_ Git - rust-lightning/blob - lightning/src/routing/router.rs

   1 // This file is Copyright its original authors, visible in version control
   2 // history.
   3 //
   4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
   5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
   7 // You may not use this file except in accordance with one or both of these
   8 // licenses.
   9
  10 //! The top-level routing/network map tracking logic lives here.
  11 //!
  12 //! You probably want to create a NetGraphMsgHandler and use that as your RoutingMessageHandler and then
  13 //! interrogate it to get routes for your own payments.
  14
  15 use bitcoin::secp256k1::key::PublicKey;
  16
  17 use ln::channelmanager::ChannelDetails;
  18 use ln::features::{ChannelFeatures, InvoiceFeatures, NodeFeatures};
  19 use ln::msgs::{DecodeError, ErrorAction, LightningError, MAX_VALUE_MSAT};
  20 use routing::scoring::Score;
  21 use routing::network_graph::{ChannelInfo, DirectedChannelInfo, DirectionalChannelInfo, EffectiveCapacity, NetworkGraph, NodeId, RoutingFees};
  22 use util::ser::{Writeable, Readable};
  23 use util::logger::{Level, Logger};
  24
  25 use io;
  26 use prelude::*;
  27 use alloc::collections::BinaryHeap;
  28 use core::cmp;
  29 use core::ops::Deref;
  30
  31 /// A hop in a route
  32 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
  33 pub struct RouteHop {
  34         /// The node_id of the node at this hop.
  35         pub pubkey: PublicKey,
  36         /// The node_announcement features of the node at this hop. For the last hop, these may be
  37         /// amended to match the features present in the invoice this node generated.
  38         pub node_features: NodeFeatures,
  39         /// The channel that should be used from the previous hop to reach this node.
  40         pub short_channel_id: u64,
  41         /// The channel_announcement features of the channel that should be used from the previous hop
  42         /// to reach this node.
  43         pub channel_features: ChannelFeatures,
  44         /// The fee taken on this hop (for paying for the use of the *next* channel in the path).
  45         /// For the last hop, this should be the full value of the payment (might be more than
  46         /// requested if we had to match htlc_minimum_msat).
  47         pub fee_msat: u64,
  48         /// The CLTV delta added for this hop. For the last hop, this should be the full CLTV value
  49         /// expected at the destination, in excess of the current block height.
  50         pub cltv_expiry_delta: u32,
  51 }
  52
  53 impl_writeable_tlv_based!(RouteHop, {
  54         (0, pubkey, required),
  55         (2, node_features, required),
  56         (4, short_channel_id, required),
  57         (6, channel_features, required),
  58         (8, fee_msat, required),
  59         (10, cltv_expiry_delta, required),
  60 });
  61
  62 /// A route directs a payment from the sender (us) to the recipient. If the recipient supports MPP,
  63 /// it can take multiple paths. Each path is composed of one or more hops through the network.
  64 #[derive(Clone, Hash, PartialEq, Eq)]
  65 pub struct Route {
  66         /// The list of routes taken for a single (potentially-)multi-part payment. The pubkey of the
  67         /// last RouteHop in each path must be the same.
  68         /// Each entry represents a list of hops, NOT INCLUDING our own, where the last hop is the
  69         /// destination. Thus, this must always be at least length one. While the maximum length of any
  70         /// given path is variable, keeping the length of any path to less than 20 should currently
  71         /// ensure it is viable.
  72         pub paths: Vec<Vec<RouteHop>>,
  73         /// The `payee` parameter passed to [`find_route`].
  74         /// This is used by `ChannelManager` to track information which may be required for retries,
  75         /// provided back to you via [`Event::PaymentPathFailed`].
  76         ///
  77         /// [`Event::PaymentPathFailed`]: crate::util::events::Event::PaymentPathFailed
  78         pub payee: Option<Payee>,
  79 }
  80
  81 pub(crate) trait RoutePath {
  82         /// Gets the fees for a given path, excluding any excess paid to the recipient.
  83         fn get_path_fees(&self) -> u64;
  84 }
  85 impl RoutePath for Vec<RouteHop> {
  86         fn get_path_fees(&self) -> u64 {
  87                 // Do not count last hop of each path since that's the full value of the payment
  88                 self.split_last().map(|(_, path_prefix)| path_prefix).unwrap_or(&[])
  89                         .iter().map(|hop| &hop.fee_msat)
  90                         .sum()
  91         }
  92 }
  93
  94 impl Route {
  95         /// Returns the total amount of fees paid on this [`Route`].
  96         ///
  97         /// This doesn't include any extra payment made to the recipient, which can happen in excess of
  98         /// the amount passed to [`find_route`]'s `params.final_value_msat`.
  99         pub fn get_total_fees(&self) -> u64 {
 100                 self.paths.iter().map(|path| path.get_path_fees()).sum()
 101         }
 102
 103         /// Returns the total amount paid on this [`Route`], excluding the fees.
 104         pub fn get_total_amount(&self) -> u64 {
 105                 return self.paths.iter()
 106                         .map(|path| path.split_last().map(|(hop, _)| hop.fee_msat).unwrap_or(0))
 107                         .sum();
 108         }
 109 }
 110
 111 const SERIALIZATION_VERSION: u8 = 1;
 112 const MIN_SERIALIZATION_VERSION: u8 = 1;
 113
 114 impl Writeable for Route {
 115         fn write<W: ::util::ser::Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 116                 write_ver_prefix!(writer, SERIALIZATION_VERSION, MIN_SERIALIZATION_VERSION);
 117                 (self.paths.len() as u64).write(writer)?;
 118                 for hops in self.paths.iter() {
 119                         (hops.len() as u8).write(writer)?;
 120                         for hop in hops.iter() {
 121                                 hop.write(writer)?;
 122                         }
 123                 }
 124                 write_tlv_fields!(writer, {
 125                         (1, self.payee, option),
 126                 });
 127                 Ok(())
 128         }
 129 }
 130
 131 impl Readable for Route {
 132         fn read<R: io::Read>(reader: &mut R) -> Result<Route, DecodeError> {
 133                 let _ver = read_ver_prefix!(reader, SERIALIZATION_VERSION);
 134                 let path_count: u64 = Readable::read(reader)?;
 135                 let mut paths = Vec::with_capacity(cmp::min(path_count, 128) as usize);
 136                 for _ in 0..path_count {
 137                         let hop_count: u8 = Readable::read(reader)?;
 138                         let mut hops = Vec::with_capacity(hop_count as usize);
 139                         for _ in 0..hop_count {
 140                                 hops.push(Readable::read(reader)?);
 141                         }
 142                         paths.push(hops);
 143                 }
 144                 let mut payee = None;
 145                 read_tlv_fields!(reader, {
 146                         (1, payee, option),
 147                 });
 148                 Ok(Route { paths, payee })
 149         }
 150 }
 151
 152 /// Parameters needed to find a [`Route`] for paying a [`Payee`].
 153 ///
 154 /// Passed to [`find_route`] and also provided in [`Event::PaymentPathFailed`] for retrying a failed
 155 /// payment path.
 156 ///
 157 /// [`Event::PaymentPathFailed`]: crate::util::events::Event::PaymentPathFailed
 158 #[derive(Clone, Debug)]
 159 pub struct RouteParameters {
 160         /// The recipient of the failed payment path.
 161         pub payee: Payee,
 162
 163         /// The amount in msats sent on the failed payment path.
 164         pub final_value_msat: u64,
 165
 166         /// The CLTV on the final hop of the failed payment path.
 167         pub final_cltv_expiry_delta: u32,
 168 }
 169
 170 impl_writeable_tlv_based!(RouteParameters, {
 171         (0, payee, required),
 172         (2, final_value_msat, required),
 173         (4, final_cltv_expiry_delta, required),
 174 });
 175
 176 /// The recipient of a payment.
 177 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
 178 pub struct Payee {
 179         /// The node id of the payee.
 180         pub pubkey: PublicKey,
 181
 182         /// Features supported by the payee.
 183         ///
 184         /// May be set from the payee's invoice or via [`for_keysend`]. May be `None` if the invoice
 185         /// does not contain any features.
 186         ///
 187         /// [`for_keysend`]: Self::for_keysend
 188         pub features: Option<InvoiceFeatures>,
 189
 190         /// Hints for routing to the payee, containing channels connecting the payee to public nodes.
 191         pub route_hints: Vec<RouteHint>,
 192
 193         /// Expiration of a payment to the payee, in seconds relative to the UNIX epoch.
 194         pub expiry_time: Option<u64>,
 195 }
 196
 197 impl_writeable_tlv_based!(Payee, {
 198         (0, pubkey, required),
 199         (2, features, option),
 200         (4, route_hints, vec_type),
 201         (6, expiry_time, option),
 202 });
 203
 204 impl Payee {
 205         /// Creates a payee with the node id of the given `pubkey`.
 206         pub fn from_node_id(pubkey: PublicKey) -> Self {
 207                 Self {
 208                         pubkey,
 209                         features: None,
 210                         route_hints: vec![],
 211                         expiry_time: None,
 212                 }
 213         }
 214
 215         /// Creates a payee with the node id of the given `pubkey` to use for keysend payments.
 216         pub fn for_keysend(pubkey: PublicKey) -> Self {
 217                 Self::from_node_id(pubkey).with_features(InvoiceFeatures::for_keysend())
 218         }
 219
 220         /// Includes the payee's features.
 221         ///
 222         /// (C-not exported) since bindings don't support move semantics
 223         pub fn with_features(self, features: InvoiceFeatures) -> Self {
 224                 Self { features: Some(features), ..self }
 225         }
 226
 227         /// Includes hints for routing to the payee.
 228         ///
 229         /// (C-not exported) since bindings don't support move semantics
 230         pub fn with_route_hints(self, route_hints: Vec<RouteHint>) -> Self {
 231                 Self { route_hints, ..self }
 232         }
 233
 234         /// Includes a payment expiration in seconds relative to the UNIX epoch.
 235         ///
 236         /// (C-not exported) since bindings don't support move semantics
 237         pub fn with_expiry_time(self, expiry_time: u64) -> Self {
 238                 Self { expiry_time: Some(expiry_time), ..self }
 239         }
 240 }
 241
 242 /// A list of hops along a payment path terminating with a channel to the recipient.
 243 #[derive(Clone, Debug, Hash, Eq, PartialEq)]
 244 pub struct RouteHint(pub Vec<RouteHintHop>);
 245
 246
 247 impl Writeable for RouteHint {
 248         fn write<W: ::util::ser::Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 249                 (self.0.len() as u64).write(writer)?;
 250                 for hop in self.0.iter() {
 251                         hop.write(writer)?;
 252                 }
 253                 Ok(())
 254         }
 255 }
 256
 257 impl Readable for RouteHint {
 258         fn read<R: io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
 259                 let hop_count: u64 = Readable::read(reader)?;
 260                 let mut hops = Vec::with_capacity(cmp::min(hop_count, 16) as usize);
 261                 for _ in 0..hop_count {
 262                         hops.push(Readable::read(reader)?);
 263                 }
 264                 Ok(Self(hops))
 265         }
 266 }
 267
 268 /// A channel descriptor for a hop along a payment path.
 269 #[derive(Clone, Debug, Hash, Eq, PartialEq)]
 270 pub struct RouteHintHop {
 271         /// The node_id of the non-target end of the route
 272         pub src_node_id: PublicKey,
 273         /// The short_channel_id of this channel
 274         pub short_channel_id: u64,
 275         /// The fees which must be paid to use this channel
 276         pub fees: RoutingFees,
 277         /// The difference in CLTV values between this node and the next node.
 278         pub cltv_expiry_delta: u16,
 279         /// The minimum value, in msat, which must be relayed to the next hop.
 280         pub htlc_minimum_msat: Option<u64>,
 281         /// The maximum value in msat available for routing with a single HTLC.
 282         pub htlc_maximum_msat: Option<u64>,
 283 }
 284
 285 impl_writeable_tlv_based!(RouteHintHop, {
 286         (0, src_node_id, required),
 287         (1, htlc_minimum_msat, option),
 288         (2, short_channel_id, required),
 289         (3, htlc_maximum_msat, option),
 290         (4, fees, required),
 291         (6, cltv_expiry_delta, required),
 292 });
 293
 294 #[derive(Eq, PartialEq)]
 295 struct RouteGraphNode {
 296         node_id: NodeId,
 297         lowest_fee_to_peer_through_node: u64,
 298         lowest_fee_to_node: u64,
 299         // The maximum value a yet-to-be-constructed payment path might flow through this node.
 300         // This value is upper-bounded by us by:
 301         // - how much is needed for a path being constructed
 302         // - how much value can channels following this node (up to the destination) can contribute,
 303         //   considering their capacity and fees
 304         value_contribution_msat: u64,
 305         /// The effective htlc_minimum_msat at this hop. If a later hop on the path had a higher HTLC
 306         /// minimum, we use it, plus the fees required at each earlier hop to meet it.
 307         path_htlc_minimum_msat: u64,
 308         /// All penalties incurred from this hop on the way to the destination, as calculated using
 309         /// channel scoring.
 310         path_penalty_msat: u64,
 311 }
 312
 313 impl cmp::Ord for RouteGraphNode {
 314         fn cmp(&self, other: &RouteGraphNode) -> cmp::Ordering {
 315                 let other_score = cmp::max(other.lowest_fee_to_peer_through_node, other.path_htlc_minimum_msat)
 316                         .checked_add(other.path_penalty_msat)
 317                         .unwrap_or_else(|| u64::max_value());
 318                 let self_score = cmp::max(self.lowest_fee_to_peer_through_node, self.path_htlc_minimum_msat)
 319                         .checked_add(self.path_penalty_msat)
 320                         .unwrap_or_else(|| u64::max_value());
 321                 other_score.cmp(&self_score).then_with(|| other.node_id.cmp(&self.node_id))
 322         }
 323 }
 324
 325 impl cmp::PartialOrd for RouteGraphNode {
 326         fn partial_cmp(&self, other: &RouteGraphNode) -> Option<cmp::Ordering> {
 327                 Some(self.cmp(other))
 328         }
 329 }
 330
 331 /// A wrapper around the various hop representations.
 332 ///
 333 /// Used to construct a [`PathBuildingHop`] and to estimate [`EffectiveCapacity`].
 334 enum CandidateRouteHop<'a> {
 335         /// A hop from the payer to the next hop to the payee, where the outbound liquidity is known.
 336         FirstHop {
 337                 details: &'a ChannelDetails,
 338         },
 339         /// A hop found in the [`NetworkGraph`], where the channel capacity may or may not be known.
 340         PublicHop {
 341                 short_channel_id: u64,
 342                 channel: &'a ChannelInfo,
 343                 direction: &'a DirectionalChannelInfo,
 344         },
 345         /// A hop to the payee found in the payment invoice, though not necessarily a direct channel.
 346         PrivateHop {
 347                 hint: &'a RouteHintHop,
 348         }
 349 }
 350
 351 impl<'a> CandidateRouteHop<'a> {
 352         fn short_channel_id(&self) -> u64 {
 353                 match self {
 354                         CandidateRouteHop::FirstHop { details } => details.short_channel_id.unwrap(),
 355                         CandidateRouteHop::PublicHop { short_channel_id, .. } => *short_channel_id,
 356                         CandidateRouteHop::PrivateHop { hint } => hint.short_channel_id,
 357                 }
 358         }
 359
 360         fn features(&self) -> ChannelFeatures {
 361                 match self {
 362                         CandidateRouteHop::FirstHop { details } => details.counterparty.features.to_context(),
 363                         CandidateRouteHop::PublicHop { channel, .. } => channel.features.clone(),
 364                         CandidateRouteHop::PrivateHop { .. } => ChannelFeatures::empty(),
 365                 }
 366         }
 367
 368         fn cltv_expiry_delta(&self) -> u32 {
 369                 match self {
 370                         CandidateRouteHop::FirstHop { .. } => 0,
 371                         CandidateRouteHop::PublicHop { direction, .. } => direction.cltv_expiry_delta as u32,
 372                         CandidateRouteHop::PrivateHop { hint } => hint.cltv_expiry_delta as u32,
 373                 }
 374         }
 375
 376         fn htlc_minimum_msat(&self) -> u64 {
 377                 match self {
 378                         CandidateRouteHop::FirstHop { .. } => 0,
 379                         CandidateRouteHop::PublicHop { direction, .. } => direction.htlc_minimum_msat,
 380                         CandidateRouteHop::PrivateHop { hint } => hint.htlc_minimum_msat.unwrap_or(0),
 381                 }
 382         }
 383
 384         fn fees(&self) -> RoutingFees {
 385                 match self {
 386                         CandidateRouteHop::FirstHop { .. } => RoutingFees {
 387                                 base_msat: 0, proportional_millionths: 0,
 388                         },
 389                         CandidateRouteHop::PublicHop { direction, .. } => direction.fees,
 390                         CandidateRouteHop::PrivateHop { hint } => hint.fees,
 391                 }
 392         }
 393
 394         fn effective_capacity(&self) -> EffectiveCapacity {
 395                 match self {
 396                         CandidateRouteHop::FirstHop { details } => EffectiveCapacity::ExactLiquidity {
 397                                 liquidity_msast: details.outbound_capacity_msat,
 398                         },
 399                         CandidateRouteHop::PublicHop { channel, direction, .. } => {
 400                                 DirectedChannelInfo::effective_capacity_from_parts(channel, Some(direction))
 401                         },
 402                         CandidateRouteHop::PrivateHop { .. } => EffectiveCapacity::Infinite,
 403                 }
 404         }
 405 }
 406
 407 /// It's useful to keep track of the hops associated with the fees required to use them,
 408 /// so that we can choose cheaper paths (as per Dijkstra's algorithm).
 409 /// Fee values should be updated only in the context of the whole path, see update_value_and_recompute_fees.
 410 /// These fee values are useful to choose hops as we traverse the graph "payee-to-payer".
 411 #[derive(Clone, Debug)]
 412 struct PathBuildingHop {
 413         // The RouteHintHop fields which will eventually be used if this hop is used in a final Route.
 414         // Note that node_features is calculated separately after our initial graph walk.
 415         node_id: NodeId,
 416         short_channel_id: u64,
 417         channel_features: ChannelFeatures,
 418         fee_msat: u64,
 419         cltv_expiry_delta: u32,
 420
 421         /// Minimal fees required to route to the source node of the current hop via any of its inbound channels.
 422         src_lowest_inbound_fees: RoutingFees,
 423         /// Fees of the channel used in this hop.
 424         channel_fees: RoutingFees,
 425         /// All the fees paid *after* this channel on the way to the destination
 426         next_hops_fee_msat: u64,
 427         /// Fee paid for the use of the current channel (see channel_fees).
 428         /// The value will be actually deducted from the counterparty balance on the previous link.
 429         hop_use_fee_msat: u64,
 430         /// Used to compare channels when choosing the for routing.
 431         /// Includes paying for the use of a hop and the following hops, as well as
 432         /// an estimated cost of reaching this hop.
 433         /// Might get stale when fees are recomputed. Primarily for internal use.
 434         total_fee_msat: u64,
 435         /// This is useful for update_value_and_recompute_fees to make sure
 436         /// we don't fall below the minimum. Should not be updated manually and
 437         /// generally should not be accessed.
 438         htlc_minimum_msat: u64,
 439         /// A mirror of the same field in RouteGraphNode. Note that this is only used during the graph
 440         /// walk and may be invalid thereafter.
 441         path_htlc_minimum_msat: u64,
 442         /// All penalties incurred from this channel on the way to the destination, as calculated using
 443         /// channel scoring.
 444         path_penalty_msat: u64,
 445         /// If we've already processed a node as the best node, we shouldn't process it again. Normally
 446         /// we'd just ignore it if we did as all channels would have a higher new fee, but because we
 447         /// may decrease the amounts in use as we walk the graph, the actual calculated fee may
 448         /// decrease as well. Thus, we have to explicitly track which nodes have been processed and
 449         /// avoid processing them again.
 450         was_processed: bool,
 451         #[cfg(any(test, feature = "fuzztarget"))]
 452         // In tests, we apply further sanity checks on cases where we skip nodes we already processed
 453         // to ensure it is specifically in cases where the fee has gone down because of a decrease in
 454         // value_contribution_msat, which requires tracking it here. See comments below where it is
 455         // used for more info.
 456         value_contribution_msat: u64,
 457 }
 458
 459 // Instantiated with a list of hops with correct data in them collected during path finding,
 460 // an instance of this struct should be further modified only via given methods.
 461 #[derive(Clone)]
 462 struct PaymentPath {
 463         hops: Vec<(PathBuildingHop, NodeFeatures)>,
 464 }
 465
 466 impl PaymentPath {
 467         // TODO: Add a value_msat field to PaymentPath and use it instead of this function.
 468         fn get_value_msat(&self) -> u64 {
 469                 self.hops.last().unwrap().0.fee_msat
 470         }
 471
 472         fn get_total_fee_paid_msat(&self) -> u64 {
 473                 if self.hops.len() < 1 {
 474                         return 0;
 475                 }
 476                 let mut result = 0;
 477                 // Can't use next_hops_fee_msat because it gets outdated.
 478                 for (i, (hop, _)) in self.hops.iter().enumerate() {
 479                         if i != self.hops.len() - 1 {
 480                                 result += hop.fee_msat;
 481                         }
 482                 }
 483                 return result;
 484         }
 485
 486         // If the amount transferred by the path is updated, the fees should be adjusted. Any other way
 487         // to change fees may result in an inconsistency.
 488         //
 489         // Sometimes we call this function right after constructing a path which is inconsistent in
 490         // that it the value being transferred has decreased while we were doing path finding, leading
 491         // to the fees being paid not lining up with the actual limits.
 492         //
 493         // Note that this function is not aware of the available_liquidity limit, and thus does not
 494         // support increasing the value being transferred.
 495         fn update_value_and_recompute_fees(&mut self, value_msat: u64) {
 496                 assert!(value_msat <= self.hops.last().unwrap().0.fee_msat);
 497
 498                 let mut total_fee_paid_msat = 0 as u64;
 499                 for i in (0..self.hops.len()).rev() {
 500                         let last_hop = i == self.hops.len() - 1;
 501
 502                         // For non-last-hop, this value will represent the fees paid on the current hop. It
 503                         // will consist of the fees for the use of the next hop, and extra fees to match
 504                         // htlc_minimum_msat of the current channel. Last hop is handled separately.
 505                         let mut cur_hop_fees_msat = 0;
 506                         if !last_hop {
 507                                 cur_hop_fees_msat = self.hops.get(i + 1).unwrap().0.hop_use_fee_msat;
 508                         }
 509
 510                         let mut cur_hop = &mut self.hops.get_mut(i).unwrap().0;
 511                         cur_hop.next_hops_fee_msat = total_fee_paid_msat;
 512                         // Overpay in fees if we can't save these funds due to htlc_minimum_msat.
 513                         // We try to account for htlc_minimum_msat in scoring (add_entry!), so that nodes don't
 514                         // set it too high just to maliciously take more fees by exploiting this
 515                         // match htlc_minimum_msat logic.
 516                         let mut cur_hop_transferred_amount_msat = total_fee_paid_msat + value_msat;
 517                         if let Some(extra_fees_msat) = cur_hop.htlc_minimum_msat.checked_sub(cur_hop_transferred_amount_msat) {
 518                                 // Note that there is a risk that *previous hops* (those closer to us, as we go
 519                                 // payee->our_node here) would exceed their htlc_maximum_msat or available balance.
 520                                 //
 521                                 // This might make us end up with a broken route, although this should be super-rare
 522                                 // in practice, both because of how healthy channels look like, and how we pick
 523                                 // channels in add_entry.
 524                                 // Also, this can't be exploited more heavily than *announce a free path and fail
 525                                 // all payments*.
 526                                 cur_hop_transferred_amount_msat += extra_fees_msat;
 527                                 total_fee_paid_msat += extra_fees_msat;
 528                                 cur_hop_fees_msat += extra_fees_msat;
 529                         }
 530
 531                         if last_hop {
 532                                 // Final hop is a special case: it usually has just value_msat (by design), but also
 533                                 // it still could overpay for the htlc_minimum_msat.
 534                                 cur_hop.fee_msat = cur_hop_transferred_amount_msat;
 535                         } else {
 536                                 // Propagate updated fees for the use of the channels to one hop back, where they
 537                                 // will be actually paid (fee_msat). The last hop is handled above separately.
 538                                 cur_hop.fee_msat = cur_hop_fees_msat;
 539                         }
 540
 541                         // Fee for the use of the current hop which will be deducted on the previous hop.
 542                         // Irrelevant for the first hop, as it doesn't have the previous hop, and the use of
 543                         // this channel is free for us.
 544                         if i != 0 {
 545                                 if let Some(new_fee) = compute_fees(cur_hop_transferred_amount_msat, cur_hop.channel_fees) {
 546                                         cur_hop.hop_use_fee_msat = new_fee;
 547                                         total_fee_paid_msat += new_fee;
 548                                 } else {
 549                                         // It should not be possible because this function is called only to reduce the
 550                                         // value. In that case, compute_fee was already called with the same fees for
 551                                         // larger amount and there was no overflow.
 552                                         unreachable!();
 553                                 }
 554                         }
 555                 }
 556         }
 557 }
 558
 559 fn compute_fees(amount_msat: u64, channel_fees: RoutingFees) -> Option<u64> {
 560         let proportional_fee_millions =
 561                 amount_msat.checked_mul(channel_fees.proportional_millionths as u64);
 562         if let Some(new_fee) = proportional_fee_millions.and_then(|part| {
 563                         (channel_fees.base_msat as u64).checked_add(part / 1_000_000) }) {
 564
 565                 Some(new_fee)
 566         } else {
 567                 // This function may be (indirectly) called without any verification,
 568                 // with channel_fees provided by a caller. We should handle it gracefully.
 569                 None
 570         }
 571 }
 572
 573 /// Finds a route from us (payer) to the given target node (payee).
 574 ///
 575 /// If the payee provided features in their invoice, they should be provided via `params.payee`.
 576 /// Without this, MPP will only be used if the payee's features are available in the network graph.
 577 ///
 578 /// Private routing paths between a public node and the target may be included in `params.payee`.
 579 ///
 580 /// If some channels aren't announced, it may be useful to fill in `first_hops` with the results
 581 /// from [`ChannelManager::list_usable_channels`]. If it is filled in, the view of our local
 582 /// channels from [`NetworkGraph`] will be ignored, and only those in `first_hops` will be used.
