_ 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::{DirectedChannelInfoWithUpdate, 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 `payment_params` 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 payment_params: Option<PaymentParameters>,
  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.payment_params, 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 payment_params = None;
 145                 read_tlv_fields!(reader, {
 146                         (1, payment_params, option),
 147                 });
 148                 Ok(Route { paths, payment_params })
 149         }
 150 }
 151
 152 /// Parameters needed to find a [`Route`].
 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 parameters of the failed payment path.
 161         pub payment_params: PaymentParameters,
 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, payment_params, required),
 172         (2, final_value_msat, required),
 173         (4, final_cltv_expiry_delta, required),
 174 });
 175
 176 /// Maximum total CTLV difference we allow for a full payment path.
 177 pub const DEFAULT_MAX_TOTAL_CLTV_EXPIRY_DELTA: u32 = 1008;
 178
 179 /// The recipient of a payment.
 180 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
 181 pub struct PaymentParameters {
 182         /// The node id of the payee.
 183         pub payee_pubkey: PublicKey,
 184
 185         /// Features supported by the payee.
 186         ///
 187         /// May be set from the payee's invoice or via [`for_keysend`]. May be `None` if the invoice
 188         /// does not contain any features.
 189         ///
 190         /// [`for_keysend`]: Self::for_keysend
 191         pub features: Option<InvoiceFeatures>,
 192
 193         /// Hints for routing to the payee, containing channels connecting the payee to public nodes.
 194         pub route_hints: Vec<RouteHint>,
 195
 196         /// Expiration of a payment to the payee, in seconds relative to the UNIX epoch.
 197         pub expiry_time: Option<u64>,
 198
 199         /// The maximum total CLTV delta we accept for the route.
 200         pub max_total_cltv_expiry_delta: u32,
 201 }
 202
 203 impl_writeable_tlv_based!(PaymentParameters, {
 204         (0, payee_pubkey, required),
 205         (1, max_total_cltv_expiry_delta, (default_value, DEFAULT_MAX_TOTAL_CLTV_EXPIRY_DELTA)),
 206         (2, features, option),
 207         (4, route_hints, vec_type),
 208         (6, expiry_time, option),
 209 });
 210
 211 impl PaymentParameters {
 212         /// Creates a payee with the node id of the given `pubkey`.
 213         pub fn from_node_id(payee_pubkey: PublicKey) -> Self {
 214                 Self {
 215                         payee_pubkey,
 216                         features: None,
 217                         route_hints: vec![],
 218                         expiry_time: None,
 219                         max_total_cltv_expiry_delta: DEFAULT_MAX_TOTAL_CLTV_EXPIRY_DELTA,
 220                 }
 221         }
 222
 223         /// Creates a payee with the node id of the given `pubkey` to use for keysend payments.
 224         pub fn for_keysend(payee_pubkey: PublicKey) -> Self {
 225                 Self::from_node_id(payee_pubkey).with_features(InvoiceFeatures::for_keysend())
 226         }
 227
 228         /// Includes the payee's features.
 229         ///
 230         /// (C-not exported) since bindings don't support move semantics
 231         pub fn with_features(self, features: InvoiceFeatures) -> Self {
 232                 Self { features: Some(features), ..self }
 233         }
 234
 235         /// Includes hints for routing to the payee.
 236         ///
 237         /// (C-not exported) since bindings don't support move semantics
 238         pub fn with_route_hints(self, route_hints: Vec<RouteHint>) -> Self {
 239                 Self { route_hints, ..self }
 240         }
 241
 242         /// Includes a payment expiration in seconds relative to the UNIX epoch.
 243         ///
 244         /// (C-not exported) since bindings don't support move semantics
 245         pub fn with_expiry_time(self, expiry_time: u64) -> Self {
 246                 Self { expiry_time: Some(expiry_time), ..self }
 247         }
 248
 249         /// Includes a limit for the total CLTV expiry delta which is considered during routing
 250         ///
 251         /// (C-not exported) since bindings don't support move semantics
 252         pub fn with_max_total_cltv_expiry_delta(self, max_total_cltv_expiry_delta: u32) -> Self {
 253                 Self { max_total_cltv_expiry_delta, ..self }
 254         }
 255 }
 256
 257 /// A list of hops along a payment path terminating with a channel to the recipient.
 258 #[derive(Clone, Debug, Hash, Eq, PartialEq)]
 259 pub struct RouteHint(pub Vec<RouteHintHop>);
 260
 261
 262 impl Writeable for RouteHint {
 263         fn write<W: ::util::ser::Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 264                 (self.0.len() as u64).write(writer)?;
 265                 for hop in self.0.iter() {
 266                         hop.write(writer)?;
 267                 }
 268                 Ok(())
 269         }
 270 }
 271
 272 impl Readable for RouteHint {
 273         fn read<R: io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
 274                 let hop_count: u64 = Readable::read(reader)?;
 275                 let mut hops = Vec::with_capacity(cmp::min(hop_count, 16) as usize);
 276                 for _ in 0..hop_count {
 277                         hops.push(Readable::read(reader)?);
 278                 }
 279                 Ok(Self(hops))
 280         }
 281 }
 282
 283 /// A channel descriptor for a hop along a payment path.
 284 #[derive(Clone, Debug, Hash, Eq, PartialEq)]
 285 pub struct RouteHintHop {
 286         /// The node_id of the non-target end of the route
 287         pub src_node_id: PublicKey,
 288         /// The short_channel_id of this channel
 289         pub short_channel_id: u64,
 290         /// The fees which must be paid to use this channel
 291         pub fees: RoutingFees,
 292         /// The difference in CLTV values between this node and the next node.
 293         pub cltv_expiry_delta: u16,
 294         /// The minimum value, in msat, which must be relayed to the next hop.
 295         pub htlc_minimum_msat: Option<u64>,
 296         /// The maximum value in msat available for routing with a single HTLC.
 297         pub htlc_maximum_msat: Option<u64>,
 298 }
 299
 300 impl_writeable_tlv_based!(RouteHintHop, {
 301         (0, src_node_id, required),
 302         (1, htlc_minimum_msat, option),
 303         (2, short_channel_id, required),
 304         (3, htlc_maximum_msat, option),
 305         (4, fees, required),
 306         (6, cltv_expiry_delta, required),
 307 });
 308
 309 #[derive(Eq, PartialEq)]
 310 struct RouteGraphNode {
 311         node_id: NodeId,
 312         lowest_fee_to_peer_through_node: u64,
 313         lowest_fee_to_node: u64,
 314         total_cltv_delta: u32,
 315         // The maximum value a yet-to-be-constructed payment path might flow through this node.
