::Deref;
+use core::ops::{Deref, DerefMut};
 
 /// A [`Router`] implemented using [`find_route`].
 pub struct DefaultRouter<G: Deref<Target = NetworkGraph<L>>, L: Deref, S: Deref, SP: Sized, Sc: Score<ScoreParams = SP>> where
        L::Target: Logger,
-       S::Target: for <'a> LockableScore<'a, Locked = MutexGuard<'a, Sc>>,
+       S::Target: for <'a> LockableScore<'a, Score = Sc>,
 {
        network_graph: G,
        logger: L,
@@ -46,7 +46,7 @@ pub struct DefaultRouter<G: Deref<Target = NetworkGraph<L>>, L: Deref, S: Deref,
 
 impl<G: Deref<Target = NetworkGraph<L>>, L: Deref, S: Deref, SP: Sized, Sc: Score<ScoreParams = SP>> DefaultRouter<G, L, S, SP, Sc> where
        L::Target: Logger,
-       S::Target: for <'a> LockableScore<'a, Locked = MutexGuard<'a, Sc>>,
+       S::Target: for <'a> LockableScore<'a, Score = Sc>,
 {
        /// Creates a new router.
        pub fn new(network_graph: G, logger: L, random_seed_bytes: [u8; 32], scorer: S, score_params: SP) -> Self {
@@ -55,16 +55,16 @@ impl<G: Deref<Target = NetworkGraph<L>>, L: Deref, S: Deref, SP: Sized, Sc: Scor
        }
 }
 
-impl< G: Deref<Target = NetworkGraph<L>>, L: Deref, S: Deref,  SP: Sized, Sc: Score<ScoreParams = SP>> Router for DefaultRouter<G, L, S, SP, Sc> where
+impl< G: Deref<Target = NetworkGraph<L>>, L: Deref, S: Deref, SP: Sized, Sc: Score<ScoreParams = SP>> Router for DefaultRouter<G, L, S, SP, Sc> where
        L::Target: Logger,
-       S::Target: for <'a> LockableScore<'a, Locked = MutexGuard<'a, Sc>>,
+       S::Target: for <'a> LockableScore<'a, Score = Sc>,
 {
        fn find_route(
                &self,
                payer: &PublicKey,
                params: &RouteParameters,
                first_hops: Option<&[&ChannelDetails]>,
-               inflight_htlcs: &InFlightHtlcs
+               inflight_htlcs: InFlightHtlcs
        ) -> Result<Route, LightningError> {
                let random_seed_bytes = {
                        let mut locked_random_seed_bytes = self.random_seed_bytes.lock().unwrap();
@@ -73,7 +73,7 @@ impl< G: Deref<Target = NetworkGraph<L>>, L: Deref, S: Deref,  SP: Sized, Sc: Sc
                };
                find_route(
                        payer, params, &self.network_graph, first_hops, &*self.logger,
-                       &ScorerAccountingForInFlightHtlcs::new(self.scorer.lock()inflight_htlcs),
+                       &ScorerAccountingForInFlightHtlcs::new(self.scorer.lock().deref_mut(), &inflight_htlcs),
                        &self.score_params,
                        &random_seed_bytes
                )
@@ -82,16 +82,24 @@ impl< G: Deref<Target = NetworkGraph<L>>, L: Deref, S: Deref,  SP: Sized, Sc: Sc
 
 /// A trait defining behavior for routing a payment.
 pub trait Router {
-       /// Finds a [`Route`] between `payer` and `payee` for a payment with the given values.
+       /// Finds a [`Route`] for a payment between the given `payer` and a payee.
+       ///
+       /// The `payee` and the payment's value are given in [`RouteParameters::payment_params`]
+       /// and [`RouteParameters::final_value_msat`], respectively.
        fn find_route(
                &self, payer: &PublicKey, route_params: &RouteParameters,
-               first_hops: Option<&[&ChannelDetails]>, inflight_htlcs: &InFlightHtlcs
+               first_hops: Option<&[&ChannelDetails]>, inflight_htlcs: InFlightHtlcs
        ) -> Result<Route, LightningError>;
-       /// Finds a [`Route`] between `payer` and `payee` for a payment with the given values. Includes
-       /// `PaymentHash` and `PaymentId` to be able to correlate the request with a specific payment.
+       /// Finds a [`Route`] for a payment between the given `payer` and a payee.
+       ///
+       /// The `payee` and the payment's value are given in [`RouteParameters::payment_params`]
+       /// and [`RouteParameters::final_value_msat`], respectively.
+       ///
+       /// Includes a [`PaymentHash`] and a [`PaymentId`] to be able to correlate the request with a specific
+       /// payment.
        fn find_route_with_id(
                &self, payer: &PublicKey, route_params: &RouteParameters,
-               first_hops: Option<&[&ChannelDetails]>, inflight_htlcs: &InFlightHtlcs,
+               first_hops: Option<&[&ChannelDetails]>, inflight_htlcs: InFlightHtlcs,
                _payment_hash: PaymentHash, _payment_id: PaymentId
        ) -> Result<Route, LightningError> {
                self.find_route(payer, route_params, first_hops, inflight_htlcs)
@@ -104,15 +112,15 @@ pub trait Router {
 /// [`find_route`].
 ///
 /// [`Score`]: crate::routing::scoring::Score
-pub struct ScorerAccountingForInFlightHtlcs<'a, S: Score> {
-       scorer: S,
+pub struct ScorerAccountingForInFlightHtlcs<'a, S: Score<ScoreParams = SP>, SP: Sized> {
+       scorer: &'a mut S,
        // Maps a channel's short channel id and its direction to the liquidity used up.
        inflight_htlcs: &'a InFlightHtlcs,
 }
 
-impl<'a, S: Score> ScorerAccountingForInFlightHtlcs<'a, S> {
+impl<'a, S: Score<ScoreParams = SP>, SP: Sized> ScorerAccountingForInFlightHtlcs<'a, S, SP> {
        /// Initialize a new `ScorerAccountingForInFlightHtlcs`.
-       pub fn new(scorer: S, inflight_htlcs: &'a InFlightHtlcs) -> Self {
+       pub fn new(scorer: &'a mut S, inflight_htlcs: &'a InFlightHtlcs) -> Self {
                ScorerAccountingForInFlightHtlcs {
                        scorer,
                        inflight_htlcs
@@ -121,11 +129,11 @@ impl<'a, S: Score> ScorerAccountingForInFlightHtlcs<'a, S> {
 }
 
 #[cfg(c_bindings)]
-impl<'a, S: Score> Writeable for ScorerAccountingForInFlightHtlcs<'a, S> {
+impl<'a, S: Score<ScoreParams = SP>, SP: Sized> Writeable for ScorerAccountingForInFlightHtlcs<'a, S, SP> {
        fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> { self.scorer.write(writer) }
 }
 
-impl<'a, S: Score> Score for ScorerAccountingForInFlightHtlcs<'a, S> {
+impl<'a, S: Score<ScoreParams = SP>, SP: Sized> Score for ScorerAccountingForInFlightHtlcs<'a, S, SP>  {
        type ScoreParams = S::ScoreParams;
        fn channel_penalty_msat(&self, short_channel_id: u64, source: &NodeId, target: &NodeId, usage: ChannelUsage, score_params: &Self::ScoreParams) -> u64 {
                if let Some(used_liquidity) = self.inflight_htlcs.used_liquidity_msat(
@@ -204,6 +212,15 @@ impl InFlightHtlcs {
                }
        }
 
+       /// Adds a known HTLC given the public key of the HTLC source, target, and short channel
+       /// id.
+       pub fn add_inflight_htlc(&mut self, source: &NodeId, target: &NodeId, channel_scid: u64, used_msat: u64){
+               self.0
+                       .entry((channel_scid, source < target))
+                       .and_modify(|used_liquidity_msat| *used_liquidity_msat += used_msat)
+                       .or_insert(used_msat);
+       }
+
        /// Returns liquidity in msat given the public key of the HTLC source, target, and short channel
        /// id.
        pub fn used_liquidity_msat(&self, source: &NodeId, target: &NodeId, channel_scid: u64) -> Option<u64> {
@@ -262,9 +279,9 @@ impl_writeable_tlv_based!(RouteHop, {
 });
 
 /// The blinded portion of a [`Path`], if we're routing to a recipient who provided blinded paths in
-/// their BOLT12 [`Invoice`].
+/// their [`Bolt12Invoice`].
 ///
-/// [`Invoice`]: crate::offers::invoice::Invoice
+/// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
 pub struct BlindedTail {
        /// The hops of the [`BlindedPath`] provided by the recipient.
@@ -283,7 +300,7 @@ pub struct BlindedTail {
 }
 
 impl_writeable_tlv_based!(BlindedTail, {
-       (0, hops, vec_type),
+       (0, hops, required_vec),
        (2, blinding_point, required),
        (4, excess_final_cltv_expiry_delta, required),
        (6, final_value_msat, required),
@@ -337,11 +354,9 @@ pub struct Route {
        /// [`BlindedTail`]s are present, then the pubkey of the last [`RouteHop`] in each path must be
        /// the same.
        pub paths: Vec<Path>,
-       /// The `payment_params` parameter passed to [`find_route`].
-       /// This is used by `ChannelManager` to track information which may be required for retries,
-       /// provided back to you via [`Event::PaymentPathFailed`].
+       /// The `payment_params` parameter passed via [`RouteParameters`] to [`find_route`].
        ///
-       /// [`Event::PaymentPathFailed`]: crate::events::Event::PaymentPathFailed
+       /// This is used by `ChannelManager` to track information which may be required for retries.
        pub payment_params: Option<PaymentParameters>,
 }
 
@@ -349,7 +364,7 @@ impl Route {
        /// Returns the total amount of fees paid on this [`Route`].
        ///
        /// This doesn't include any extra payment made to the recipient, which can happen in excess of
-       /// the amount passed to [`find_route`]'s `params.final_value_msat`.
+       /// the amount passed to [`find_route`]'s `route_params.final_value_msat`.
        pub fn get_total_fees(&self) -> u64 {
                self.paths.iter().map(|path| path.fee_msat()).sum()
        }
@@ -417,7 +432,7 @@ impl Readable for Route {
                let blinded_tails = blinded_tails.unwrap_or(Vec::new());
                if blinded_tails.len() != 0 {
                        if blinded_tails.len() != paths.len() { return Err(DecodeError::InvalidValue) }
-                       for (mut path, blinded_tail_opt) in paths.iter_mut().zip(blinded_tails.into_iter()) {
+                       for (path, blinded_tail_opt) in paths.iter_mut().zip(blinded_tails.into_iter()) {
                                path.blinded_tail = blinded_tail_opt;
                        }
                }
@@ -427,10 +442,7 @@ impl Readable for Route {
 
 /// Parameters needed to find a [`Route`].
 ///
-/// Passed to [`find_route`] and [`build_route_from_hops`], but also provided in
-/// [`Event::PaymentPathFailed`].
-///
-/// [`Event::PaymentPathFailed`]: crate::events::Event::PaymentPathFailed
+/// Passed to [`find_route`] and [`build_route_from_hops`].
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub struct RouteParameters {
        /// The parameters of the failed payment path.
@@ -481,6 +493,8 @@ pub const DEFAULT_MAX_TOTAL_CLTV_EXPIRY_DELTA: u32 = 1008;
 // limits, but for now more than 10 paths likely carries too much one-path failure.
 pub const DEFAULT_MAX_PATH_COUNT: u8 = 10;
 
+const DEFAULT_MAX_CHANNEL_SATURATION_POW_HALF: u8 = 2;
+
 // The median hop CLTV expiry delta currently seen in the network.
 const MEDIAN_HOP_CLTV_EXPIRY_DELTA: u32 = 40;
 