 583 ///
 584 /// The fees on channels from us to the next hop are ignored as they are assumed to all be equal.
 585 /// However, the enabled/disabled bit on such channels as well as the `htlc_minimum_msat` /
 586 /// `htlc_maximum_msat` *are* checked as they may change based on the receiving node.
 587 ///
 588 /// # Note
 589 ///
 590 /// May be used to re-compute a [`Route`] when handling a [`Event::PaymentPathFailed`]. Any
 591 /// adjustments to the [`NetworkGraph`] and channel scores should be made prior to calling this
 592 /// function.
 593 ///
 594 /// # Panics
 595 ///
 596 /// Panics if first_hops contains channels without short_channel_ids;
 597 /// [`ChannelManager::list_usable_channels`] will never include such channels.
 598 ///
 599 /// [`ChannelManager::list_usable_channels`]: crate::ln::channelmanager::ChannelManager::list_usable_channels
 600 /// [`Event::PaymentPathFailed`]: crate::util::events::Event::PaymentPathFailed
 601 pub fn find_route<L: Deref, S: Score>(
 602         our_node_pubkey: &PublicKey, params: &RouteParameters, network: &NetworkGraph,
 603         first_hops: Option<&[&ChannelDetails]>, logger: L, scorer: &S
 604 ) -> Result<Route, LightningError>
 605 where L::Target: Logger {
 606         get_route(
 607                 our_node_pubkey, &params.payee, network, first_hops, params.final_value_msat,
 608                 params.final_cltv_expiry_delta, logger, scorer
 609         )
 610 }
 611
 612 pub(crate) fn get_route<L: Deref, S: Score>(
 613         our_node_pubkey: &PublicKey, payee: &Payee, network: &NetworkGraph,
 614         first_hops: Option<&[&ChannelDetails]>, final_value_msat: u64, final_cltv_expiry_delta: u32,
 615         logger: L, scorer: &S
 616 ) -> Result<Route, LightningError>
 617 where L::Target: Logger {
 618         let payee_node_id = NodeId::from_pubkey(&payee.pubkey);
 619         let our_node_id = NodeId::from_pubkey(&our_node_pubkey);
 620
 621         if payee_node_id == our_node_id {
 622                 return Err(LightningError{err: "Cannot generate a route to ourselves".to_owned(), action: ErrorAction::IgnoreError});
 623         }
 624
 625         if final_value_msat > MAX_VALUE_MSAT {
 626                 return Err(LightningError{err: "Cannot generate a route of more value than all existing satoshis".to_owned(), action: ErrorAction::IgnoreError});
 627         }
 628
 629         if final_value_msat == 0 {
 630                 return Err(LightningError{err: "Cannot send a payment of 0 msat".to_owned(), action: ErrorAction::IgnoreError});
 631         }
 632
 633         for route in payee.route_hints.iter() {
 634                 for hop in &route.0 {
 635                         if hop.src_node_id == payee.pubkey {
 636                                 return Err(LightningError{err: "Route hint cannot have the payee as the source.".to_owned(), action: ErrorAction::IgnoreError});
 637                         }
 638                 }
 639         }
 640
 641         // The general routing idea is the following:
 642         // 1. Fill first/last hops communicated by the caller.
 643         // 2. Attempt to construct a path from payer to payee for transferring
 644         //    any ~sufficient (described later) value.
 645         //    If succeed, remember which channels were used and how much liquidity they have available,
 646         //    so that future paths don't rely on the same liquidity.
 647         // 3. Prooceed to the next step if:
 648         //    - we hit the recommended target value;
 649         //    - OR if we could not construct a new path. Any next attempt will fail too.
 650         //    Otherwise, repeat step 2.
 651         // 4. See if we managed to collect paths which aggregately are able to transfer target value
 652         //    (not recommended value). If yes, proceed. If not, fail routing.
 653         // 5. Randomly combine paths into routes having enough to fulfill the payment. (TODO: knapsack)
 654         // 6. Of all the found paths, select only those with the lowest total fee.
 655         // 7. The last path in every selected route is likely to be more than we need.
 656         //    Reduce its value-to-transfer and recompute fees.
 657         // 8. Choose the best route by the lowest total fee.
 658
 659         // As for the actual search algorithm,
 660         // we do a payee-to-payer pseudo-Dijkstra's sorting by each node's distance from the payee
 661         // plus the minimum per-HTLC fee to get from it to another node (aka "shitty pseudo-A*").
 662         //
 663         // We are not a faithful Dijkstra's implementation because we can change values which impact
 664         // earlier nodes while processing later nodes. Specifically, if we reach a channel with a lower
 665         // liquidity limit (via htlc_maximum_msat, on-chain capacity or assumed liquidity limits) then
 666         // the value we are currently attempting to send over a path, we simply reduce the value being
 667         // sent along the path for any hops after that channel. This may imply that later fees (which
 668         // we've already tabulated) are lower because a smaller value is passing through the channels
 669         // (and the proportional fee is thus lower). There isn't a trivial way to recalculate the
 670         // channels which were selected earlier (and which may still be used for other paths without a
 671         // lower liquidity limit), so we simply accept that some liquidity-limited paths may be
 672         // de-preferenced.
 673         //
 674         // One potentially problematic case for this algorithm would be if there are many
 675         // liquidity-limited paths which are liquidity-limited near the destination (ie early in our
 676         // graph walking), we may never find a path which is not liquidity-limited and has lower
 677         // proportional fee (and only lower absolute fee when considering the ultimate value sent).
 678         // Because we only consider paths with at least 5% of the total value being sent, the damage
 679         // from such a case should be limited, however this could be further reduced in the future by
 680         // calculating fees on the amount we wish to route over a path, ie ignoring the liquidity
 681         // limits for the purposes of fee calculation.
 682         //
 683         // Alternatively, we could store more detailed path information in the heap (targets, below)
 684         // and index the best-path map (dist, below) by node *and* HTLC limits, however that would blow
 685         // up the runtime significantly both algorithmically (as we'd traverse nodes multiple times)
 686         // and practically (as we would need to store dynamically-allocated path information in heap
 687         // objects, increasing malloc traffic and indirect memory access significantly). Further, the
 688         // results of such an algorithm would likely be biased towards lower-value paths.
 689         //
 690         // Further, we could return to a faithful Dijkstra's algorithm by rejecting paths with limits
 691         // outside of our current search value, running a path search more times to gather candidate
 692         // paths at different values. While this may be acceptable, further path searches may increase
 693         // runtime for little gain. Specifically, the current algorithm rather efficiently explores the
 694         // graph for candidate paths, calculating the maximum value which can realistically be sent at
 695         // the same time, remaining generic across different payment values.
 696         //
 697         // TODO: There are a few tweaks we could do, including possibly pre-calculating more stuff
 698         // to use as the A* heuristic beyond just the cost to get one node further than the current
 699         // one.
 700
 701         let network_graph = network.read_only();
 702         let network_channels = network_graph.channels();
 703         let network_nodes = network_graph.nodes();
 704
 705         // Allow MPP only if we have a features set from somewhere that indicates the payee supports
 706         // it. If the payee supports it they're supposed to include it in the invoice, so that should
 707         // work reliably.
 708         let allow_mpp = if let Some(features) = &payee.features {
 709                 features.supports_basic_mpp()
 710         } else if let Some(node) = network_nodes.get(&payee_node_id) {
 711                 if let Some(node_info) = node.announcement_info.as_ref() {
 712                         node_info.features.supports_basic_mpp()
 713                 } else { false }
 714         } else { false };
 715         log_trace!(logger, "Searching for a route from payer {} to payee {} {} MPP", our_node_pubkey,
 716                 payee.pubkey, if allow_mpp { "with" } else { "without" });
 717
 718         // Step (1).
 719         // Prepare the data we'll use for payee-to-payer search by
 720         // inserting first hops suggested by the caller as targets.
 721         // Our search will then attempt to reach them while traversing from the payee node.
 722         let mut first_hop_targets: HashMap<_, Vec<&ChannelDetails>> =
 723                 HashMap::with_capacity(if first_hops.is_some() { first_hops.as_ref().unwrap().len() } else { 0 });
 724         if let Some(hops) = first_hops {
 725                 for chan in hops {
 726                         if chan.short_channel_id.is_none() {
 727                                 panic!("first_hops should be filled in with usable channels, not pending ones");
 728                         }
 729                         if chan.counterparty.node_id == *our_node_pubkey {
 730                                 return Err(LightningError{err: "First hop cannot have our_node_pubkey as a destination.".to_owned(), action: ErrorAction::IgnoreError});
 731                         }
 732                         first_hop_targets
 733                                 .entry(NodeId::from_pubkey(&chan.counterparty.node_id))
 734                                 .or_insert(Vec::new())
 735                                 .push(chan);
 736                 }
 737                 if first_hop_targets.is_empty() {
 738                         return Err(LightningError{err: "Cannot route when there are no outbound routes away from us".to_owned(), action: ErrorAction::IgnoreError});
 739                 }
 740         }
 741
 742         // The main heap containing all candidate next-hops sorted by their score (max(A* fee,
 743         // htlc_minimum)). Ideally this would be a heap which allowed cheap score reduction instead of
 744         // adding duplicate entries when we find a better path to a given node.
 745         let mut targets = BinaryHeap::new();
 746
 747         // Map from node_id to information about the best current path to that node, including feerate
 748         // information.
 749         let mut dist = HashMap::with_capacity(network_nodes.len());
 750
 751         // During routing, if we ignore a path due to an htlc_minimum_msat limit, we set this,
 752         // indicating that we may wish to try again with a higher value, potentially paying to meet an
 753         // htlc_minimum with extra fees while still finding a cheaper path.
 754         let mut hit_minimum_limit;
 755
 756         // When arranging a route, we select multiple paths so that we can make a multi-path payment.
 757         // We start with a path_value of the exact amount we want, and if that generates a route we may
 758         // return it immediately. Otherwise, we don't stop searching for paths until we have 3x the
 759         // amount we want in total across paths, selecting the best subset at the end.
 760         const ROUTE_CAPACITY_PROVISION_FACTOR: u64 = 3;
 761         let recommended_value_msat = final_value_msat * ROUTE_CAPACITY_PROVISION_FACTOR as u64;
 762         let mut path_value_msat = final_value_msat;
 763
 764         // We don't want multiple paths (as per MPP) share liquidity of the same channels.
 765         // This map allows paths to be aware of the channel use by other paths in the same call.
 766         // This would help to make a better path finding decisions and not "overbook" channels.
 767         // It is unaware of the directions (except for `outbound_capacity_msat` in `first_hops`).
 768         let mut bookkeeped_channels_liquidity_available_msat = HashMap::with_capacity(network_nodes.len());
 769
 770         // Keeping track of how much value we already collected across other paths. Helps to decide:
 771         // - how much a new path should be transferring (upper bound);
 772         // - whether a channel should be disregarded because
 773         //   it's available liquidity is too small comparing to how much more we need to collect;
 774         // - when we want to stop looking for new paths.
 775         let mut already_collected_value_msat = 0;
 776
 777         log_trace!(logger, "Building path from {} (payee) to {} (us/payer) for value {} msat.", payee.pubkey, our_node_pubkey, final_value_msat);
 778
 779         macro_rules! add_entry {
 780                 // Adds entry which goes from $src_node_id to $dest_node_id over the $candidate hop.
 781                 // $next_hops_fee_msat represents the fees paid for using all the channel *after* this one,
 782                 // since that value has to be transferred over this channel.
 783                 // Returns whether this channel caused an update to `targets`.
 784                 ( $candidate: expr, $src_node_id: expr, $dest_node_id: expr, $next_hops_fee_msat: expr,
 785                    $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr, $next_hops_path_penalty_msat: expr ) => { {
 786                         // We "return" whether we updated the path at the end, via this:
 787                         let mut did_add_update_path_to_src_node = false;
 788                         // Channels to self should not be used. This is more of belt-and-suspenders, because in
 789                         // practice these cases should be caught earlier:
 790                         // - for regular channels at channel announcement (TODO)
 791                         // - for first and last hops early in get_route
 792                         if $src_node_id != $dest_node_id {
 793                                 let short_channel_id = $candidate.short_channel_id();
 794                                 let available_liquidity_msat = bookkeeped_channels_liquidity_available_msat
 795                                         .entry(short_channel_id)
 796                                         .or_insert_with(|| $candidate.effective_capacity().as_msat());
 797
 798                                 // It is tricky to substract $next_hops_fee_msat from available liquidity here.
 799                                 // It may be misleading because we might later choose to reduce the value transferred
 800                                 // over these channels, and the channel which was insufficient might become sufficient.
 801                                 // Worst case: we drop a good channel here because it can't cover the high following
 802                                 // fees caused by one expensive channel, but then this channel could have been used
 803                                 // if the amount being transferred over this path is lower.
 804                                 // We do this for now, but this is a subject for removal.
 805                                 if let Some(available_value_contribution_msat) = available_liquidity_msat.checked_sub($next_hops_fee_msat) {
 806
 807                                         // Routing Fragmentation Mitigation heuristic:
 808                                         //
 809                                         // Routing fragmentation across many payment paths increases the overall routing
 810                                         // fees as you have irreducible routing fees per-link used (`fee_base_msat`).
 811                                         // Taking too many smaller paths also increases the chance of payment failure.
 812                                         // Thus to avoid this effect, we require from our collected links to provide
 813                                         // at least a minimal contribution to the recommended value yet-to-be-fulfilled.
 814                                         //
 815                                         // This requirement is currently 5% of the remaining-to-be-collected value.
 816                                         // This means as we successfully advance in our collection,
 817                                         // the absolute liquidity contribution is lowered,
 818                                         // thus increasing the number of potential channels to be selected.
 819
 820                                         // Derive the minimal liquidity contribution with a ratio of 20 (5%, rounded up)
 821                                         // or 100% if we're not allowed to do multipath payments.
 822                                         let minimal_value_contribution_msat: u64 = if allow_mpp {
 823                                                 (recommended_value_msat - already_collected_value_msat + 19) / 20
 824                                         } else {
 825                                                 final_value_msat
 826                                         };
 827                                         // Verify the liquidity offered by this channel complies to the minimal contribution.
 828                                         let contributes_sufficient_value = available_value_contribution_msat >= minimal_value_contribution_msat;
 829
 830                                         let value_contribution_msat = cmp::min(available_value_contribution_msat, $next_hops_value_contribution);
 831                                         // Includes paying fees for the use of the following channels.
 832                                         let amount_to_transfer_over_msat: u64 = match value_contribution_msat.checked_add($next_hops_fee_msat) {
 833                                                 Some(result) => result,
 834                                                 // Can't overflow due to how the values were computed right above.
 835                                                 None => unreachable!(),
 836                                         };
 837                                         #[allow(unused_comparisons)] // $next_hops_path_htlc_minimum_msat is 0 in some calls so rustc complains
 838                                         let over_path_minimum_msat = amount_to_transfer_over_msat >= $candidate.htlc_minimum_msat() &&
 839                                                 amount_to_transfer_over_msat >= $next_hops_path_htlc_minimum_msat;
 840
 841                                         // If HTLC minimum is larger than the amount we're going to transfer, we shouldn't
 842                                         // bother considering this channel.
 843                                         // Since we're choosing amount_to_transfer_over_msat as maximum possible, it can
 844                                         // be only reduced later (not increased), so this channel should just be skipped
 845                                         // as not sufficient.
 846                                         if !over_path_minimum_msat {
 847                                                 hit_minimum_limit = true;
 848                                         } else if contributes_sufficient_value {
 849                                                 // Note that low contribution here (limited by available_liquidity_msat)
 850                                                 // might violate htlc_minimum_msat on the hops which are next along the
 851                                                 // payment path (upstream to the payee). To avoid that, we recompute path
 852                                                 // path fees knowing the final path contribution after constructing it.
 853                                                 let path_htlc_minimum_msat = compute_fees($next_hops_path_htlc_minimum_msat, $candidate.fees())
 854                                                         .and_then(|fee_msat| fee_msat.checked_add($next_hops_path_htlc_minimum_msat))
 855                                                         .map(|fee_msat| cmp::max(fee_msat, $candidate.htlc_minimum_msat()))
 856                                                         .unwrap_or_else(|| u64::max_value());
 857                                                 let hm_entry = dist.entry($src_node_id);
 858                                                 let old_entry = hm_entry.or_insert_with(|| {
 859                                                         // If there was previously no known way to access the source node
 860                                                         // (recall it goes payee-to-payer) of short_channel_id, first add a
 861                                                         // semi-dummy record just to compute the fees to reach the source node.
 862                                                         // This will affect our decision on selecting short_channel_id
 863                                                         // as a way to reach the $dest_node_id.
 864                                                         let mut fee_base_msat = u32::max_value();
 865                                                         let mut fee_proportional_millionths = u32::max_value();
 866                                                         if let Some(Some(fees)) = network_nodes.get(&$src_node_id).map(|node| node.lowest_inbound_channel_fees) {
 867                                                                 fee_base_msat = fees.base_msat;
 868                                                                 fee_proportional_millionths = fees.proportional_millionths;
 869                                                         }
 870                                                         PathBuildingHop {
 871                                                                 node_id: $dest_node_id.clone(),
 872                                                                 short_channel_id: 0,
 873                                                                 channel_features: $candidate.features(),
 874                                                                 fee_msat: 0,
 875                                                                 cltv_expiry_delta: 0,
 876                                                                 src_lowest_inbound_fees: RoutingFees {
 877                                                                         base_msat: fee_base_msat,
 878                                                                         proportional_millionths: fee_proportional_millionths,
 879                                                                 },
 880                                                                 channel_fees: $candidate.fees(),
 881                                                                 next_hops_fee_msat: u64::max_value(),
 882                                                                 hop_use_fee_msat: u64::max_value(),
 883                                                                 total_fee_msat: u64::max_value(),
 884                                                                 htlc_minimum_msat: $candidate.htlc_minimum_msat(),
 885                                                                 path_htlc_minimum_msat,
 886                                                                 path_penalty_msat: u64::max_value(),
 887                                                                 was_processed: false,
 888                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 889                                                                 value_contribution_msat,
 890                                                         }
 891                                                 });
 892
 893                                                 #[allow(unused_mut)] // We only use the mut in cfg(test)
 894                                                 let mut should_process = !old_entry.was_processed;
 895                                                 #[cfg(any(test, feature = "fuzztarget"))]
 896                                                 {
 897                                                         // In test/fuzzing builds, we do extra checks to make sure the skipping
 898                                                         // of already-seen nodes only happens in cases we expect (see below).
 899                                                         if !should_process { should_process = true; }
 900                                                 }
 901
 902                                                 if should_process {
 903                                                         let mut hop_use_fee_msat = 0;
 904                                                         let mut total_fee_msat = $next_hops_fee_msat;
 905
 906                                                         // Ignore hop_use_fee_msat for channel-from-us as we assume all channels-from-us
 907                                                         // will have the same effective-fee
 908                                                         if $src_node_id != our_node_id {
 909                                                                 match compute_fees(amount_to_transfer_over_msat, $candidate.fees()) {
 910                                                                         // max_value means we'll always fail
 911                                                                         // the old_entry.total_fee_msat > total_fee_msat check
 912                                                                         None => total_fee_msat = u64::max_value(),
 913                                                                         Some(fee_msat) => {
 914                                                                                 hop_use_fee_msat = fee_msat;
 915                                                                                 total_fee_msat += hop_use_fee_msat;
 916                                                                                 // When calculating the lowest inbound fees to a node, we
 917                                                                                 // calculate fees here not based on the actual value we think
 918                                                                                 // will flow over this channel, but on the minimum value that
 919                                                                                 // we'll accept flowing over it. The minimum accepted value
 920                                                                                 // is a constant through each path collection run, ensuring
 921                                                                                 // consistent basis. Otherwise we may later find a
 922                                                                                 // different path to the source node that is more expensive,
 923                                                                                 // but which we consider to be cheaper because we are capacity
 924                                                                                 // constrained and the relative fee becomes lower.
 925                                                                                 match compute_fees(minimal_value_contribution_msat, old_entry.src_lowest_inbound_fees)
 926                                                                                                 .map(|a| a.checked_add(total_fee_msat)) {
 927                                                                                         Some(Some(v)) => {
 928                                                                                                 total_fee_msat = v;
 929                                                                                         },
 930                                                                                         _ => {
 931                                                                                                 total_fee_msat = u64::max_value();
 932                                                                                         }
 933                                                                                 };
 934                                                                         }
 935                                                                 }
 936                                                         }
 937
 938                                                         let path_penalty_msat = $next_hops_path_penalty_msat.checked_add(
 939                                                                 scorer.channel_penalty_msat(short_channel_id, amount_to_transfer_over_msat, *available_liquidity_msat,
 940                                                                         &$src_node_id, &$dest_node_id)).unwrap_or_else(|| u64::max_value());
 941                                                         let new_graph_node = RouteGraphNode {
 942                                                                 node_id: $src_node_id,
 943                                                                 lowest_fee_to_peer_through_node: total_fee_msat,
 944                                                                 lowest_fee_to_node: $next_hops_fee_msat as u64 + hop_use_fee_msat,
 945                                                                 value_contribution_msat: value_contribution_msat,
 946                                                                 path_htlc_minimum_msat,
 947                                                                 path_penalty_msat,
 948                                                         };
 949
 950                                                         // Update the way of reaching $src_node_id with the given short_channel_id (from $dest_node_id),
 951                                                         // if this way is cheaper than the already known
 952                                                         // (considering the cost to "reach" this channel from the route destination,
 953                                                         // the cost of using this channel,
 954                                                         // and the cost of routing to the source node of this channel).
 955                                                         // Also, consider that htlc_minimum_msat_difference, because we might end up
 956                                                         // paying it. Consider the following exploit:
 957                                                         // we use 2 paths to transfer 1.5 BTC. One of them is 0-fee normal 1 BTC path,
 958                                                         // and for the other one we picked a 1sat-fee path with htlc_minimum_msat of
 959                                                         // 1 BTC. Now, since the latter is more expensive, we gonna try to cut it
 960                                                         // by 0.5 BTC, but then match htlc_minimum_msat by paying a fee of 0.5 BTC
 961                                                         // to this channel.
 962                                                         // Ideally the scoring could be smarter (e.g. 0.5*htlc_minimum_msat here),
 963                                                         // but it may require additional tracking - we don't want to double-count
 964                                                         // the fees included in $next_hops_path_htlc_minimum_msat, but also
 965                                                         // can't use something that may decrease on future hops.
 966                                                         let old_cost = cmp::max(old_entry.total_fee_msat, old_entry.path_htlc_minimum_msat)
 967                                                                 .checked_add(old_entry.path_penalty_msat)
 968                                                                 .unwrap_or_else(|| u64::max_value());
 969                                                         let new_cost = cmp::max(total_fee_msat, path_htlc_minimum_msat)
 970                                                                 .checked_add(path_penalty_msat)
 971                                                                 .unwrap_or_else(|| u64::max_value());
 972
 973                                                         if !old_entry.was_processed && new_cost < old_cost {
 974                                                                 targets.push(new_graph_node);
 975                                                                 old_entry.next_hops_fee_msat = $next_hops_fee_msat;
 976                                                                 old_entry.hop_use_fee_msat = hop_use_fee_msat;
 977                                                                 old_entry.total_fee_msat = total_fee_msat;
 978                                                                 old_entry.node_id = $dest_node_id.clone();
 979                                                                 old_entry.short_channel_id = short_channel_id;
 980                                                                 old_entry.channel_features = $candidate.features();
 981                                                                 old_entry.fee_msat = 0; // This value will be later filled with hop_use_fee_msat of the following channel
 982                                                                 old_entry.cltv_expiry_delta = $candidate.cltv_expiry_delta();
 983                                                                 old_entry.channel_fees = $candidate.fees();
 984                                                                 old_entry.htlc_minimum_msat = $candidate.htlc_minimum_msat();
 985                                                                 old_entry.path_htlc_minimum_msat = path_htlc_minimum_msat;
 986                                                                 old_entry.path_penalty_msat = path_penalty_msat;
 987                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 988                                                                 {
 989                                                                         old_entry.value_contribution_msat = value_contribution_msat;
 990                                                                 }
 991                                                                 did_add_update_path_to_src_node = true;
 992                                                         } else if old_entry.was_processed && new_cost < old_cost {
 993                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 994                                                                 {
 995                                                                         // If we're skipping processing a node which was previously
 996                                                                         // processed even though we found another path to it with a
 997                                                                         // cheaper fee, check that it was because the second path we
 998                                                                         // found (which we are processing now) has a lower value
 999                                                                         // contribution due to an HTLC minimum limit.
1000                                                                         //
1001                                                                         // e.g. take a graph with two paths from node 1 to node 2, one
1002                                                                         // through channel A, and one through channel B. Channel A and
1003                                                                         // B are both in the to-process heap, with their scores set by
1004                                                                         // a higher htlc_minimum than fee.
1005                                                                         // Channel A is processed first, and the channels onwards from
1006                                                                         // node 1 are added to the to-process heap. Thereafter, we pop
1007                                                                         // Channel B off of the heap, note that it has a much more
1008                                                                         // restrictive htlc_maximum_msat, and recalculate the fees for
1009                                                                         // all of node 1's channels using the new, reduced, amount.
1010                                                                         //
1011                                                                         // This would be bogus - we'd be selecting a higher-fee path
1012                                                                         // with a lower htlc_maximum_msat instead of the one we'd
1013                                                                         // already decided to use.
1014                                                                         debug_assert!(path_htlc_minimum_msat < old_entry.path_htlc_minimum_msat);
1015                                                                         debug_assert!(
1016                                                                                 value_contribution_msat + path_penalty_msat <
1017                                                                                 old_entry.value_contribution_msat + old_entry.path_penalty_msat
1018                                                                         );
1019                                                                 }
1020                                                         }
1021                                                 }
1022                                         }
1023                                 }
1024                         }
1025                         did_add_update_path_to_src_node
1026                 } }
1027         }
1028
1029         let empty_node_features = NodeFeatures::empty();
1030         // Find ways (channels with destination) to reach a given node and store them
1031         // in the corresponding data structures (routing graph etc).
1032         // $fee_to_target_msat represents how much it costs to reach to this node from the payee,
1033         // meaning how much will be paid in fees after this node (to the best of our knowledge).
1034         // This data can later be helpful to optimize routing (pay lower fees).