 316         // This value is upper-bounded by us by:
 317         // - how much is needed for a path being constructed
 318         // - how much value can channels following this node (up to the destination) can contribute,
 319         //   considering their capacity and fees
 320         value_contribution_msat: u64,
 321         /// The effective htlc_minimum_msat at this hop. If a later hop on the path had a higher HTLC
 322         /// minimum, we use it, plus the fees required at each earlier hop to meet it.
 323         path_htlc_minimum_msat: u64,
 324         /// All penalties incurred from this hop on the way to the destination, as calculated using
 325         /// channel scoring.
 326         path_penalty_msat: u64,
 327 }
 328
 329 impl cmp::Ord for RouteGraphNode {
 330         fn cmp(&self, other: &RouteGraphNode) -> cmp::Ordering {
 331                 let other_score = cmp::max(other.lowest_fee_to_peer_through_node, other.path_htlc_minimum_msat)
 332                         .checked_add(other.path_penalty_msat)
 333                         .unwrap_or_else(|| u64::max_value());
 334                 let self_score = cmp::max(self.lowest_fee_to_peer_through_node, self.path_htlc_minimum_msat)
 335                         .checked_add(self.path_penalty_msat)
 336                         .unwrap_or_else(|| u64::max_value());
 337                 other_score.cmp(&self_score).then_with(|| other.node_id.cmp(&self.node_id))
 338         }
 339 }
 340
 341 impl cmp::PartialOrd for RouteGraphNode {
 342         fn partial_cmp(&self, other: &RouteGraphNode) -> Option<cmp::Ordering> {
 343                 Some(self.cmp(other))
 344         }
 345 }
 346
 347 /// A wrapper around the various hop representations.
 348 ///
 349 /// Used to construct a [`PathBuildingHop`] and to estimate [`EffectiveCapacity`].
 350 #[derive(Clone, Debug)]
 351 enum CandidateRouteHop<'a> {
 352         /// A hop from the payer to the next hop to the payee, where the outbound liquidity is known.
 353         FirstHop {
 354                 details: &'a ChannelDetails,
 355         },
 356         /// A hop found in the [`NetworkGraph`], where the channel capacity may or may not be known.
 357         PublicHop {
 358                 info: DirectedChannelInfoWithUpdate<'a, 'a>,
 359                 short_channel_id: u64,
 360         },
 361         /// A hop to the payee found in the payment invoice, though not necessarily a direct channel.
 362         PrivateHop {
 363                 hint: &'a RouteHintHop,
 364         }
 365 }
 366
 367 impl<'a> CandidateRouteHop<'a> {
 368         fn short_channel_id(&self) -> u64 {
 369                 match self {
 370                         CandidateRouteHop::FirstHop { details } => details.short_channel_id.unwrap(),
 371                         CandidateRouteHop::PublicHop { short_channel_id, .. } => *short_channel_id,
 372                         CandidateRouteHop::PrivateHop { hint } => hint.short_channel_id,
 373                 }
 374         }
 375
 376         fn features(&self) -> ChannelFeatures {
 377                 match self {
 378                         CandidateRouteHop::FirstHop { details } => details.counterparty.features.to_context(),
 379                         CandidateRouteHop::PublicHop { info, .. } => info.inner().channel().features.clone(),
 380                         CandidateRouteHop::PrivateHop { .. } => ChannelFeatures::empty(),
 381                 }
 382         }
 383
 384         fn cltv_expiry_delta(&self) -> u32 {
 385                 match self {
 386                         CandidateRouteHop::FirstHop { .. } => 0,
 387                         CandidateRouteHop::PublicHop { info, .. } => {
 388                                 info.inner().direction().unwrap().cltv_expiry_delta as u32
 389                         },
 390                         CandidateRouteHop::PrivateHop { hint } => hint.cltv_expiry_delta as u32,
 391                 }
 392         }
 393
 394         fn htlc_minimum_msat(&self) -> u64 {
 395                 match self {
 396                         CandidateRouteHop::FirstHop { .. } => 0,
 397                         CandidateRouteHop::PublicHop { info, .. } => {
 398                                 info.inner().direction().unwrap().htlc_minimum_msat
 399                         },
 400                         CandidateRouteHop::PrivateHop { hint } => hint.htlc_minimum_msat.unwrap_or(0),
 401                 }
 402         }
 403
 404         fn fees(&self) -> RoutingFees {
 405                 match self {
 406                         CandidateRouteHop::FirstHop { .. } => RoutingFees {
 407                                 base_msat: 0, proportional_millionths: 0,
 408                         },
 409                         CandidateRouteHop::PublicHop { info, .. } => info.inner().direction().unwrap().fees,
 410                         CandidateRouteHop::PrivateHop { hint } => hint.fees,
 411                 }
 412         }
 413
 414         fn effective_capacity(&self) -> EffectiveCapacity {
 415                 match self {
 416                         CandidateRouteHop::FirstHop { details } => EffectiveCapacity::ExactLiquidity {
 417                                 liquidity_msat: details.outbound_capacity_msat,
 418                         },
 419                         CandidateRouteHop::PublicHop { info, .. } => info.inner().effective_capacity(),
 420                         CandidateRouteHop::PrivateHop { .. } => EffectiveCapacity::Infinite,
 421                 }
 422         }
 423 }
 424
 425 /// It's useful to keep track of the hops associated with the fees required to use them,
 426 /// so that we can choose cheaper paths (as per Dijkstra's algorithm).
 427 /// Fee values should be updated only in the context of the whole path, see update_value_and_recompute_fees.
 428 /// These fee values are useful to choose hops as we traverse the graph "payee-to-payer".
 429 #[derive(Clone, Debug)]
 430 struct PathBuildingHop<'a> {
 431         // Note that this should be dropped in favor of loading it from CandidateRouteHop, but doing so
 432         // is a larger refactor and will require careful performance analysis.
 433         node_id: NodeId,
 434         candidate: CandidateRouteHop<'a>,
 435         fee_msat: u64,
 436
 437         /// Minimal fees required to route to the source node of the current hop via any of its inbound channels.
 438         src_lowest_inbound_fees: RoutingFees,
 439         /// All the fees paid *after* this channel on the way to the destination
 440         next_hops_fee_msat: u64,
 441         /// Fee paid for the use of the current channel (see candidate.fees()).
 442         /// The value will be actually deducted from the counterparty balance on the previous link.
 443         hop_use_fee_msat: u64,
 444         /// Used to compare channels when choosing the for routing.
 445         /// Includes paying for the use of a hop and the following hops, as well as
 446         /// an estimated cost of reaching this hop.
 447         /// Might get stale when fees are recomputed. Primarily for internal use.