@@ -548,10 +562,10 @@ impl Writeable for PaymentParameters {
                        (1, self.max_total_cltv_expiry_delta, required),
                        (2, self.payee.features(), option),
                        (3, self.max_path_count, required),
-                       (4, *clear_hints, vec_type),
+                       (4, *clear_hints, required_vec),
                        (5, self.max_channel_saturation_power_of_half, required),
                        (6, self.expiry_time, option),
-                       (7, self.previously_failed_channels, vec_type),
+                       (7, self.previously_failed_channels, required_vec),
                        (8, *blinded_hints, optional_vec),
                        (9, self.payee.final_cltv_expiry_delta(), option),
                });
@@ -566,14 +580,13 @@ impl ReadableArgs<u32> for PaymentParameters {
                        (1, max_total_cltv_expiry_delta, (default_value, DEFAULT_MAX_TOTAL_CLTV_EXPIRY_DELTA)),
                        (2, features, (option: ReadableArgs, payee_pubkey.is_some())),
                        (3, max_path_count, (default_value, DEFAULT_MAX_PATH_COUNT)),
-                       (4, route_hints, vec_type),
-                       (5, max_channel_saturation_power_of_half, (default_value, 2)),
+                       (4, clear_route_hints, required_vec),
+                       (5, max_channel_saturation_power_of_half, (default_value, DEFAULT_MAX_CHANNEL_SATURATION_POW_HALF)),
                        (6, expiry_time, option),
-                       (7, previously_failed_channels, vec_type),
+                       (7, previously_failed_channels, optional_vec),
                        (8, blinded_route_hints, optional_vec),
                        (9, final_cltv_expiry_delta, (default_value, default_final_cltv_expiry_delta)),
                });
-               let clear_route_hints = route_hints.unwrap_or(vec![]);
                let blinded_route_hints = blinded_route_hints.unwrap_or(vec![]);
                let payee = if blinded_route_hints.len() != 0 {
                        if clear_route_hints.len() != 0 || payee_pubkey.is_some() { return Err(DecodeError::InvalidValue) }
@@ -612,7 +625,7 @@ impl PaymentParameters {
                        expiry_time: None,
                        max_total_cltv_expiry_delta: DEFAULT_MAX_TOTAL_CLTV_EXPIRY_DELTA,
                        max_path_count: DEFAULT_MAX_PATH_COUNT,
-                       max_channel_saturation_power_of_half: 2,
+                       max_channel_saturation_power_of_half: DEFAULT_MAX_CHANNEL_SATURATION_POW_HALF,
                        previously_failed_channels: Vec::new(),
                }
        }
@@ -621,15 +634,56 @@ impl PaymentParameters {
        ///
        /// The `final_cltv_expiry_delta` should match the expected final CLTV delta the recipient has
        /// provided.
-       pub fn for_keysend(payee_pubkey: PublicKey, final_cltv_expiry_delta: u32) -> Self {
-               Self::from_node_id(payee_pubkey, final_cltv_expiry_delta).with_bolt11_features(InvoiceFeatures::for_keysend()).expect("PaymentParameters::from_node_id should always initialize the payee as unblinded")
+       ///
+       /// Note that MPP keysend is not widely supported yet. The `allow_mpp` lets you choose
+       /// whether your router will be allowed to find a multi-part route for this payment. If you
+       /// set `allow_mpp` to true, you should ensure a payment secret is set on send, likely via
+       /// [`RecipientOnionFields::secret_only`].
+       ///
+       /// [`RecipientOnionFields::secret_only`]: crate::ln::channelmanager::RecipientOnionFields::secret_only
+       pub fn for_keysend(payee_pubkey: PublicKey, final_cltv_expiry_delta: u32, allow_mpp: bool) -> Self {
+               Self::from_node_id(payee_pubkey, final_cltv_expiry_delta)
+                       .with_bolt11_features(Bolt11InvoiceFeatures::for_keysend(allow_mpp))
+                       .expect("PaymentParameters::from_node_id should always initialize the payee as unblinded")
+       }
+
+       /// Creates parameters for paying to a blinded payee from the provided invoice. Sets
+       /// [`Payee::Blinded::route_hints`], [`Payee::Blinded::features`], and
+       /// [`PaymentParameters::expiry_time`].
+       pub fn from_bolt12_invoice(invoice: &Bolt12Invoice) -> Self {
+               Self::blinded(invoice.payment_paths().to_vec())
+                       .with_bolt12_features(invoice.features().clone()).unwrap()
+                       .with_expiry_time(invoice.created_at().as_secs().saturating_add(invoice.relative_expiry().as_secs()))
        }
 
-       /// Includes the payee's features. Errors if the parameters were initialized with blinded payment
-       /// paths.
+       fn blinded(blinded_route_hints: Vec<(BlindedPayInfo, BlindedPath)>) -> Self {
+               Self {
+                       payee: Payee::Blinded { route_hints: blinded_route_hints, features: None },
+                       expiry_time: None,
+                       max_total_cltv_expiry_delta: DEFAULT_MAX_TOTAL_CLTV_EXPIRY_DELTA,
+                       max_path_count: DEFAULT_MAX_PATH_COUNT,
+                       max_channel_saturation_power_of_half: DEFAULT_MAX_CHANNEL_SATURATION_POW_HALF,
+                       previously_failed_channels: Vec::new(),
+               }
+       }
+
+       /// Includes the payee's features. Errors if the parameters were not initialized with
+       /// [`PaymentParameters::from_bolt12_invoice`].
        ///
        /// This is not exported to bindings users since bindings don't support move semantics
-       pub fn with_bolt11_features(self, features: InvoiceFeatures) -> Result<Self, ()> {
+       pub fn with_bolt12_features(self, features: Bolt12InvoiceFeatures) -> Result<Self, ()> {
+               match self.payee {
+                       Payee::Clear { .. } => Err(()),
+                       Payee::Blinded { route_hints, .. } =>
+                               Ok(Self { payee: Payee::Blinded { route_hints, features: Some(features) }, ..self })
+               }
+       }
+
+       /// Includes the payee's features. Errors if the parameters were initialized with
+       /// [`PaymentParameters::from_bolt12_invoice`].
+       ///
+       /// This is not exported to bindings users since bindings don't support move semantics
+       pub fn with_bolt11_features(self, features: Bolt11InvoiceFeatures) -> Result<Self, ()> {
                match self.payee {
                        Payee::Blinded { .. } => Err(()),
                        Payee::Clear { route_hints, node_id, final_cltv_expiry_delta, .. } =>
@@ -642,7 +696,7 @@ impl PaymentParameters {
        }
 
        /// Includes hints for routing to the payee. Errors if the parameters were initialized with
-       /// blinded payment paths.
+       /// [`PaymentParameters::from_bolt12_invoice`].
        ///
        /// This is not exported to bindings users since bindings don't support move semantics
        pub fn with_route_hints(self, route_hints: Vec<RouteHint>) -> Result<Self, ()> {
@@ -678,7 +732,8 @@ impl PaymentParameters {
                Self { max_path_count, ..self }
        }
 
-       /// Includes a limit for the maximum number of payment paths that may be used.
+       /// Includes a limit for the maximum share of a channel's total capacity that can be sent over, as
+       /// a power of 1/2. See [`PaymentParameters::max_channel_saturation_power_of_half`].
        ///
        /// This is not exported to bindings users since bindings don't support move semantics
        pub fn with_max_channel_saturation_power_of_half(self, max_channel_saturation_power_of_half: u8) -> Self {
@@ -714,7 +769,7 @@ pub enum Payee {
                /// does not contain any features.
                ///
                /// [`for_keysend`]: PaymentParameters::for_keysend
-               features: Option<InvoiceFeatures>,
+               features: Option<Bolt11InvoiceFeatures>,
                /// The minimum CLTV delta at the end of the route. This value must not be zero.
                final_cltv_expiry_delta: u32,
        },
@@ -751,14 +806,27 @@ impl Payee {
                        _ => None,
                }
        }
+       fn blinded_route_hints(&self) -> &[(BlindedPayInfo, BlindedPath)] {
+               match self {
+                       Self::Blinded { route_hints, .. } => &route_hints[..],
+                       Self::Clear { .. } => &[]
+               }
+       }
+
+       fn unblinded_route_hints(&self) -> &[RouteHint] {
+               match self {
+                       Self::Blinded { .. } => &[],
+                       Self::Clear { route_hints, .. } => &route_hints[..]
+               }
+       }
 }
 
 enum FeaturesRef<'a> {
-       Bolt11(&'a InvoiceFeatures),
+       Bolt11(&'a Bolt11InvoiceFeatures),
        Bolt12(&'a Bolt12InvoiceFeatures),
 }
 enum Features {
-       Bolt11(InvoiceFeatures),
+       Bolt11(Bolt11InvoiceFeatures),
        Bolt12(Bolt12InvoiceFeatures),
 }
 
@@ -769,7 +837,7 @@ impl Features {
                        _ => None,
                }
        }
-       fn bolt11(self) -> Option<InvoiceFeatures> {
+       fn bolt11(self) -> Option<Bolt11InvoiceFeatures> {
                match self {
                        Self::Bolt11(f) => Some(f),
                        _ => None,
@@ -895,18 +963,34 @@ enum CandidateRouteHop<'a> {
                info: DirectedChannelInfo<'a>,
                short_channel_id: u64,
        },
-       /// A hop to the payee found in the payment invoice, though not necessarily a direct channel.
+       /// A hop to the payee found in the BOLT 11 payment invoice, though not necessarily a direct
+       /// channel.
        PrivateHop {
                hint: &'a RouteHintHop,
-       }
+       },
+       /// The payee's identity is concealed behind blinded paths provided in a BOLT 12 invoice.
+       Blinded {
+               hint: &'a (BlindedPayInfo, BlindedPath),
+               hint_idx: usize,
+       },
+       /// Similar to [`Self::Blinded`], but the path here has 1 blinded hop. `BlindedPayInfo` provided
+       /// for 1-hop blinded paths is ignored because it is meant to apply to the hops *between* the
+       /// introduction node and the destination. Useful for tracking that we need to include a blinded
+       /// path at the end of our [`Route`].
+       OneHopBlinded {
+               hint: &'a (BlindedPayInfo, BlindedPath),
+               hint_idx: usize,
+       },
 }
 
 impl<'a> CandidateRouteHop<'a> {
-       fn short_channel_id(&self) -> u64 {
+       fn short_channel_id(&self) -> Option<u64> {
                match self {
-                       CandidateRouteHop::FirstHop { details } => details.get_outbound_payment_scid().unwrap(),
-                       CandidateRouteHop::PublicHop { short_channel_id, .. } => *short_channel_id,
-                       CandidateRouteHop::PrivateHop { hint } => hint.short_channel_id,
+                       CandidateRouteHop::FirstHop { details } => Some(details.get_outbound_payment_scid().unwrap()),
+                       CandidateRouteHop::PublicHop { short_channel_id, .. } => Some(*short_channel_id),
+                       CandidateRouteHop::PrivateHop { hint } => Some(hint.short_channel_id),
+                       CandidateRouteHop::Blinded { .. } => None,
+                       CandidateRouteHop::OneHopBlinded { .. } => None,
                }
        }
 
@@ -916,6 +1000,8 @@ impl<'a> CandidateRouteHop<'a> {
                        CandidateRouteHop::FirstHop { details } => details.counterparty.features.to_context(),
                        CandidateRouteHop::PublicHop { info, .. } => info.channel().features.clone(),
                        CandidateRouteHop::PrivateHop { .. } => ChannelFeatures::empty(),
+                       CandidateRouteHop::Blinded { .. } => ChannelFeatures::empty(),
+                       CandidateRouteHop::OneHopBlinded { .. } => ChannelFeatures::empty(),
                }
        }
 