1035         macro_rules! add_entries_to_cheapest_to_target_node {
1036                 ( $node: expr, $node_id: expr, $fee_to_target_msat: expr, $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr, $next_hops_path_penalty_msat: expr ) => {
1037                         let skip_node = if let Some(elem) = dist.get_mut(&$node_id) {
1038                                 let was_processed = elem.was_processed;
1039                                 elem.was_processed = true;
1040                                 was_processed
1041                         } else {
1042                                 // Entries are added to dist in add_entry!() when there is a channel from a node.
1043                                 // Because there are no channels from payee, it will not have a dist entry at this point.
1044                                 // If we're processing any other node, it is always be the result of a channel from it.
1045                                 assert_eq!($node_id, payee_node_id);
1046                                 false
1047                         };
1048
1049                         if !skip_node {
1050                                 if let Some(first_channels) = first_hop_targets.get(&$node_id) {
1051                                         for details in first_channels {
1052                                                 let candidate = CandidateRouteHop::FirstHop { details };
1053                                                 add_entry!(candidate, our_node_id, $node_id, $fee_to_target_msat, $next_hops_value_contribution, $next_hops_path_htlc_minimum_msat, $next_hops_path_penalty_msat);
1054                                         }
1055                                 }
1056
1057                                 let features = if let Some(node_info) = $node.announcement_info.as_ref() {
1058                                         &node_info.features
1059                                 } else {
1060                                         &empty_node_features
1061                                 };
1062
1063                                 if !features.requires_unknown_bits() {
1064                                         for chan_id in $node.channels.iter() {
1065                                                 let chan = network_channels.get(chan_id).unwrap();
1066                                                 if !chan.features.requires_unknown_bits() {
1067                                                         let directed_channel = chan.directed_to(&$node_id);
1068                                                         let source = directed_channel.source();
1069                                                         let target = directed_channel.target();
1070                                                         if first_hops.is_none() || *source != our_node_id {
1071                                                                 let (channel, direction) = directed_channel.into_parts();
1072                                                                 if let Some(direction) = direction {
1073                                                                         if direction.enabled {
1074                                                                                 let candidate = CandidateRouteHop::PublicHop {
1075                                                                                         short_channel_id: *chan_id,
1076                                                                                         channel,
1077                                                                                         direction,
1078                                                                                 };
1079                                                                                 add_entry!(candidate, *source, *target, $fee_to_target_msat, $next_hops_value_contribution, $next_hops_path_htlc_minimum_msat, $next_hops_path_penalty_msat);
1080                                                                         }
1081                                                                 }
1082                                                         }
1083                                                 }
1084                                         }
1085                                 }
1086                         }
1087                 };
1088         }
1089
1090         let mut payment_paths = Vec::<PaymentPath>::new();
1091
1092         // TODO: diversify by nodes (so that all paths aren't doomed if one node is offline).
1093         'paths_collection: loop {
1094                 // For every new path, start from scratch, except
1095                 // bookkeeped_channels_liquidity_available_msat, which will improve
1096                 // the further iterations of path finding. Also don't erase first_hop_targets.
1097                 targets.clear();
1098                 dist.clear();
1099                 hit_minimum_limit = false;
1100
1101                 // If first hop is a private channel and the only way to reach the payee, this is the only
1102                 // place where it could be added.
1103                 if let Some(first_channels) = first_hop_targets.get(&payee_node_id) {
1104                         for details in first_channels {
1105                                 let candidate = CandidateRouteHop::FirstHop { details };
1106                                 let added = add_entry!(candidate, our_node_id, payee_node_id, 0, path_value_msat, 0, 0u64);
1107                                 log_trace!(logger, "{} direct route to payee via SCID {}", if added { "Added" } else { "Skipped" }, candidate.short_channel_id());
1108                         }
1109                 }
1110
1111                 // Add the payee as a target, so that the payee-to-payer
1112                 // search algorithm knows what to start with.
1113                 match network_nodes.get(&payee_node_id) {
1114                         // The payee is not in our network graph, so nothing to add here.
1115                         // There is still a chance of reaching them via last_hops though,
1116                         // so don't yet fail the payment here.
1117                         // If not, targets.pop() will not even let us enter the loop in step 2.
1118                         None => {},
1119                         Some(node) => {
1120                                 add_entries_to_cheapest_to_target_node!(node, payee_node_id, 0, path_value_msat, 0, 0u64);
1121                         },
1122                 }
1123
1124                 // Step (2).
1125                 // If a caller provided us with last hops, add them to routing targets. Since this happens
1126                 // earlier than general path finding, they will be somewhat prioritized, although currently
1127                 // it matters only if the fees are exactly the same.
1128                 for route in payee.route_hints.iter().filter(|route| !route.0.is_empty()) {
1129                         let first_hop_in_route = &(route.0)[0];
1130                         let have_hop_src_in_graph =
1131                                 // Only add the hops in this route to our candidate set if either
1132                                 // we have a direct channel to the first hop or the first hop is
1133                                 // in the regular network graph.
1134                                 first_hop_targets.get(&NodeId::from_pubkey(&first_hop_in_route.src_node_id)).is_some() ||
1135                                 network_nodes.get(&NodeId::from_pubkey(&first_hop_in_route.src_node_id)).is_some();
1136                         if have_hop_src_in_graph {
1137                                 // We start building the path from reverse, i.e., from payee
1138                                 // to the first RouteHintHop in the path.
1139                                 let hop_iter = route.0.iter().rev();
1140                                 let prev_hop_iter = core::iter::once(&payee.pubkey).chain(
1141                                         route.0.iter().skip(1).rev().map(|hop| &hop.src_node_id));
1142                                 let mut hop_used = true;
1143                                 let mut aggregate_next_hops_fee_msat: u64 = 0;
1144                                 let mut aggregate_next_hops_path_htlc_minimum_msat: u64 = 0;
1145                                 let mut aggregate_next_hops_path_penalty_msat: u64 = 0;
1146
1147                                 for (idx, (hop, prev_hop_id)) in hop_iter.zip(prev_hop_iter).enumerate() {
1148                                         let source = NodeId::from_pubkey(&hop.src_node_id);
1149                                         let target = NodeId::from_pubkey(&prev_hop_id);
1150                                         let candidate = network_channels
1151                                                 .get(&hop.short_channel_id)
1152                                                 .map(|channel| channel.as_directed(&source, &target).into_parts())
1153                                                 .and_then(|(channel, direction)| {
1154                                                         direction.map(|direction|
1155                                                                 CandidateRouteHop::PublicHop {
1156                                                                         short_channel_id: hop.short_channel_id,
1157                                                                         channel,
1158                                                                         direction,
1159                                                                 })
1160                                                 })
1161                                                 .unwrap_or_else(|| CandidateRouteHop::PrivateHop { hint: hop });
1162                                         let capacity_msat = candidate.effective_capacity().as_msat();
1163                                         aggregate_next_hops_path_penalty_msat = aggregate_next_hops_path_penalty_msat
1164                                                 .checked_add(scorer.channel_penalty_msat(hop.short_channel_id, final_value_msat, capacity_msat, &source, &target))
1165                                                 .unwrap_or_else(|| u64::max_value());
1166
1167                                         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) {
1168                                                 // If this hop was not used then there is no use checking the preceding hops
1169                                                 // in the RouteHint. We can break by just searching for a direct channel between
1170                                                 // last checked hop and first_hop_targets
1171                                                 hop_used = false;
1172                                         }
1173
1174                                         // Searching for a direct channel between last checked hop and first_hop_targets
1175                                         if let Some(first_channels) = first_hop_targets.get(&NodeId::from_pubkey(&prev_hop_id)) {
1176                                                 for details in first_channels {
1177                                                         let candidate = CandidateRouteHop::FirstHop { details };
1178                                                         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);
1179                                                 }
1180                                         }
1181
1182                                         if !hop_used {
1183                                                 break;
1184                                         }
1185
1186                                         // In the next values of the iterator, the aggregate fees already reflects
1187                                         // the sum of value sent from payer (final_value_msat) and routing fees
1188                                         // for the last node in the RouteHint. We need to just add the fees to
1189                                         // route through the current node so that the preceeding node (next iteration)
1190                                         // can use it.
1191                                         let hops_fee = compute_fees(aggregate_next_hops_fee_msat + final_value_msat, hop.fees)
1192                                                 .map_or(None, |inc| inc.checked_add(aggregate_next_hops_fee_msat));
1193                                         aggregate_next_hops_fee_msat = if let Some(val) = hops_fee { val } else { break; };
1194
1195                                         let hop_htlc_minimum_msat = candidate.htlc_minimum_msat();
1196                                         let hop_htlc_minimum_msat_inc = if let Some(val) = compute_fees(aggregate_next_hops_path_htlc_minimum_msat, hop.fees) { val } else { break; };
1197                                         let hops_path_htlc_minimum = aggregate_next_hops_path_htlc_minimum_msat
1198                                                 .checked_add(hop_htlc_minimum_msat_inc);
1199                                         aggregate_next_hops_path_htlc_minimum_msat = if let Some(val) = hops_path_htlc_minimum { cmp::max(hop_htlc_minimum_msat, val) } else { break; };
1200
1201                                         if idx == route.0.len() - 1 {
1202                                                 // The last hop in this iterator is the first hop in
1203                                                 // overall RouteHint.
1204                                                 // If this hop connects to a node with which we have a direct channel,
1205                                                 // ignore the network graph and, if the last hop was added, add our
1206                                                 // direct channel to the candidate set.
1207                                                 //
1208                                                 // Note that we *must* check if the last hop was added as `add_entry`
1209                                                 // always assumes that the third argument is a node to which we have a
1210                                                 // path.
1211                                                 if let Some(first_channels) = first_hop_targets.get(&NodeId::from_pubkey(&hop.src_node_id)) {
1212                                                         for details in first_channels {
1213                                                                 let candidate = CandidateRouteHop::FirstHop { details };
1214                                                                 add_entry!(candidate, our_node_id, NodeId::from_pubkey(&hop.src_node_id), aggregate_next_hops_fee_msat, path_value_msat, aggregate_next_hops_path_htlc_minimum_msat, aggregate_next_hops_path_penalty_msat);
1215                                                         }
1216                                                 }
1217                                         }
1218                                 }
1219                         }
1220                 }
1221
1222                 log_trace!(logger, "Starting main path collection loop with {} nodes pre-filled from first/last hops.", targets.len());
1223
1224                 // At this point, targets are filled with the data from first and
1225                 // last hops communicated by the caller, and the payment receiver.
1226                 let mut found_new_path = false;
1227
1228                 // Step (3).
1229                 // If this loop terminates due the exhaustion of targets, two situations are possible:
1230                 // - not enough outgoing liquidity:
1231                 //   0 < already_collected_value_msat < final_value_msat
1232                 // - enough outgoing liquidity:
1233                 //   final_value_msat <= already_collected_value_msat < recommended_value_msat
1234                 // Both these cases (and other cases except reaching recommended_value_msat) mean that
1235                 // paths_collection will be stopped because found_new_path==false.
1236                 // This is not necessarily a routing failure.
1237                 'path_construction: while let Some(RouteGraphNode { node_id, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat, path_penalty_msat, .. }) = targets.pop() {
1238
1239                         // Since we're going payee-to-payer, hitting our node as a target means we should stop
1240                         // traversing the graph and arrange the path out of what we found.
1241                         if node_id == our_node_id {
1242                                 let mut new_entry = dist.remove(&our_node_id).unwrap();
1243                                 let mut ordered_hops = vec!((new_entry.clone(), NodeFeatures::empty()));
1244
1245                                 'path_walk: loop {
1246                                         let mut features_set = false;
1247                                         if let Some(first_channels) = first_hop_targets.get(&ordered_hops.last().unwrap().0.node_id) {
1248                                                 for details in first_channels {
1249                                                         if details.short_channel_id.unwrap() == ordered_hops.last().unwrap().0.short_channel_id {
1250                                                                 ordered_hops.last_mut().unwrap().1 = details.counterparty.features.to_context();
1251                                                                 features_set = true;
1252                                                                 break;
1253                                                         }
1254                                                 }
1255                                         }
1256                                         if !features_set {
1257                                                 if let Some(node) = network_nodes.get(&ordered_hops.last().unwrap().0.node_id) {
1258                                                         if let Some(node_info) = node.announcement_info.as_ref() {
1259                                                                 ordered_hops.last_mut().unwrap().1 = node_info.features.clone();
1260                                                         } else {
1261                                                                 ordered_hops.last_mut().unwrap().1 = NodeFeatures::empty();
1262                                                         }
1263                                                 } else {
1264                                                         // We should be able to fill in features for everything except the last
1265                                                         // hop, if the last hop was provided via a BOLT 11 invoice (though we
1266                                                         // should be able to extend it further as BOLT 11 does have feature
1267                                                         // flags for the last hop node itself).
1268                                                         assert!(ordered_hops.last().unwrap().0.node_id == payee_node_id);
1269                                                 }
1270                                         }
1271
1272                                         // Means we succesfully traversed from the payer to the payee, now
1273                                         // save this path for the payment route. Also, update the liquidity
1274                                         // remaining on the used hops, so that we take them into account
1275                                         // while looking for more paths.
1276                                         if ordered_hops.last().unwrap().0.node_id == payee_node_id {
1277                                                 break 'path_walk;
1278                                         }
1279
1280                                         new_entry = match dist.remove(&ordered_hops.last().unwrap().0.node_id) {
1281                                                 Some(payment_hop) => payment_hop,
1282                                                 // We can't arrive at None because, if we ever add an entry to targets,
1283                                                 // we also fill in the entry in dist (see add_entry!).
1284                                                 None => unreachable!(),
1285                                         };
1286                                         // We "propagate" the fees one hop backward (topologically) here,
1287                                         // so that fees paid for a HTLC forwarding on the current channel are
1288                                         // associated with the previous channel (where they will be subtracted).
1289                                         ordered_hops.last_mut().unwrap().0.fee_msat = new_entry.hop_use_fee_msat;
1290                                         ordered_hops.last_mut().unwrap().0.cltv_expiry_delta = new_entry.cltv_expiry_delta;
1291                                         ordered_hops.push((new_entry.clone(), NodeFeatures::empty()));
1292                                 }
1293                                 ordered_hops.last_mut().unwrap().0.fee_msat = value_contribution_msat;
1294                                 ordered_hops.last_mut().unwrap().0.hop_use_fee_msat = 0;
1295                                 ordered_hops.last_mut().unwrap().0.cltv_expiry_delta = final_cltv_expiry_delta;
1296
1297                                 log_trace!(logger, "Found a path back to us from the target with {} hops contributing up to {} msat: {:?}",
1298                                         ordered_hops.len(), value_contribution_msat, ordered_hops);
1299
1300                                 let mut payment_path = PaymentPath {hops: ordered_hops};
1301
1302                                 // We could have possibly constructed a slightly inconsistent path: since we reduce
1303                                 // value being transferred along the way, we could have violated htlc_minimum_msat
1304                                 // on some channels we already passed (assuming dest->source direction). Here, we
1305                                 // recompute the fees again, so that if that's the case, we match the currently
1306                                 // underpaid htlc_minimum_msat with fees.
1307                                 payment_path.update_value_and_recompute_fees(cmp::min(value_contribution_msat, final_value_msat));
1308
1309                                 // Since a path allows to transfer as much value as
1310                                 // the smallest channel it has ("bottleneck"), we should recompute
1311                                 // the fees so sender HTLC don't overpay fees when traversing
1312                                 // larger channels than the bottleneck. This may happen because
1313                                 // when we were selecting those channels we were not aware how much value
1314                                 // this path will transfer, and the relative fee for them
1315                                 // might have been computed considering a larger value.
1316                                 // Remember that we used these channels so that we don't rely
1317                                 // on the same liquidity in future paths.
1318                                 let mut prevented_redundant_path_selection = false;
1319                                 for (payment_hop, _) in payment_path.hops.iter() {
1320                                         let channel_liquidity_available_msat = bookkeeped_channels_liquidity_available_msat.get_mut(&payment_hop.short_channel_id).unwrap();
1321                                         let mut spent_on_hop_msat = value_contribution_msat;
1322                                         let next_hops_fee_msat = payment_hop.next_hops_fee_msat;
1323                                         spent_on_hop_msat += next_hops_fee_msat;
1324                                         if spent_on_hop_msat == *channel_liquidity_available_msat {
1325                                                 // If this path used all of this channel's available liquidity, we know
1326                                                 // this path will not be selected again in the next loop iteration.
1327                                                 prevented_redundant_path_selection = true;
1328                                         }
1329                                         *channel_liquidity_available_msat -= spent_on_hop_msat;
1330                                 }
1331                                 if !prevented_redundant_path_selection {
1332                                         // If we weren't capped by hitting a liquidity limit on a channel in the path,
1333                                         // we'll probably end up picking the same path again on the next iteration.
1334                                         // Decrease the available liquidity of a hop in the middle of the path.
1335                                         let victim_scid = payment_path.hops[(payment_path.hops.len() - 1) / 2].0.short_channel_id;
1336                                         log_trace!(logger, "Disabling channel {} for future path building iterations to avoid duplicates.", victim_scid);
1337                                         let victim_liquidity = bookkeeped_channels_liquidity_available_msat.get_mut(&victim_scid).unwrap();
1338                                         *victim_liquidity = 0;
1339                                 }
1340
1341                                 // Track the total amount all our collected paths allow to send so that we:
1342                                 // - know when to stop looking for more paths
1343                                 // - know which of the hops are useless considering how much more sats we need
1344                                 //   (contributes_sufficient_value)
1345                                 already_collected_value_msat += value_contribution_msat;
1346
1347                                 payment_paths.push(payment_path);
1348                                 found_new_path = true;
1349                                 break 'path_construction;
1350                         }
1351
1352                         // If we found a path back to the payee, we shouldn't try to process it again. This is
1353                         // the equivalent of the `elem.was_processed` check in
1354                         // add_entries_to_cheapest_to_target_node!() (see comment there for more info).
1355                         if node_id == payee_node_id { continue 'path_construction; }
1356
1357                         // Otherwise, since the current target node is not us,
1358                         // keep "unrolling" the payment graph from payee to payer by
1359                         // finding a way to reach the current target from the payer side.
1360                         match network_nodes.get(&node_id) {
1361                                 None => {},
1362                                 Some(node) => {
1363                                         add_entries_to_cheapest_to_target_node!(node, node_id, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat, path_penalty_msat);
1364                                 },
1365                         }
1366                 }
1367
1368                 if !allow_mpp {
1369                         // If we don't support MPP, no use trying to gather more value ever.
1370                         break 'paths_collection;
1371                 }
1372
1373                 // Step (4).
1374                 // Stop either when the recommended value is reached or if no new path was found in this
1375                 // iteration.
1376                 // In the latter case, making another path finding attempt won't help,
1377                 // because we deterministically terminated the search due to low liquidity.
1378                 if already_collected_value_msat >= recommended_value_msat || !found_new_path {
1379                         log_trace!(logger, "Have now collected {} msat (seeking {} msat) in paths. Last path loop {} a new path.",
1380                                 already_collected_value_msat, recommended_value_msat, if found_new_path { "found" } else { "did not find" });
1381                         break 'paths_collection;
1382                 } else if found_new_path && already_collected_value_msat == final_value_msat && payment_paths.len() == 1 {
1383                         // Further, if this was our first walk of the graph, and we weren't limited by an
1384                         // htlc_minimum_msat, return immediately because this path should suffice. If we were
1385                         // limited by an htlc_minimum_msat value, find another path with a higher value,
1386                         // potentially allowing us to pay fees to meet the htlc_minimum on the new path while
1387                         // still keeping a lower total fee than this path.
1388                         if !hit_minimum_limit {
1389                                 log_trace!(logger, "Collected exactly our payment amount on the first pass, without hitting an htlc_minimum_msat limit, exiting.");
1390                                 break 'paths_collection;
1391                         }
1392                         log_trace!(logger, "Collected our payment amount on the first pass, but running again to collect extra paths with a potentially higher limit.");
1393                         path_value_msat = recommended_value_msat;
1394                 }
1395         }
1396
1397         // Step (5).
1398         if payment_paths.len() == 0 {
1399                 return Err(LightningError{err: "Failed to find a path to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1400         }
1401
1402         if already_collected_value_msat < final_value_msat {
1403                 return Err(LightningError{err: "Failed to find a sufficient route to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1404         }
1405
1406         // Sort by total fees and take the best paths.
1407         payment_paths.sort_by_key(|path| path.get_total_fee_paid_msat());
1408         if payment_paths.len() > 50 {
1409                 payment_paths.truncate(50);
1410         }
1411
1412         // Draw multiple sufficient routes by randomly combining the selected paths.
1413         let mut drawn_routes = Vec::new();
1414         for i in 0..payment_paths.len() {
1415                 let mut cur_route = Vec::<PaymentPath>::new();
1416                 let mut aggregate_route_value_msat = 0;
1417
1418                 // Step (6).
1419                 // TODO: real random shuffle
1420                 // Currently just starts with i_th and goes up to i-1_th in a looped way.
1421                 let cur_payment_paths = [&payment_paths[i..], &payment_paths[..i]].concat();
1422
1423                 // Step (7).
1424                 for payment_path in cur_payment_paths {
1425                         cur_route.push(payment_path.clone());
1426                         aggregate_route_value_msat += payment_path.get_value_msat();
1427                         if aggregate_route_value_msat > final_value_msat {
1428                                 // Last path likely overpaid. Substract it from the most expensive
1429                                 // (in terms of proportional fee) path in this route and recompute fees.
1430                                 // This might be not the most economically efficient way, but fewer paths
1431                                 // also makes routing more reliable.
1432                                 let mut overpaid_value_msat = aggregate_route_value_msat - final_value_msat;
1433
1434                                 // First, drop some expensive low-value paths entirely if possible.
1435                                 // Sort by value so that we drop many really-low values first, since
1436                                 // fewer paths is better: the payment is less likely to fail.
1437                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1438                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1439                                 cur_route.sort_by_key(|path| path.get_value_msat());
1440                                 // We should make sure that at least 1 path left.
1441                                 let mut paths_left = cur_route.len();
1442                                 cur_route.retain(|path| {
1443                                         if paths_left == 1 {
1444                                                 return true
1445                                         }
1446                                         let mut keep = true;
1447                                         let path_value_msat = path.get_value_msat();
1448                                         if path_value_msat <= overpaid_value_msat {
1449                                                 keep = false;
1450                                                 overpaid_value_msat -= path_value_msat;
1451                                                 paths_left -= 1;
1452                                         }
1453                                         keep
1454                                 });
1455
1456                                 if overpaid_value_msat == 0 {
1457                                         break;
1458                                 }
1459
1460                                 assert!(cur_route.len() > 0);
1461
1462                                 // Step (8).
1463                                 // Now, substract the overpaid value from the most-expensive path.
1464                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1465                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1466                                 cur_route.sort_by_key(|path| { path.hops.iter().map(|hop| hop.0.channel_fees.proportional_millionths as u64).sum::<u64>() });
1467                                 let expensive_payment_path = cur_route.first_mut().unwrap();
1468                                 // We already dropped all the small channels above, meaning all the
1469                                 // remaining channels are larger than remaining overpaid_value_msat.
1470                                 // Thus, this can't be negative.
1471                                 let expensive_path_new_value_msat = expensive_payment_path.get_value_msat() - overpaid_value_msat;
1472                                 expensive_payment_path.update_value_and_recompute_fees(expensive_path_new_value_msat);
1473                                 break;
1474                         }
1475                 }
1476                 drawn_routes.push(cur_route);
1477         }
1478
1479         // Step (9).
1480         // Select the best route by lowest total fee.