 448         total_fee_msat: u64,
 449         /// A mirror of the same field in RouteGraphNode. Note that this is only used during the graph
 450         /// walk and may be invalid thereafter.
 451         path_htlc_minimum_msat: u64,
 452         /// All penalties incurred from this channel on the way to the destination, as calculated using
 453         /// channel scoring.
 454         path_penalty_msat: u64,
 455         /// If we've already processed a node as the best node, we shouldn't process it again. Normally
 456         /// we'd just ignore it if we did as all channels would have a higher new fee, but because we
 457         /// may decrease the amounts in use as we walk the graph, the actual calculated fee may
 458         /// decrease as well. Thus, we have to explicitly track which nodes have been processed and
 459         /// avoid processing them again.
 460         was_processed: bool,
 461         #[cfg(any(test, feature = "fuzztarget"))]
 462         // In tests, we apply further sanity checks on cases where we skip nodes we already processed
 463         // to ensure it is specifically in cases where the fee has gone down because of a decrease in
 464         // value_contribution_msat, which requires tracking it here. See comments below where it is
 465         // used for more info.
 466         value_contribution_msat: u64,
 467 }
 468
 469 // Instantiated with a list of hops with correct data in them collected during path finding,
 470 // an instance of this struct should be further modified only via given methods.
 471 #[derive(Clone)]
 472 struct PaymentPath<'a> {
 473         hops: Vec<(PathBuildingHop<'a>, NodeFeatures)>,
 474 }
 475
 476 impl<'a> PaymentPath<'a> {
 477         // TODO: Add a value_msat field to PaymentPath and use it instead of this function.
 478         fn get_value_msat(&self) -> u64 {
 479                 self.hops.last().unwrap().0.fee_msat
 480         }
 481
 482         fn get_total_fee_paid_msat(&self) -> u64 {
 483                 if self.hops.len() < 1 {
 484                         return 0;
 485                 }
 486                 let mut result = 0;
 487                 // Can't use next_hops_fee_msat because it gets outdated.
 488                 for (i, (hop, _)) in self.hops.iter().enumerate() {
 489                         if i != self.hops.len() - 1 {
 490                                 result += hop.fee_msat;
 491                         }
 492                 }
 493                 return result;
 494         }
 495
 496         // If the amount transferred by the path is updated, the fees should be adjusted. Any other way
 497         // to change fees may result in an inconsistency.
 498         //
 499         // Sometimes we call this function right after constructing a path which is inconsistent in
 500         // that it the value being transferred has decreased while we were doing path finding, leading
 501         // to the fees being paid not lining up with the actual limits.
 502         //
 503         // Note that this function is not aware of the available_liquidity limit, and thus does not
 504         // support increasing the value being transferred.
 505         fn update_value_and_recompute_fees(&mut self, value_msat: u64) {
 506                 assert!(value_msat <= self.hops.last().unwrap().0.fee_msat);
 507
 508                 let mut total_fee_paid_msat = 0 as u64;
 509                 for i in (0..self.hops.len()).rev() {
 510                         let last_hop = i == self.hops.len() - 1;
 511
 512                         // For non-last-hop, this value will represent the fees paid on the current hop. It
 513                         // will consist of the fees for the use of the next hop, and extra fees to match
 514                         // htlc_minimum_msat of the current channel. Last hop is handled separately.
 515                         let mut cur_hop_fees_msat = 0;
 516                         if !last_hop {
 517                                 cur_hop_fees_msat = self.hops.get(i + 1).unwrap().0.hop_use_fee_msat;
 518                         }
 519
 520                         let mut cur_hop = &mut self.hops.get_mut(i).unwrap().0;
 521                         cur_hop.next_hops_fee_msat = total_fee_paid_msat;
 522                         // Overpay in fees if we can't save these funds due to htlc_minimum_msat.
 523                         // We try to account for htlc_minimum_msat in scoring (add_entry!), so that nodes don't
 524                         // set it too high just to maliciously take more fees by exploiting this
 525                         // match htlc_minimum_msat logic.
 526                         let mut cur_hop_transferred_amount_msat = total_fee_paid_msat + value_msat;
 527                         if let Some(extra_fees_msat) = cur_hop.candidate.htlc_minimum_msat().checked_sub(cur_hop_transferred_amount_msat) {
 528                                 // Note that there is a risk that *previous hops* (those closer to us, as we go
 529                                 // payee->our_node here) would exceed their htlc_maximum_msat or available balance.
 530                                 //
 531                                 // This might make us end up with a broken route, although this should be super-rare
 532                                 // in practice, both because of how healthy channels look like, and how we pick
 533                                 // channels in add_entry.
 534                                 // Also, this can't be exploited more heavily than *announce a free path and fail
 535                                 // all payments*.
 536                                 cur_hop_transferred_amount_msat += extra_fees_msat;
 537                                 total_fee_paid_msat += extra_fees_msat;
 538                                 cur_hop_fees_msat += extra_fees_msat;
 539                         }
 540
 541                         if last_hop {
 542                                 // Final hop is a special case: it usually has just value_msat (by design), but also
 543                                 // it still could overpay for the htlc_minimum_msat.
 544                                 cur_hop.fee_msat = cur_hop_transferred_amount_msat;
 545                         } else {
 546                                 // Propagate updated fees for the use of the channels to one hop back, where they
 547                                 // will be actually paid (fee_msat). The last hop is handled above separately.
 548                                 cur_hop.fee_msat = cur_hop_fees_msat;
 549                         }
 550
 551                         // Fee for the use of the current hop which will be deducted on the previous hop.
 552                         // Irrelevant for the first hop, as it doesn't have the previous hop, and the use of
 553                         // this channel is free for us.
 554                         if i != 0 {
 555                                 if let Some(new_fee) = compute_fees(cur_hop_transferred_amount_msat, cur_hop.candidate.fees()) {
 556                                         cur_hop.hop_use_fee_msat = new_fee;
 557                                         total_fee_paid_msat += new_fee;
 558                                 } else {
 559                                         // It should not be possible because this function is called only to reduce the
 560                                         // value. In that case, compute_fee was already called with the same fees for
 561                                         // larger amount and there was no overflow.
 562                                         unreachable!();
 563                                 }
 564                         }
 565                 }
 566         }
 567 }
 568
 569 fn compute_fees(amount_msat: u64, channel_fees: RoutingFees) -> Option<u64> {
 570         let proportional_fee_millions =
 571                 amount_msat.checked_mul(channel_fees.proportional_millionths as u64);
 572         if let Some(new_fee) = proportional_fee_millions.and_then(|part| {
 573                         (channel_fees.base_msat as u64).checked_add(part / 1_000_000) }) {
 574
 575                 Some(new_fee)
 576         } else {
 577                 // This function may be (indirectly) called without any verification,
 578                 // with channel_fees provided by a caller. We should handle it gracefully.