@@ -924,14 +1010,18 @@ impl<'a> CandidateRouteHop<'a> {
                        CandidateRouteHop::FirstHop { .. } => 0,
                        CandidateRouteHop::PublicHop { info, .. } => info.direction().cltv_expiry_delta as u32,
                        CandidateRouteHop::PrivateHop { hint } => hint.cltv_expiry_delta as u32,
+                       CandidateRouteHop::Blinded { hint, .. } => hint.0.cltv_expiry_delta as u32,
+                       CandidateRouteHop::OneHopBlinded { .. } => 0,
                }
        }
 
        fn htlc_minimum_msat(&self) -> u64 {
                match self {
-                       CandidateRouteHop::FirstHop { .. } => 0,
+                       CandidateRouteHop::FirstHop { details } => details.next_outbound_htlc_minimum_msat,
                        CandidateRouteHop::PublicHop { info, .. } => info.direction().htlc_minimum_msat,
                        CandidateRouteHop::PrivateHop { hint } => hint.htlc_minimum_msat.unwrap_or(0),
+                       CandidateRouteHop::Blinded { hint, .. } => hint.0.htlc_minimum_msat,
+                       CandidateRouteHop::OneHopBlinded { .. } => 0,
                }
        }
 
@@ -942,6 +1032,14 @@ impl<'a> CandidateRouteHop<'a> {
                        },
                        CandidateRouteHop::PublicHop { info, .. } => info.direction().fees,
                        CandidateRouteHop::PrivateHop { hint } => hint.fees,
+                       CandidateRouteHop::Blinded { hint, .. } => {
+                               RoutingFees {
+                                       base_msat: hint.0.fee_base_msat,
+                                       proportional_millionths: hint.0.fee_proportional_millionths
+                               }
+                       },
+                       CandidateRouteHop::OneHopBlinded { .. } =>
+                               RoutingFees { base_msat: 0, proportional_millionths: 0 },
                }
        }
 
@@ -951,11 +1049,41 @@ impl<'a> CandidateRouteHop<'a> {
                                liquidity_msat: details.next_outbound_htlc_limit_msat,
                        },
                        CandidateRouteHop::PublicHop { info, .. } => info.effective_capacity(),
-                       CandidateRouteHop::PrivateHop { .. } => EffectiveCapacity::Infinite,
+                       CandidateRouteHop::PrivateHop { hint: RouteHintHop { htlc_maximum_msat: Some(max), .. }} =>
+                               EffectiveCapacity::HintMaxHTLC { amount_msat: *max },
+                       CandidateRouteHop::PrivateHop { hint: RouteHintHop { htlc_maximum_msat: None, .. }} =>
+                               EffectiveCapacity::Infinite,
+                       CandidateRouteHop::Blinded { hint, .. } =>
+                               EffectiveCapacity::HintMaxHTLC { amount_msat: hint.0.htlc_maximum_msat },
+                       CandidateRouteHop::OneHopBlinded { .. } => EffectiveCapacity::Infinite,
+               }
+       }
+
+       fn id(&self, channel_direction: bool /* src_node_id < target_node_id */) -> CandidateHopId {
+               match self {
+                       CandidateRouteHop::Blinded { hint_idx, .. } => CandidateHopId::Blinded(*hint_idx),
+                       CandidateRouteHop::OneHopBlinded { hint_idx, .. } => CandidateHopId::Blinded(*hint_idx),
+                       _ => CandidateHopId::Clear((self.short_channel_id().unwrap(), channel_direction)),
+               }
+       }
+       fn blinded_path(&self) -> Option<&'a BlindedPath> {
+               match self {
+                       CandidateRouteHop::Blinded { hint, .. } | CandidateRouteHop::OneHopBlinded { hint, .. } => {
+                               Some(&hint.1)
+                       },
+                       _ => None,
                }
        }
 }
 
+#[derive(Clone, Copy, Eq, Hash, Ord, PartialOrd, PartialEq)]
+enum CandidateHopId {
+       /// Contains (scid, src_node_id < target_node_id)
+       Clear((u64, bool)),
+       /// Index of the blinded route hint in [`Payee::Blinded::route_hints`].
+       Blinded(usize),
+}
+
 #[inline]
 fn max_htlc_from_capacity(capacity: EffectiveCapacity, max_channel_saturation_power_of_half: u8) -> u64 {
        let saturation_shift: u32 = max_channel_saturation_power_of_half as u32;
@@ -963,8 +1091,11 @@ fn max_htlc_from_capacity(capacity: EffectiveCapacity, max_channel_saturation_po
                EffectiveCapacity::ExactLiquidity { liquidity_msat } => liquidity_msat,
                EffectiveCapacity::Infinite => u64::max_value(),
                EffectiveCapacity::Unknown => EffectiveCapacity::Unknown.as_msat(),
-               EffectiveCapacity::MaximumHTLC { amount_msat } =>
+               EffectiveCapacity::AdvertisedMaxHTLC { amount_msat } =>
                        amount_msat.checked_shr(saturation_shift).unwrap_or(0),
+               // Treat htlc_maximum_msat from a route hint as an exact liquidity amount, since the invoice is
+               // expected to have been generated from up-to-date capacity information.
+               EffectiveCapacity::HintMaxHTLC { amount_msat } => amount_msat,
                EffectiveCapacity::Total { capacity_msat, htlc_maximum_msat } =>
                        cmp::min(capacity_msat.checked_shr(saturation_shift).unwrap_or(0), htlc_maximum_msat),
        }
@@ -1101,7 +1232,7 @@ impl<'a> PaymentPath<'a> {
                                cur_hop_fees_msat = self.hops.get(i + 1).unwrap().0.hop_use_fee_msat;
                        }
 
-                       let mut cur_hop = &mut self.hops.get_mut(i).unwrap().0;
+                       let cur_hop = &mut self.hops.get_mut(i).unwrap().0;
                        cur_hop.next_hops_fee_msat = total_fee_paid_msat;
                        // Overpay in fees if we can't save these funds due to htlc_minimum_msat.
                        // We try to account for htlc_minimum_msat in scoring (add_entry!), so that nodes don't
@@ -1192,12 +1323,75 @@ impl fmt::Display for LoggedPayeePubkey {
        }
 }
 
+struct LoggedCandidateHop<'a>(&'a CandidateRouteHop<'a>);
+impl<'a> fmt::Display for LoggedCandidateHop<'a> {
+       fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+               match self.0 {
+                       CandidateRouteHop::Blinded { hint, .. } | CandidateRouteHop::OneHopBlinded { hint, .. } => {
+                               "blinded route hint with introduction node id ".fmt(f)?;
+                               hint.1.introduction_node_id.fmt(f)?;
+                               " and blinding point ".fmt(f)?;
+                               hint.1.blinding_point.fmt(f)
+                       },
+                       CandidateRouteHop::FirstHop { .. } => {
+                               "first hop with SCID ".fmt(f)?;
+                               self.0.short_channel_id().unwrap().fmt(f)
+                       },
+                       CandidateRouteHop::PrivateHop { .. } => {
+                               "route hint with SCID ".fmt(f)?;
+                               self.0.short_channel_id().unwrap().fmt(f)
+                       },
+                       _ => {
+                               "SCID ".fmt(f)?;
+                               self.0.short_channel_id().unwrap().fmt(f)
+                       },
+               }
+       }
+}
+
+#[inline]
+fn sort_first_hop_channels(
+       channels: &mut Vec<&ChannelDetails>, used_liquidities: &HashMap<CandidateHopId, u64>,
+       recommended_value_msat: u64, our_node_pubkey: &PublicKey
+) {
+       // Sort the first_hops channels to the same node(s) in priority order of which channel we'd
+       // most like to use.
+       //
+       // First, if channels are below `recommended_value_msat`, sort them in descending order,
+       // preferring larger channels to avoid splitting the payment into more MPP parts than is
+       // required.
+       //
+       // Second, because simply always sorting in descending order would always use our largest
+       // available outbound capacity, needlessly fragmenting our available channel capacities,
+       // sort channels above `recommended_value_msat` in ascending order, preferring channels
+       // which have enough, but not too much, capacity for the payment.
+       //
+       // Available outbound balances factor in liquidity already reserved for previously found paths.
+       channels.sort_unstable_by(|chan_a, chan_b| {
+               let chan_a_outbound_limit_msat = chan_a.next_outbound_htlc_limit_msat
+                       .saturating_sub(*used_liquidities.get(&CandidateHopId::Clear((chan_a.get_outbound_payment_scid().unwrap(),
+                       our_node_pubkey < &chan_a.counterparty.node_id))).unwrap_or(&0));
+               let chan_b_outbound_limit_msat = chan_b.next_outbound_htlc_limit_msat
+                       .saturating_sub(*used_liquidities.get(&CandidateHopId::Clear((chan_b.get_outbound_payment_scid().unwrap(),
+                       our_node_pubkey < &chan_b.counterparty.node_id))).unwrap_or(&0));
+               if chan_b_outbound_limit_msat < recommended_value_msat || chan_a_outbound_limit_msat < recommended_value_msat {
+                       // Sort in descending order
+                       chan_b_outbound_limit_msat.cmp(&chan_a_outbound_limit_msat)
+               } else {
+                       // Sort in ascending order
+                       chan_a_outbound_limit_msat.cmp(&chan_b_outbound_limit_msat)
+               }
+       });
+}
+
 /// Finds a route from us (payer) to the given target node (payee).
 ///
-/// If the payee provided features in their invoice, they should be provided via `params.payee`.
+/// If the payee provided features in their invoice, they should be provided via the `payee` field
+/// in the given [`RouteParameters::payment_params`].
 /// Without this, MPP will only be used if the payee's features are available in the network graph.
 ///
-/// Private routing paths between a public node and the target may be included in `params.payee`.
+/// Private routing paths between a public node and the target may be included in the `payee` field
+/// of [`RouteParameters::payment_params`].
 ///
 /// If some channels aren't announced, it may be useful to fill in `first_hops` with the results
 /// from [`ChannelManager::list_usable_channels`]. If it is filled in, the view of these channels
@@ -1207,15 +1401,9 @@ impl fmt::Display for LoggedPayeePubkey {
 /// However, the enabled/disabled bit on such channels as well as the `htlc_minimum_msat` /
 /// `htlc_maximum_msat` *are* checked as they may change based on the receiving node.
 ///
-/// # Note
-///
-/// May be used to re-compute a [`Route`] when handling a [`Event::PaymentPathFailed`]. Any
-/// adjustments to the [`NetworkGraph`] and channel scores should be made prior to calling this
-/// function.
-///
 /// # Panics
 ///
-/// Panics if first_hops contains channels without short_channel_ids;
+/// Panics if first_hops contains channels without `short_channel_id`s;
 /// [`ChannelManager::list_usable_channels`] will never include such channels.
 ///
 /// [`ChannelManager::list_usable_channels`]: crate::ln::channelmanager::ChannelManager::list_usable_channels
@@ -1245,7 +1433,7 @@ where L::Target: Logger {
        // unblinded payee id as an option. We also need a non-optional "payee id" for path construction,
        // so use a dummy id for this in the blinded case.
        let payee_node_id_opt = payment_params.payee.node_id().map(|pk| NodeId::from_pubkey(&pk));
-       const DUMMY_BLINDED_PAYEE_ID: [u8; 33] = [42u8; 33];
+       const DUMMY_BLINDED_PAYEE_ID: [u8; 33] = [2; 33];
        let maybe_dummy_payee_pk = payment_params.payee.node_id().unwrap_or_else(|| PublicKey::from_slice(&DUMMY_BLINDED_PAYEE_ID).unwrap());
        let maybe_dummy_payee_node_id = NodeId::from_pubkey(&maybe_dummy_payee_pk);
        let our_node_id = NodeId::from_pubkey(&our_node_pubkey);
@@ -1272,8 +1460,23 @@ where L::Target: Logger {
                                }
                        }
                },
-               _ => return Err(LightningError{err: "Routing to blinded paths isn't supported yet".to_owned(), action: ErrorAction::IgnoreError}),
-
+               Payee::Blinded { route_hints, .. } => {
+                       if route_hints.iter().all(|(_, path)| &path.introduction_node_id == our_node_pubkey) {
+                               return Err(LightningError{err: "Cannot generate a route to blinded paths if we are the introduction node to all of them".to_owned(), action: ErrorAction::IgnoreError});
+                       }
+                       for (_, blinded_path) in route_hints.iter() {
+                               if blinded_path.blinded_hops.len() == 0 {
+                                       return Err(LightningError{err: "0-hop blinded path provided".to_owned(), action: ErrorAction::IgnoreError});
+                               } else if &blinded_path.introduction_node_id == our_node_pubkey {
+                                       log_info!(logger, "Got blinded path with ourselves as the introduction node, ignoring");
+                               } else if blinded_path.blinded_hops.len() == 1 &&
+                                       route_hints.iter().any( |(_, p)| p.blinded_hops.len() == 1
+                                               && p.introduction_node_id != blinded_path.introduction_node_id)
+                               {
+                                       return Err(LightningError{err: format!("1-hop blinded paths must all have matching introduction node ids"), action: ErrorAction::IgnoreError});
+                               }
+                       }
+               }
        }
        let final_cltv_expiry_delta = payment_params.payee.final_cltv_expiry_delta().unwrap_or(0);
        if payment_params.max_total_cltv_expiry_delta <= final_cltv_expiry_delta {
@@ -1425,11 +1628,12 @@ where L::Target: Logger {
        // drop the requirement by setting this to 0.
        let mut channel_saturation_pow_half = payment_params.max_channel_saturation_power_of_half;
 