1481         drawn_routes.sort_by_key(|paths| paths.iter().map(|path| path.get_total_fee_paid_msat()).sum::<u64>());
1482         let mut selected_paths = Vec::<Vec<Result<RouteHop, LightningError>>>::new();
1483         for payment_path in drawn_routes.first().unwrap() {
1484                 selected_paths.push(payment_path.hops.iter().map(|(payment_hop, node_features)| {
1485                         Ok(RouteHop {
1486                                 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)})?,
1487                                 node_features: node_features.clone(),
1488                                 short_channel_id: payment_hop.short_channel_id,
1489                                 channel_features: payment_hop.channel_features.clone(),
1490                                 fee_msat: payment_hop.fee_msat,
1491                                 cltv_expiry_delta: payment_hop.cltv_expiry_delta,
1492                         })
1493                 }).collect());
1494         }
1495
1496         if let Some(features) = &payee.features {
1497                 for path in selected_paths.iter_mut() {
1498                         if let Ok(route_hop) = path.last_mut().unwrap() {
1499                                 route_hop.node_features = features.to_context();
1500                         }
1501                 }
1502         }
1503
1504         let route = Route {
1505                 paths: selected_paths.into_iter().map(|path| path.into_iter().collect()).collect::<Result<Vec<_>, _>>()?,
1506                 payee: Some(payee.clone()),
1507         };
1508         log_info!(logger, "Got route to {}: {}", payee.pubkey, log_route!(route));
1509         Ok(route)
1510 }
1511
1512 #[cfg(test)]
1513 mod tests {
1514         use routing::scoring::Score;
1515         use routing::network_graph::{NetworkGraph, NetGraphMsgHandler, NodeId};
1516         use routing::router::{get_route, Payee, Route, RouteHint, RouteHintHop, RouteHop, RoutingFees};
1517         use chain::transaction::OutPoint;
1518         use ln::features::{ChannelFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
1519         use ln::msgs::{ErrorAction, LightningError, OptionalField, UnsignedChannelAnnouncement, ChannelAnnouncement, RoutingMessageHandler,
1520            NodeAnnouncement, UnsignedNodeAnnouncement, ChannelUpdate, UnsignedChannelUpdate};
1521         use ln::channelmanager;
1522         use util::test_utils;
1523         use util::ser::Writeable;
1524         #[cfg(c_bindings)]
1525         use util::ser::Writer;
1526
1527         use bitcoin::hashes::sha256d::Hash as Sha256dHash;
1528         use bitcoin::hashes::Hash;
1529         use bitcoin::network::constants::Network;
1530         use bitcoin::blockdata::constants::genesis_block;
1531         use bitcoin::blockdata::script::Builder;
1532         use bitcoin::blockdata::opcodes;
1533         use bitcoin::blockdata::transaction::TxOut;
1534
1535         use hex;
1536
1537         use bitcoin::secp256k1::key::{PublicKey,SecretKey};
1538         use bitcoin::secp256k1::{Secp256k1, All};
1539
1540         use prelude::*;
1541         use sync::{self, Arc};
1542
1543         fn get_channel_details(short_channel_id: Option<u64>, node_id: PublicKey,
1544                         features: InitFeatures, outbound_capacity_msat: u64) -> channelmanager::ChannelDetails {
1545                 channelmanager::ChannelDetails {
1546                         channel_id: [0; 32],
1547                         counterparty: channelmanager::ChannelCounterparty {
1548                                 features,
1549                                 node_id,
1550                                 unspendable_punishment_reserve: 0,
1551                                 forwarding_info: None,
1552                         },
1553                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
1554                         short_channel_id,
1555                         channel_value_satoshis: 0,
1556                         user_channel_id: 0,
1557                         balance_msat: 0,
1558                         outbound_capacity_msat,
1559                         inbound_capacity_msat: 42,
1560                         unspendable_punishment_reserve: None,
1561                         confirmations_required: None,
1562                         force_close_spend_delay: None,
1563                         is_outbound: true, is_funding_locked: true,
1564                         is_usable: true, is_public: true,
1565                 }
1566         }
1567
1568         // Using the same keys for LN and BTC ids
1569         fn add_channel(
1570                 net_graph_msg_handler: &NetGraphMsgHandler<Arc<NetworkGraph>, Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>,
1571                 secp_ctx: &Secp256k1<All>, node_1_privkey: &SecretKey, node_2_privkey: &SecretKey, features: ChannelFeatures, short_channel_id: u64
1572         ) {
1573                 let node_id_1 = PublicKey::from_secret_key(&secp_ctx, node_1_privkey);
1574                 let node_id_2 = PublicKey::from_secret_key(&secp_ctx, node_2_privkey);
1575
1576                 let unsigned_announcement = UnsignedChannelAnnouncement {
1577                         features,
1578                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1579                         short_channel_id,
1580                         node_id_1,
1581                         node_id_2,
1582                         bitcoin_key_1: node_id_1,
1583                         bitcoin_key_2: node_id_2,
1584                         excess_data: Vec::new(),
1585                 };
1586
1587                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1588                 let valid_announcement = ChannelAnnouncement {
1589                         node_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1590                         node_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1591                         bitcoin_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1592                         bitcoin_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1593                         contents: unsigned_announcement.clone(),
1594                 };
1595                 match net_graph_msg_handler.handle_channel_announcement(&valid_announcement) {
1596                         Ok(res) => assert!(res),
1597                         _ => panic!()
1598                 };
1599         }
1600
1601         fn update_channel(
1602                 net_graph_msg_handler: &NetGraphMsgHandler<Arc<NetworkGraph>, Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>,
1603                 secp_ctx: &Secp256k1<All>, node_privkey: &SecretKey, update: UnsignedChannelUpdate
1604         ) {
1605                 let msghash = hash_to_message!(&Sha256dHash::hash(&update.encode()[..])[..]);
1606                 let valid_channel_update = ChannelUpdate {
1607                         signature: secp_ctx.sign(&msghash, node_privkey),
1608                         contents: update.clone()
1609                 };
1610
1611                 match net_graph_msg_handler.handle_channel_update(&valid_channel_update) {
1612                         Ok(res) => assert!(res),
1613                         Err(_) => panic!()
1614                 };
1615         }
1616
1617         fn add_or_update_node(
1618                 net_graph_msg_handler: &NetGraphMsgHandler<Arc<NetworkGraph>, Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>,
1619                 secp_ctx: &Secp256k1<All>, node_privkey: &SecretKey, features: NodeFeatures, timestamp: u32
1620         ) {
1621                 let node_id = PublicKey::from_secret_key(&secp_ctx, node_privkey);
1622                 let unsigned_announcement = UnsignedNodeAnnouncement {
1623                         features,
1624                         timestamp,
1625                         node_id,
1626                         rgb: [0; 3],
1627                         alias: [0; 32],
1628                         addresses: Vec::new(),
1629                         excess_address_data: Vec::new(),
1630                         excess_data: Vec::new(),
1631                 };
1632                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1633                 let valid_announcement = NodeAnnouncement {
1634                         signature: secp_ctx.sign(&msghash, node_privkey),
1635                         contents: unsigned_announcement.clone()
1636                 };
1637
1638                 match net_graph_msg_handler.handle_node_announcement(&valid_announcement) {
1639                         Ok(_) => (),
1640                         Err(_) => panic!()
1641                 };
1642         }
1643
1644         fn get_nodes(secp_ctx: &Secp256k1<All>) -> (SecretKey, PublicKey, Vec<SecretKey>, Vec<PublicKey>) {
1645                 let privkeys: Vec<SecretKey> = (2..10).map(|i| {
1646                         SecretKey::from_slice(&hex::decode(format!("{:02}", i).repeat(32)).unwrap()[..]).unwrap()
1647                 }).collect();
1648
1649                 let pubkeys = privkeys.iter().map(|secret| PublicKey::from_secret_key(&secp_ctx, secret)).collect();
1650
1651                 let our_privkey = SecretKey::from_slice(&hex::decode("01".repeat(32)).unwrap()[..]).unwrap();
1652                 let our_id = PublicKey::from_secret_key(&secp_ctx, &our_privkey);
1653
1654                 (our_privkey, our_id, privkeys, pubkeys)
1655         }
1656
1657         fn id_to_feature_flags(id: u8) -> Vec<u8> {
1658                 // Set the feature flags to the id'th odd (ie non-required) feature bit so that we can
1659                 // test for it later.
1660                 let idx = (id - 1) * 2 + 1;
1661                 if idx > 8*3 {
1662                         vec![1 << (idx - 8*3), 0, 0, 0]
1663                 } else if idx > 8*2 {
1664                         vec![1 << (idx - 8*2), 0, 0]
1665                 } else if idx > 8*1 {
1666                         vec![1 << (idx - 8*1), 0]
1667                 } else {
1668                         vec![1 << idx]
1669                 }
1670         }
1671
1672         fn build_graph() -> (
1673                 Secp256k1<All>,
1674                 sync::Arc<NetworkGraph>,
1675                 NetGraphMsgHandler<sync::Arc<NetworkGraph>, sync::Arc<test_utils::TestChainSource>, sync::Arc<crate::util::test_utils::TestLogger>>,
1676                 sync::Arc<test_utils::TestChainSource>,
1677                 sync::Arc<test_utils::TestLogger>,
1678         ) {
1679                 let secp_ctx = Secp256k1::new();
1680                 let logger = Arc::new(test_utils::TestLogger::new());
1681                 let chain_monitor = Arc::new(test_utils::TestChainSource::new(Network::Testnet));
1682                 let network_graph = Arc::new(NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash()));
1683                 let net_graph_msg_handler = NetGraphMsgHandler::new(Arc::clone(&network_graph), None, Arc::clone(&logger));
1684                 // Build network from our_id to node6:
1685                 //
1686                 //        -1(1)2-  node0  -1(3)2-
1687                 //       /                       \
1688                 // our_id -1(12)2- node7 -1(13)2--- node2
1689                 //       \                       /
1690                 //        -1(2)2-  node1  -1(4)2-
1691                 //
1692                 //
1693                 // chan1  1-to-2: disabled
1694                 // chan1  2-to-1: enabled, 0 fee
1695                 //
1696                 // chan2  1-to-2: enabled, ignored fee
1697                 // chan2  2-to-1: enabled, 0 fee
1698                 //
1699                 // chan3  1-to-2: enabled, 0 fee
1700                 // chan3  2-to-1: enabled, 100 msat fee
1701                 //
1702                 // chan4  1-to-2: enabled, 100% fee
1703                 // chan4  2-to-1: enabled, 0 fee
1704                 //
1705                 // chan12 1-to-2: enabled, ignored fee
1706                 // chan12 2-to-1: enabled, 0 fee
1707                 //
1708                 // chan13 1-to-2: enabled, 200% fee
1709                 // chan13 2-to-1: enabled, 0 fee
1710                 //
1711                 //
1712                 //       -1(5)2- node3 -1(8)2--
1713                 //       |         2          |
1714                 //       |       (11)         |
1715                 //      /          1           \
1716                 // node2--1(6)2- node4 -1(9)2--- node6 (not in global route map)
1717                 //      \                      /
1718                 //       -1(7)2- node5 -1(10)2-
1719                 //
1720                 // Channels 5, 8, 9 and 10 are private channels.
1721                 //
1722                 // chan5  1-to-2: enabled, 100 msat fee
1723                 // chan5  2-to-1: enabled, 0 fee
1724                 //
1725                 // chan6  1-to-2: enabled, 0 fee
1726                 // chan6  2-to-1: enabled, 0 fee
1727                 //
1728                 // chan7  1-to-2: enabled, 100% fee
1729                 // chan7  2-to-1: enabled, 0 fee
1730                 //
1731                 // chan8  1-to-2: enabled, variable fee (0 then 1000 msat)
1732                 // chan8  2-to-1: enabled, 0 fee
1733                 //
1734                 // chan9  1-to-2: enabled, 1001 msat fee
1735                 // chan9  2-to-1: enabled, 0 fee
1736                 //
1737                 // chan10 1-to-2: enabled, 0 fee
1738                 // chan10 2-to-1: enabled, 0 fee
1739                 //
1740                 // chan11 1-to-2: enabled, 0 fee
1741                 // chan11 2-to-1: enabled, 0 fee
1742
1743                 let (our_privkey, _, privkeys, _) = get_nodes(&secp_ctx);
1744
1745                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[0], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
1746                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1747                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1748                         short_channel_id: 1,
1749                         timestamp: 1,
1750                         flags: 1,
1751                         cltv_expiry_delta: 0,
1752                         htlc_minimum_msat: 0,
1753                         htlc_maximum_msat: OptionalField::Absent,
1754                         fee_base_msat: 0,
1755                         fee_proportional_millionths: 0,
1756                         excess_data: Vec::new()
1757                 });
1758
1759                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
1760
1761                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
1762                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1763                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1764                         short_channel_id: 2,
1765                         timestamp: 1,
1766                         flags: 0,
1767                         cltv_expiry_delta: u16::max_value(),
1768                         htlc_minimum_msat: 0,
1769                         htlc_maximum_msat: OptionalField::Absent,
1770                         fee_base_msat: u32::max_value(),
1771                         fee_proportional_millionths: u32::max_value(),
1772                         excess_data: Vec::new()
1773                 });
1774                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1775                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1776                         short_channel_id: 2,
1777                         timestamp: 1,
1778                         flags: 1,
1779                         cltv_expiry_delta: 0,
1780                         htlc_minimum_msat: 0,
1781                         htlc_maximum_msat: OptionalField::Absent,
1782                         fee_base_msat: 0,
1783                         fee_proportional_millionths: 0,
1784                         excess_data: Vec::new()
1785                 });
1786
1787                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
1788
1789                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[7], ChannelFeatures::from_le_bytes(id_to_feature_flags(12)), 12);
1790                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1791                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1792                         short_channel_id: 12,
1793                         timestamp: 1,
1794                         flags: 0,
1795                         cltv_expiry_delta: u16::max_value(),
1796                         htlc_minimum_msat: 0,
1797                         htlc_maximum_msat: OptionalField::Absent,
1798                         fee_base_msat: u32::max_value(),
1799                         fee_proportional_millionths: u32::max_value(),
1800                         excess_data: Vec::new()
1801                 });
1802                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1803                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1804                         short_channel_id: 12,
1805                         timestamp: 1,
1806                         flags: 1,
1807                         cltv_expiry_delta: 0,
1808                         htlc_minimum_msat: 0,
1809                         htlc_maximum_msat: OptionalField::Absent,
1810                         fee_base_msat: 0,
1811                         fee_proportional_millionths: 0,
1812                         excess_data: Vec::new()
1813                 });
1814
1815                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], NodeFeatures::from_le_bytes(id_to_feature_flags(8)), 0);
1816
1817                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
1818                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1819                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1820                         short_channel_id: 3,
1821                         timestamp: 1,
1822                         flags: 0,
1823                         cltv_expiry_delta: (3 << 8) | 1,
1824                         htlc_minimum_msat: 0,
1825                         htlc_maximum_msat: OptionalField::Absent,
1826                         fee_base_msat: 0,
1827                         fee_proportional_millionths: 0,
1828                         excess_data: Vec::new()
1829                 });
1830                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1831                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1832                         short_channel_id: 3,
1833                         timestamp: 1,
1834                         flags: 1,
1835                         cltv_expiry_delta: (3 << 8) | 2,
1836                         htlc_minimum_msat: 0,
1837                         htlc_maximum_msat: OptionalField::Absent,
1838                         fee_base_msat: 100,
1839                         fee_proportional_millionths: 0,
1840                         excess_data: Vec::new()
1841                 });
1842
1843                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
1844                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1845                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1846                         short_channel_id: 4,
1847                         timestamp: 1,
1848                         flags: 0,
1849                         cltv_expiry_delta: (4 << 8) | 1,
1850                         htlc_minimum_msat: 0,
1851                         htlc_maximum_msat: OptionalField::Absent,
1852                         fee_base_msat: 0,
1853                         fee_proportional_millionths: 1000000,
1854                         excess_data: Vec::new()
1855                 });
1856                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1857                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1858                         short_channel_id: 4,
1859                         timestamp: 1,
1860                         flags: 1,
1861                         cltv_expiry_delta: (4 << 8) | 2,
1862                         htlc_minimum_msat: 0,
1863                         htlc_maximum_msat: OptionalField::Absent,
1864                         fee_base_msat: 0,
1865                         fee_proportional_millionths: 0,
1866                         excess_data: Vec::new()
1867                 });
1868
1869                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(13)), 13);
1870                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1871                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1872                         short_channel_id: 13,
1873                         timestamp: 1,
1874                         flags: 0,
1875                         cltv_expiry_delta: (13 << 8) | 1,
1876                         htlc_minimum_msat: 0,
1877                         htlc_maximum_msat: OptionalField::Absent,
1878                         fee_base_msat: 0,
1879                         fee_proportional_millionths: 2000000,
1880                         excess_data: Vec::new()
1881                 });
1882                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1883                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1884                         short_channel_id: 13,
1885                         timestamp: 1,
1886                         flags: 1,
1887                         cltv_expiry_delta: (13 << 8) | 2,
1888                         htlc_minimum_msat: 0,
1889                         htlc_maximum_msat: OptionalField::Absent,
1890                         fee_base_msat: 0,
1891                         fee_proportional_millionths: 0,
1892                         excess_data: Vec::new()
1893                 });
1894
1895                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
1896
1897                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
1898                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1899                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1900                         short_channel_id: 6,
1901                         timestamp: 1,
1902                         flags: 0,
1903                         cltv_expiry_delta: (6 << 8) | 1,
1904                         htlc_minimum_msat: 0,
1905                         htlc_maximum_msat: OptionalField::Absent,
1906                         fee_base_msat: 0,
1907                         fee_proportional_millionths: 0,
1908                         excess_data: Vec::new()
1909                 });
1910                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1911                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1912                         short_channel_id: 6,
1913                         timestamp: 1,
1914                         flags: 1,
1915                         cltv_expiry_delta: (6 << 8) | 2,
1916                         htlc_minimum_msat: 0,
1917                         htlc_maximum_msat: OptionalField::Absent,
1918                         fee_base_msat: 0,
1919                         fee_proportional_millionths: 0,
1920                         excess_data: Vec::new(),
1921                 });
1922
1923                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(11)), 11);
1924                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1925                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1926                         short_channel_id: 11,
1927                         timestamp: 1,
1928                         flags: 0,
1929                         cltv_expiry_delta: (11 << 8) | 1,
1930                         htlc_minimum_msat: 0,
1931                         htlc_maximum_msat: OptionalField::Absent,
1932                         fee_base_msat: 0,
1933                         fee_proportional_millionths: 0,
1934                         excess_data: Vec::new()
1935                 });
1936                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
1937                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1938                         short_channel_id: 11,
1939                         timestamp: 1,
1940                         flags: 1,
1941                         cltv_expiry_delta: (11 << 8) | 2,
1942                         htlc_minimum_msat: 0,
1943                         htlc_maximum_msat: OptionalField::Absent,
1944                         fee_base_msat: 0,
1945                         fee_proportional_millionths: 0,
1946                         excess_data: Vec::new()
1947                 });
1948
1949                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(5)), 0);
1950
1951                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
1952
1953                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[5], ChannelFeatures::from_le_bytes(id_to_feature_flags(7)), 7);
1954                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1955                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1956                         short_channel_id: 7,
1957                         timestamp: 1,
1958                         flags: 0,
1959                         cltv_expiry_delta: (7 << 8) | 1,
1960                         htlc_minimum_msat: 0,
1961                         htlc_maximum_msat: OptionalField::Absent,
1962                         fee_base_msat: 0,
1963                         fee_proportional_millionths: 1000000,
1964                         excess_data: Vec::new()
1965                 });
1966                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[5], UnsignedChannelUpdate {
1967                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1968                         short_channel_id: 7,
1969                         timestamp: 1,
1970                         flags: 1,
1971                         cltv_expiry_delta: (7 << 8) | 2,
1972                         htlc_minimum_msat: 0,
1973                         htlc_maximum_msat: OptionalField::Absent,
1974                         fee_base_msat: 0,
1975                         fee_proportional_millionths: 0,
1976                         excess_data: Vec::new()
1977                 });
1978
1979                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[5], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
1980
1981                 (secp_ctx, network_graph, net_graph_msg_handler, chain_monitor, logger)
1982         }
1983
1984         #[test]
1985         fn simple_route_test() {
1986                 let (secp_ctx, network_graph, _, _, logger) = build_graph();
1987                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1988                 let payee = Payee::from_node_id(nodes[2]);
1989                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
1990
1991                 // Simple route to 2 via 1
1992
1993                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &payee, &network_graph, None, 0, 42, Arc::clone(&logger), &scorer) {
1994                         assert_eq!(err, "Cannot send a payment of 0 msat");
1995                 } else { panic!(); }
1996
1997                 let route = get_route(&our_id, &payee, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
1998                 assert_eq!(route.paths[0].len(), 2);
1999
2000                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2001                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2002                 assert_eq!(route.paths[0][0].fee_msat, 100);
2003                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2004                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2005                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2006
2007                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2008                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2009                 assert_eq!(route.paths[0][1].fee_msat, 100);
2010                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2011                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2012                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2013         }
2014
2015         #[test]
2016         fn invalid_first_hop_test() {
2017                 let (secp_ctx, network_graph, _, _, logger) = build_graph();
2018                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2019                 let payee = Payee::from_node_id(nodes[2]);
2020                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2021
2022                 // Simple route to 2 via 1
2023
2024                 let our_chans = vec![get_channel_details(Some(2), our_id, InitFeatures::from_le_bytes(vec![0b11]), 100000)];
2025
2026                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &payee, &network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 100, 42, Arc::clone(&logger), &scorer) {
2027                         assert_eq!(err, "First hop cannot have our_node_pubkey as a destination.");
2028                 } else { panic!(); }
2029
2030                 let route = get_route(&our_id, &payee, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
2031                 assert_eq!(route.paths[0].len(), 2);
2032         }
2033
2034         #[test]
2035         fn htlc_minimum_test() {
2036                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
2037                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2038                 let payee = Payee::from_node_id(nodes[2]);
2039                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2040
2041                 // Simple route to 2 via 1
2042
2043                 // Disable other paths
2044                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2045                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2046                         short_channel_id: 12,
2047                         timestamp: 2,
2048                         flags: 2, // to disable
2049                         cltv_expiry_delta: 0,
2050                         htlc_minimum_msat: 0,
2051                         htlc_maximum_msat: OptionalField::Absent,
2052                         fee_base_msat: 0,
2053                         fee_proportional_millionths: 0,
2054                         excess_data: Vec::new()
2055                 });
2056                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2057                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2058                         short_channel_id: 3,
2059                         timestamp: 2,
2060                         flags: 2, // to disable
2061                         cltv_expiry_delta: 0,
2062                         htlc_minimum_msat: 0,
2063                         htlc_maximum_msat: OptionalField::Absent,
2064                         fee_base_msat: 0,
2065                         fee_proportional_millionths: 0,
2066                         excess_data: Vec::new()
2067                 });
2068                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2069                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2070                         short_channel_id: 13,
2071                         timestamp: 2,
2072                         flags: 2, // to disable
2073                         cltv_expiry_delta: 0,
2074                         htlc_minimum_msat: 0,
2075                         htlc_maximum_msat: OptionalField::Absent,
2076                         fee_base_msat: 0,
2077                         fee_proportional_millionths: 0,
2078                         excess_data: Vec::new()
2079                 });
2080                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2081                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2082                         short_channel_id: 6,
2083                         timestamp: 2,
2084                         flags: 2, // to disable
2085                         cltv_expiry_delta: 0,
2086                         htlc_minimum_msat: 0,
2087                         htlc_maximum_msat: OptionalField::Absent,
2088                         fee_base_msat: 0,
2089                         fee_proportional_millionths: 0,
2090                         excess_data: Vec::new()
2091                 });
2092                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2093                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2094                         short_channel_id: 7,
2095                         timestamp: 2,
2096                         flags: 2, // to disable
2097                         cltv_expiry_delta: 0,
2098                         htlc_minimum_msat: 0,
2099                         htlc_maximum_msat: OptionalField::Absent,
2100                         fee_base_msat: 0,
2101                         fee_proportional_millionths: 0,
2102                         excess_data: Vec::new()
2103                 });
2104
2105                 // Check against amount_to_transfer_over_msat.
2106                 // Set minimal HTLC of 200_000_000 msat.
2107                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2108                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2109                         short_channel_id: 2,
2110                         timestamp: 3,
2111                         flags: 0,
2112                         cltv_expiry_delta: 0,
2113                         htlc_minimum_msat: 200_000_000,
2114                         htlc_maximum_msat: OptionalField::Absent,
2115                         fee_base_msat: 0,
2116                         fee_proportional_millionths: 0,
2117                         excess_data: Vec::new()
2118                 });
2119
2120                 // Second hop only allows to forward 199_999_999 at most, thus not allowing the first hop to
2121                 // be used.
2122                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2123                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2124                         short_channel_id: 4,
2125                         timestamp: 3,
2126                         flags: 0,
2127                         cltv_expiry_delta: 0,
2128                         htlc_minimum_msat: 0,
2129                         htlc_maximum_msat: OptionalField::Present(199_999_999),
2130                         fee_base_msat: 0,
2131                         fee_proportional_millionths: 0,
2132                         excess_data: Vec::new()
2133                 });
2134
2135                 // Not possible to send 199_999_999, because the minimum on channel=2 is 200_000_000.
2136                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &payee, &network_graph, None, 199_999_999, 42, Arc::clone(&logger), &scorer) {
2137                         assert_eq!(err, "Failed to find a path to the given destination");
2138                 } else { panic!(); }
2139
2140                 // Lift the restriction on the first hop.
2141                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2142                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2143                         short_channel_id: 2,
2144                         timestamp: 4,
2145                         flags: 0,
2146                         cltv_expiry_delta: 0,
2147                         htlc_minimum_msat: 0,
2148                         htlc_maximum_msat: OptionalField::Absent,
2149                         fee_base_msat: 0,
2150                         fee_proportional_millionths: 0,
2151                         excess_data: Vec::new()
2152                 });
2153
2154                 // A payment above the minimum should pass
2155                 let route = get_route(&our_id, &payee, &network_graph, None, 199_999_999, 42, Arc::clone(&logger), &scorer).unwrap();
2156                 assert_eq!(route.paths[0].len(), 2);
2157         }
2158
2159         #[test]
2160         fn htlc_minimum_overpay_test() {
2161                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
2162                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2163                 let payee = Payee::from_node_id(nodes[2]).with_features(InvoiceFeatures::known());
2164                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2165
2166                 // A route to node#2 via two paths.
2167                 // One path allows transferring 35-40 sats, another one also allows 35-40 sats.
2168                 // Thus, they can't send 60 without overpaying.
2169                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2170                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2171                         short_channel_id: 2,
2172                         timestamp: 2,
2173                         flags: 0,
2174                         cltv_expiry_delta: 0,
2175                         htlc_minimum_msat: 35_000,
2176                         htlc_maximum_msat: OptionalField::Present(40_000),
2177                         fee_base_msat: 0,
2178                         fee_proportional_millionths: 0,
2179                         excess_data: Vec::new()
2180                 });
2181                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2182                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2183                         short_channel_id: 12,
2184                         timestamp: 3,
2185                         flags: 0,
2186                         cltv_expiry_delta: 0,
2187                         htlc_minimum_msat: 35_000,
2188                         htlc_maximum_msat: OptionalField::Present(40_000),
2189                         fee_base_msat: 0,
2190                         fee_proportional_millionths: 0,
2191                         excess_data: Vec::new()
2192                 });
2193
2194                 // Make 0 fee.
2195                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2196                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2197                         short_channel_id: 13,
2198                         timestamp: 2,
2199                         flags: 0,
2200                         cltv_expiry_delta: 0,
2201                         htlc_minimum_msat: 0,
2202                         htlc_maximum_msat: OptionalField::Absent,
2203                         fee_base_msat: 0,
2204                         fee_proportional_millionths: 0,
2205                         excess_data: Vec::new()
2206                 });
2207                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2208                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2209                         short_channel_id: 4,
2210                         timestamp: 2,
2211                         flags: 0,
2212                         cltv_expiry_delta: 0,
2213                         htlc_minimum_msat: 0,
2214                         htlc_maximum_msat: OptionalField::Absent,
2215                         fee_base_msat: 0,
2216                         fee_proportional_millionths: 0,
2217                         excess_data: Vec::new()
2218                 });
2219
2220                 // Disable other paths
2221                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2222                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2223                         short_channel_id: 1,
2224                         timestamp: 3,
2225                         flags: 2, // to disable
2226                         cltv_expiry_delta: 0,
2227                         htlc_minimum_msat: 0,
2228                         htlc_maximum_msat: OptionalField::Absent,
2229                         fee_base_msat: 0,
2230                         fee_proportional_millionths: 0,
2231                         excess_data: Vec::new()
2232                 });
2233
2234                 let route = get_route(&our_id, &payee, &network_graph, None, 60_000, 42, Arc::clone(&logger), &scorer).unwrap();
2235                 // Overpay fees to hit htlc_minimum_msat.
2236                 let overpaid_fees = route.paths[0][0].fee_msat + route.paths[1][0].fee_msat;
2237                 // TODO: this could be better balanced to overpay 10k and not 15k.