 579                 None
 580         }
 581 }
 582
 583 /// Finds a route from us (payer) to the given target node (payee).
 584 ///
 585 /// If the payee provided features in their invoice, they should be provided via `params.payee`.
 586 /// Without this, MPP will only be used if the payee's features are available in the network graph.
 587 ///
 588 /// Private routing paths between a public node and the target may be included in `params.payee`.
 589 ///
 590 /// If some channels aren't announced, it may be useful to fill in `first_hops` with the results
 591 /// from [`ChannelManager::list_usable_channels`]. If it is filled in, the view of our local
 592 /// channels from [`NetworkGraph`] will be ignored, and only those in `first_hops` will be used.
 593 ///
 594 /// The fees on channels from us to the next hop are ignored as they are assumed to all be equal.
 595 /// However, the enabled/disabled bit on such channels as well as the `htlc_minimum_msat` /
 596 /// `htlc_maximum_msat` *are* checked as they may change based on the receiving node.
 597 ///
 598 /// # Note
 599 ///
 600 /// May be used to re-compute a [`Route`] when handling a [`Event::PaymentPathFailed`]. Any
 601 /// adjustments to the [`NetworkGraph`] and channel scores should be made prior to calling this
 602 /// function.
 603 ///
 604 /// # Panics
 605 ///
 606 /// Panics if first_hops contains channels without short_channel_ids;
 607 /// [`ChannelManager::list_usable_channels`] will never include such channels.
 608 ///
 609 /// [`ChannelManager::list_usable_channels`]: crate::ln::channelmanager::ChannelManager::list_usable_channels
 610 /// [`Event::PaymentPathFailed`]: crate::util::events::Event::PaymentPathFailed
 611 pub fn find_route<L: Deref, S: Score>(
 612         our_node_pubkey: &PublicKey, route_params: &RouteParameters, network: &NetworkGraph,
 613         first_hops: Option<&[&ChannelDetails]>, logger: L, scorer: &S
 614 ) -> Result<Route, LightningError>
 615 where L::Target: Logger {
 616         get_route(
 617                 our_node_pubkey, &route_params.payment_params, network, first_hops, route_params.final_value_msat,
 618                 route_params.final_cltv_expiry_delta, logger, scorer
 619         )
 620 }
 621
 622 pub(crate) fn get_route<L: Deref, S: Score>(
 623         our_node_pubkey: &PublicKey, payment_params: &PaymentParameters, network: &NetworkGraph,
 624         first_hops: Option<&[&ChannelDetails]>, final_value_msat: u64, final_cltv_expiry_delta: u32,
 625         logger: L, scorer: &S
 626 ) -> Result<Route, LightningError>
 627 where L::Target: Logger {
 628         let payee_node_id = NodeId::from_pubkey(&payment_params.payee_pubkey);
 629         let our_node_id = NodeId::from_pubkey(&our_node_pubkey);
 630
 631         if payee_node_id == our_node_id {
 632                 return Err(LightningError{err: "Cannot generate a route to ourselves".to_owned(), action: ErrorAction::IgnoreError});
 633         }
 634
 635         if final_value_msat > MAX_VALUE_MSAT {
 636                 return Err(LightningError{err: "Cannot generate a route of more value than all existing satoshis".to_owned(), action: ErrorAction::IgnoreError});
 637         }
 638
 639         if final_value_msat == 0 {
 640                 return Err(LightningError{err: "Cannot send a payment of 0 msat".to_owned(), action: ErrorAction::IgnoreError});
 641         }
 642
 643         for route in payment_params.route_hints.iter() {
 644                 for hop in &route.0 {
 645                         if hop.src_node_id == payment_params.payee_pubkey {
 646                                 return Err(LightningError{err: "Route hint cannot have the payee as the source.".to_owned(), action: ErrorAction::IgnoreError});
 647                         }
 648                 }
 649         }
 650
 651         // The general routing idea is the following:
 652         // 1. Fill first/last hops communicated by the caller.
 653         // 2. Attempt to construct a path from payer to payee for transferring
 654         //    any ~sufficient (described later) value.
 655         //    If succeed, remember which channels were used and how much liquidity they have available,
 656         //    so that future paths don't rely on the same liquidity.
 657         // 3. Proceed to the next step if:
 658         //    - we hit the recommended target value;
 659         //    - OR if we could not construct a new path. Any next attempt will fail too.
 660         //    Otherwise, repeat step 2.
 661         // 4. See if we managed to collect paths which aggregately are able to transfer target value
 662         //    (not recommended value). If yes, proceed. If not, fail routing.
 663         // 5. Randomly combine paths into routes having enough to fulfill the payment. (TODO: knapsack)
 664         // 6. Of all the found paths, select only those with the lowest total fee.
 665         // 7. The last path in every selected route is likely to be more than we need.
 666         //    Reduce its value-to-transfer and recompute fees.
 667         // 8. Choose the best route by the lowest total fee.
 668
 669         // As for the actual search algorithm,
 670         // we do a payee-to-payer pseudo-Dijkstra's sorting by each node's distance from the payee
 671         // plus the minimum per-HTLC fee to get from it to another node (aka "shitty pseudo-A*").
 672         //
 673         // We are not a faithful Dijkstra's implementation because we can change values which impact
 674         // earlier nodes while processing later nodes. Specifically, if we reach a channel with a lower
 675         // liquidity limit (via htlc_maximum_msat, on-chain capacity or assumed liquidity limits) than
 676         // the value we are currently attempting to send over a path, we simply reduce the value being
 677         // sent along the path for any hops after that channel. This may imply that later fees (which
 678         // we've already tabulated) are lower because a smaller value is passing through the channels
 679         // (and the proportional fee is thus lower). There isn't a trivial way to recalculate the
 680         // channels which were selected earlier (and which may still be used for other paths without a
 681         // lower liquidity limit), so we simply accept that some liquidity-limited paths may be
 682         // de-preferenced.
 683         //
 684         // One potentially problematic case for this algorithm would be if there are many
 685         // liquidity-limited paths which are liquidity-limited near the destination (ie early in our
 686         // graph walking), we may never find a path which is not liquidity-limited and has lower
 687         // proportional fee (and only lower absolute fee when considering the ultimate value sent).
 688         // Because we only consider paths with at least 5% of the total value being sent, the damage
 689         // from such a case should be limited, however this could be further reduced in the future by
 690         // calculating fees on the amount we wish to route over a path, ie ignoring the liquidity
 691         // limits for the purposes of fee calculation.