-       // Keep track of how much liquidity has been used in selected channels. Used to determine
-       // if the channel can be used by additional MPP paths or to inform path finding decisions. It is
-       // aware of direction *only* to ensure that the correct htlc_maximum_msat value is used. Hence,
-       // liquidity used in one direction will not offset any used in the opposite direction.
-       let mut used_channel_liquidities: HashMap<(u64, bool), u64> =
+       // Keep track of how much liquidity has been used in selected channels or blinded paths. Used to
+       // determine if the channel can be used by additional MPP paths or to inform path finding
+       // decisions. It is aware of direction *only* to ensure that the correct htlc_maximum_msat value
+       // is used. Hence, liquidity used in one direction will not offset any used in the opposite
+       // direction.
+       let mut used_liquidities: HashMap<CandidateHopId, u64> =
                HashMap::with_capacity(network_nodes.len());
 
        // Keeping track of how much value we already collected across other paths. Helps to decide
@@ -1437,31 +1641,19 @@ where L::Target: Logger {
        let mut already_collected_value_msat = 0;
 
        for (_, channels) in first_hop_targets.iter_mut() {
-               // Sort the first_hops channels to the same node(s) in priority order of which channel we'd
-               // most like to use.
-               //
-               // First, if channels are below `recommended_value_msat`, sort them in descending order,
-               // preferring larger channels to avoid splitting the payment into more MPP parts than is
-               // required.
-               //
-               // Second, because simply always sorting in descending order would always use our largest
-               // available outbound capacity, needlessly fragmenting our available channel capacities,
-               // sort channels above `recommended_value_msat` in ascending order, preferring channels
-               // which have enough, but not too much, capacity for the payment.
-               channels.sort_unstable_by(|chan_a, chan_b| {
-                       if chan_b.next_outbound_htlc_limit_msat < recommended_value_msat || chan_a.next_outbound_htlc_limit_msat < recommended_value_msat {
-                               // Sort in descending order
-                               chan_b.next_outbound_htlc_limit_msat.cmp(&chan_a.next_outbound_htlc_limit_msat)
-                       } else {
-                               // Sort in ascending order
-                               chan_a.next_outbound_htlc_limit_msat.cmp(&chan_b.next_outbound_htlc_limit_msat)
-                       }
-               });
+               sort_first_hop_channels(channels, &used_liquidities, recommended_value_msat,
+                       our_node_pubkey);
        }
 
        log_trace!(logger, "Building path from {} to payer {} for value {} msat.",
                LoggedPayeePubkey(payment_params.payee.node_id()), our_node_pubkey, final_value_msat);
 
+       // Remember how many candidates we ignored to allow for some logging afterwards.
+       let mut num_ignored_value_contribution = 0;
+       let mut num_ignored_path_length_limit = 0;
+       let mut num_ignored_cltv_delta_limit = 0;
+       let mut num_ignored_previously_failed = 0;
+
        macro_rules! add_entry {
                // 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,
@@ -1470,14 +1662,15 @@ where L::Target: Logger {
                ( $candidate: expr, $src_node_id: expr, $dest_node_id: expr, $next_hops_fee_msat: expr,
                        $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr,
                        $next_hops_path_penalty_msat: expr, $next_hops_cltv_delta: expr, $next_hops_path_length: expr ) => { {
-                       // We "return" whether we updated the path at the end, via this:
-                       let mut did_add_update_path_to_src_node = false;
+                       // We "return" whether we updated the path at the end, and how much we can route via
+                       // this channel, via this:
+                       let mut did_add_update_path_to_src_node = None;
                        // Channels to self should not be used. This is more of belt-and-suspenders, because in
                        // practice these cases should be caught earlier:
                        // - for regular channels at channel announcement (TODO)
                        // - for first and last hops early in get_route
                        if $src_node_id != $dest_node_id {
-                               let short_channel_id = $candidate.short_channel_id();
+                               let scid_opt = $candidate.short_channel_id();
                                let effective_capacity = $candidate.effective_capacity();
                                let htlc_maximum_msat = max_htlc_from_capacity(effective_capacity, channel_saturation_pow_half);
 
@@ -1489,8 +1682,8 @@ where L::Target: Logger {
                                // if the amount being transferred over this path is lower.
                                // We do this for now, but this is a subject for removal.
                                if let Some(mut available_value_contribution_msat) = htlc_maximum_msat.checked_sub($next_hops_fee_msat) {
-                                       let used_liquidity_msat = used_channel_liquidities
-                                               .get(&(short_channel_id, $src_node_id < $dest_node_id))
+                                       let used_liquidity_msat = used_liquidities
+                                               .get(&$candidate.id($src_node_id < $dest_node_id))
                                                .map_or(0, |used_liquidity_msat| {
                                                        available_value_contribution_msat = available_value_contribution_msat
                                                                .saturating_sub(*used_liquidity_msat);
@@ -1532,16 +1725,40 @@ where L::Target: Logger {
                                                 (amount_to_transfer_over_msat < $next_hops_path_htlc_minimum_msat &&
                                                  recommended_value_msat > $next_hops_path_htlc_minimum_msat));
 
-                                       let payment_failed_on_this_channel =
-                                               payment_params.previously_failed_channels.contains(&short_channel_id);
+                                       let payment_failed_on_this_channel = scid_opt.map_or(false,
+                                               |scid| payment_params.previously_failed_channels.contains(&scid));
+
+                                       let should_log_candidate = match $candidate {
+                                               CandidateRouteHop::FirstHop { .. } => true,
+                                               CandidateRouteHop::PrivateHop { .. } => true,
+                                               CandidateRouteHop::Blinded { .. } => true,
+                                               _ => false,
+                                       };
 
                                        // If HTLC minimum is larger than the amount we're going to transfer, we shouldn't
                                        // bother considering this channel. If retrying with recommended_value_msat may
                                        // allow us to hit the HTLC minimum limit, set htlc_minimum_limit so that we go
                                        // around again with a higher amount.
-                                       if !contributes_sufficient_value || exceeds_max_path_length ||
-                                               exceeds_cltv_delta_limit || payment_failed_on_this_channel {
-                                               // Path isn't useful, ignore it and move on.
+                                       if !contributes_sufficient_value {
+                                               if should_log_candidate {
+                                                       log_trace!(logger, "Ignoring {} due to insufficient value contribution.", LoggedCandidateHop(&$candidate));
+                                               }
+                                               num_ignored_value_contribution += 1;
+                                       } else if exceeds_max_path_length {
+                                               if should_log_candidate {
+                                                       log_trace!(logger, "Ignoring {} due to exceeding maximum path length limit.", LoggedCandidateHop(&$candidate));
+                                               }
+                                               num_ignored_path_length_limit += 1;
+                                       } else if exceeds_cltv_delta_limit {
+                                               if should_log_candidate {
+                                                       log_trace!(logger, "Ignoring {} due to exceeding CLTV delta limit.", LoggedCandidateHop(&$candidate));
+                                               }
+                                               num_ignored_cltv_delta_limit += 1;
+                                       } else if payment_failed_on_this_channel {
+                                               if should_log_candidate {
+                                                       log_trace!(logger, "Ignoring {} due to a failed previous payment attempt.", LoggedCandidateHop(&$candidate));
+                                               }
+                                               num_ignored_previously_failed += 1;
                                        } else if may_overpay_to_meet_path_minimum_msat {
                                                hit_minimum_limit = true;
                                        } else if over_path_minimum_msat {
@@ -1602,9 +1819,9 @@ where L::Target: Logger {
                                                                inflight_htlc_msat: used_liquidity_msat,
                                                                effective_capacity,
                                                        };
-                                                       let channel_penalty_msat = scorer.channel_penalty_msat(
-                                                               short_channel_id, &$src_node_id, &$dest_node_id, channel_usage, score_params
-                                                       );
+                                                       let channel_penalty_msat = scid_opt.map_or(0,
+                                                               |scid| scorer.channel_penalty_msat(scid, &$src_node_id, &$dest_node_id,
+                                                                       channel_usage, score_params));
                                                        let path_penalty_msat = $next_hops_path_penalty_msat
                                                                .saturating_add(channel_penalty_msat);
                                                        let new_graph_node = RouteGraphNode {
@@ -1652,7 +1869,7 @@ where L::Target: Logger {
                                                                {
                                                                        old_entry.value_contribution_msat = value_contribution_msat;
                                                                }
-                                                               did_add_update_path_to_src_node = true;
+                                                               did_add_update_path_to_src_node = Some(value_contribution_msat);
                                                        } else if old_entry.was_processed && new_cost < old_cost {
                                                                #[cfg(all(not(ldk_bench), any(test, fuzzing)))]
                                                                {
@@ -1761,7 +1978,7 @@ where L::Target: Logger {
 
        // TODO: diversify by nodes (so that all paths aren't doomed if one node is offline).
        'paths_collection: loop {
-               // For every new path, start from scratch, except for used_channel_liquidities, which
+               // For every new path, start from scratch, except for used_liquidities, which
                // helps to avoid reusing previously selected paths in future iterations.
                targets.clear();
                dist.clear();
@@ -1773,9 +1990,9 @@ where L::Target: Logger {
                        for details in first_channels {
                                let candidate = CandidateRouteHop::FirstHop { details };
                                let added = add_entry!(candidate, our_node_id, payee, 0, path_value_msat,
-                                                                       0, 0u64, 0, 0);
-                               log_trace!(logger, "{} direct route to payee via SCID {}",
-                                               if added { "Added" } else { "Skipped" }, candidate.short_channel_id());
+                                                                       0, 0u64, 0, 0).is_some();
+                               log_trace!(logger, "{} direct route to payee via {}",
+                                               if added { "Added" } else { "Skipped" }, LoggedCandidateHop(&candidate));
                        }
                }));
 