2238                 assert_eq!(overpaid_fees, 15_000);
2239
2240                 // Now, test that if there are 2 paths, a "cheaper" by fee path wouldn't be prioritized
2241                 // while taking even more fee to match htlc_minimum_msat.
2242                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2243                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2244                         short_channel_id: 12,
2245                         timestamp: 4,
2246                         flags: 0,
2247                         cltv_expiry_delta: 0,
2248                         htlc_minimum_msat: 65_000,
2249                         htlc_maximum_msat: OptionalField::Present(80_000),
2250                         fee_base_msat: 0,
2251                         fee_proportional_millionths: 0,
2252                         excess_data: Vec::new()
2253                 });
2254                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2255                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2256                         short_channel_id: 2,
2257                         timestamp: 3,
2258                         flags: 0,
2259                         cltv_expiry_delta: 0,
2260                         htlc_minimum_msat: 0,
2261                         htlc_maximum_msat: OptionalField::Absent,
2262                         fee_base_msat: 0,
2263                         fee_proportional_millionths: 0,
2264                         excess_data: Vec::new()
2265                 });
2266                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2267                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2268                         short_channel_id: 4,
2269                         timestamp: 4,
2270                         flags: 0,
2271                         cltv_expiry_delta: 0,
2272                         htlc_minimum_msat: 0,
2273                         htlc_maximum_msat: OptionalField::Absent,
2274                         fee_base_msat: 0,
2275                         fee_proportional_millionths: 100_000,
2276                         excess_data: Vec::new()
2277                 });
2278
2279                 let route = get_route(&our_id, &payee, &network_graph, None, 60_000, 42, Arc::clone(&logger), &scorer).unwrap();
2280                 // Fine to overpay for htlc_minimum_msat if it allows us to save fee.
2281                 assert_eq!(route.paths.len(), 1);
2282                 assert_eq!(route.paths[0][0].short_channel_id, 12);
2283                 let fees = route.paths[0][0].fee_msat;
2284                 assert_eq!(fees, 5_000);
2285
2286                 let route = get_route(&our_id, &payee, &network_graph, None, 50_000, 42, Arc::clone(&logger), &scorer).unwrap();
2287                 // Not fine to overpay for htlc_minimum_msat if it requires paying more than fee on
2288                 // the other channel.
2289                 assert_eq!(route.paths.len(), 1);
2290                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2291                 let fees = route.paths[0][0].fee_msat;
2292                 assert_eq!(fees, 5_000);
2293         }
2294
2295         #[test]
2296         fn disable_channels_test() {
2297                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
2298                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2299                 let payee = Payee::from_node_id(nodes[2]);
2300                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2301
2302                 // // Disable channels 4 and 12 by flags=2
2303                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2304                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2305                         short_channel_id: 4,
2306                         timestamp: 2,
2307                         flags: 2, // to disable
2308                         cltv_expiry_delta: 0,
2309                         htlc_minimum_msat: 0,
2310                         htlc_maximum_msat: OptionalField::Absent,
2311                         fee_base_msat: 0,
2312                         fee_proportional_millionths: 0,
2313                         excess_data: Vec::new()
2314                 });
2315                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2316                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2317                         short_channel_id: 12,
2318                         timestamp: 2,
2319                         flags: 2, // to disable
2320                         cltv_expiry_delta: 0,
2321                         htlc_minimum_msat: 0,
2322                         htlc_maximum_msat: OptionalField::Absent,
2323                         fee_base_msat: 0,
2324                         fee_proportional_millionths: 0,
2325                         excess_data: Vec::new()
2326                 });
2327
2328                 // If all the channels require some features we don't understand, route should fail
2329                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &payee, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer) {
2330                         assert_eq!(err, "Failed to find a path to the given destination");
2331                 } else { panic!(); }
2332
2333                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2334                 let our_chans = vec![get_channel_details(Some(42), nodes[7].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2335                 let route = get_route(&our_id, &payee, &network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 100, 42, Arc::clone(&logger), &scorer).unwrap();
2336                 assert_eq!(route.paths[0].len(), 2);
2337
2338                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2339                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2340                 assert_eq!(route.paths[0][0].fee_msat, 200);
2341                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2342                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
2343                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2344
2345                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2346                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2347                 assert_eq!(route.paths[0][1].fee_msat, 100);
2348                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2349                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2350                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2351         }
2352
2353         #[test]
2354         fn disable_node_test() {
2355                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
2356                 let (_, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2357                 let payee = Payee::from_node_id(nodes[2]);
2358                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2359
2360                 // Disable nodes 1, 2, and 8 by requiring unknown feature bits
2361                 let unknown_features = NodeFeatures::known().set_unknown_feature_required();
2362                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], unknown_features.clone(), 1);
2363                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], unknown_features.clone(), 1);
2364                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], unknown_features.clone(), 1);
2365
2366                 // If all nodes require some features we don't understand, route should fail
2367                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &payee, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer) {
2368                         assert_eq!(err, "Failed to find a path to the given destination");
2369                 } else { panic!(); }
2370
2371                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2372                 let our_chans = vec![get_channel_details(Some(42), nodes[7].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2373                 let route = get_route(&our_id, &payee, &network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 100, 42, Arc::clone(&logger), &scorer).unwrap();
2374                 assert_eq!(route.paths[0].len(), 2);
2375
2376                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2377                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2378                 assert_eq!(route.paths[0][0].fee_msat, 200);
2379                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2380                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
2381                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2382
2383                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2384                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2385                 assert_eq!(route.paths[0][1].fee_msat, 100);
2386                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2387                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2388                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2389
2390                 // Note that we don't test disabling node 3 and failing to route to it, as we (somewhat
2391                 // naively) assume that the user checked the feature bits on the invoice, which override
2392                 // the node_announcement.
2393         }
2394
2395         #[test]
2396         fn our_chans_test() {
2397                 let (secp_ctx, network_graph, _, _, logger) = build_graph();
2398                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2399                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2400
2401                 // Route to 1 via 2 and 3 because our channel to 1 is disabled
2402                 let payee = Payee::from_node_id(nodes[0]);
2403                 let route = get_route(&our_id, &payee, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
2404                 assert_eq!(route.paths[0].len(), 3);
2405
2406                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2407                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2408                 assert_eq!(route.paths[0][0].fee_msat, 200);
2409                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2410                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2411                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2412
2413                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2414                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2415                 assert_eq!(route.paths[0][1].fee_msat, 100);
2416                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (3 << 8) | 2);
2417                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2418                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2419
2420                 assert_eq!(route.paths[0][2].pubkey, nodes[0]);
2421                 assert_eq!(route.paths[0][2].short_channel_id, 3);
2422                 assert_eq!(route.paths[0][2].fee_msat, 100);
2423                 assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
2424                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(1));
2425                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(3));
2426
2427                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2428                 let payee = Payee::from_node_id(nodes[2]);
2429                 let our_chans = vec![get_channel_details(Some(42), nodes[7].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2430                 let route = get_route(&our_id, &payee, &network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 100, 42, Arc::clone(&logger), &scorer).unwrap();
2431                 assert_eq!(route.paths[0].len(), 2);
2432
2433                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2434                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2435                 assert_eq!(route.paths[0][0].fee_msat, 200);
2436                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2437                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2438                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2439
2440                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2441                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2442                 assert_eq!(route.paths[0][1].fee_msat, 100);
2443                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2444                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2445                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2446         }
2447
2448         fn last_hops(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2449                 let zero_fees = RoutingFees {
2450                         base_msat: 0,
2451                         proportional_millionths: 0,
2452                 };
2453                 vec![RouteHint(vec![RouteHintHop {
2454                         src_node_id: nodes[3],
2455                         short_channel_id: 8,
2456                         fees: zero_fees,
2457                         cltv_expiry_delta: (8 << 8) | 1,
2458                         htlc_minimum_msat: None,
2459                         htlc_maximum_msat: None,
2460                 }
2461                 ]), RouteHint(vec![RouteHintHop {
2462                         src_node_id: nodes[4],
2463                         short_channel_id: 9,
2464                         fees: RoutingFees {
2465                                 base_msat: 1001,
2466                                 proportional_millionths: 0,
2467                         },
2468                         cltv_expiry_delta: (9 << 8) | 1,
2469                         htlc_minimum_msat: None,
2470                         htlc_maximum_msat: None,
2471                 }]), RouteHint(vec![RouteHintHop {
2472                         src_node_id: nodes[5],
2473                         short_channel_id: 10,
2474                         fees: zero_fees,
2475                         cltv_expiry_delta: (10 << 8) | 1,
2476                         htlc_minimum_msat: None,
2477                         htlc_maximum_msat: None,
2478                 }])]
2479         }
2480
2481         fn last_hops_multi_private_channels(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2482                 let zero_fees = RoutingFees {
2483                         base_msat: 0,
2484                         proportional_millionths: 0,
2485                 };
2486                 vec![RouteHint(vec![RouteHintHop {
2487                         src_node_id: nodes[2],
2488                         short_channel_id: 5,
2489                         fees: RoutingFees {
2490                                 base_msat: 100,
2491                                 proportional_millionths: 0,
2492                         },
2493                         cltv_expiry_delta: (5 << 8) | 1,
2494                         htlc_minimum_msat: None,
2495                         htlc_maximum_msat: None,
2496                 }, RouteHintHop {
2497                         src_node_id: nodes[3],
2498                         short_channel_id: 8,
2499                         fees: zero_fees,
2500                         cltv_expiry_delta: (8 << 8) | 1,
2501                         htlc_minimum_msat: None,
2502                         htlc_maximum_msat: None,
2503                 }
2504                 ]), RouteHint(vec![RouteHintHop {
2505                         src_node_id: nodes[4],
2506                         short_channel_id: 9,
2507                         fees: RoutingFees {
2508                                 base_msat: 1001,
2509                                 proportional_millionths: 0,
2510                         },
2511                         cltv_expiry_delta: (9 << 8) | 1,
2512                         htlc_minimum_msat: None,
2513                         htlc_maximum_msat: None,
2514                 }]), RouteHint(vec![RouteHintHop {
2515                         src_node_id: nodes[5],
2516                         short_channel_id: 10,
2517                         fees: zero_fees,
2518                         cltv_expiry_delta: (10 << 8) | 1,
2519                         htlc_minimum_msat: None,
2520                         htlc_maximum_msat: None,
2521                 }])]
2522         }
2523
2524         #[test]
2525         fn partial_route_hint_test() {
2526                 let (secp_ctx, network_graph, _, _, logger) = build_graph();
2527                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2528                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2529
2530                 // Simple test across 2, 3, 5, and 4 via a last_hop channel
2531                 // Tests the behaviour when the RouteHint contains a suboptimal hop.
2532                 // RouteHint may be partially used by the algo to build the best path.
2533
2534                 // First check that last hop can't have its source as the payee.
2535                 let invalid_last_hop = RouteHint(vec![RouteHintHop {
2536                         src_node_id: nodes[6],
2537                         short_channel_id: 8,
2538                         fees: RoutingFees {
2539                                 base_msat: 1000,
2540                                 proportional_millionths: 0,
2541                         },
2542                         cltv_expiry_delta: (8 << 8) | 1,
2543                         htlc_minimum_msat: None,
2544                         htlc_maximum_msat: None,
2545                 }]);
2546
2547                 let mut invalid_last_hops = last_hops_multi_private_channels(&nodes);
2548                 invalid_last_hops.push(invalid_last_hop);
2549                 {
2550                         let payee = Payee::from_node_id(nodes[6]).with_route_hints(invalid_last_hops);
2551                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &payee, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer) {
2552                                 assert_eq!(err, "Route hint cannot have the payee as the source.");
2553                         } else { panic!(); }
2554                 }
2555
2556                 let payee = Payee::from_node_id(nodes[6]).with_route_hints(last_hops_multi_private_channels(&nodes));
2557                 let route = get_route(&our_id, &payee, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
2558                 assert_eq!(route.paths[0].len(), 5);
2559
2560                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2561                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2562                 assert_eq!(route.paths[0][0].fee_msat, 100);
2563                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2564                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2565                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2566
2567                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2568                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2569                 assert_eq!(route.paths[0][1].fee_msat, 0);
2570                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2571                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2572                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2573
2574                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2575                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2576                 assert_eq!(route.paths[0][2].fee_msat, 0);
2577                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2578                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2579                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2580
2581                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2582                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2583                 assert_eq!(route.paths[0][3].fee_msat, 0);
2584                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2585                 // If we have a peer in the node map, we'll use their features here since we don't have
2586                 // a way of figuring out their features from the invoice:
2587                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2588                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2589
2590                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2591                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2592                 assert_eq!(route.paths[0][4].fee_msat, 100);
2593                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2594                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2595                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2596         }
2597
2598         fn empty_last_hop(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2599                 let zero_fees = RoutingFees {
2600                         base_msat: 0,
2601                         proportional_millionths: 0,
2602                 };
2603                 vec![RouteHint(vec![RouteHintHop {
2604                         src_node_id: nodes[3],
2605                         short_channel_id: 8,
2606                         fees: zero_fees,
2607                         cltv_expiry_delta: (8 << 8) | 1,
2608                         htlc_minimum_msat: None,
2609                         htlc_maximum_msat: None,
2610                 }]), RouteHint(vec![
2611
2612                 ]), RouteHint(vec![RouteHintHop {
2613                         src_node_id: nodes[5],
2614                         short_channel_id: 10,
2615                         fees: zero_fees,
2616                         cltv_expiry_delta: (10 << 8) | 1,
2617                         htlc_minimum_msat: None,
2618                         htlc_maximum_msat: None,
2619                 }])]
2620         }
2621
2622         #[test]
2623         fn ignores_empty_last_hops_test() {
2624                 let (secp_ctx, network_graph, _, _, logger) = build_graph();
2625                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2626                 let payee = Payee::from_node_id(nodes[6]).with_route_hints(empty_last_hop(&nodes));
2627                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2628
2629                 // Test handling of an empty RouteHint passed in Invoice.
2630
2631                 let route = get_route(&our_id, &payee, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
2632                 assert_eq!(route.paths[0].len(), 5);
2633
2634                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2635                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2636                 assert_eq!(route.paths[0][0].fee_msat, 100);
2637                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2638                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2639                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2640
2641                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2642                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2643                 assert_eq!(route.paths[0][1].fee_msat, 0);
2644                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2645                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2646                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2647
2648                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2649                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2650                 assert_eq!(route.paths[0][2].fee_msat, 0);
2651                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2652                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2653                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2654
2655                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2656                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2657                 assert_eq!(route.paths[0][3].fee_msat, 0);
2658                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2659                 // If we have a peer in the node map, we'll use their features here since we don't have
2660                 // a way of figuring out their features from the invoice:
2661                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2662                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2663
2664                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2665                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2666                 assert_eq!(route.paths[0][4].fee_msat, 100);
2667                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2668                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2669                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2670         }
2671
2672         fn multi_hint_last_hops(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2673                 let zero_fees = RoutingFees {
2674                         base_msat: 0,
2675                         proportional_millionths: 0,
2676                 };
2677                 vec![RouteHint(vec![RouteHintHop {
2678                         src_node_id: nodes[2],
2679                         short_channel_id: 5,
2680                         fees: RoutingFees {
2681                                 base_msat: 100,
2682                                 proportional_millionths: 0,
2683                         },
2684                         cltv_expiry_delta: (5 << 8) | 1,
2685                         htlc_minimum_msat: None,
2686                         htlc_maximum_msat: None,
2687                 }, RouteHintHop {
2688                         src_node_id: nodes[3],
2689                         short_channel_id: 8,
2690                         fees: zero_fees,
2691                         cltv_expiry_delta: (8 << 8) | 1,
2692                         htlc_minimum_msat: None,
2693                         htlc_maximum_msat: None,
2694                 }]), RouteHint(vec![RouteHintHop {
2695                         src_node_id: nodes[5],
2696                         short_channel_id: 10,
2697                         fees: zero_fees,
2698                         cltv_expiry_delta: (10 << 8) | 1,
2699                         htlc_minimum_msat: None,
2700                         htlc_maximum_msat: None,
2701                 }])]
2702         }
2703
2704         #[test]
2705         fn multi_hint_last_hops_test() {
2706                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
2707                 let (_, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2708                 let payee = Payee::from_node_id(nodes[6]).with_route_hints(multi_hint_last_hops(&nodes));
2709                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2710                 // Test through channels 2, 3, 5, 8.
2711                 // Test shows that multiple hop hints are considered.
2712
2713                 // Disabling channels 6 & 7 by flags=2
2714                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2715                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2716                         short_channel_id: 6,
2717                         timestamp: 2,
2718                         flags: 2, // to disable
2719                         cltv_expiry_delta: 0,
2720                         htlc_minimum_msat: 0,
2721                         htlc_maximum_msat: OptionalField::Absent,
2722                         fee_base_msat: 0,
2723                         fee_proportional_millionths: 0,
2724                         excess_data: Vec::new()
2725                 });
2726                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2727                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2728                         short_channel_id: 7,
2729                         timestamp: 2,
2730                         flags: 2, // to disable
2731                         cltv_expiry_delta: 0,
2732                         htlc_minimum_msat: 0,
2733                         htlc_maximum_msat: OptionalField::Absent,
2734                         fee_base_msat: 0,
2735                         fee_proportional_millionths: 0,
2736                         excess_data: Vec::new()
2737                 });
2738
2739                 let route = get_route(&our_id, &payee, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
2740                 assert_eq!(route.paths[0].len(), 4);
2741
2742                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2743                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2744                 assert_eq!(route.paths[0][0].fee_msat, 200);
2745                 assert_eq!(route.paths[0][0].cltv_expiry_delta, 1025);
2746                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2747                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2748
2749                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2750                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2751                 assert_eq!(route.paths[0][1].fee_msat, 100);
2752                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 1281);
2753                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2754                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2755
2756                 assert_eq!(route.paths[0][2].pubkey, nodes[3]);
2757                 assert_eq!(route.paths[0][2].short_channel_id, 5);
2758                 assert_eq!(route.paths[0][2].fee_msat, 0);
2759                 assert_eq!(route.paths[0][2].cltv_expiry_delta, 2049);
2760                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(4));
2761                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &Vec::<u8>::new());
2762
2763                 assert_eq!(route.paths[0][3].pubkey, nodes[6]);
2764                 assert_eq!(route.paths[0][3].short_channel_id, 8);
2765                 assert_eq!(route.paths[0][3].fee_msat, 100);
2766                 assert_eq!(route.paths[0][3].cltv_expiry_delta, 42);
2767                 assert_eq!(route.paths[0][3].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2768                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2769         }
2770
2771         fn last_hops_with_public_channel(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2772                 let zero_fees = RoutingFees {
2773                         base_msat: 0,
2774                         proportional_millionths: 0,
2775                 };
2776                 vec![RouteHint(vec![RouteHintHop {
2777                         src_node_id: nodes[4],
2778                         short_channel_id: 11,
2779                         fees: zero_fees,
2780                         cltv_expiry_delta: (11 << 8) | 1,
2781                         htlc_minimum_msat: None,
2782                         htlc_maximum_msat: None,
2783                 }, RouteHintHop {
2784                         src_node_id: nodes[3],
2785                         short_channel_id: 8,
2786                         fees: zero_fees,
2787                         cltv_expiry_delta: (8 << 8) | 1,
2788                         htlc_minimum_msat: None,
2789                         htlc_maximum_msat: None,
2790                 }]), RouteHint(vec![RouteHintHop {
2791                         src_node_id: nodes[4],
2792                         short_channel_id: 9,
2793                         fees: RoutingFees {
2794                                 base_msat: 1001,
2795                                 proportional_millionths: 0,
2796                         },
2797                         cltv_expiry_delta: (9 << 8) | 1,
2798                         htlc_minimum_msat: None,
2799                         htlc_maximum_msat: None,
2800                 }]), RouteHint(vec![RouteHintHop {
2801                         src_node_id: nodes[5],
2802                         short_channel_id: 10,
2803                         fees: zero_fees,
2804                         cltv_expiry_delta: (10 << 8) | 1,
2805                         htlc_minimum_msat: None,
2806                         htlc_maximum_msat: None,
2807                 }])]
2808         }
2809
2810         #[test]
2811         fn last_hops_with_public_channel_test() {
2812                 let (secp_ctx, network_graph, _, _, logger) = build_graph();
2813                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2814                 let payee = Payee::from_node_id(nodes[6]).with_route_hints(last_hops_with_public_channel(&nodes));
2815                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2816                 // This test shows that public routes can be present in the invoice
2817                 // which would be handled in the same manner.
2818
2819                 let route = get_route(&our_id, &payee, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
2820                 assert_eq!(route.paths[0].len(), 5);
2821
2822                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2823                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2824                 assert_eq!(route.paths[0][0].fee_msat, 100);
2825                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2826                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2827                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2828
2829                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2830                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2831                 assert_eq!(route.paths[0][1].fee_msat, 0);
2832                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2833                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2834                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2835
2836                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2837                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2838                 assert_eq!(route.paths[0][2].fee_msat, 0);
2839                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2840                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2841                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2842
2843                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2844                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2845                 assert_eq!(route.paths[0][3].fee_msat, 0);
2846                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2847                 // If we have a peer in the node map, we'll use their features here since we don't have
2848                 // a way of figuring out their features from the invoice:
2849                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2850                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2851
2852                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2853                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2854                 assert_eq!(route.paths[0][4].fee_msat, 100);
2855                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2856                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2857                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2858         }
2859
2860         #[test]
2861         fn our_chans_last_hop_connect_test() {
2862                 let (secp_ctx, network_graph, _, _, logger) = build_graph();
2863                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2864                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2865
2866                 // Simple test with outbound channel to 4 to test that last_hops and first_hops connect
2867                 let our_chans = vec![get_channel_details(Some(42), nodes[3].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2868                 let mut last_hops = last_hops(&nodes);
2869                 let payee = Payee::from_node_id(nodes[6]).with_route_hints(last_hops.clone());
2870                 let route = get_route(&our_id, &payee, &network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 100, 42, Arc::clone(&logger), &scorer).unwrap();
2871                 assert_eq!(route.paths[0].len(), 2);
2872
2873                 assert_eq!(route.paths[0][0].pubkey, nodes[3]);
2874                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2875                 assert_eq!(route.paths[0][0].fee_msat, 0);
2876                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2877                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2878                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2879
2880                 assert_eq!(route.paths[0][1].pubkey, nodes[6]);
2881                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2882                 assert_eq!(route.paths[0][1].fee_msat, 100);
2883                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2884                 assert_eq!(route.paths[0][1].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2885                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2886
2887                 last_hops[0].0[0].fees.base_msat = 1000;
2888
2889                 // Revert to via 6 as the fee on 8 goes up
2890                 let payee = Payee::from_node_id(nodes[6]).with_route_hints(last_hops);
2891                 let route = get_route(&our_id, &payee, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
2892                 assert_eq!(route.paths[0].len(), 4);
2893
2894                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2895                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2896                 assert_eq!(route.paths[0][0].fee_msat, 200); // fee increased as its % of value transferred across node
2897                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2898                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2899                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2900
2901                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2902                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2903                 assert_eq!(route.paths[0][1].fee_msat, 100);
2904                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (7 << 8) | 1);
2905                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2906                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2907
2908                 assert_eq!(route.paths[0][2].pubkey, nodes[5]);
2909                 assert_eq!(route.paths[0][2].short_channel_id, 7);
2910                 assert_eq!(route.paths[0][2].fee_msat, 0);
2911                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (10 << 8) | 1);
2912                 // If we have a peer in the node map, we'll use their features here since we don't have
2913                 // a way of figuring out their features from the invoice:
2914                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
2915                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(7));
2916
2917                 assert_eq!(route.paths[0][3].pubkey, nodes[6]);
2918                 assert_eq!(route.paths[0][3].short_channel_id, 10);
2919                 assert_eq!(route.paths[0][3].fee_msat, 100);
2920                 assert_eq!(route.paths[0][3].cltv_expiry_delta, 42);
2921                 assert_eq!(route.paths[0][3].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2922                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2923
2924                 // ...but still use 8 for larger payments as 6 has a variable feerate
2925                 let route = get_route(&our_id, &payee, &network_graph, None, 2000, 42, Arc::clone(&logger), &scorer).unwrap();
2926                 assert_eq!(route.paths[0].len(), 5);
2927
2928                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2929                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2930                 assert_eq!(route.paths[0][0].fee_msat, 3000);
2931                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2932                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2933                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2934
2935                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2936                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2937                 assert_eq!(route.paths[0][1].fee_msat, 0);
2938                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2939                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2940                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2941
2942                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2943                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2944                 assert_eq!(route.paths[0][2].fee_msat, 0);
2945                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2946                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2947                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2948
2949                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2950                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2951                 assert_eq!(route.paths[0][3].fee_msat, 1000);
2952                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2953                 // If we have a peer in the node map, we'll use their features here since we don't have
2954                 // a way of figuring out their features from the invoice:
2955                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2956                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2957
2958                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2959                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2960                 assert_eq!(route.paths[0][4].fee_msat, 2000);
2961                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2962                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2963                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2964         }
2965
2966         fn do_unannounced_path_test(last_hop_htlc_max: Option<u64>, last_hop_fee_prop: u32, outbound_capacity_msat: u64, route_val: u64) -> Result<Route, LightningError> {
2967                 let source_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 41).repeat(32)).unwrap()[..]).unwrap());
2968                 let middle_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 42).repeat(32)).unwrap()[..]).unwrap());
2969                 let target_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 43).repeat(32)).unwrap()[..]).unwrap());
2970
2971                 // If we specify a channel to a middle hop, that overrides our local channel view and that gets used
2972                 let last_hops = RouteHint(vec![RouteHintHop {
2973                         src_node_id: middle_node_id,
2974                         short_channel_id: 8,
2975                         fees: RoutingFees {
2976                                 base_msat: 1000,
2977                                 proportional_millionths: last_hop_fee_prop,
2978                         },
2979                         cltv_expiry_delta: (8 << 8) | 1,
2980                         htlc_minimum_msat: None,
2981                         htlc_maximum_msat: last_hop_htlc_max,
2982                 }]);
2983                 let payee = Payee::from_node_id(target_node_id).with_route_hints(vec![last_hops]);
2984                 let our_chans = vec![get_channel_details(Some(42), middle_node_id, InitFeatures::from_le_bytes(vec![0b11]), outbound_capacity_msat)];
2985                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2986                 get_route(&source_node_id, &payee, &NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash()), Some(&our_chans.iter().collect::<Vec<_>>()), route_val, 42, &test_utils::TestLogger::new(), &scorer)
2987         }
2988
2989         #[test]
2990         fn unannounced_path_test() {
2991                 // We should be able to send a payment to a destination without any help of a routing graph
2992                 // if we have a channel with a common counterparty that appears in the first and last hop
2993                 // hints.