 692         //
 693         // Alternatively, we could store more detailed path information in the heap (targets, below)
 694         // and index the best-path map (dist, below) by node *and* HTLC limits, however that would blow
 695         // up the runtime significantly both algorithmically (as we'd traverse nodes multiple times)
 696         // and practically (as we would need to store dynamically-allocated path information in heap
 697         // objects, increasing malloc traffic and indirect memory access significantly). Further, the
 698         // results of such an algorithm would likely be biased towards lower-value paths.
 699         //
 700         // Further, we could return to a faithful Dijkstra's algorithm by rejecting paths with limits
 701         // outside of our current search value, running a path search more times to gather candidate
 702         // paths at different values. While this may be acceptable, further path searches may increase
 703         // runtime for little gain. Specifically, the current algorithm rather efficiently explores the
 704         // graph for candidate paths, calculating the maximum value which can realistically be sent at
 705         // the same time, remaining generic across different payment values.
 706         //
 707         // TODO: There are a few tweaks we could do, including possibly pre-calculating more stuff
 708         // to use as the A* heuristic beyond just the cost to get one node further than the current
 709         // one.
 710
 711         let network_graph = network.read_only();
 712         let network_channels = network_graph.channels();
 713         let network_nodes = network_graph.nodes();
 714
 715         // Allow MPP only if we have a features set from somewhere that indicates the payee supports
 716         // it. If the payee supports it they're supposed to include it in the invoice, so that should
 717         // work reliably.
 718         let allow_mpp = if let Some(features) = &payment_params.features {
 719                 features.supports_basic_mpp()
 720         } else if let Some(node) = network_nodes.get(&payee_node_id) {
 721                 if let Some(node_info) = node.announcement_info.as_ref() {
 722                         node_info.features.supports_basic_mpp()
 723                 } else { false }
 724         } else { false };
 725         log_trace!(logger, "Searching for a route from payer {} to payee {} {} MPP", our_node_pubkey,
 726                 payment_params.payee_pubkey, if allow_mpp { "with" } else { "without" });
 727
 728         // Step (1).
 729         // Prepare the data we'll use for payee-to-payer search by
 730         // inserting first hops suggested by the caller as targets.
 731         // Our search will then attempt to reach them while traversing from the payee node.
 732         let mut first_hop_targets: HashMap<_, Vec<&ChannelDetails>> =
 733                 HashMap::with_capacity(if first_hops.is_some() { first_hops.as_ref().unwrap().len() } else { 0 });
 734         if let Some(hops) = first_hops {
 735                 for chan in hops {
 736                         if chan.short_channel_id.is_none() {
 737                                 panic!("first_hops should be filled in with usable channels, not pending ones");
 738                         }
 739                         if chan.counterparty.node_id == *our_node_pubkey {
 740                                 return Err(LightningError{err: "First hop cannot have our_node_pubkey as a destination.".to_owned(), action: ErrorAction::IgnoreError});
 741                         }
 742                         first_hop_targets
 743                                 .entry(NodeId::from_pubkey(&chan.counterparty.node_id))
 744                                 .or_insert(Vec::new())
 745                                 .push(chan);
 746                 }
 747                 if first_hop_targets.is_empty() {
 748                         return Err(LightningError{err: "Cannot route when there are no outbound routes away from us".to_owned(), action: ErrorAction::IgnoreError});
 749                 }
 750         }
 751
 752         // The main heap containing all candidate next-hops sorted by their score (max(A* fee,
 753         // htlc_minimum)). Ideally this would be a heap which allowed cheap score reduction instead of
 754         // adding duplicate entries when we find a better path to a given node.
 755         let mut targets = BinaryHeap::new();
 756
 757         // Map from node_id to information about the best current path to that node, including feerate
 758         // information.
 759         let mut dist = HashMap::with_capacity(network_nodes.len());
 760
 761         // During routing, if we ignore a path due to an htlc_minimum_msat limit, we set this,
 762         // indicating that we may wish to try again with a higher value, potentially paying to meet an
 763         // htlc_minimum with extra fees while still finding a cheaper path.
 764         let mut hit_minimum_limit;
 765
 766         // When arranging a route, we select multiple paths so that we can make a multi-path payment.
 767         // We start with a path_value of the exact amount we want, and if that generates a route we may
 768         // return it immediately. Otherwise, we don't stop searching for paths until we have 3x the
 769         // amount we want in total across paths, selecting the best subset at the end.
 770         const ROUTE_CAPACITY_PROVISION_FACTOR: u64 = 3;
 771         let recommended_value_msat = final_value_msat * ROUTE_CAPACITY_PROVISION_FACTOR as u64;
 772         let mut path_value_msat = final_value_msat;
 773
 774         // We don't want multiple paths (as per MPP) share liquidity of the same channels.
 775         // This map allows paths to be aware of the channel use by other paths in the same call.
 776         // This would help to make a better path finding decisions and not "overbook" channels.
 777         // It is unaware of the directions (except for `outbound_capacity_msat` in `first_hops`).
 778         let mut bookkept_channels_liquidity_available_msat = HashMap::with_capacity(network_nodes.len());
 779
 780         // Keeping track of how much value we already collected across other paths. Helps to decide:
 781         // - how much a new path should be transferring (upper bound);
 782         // - whether a channel should be disregarded because
 783         //   it's available liquidity is too small comparing to how much more we need to collect;
 784         // - when we want to stop looking for new paths.
 785         let mut already_collected_value_msat = 0;
 786
 787         log_trace!(logger, "Building path from {} (payee) to {} (us/payer) for value {} msat.", payment_params.payee_pubkey, our_node_pubkey, final_value_msat);
 788
 789         macro_rules! add_entry {
 790                 // Adds entry which goes from $src_node_id to $dest_node_id over the $candidate hop.
 791                 // $next_hops_fee_msat represents the fees paid for using all the channels *after* this one,
 792                 // since that value has to be transferred over this channel.
 793                 // Returns whether this channel caused an update to `targets`.
 794                 ( $candidate: expr, $src_node_id: expr, $dest_node_id: expr, $next_hops_fee_msat: expr,
 795                    $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr,
 796                    $next_hops_path_penalty_msat: expr, $next_hops_cltv_delta: expr ) => { {
 797                         // We "return" whether we updated the path at the end, via this:
 798                         let mut did_add_update_path_to_src_node = false;
 799                         // Channels to self should not be used. This is more of belt-and-suspenders, because in
 800                         // practice these cases should be caught earlier:
 801                         // - for regular channels at channel announcement (TODO)
 802                         // - for first and last hops early in get_route
 803                         if $src_node_id != $dest_node_id {
 804                                 let short_channel_id = $candidate.short_channel_id();
 805                                 let available_liquidity_msat = bookkept_channels_liquidity_available_msat
 806                                         .entry(short_channel_id)
 807                                         .or_insert_with(|| $candidate.effective_capacity().as_msat());
 808
 809                                 // It is tricky to substract $next_hops_fee_msat from available liquidity here.