@@ -1796,11 +2013,37 @@ where L::Target: Logger {
                // If a caller provided us with last hops, add them to routing targets. Since this happens
                // earlier than general path finding, they will be somewhat prioritized, although currently
                // it matters only if the fees are exactly the same.
-               let route_hints = match &payment_params.payee {
-                       Payee::Clear { route_hints, .. } => route_hints,
-                       _ => return Err(LightningError{err: "Routing to blinded paths isn't supported yet".to_owned(), action: ErrorAction::IgnoreError}),
-               };
-               for route in route_hints.iter().filter(|route| !route.0.is_empty()) {
+               for (hint_idx, hint) in payment_params.payee.blinded_route_hints().iter().enumerate() {
+                       let intro_node_id = NodeId::from_pubkey(&hint.1.introduction_node_id);
+                       let have_intro_node_in_graph =
+                               // Only add the hops in this route to our candidate set if either
+                               // we have a direct channel to the first hop or the first hop is
+                               // in the regular network graph.
+                               first_hop_targets.get(&intro_node_id).is_some() ||
+                               network_nodes.get(&intro_node_id).is_some();
+                       if !have_intro_node_in_graph { continue }
+                       let candidate = if hint.1.blinded_hops.len() == 1 {
+                               CandidateRouteHop::OneHopBlinded { hint, hint_idx }
+                       } else { CandidateRouteHop::Blinded { hint, hint_idx } };
+                       let mut path_contribution_msat = path_value_msat;
+                       if let Some(hop_used_msat) = add_entry!(candidate, intro_node_id, maybe_dummy_payee_node_id,
+                               0, path_contribution_msat, 0, 0_u64, 0, 0)
+                       {
+                               path_contribution_msat = hop_used_msat;
+                       } else { continue }
+                       if let Some(first_channels) = first_hop_targets.get_mut(&NodeId::from_pubkey(&hint.1.introduction_node_id)) {
+                               sort_first_hop_channels(first_channels, &used_liquidities, recommended_value_msat,
+                                       our_node_pubkey);
+                               for details in first_channels {
+                                       let first_hop_candidate = CandidateRouteHop::FirstHop { details };
+                                       add_entry!(first_hop_candidate, our_node_id, intro_node_id, 0, path_contribution_msat, 0,
+                                               0_u64, 0, 0);
+                               }
+                       }
+               }
+               for route in payment_params.payee.unblinded_route_hints().iter()
+                       .filter(|route| !route.0.is_empty())
+               {
                        let first_hop_in_route = &(route.0)[0];
                        let have_hop_src_in_graph =
                                // Only add the hops in this route to our candidate set if either
@@ -1820,6 +2063,7 @@ where L::Target: Logger {
                                let mut aggregate_next_hops_path_penalty_msat: u64 = 0;
                                let mut aggregate_next_hops_cltv_delta: u32 = 0;
                                let mut aggregate_next_hops_path_length: u8 = 0;
+                               let mut aggregate_path_contribution_msat = path_value_msat;
 
                                for (idx, (hop, prev_hop_id)) in hop_iter.zip(prev_hop_iter).enumerate() {
                                        let source = NodeId::from_pubkey(&hop.src_node_id);
@@ -1833,18 +2077,22 @@ where L::Target: Logger {
                                                })
                                                .unwrap_or_else(|| CandidateRouteHop::PrivateHop { hint: hop });
 
-                                       if !add_entry!(candidate, source, target, aggregate_next_hops_fee_msat,
-                                                               path_value_msat, aggregate_next_hops_path_htlc_minimum_msat,
-                                                               aggregate_next_hops_path_penalty_msat,
-                                                               aggregate_next_hops_cltv_delta, aggregate_next_hops_path_length) {
+                                       if let Some(hop_used_msat) = add_entry!(candidate, source, target,
+                                               aggregate_next_hops_fee_msat, aggregate_path_contribution_msat,
+                                               aggregate_next_hops_path_htlc_minimum_msat, aggregate_next_hops_path_penalty_msat,
+                                               aggregate_next_hops_cltv_delta, aggregate_next_hops_path_length)
+                                       {
+                                               aggregate_path_contribution_msat = hop_used_msat;
+                                       } else {
                                                // If this hop was not used then there is no use checking the preceding
                                                // hops in the RouteHint. We can break by just searching for a direct
                                                // channel between last checked hop and first_hop_targets.
                                                hop_used = false;
                                        }
 
-                                       let used_liquidity_msat = used_channel_liquidities
-                                               .get(&(hop.short_channel_id, source < target)).copied().unwrap_or(0);
+                                       let used_liquidity_msat = used_liquidities
+                                               .get(&candidate.id(source < target)).copied()
+                                               .unwrap_or(0);
                                        let channel_usage = ChannelUsage {
                                                amount_msat: final_value_msat + aggregate_next_hops_fee_msat,
                                                inflight_htlc_msat: used_liquidity_msat,
@@ -1863,14 +2111,15 @@ where L::Target: Logger {
                                                .saturating_add(1);
 
                                        // Searching for a direct channel between last checked hop and first_hop_targets
-                                       if let Some(first_channels) = first_hop_targets.get(&NodeId::from_pubkey(&prev_hop_id)) {
+                                       if let Some(first_channels) = first_hop_targets.get_mut(&NodeId::from_pubkey(&prev_hop_id)) {
+                                               sort_first_hop_channels(first_channels, &used_liquidities,
+                                                       recommended_value_msat, our_node_pubkey);
                                                for details in first_channels {
-                                                       let candidate = CandidateRouteHop::FirstHop { details };
-                                                       add_entry!(candidate, our_node_id, NodeId::from_pubkey(&prev_hop_id),
-                                                               aggregate_next_hops_fee_msat, path_value_msat,
-                                                               aggregate_next_hops_path_htlc_minimum_msat,
-                                                               aggregate_next_hops_path_penalty_msat, aggregate_next_hops_cltv_delta,
-                                                               aggregate_next_hops_path_length);
+                                                       let first_hop_candidate = CandidateRouteHop::FirstHop { details };
+                                                       add_entry!(first_hop_candidate, our_node_id, NodeId::from_pubkey(&prev_hop_id),
+                                                               aggregate_next_hops_fee_msat, aggregate_path_contribution_msat,
+                                                               aggregate_next_hops_path_htlc_minimum_msat, aggregate_next_hops_path_penalty_msat,
+                                                               aggregate_next_hops_cltv_delta, aggregate_next_hops_path_length);
                                                }
                                        }
 
@@ -1903,12 +2152,15 @@ where L::Target: Logger {
                                                // Note that we *must* check if the last hop was added as `add_entry`
                                                // always assumes that the third argument is a node to which we have a
                                                // path.
-                                               if let Some(first_channels) = first_hop_targets.get(&NodeId::from_pubkey(&hop.src_node_id)) {
+                                               if let Some(first_channels) = first_hop_targets.get_mut(&NodeId::from_pubkey(&hop.src_node_id)) {
+                                                       sort_first_hop_channels(first_channels, &used_liquidities,
+                                                               recommended_value_msat, our_node_pubkey);
                                                        for details in first_channels {
-                                                               let candidate = CandidateRouteHop::FirstHop { details };
-                                                               add_entry!(candidate, our_node_id,
+                                                               let first_hop_candidate = CandidateRouteHop::FirstHop { details };
+                                                               add_entry!(first_hop_candidate, our_node_id,
                                                                        NodeId::from_pubkey(&hop.src_node_id),
-                                                                       aggregate_next_hops_fee_msat, path_value_msat,
+                                                                       aggregate_next_hops_fee_msat,
+                                                                       aggregate_path_contribution_msat,
                                                                        aggregate_next_hops_path_htlc_minimum_msat,
                                                                        aggregate_next_hops_path_penalty_msat,
                                                                        aggregate_next_hops_cltv_delta,
@@ -1947,10 +2199,12 @@ where L::Target: Logger {
                                        let mut features_set = false;
                                        if let Some(first_channels) = first_hop_targets.get(&ordered_hops.last().unwrap().0.node_id) {
                                                for details in first_channels {
-                                                       if details.get_outbound_payment_scid().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;
+                                                       if let Some(scid) = ordered_hops.last().unwrap().0.candidate.short_channel_id() {
+                                                               if details.get_outbound_payment_scid().unwrap() == scid {
+                                                                       ordered_hops.last_mut().unwrap().1 = details.counterparty.features.to_context();
+                                                                       features_set = true;
+                                                                       break;
+                                                               }
                                                        }
                                                }
                                        }
@@ -2019,8 +2273,8 @@ where L::Target: Logger {
                                        .chain(payment_path.hops.iter().map(|(hop, _)| &hop.node_id));
                                for (prev_hop, (hop, _)) in prev_hop_iter.zip(payment_path.hops.iter()) {
                                        let spent_on_hop_msat = value_contribution_msat + hop.next_hops_fee_msat;
-                                       let used_liquidity_msat = used_channel_liquidities
-                                               .entry((hop.candidate.short_channel_id(), *prev_hop < hop.node_id))
+                                       let used_liquidity_msat = used_liquidities
+                                               .entry(hop.candidate.id(*prev_hop < hop.node_id))
                                                .and_modify(|used_liquidity_msat| *used_liquidity_msat += spent_on_hop_msat)
                                                .or_insert(spent_on_hop_msat);
                                        let hop_capacity = hop.candidate.effective_capacity();
@@ -2036,11 +2290,12 @@ 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()) / 2].0.candidate.short_channel_id();
+                                       let victim_candidate = &payment_path.hops[(payment_path.hops.len()) / 2].0.candidate;
                                        let exhausted = u64::max_value();
-                                       log_trace!(logger, "Disabling channel {} for future path building iterations to avoid duplicates.", victim_scid);
-                                       *used_channel_liquidities.entry((victim_scid, false)).or_default() = exhausted;
-                                       *used_channel_liquidities.entry((victim_scid, true)).or_default() = exhausted;
+                                       log_trace!(logger, "Disabling route candidate {} for future path building iterations to
+                                               avoid duplicates.", LoggedCandidateHop(victim_candidate));
+                                       *used_liquidities.entry(victim_candidate.id(false)).or_default() = exhausted;
+                                       *used_liquidities.entry(victim_candidate.id(true)).or_default() = exhausted;
                                }
 
                                // Track the total amount all our collected paths allow to send so that we know
@@ -2105,6 +2360,12 @@ where L::Target: Logger {
                }
        }
 
+       let num_ignored_total = num_ignored_value_contribution + num_ignored_path_length_limit +
+               num_ignored_cltv_delta_limit + num_ignored_previously_failed;
+       if num_ignored_total > 0 {
+               log_trace!(logger, "Ignored {} candidate hops due to insufficient value contribution, {} due to path length limit, {} due to CLTV delta limit, {} due to previous payment failure. Total: {} ignored candidates.", num_ignored_value_contribution, num_ignored_path_length_limit, num_ignored_cltv_delta_limit, num_ignored_previously_failed, num_ignored_total);
+       }
+
        // Step (5).
        if payment_paths.len() == 0 {
                return Err(LightningError{err: "Failed to find a path to the given destination".to_owned(), action: ErrorAction::IgnoreError});
@@ -2168,63 +2429,68 @@ where L::Target: Logger {
        // compare both SCIDs and NodeIds as individual nodes may use random aliases causing collisions
        // across nodes.
        selected_route.sort_unstable_by_key(|path| {
-               let mut key = [0u64; MAX_PATH_LENGTH_ESTIMATE as usize];
+               let mut key = [CandidateHopId::Clear((42, true)) ; MAX_PATH_LENGTH_ESTIMATE as usize];
                debug_assert!(path.hops.len() <= key.len());
-               for (scid, key) in path.hops.iter().map(|h| h.0.candidate.short_channel_id()).zip(key.iter_mut()) {
+               for (scid, key) in path.hops.iter() .map(|h| h.0.candidate.id(true)).zip(key.iter_mut()) {
                        *key = scid;
                }
                key
        });
        for idx in 0..(selected_route.len() - 1) {
                if idx + 1 >= selected_route.len() { break; }
-               if iter_equal(selected_route[idx    ].hops.iter().map(|h| (h.0.candidate.short_channel_id(), h.0.node_id)),
-                             selected_route[idx + 1].hops.iter().map(|h| (h.0.candidate.short_channel_id(), h.0.node_id))) {
+               if iter_equal(selected_route[idx    ].hops.iter().map(|h| (h.0.candidate.id(true), h.0.node_id)),
+                             selected_route[idx + 1].hops.iter().map(|h| (h.0.candidate.id(true), h.0.node_id))) {
                        let new_value = selected_route[idx].get_value_msat() + selected_route[idx + 1].get_value_msat();
                        selected_route[idx].update_value_and_recompute_fees(new_value);
                        selected_route.remove(idx + 1);
                }
        }
 