2994                 let route = do_unannounced_path_test(None, 1, 2000000, 1000000).unwrap();
2995
2996                 let middle_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 42).repeat(32)).unwrap()[..]).unwrap());
2997                 let target_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 43).repeat(32)).unwrap()[..]).unwrap());
2998                 assert_eq!(route.paths[0].len(), 2);
2999
3000                 assert_eq!(route.paths[0][0].pubkey, middle_node_id);
3001                 assert_eq!(route.paths[0][0].short_channel_id, 42);
3002                 assert_eq!(route.paths[0][0].fee_msat, 1001);
3003                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
3004                 assert_eq!(route.paths[0][0].node_features.le_flags(), &[0b11]);
3005                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
3006
3007                 assert_eq!(route.paths[0][1].pubkey, target_node_id);
3008                 assert_eq!(route.paths[0][1].short_channel_id, 8);
3009                 assert_eq!(route.paths[0][1].fee_msat, 1000000);
3010                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
3011                 assert_eq!(route.paths[0][1].node_features.le_flags(), &[0; 0]); // We dont pass flags in from invoices yet
3012                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
3013         }
3014
3015         #[test]
3016         fn overflow_unannounced_path_test_liquidity_underflow() {
3017                 // Previously, when we had a last-hop hint connected directly to a first-hop channel, where
3018                 // the last-hop had a fee which overflowed a u64, we'd panic.
3019                 // This was due to us adding the first-hop from us unconditionally, causing us to think
3020                 // we'd built a path (as our node is in the "best candidate" set), when we had not.
3021                 // In this test, we previously hit a subtraction underflow due to having less available
3022                 // liquidity at the last hop than 0.
3023                 assert!(do_unannounced_path_test(Some(21_000_000_0000_0000_000), 0, 21_000_000_0000_0000_000, 21_000_000_0000_0000_000).is_err());
3024         }
3025
3026         #[test]
3027         fn overflow_unannounced_path_test_feerate_overflow() {
3028                 // This tests for the same case as above, except instead of hitting a subtraction
3029                 // underflow, we hit a case where the fee charged at a hop overflowed.
3030                 assert!(do_unannounced_path_test(Some(21_000_000_0000_0000_000), 50000, 21_000_000_0000_0000_000, 21_000_000_0000_0000_000).is_err());
3031         }
3032
3033         #[test]
3034         fn available_amount_while_routing_test() {
3035                 // Tests whether we choose the correct available channel amount while routing.
3036
3037                 let (secp_ctx, network_graph, mut net_graph_msg_handler, chain_monitor, logger) = build_graph();
3038                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3039                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
3040                 let payee = Payee::from_node_id(nodes[2]).with_features(InvoiceFeatures::known());
3041
3042                 // We will use a simple single-path route from
3043                 // our node to node2 via node0: channels {1, 3}.
3044
3045                 // First disable all other paths.
3046                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3047                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3048                         short_channel_id: 2,
3049                         timestamp: 2,
3050                         flags: 2,
3051                         cltv_expiry_delta: 0,
3052                         htlc_minimum_msat: 0,
3053                         htlc_maximum_msat: OptionalField::Present(100_000),
3054                         fee_base_msat: 0,
3055                         fee_proportional_millionths: 0,
3056                         excess_data: Vec::new()
3057                 });
3058                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3059                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3060                         short_channel_id: 12,
3061                         timestamp: 2,
3062                         flags: 2,
3063                         cltv_expiry_delta: 0,
3064                         htlc_minimum_msat: 0,
3065                         htlc_maximum_msat: OptionalField::Present(100_000),
3066                         fee_base_msat: 0,
3067                         fee_proportional_millionths: 0,
3068                         excess_data: Vec::new()
3069                 });
3070
3071                 // Make the first channel (#1) very permissive,
3072                 // and we will be testing all limits on the second channel.
3073                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3074                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3075                         short_channel_id: 1,
3076                         timestamp: 2,
3077                         flags: 0,
3078                         cltv_expiry_delta: 0,
3079                         htlc_minimum_msat: 0,
3080                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
3081                         fee_base_msat: 0,
3082                         fee_proportional_millionths: 0,
3083                         excess_data: Vec::new()
3084                 });
3085
3086                 // First, let's see if routing works if we have absolutely no idea about the available amount.
3087                 // In this case, it should be set to 250_000 sats.
3088                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3089                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3090                         short_channel_id: 3,
3091                         timestamp: 2,
3092                         flags: 0,
3093                         cltv_expiry_delta: 0,
3094                         htlc_minimum_msat: 0,
3095                         htlc_maximum_msat: OptionalField::Absent,
3096                         fee_base_msat: 0,
3097                         fee_proportional_millionths: 0,
3098                         excess_data: Vec::new()
3099                 });
3100
3101                 {
3102                         // Attempt to route more than available results in a failure.
3103                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3104                                         &our_id, &payee, &network_graph, None, 250_000_001, 42, Arc::clone(&logger), &scorer) {
3105                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3106                         } else { panic!(); }
3107                 }
3108
3109                 {
3110                         // Now, attempt to route an exact amount we have should be fine.
3111                         let route = get_route(&our_id, &payee, &network_graph, None, 250_000_000, 42, Arc::clone(&logger), &scorer).unwrap();
3112                         assert_eq!(route.paths.len(), 1);
3113                         let path = route.paths.last().unwrap();
3114                         assert_eq!(path.len(), 2);
3115                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3116                         assert_eq!(path.last().unwrap().fee_msat, 250_000_000);
3117                 }
3118
3119                 // Check that setting outbound_capacity_msat in first_hops limits the channels.
3120                 // Disable channel #1 and use another first hop.
3121                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3122                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3123                         short_channel_id: 1,
3124                         timestamp: 3,
3125                         flags: 2,
3126                         cltv_expiry_delta: 0,
3127                         htlc_minimum_msat: 0,
3128                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
3129                         fee_base_msat: 0,
3130                         fee_proportional_millionths: 0,
3131                         excess_data: Vec::new()
3132                 });
3133
3134                 // Now, limit the first_hop by the outbound_capacity_msat of 200_000 sats.
3135                 let our_chans = vec![get_channel_details(Some(42), nodes[0].clone(), InitFeatures::from_le_bytes(vec![0b11]), 200_000_000)];
3136
3137                 {
3138                         // Attempt to route more than available results in a failure.
3139                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3140                                         &our_id, &payee, &network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 200_000_001, 42, Arc::clone(&logger), &scorer) {
3141                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3142                         } else { panic!(); }
3143                 }
3144
3145                 {
3146                         // Now, attempt to route an exact amount we have should be fine.
3147                         let route = get_route(&our_id, &payee, &network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 200_000_000, 42, Arc::clone(&logger), &scorer).unwrap();
3148                         assert_eq!(route.paths.len(), 1);
3149                         let path = route.paths.last().unwrap();
3150                         assert_eq!(path.len(), 2);
3151                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3152                         assert_eq!(path.last().unwrap().fee_msat, 200_000_000);
3153                 }
3154
3155                 // Enable channel #1 back.
3156                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3157                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3158                         short_channel_id: 1,
3159                         timestamp: 4,
3160                         flags: 0,
3161                         cltv_expiry_delta: 0,
3162                         htlc_minimum_msat: 0,
3163                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
3164                         fee_base_msat: 0,
3165                         fee_proportional_millionths: 0,
3166                         excess_data: Vec::new()
3167                 });
3168
3169
3170                 // Now let's see if routing works if we know only htlc_maximum_msat.
3171                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3172                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3173                         short_channel_id: 3,
3174                         timestamp: 3,
3175                         flags: 0,
3176                         cltv_expiry_delta: 0,
3177                         htlc_minimum_msat: 0,
3178                         htlc_maximum_msat: OptionalField::Present(15_000),
3179                         fee_base_msat: 0,
3180                         fee_proportional_millionths: 0,
3181                         excess_data: Vec::new()
3182                 });
3183
3184                 {
3185                         // Attempt to route more than available results in a failure.
3186                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3187                                         &our_id, &payee, &network_graph, None, 15_001, 42, Arc::clone(&logger), &scorer) {
3188                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3189                         } else { panic!(); }
3190                 }
3191
3192                 {
3193                         // Now, attempt to route an exact amount we have should be fine.
3194                         let route = get_route(&our_id, &payee, &network_graph, None, 15_000, 42, Arc::clone(&logger), &scorer).unwrap();
3195                         assert_eq!(route.paths.len(), 1);
3196                         let path = route.paths.last().unwrap();
3197                         assert_eq!(path.len(), 2);
3198                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3199                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
3200                 }
3201
3202                 // Now let's see if routing works if we know only capacity from the UTXO.
3203
3204                 // We can't change UTXO capacity on the fly, so we'll disable
3205                 // the existing channel and add another one with the capacity we need.
3206                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3207                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3208                         short_channel_id: 3,
3209                         timestamp: 4,
3210                         flags: 2,
3211                         cltv_expiry_delta: 0,
3212                         htlc_minimum_msat: 0,
3213                         htlc_maximum_msat: OptionalField::Absent,
3214                         fee_base_msat: 0,
3215                         fee_proportional_millionths: 0,
3216                         excess_data: Vec::new()
3217                 });
3218
3219                 let good_script = Builder::new().push_opcode(opcodes::all::OP_PUSHNUM_2)
3220                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[0]).serialize())
3221                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[2]).serialize())
3222                 .push_opcode(opcodes::all::OP_PUSHNUM_2)
3223                 .push_opcode(opcodes::all::OP_CHECKMULTISIG).into_script().to_v0_p2wsh();
3224
3225                 *chain_monitor.utxo_ret.lock().unwrap() = Ok(TxOut { value: 15, script_pubkey: good_script.clone() });
3226                 net_graph_msg_handler.add_chain_access(Some(chain_monitor));
3227
3228                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 333);
3229                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3230                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3231                         short_channel_id: 333,
3232                         timestamp: 1,
3233                         flags: 0,
3234                         cltv_expiry_delta: (3 << 8) | 1,
3235                         htlc_minimum_msat: 0,
3236                         htlc_maximum_msat: OptionalField::Absent,
3237                         fee_base_msat: 0,
3238                         fee_proportional_millionths: 0,
3239                         excess_data: Vec::new()
3240                 });
3241                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3242                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3243                         short_channel_id: 333,
3244                         timestamp: 1,
3245                         flags: 1,
3246                         cltv_expiry_delta: (3 << 8) | 2,
3247                         htlc_minimum_msat: 0,
3248                         htlc_maximum_msat: OptionalField::Absent,
3249                         fee_base_msat: 100,
3250                         fee_proportional_millionths: 0,
3251                         excess_data: Vec::new()
3252                 });
3253
3254                 {
3255                         // Attempt to route more than available results in a failure.
3256                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3257                                         &our_id, &payee, &network_graph, None, 15_001, 42, Arc::clone(&logger), &scorer) {
3258                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3259                         } else { panic!(); }
3260                 }
3261
3262                 {
3263                         // Now, attempt to route an exact amount we have should be fine.
3264                         let route = get_route(&our_id, &payee, &network_graph, None, 15_000, 42, Arc::clone(&logger), &scorer).unwrap();
3265                         assert_eq!(route.paths.len(), 1);
3266                         let path = route.paths.last().unwrap();
3267                         assert_eq!(path.len(), 2);
3268                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3269                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
3270                 }
3271
3272                 // Now let's see if routing chooses htlc_maximum_msat over UTXO capacity.
3273                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3274                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3275                         short_channel_id: 333,
3276                         timestamp: 6,
3277                         flags: 0,
3278                         cltv_expiry_delta: 0,
3279                         htlc_minimum_msat: 0,
3280                         htlc_maximum_msat: OptionalField::Present(10_000),
3281                         fee_base_msat: 0,
3282                         fee_proportional_millionths: 0,
3283                         excess_data: Vec::new()
3284                 });
3285
3286                 {
3287                         // Attempt to route more than available results in a failure.
3288                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3289                                         &our_id, &payee, &network_graph, None, 10_001, 42, Arc::clone(&logger), &scorer) {
3290                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3291                         } else { panic!(); }
3292                 }
3293
3294                 {
3295                         // Now, attempt to route an exact amount we have should be fine.
3296                         let route = get_route(&our_id, &payee, &network_graph, None, 10_000, 42, Arc::clone(&logger), &scorer).unwrap();
3297                         assert_eq!(route.paths.len(), 1);
3298                         let path = route.paths.last().unwrap();
3299                         assert_eq!(path.len(), 2);
3300                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3301                         assert_eq!(path.last().unwrap().fee_msat, 10_000);
3302                 }
3303         }
3304
3305         #[test]
3306         fn available_liquidity_last_hop_test() {
3307                 // Check that available liquidity properly limits the path even when only
3308                 // one of the latter hops is limited.
3309                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
3310                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3311                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
3312                 let payee = Payee::from_node_id(nodes[3]).with_features(InvoiceFeatures::known());
3313
3314                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3315                 // {12, 13, 11} have the capacities of 100, {6} has a capacity of 50.
3316                 // Total capacity: 50 sats.
3317
3318                 // Disable other potential paths.
3319                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3320                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3321                         short_channel_id: 2,
3322                         timestamp: 2,
3323                         flags: 2,
3324                         cltv_expiry_delta: 0,
3325                         htlc_minimum_msat: 0,
3326                         htlc_maximum_msat: OptionalField::Present(100_000),
3327                         fee_base_msat: 0,
3328                         fee_proportional_millionths: 0,
3329                         excess_data: Vec::new()
3330                 });
3331                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3332                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3333                         short_channel_id: 7,
3334                         timestamp: 2,
3335                         flags: 2,
3336                         cltv_expiry_delta: 0,
3337                         htlc_minimum_msat: 0,
3338                         htlc_maximum_msat: OptionalField::Present(100_000),
3339                         fee_base_msat: 0,
3340                         fee_proportional_millionths: 0,
3341                         excess_data: Vec::new()
3342                 });
3343
3344                 // Limit capacities
3345
3346                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3347                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3348                         short_channel_id: 12,
3349                         timestamp: 2,
3350                         flags: 0,
3351                         cltv_expiry_delta: 0,
3352                         htlc_minimum_msat: 0,
3353                         htlc_maximum_msat: OptionalField::Present(100_000),
3354                         fee_base_msat: 0,
3355                         fee_proportional_millionths: 0,
3356                         excess_data: Vec::new()
3357                 });
3358                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3359                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3360                         short_channel_id: 13,
3361                         timestamp: 2,
3362                         flags: 0,
3363                         cltv_expiry_delta: 0,
3364                         htlc_minimum_msat: 0,
3365                         htlc_maximum_msat: OptionalField::Present(100_000),
3366                         fee_base_msat: 0,
3367                         fee_proportional_millionths: 0,
3368                         excess_data: Vec::new()
3369                 });
3370
3371                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3372                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3373                         short_channel_id: 6,
3374                         timestamp: 2,
3375                         flags: 0,
3376                         cltv_expiry_delta: 0,
3377                         htlc_minimum_msat: 0,
3378                         htlc_maximum_msat: OptionalField::Present(50_000),
3379                         fee_base_msat: 0,
3380                         fee_proportional_millionths: 0,
3381                         excess_data: Vec::new()
3382                 });
3383                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3384                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3385                         short_channel_id: 11,
3386                         timestamp: 2,
3387                         flags: 0,
3388                         cltv_expiry_delta: 0,
3389                         htlc_minimum_msat: 0,
3390                         htlc_maximum_msat: OptionalField::Present(100_000),
3391                         fee_base_msat: 0,
3392                         fee_proportional_millionths: 0,
3393                         excess_data: Vec::new()
3394                 });
3395                 {
3396                         // Attempt to route more than available results in a failure.
3397                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3398                                         &our_id, &payee, &network_graph, None, 60_000, 42, Arc::clone(&logger), &scorer) {
3399                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3400                         } else { panic!(); }
3401                 }
3402
3403                 {
3404                         // Now, attempt to route 49 sats (just a bit below the capacity).
3405                         let route = get_route(&our_id, &payee, &network_graph, None, 49_000, 42, Arc::clone(&logger), &scorer).unwrap();
3406                         assert_eq!(route.paths.len(), 1);
3407                         let mut total_amount_paid_msat = 0;
3408                         for path in &route.paths {
3409                                 assert_eq!(path.len(), 4);
3410                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3411                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3412                         }
3413                         assert_eq!(total_amount_paid_msat, 49_000);
3414                 }
3415
3416                 {
3417                         // Attempt to route an exact amount is also fine
3418                         let route = get_route(&our_id, &payee, &network_graph, None, 50_000, 42, Arc::clone(&logger), &scorer).unwrap();
3419                         assert_eq!(route.paths.len(), 1);
3420                         let mut total_amount_paid_msat = 0;
3421                         for path in &route.paths {
3422                                 assert_eq!(path.len(), 4);
3423                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3424                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3425                         }
3426                         assert_eq!(total_amount_paid_msat, 50_000);
3427                 }
3428         }
3429
3430         #[test]
3431         fn ignore_fee_first_hop_test() {
3432                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
3433                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3434                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
3435                 let payee = Payee::from_node_id(nodes[2]);
3436
3437                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
3438                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3439                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3440                         short_channel_id: 1,
3441                         timestamp: 2,
3442                         flags: 0,
3443                         cltv_expiry_delta: 0,
3444                         htlc_minimum_msat: 0,
3445                         htlc_maximum_msat: OptionalField::Present(100_000),
3446                         fee_base_msat: 1_000_000,
3447                         fee_proportional_millionths: 0,
3448                         excess_data: Vec::new()
3449                 });
3450                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3451                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3452                         short_channel_id: 3,
3453                         timestamp: 2,
3454                         flags: 0,
3455                         cltv_expiry_delta: 0,
3456                         htlc_minimum_msat: 0,
3457                         htlc_maximum_msat: OptionalField::Present(50_000),
3458                         fee_base_msat: 0,
3459                         fee_proportional_millionths: 0,
3460                         excess_data: Vec::new()
3461                 });
3462
3463                 {
3464                         let route = get_route(&our_id, &payee, &network_graph, None, 50_000, 42, Arc::clone(&logger), &scorer).unwrap();
3465                         assert_eq!(route.paths.len(), 1);
3466                         let mut total_amount_paid_msat = 0;
3467                         for path in &route.paths {
3468                                 assert_eq!(path.len(), 2);
3469                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3470                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3471                         }
3472                         assert_eq!(total_amount_paid_msat, 50_000);
3473                 }
3474         }
3475
3476         #[test]
3477         fn simple_mpp_route_test() {
3478                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
3479                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3480                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
3481                 let payee = Payee::from_node_id(nodes[2]).with_features(InvoiceFeatures::known());
3482
3483                 // We need a route consisting of 3 paths:
3484                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
3485                 // To achieve this, the amount being transferred should be around
3486                 // the total capacity of these 3 paths.
3487
3488                 // First, we set limits on these (previously unlimited) channels.
3489                 // Their aggregate capacity will be 50 + 60 + 180 = 290 sats.
3490
3491                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
3492                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3493                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3494                         short_channel_id: 1,
3495                         timestamp: 2,
3496                         flags: 0,
3497                         cltv_expiry_delta: 0,
3498                         htlc_minimum_msat: 0,
3499                         htlc_maximum_msat: OptionalField::Present(100_000),
3500                         fee_base_msat: 0,
3501                         fee_proportional_millionths: 0,
3502                         excess_data: Vec::new()
3503                 });
3504                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3505                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3506                         short_channel_id: 3,
3507                         timestamp: 2,
3508                         flags: 0,
3509                         cltv_expiry_delta: 0,
3510                         htlc_minimum_msat: 0,
3511                         htlc_maximum_msat: OptionalField::Present(50_000),
3512                         fee_base_msat: 0,
3513                         fee_proportional_millionths: 0,
3514                         excess_data: Vec::new()
3515                 });
3516
3517                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats
3518                 // (total limit 60).
3519                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3520                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3521                         short_channel_id: 12,
3522                         timestamp: 2,
3523                         flags: 0,
3524                         cltv_expiry_delta: 0,
3525                         htlc_minimum_msat: 0,
3526                         htlc_maximum_msat: OptionalField::Present(60_000),
3527                         fee_base_msat: 0,
3528                         fee_proportional_millionths: 0,
3529                         excess_data: Vec::new()
3530                 });
3531                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3532                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3533                         short_channel_id: 13,
3534                         timestamp: 2,
3535                         flags: 0,
3536                         cltv_expiry_delta: 0,
3537                         htlc_minimum_msat: 0,
3538                         htlc_maximum_msat: OptionalField::Present(60_000),
3539                         fee_base_msat: 0,
3540                         fee_proportional_millionths: 0,
3541                         excess_data: Vec::new()
3542                 });
3543
3544                 // Path via node1 is channels {2, 4}. Limit them to 200 and 180 sats
3545                 // (total capacity 180 sats).
3546                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3547                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3548                         short_channel_id: 2,
3549                         timestamp: 2,
3550                         flags: 0,
3551                         cltv_expiry_delta: 0,
3552                         htlc_minimum_msat: 0,
3553                         htlc_maximum_msat: OptionalField::Present(200_000),
3554                         fee_base_msat: 0,
3555                         fee_proportional_millionths: 0,
3556                         excess_data: Vec::new()
3557                 });
3558                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3559                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3560                         short_channel_id: 4,
3561                         timestamp: 2,
3562                         flags: 0,
3563                         cltv_expiry_delta: 0,
3564                         htlc_minimum_msat: 0,
3565                         htlc_maximum_msat: OptionalField::Present(180_000),
3566                         fee_base_msat: 0,
3567                         fee_proportional_millionths: 0,
3568                         excess_data: Vec::new()
3569                 });
3570
3571                 {
3572                         // Attempt to route more than available results in a failure.
3573                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3574                                         &our_id, &payee, &network_graph, None, 300_000, 42, Arc::clone(&logger), &scorer) {
3575                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3576                         } else { panic!(); }
3577                 }
3578
3579                 {
3580                         // Now, attempt to route 250 sats (just a bit below the capacity).
3581                         // Our algorithm should provide us with these 3 paths.
3582                         let route = get_route(&our_id, &payee, &network_graph, None, 250_000, 42, Arc::clone(&logger), &scorer).unwrap();
3583                         assert_eq!(route.paths.len(), 3);
3584                         let mut total_amount_paid_msat = 0;
3585                         for path in &route.paths {
3586                                 assert_eq!(path.len(), 2);
3587                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3588                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3589                         }
3590                         assert_eq!(total_amount_paid_msat, 250_000);
3591                 }
3592
3593                 {
3594                         // Attempt to route an exact amount is also fine
3595                         let route = get_route(&our_id, &payee, &network_graph, None, 290_000, 42, Arc::clone(&logger), &scorer).unwrap();
3596                         assert_eq!(route.paths.len(), 3);
3597                         let mut total_amount_paid_msat = 0;
3598                         for path in &route.paths {
3599                                 assert_eq!(path.len(), 2);
3600                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3601                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3602                         }
3603                         assert_eq!(total_amount_paid_msat, 290_000);
3604                 }
3605         }
3606
3607         #[test]
3608         fn long_mpp_route_test() {
3609                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
3610                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3611                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
3612                 let payee = Payee::from_node_id(nodes[3]).with_features(InvoiceFeatures::known());
3613
3614                 // We need a route consisting of 3 paths:
3615                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
3616                 // Note that these paths overlap (channels 5, 12, 13).
3617                 // We will route 300 sats.
3618                 // Each path will have 100 sats capacity, those channels which
3619                 // are used twice will have 200 sats capacity.
3620
3621                 // Disable other potential paths.
3622                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3623                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3624                         short_channel_id: 2,
3625                         timestamp: 2,
3626                         flags: 2,
3627                         cltv_expiry_delta: 0,
3628                         htlc_minimum_msat: 0,
3629                         htlc_maximum_msat: OptionalField::Present(100_000),
3630                         fee_base_msat: 0,
3631                         fee_proportional_millionths: 0,
3632                         excess_data: Vec::new()
3633                 });
3634                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3635                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3636                         short_channel_id: 7,
3637                         timestamp: 2,
3638                         flags: 2,
3639                         cltv_expiry_delta: 0,
3640                         htlc_minimum_msat: 0,
3641                         htlc_maximum_msat: OptionalField::Present(100_000),
3642                         fee_base_msat: 0,
3643                         fee_proportional_millionths: 0,
3644                         excess_data: Vec::new()
3645                 });
3646
3647                 // Path via {node0, node2} is channels {1, 3, 5}.
3648                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3649                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3650                         short_channel_id: 1,
3651                         timestamp: 2,
3652                         flags: 0,
3653                         cltv_expiry_delta: 0,
3654                         htlc_minimum_msat: 0,
3655                         htlc_maximum_msat: OptionalField::Present(100_000),
3656                         fee_base_msat: 0,
3657                         fee_proportional_millionths: 0,
3658                         excess_data: Vec::new()
3659                 });
3660                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3661                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3662                         short_channel_id: 3,
3663                         timestamp: 2,
3664                         flags: 0,
3665                         cltv_expiry_delta: 0,
3666                         htlc_minimum_msat: 0,
3667                         htlc_maximum_msat: OptionalField::Present(100_000),
3668                         fee_base_msat: 0,
3669                         fee_proportional_millionths: 0,
3670                         excess_data: Vec::new()
3671                 });
3672
3673                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3674                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3675                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3676                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3677                         short_channel_id: 5,
3678                         timestamp: 2,
3679                         flags: 0,
3680                         cltv_expiry_delta: 0,
3681                         htlc_minimum_msat: 0,
3682                         htlc_maximum_msat: OptionalField::Present(200_000),
3683                         fee_base_msat: 0,
3684                         fee_proportional_millionths: 0,
3685                         excess_data: Vec::new()
3686                 });
3687
3688                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3689                 // Add 100 sats to the capacities of {12, 13}, because these channels
3690                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3691                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3692                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3693                         short_channel_id: 12,
3694                         timestamp: 2,
3695                         flags: 0,
3696                         cltv_expiry_delta: 0,
3697                         htlc_minimum_msat: 0,
3698                         htlc_maximum_msat: OptionalField::Present(200_000),
3699                         fee_base_msat: 0,
3700                         fee_proportional_millionths: 0,
3701                         excess_data: Vec::new()
3702                 });
3703                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3704                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3705                         short_channel_id: 13,
3706                         timestamp: 2,
3707                         flags: 0,
3708                         cltv_expiry_delta: 0,
3709                         htlc_minimum_msat: 0,
3710                         htlc_maximum_msat: OptionalField::Present(200_000),
3711                         fee_base_msat: 0,
3712                         fee_proportional_millionths: 0,
3713                         excess_data: Vec::new()
3714                 });
3715
3716                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3717                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3718                         short_channel_id: 6,
3719                         timestamp: 2,
3720                         flags: 0,
3721                         cltv_expiry_delta: 0,
3722                         htlc_minimum_msat: 0,
3723                         htlc_maximum_msat: OptionalField::Present(100_000),
3724                         fee_base_msat: 0,
3725                         fee_proportional_millionths: 0,
3726                         excess_data: Vec::new()
3727                 });
3728                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3729                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3730                         short_channel_id: 11,
3731                         timestamp: 2,
3732                         flags: 0,
3733                         cltv_expiry_delta: 0,
3734                         htlc_minimum_msat: 0,
3735                         htlc_maximum_msat: OptionalField::Present(100_000),
3736                         fee_base_msat: 0,
3737                         fee_proportional_millionths: 0,
3738                         excess_data: Vec::new()
3739                 });
3740
3741                 // Path via {node7, node2} is channels {12, 13, 5}.