 810                                 // It may be misleading because we might later choose to reduce the value transferred
 811                                 // over these channels, and the channel which was insufficient might become sufficient.
 812                                 // Worst case: we drop a good channel here because it can't cover the high following
 813                                 // fees caused by one expensive channel, but then this channel could have been used
 814                                 // if the amount being transferred over this path is lower.
 815                                 // We do this for now, but this is a subject for removal.
 816                                 if let Some(available_value_contribution_msat) = available_liquidity_msat.checked_sub($next_hops_fee_msat) {
 817
 818                                         // Routing Fragmentation Mitigation heuristic:
 819                                         //
 820                                         // Routing fragmentation across many payment paths increases the overall routing
 821                                         // fees as you have irreducible routing fees per-link used (`fee_base_msat`).
 822                                         // Taking too many smaller paths also increases the chance of payment failure.
 823                                         // Thus to avoid this effect, we require from our collected links to provide
 824                                         // at least a minimal contribution to the recommended value yet-to-be-fulfilled.
 825                                         //
 826                                         // This requirement is currently 5% of the remaining-to-be-collected value.
 827                                         // This means as we successfully advance in our collection,
 828                                         // the absolute liquidity contribution is lowered,
 829                                         // thus increasing the number of potential channels to be selected.
 830
 831                                         // Derive the minimal liquidity contribution with a ratio of 20 (5%, rounded up)
 832                                         // or 100% if we're not allowed to do multipath payments.
 833                                         let minimal_value_contribution_msat: u64 = if allow_mpp {
 834                                                 (recommended_value_msat - already_collected_value_msat + 19) / 20
 835                                         } else {
 836                                                 final_value_msat
 837                                         };
 838                                         // Verify the liquidity offered by this channel complies to the minimal contribution.
 839                                         let contributes_sufficient_value = available_value_contribution_msat >= minimal_value_contribution_msat;
 840
 841                                         // Do not consider candidates that exceed the maximum total cltv expiry limit.
 842                                         let max_total_cltv_expiry_delta = payment_params.max_total_cltv_expiry_delta;
 843                                         let hop_total_cltv_delta = ($next_hops_cltv_delta as u32)
 844                                                 .checked_add($candidate.cltv_expiry_delta())
 845                                                 .unwrap_or(u32::max_value());
 846                                         let doesnt_exceed_cltv_delta_limit = hop_total_cltv_delta <= max_total_cltv_expiry_delta;
 847
 848                                         let value_contribution_msat = cmp::min(available_value_contribution_msat, $next_hops_value_contribution);
 849                                         // Includes paying fees for the use of the following channels.
 850                                         let amount_to_transfer_over_msat: u64 = match value_contribution_msat.checked_add($next_hops_fee_msat) {
 851                                                 Some(result) => result,
 852                                                 // Can't overflow due to how the values were computed right above.
 853                                                 None => unreachable!(),
 854                                         };
 855                                         #[allow(unused_comparisons)] // $next_hops_path_htlc_minimum_msat is 0 in some calls so rustc complains
 856                                         let over_path_minimum_msat = amount_to_transfer_over_msat >= $candidate.htlc_minimum_msat() &&
 857                                                 amount_to_transfer_over_msat >= $next_hops_path_htlc_minimum_msat;
 858
 859                                         // If HTLC minimum is larger than the amount we're going to transfer, we shouldn't
 860                                         // bother considering this channel.
 861                                         // Since we're choosing amount_to_transfer_over_msat as maximum possible, it can
 862                                         // be only reduced later (not increased), so this channel should just be skipped
 863                                         // as not sufficient.
 864                                         if !over_path_minimum_msat && doesnt_exceed_cltv_delta_limit {
 865                                                 hit_minimum_limit = true;
 866                                         } else if contributes_sufficient_value && doesnt_exceed_cltv_delta_limit {
 867                                                 // Note that low contribution here (limited by available_liquidity_msat)
 868                                                 // might violate htlc_minimum_msat on the hops which are next along the
 869                                                 // payment path (upstream to the payee). To avoid that, we recompute
 870                                                 // path fees knowing the final path contribution after constructing it.
 871                                                 let path_htlc_minimum_msat = compute_fees($next_hops_path_htlc_minimum_msat, $candidate.fees())
 872                                                         .and_then(|fee_msat| fee_msat.checked_add($next_hops_path_htlc_minimum_msat))
 873                                                         .map(|fee_msat| cmp::max(fee_msat, $candidate.htlc_minimum_msat()))
 874                                                         .unwrap_or_else(|| u64::max_value());
 875                                                 let hm_entry = dist.entry($src_node_id);
 876                                                 let old_entry = hm_entry.or_insert_with(|| {
 877                                                         // If there was previously no known way to access the source node
 878                                                         // (recall it goes payee-to-payer) of short_channel_id, first add a
 879                                                         // semi-dummy record just to compute the fees to reach the source node.
 880                                                         // This will affect our decision on selecting short_channel_id
 881                                                         // as a way to reach the $dest_node_id.
 882                                                         let mut fee_base_msat = u32::max_value();
 883                                                         let mut fee_proportional_millionths = u32::max_value();
 884                                                         if let Some(Some(fees)) = network_nodes.get(&$src_node_id).map(|node| node.lowest_inbound_channel_fees) {
 885                                                                 fee_base_msat = fees.base_msat;
 886                                                                 fee_proportional_millionths = fees.proportional_millionths;
 887                                                         }
 888                                                         PathBuildingHop {
 889                                                                 node_id: $dest_node_id.clone(),
 890                                                                 candidate: $candidate.clone(),
 891                                                                 fee_msat: 0,
 892                                                                 src_lowest_inbound_fees: RoutingFees {
 893                                                                         base_msat: fee_base_msat,
 894                                                                         proportional_millionths: fee_proportional_millionths,
 895                                                                 },
 896                                                                 next_hops_fee_msat: u64::max_value(),
 897                                                                 hop_use_fee_msat: u64::max_value(),
 898                                                                 total_fee_msat: u64::max_value(),
 899                                                                 path_htlc_minimum_msat,
 900                                                                 path_penalty_msat: u64::max_value(),
 901                                                                 was_processed: false,
 902                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 903                                                                 value_contribution_msat,
 904                                                         }
 905                                                 });
 906
 907                                                 #[allow(unused_mut)] // We only use the mut in cfg(test)
 908                                                 let mut should_process = !old_entry.was_processed;
 909                                                 #[cfg(any(test, feature = "fuzztarget"))]
 910                                                 {
 911                                                         // In test/fuzzing builds, we do extra checks to make sure the skipping
 912                                                         // of already-seen nodes only happens in cases we expect (see below).