-       let mut selected_paths = Vec::<Vec<Result<RouteHop, LightningError>>>::new();
+       let mut paths = Vec::new();
        for payment_path in selected_route {
-               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)})?,
+               let mut hops = Vec::with_capacity(payment_path.hops.len());
+               for (hop, node_features) in payment_path.hops.iter()
+                       .filter(|(h, _)| h.candidate.short_channel_id().is_some())
+               {
+                       hops.push(RouteHop {
+                               pubkey: PublicKey::from_slice(hop.node_id.as_slice()).map_err(|_| LightningError{err: format!("Public key {:?} is invalid", &hop.node_id), action: ErrorAction::IgnoreAndLog(Level::Trace)})?,
                                node_features: node_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.candidate.cltv_expiry_delta(),
-                       })
-               }).collect::<Vec<_>>();
+                               short_channel_id: hop.candidate.short_channel_id().unwrap(),
+                               channel_features: hop.candidate.features(),
+                               fee_msat: hop.fee_msat,
+                               cltv_expiry_delta: hop.candidate.cltv_expiry_delta(),
+                       });
+               }
+               let mut final_cltv_delta = final_cltv_expiry_delta;
+               let blinded_tail = payment_path.hops.last().and_then(|(h, _)| {
+                       if let Some(blinded_path) = h.candidate.blinded_path() {
+                               final_cltv_delta = h.candidate.cltv_expiry_delta();
+                               Some(BlindedTail {
+                                       hops: blinded_path.blinded_hops.clone(),
+                                       blinding_point: blinded_path.blinding_point,
+                                       excess_final_cltv_expiry_delta: 0,
+                                       final_value_msat: h.fee_msat,
+                               })
+                       } else { None }
+               });
                // Propagate the cltv_expiry_delta one hop backwards since the delta from the current hop is
                // applicable for the previous hop.
-               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)
+               hops.iter_mut().rev().fold(final_cltv_delta, |prev_cltv_expiry_delta, hop| {
+                       core::mem::replace(&mut hop.cltv_expiry_delta, prev_cltv_expiry_delta)
                });
-               selected_paths.push(path);
+
+               paths.push(Path { hops, blinded_tail });
        }
        // Make sure we would never create a route with more paths than we allow.
-       debug_assert!(selected_paths.len() <= payment_params.max_path_count.into());
+       debug_assert!(paths.len() <= payment_params.max_path_count.into());
 
        if let Some(node_features) = payment_params.payee.node_features() {
-               for path in selected_paths.iter_mut() {
-                       if let Ok(route_hop) = path.last_mut().unwrap() {
-                               route_hop.node_features = node_features.clone();
-                       }
+               for path in paths.iter_mut() {
+                       path.hops.last_mut().unwrap().node_features = node_features.clone();
                }
        }
 
-       let mut paths: Vec<Path> = Vec::new();
-       for results_vec in selected_paths {
-               let mut hops = Vec::with_capacity(results_vec.len());
-               for res in results_vec { hops.push(res?); }
-               paths.push(Path { hops, blinded_tail: None });
-       }
-       let route = Route {
-               paths,
-               payment_params: Some(payment_params.clone()),
-       };
+       let route = Route { paths, payment_params: Some(payment_params.clone()) };
        log_info!(logger, "Got route: {}", log_route!(route));
        Ok(route)
 }
@@ -2410,9 +2676,10 @@ mod tests {
        use crate::routing::test_utils::{add_channel, add_or_update_node, build_graph, build_line_graph, id_to_feature_flags, get_nodes, update_channel};
        use crate::chain::transaction::OutPoint;
        use crate::sign::EntropySource;
-       use crate::ln::features::{ChannelFeatures, InitFeatures, NodeFeatures};
+       use crate::ln::features::{BlindedHopFeatures, Bolt12InvoiceFeatures, ChannelFeatures, InitFeatures, NodeFeatures};
        use crate::ln::msgs::{ErrorAction, LightningError, UnsignedChannelUpdate, MAX_VALUE_MSAT};
        use crate::ln::channelmanager;
+       use crate::offers::invoice::BlindedPayInfo;
        use crate::util::config::UserConfig;
        use crate::util::test_utils as ln_test_utils;
        use crate::util::chacha20::ChaCha20;
@@ -2460,6 +2727,7 @@ mod tests {
                        balance_msat: 0,
                        outbound_capacity_msat,
                        next_outbound_htlc_limit_msat: outbound_capacity_msat,
+                       next_outbound_htlc_minimum_msat: 0,
                        inbound_capacity_msat: 42,
                        unspendable_punishment_reserve: None,
                        confirmations_required: None,
@@ -2470,7 +2738,8 @@ mod tests {
                        inbound_htlc_minimum_msat: None,
                        inbound_htlc_maximum_msat: None,
                        config: None,
-                       feerate_sat_per_1000_weight: None
+                       feerate_sat_per_1000_weight: None,
+                       channel_shutdown_state: Some(channelmanager::ChannelShutdownState::NotShuttingDown),
                }
        }
 
@@ -3628,7 +3897,7 @@ mod tests {
        fn available_amount_while_routing_test() {
                // Tests whether we choose the correct available channel amount while routing.
 
-               let (secp_ctx, network_graph, mut gossip_sync, chain_monitor, logger) = build_graph();
+               let (secp_ctx, network_graph, gossip_sync, chain_monitor, logger) = build_graph();
                let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
                let scorer = ln_test_utils::TestScorer::new();
                let keys_manager = ln_test_utils::TestKeysInterface::new(&[0u8; 32], Network::Testnet);
@@ -4078,14 +4347,66 @@ mod tests {
 
        #[test]
        fn simple_mpp_route_test() {
+               let (secp_ctx, _, _, _, _) = build_graph();
+               let (_, _, _, nodes) = get_nodes(&secp_ctx);
+               let config = UserConfig::default();
+               let clear_payment_params = PaymentParameters::from_node_id(nodes[2], 42)
+                       .with_bolt11_features(channelmanager::provided_invoice_features(&config)).unwrap();
+               do_simple_mpp_route_test(clear_payment_params);
+
+               // MPP to a 1-hop blinded path for nodes[2]
+               let bolt12_features: Bolt12InvoiceFeatures = channelmanager::provided_invoice_features(&config).to_context();
+               let blinded_path = BlindedPath {
+                       introduction_node_id: nodes[2],
+                       blinding_point: ln_test_utils::pubkey(42),
+                       blinded_hops: vec![BlindedHop { blinded_node_id: ln_test_utils::pubkey(42 as u8), encrypted_payload: Vec::new() }],
+               };
+               let blinded_payinfo = BlindedPayInfo { // These fields are ignored for 1-hop blinded paths
+                       fee_base_msat: 0,
+                       fee_proportional_millionths: 0,
+                       htlc_minimum_msat: 0,
+                       htlc_maximum_msat: 0,
+                       cltv_expiry_delta: 0,
+                       features: BlindedHopFeatures::empty(),
+               };
+               let one_hop_blinded_payment_params = PaymentParameters::blinded(vec![(blinded_payinfo.clone(), blinded_path.clone())])
+                       .with_bolt12_features(bolt12_features.clone()).unwrap();
+               do_simple_mpp_route_test(one_hop_blinded_payment_params.clone());
+
+               // MPP to 3 2-hop blinded paths
+               let mut blinded_path_node_0 = blinded_path.clone();
+               blinded_path_node_0.introduction_node_id = nodes[0];
+               blinded_path_node_0.blinded_hops.push(blinded_path.blinded_hops[0].clone());
+               let mut node_0_payinfo = blinded_payinfo.clone();
+               node_0_payinfo.htlc_maximum_msat = 50_000;
+
+               let mut blinded_path_node_7 = blinded_path_node_0.clone();
+               blinded_path_node_7.introduction_node_id = nodes[7];
+               let mut node_7_payinfo = blinded_payinfo.clone();
+               node_7_payinfo.htlc_maximum_msat = 60_000;
+
+               let mut blinded_path_node_1 = blinded_path_node_0.clone();
+               blinded_path_node_1.introduction_node_id = nodes[1];
+               let mut node_1_payinfo = blinded_payinfo.clone();
+               node_1_payinfo.htlc_maximum_msat = 180_000;
+
+               let two_hop_blinded_payment_params = PaymentParameters::blinded(
+                       vec![
+                               (node_0_payinfo, blinded_path_node_0),
+                               (node_7_payinfo, blinded_path_node_7),
+                               (node_1_payinfo, blinded_path_node_1)
+                       ])
+                       .with_bolt12_features(bolt12_features).unwrap();
+               do_simple_mpp_route_test(two_hop_blinded_payment_params);
+       }
+
+
+       fn do_simple_mpp_route_test(payment_params: PaymentParameters) {
                let (secp_ctx, network_graph, gossip_sync, _, logger) = build_graph();
                let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
                let scorer = ln_test_utils::TestScorer::new();
                let keys_manager = ln_test_utils::TestKeysInterface::new(&[0u8; 32], Network::Testnet);
                let random_seed_bytes = keys_manager.get_secure_random_bytes();
-               let config = UserConfig::default();
-               let payment_params = PaymentParameters::from_node_id(nodes[2], 42)
-                       .with_bolt11_features(channelmanager::provided_invoice_features(&config)).unwrap();
 
                // We need a route consisting of 3 paths:
                // From our node to node2 via node0, node7, node1 (three paths one hop each).
@@ -4214,8 +4535,12 @@ mod tests {
                        assert_eq!(route.paths.len(), 3);
                        let mut total_amount_paid_msat = 0;
                        for path in &route.paths {
-                               assert_eq!(path.hops.len(), 2);
-                               assert_eq!(path.hops.last().unwrap().pubkey, nodes[2]);
+                               if let Some(bt) = &path.blinded_tail {
+                                       assert_eq!(path.hops.len() + if bt.hops.len() == 1 { 0 } else { 1 }, 2);
+                               } else {
+                                       assert_eq!(path.hops.len(), 2);
+                                       assert_eq!(path.hops.last().unwrap().pubkey, nodes[2]);
+                               }
                                total_amount_paid_msat += path.final_value_msat();
                        }
                        assert_eq!(total_amount_paid_msat, 250_000);
@@ -4228,8 +4553,22 @@ mod tests {
                        assert_eq!(route.paths.len(), 3);
                        let mut total_amount_paid_msat = 0;
                        for path in &route.paths {
-                               assert_eq!(path.hops.len(), 2);
-                               assert_eq!(path.hops.last().unwrap().pubkey, nodes[2]);
+                               if payment_params.payee.blinded_route_hints().len() != 0 {
+                                       assert!(path.blinded_tail.is_some()) } else { assert!(path.blinded_tail.is_none()) }
+                               if let Some(bt) = &path.blinded_tail {
+                                       assert_eq!(path.hops.len() + if bt.hops.len() == 1 { 0 } else { 1 }, 2);
+                                       if bt.hops.len() > 1 {
+                                               assert_eq!(path.hops.last().unwrap().pubkey,
+                                                       payment_params.payee.blinded_route_hints().iter()
+                                                               .find(|(p, _)| p.htlc_maximum_msat == path.final_value_msat())
+                                                               .map(|(_, p)| p.introduction_node_id).unwrap());
+                                       } else {
+                                               assert_eq!(path.hops.last().unwrap().pubkey, nodes[2]);
+                                       }
+                               } else {
+                                       assert_eq!(path.hops.len(), 2);
+                                       assert_eq!(path.hops.last().unwrap().pubkey, nodes[2]);
+                               }
                                total_amount_paid_msat += path.final_value_msat();
                        }
                        assert_eq!(total_amount_paid_msat, 290_000);
@@ -5808,7 +6147,7 @@ mod tests {
 
                let params = ProbabilisticScoringFeeParameters::default();
                let mut scorer = ProbabilisticScorer::new(ProbabilisticScoringDecayParameters::default(), &graph, &logger);
-               let features = super::InvoiceFeatures::empty();
+               let features = super::Bolt11InvoiceFeatures::empty();
 
                super::bench_utils::generate_test_routes(&graph, &mut scorer, &params, features, random_init_seed(), 0, 2);
        }
@@ -5892,6 +6231,157 @@ mod tests {
                assert!(route.is_ok());
        }
 