3742                 // We already limited them to 200 sats (they are used twice for 100 sats).
3743                 // Nothing to do here.
3744
3745                 {
3746                         // Attempt to route more than available results in a failure.
3747                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3748                                         &our_id, &payee, &network_graph, None, 350_000, 42, Arc::clone(&logger), &scorer) {
3749                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3750                         } else { panic!(); }
3751                 }
3752
3753                 {
3754                         // Now, attempt to route 300 sats (exact amount we can route).
3755                         // Our algorithm should provide us with these 3 paths, 100 sats each.
3756                         let route = get_route(&our_id, &payee, &network_graph, None, 300_000, 42, Arc::clone(&logger), &scorer).unwrap();
3757                         assert_eq!(route.paths.len(), 3);
3758
3759                         let mut total_amount_paid_msat = 0;
3760                         for path in &route.paths {
3761                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3762                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3763                         }
3764                         assert_eq!(total_amount_paid_msat, 300_000);
3765                 }
3766
3767         }
3768
3769         #[test]
3770         fn mpp_cheaper_route_test() {
3771                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
3772                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3773                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
3774                 let payee = Payee::from_node_id(nodes[3]).with_features(InvoiceFeatures::known());
3775
3776                 // This test checks that if we have two cheaper paths and one more expensive path,
3777                 // so that liquidity-wise any 2 of 3 combination is sufficient,
3778                 // two cheaper paths will be taken.
3779                 // These paths have equal available liquidity.
3780
3781                 // We need a combination of 3 paths:
3782                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
3783                 // Note that these paths overlap (channels 5, 12, 13).
3784                 // Each path will have 100 sats capacity, those channels which
3785                 // are used twice will have 200 sats capacity.
3786
3787                 // Disable other potential paths.
3788                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3789                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3790                         short_channel_id: 2,
3791                         timestamp: 2,
3792                         flags: 2,
3793                         cltv_expiry_delta: 0,
3794                         htlc_minimum_msat: 0,
3795                         htlc_maximum_msat: OptionalField::Present(100_000),
3796                         fee_base_msat: 0,
3797                         fee_proportional_millionths: 0,
3798                         excess_data: Vec::new()
3799                 });
3800                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3801                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3802                         short_channel_id: 7,
3803                         timestamp: 2,
3804                         flags: 2,
3805                         cltv_expiry_delta: 0,
3806                         htlc_minimum_msat: 0,
3807                         htlc_maximum_msat: OptionalField::Present(100_000),
3808                         fee_base_msat: 0,
3809                         fee_proportional_millionths: 0,
3810                         excess_data: Vec::new()
3811                 });
3812
3813                 // Path via {node0, node2} is channels {1, 3, 5}.
3814                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3815                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3816                         short_channel_id: 1,
3817                         timestamp: 2,
3818                         flags: 0,
3819                         cltv_expiry_delta: 0,
3820                         htlc_minimum_msat: 0,
3821                         htlc_maximum_msat: OptionalField::Present(100_000),
3822                         fee_base_msat: 0,
3823                         fee_proportional_millionths: 0,
3824                         excess_data: Vec::new()
3825                 });
3826                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3827                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3828                         short_channel_id: 3,
3829                         timestamp: 2,
3830                         flags: 0,
3831                         cltv_expiry_delta: 0,
3832                         htlc_minimum_msat: 0,
3833                         htlc_maximum_msat: OptionalField::Present(100_000),
3834                         fee_base_msat: 0,
3835                         fee_proportional_millionths: 0,
3836                         excess_data: Vec::new()
3837                 });
3838
3839                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3840                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3841                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3842                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3843                         short_channel_id: 5,
3844                         timestamp: 2,
3845                         flags: 0,
3846                         cltv_expiry_delta: 0,
3847                         htlc_minimum_msat: 0,
3848                         htlc_maximum_msat: OptionalField::Present(200_000),
3849                         fee_base_msat: 0,
3850                         fee_proportional_millionths: 0,
3851                         excess_data: Vec::new()
3852                 });
3853
3854                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3855                 // Add 100 sats to the capacities of {12, 13}, because these channels
3856                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3857                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3858                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3859                         short_channel_id: 12,
3860                         timestamp: 2,
3861                         flags: 0,
3862                         cltv_expiry_delta: 0,
3863                         htlc_minimum_msat: 0,
3864                         htlc_maximum_msat: OptionalField::Present(200_000),
3865                         fee_base_msat: 0,
3866                         fee_proportional_millionths: 0,
3867                         excess_data: Vec::new()
3868                 });
3869                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3870                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3871                         short_channel_id: 13,
3872                         timestamp: 2,
3873                         flags: 0,
3874                         cltv_expiry_delta: 0,
3875                         htlc_minimum_msat: 0,
3876                         htlc_maximum_msat: OptionalField::Present(200_000),
3877                         fee_base_msat: 0,
3878                         fee_proportional_millionths: 0,
3879                         excess_data: Vec::new()
3880                 });
3881
3882                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3883                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3884                         short_channel_id: 6,
3885                         timestamp: 2,
3886                         flags: 0,
3887                         cltv_expiry_delta: 0,
3888                         htlc_minimum_msat: 0,
3889                         htlc_maximum_msat: OptionalField::Present(100_000),
3890                         fee_base_msat: 1_000,
3891                         fee_proportional_millionths: 0,
3892                         excess_data: Vec::new()
3893                 });
3894                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3895                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3896                         short_channel_id: 11,
3897                         timestamp: 2,
3898                         flags: 0,
3899                         cltv_expiry_delta: 0,
3900                         htlc_minimum_msat: 0,
3901                         htlc_maximum_msat: OptionalField::Present(100_000),
3902                         fee_base_msat: 0,
3903                         fee_proportional_millionths: 0,
3904                         excess_data: Vec::new()
3905                 });
3906
3907                 // Path via {node7, node2} is channels {12, 13, 5}.
3908                 // We already limited them to 200 sats (they are used twice for 100 sats).
3909                 // Nothing to do here.
3910
3911                 {
3912                         // Now, attempt to route 180 sats.
3913                         // Our algorithm should provide us with these 2 paths.
3914                         let route = get_route(&our_id, &payee, &network_graph, None, 180_000, 42, Arc::clone(&logger), &scorer).unwrap();
3915                         assert_eq!(route.paths.len(), 2);
3916
3917                         let mut total_value_transferred_msat = 0;
3918                         let mut total_paid_msat = 0;
3919                         for path in &route.paths {
3920                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3921                                 total_value_transferred_msat += path.last().unwrap().fee_msat;
3922                                 for hop in path {
3923                                         total_paid_msat += hop.fee_msat;
3924                                 }
3925                         }
3926                         // If we paid fee, this would be higher.
3927                         assert_eq!(total_value_transferred_msat, 180_000);
3928                         let total_fees_paid = total_paid_msat - total_value_transferred_msat;
3929                         assert_eq!(total_fees_paid, 0);
3930                 }
3931         }
3932
3933         #[test]
3934         fn fees_on_mpp_route_test() {
3935                 // This test makes sure that MPP algorithm properly takes into account
3936                 // fees charged on the channels, by making the fees impactful:
3937                 // if the fee is not properly accounted for, the behavior is different.
3938                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
3939                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3940                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
3941                 let payee = Payee::from_node_id(nodes[3]).with_features(InvoiceFeatures::known());
3942
3943                 // We need a route consisting of 2 paths:
3944                 // From our node to node3 via {node0, node2} and {node7, node2, node4}.
3945                 // We will route 200 sats, Each path will have 100 sats capacity.
3946
3947                 // This test is not particularly stable: e.g.,
3948                 // there's a way to route via {node0, node2, node4}.
3949                 // It works while pathfinding is deterministic, but can be broken otherwise.
3950                 // It's fine to ignore this concern for now.
3951
3952                 // Disable other potential paths.
3953                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3954                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3955                         short_channel_id: 2,
3956                         timestamp: 2,
3957                         flags: 2,
3958                         cltv_expiry_delta: 0,
3959                         htlc_minimum_msat: 0,
3960                         htlc_maximum_msat: OptionalField::Present(100_000),
3961                         fee_base_msat: 0,
3962                         fee_proportional_millionths: 0,
3963                         excess_data: Vec::new()
3964                 });
3965
3966                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3967                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3968                         short_channel_id: 7,
3969                         timestamp: 2,
3970                         flags: 2,
3971                         cltv_expiry_delta: 0,
3972                         htlc_minimum_msat: 0,
3973                         htlc_maximum_msat: OptionalField::Present(100_000),
3974                         fee_base_msat: 0,
3975                         fee_proportional_millionths: 0,
3976                         excess_data: Vec::new()
3977                 });
3978
3979                 // Path via {node0, node2} is channels {1, 3, 5}.
3980                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3981                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3982                         short_channel_id: 1,
3983                         timestamp: 2,
3984                         flags: 0,
3985                         cltv_expiry_delta: 0,
3986                         htlc_minimum_msat: 0,
3987                         htlc_maximum_msat: OptionalField::Present(100_000),
3988                         fee_base_msat: 0,
3989                         fee_proportional_millionths: 0,
3990                         excess_data: Vec::new()
3991                 });
3992                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3993                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3994                         short_channel_id: 3,
3995                         timestamp: 2,
3996                         flags: 0,
3997                         cltv_expiry_delta: 0,
3998                         htlc_minimum_msat: 0,
3999                         htlc_maximum_msat: OptionalField::Present(100_000),
4000                         fee_base_msat: 0,
4001                         fee_proportional_millionths: 0,
4002                         excess_data: Vec::new()
4003                 });
4004
4005                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
4006                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
4007                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4008                         short_channel_id: 5,
4009                         timestamp: 2,
4010                         flags: 0,
4011                         cltv_expiry_delta: 0,
4012                         htlc_minimum_msat: 0,
4013                         htlc_maximum_msat: OptionalField::Present(100_000),
4014                         fee_base_msat: 0,
4015                         fee_proportional_millionths: 0,
4016                         excess_data: Vec::new()
4017                 });
4018
4019                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
4020                 // All channels should be 100 sats capacity. But for the fee experiment,
4021                 // we'll add absolute fee of 150 sats paid for the use channel 6 (paid to node2 on channel 13).
4022                 // Since channel 12 allows to deliver only 250 sats to channel 13, channel 13 can transfer only
4023                 // 100 sats (and pay 150 sats in fees for the use of channel 6),
4024                 // so no matter how large are other channels,
4025                 // the whole path will be limited by 100 sats with just these 2 conditions:
4026                 // - channel 12 capacity is 250 sats
4027                 // - fee for channel 6 is 150 sats
4028                 // Let's test this by enforcing these 2 conditions and removing other limits.
4029                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4030                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4031                         short_channel_id: 12,
4032                         timestamp: 2,
4033                         flags: 0,
4034                         cltv_expiry_delta: 0,
4035                         htlc_minimum_msat: 0,
4036                         htlc_maximum_msat: OptionalField::Present(250_000),
4037                         fee_base_msat: 0,
4038                         fee_proportional_millionths: 0,
4039                         excess_data: Vec::new()
4040                 });
4041                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
4042                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4043                         short_channel_id: 13,
4044                         timestamp: 2,
4045                         flags: 0,
4046                         cltv_expiry_delta: 0,
4047                         htlc_minimum_msat: 0,
4048                         htlc_maximum_msat: OptionalField::Absent,
4049                         fee_base_msat: 0,
4050                         fee_proportional_millionths: 0,
4051                         excess_data: Vec::new()
4052                 });
4053
4054                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
4055                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4056                         short_channel_id: 6,
4057                         timestamp: 2,
4058                         flags: 0,
4059                         cltv_expiry_delta: 0,
4060                         htlc_minimum_msat: 0,
4061                         htlc_maximum_msat: OptionalField::Absent,
4062                         fee_base_msat: 150_000,
4063                         fee_proportional_millionths: 0,
4064                         excess_data: Vec::new()
4065                 });
4066                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
4067                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4068                         short_channel_id: 11,
4069                         timestamp: 2,
4070                         flags: 0,
4071                         cltv_expiry_delta: 0,
4072                         htlc_minimum_msat: 0,
4073                         htlc_maximum_msat: OptionalField::Absent,
4074                         fee_base_msat: 0,
4075                         fee_proportional_millionths: 0,
4076                         excess_data: Vec::new()
4077                 });
4078
4079                 {
4080                         // Attempt to route more than available results in a failure.
4081                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
4082                                         &our_id, &payee, &network_graph, None, 210_000, 42, Arc::clone(&logger), &scorer) {
4083                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
4084                         } else { panic!(); }
4085                 }
4086
4087                 {
4088                         // Now, attempt to route 200 sats (exact amount we can route).
4089                         let route = get_route(&our_id, &payee, &network_graph, None, 200_000, 42, Arc::clone(&logger), &scorer).unwrap();
4090                         assert_eq!(route.paths.len(), 2);
4091
4092                         let mut total_amount_paid_msat = 0;
4093                         for path in &route.paths {
4094                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
4095                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
4096                         }
4097                         assert_eq!(total_amount_paid_msat, 200_000);
4098                         assert_eq!(route.get_total_fees(), 150_000);
4099                 }
4100         }
4101
4102         #[test]
4103         fn mpp_with_last_hops() {
4104                 // Previously, if we tried to send an MPP payment to a destination which was only reachable
4105                 // via a single last-hop route hint, we'd fail to route if we first collected routes
4106                 // totaling close but not quite enough to fund the full payment.
4107                 //
4108                 // This was because we considered last-hop hints to have exactly the sought payment amount
4109                 // instead of the amount we were trying to collect, needlessly limiting our path searching
4110                 // at the very first hop.
4111                 //
4112                 // Specifically, this interacted with our "all paths must fund at least 5% of total target"
4113                 // criterion to cause us to refuse all routes at the last hop hint which would be considered
4114                 // to only have the remaining to-collect amount in available liquidity.
4115                 //
4116                 // This bug appeared in production in some specific channel configurations.
4117                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
4118                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
4119                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4120                 let payee = Payee::from_node_id(PublicKey::from_slice(&[02; 33]).unwrap()).with_features(InvoiceFeatures::known())
4121                         .with_route_hints(vec![RouteHint(vec![RouteHintHop {
4122                                 src_node_id: nodes[2],
4123                                 short_channel_id: 42,
4124                                 fees: RoutingFees { base_msat: 0, proportional_millionths: 0 },
4125                                 cltv_expiry_delta: 42,
4126                                 htlc_minimum_msat: None,
4127                                 htlc_maximum_msat: None,
4128                         }])]);
4129
4130                 // Keep only two paths from us to nodes[2], both with a 99sat HTLC maximum, with one with
4131                 // no fee and one with a 1msat fee. Previously, trying to route 100 sats to nodes[2] here
4132                 // would first use the no-fee route and then fail to find a path along the second route as
4133                 // we think we can only send up to 1 additional sat over the last-hop but refuse to as its
4134                 // under 5% of our payment amount.
4135                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4136                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4137                         short_channel_id: 1,
4138                         timestamp: 2,
4139                         flags: 0,
4140                         cltv_expiry_delta: u16::max_value(),
4141                         htlc_minimum_msat: 0,
4142                         htlc_maximum_msat: OptionalField::Present(99_000),
4143                         fee_base_msat: u32::max_value(),
4144                         fee_proportional_millionths: u32::max_value(),
4145                         excess_data: Vec::new()
4146                 });
4147                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4148                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4149                         short_channel_id: 2,
4150                         timestamp: 2,
4151                         flags: 0,
4152                         cltv_expiry_delta: u16::max_value(),
4153                         htlc_minimum_msat: 0,
4154                         htlc_maximum_msat: OptionalField::Present(99_000),
4155                         fee_base_msat: u32::max_value(),
4156                         fee_proportional_millionths: u32::max_value(),
4157                         excess_data: Vec::new()
4158                 });
4159                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
4160                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4161                         short_channel_id: 4,
4162                         timestamp: 2,
4163                         flags: 0,
4164                         cltv_expiry_delta: (4 << 8) | 1,
4165                         htlc_minimum_msat: 0,
4166                         htlc_maximum_msat: OptionalField::Absent,
4167                         fee_base_msat: 1,
4168                         fee_proportional_millionths: 0,
4169                         excess_data: Vec::new()
4170                 });
4171                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
4172                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4173                         short_channel_id: 13,
4174                         timestamp: 2,
4175                         flags: 0|2, // Channel disabled
4176                         cltv_expiry_delta: (13 << 8) | 1,
4177                         htlc_minimum_msat: 0,
4178                         htlc_maximum_msat: OptionalField::Absent,
4179                         fee_base_msat: 0,
4180                         fee_proportional_millionths: 2000000,
4181                         excess_data: Vec::new()
4182                 });
4183
4184                 // Get a route for 100 sats and check that we found the MPP route no problem and didn't
4185                 // overpay at all.
4186                 let route = get_route(&our_id, &payee, &network_graph, None, 100_000, 42, Arc::clone(&logger), &scorer).unwrap();
4187                 assert_eq!(route.paths.len(), 2);
4188                 // Paths are somewhat randomly ordered, but:
4189                 // * the first is channel 2 (1 msat fee) -> channel 4 -> channel 42
4190                 // * the second is channel 1 (0 fee, but 99 sat maximum) -> channel 3 -> channel 42
4191                 assert_eq!(route.paths[0][0].short_channel_id, 2);
4192                 assert_eq!(route.paths[0][0].fee_msat, 1);
4193                 assert_eq!(route.paths[0][2].fee_msat, 1_000);
4194                 assert_eq!(route.paths[1][0].short_channel_id, 1);
4195                 assert_eq!(route.paths[1][0].fee_msat, 0);
4196                 assert_eq!(route.paths[1][2].fee_msat, 99_000);
4197                 assert_eq!(route.get_total_fees(), 1);
4198                 assert_eq!(route.get_total_amount(), 100_000);
4199         }
4200
4201         #[test]
4202         fn drop_lowest_channel_mpp_route_test() {
4203                 // This test checks that low-capacity channel is dropped when after
4204                 // path finding we realize that we found more capacity than we need.
4205                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
4206                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
4207                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4208                 let payee = Payee::from_node_id(nodes[2]).with_features(InvoiceFeatures::known());
4209
4210                 // We need a route consisting of 3 paths:
4211                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
4212
4213                 // The first and the second paths should be sufficient, but the third should be
4214                 // cheaper, so that we select it but drop later.
4215
4216                 // First, we set limits on these (previously unlimited) channels.
4217                 // Their aggregate capacity will be 50 + 60 + 20 = 130 sats.
4218
4219                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50);
4220                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4221                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4222                         short_channel_id: 1,
4223                         timestamp: 2,
4224                         flags: 0,
4225                         cltv_expiry_delta: 0,
4226                         htlc_minimum_msat: 0,
4227                         htlc_maximum_msat: OptionalField::Present(100_000),
4228                         fee_base_msat: 0,
4229                         fee_proportional_millionths: 0,
4230                         excess_data: Vec::new()
4231                 });
4232                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
4233                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4234                         short_channel_id: 3,
4235                         timestamp: 2,
4236                         flags: 0,
4237                         cltv_expiry_delta: 0,
4238                         htlc_minimum_msat: 0,
4239                         htlc_maximum_msat: OptionalField::Present(50_000),
4240                         fee_base_msat: 100,
4241                         fee_proportional_millionths: 0,
4242                         excess_data: Vec::new()
4243                 });
4244
4245                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats (total limit 60);
4246                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4247                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4248                         short_channel_id: 12,
4249                         timestamp: 2,
4250                         flags: 0,
4251                         cltv_expiry_delta: 0,
4252                         htlc_minimum_msat: 0,
4253                         htlc_maximum_msat: OptionalField::Present(60_000),
4254                         fee_base_msat: 100,
4255                         fee_proportional_millionths: 0,
4256                         excess_data: Vec::new()
4257                 });
4258                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
4259                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4260                         short_channel_id: 13,
4261                         timestamp: 2,
4262                         flags: 0,
4263                         cltv_expiry_delta: 0,
4264                         htlc_minimum_msat: 0,
4265                         htlc_maximum_msat: OptionalField::Present(60_000),
4266                         fee_base_msat: 0,
4267                         fee_proportional_millionths: 0,
4268                         excess_data: Vec::new()
4269                 });
4270
4271                 // Path via node1 is channels {2, 4}. Limit them to 20 and 20 sats (total capacity 20 sats).
4272                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4273                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4274                         short_channel_id: 2,
4275                         timestamp: 2,
4276                         flags: 0,
4277                         cltv_expiry_delta: 0,
4278                         htlc_minimum_msat: 0,
4279                         htlc_maximum_msat: OptionalField::Present(20_000),
4280                         fee_base_msat: 0,
4281                         fee_proportional_millionths: 0,
4282                         excess_data: Vec::new()
4283                 });
4284                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
4285                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4286                         short_channel_id: 4,
4287                         timestamp: 2,
4288                         flags: 0,
4289                         cltv_expiry_delta: 0,
4290                         htlc_minimum_msat: 0,
4291                         htlc_maximum_msat: OptionalField::Present(20_000),
4292                         fee_base_msat: 0,
4293                         fee_proportional_millionths: 0,
4294                         excess_data: Vec::new()
4295                 });
4296
4297                 {
4298                         // Attempt to route more than available results in a failure.
4299                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
4300                                         &our_id, &payee, &network_graph, None, 150_000, 42, Arc::clone(&logger), &scorer) {
4301                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
4302                         } else { panic!(); }
4303                 }
4304
4305                 {
4306                         // Now, attempt to route 125 sats (just a bit below the capacity of 3 channels).
4307                         // Our algorithm should provide us with these 3 paths.
4308                         let route = get_route(&our_id, &payee, &network_graph, None, 125_000, 42, Arc::clone(&logger), &scorer).unwrap();
4309                         assert_eq!(route.paths.len(), 3);
4310                         let mut total_amount_paid_msat = 0;
4311                         for path in &route.paths {
4312                                 assert_eq!(path.len(), 2);
4313                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
4314                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
4315                         }
4316                         assert_eq!(total_amount_paid_msat, 125_000);
4317                 }
4318
4319                 {
4320                         // Attempt to route without the last small cheap channel
4321                         let route = get_route(&our_id, &payee, &network_graph, None, 90_000, 42, Arc::clone(&logger), &scorer).unwrap();
4322                         assert_eq!(route.paths.len(), 2);
4323                         let mut total_amount_paid_msat = 0;
4324                         for path in &route.paths {
4325                                 assert_eq!(path.len(), 2);
4326                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
4327                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
4328                         }
4329                         assert_eq!(total_amount_paid_msat, 90_000);
4330                 }
4331         }
4332
4333         #[test]
4334         fn min_criteria_consistency() {
4335                 // Test that we don't use an inconsistent metric between updating and walking nodes during
4336                 // our Dijkstra's pass. In the initial version of MPP, the "best source" for a given node
4337                 // was updated with a different criterion from the heap sorting, resulting in loops in
4338                 // calculated paths. We test for that specific case here.
4339
4340                 // We construct a network that looks like this:
4341                 //
4342                 //            node2 -1(3)2- node3
4343                 //              2          2
4344                 //               (2)     (4)
4345                 //                  1   1
4346                 //    node1 -1(5)2- node4 -1(1)2- node6
4347                 //    2
4348                 //   (6)
4349                 //        1
4350                 // our_node
4351                 //
4352                 // We create a loop on the side of our real path - our destination is node 6, with a
4353                 // previous hop of node 4. From 4, the cheapest previous path is channel 2 from node 2,
4354                 // followed by node 3 over channel 3. Thereafter, the cheapest next-hop is back to node 4
4355                 // (this time over channel 4). Channel 4 has 0 htlc_minimum_msat whereas channel 1 (the
4356                 // other channel with a previous-hop of node 4) has a high (but irrelevant to the overall
4357                 // payment) htlc_minimum_msat. In the original algorithm, this resulted in node4's
4358                 // "previous hop" being set to node 3, creating a loop in the path.