 913                                                         if !should_process { should_process = true; }
 914                                                 }
 915
 916                                                 if should_process {
 917                                                         let mut hop_use_fee_msat = 0;
 918                                                         let mut total_fee_msat = $next_hops_fee_msat;
 919
 920                                                         // Ignore hop_use_fee_msat for channel-from-us as we assume all channels-from-us
 921                                                         // will have the same effective-fee
 922                                                         if $src_node_id != our_node_id {
 923                                                                 match compute_fees(amount_to_transfer_over_msat, $candidate.fees()) {
 924                                                                         // max_value means we'll always fail
 925                                                                         // the old_entry.total_fee_msat > total_fee_msat check
 926                                                                         None => total_fee_msat = u64::max_value(),
 927                                                                         Some(fee_msat) => {
 928                                                                                 hop_use_fee_msat = fee_msat;
 929                                                                                 total_fee_msat += hop_use_fee_msat;
 930                                                                                 // When calculating the lowest inbound fees to a node, we
 931                                                                                 // calculate fees here not based on the actual value we think
 932                                                                                 // will flow over this channel, but on the minimum value that
 933                                                                                 // we'll accept flowing over it. The minimum accepted value
 934                                                                                 // is a constant through each path collection run, ensuring
 935                                                                                 // consistent basis. Otherwise we may later find a
 936                                                                                 // different path to the source node that is more expensive,
 937                                                                                 // but which we consider to be cheaper because we are capacity
 938                                                                                 // constrained and the relative fee becomes lower.
 939                                                                                 match compute_fees(minimal_value_contribution_msat, old_entry.src_lowest_inbound_fees)
 940                                                                                                 .map(|a| a.checked_add(total_fee_msat)) {
 941                                                                                         Some(Some(v)) => {
 942                                                                                                 total_fee_msat = v;
 943                                                                                         },
 944                                                                                         _ => {
 945                                                                                                 total_fee_msat = u64::max_value();
 946                                                                                         }
 947                                                                                 };
 948                                                                         }
 949                                                                 }
 950                                                         }
 951
 952                                                         let path_penalty_msat = $next_hops_path_penalty_msat.checked_add(
 953                                                                 scorer.channel_penalty_msat(short_channel_id, amount_to_transfer_over_msat, *available_liquidity_msat,
 954                                                                         &$src_node_id, &$dest_node_id)).unwrap_or_else(|| u64::max_value());
 955                                                         let new_graph_node = RouteGraphNode {
 956                                                                 node_id: $src_node_id,
 957                                                                 lowest_fee_to_peer_through_node: total_fee_msat,
 958                                                                 lowest_fee_to_node: $next_hops_fee_msat as u64 + hop_use_fee_msat,
 959                                                                 total_cltv_delta: hop_total_cltv_delta,
 960                                                                 value_contribution_msat: value_contribution_msat,
 961                                                                 path_htlc_minimum_msat,
 962                                                                 path_penalty_msat,
 963                                                         };
 964
 965                                                         // Update the way of reaching $src_node_id with the given short_channel_id (from $dest_node_id),
 966                                                         // if this way is cheaper than the already known
 967                                                         // (considering the cost to "reach" this channel from the route destination,
 968                                                         // the cost of using this channel,
 969                                                         // and the cost of routing to the source node of this channel).
 970                                                         // Also, consider that htlc_minimum_msat_difference, because we might end up
 971                                                         // paying it. Consider the following exploit:
 972                                                         // we use 2 paths to transfer 1.5 BTC. One of them is 0-fee normal 1 BTC path,
 973                                                         // and for the other one we picked a 1sat-fee path with htlc_minimum_msat of
 974                                                         // 1 BTC. Now, since the latter is more expensive, we gonna try to cut it
 975                                                         // by 0.5 BTC, but then match htlc_minimum_msat by paying a fee of 0.5 BTC
 976                                                         // to this channel.
 977                                                         // Ideally the scoring could be smarter (e.g. 0.5*htlc_minimum_msat here),
 978                                                         // but it may require additional tracking - we don't want to double-count
 979                                                         // the fees included in $next_hops_path_htlc_minimum_msat, but also
 980                                                         // can't use something that may decrease on future hops.
 981                                                         let old_cost = cmp::max(old_entry.total_fee_msat, old_entry.path_htlc_minimum_msat)
 982                                                                 .checked_add(old_entry.path_penalty_msat)
 983                                                                 .unwrap_or_else(|| u64::max_value());
 984                                                         let new_cost = cmp::max(total_fee_msat, path_htlc_minimum_msat)
 985                                                                 .checked_add(path_penalty_msat)
 986                                                                 .unwrap_or_else(|| u64::max_value());
 987
 988                                                         if !old_entry.was_processed && new_cost < old_cost {
 989                                                                 targets.push(new_graph_node);
 990                                                                 old_entry.next_hops_fee_msat = $next_hops_fee_msat;
 991                                                                 old_entry.hop_use_fee_msat = hop_use_fee_msat;
 992                                                                 old_entry.total_fee_msat = total_fee_msat;
 993                                                                 old_entry.node_id = $dest_node_id.clone();
 994                                                                 old_entry.candidate = $candidate.clone();
 995                                                                 old_entry.fee_msat = 0; // This value will be later filled with hop_use_fee_msat of the following channel
 996                                                                 old_entry.path_htlc_minimum_msat = path_htlc_minimum_msat;
 997                                                                 old_entry.path_penalty_msat = path_penalty_msat;
 998                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 999                                                                 {
1000                                                                         old_entry.value_contribution_msat = value_contribution_msat;
1001                                                                 }
1002                                                                 did_add_update_path_to_src_node = true;
1003                                                         } else if old_entry.was_processed && new_cost < old_cost {
1004                                                                 #[cfg(any(test, feature = "fuzztarget"))]
1005                                                                 {
1006                                                                         // If we're skipping processing a node which was previously
1007                                                                         // processed even though we found another path to it with a
1008                                                                         // cheaper fee, check that it was because the second path we
1009                                                                         // found (which we are processing now) has a lower value
1010                                                                         // contribution due to an HTLC minimum limit.