+       #[test]
+       fn abide_by_route_hint_max_htlc() {
+               // Check that we abide by any htlc_maximum_msat provided in the route hints of the payment
+               // params in the final route.
+               let (secp_ctx, network_graph, _, _, logger) = build_graph();
+               let netgraph = network_graph.read_only();
+               let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
+               let scorer = ln_test_utils::TestScorer::new();
+               let keys_manager = ln_test_utils::TestKeysInterface::new(&[0u8; 32], Network::Testnet);
+               let random_seed_bytes = keys_manager.get_secure_random_bytes();
+               let config = UserConfig::default();
+
+               let max_htlc_msat = 50_000;
+               let route_hint_1 = RouteHint(vec![RouteHintHop {
+                       src_node_id: nodes[2],
+                       short_channel_id: 42,
+                       fees: RoutingFees {
+                               base_msat: 100,
+                               proportional_millionths: 0,
+                       },
+                       cltv_expiry_delta: 10,
+                       htlc_minimum_msat: None,
+                       htlc_maximum_msat: Some(max_htlc_msat),
+               }]);
+               let dest_node_id = ln_test_utils::pubkey(42);
+               let payment_params = PaymentParameters::from_node_id(dest_node_id, 42)
+                       .with_route_hints(vec![route_hint_1.clone()]).unwrap()
+                       .with_bolt11_features(channelmanager::provided_invoice_features(&config)).unwrap();
+
+               // Make sure we'll error if our route hints don't have enough liquidity according to their
+               // htlc_maximum_msat.
+               if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id,
+                       &payment_params, &netgraph, None, max_htlc_msat + 1, Arc::clone(&logger), &scorer, &(),
+                       &random_seed_bytes)
+               {
+                       assert_eq!(err, "Failed to find a sufficient route to the given destination");
+               } else { panic!(); }
+
+               // Make sure we'll split an MPP payment across route hints if their htlc_maximum_msat warrants.
+               let mut route_hint_2 = route_hint_1.clone();
+               route_hint_2.0[0].short_channel_id = 43;
+               let payment_params = PaymentParameters::from_node_id(dest_node_id, 42)
+                       .with_route_hints(vec![route_hint_1, route_hint_2]).unwrap()
+                       .with_bolt11_features(channelmanager::provided_invoice_features(&config)).unwrap();
+               let route = get_route(&our_id, &payment_params, &netgraph, None, max_htlc_msat + 1,
+                       Arc::clone(&logger), &scorer, &(), &random_seed_bytes).unwrap();
+               assert_eq!(route.paths.len(), 2);
+               assert!(route.paths[0].hops.last().unwrap().fee_msat <= max_htlc_msat);
+               assert!(route.paths[1].hops.last().unwrap().fee_msat <= max_htlc_msat);
+       }
+
+       #[test]
+       fn direct_channel_to_hints_with_max_htlc() {
+               // Check that if we have a first hop channel peer that's connected to multiple provided route
+               // hints, that we properly split the payment between the route hints if needed.
+               let logger = Arc::new(ln_test_utils::TestLogger::new());
+               let network_graph = Arc::new(NetworkGraph::new(Network::Testnet, Arc::clone(&logger)));
+               let scorer = ln_test_utils::TestScorer::new();
+               let keys_manager = ln_test_utils::TestKeysInterface::new(&[0u8; 32], Network::Testnet);
+               let random_seed_bytes = keys_manager.get_secure_random_bytes();
+               let config = UserConfig::default();
+
+               let our_node_id = ln_test_utils::pubkey(42);
+               let intermed_node_id = ln_test_utils::pubkey(43);
+               let first_hop = vec![get_channel_details(Some(42), intermed_node_id, InitFeatures::from_le_bytes(vec![0b11]), 10_000_000)];
+
+               let amt_msat = 900_000;
+               let max_htlc_msat = 500_000;
+               let route_hint_1 = RouteHint(vec![RouteHintHop {
+                       src_node_id: intermed_node_id,
+                       short_channel_id: 44,
+                       fees: RoutingFees {
+                               base_msat: 100,
+                               proportional_millionths: 0,
+                       },
+                       cltv_expiry_delta: 10,
+                       htlc_minimum_msat: None,
+                       htlc_maximum_msat: Some(max_htlc_msat),
+               }, RouteHintHop {
+                       src_node_id: intermed_node_id,
+                       short_channel_id: 45,
+                       fees: RoutingFees {
+                               base_msat: 100,
+                               proportional_millionths: 0,
+                       },
+                       cltv_expiry_delta: 10,
+                       htlc_minimum_msat: None,
+                       // Check that later route hint max htlcs don't override earlier ones
+                       htlc_maximum_msat: Some(max_htlc_msat - 50),
+               }]);
+               let mut route_hint_2 = route_hint_1.clone();
+               route_hint_2.0[0].short_channel_id = 46;
+               route_hint_2.0[1].short_channel_id = 47;
+               let dest_node_id = ln_test_utils::pubkey(44);
+               let payment_params = PaymentParameters::from_node_id(dest_node_id, 42)
+                       .with_route_hints(vec![route_hint_1, route_hint_2]).unwrap()
+                       .with_bolt11_features(channelmanager::provided_invoice_features(&config)).unwrap();
+
+               let route = get_route(&our_node_id, &payment_params, &network_graph.read_only(),
+                       Some(&first_hop.iter().collect::<Vec<_>>()), amt_msat, Arc::clone(&logger), &scorer, &(),
+                       &random_seed_bytes).unwrap();
+               assert_eq!(route.paths.len(), 2);
+               assert!(route.paths[0].hops.last().unwrap().fee_msat <= max_htlc_msat);
+               assert!(route.paths[1].hops.last().unwrap().fee_msat <= max_htlc_msat);
+               assert_eq!(route.get_total_amount(), amt_msat);
+
+               // Re-run but with two first hop channels connected to the same route hint peers that must be
+               // split between.
+               let first_hops = vec![
+                       get_channel_details(Some(42), intermed_node_id, InitFeatures::from_le_bytes(vec![0b11]), amt_msat - 10),
+                       get_channel_details(Some(43), intermed_node_id, InitFeatures::from_le_bytes(vec![0b11]), amt_msat - 10),
+               ];
+               let route = get_route(&our_node_id, &payment_params, &network_graph.read_only(),
+                       Some(&first_hops.iter().collect::<Vec<_>>()), amt_msat, Arc::clone(&logger), &scorer, &(),
+                       &random_seed_bytes).unwrap();
+               assert_eq!(route.paths.len(), 2);
+               assert!(route.paths[0].hops.last().unwrap().fee_msat <= max_htlc_msat);
+               assert!(route.paths[1].hops.last().unwrap().fee_msat <= max_htlc_msat);
+               assert_eq!(route.get_total_amount(), amt_msat);
+
+               // Make sure this works for blinded route hints.
+               let blinded_path = BlindedPath {
+                       introduction_node_id: intermed_node_id,
+                       blinding_point: ln_test_utils::pubkey(42),
+                       blinded_hops: vec![
+                               BlindedHop { blinded_node_id: ln_test_utils::pubkey(42), encrypted_payload: vec![] },
+                               BlindedHop { blinded_node_id: ln_test_utils::pubkey(43), encrypted_payload: vec![] },
+                       ],
+               };
+               let blinded_payinfo = BlindedPayInfo {
+                       fee_base_msat: 100,
+                       fee_proportional_millionths: 0,
+                       htlc_minimum_msat: 1,
+                       htlc_maximum_msat: max_htlc_msat,
+                       cltv_expiry_delta: 10,
+                       features: BlindedHopFeatures::empty(),
+               };
+               let bolt12_features: Bolt12InvoiceFeatures = channelmanager::provided_invoice_features(&config).to_context();
+               let payment_params = PaymentParameters::blinded(vec![
+                       (blinded_payinfo.clone(), blinded_path.clone()),
+                       (blinded_payinfo.clone(), blinded_path.clone())])
+                       .with_bolt12_features(bolt12_features).unwrap();
+               let route = get_route(&our_node_id, &payment_params, &network_graph.read_only(),
+                       Some(&first_hops.iter().collect::<Vec<_>>()), amt_msat, Arc::clone(&logger), &scorer, &(),
+                       &random_seed_bytes).unwrap();
+               assert_eq!(route.paths.len(), 2);
+               assert!(route.paths[0].hops.last().unwrap().fee_msat <= max_htlc_msat);
+               assert!(route.paths[1].hops.last().unwrap().fee_msat <= max_htlc_msat);
+               assert_eq!(route.get_total_amount(), amt_msat);
+       }
+
        #[test]
        fn blinded_route_ser() {
                let blinded_path_1 = BlindedPath {
@@ -6036,6 +6526,190 @@ mod tests {
                assert_eq!(route.paths[0].blinded_tail.as_ref().unwrap().excess_final_cltv_expiry_delta, 40);
                assert_eq!(route.paths[0].hops.last().unwrap().cltv_expiry_delta, 40);
        }
+
+       #[test]
+       fn simple_blinded_route_hints() {
+               do_simple_blinded_route_hints(1);
+               do_simple_blinded_route_hints(2);
+               do_simple_blinded_route_hints(3);
+       }
+
+       fn do_simple_blinded_route_hints(num_blinded_hops: usize) {
+               // Check that we can generate a route to a blinded path with the expected hops.
+               let (secp_ctx, network, _, _, logger) = build_graph();
+               let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
+               let network_graph = network.read_only();
+
+               let scorer = ln_test_utils::TestScorer::new();
+               let keys_manager = ln_test_utils::TestKeysInterface::new(&[0u8; 32], Network::Testnet);
+               let random_seed_bytes = keys_manager.get_secure_random_bytes();
+
+               let mut blinded_path = BlindedPath {
+                       introduction_node_id: nodes[2],
+                       blinding_point: ln_test_utils::pubkey(42),
+                       blinded_hops: Vec::with_capacity(num_blinded_hops),
+               };
+               for i in 0..num_blinded_hops {
+                       blinded_path.blinded_hops.push(
+                               BlindedHop { blinded_node_id: ln_test_utils::pubkey(42 + i as u8), encrypted_payload: Vec::new() },
+                       );
+               }
+               let blinded_payinfo = BlindedPayInfo {
+                       fee_base_msat: 100,
+                       fee_proportional_millionths: 500,
+                       htlc_minimum_msat: 1000,
+                       htlc_maximum_msat: 100_000_000,
+                       cltv_expiry_delta: 15,
+                       features: BlindedHopFeatures::empty(),
+               };
+
+               let final_amt_msat = 1001;
+               let payment_params = PaymentParameters::blinded(vec![(blinded_payinfo.clone(), blinded_path.clone())]);
+               let route = get_route(&our_id, &payment_params, &network_graph, None, final_amt_msat , Arc::clone(&logger),
+                       &scorer, &(), &random_seed_bytes).unwrap();
+               assert_eq!(route.paths.len(), 1);
+               assert_eq!(route.paths[0].hops.len(), 2);
+
+               let tail = route.paths[0].blinded_tail.as_ref().unwrap();
+               assert_eq!(tail.hops, blinded_path.blinded_hops);
+               assert_eq!(tail.excess_final_cltv_expiry_delta, 0);
+               assert_eq!(tail.final_value_msat, 1001);
+
+               let final_hop = route.paths[0].hops.last().unwrap();
+               assert_eq!(final_hop.pubkey, blinded_path.introduction_node_id);
+               if tail.hops.len() > 1 {
+                       assert_eq!(final_hop.fee_msat,
+                               blinded_payinfo.fee_base_msat as u64 + blinded_payinfo.fee_proportional_millionths as u64 * tail.final_value_msat / 1000000);
+                       assert_eq!(final_hop.cltv_expiry_delta, blinded_payinfo.cltv_expiry_delta as u32);
+               } else {
+                       assert_eq!(final_hop.fee_msat, 0);
+                       assert_eq!(final_hop.cltv_expiry_delta, 0);
+               }
+       }
+
+       #[test]
+       fn blinded_path_routing_errors() {
+               // Check that we can generate a route to a blinded path with the expected hops.
+               let (secp_ctx, network, _, _, logger) = build_graph();
+               let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
+               let network_graph = network.read_only();
+
+               let scorer = ln_test_utils::TestScorer::new();
+               let keys_manager = ln_test_utils::TestKeysInterface::new(&[0u8; 32], Network::Testnet);
+               let random_seed_bytes = keys_manager.get_secure_random_bytes();
+
+               let mut invalid_blinded_path = BlindedPath {
+                       introduction_node_id: nodes[2],
+                       blinding_point: ln_test_utils::pubkey(42),
+                       blinded_hops: vec![
+                               BlindedHop { blinded_node_id: ln_test_utils::pubkey(43), encrypted_payload: vec![0; 43] },
+                       ],
+               };
+               let blinded_payinfo = BlindedPayInfo {
+                       fee_base_msat: 100,
+                       fee_proportional_millionths: 500,
+                       htlc_minimum_msat: 1000,
+                       htlc_maximum_msat: 100_000_000,
+                       cltv_expiry_delta: 15,
+                       features: BlindedHopFeatures::empty(),
+               };
+
+               let mut invalid_blinded_path_2 = invalid_blinded_path.clone();
+               invalid_blinded_path_2.introduction_node_id = ln_test_utils::pubkey(45);
+               let payment_params = PaymentParameters::blinded(vec![
+                       (blinded_payinfo.clone(), invalid_blinded_path.clone()),
+                       (blinded_payinfo.clone(), invalid_blinded_path_2)]);
+               match get_route(&our_id, &payment_params, &network_graph, None, 1001, Arc::clone(&logger),
+                       &scorer, &(), &random_seed_bytes)
+               {
+                       Err(LightningError { err, .. }) => {
+                               assert_eq!(err, "1-hop blinded paths must all have matching introduction node ids");
+                       },
+                       _ => panic!("Expected error")
+               }
+
+               invalid_blinded_path.introduction_node_id = our_id;
+               let payment_params = PaymentParameters::blinded(vec![(blinded_payinfo.clone(), invalid_blinded_path.clone())]);
+               match get_route(&our_id, &payment_params, &network_graph, None, 1001, Arc::clone(&logger),
+                       &scorer, &(), &random_seed_bytes)
+               {
+                       Err(LightningError { err, .. }) => {
+                               assert_eq!(err, "Cannot generate a route to blinded paths if we are the introduction node to all of them");
+                       },
+                       _ => panic!("Expected error")
+               }
+
+               invalid_blinded_path.introduction_node_id = ln_test_utils::pubkey(46);
+               invalid_blinded_path.blinded_hops.clear();
+               let payment_params = PaymentParameters::blinded(vec![(blinded_payinfo, invalid_blinded_path)]);
+               match get_route(&our_id, &payment_params, &network_graph, None, 1001, Arc::clone(&logger),
+                       &scorer, &(), &random_seed_bytes)
+               {
+                       Err(LightningError { err, .. }) => {
+                               assert_eq!(err, "0-hop blinded path provided");
+                       },
+                       _ => panic!("Expected error")
+               }
+       }
+
+       #[test]
+       fn matching_intro_node_paths_provided() {
+               // Check that if multiple blinded paths with the same intro node are provided in payment
+               // parameters, we'll return the correct paths in the resulting MPP route.
+               let (secp_ctx, network, _, _, logger) = build_graph();
+               let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
+               let network_graph = network.read_only();
+
+               let scorer = ln_test_utils::TestScorer::new();
+               let keys_manager = ln_test_utils::TestKeysInterface::new(&[0u8; 32], Network::Testnet);
+               let random_seed_bytes = keys_manager.get_secure_random_bytes();
+               let config = UserConfig::default();
+
+               let bolt12_features: Bolt12InvoiceFeatures = channelmanager::provided_invoice_features(&config).to_context();
+               let blinded_path_1 = BlindedPath {
+                       introduction_node_id: nodes[2],
+                       blinding_point: ln_test_utils::pubkey(42),
+                       blinded_hops: vec![
+                               BlindedHop { blinded_node_id: ln_test_utils::pubkey(42 as u8), encrypted_payload: Vec::new() },
+                               BlindedHop { blinded_node_id: ln_test_utils::pubkey(42 as u8), encrypted_payload: Vec::new() }
+                       ],
+               };
+               let blinded_payinfo_1 = BlindedPayInfo {
+                       fee_base_msat: 0,
+                       fee_proportional_millionths: 0,
+                       htlc_minimum_msat: 0,
+                       htlc_maximum_msat: 30_000,
+                       cltv_expiry_delta: 0,
+                       features: BlindedHopFeatures::empty(),
+               };
+
+               let mut blinded_path_2 = blinded_path_1.clone();
+               blinded_path_2.blinding_point = ln_test_utils::pubkey(43);
+               let mut blinded_payinfo_2 = blinded_payinfo_1.clone();
+               blinded_payinfo_2.htlc_maximum_msat = 70_000;
+
+               let blinded_hints = vec![
+                       (blinded_payinfo_1.clone(), blinded_path_1.clone()),
+                       (blinded_payinfo_2.clone(), blinded_path_2.clone()),
+               ];
+               let payment_params = PaymentParameters::blinded(blinded_hints.clone())
+                       .with_bolt12_features(bolt12_features.clone()).unwrap();
+
+               let route = get_route(&our_id, &payment_params, &network_graph, None,
+                       100_000, Arc::clone(&logger), &scorer, &(), &random_seed_bytes).unwrap();
+               assert_eq!(route.paths.len(), 2);
+               let mut total_amount_paid_msat = 0;
+               for path in route.paths.into_iter() {
+                       assert_eq!(path.hops.last().unwrap().pubkey, nodes[2]);
+                       if let Some(bt) = &path.blinded_tail {
+                               assert_eq!(bt.blinding_point,
+                                       blinded_hints.iter().find(|(p, _)| p.htlc_maximum_msat == path.final_value_msat())
+                                               .map(|(_, bp)| bp.blinding_point).unwrap());
+                       } else { panic!(); }
+                       total_amount_paid_msat += path.final_value_msat();
+               }
+               assert_eq!(total_amount_paid_msat, 100_000);
+       }
 }
 