4359                 let secp_ctx = Secp256k1::new();
4360                 let logger = Arc::new(test_utils::TestLogger::new());
4361                 let network_graph = Arc::new(NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash()));
4362                 let net_graph_msg_handler = NetGraphMsgHandler::new(Arc::clone(&network_graph), None, Arc::clone(&logger));
4363                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
4364                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4365                 let payee = Payee::from_node_id(nodes[6]);
4366
4367                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
4368                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4369                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4370                         short_channel_id: 6,
4371                         timestamp: 1,
4372                         flags: 0,
4373                         cltv_expiry_delta: (6 << 8) | 0,
4374                         htlc_minimum_msat: 0,
4375                         htlc_maximum_msat: OptionalField::Absent,
4376                         fee_base_msat: 0,
4377                         fee_proportional_millionths: 0,
4378                         excess_data: Vec::new()
4379                 });
4380                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
4381
4382                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
4383                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
4384                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4385                         short_channel_id: 5,
4386                         timestamp: 1,
4387                         flags: 0,
4388                         cltv_expiry_delta: (5 << 8) | 0,
4389                         htlc_minimum_msat: 0,
4390                         htlc_maximum_msat: OptionalField::Absent,
4391                         fee_base_msat: 100,
4392                         fee_proportional_millionths: 0,
4393                         excess_data: Vec::new()
4394                 });
4395                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
4396
4397                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
4398                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
4399                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4400                         short_channel_id: 4,
4401                         timestamp: 1,
4402                         flags: 0,
4403                         cltv_expiry_delta: (4 << 8) | 0,
4404                         htlc_minimum_msat: 0,
4405                         htlc_maximum_msat: OptionalField::Absent,
4406                         fee_base_msat: 0,
4407                         fee_proportional_millionths: 0,
4408                         excess_data: Vec::new()
4409                 });
4410                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
4411
4412                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
4413                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
4414                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4415                         short_channel_id: 3,
4416                         timestamp: 1,
4417                         flags: 0,
4418                         cltv_expiry_delta: (3 << 8) | 0,
4419                         htlc_minimum_msat: 0,
4420                         htlc_maximum_msat: OptionalField::Absent,
4421                         fee_base_msat: 0,
4422                         fee_proportional_millionths: 0,
4423                         excess_data: Vec::new()
4424                 });
4425                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
4426
4427                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
4428                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
4429                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4430                         short_channel_id: 2,
4431                         timestamp: 1,
4432                         flags: 0,
4433                         cltv_expiry_delta: (2 << 8) | 0,
4434                         htlc_minimum_msat: 0,
4435                         htlc_maximum_msat: OptionalField::Absent,
4436                         fee_base_msat: 0,
4437                         fee_proportional_millionths: 0,
4438                         excess_data: Vec::new()
4439                 });
4440
4441                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[6], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
4442                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
4443                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4444                         short_channel_id: 1,
4445                         timestamp: 1,
4446                         flags: 0,
4447                         cltv_expiry_delta: (1 << 8) | 0,
4448                         htlc_minimum_msat: 100,
4449                         htlc_maximum_msat: OptionalField::Absent,
4450                         fee_base_msat: 0,
4451                         fee_proportional_millionths: 0,
4452                         excess_data: Vec::new()
4453                 });
4454                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[6], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
4455
4456                 {
4457                         // Now ensure the route flows simply over nodes 1 and 4 to 6.
4458                         let route = get_route(&our_id, &payee, &network_graph, None, 10_000, 42, Arc::clone(&logger), &scorer).unwrap();
4459                         assert_eq!(route.paths.len(), 1);
4460                         assert_eq!(route.paths[0].len(), 3);
4461
4462                         assert_eq!(route.paths[0][0].pubkey, nodes[1]);
4463                         assert_eq!(route.paths[0][0].short_channel_id, 6);
4464                         assert_eq!(route.paths[0][0].fee_msat, 100);
4465                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (5 << 8) | 0);
4466                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(1));
4467                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(6));
4468
4469                         assert_eq!(route.paths[0][1].pubkey, nodes[4]);
4470                         assert_eq!(route.paths[0][1].short_channel_id, 5);
4471                         assert_eq!(route.paths[0][1].fee_msat, 0);
4472                         assert_eq!(route.paths[0][1].cltv_expiry_delta, (1 << 8) | 0);
4473                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(4));
4474                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(5));
4475
4476                         assert_eq!(route.paths[0][2].pubkey, nodes[6]);
4477                         assert_eq!(route.paths[0][2].short_channel_id, 1);
4478                         assert_eq!(route.paths[0][2].fee_msat, 10_000);
4479                         assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
4480                         assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
4481                         assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(1));
4482                 }
4483         }
4484
4485
4486         #[test]
4487         fn exact_fee_liquidity_limit() {
4488                 // Test that if, while walking the graph, we find a hop that has exactly enough liquidity
4489                 // for us, including later hop fees, we take it. In the first version of our MPP algorithm
4490                 // we calculated fees on a higher value, resulting in us ignoring such paths.
4491                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
4492                 let (our_privkey, our_id, _, nodes) = get_nodes(&secp_ctx);
4493                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4494                 let payee = Payee::from_node_id(nodes[2]);
4495
4496                 // We modify the graph to set the htlc_maximum of channel 2 to below the value we wish to
4497                 // send.
4498                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4499                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4500                         short_channel_id: 2,
4501                         timestamp: 2,
4502                         flags: 0,
4503                         cltv_expiry_delta: 0,
4504                         htlc_minimum_msat: 0,
4505                         htlc_maximum_msat: OptionalField::Present(85_000),
4506                         fee_base_msat: 0,
4507                         fee_proportional_millionths: 0,
4508                         excess_data: Vec::new()
4509                 });
4510
4511                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4512                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4513                         short_channel_id: 12,
4514                         timestamp: 2,
4515                         flags: 0,
4516                         cltv_expiry_delta: (4 << 8) | 1,
4517                         htlc_minimum_msat: 0,
4518                         htlc_maximum_msat: OptionalField::Present(270_000),
4519                         fee_base_msat: 0,
4520                         fee_proportional_millionths: 1000000,
4521                         excess_data: Vec::new()
4522                 });
4523
4524                 {
4525                         // Now, attempt to route 90 sats, which is exactly 90 sats at the last hop, plus the
4526                         // 200% fee charged channel 13 in the 1-to-2 direction.
4527                         let route = get_route(&our_id, &payee, &network_graph, None, 90_000, 42, Arc::clone(&logger), &scorer).unwrap();
4528                         assert_eq!(route.paths.len(), 1);
4529                         assert_eq!(route.paths[0].len(), 2);
4530
4531                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
4532                         assert_eq!(route.paths[0][0].short_channel_id, 12);
4533                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
4534                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
4535                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
4536                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
4537
4538                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
4539                         assert_eq!(route.paths[0][1].short_channel_id, 13);
4540                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
4541                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
4542                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
4543                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
4544                 }
4545         }
4546
4547         #[test]
4548         fn htlc_max_reduction_below_min() {
4549                 // Test that if, while walking the graph, we reduce the value being sent to meet an
4550                 // htlc_maximum_msat, we don't end up undershooting a later htlc_minimum_msat. In the
4551                 // initial version of MPP we'd accept such routes but reject them while recalculating fees,
4552                 // resulting in us thinking there is no possible path, even if other paths exist.
4553                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
4554                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
4555                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4556                 let payee = Payee::from_node_id(nodes[2]).with_features(InvoiceFeatures::known());
4557
4558                 // We modify the graph to set the htlc_minimum of channel 2 and 4 as needed - channel 2
4559                 // gets an htlc_maximum_msat of 80_000 and channel 4 an htlc_minimum_msat of 90_000. We
4560                 // then try to send 90_000.
4561                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4562                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4563                         short_channel_id: 2,
4564                         timestamp: 2,
4565                         flags: 0,
4566                         cltv_expiry_delta: 0,
4567                         htlc_minimum_msat: 0,
4568                         htlc_maximum_msat: OptionalField::Present(80_000),
4569                         fee_base_msat: 0,
4570                         fee_proportional_millionths: 0,
4571                         excess_data: Vec::new()
4572                 });
4573                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
4574                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4575                         short_channel_id: 4,
4576                         timestamp: 2,
4577                         flags: 0,
4578                         cltv_expiry_delta: (4 << 8) | 1,
4579                         htlc_minimum_msat: 90_000,
4580                         htlc_maximum_msat: OptionalField::Absent,
4581                         fee_base_msat: 0,
4582                         fee_proportional_millionths: 0,
4583                         excess_data: Vec::new()
4584                 });
4585
4586                 {
4587                         // Now, attempt to route 90 sats, hitting the htlc_minimum on channel 4, but
4588                         // overshooting the htlc_maximum on channel 2. Thus, we should pick the (absurdly
4589                         // expensive) channels 12-13 path.
4590                         let route = get_route(&our_id, &payee, &network_graph, None, 90_000, 42, Arc::clone(&logger), &scorer).unwrap();
4591                         assert_eq!(route.paths.len(), 1);
4592                         assert_eq!(route.paths[0].len(), 2);
4593
4594                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
4595                         assert_eq!(route.paths[0][0].short_channel_id, 12);
4596                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
4597                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
4598                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
4599                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
4600
4601                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
4602                         assert_eq!(route.paths[0][1].short_channel_id, 13);
4603                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
4604                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
4605                         assert_eq!(route.paths[0][1].node_features.le_flags(), InvoiceFeatures::known().le_flags());
4606                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
4607                 }
4608         }
4609
4610         #[test]
4611         fn multiple_direct_first_hops() {
4612                 // Previously we'd only ever considered one first hop path per counterparty.
4613                 // However, as we don't restrict users to one channel per peer, we really need to support
4614                 // looking at all first hop paths.
4615                 // Here we test that we do not ignore all-but-the-last first hop paths per counterparty (as
4616                 // we used to do by overwriting the `first_hop_targets` hashmap entry) and that we can MPP
4617                 // route over multiple channels with the same first hop.
4618                 let secp_ctx = Secp256k1::new();
4619                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
4620                 let logger = Arc::new(test_utils::TestLogger::new());
4621                 let network_graph = NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash());
4622                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4623                 let payee = Payee::from_node_id(nodes[0]).with_features(InvoiceFeatures::known());
4624
4625                 {
4626                         let route = get_route(&our_id, &payee, &network_graph, Some(&[
4627                                 &get_channel_details(Some(3), nodes[0], InitFeatures::known(), 200_000),
4628                                 &get_channel_details(Some(2), nodes[0], InitFeatures::known(), 10_000),
4629                         ]), 100_000, 42, Arc::clone(&logger), &scorer).unwrap();
4630                         assert_eq!(route.paths.len(), 1);
4631                         assert_eq!(route.paths[0].len(), 1);
4632
4633                         assert_eq!(route.paths[0][0].pubkey, nodes[0]);
4634                         assert_eq!(route.paths[0][0].short_channel_id, 3);
4635                         assert_eq!(route.paths[0][0].fee_msat, 100_000);
4636                 }
4637                 {
4638                         let route = get_route(&our_id, &payee, &network_graph, Some(&[
4639                                 &get_channel_details(Some(3), nodes[0], InitFeatures::known(), 50_000),
4640                                 &get_channel_details(Some(2), nodes[0], InitFeatures::known(), 50_000),
4641                         ]), 100_000, 42, Arc::clone(&logger), &scorer).unwrap();
4642                         assert_eq!(route.paths.len(), 2);
4643                         assert_eq!(route.paths[0].len(), 1);
4644                         assert_eq!(route.paths[1].len(), 1);
4645
4646                         assert_eq!(route.paths[0][0].pubkey, nodes[0]);
4647                         assert_eq!(route.paths[0][0].short_channel_id, 3);
4648                         assert_eq!(route.paths[0][0].fee_msat, 50_000);
4649
4650                         assert_eq!(route.paths[1][0].pubkey, nodes[0]);
4651                         assert_eq!(route.paths[1][0].short_channel_id, 2);
4652                         assert_eq!(route.paths[1][0].fee_msat, 50_000);
4653                 }
4654         }
4655
4656         #[test]
4657         fn prefers_shorter_route_with_higher_fees() {
4658                 let (secp_ctx, network_graph, _, _, logger) = build_graph();
4659                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
4660                 let payee = Payee::from_node_id(nodes[6]).with_route_hints(last_hops(&nodes));
4661
4662                 // Without penalizing each hop 100 msats, a longer path with lower fees is chosen.
4663                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4664                 let route = get_route(
4665                         &our_id, &payee, &network_graph, None, 100, 42,
4666                         Arc::clone(&logger), &scorer
4667                 ).unwrap();
4668                 let path = route.paths[0].iter().map(|hop| hop.short_channel_id).collect::<Vec<_>>();
4669
4670                 assert_eq!(route.get_total_fees(), 100);
4671                 assert_eq!(route.get_total_amount(), 100);
4672                 assert_eq!(path, vec![2, 4, 6, 11, 8]);
4673
4674                 // Applying a 100 msat penalty to each hop results in taking channels 7 and 10 to nodes[6]
4675                 // from nodes[2] rather than channel 6, 11, and 8, even though the longer path is cheaper.
4676                 let scorer = test_utils::TestScorer::with_fixed_penalty(100);
4677                 let route = get_route(
4678                         &our_id, &payee, &network_graph, None, 100, 42,
4679                         Arc::clone(&logger), &scorer
4680                 ).unwrap();
4681                 let path = route.paths[0].iter().map(|hop| hop.short_channel_id).collect::<Vec<_>>();
4682
4683                 assert_eq!(route.get_total_fees(), 300);
4684                 assert_eq!(route.get_total_amount(), 100);
4685                 assert_eq!(path, vec![2, 4, 7, 10]);
4686         }
4687
4688         struct BadChannelScorer {
4689                 short_channel_id: u64,
4690         }
4691
4692         #[cfg(c_bindings)]
4693         impl Writeable for BadChannelScorer {
4694                 fn write<W: Writer>(&self, _w: &mut W) -> Result<(), ::io::Error> { unimplemented!() }
4695         }
4696         impl Score for BadChannelScorer {
4697                 fn channel_penalty_msat(&self, short_channel_id: u64, _send_amt: u64, _capacity_msat: u64, _source: &NodeId, _target: &NodeId) -> u64 {
4698                         if short_channel_id == self.short_channel_id { u64::max_value() } else { 0 }
4699                 }
4700
4701                 fn payment_path_failed(&mut self, _path: &[&RouteHop], _short_channel_id: u64) {}
4702                 fn payment_path_successful(&mut self, _path: &[&RouteHop]) {}
4703         }
4704
4705         struct BadNodeScorer {
4706                 node_id: NodeId,
4707         }
4708
4709         #[cfg(c_bindings)]
4710         impl Writeable for BadNodeScorer {
4711                 fn write<W: Writer>(&self, _w: &mut W) -> Result<(), ::io::Error> { unimplemented!() }
4712         }
4713
4714         impl Score for BadNodeScorer {
4715                 fn channel_penalty_msat(&self, _short_channel_id: u64, _send_amt: u64, _capacity_msat: u64, _source: &NodeId, target: &NodeId) -> u64 {
4716                         if *target == self.node_id { u64::max_value() } else { 0 }
4717                 }
4718
4719                 fn payment_path_failed(&mut self, _path: &[&RouteHop], _short_channel_id: u64) {}
4720                 fn payment_path_successful(&mut self, _path: &[&RouteHop]) {}
4721         }
4722
4723         #[test]
4724         fn avoids_routing_through_bad_channels_and_nodes() {
4725                 let (secp_ctx, network_graph, _, _, logger) = build_graph();
4726                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
4727                 let payee = Payee::from_node_id(nodes[6]).with_route_hints(last_hops(&nodes));
4728
4729                 // A path to nodes[6] exists when no penalties are applied to any channel.
4730                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4731                 let route = get_route(
4732                         &our_id, &payee, &network_graph, None, 100, 42,
4733                         Arc::clone(&logger), &scorer
4734                 ).unwrap();
4735                 let path = route.paths[0].iter().map(|hop| hop.short_channel_id).collect::<Vec<_>>();
4736
4737                 assert_eq!(route.get_total_fees(), 100);
4738                 assert_eq!(route.get_total_amount(), 100);
4739                 assert_eq!(path, vec![2, 4, 6, 11, 8]);
4740
4741                 // A different path to nodes[6] exists if channel 6 cannot be routed over.
4742                 let scorer = BadChannelScorer { short_channel_id: 6 };
4743                 let route = get_route(
4744                         &our_id, &payee, &network_graph, None, 100, 42,
4745                         Arc::clone(&logger), &scorer
4746                 ).unwrap();
4747                 let path = route.paths[0].iter().map(|hop| hop.short_channel_id).collect::<Vec<_>>();
4748
4749                 assert_eq!(route.get_total_fees(), 300);
4750                 assert_eq!(route.get_total_amount(), 100);
4751                 assert_eq!(path, vec![2, 4, 7, 10]);
4752
4753                 // A path to nodes[6] does not exist if nodes[2] cannot be routed through.
4754                 let scorer = BadNodeScorer { node_id: NodeId::from_pubkey(&nodes[2]) };
4755                 match get_route(
4756                         &our_id, &payee, &network_graph, None, 100, 42,
4757                         Arc::clone(&logger), &scorer
4758                 ) {
4759                         Err(LightningError { err, .. } ) => {
4760                                 assert_eq!(err, "Failed to find a path to the given destination");
4761                         },
4762                         Ok(_) => panic!("Expected error"),
4763                 }
4764         }
4765
4766         #[test]
4767         fn total_fees_single_path() {
4768                 let route = Route {
4769                         paths: vec![vec![
4770                                 RouteHop {
4771                                         pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
4772                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4773                                         short_channel_id: 0, fee_msat: 100, cltv_expiry_delta: 0
4774                                 },
4775                                 RouteHop {
4776                                         pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
4777                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4778                                         short_channel_id: 0, fee_msat: 150, cltv_expiry_delta: 0
4779                                 },
4780                                 RouteHop {
4781                                         pubkey: PublicKey::from_slice(&hex::decode("027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007").unwrap()[..]).unwrap(),
4782                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4783                                         short_channel_id: 0, fee_msat: 225, cltv_expiry_delta: 0
4784                                 },
4785                         ]],
4786                         payee: None,
4787                 };
4788
4789                 assert_eq!(route.get_total_fees(), 250);
4790                 assert_eq!(route.get_total_amount(), 225);
4791         }
4792
4793         #[test]
4794         fn total_fees_multi_path() {
4795                 let route = Route {
4796                         paths: vec![vec![
4797                                 RouteHop {
4798                                         pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
4799                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4800                                         short_channel_id: 0, fee_msat: 100, cltv_expiry_delta: 0
4801                                 },
4802                                 RouteHop {
4803                                         pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
4804                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4805                                         short_channel_id: 0, fee_msat: 150, cltv_expiry_delta: 0
4806                                 },
4807                         ],vec![
4808                                 RouteHop {
4809                                         pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
4810                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4811                                         short_channel_id: 0, fee_msat: 100, cltv_expiry_delta: 0
4812                                 },
4813                                 RouteHop {
4814                                         pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
4815                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4816                                         short_channel_id: 0, fee_msat: 150, cltv_expiry_delta: 0
4817                                 },
4818                         ]],
4819                         payee: None,
4820                 };
4821
4822                 assert_eq!(route.get_total_fees(), 200);
4823                 assert_eq!(route.get_total_amount(), 300);
4824         }
4825
4826         #[test]
4827         fn total_empty_route_no_panic() {
4828                 // In an earlier version of `Route::get_total_fees` and `Route::get_total_amount`, they
4829                 // would both panic if the route was completely empty. We test to ensure they return 0
4830                 // here, even though its somewhat nonsensical as a route.
4831                 let route = Route { paths: Vec::new(), payee: None };
4832
4833                 assert_eq!(route.get_total_fees(), 0);
4834                 assert_eq!(route.get_total_amount(), 0);
4835         }
4836
4837         #[cfg(not(feature = "no-std"))]
4838         pub(super) fn random_init_seed() -> u64 {
4839                 // Because the default HashMap in std pulls OS randomness, we can use it as a (bad) RNG.
4840                 use core::hash::{BuildHasher, Hasher};
4841                 let seed = std::collections::hash_map::RandomState::new().build_hasher().finish();
4842                 println!("Using seed of {}", seed);
4843                 seed
4844         }
4845         #[cfg(not(feature = "no-std"))]
4846         use util::ser::Readable;
4847
4848         #[test]
4849         #[cfg(not(feature = "no-std"))]
4850         fn generate_routes() {
4851                 let mut d = match super::test_utils::get_route_file() {
4852                         Ok(f) => f,
4853                         Err(e) => {
4854                                 eprintln!("{}", e);
4855                                 return;
4856                         },
4857                 };
4858                 let graph = NetworkGraph::read(&mut d).unwrap();
4859                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4860
4861                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
4862                 let mut seed = random_init_seed() as usize;
4863                 let nodes = graph.read_only().nodes().clone();
4864                 'load_endpoints: for _ in 0..10 {
4865                         loop {
4866                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4867                                 let src = &PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4868                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4869                                 let dst = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4870                                 let payee = Payee::from_node_id(dst);
4871                                 let amt = seed as u64 % 200_000_000;
4872                                 if get_route(src, &payee, &graph, None, amt, 42, &test_utils::TestLogger::new(), &scorer).is_ok() {
4873                                         continue 'load_endpoints;
4874                                 }
4875                         }
4876                 }
4877         }
4878
4879         #[test]
4880         #[cfg(not(feature = "no-std"))]
4881         fn generate_routes_mpp() {
4882                 let mut d = match super::test_utils::get_route_file() {
4883                         Ok(f) => f,
4884                         Err(e) => {
4885                                 eprintln!("{}", e);
4886                                 return;
4887                         },
4888                 };
4889                 let graph = NetworkGraph::read(&mut d).unwrap();
4890                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4891
4892                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
4893                 let mut seed = random_init_seed() as usize;
4894                 let nodes = graph.read_only().nodes().clone();
4895                 'load_endpoints: for _ in 0..10 {
4896                         loop {
4897                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4898                                 let src = &PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4899                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4900                                 let dst = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4901                                 let payee = Payee::from_node_id(dst).with_features(InvoiceFeatures::known());
4902                                 let amt = seed as u64 % 200_000_000;
4903                                 if get_route(src, &payee, &graph, None, amt, 42, &test_utils::TestLogger::new(), &scorer).is_ok() {
4904                                         continue 'load_endpoints;
4905                                 }
4906                         }
4907                 }
4908         }
4909 }
4910
4911 #[cfg(all(test, not(feature = "no-std")))]
4912 pub(crate) mod test_utils {
4913         use std::fs::File;
4914         /// Tries to open a network graph file, or panics with a URL to fetch it.
4915         pub(crate) fn get_route_file() -> Result<std::fs::File, &'static str> {
4916                 let res = File::open("net_graph-2021-05-31.bin") // By default we're run in RL/lightning
4917                         .or_else(|_| File::open("lightning/net_graph-2021-05-31.bin")) // We may be run manually in RL/
4918                         .or_else(|_| { // Fall back to guessing based on the binary location
4919                                 // path is likely something like .../rust-lightning/target/debug/deps/lightning-...
4920                                 let mut path = std::env::current_exe().unwrap();
4921                                 path.pop(); // lightning-...
4922                                 path.pop(); // deps
4923                                 path.pop(); // debug
4924                                 path.pop(); // target
4925                                 path.push("lightning");
4926                                 path.push("net_graph-2021-05-31.bin");
4927                                 eprintln!("{}", path.to_str().unwrap());
4928                                 File::open(path)
4929                         })
4930                 .map_err(|_| "Please fetch https://bitcoin.ninja/ldk-net_graph-v0.0.15-2021-05-31.bin and place it at lightning/net_graph-2021-05-31.bin");
4931                 #[cfg(require_route_graph_test)]
4932                 return Ok(res.unwrap());
4933                 #[cfg(not(require_route_graph_test))]
4934                 return res;
4935         }
4936 }
4937
4938 #[cfg(all(test, feature = "unstable", not(feature = "no-std")))]
4939 mod benches {
4940         use super::*;
4941         use routing::scoring::Scorer;
4942         use util::logger::{Logger, Record};
4943
4944         use test::Bencher;
4945
4946         struct DummyLogger {}
4947         impl Logger for DummyLogger {
4948                 fn log(&self, _record: &Record) {}
4949         }
4950
4951         #[bench]
4952         fn generate_routes(bench: &mut Bencher) {
4953                 let mut d = test_utils::get_route_file().unwrap();
4954                 let graph = NetworkGraph::read(&mut d).unwrap();
4955                 let nodes = graph.read_only().nodes().clone();
4956                 let scorer = Scorer::with_fixed_penalty(0);
4957
4958                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
4959                 let mut path_endpoints = Vec::new();
4960                 let mut seed: usize = 0xdeadbeef;
4961                 'load_endpoints: for _ in 0..100 {
4962                         loop {
4963                                 seed *= 0xdeadbeef;
4964                                 let src = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4965                                 seed *= 0xdeadbeef;
4966                                 let dst = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4967                                 let payee = Payee::from_node_id(dst);
4968                                 let amt = seed as u64 % 1_000_000;
4969                                 if get_route(&src, &payee, &graph, None, amt, 42, &DummyLogger{}, &scorer).is_ok() {
4970                                         path_endpoints.push((src, dst, amt));
4971                                         continue 'load_endpoints;
4972                                 }
4973                         }
4974                 }
4975
4976                 // ...then benchmark finding paths between the nodes we learned.
4977                 let mut idx = 0;
4978                 bench.iter(|| {
4979                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
4980                         let payee = Payee::from_node_id(dst);
4981                         assert!(get_route(&src, &payee, &graph, None, amt, 42, &DummyLogger{}, &scorer).is_ok());
4982                         idx += 1;
4983                 });
4984         }
4985
4986         #[bench]
4987         fn generate_mpp_routes(bench: &mut Bencher) {
4988                 let mut d = test_utils::get_route_file().unwrap();
4989                 let graph = NetworkGraph::read(&mut d).unwrap();
4990                 let nodes = graph.read_only().nodes().clone();
4991                 let scorer = Scorer::with_fixed_penalty(0);
4992
4993                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
4994                 let mut path_endpoints = Vec::new();
4995                 let mut seed: usize = 0xdeadbeef;
4996                 'load_endpoints: for _ in 0..100 {
4997                         loop {
4998                                 seed *= 0xdeadbeef;
4999                                 let src = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
5000                                 seed *= 0xdeadbeef;
5001                                 let dst = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
5002                                 let payee = Payee::from_node_id(dst).with_features(InvoiceFeatures::known());
5003                                 let amt = seed as u64 % 1_000_000;
5004                                 if get_route(&src, &payee, &graph, None, amt, 42, &DummyLogger{}, &scorer).is_ok() {
5005                                         path_endpoints.push((src, dst, amt));
5006                                         continue 'load_endpoints;
5007                                 }
5008                         }
5009                 }
5010
5011                 // ...then benchmark finding paths between the nodes we learned.
5012                 let mut idx = 0;
5013                 bench.iter(|| {
5014                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
5015                         let payee = Payee::from_node_id(dst).with_features(InvoiceFeatures::known());
5016                         assert!(get_route(&src, &payee, &graph, None, amt, 42, &DummyLogger{}, &scorer).is_ok());
5017                         idx += 1;
5018                 });
5019         }
5020 }