 #[cfg(all(any(test, ldk_bench), not(feature = "no-std")))]
@@ -6049,7 +6723,7 @@ pub(crate) mod bench_utils {
        use crate::chain::transaction::OutPoint;
        use crate::sign::{EntropySource, KeysManager};
        use crate::ln::channelmanager::{self, ChannelCounterparty, ChannelDetails};
-       use crate::ln::features::InvoiceFeatures;
+       use crate::ln::features::Bolt11InvoiceFeatures;
        use crate::routing::gossip::NetworkGraph;
        use crate::util::config::UserConfig;
        use crate::util::ser::ReadableArgs;
@@ -6121,6 +6795,7 @@ pub(crate) mod bench_utils {
                        user_channel_id: 0,
                        balance_msat: 10_000_000_000,
                        outbound_capacity_msat: 10_000_000_000,
+                       next_outbound_htlc_minimum_msat: 0,
                        next_outbound_htlc_limit_msat: 10_000_000_000,
                        inbound_capacity_msat: 0,
                        unspendable_punishment_reserve: None,
@@ -6135,11 +6810,12 @@ pub(crate) mod bench_utils {
                        inbound_htlc_maximum_msat: None,
                        config: None,
                        feerate_sat_per_1000_weight: None,
+                       channel_shutdown_state: Some(channelmanager::ChannelShutdownState::NotShuttingDown),
                }
        }
 
        pub(crate) fn generate_test_routes<S: Score>(graph: &NetworkGraph<&TestLogger>, scorer: &mut S,
-               score_params: &S::ScoreParams, features: InvoiceFeatures, mut seed: u64,
+               score_params: &S::ScoreParams, features: Bolt11InvoiceFeatures, mut seed: u64,
                starting_amount: u64, route_count: usize,
        ) -> Vec<(ChannelDetails, PaymentParameters, u64)> {
                let payer = payer_pubkey();
@@ -6220,7 +6896,7 @@ pub mod benches {
        use super::*;
        use crate::sign::{EntropySource, KeysManager};
        use crate::ln::channelmanager;
-       use crate::ln::features::InvoiceFeatures;
+       use crate::ln::features::Bolt11InvoiceFeatures;
        use crate::routing::gossip::NetworkGraph;
        use crate::routing::scoring::{FixedPenaltyScorer, ProbabilisticScorer, ProbabilisticScoringFeeParameters, ProbabilisticScoringDecayParameters};
        use crate::util::config::UserConfig;
@@ -6238,7 +6914,7 @@ pub mod benches {
                let logger = TestLogger::new();
                let network_graph = bench_utils::read_network_graph(&logger).unwrap();
                let scorer = FixedPenaltyScorer::with_penalty(0);
-               generate_routes(bench, &network_graph, scorer, &(), InvoiceFeatures::empty(), 0,
+               generate_routes(bench, &network_graph, scorer, &(), Bolt11InvoiceFeatures::empty(), 0,
                        "generate_routes_with_zero_penalty_scorer");
        }
 
@@ -6256,7 +6932,7 @@ pub mod benches {
                let network_graph = bench_utils::read_network_graph(&logger).unwrap();
                let params = ProbabilisticScoringFeeParameters::default();
                let scorer = ProbabilisticScorer::new(ProbabilisticScoringDecayParameters::default(), &network_graph, &logger);
-               generate_routes(bench, &network_graph, scorer, &params, InvoiceFeatures::empty(), 0,
+               generate_routes(bench, &network_graph, scorer, &params, Bolt11InvoiceFeatures::empty(), 0,
                        "generate_routes_with_probabilistic_scorer");
        }
 
@@ -6282,7 +6958,7 @@ pub mod benches {
 
        fn generate_routes<S: Score>(
                bench: &mut Criterion, graph: &NetworkGraph<&TestLogger>, mut scorer: S,
-               score_params: &S::ScoreParams, features: InvoiceFeatures, starting_amount: u64,
+               score_params: &S::ScoreParams, features: Bolt11InvoiceFeatures, starting_amount: u64,
                bench_name: &'static str,
        ) {
                let payer = bench_utils::payer_pubkey();