1011                                                                         //
1012                                                                         // e.g. take a graph with two paths from node 1 to node 2, one
1013                                                                         // through channel A, and one through channel B. Channel A and
1014                                                                         // B are both in the to-process heap, with their scores set by
1015                                                                         // a higher htlc_minimum than fee.
1016                                                                         // Channel A is processed first, and the channels onwards from
1017                                                                         // node 1 are added to the to-process heap. Thereafter, we pop
1018                                                                         // Channel B off of the heap, note that it has a much more
1019                                                                         // restrictive htlc_maximum_msat, and recalculate the fees for
1020                                                                         // all of node 1's channels using the new, reduced, amount.
1021                                                                         //
1022                                                                         // This would be bogus - we'd be selecting a higher-fee path
1023                                                                         // with a lower htlc_maximum_msat instead of the one we'd
1024                                                                         // already decided to use.
1025                                                                         debug_assert!(path_htlc_minimum_msat < old_entry.path_htlc_minimum_msat);
1026                                                                         debug_assert!(
1027                                                                                 value_contribution_msat + path_penalty_msat <
1028                                                                                 old_entry.value_contribution_msat + old_entry.path_penalty_msat
1029                                                                         );
1030                                                                 }
1031                                                         }
1032                                                 }
1033                                         }
1034                                 }
1035                         }
1036                         did_add_update_path_to_src_node
1037                 } }
1038         }
1039
1040         let empty_node_features = NodeFeatures::empty();
1041         // Find ways (channels with destination) to reach a given node and store them
1042         // in the corresponding data structures (routing graph etc).
1043         // $fee_to_target_msat represents how much it costs to reach to this node from the payee,
1044         // meaning how much will be paid in fees after this node (to the best of our knowledge).
1045         // This data can later be helpful to optimize routing (pay lower fees).
1046         macro_rules! add_entries_to_cheapest_to_target_node {
1047                 ( $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, $next_hops_cltv_delta: expr ) => {
1048                         let skip_node = if let Some(elem) = dist.get_mut(&$node_id) {
1049                                 let was_processed = elem.was_processed;
1050                                 elem.was_processed = true;
1051                                 was_processed
1052                         } else {
1053                                 // Entries are added to dist in add_entry!() when there is a channel from a node.
1054                                 // Because there are no channels from payee, it will not have a dist entry at this point.
1055                                 // If we're processing any other node, it is always be the result of a channel from it.
1056                                 assert_eq!($node_id, payee_node_id);
1057                                 false
1058                         };
1059
1060                         if !skip_node {
1061                                 if let Some(first_channels) = first_hop_targets.get(&$node_id) {
1062                                         for details in first_channels {
1063                                                 let candidate = CandidateRouteHop::FirstHop { details };
1064                                                 add_entry!(candidate, our_node_id, $node_id, $fee_to_target_msat, $next_hops_value_contribution, $next_hops_path_htlc_minimum_msat, $next_hops_path_penalty_msat, $next_hops_cltv_delta);
1065                                         }
1066                                 }
1067
1068                                 let features = if let Some(node_info) = $node.announcement_info.as_ref() {
1069                                         &node_info.features
1070                                 } else {
1071                                         &empty_node_features
1072                                 };
1073
1074                                 if !features.requires_unknown_bits() {
1075                                         for chan_id in $node.channels.iter() {
1076                                                 let chan = network_channels.get(chan_id).unwrap();
1077                                                 if !chan.features.requires_unknown_bits() {
1078                                                         let directed_channel =
1079                                                                 chan.as_directed_to(&$node_id).expect("inconsistent NetworkGraph");
1080                                                         let source = directed_channel.source();
1081                                                         let target = directed_channel.target();
1082                                                         if first_hops.is_none() || *source != our_node_id {
1083                                                                 if let Some(direction) = directed_channel.direction() {
1084                                                                         if direction.enabled {
1085                                                                                 let candidate = CandidateRouteHop::PublicHop {
1086                                                                                         info: directed_channel.with_update().unwrap(),
1087                                                                                         short_channel_id: *chan_id,
1088                                                                                 };
1089                                                                                 add_entry!(candidate, *source, *target, $fee_to_target_msat, $next_hops_value_contribution, $next_hops_path_htlc_minimum_msat, $next_hops_path_penalty_msat, $next_hops_cltv_delta);
1090                                                                         }
1091                                                                 }
1092                                                         }
1093                                                 }
1094                                         }
1095                                 }
1096                         }
1097                 };
1098         }
1099
1100         let mut payment_paths = Vec::<PaymentPath>::new();
1101
1102         // TODO: diversify by nodes (so that all paths aren't doomed if one node is offline).
1103         'paths_collection: loop {
1104                 // For every new path, start from scratch, except
1105                 // bookkept_channels_liquidity_available_msat, which will improve
1106                 // the further iterations of path finding. Also don't erase first_hop_targets.
1107                 targets.clear();
1108                 dist.clear();
1109                 hit_minimum_limit = false;
1110
1111                 // If first hop is a private channel and the only way to reach the payee, this is the only
1112                 // place where it could be added.
1113                 if let Some(first_channels) = first_hop_targets.get(&payee_node_id) {
1114                         for details in first_channels {
1115                                 let candidate = CandidateRouteHop::FirstHop { details };
1116                                 let added = add_entry!(candidate, our_node_id, payee_node_id, 0, path_value_msat, 0, 0u64, 0);
1117                                 log_trace!(logger, "{} direct route to payee via SCID {}", if added { "Added" } else { "Skipped" }, candidate.short_channel_id());
1118                         }
1119                 }
1120
1121                 // Add the payee as a target, so that the payee-to-payer
1122                 // search algorithm knows what to start with.
1123                 match network_nodes.get(&payee_node_id) {
1124                         // The payee is not in our network graph, so nothing to add here.
1125                         // There is still a chance of reaching them via last_hops though,
1126                         // so don't yet fail the payment here.
1127                         // If not, targets.pop() will not even let us enter the loop in step 2.
1128                         None => {},
1129                         Some(node) => {
1130                                 add_entries_to_cheapest_to_target_node!(node, payee_node_id, 0, path_value_msat, 0, 0u64, 0);
1131                         },
1132                 }
1133
1134                 // Step (2).
1135                 // If a caller provided us with last hops, add them to routing targets. Since this happens
1136                 // earlier than general path finding, they will be somewhat prioritized, although currently
1137                 // it matters only if the fees are exactly the same.
1138                 for route in payment_params.route_hints.iter().filter(|route| !route.0.is_empty()) {
1139                         let first_hop_in_route = &(route.0)[0];
1140                         let have_hop_src_in_graph =
1141                                 // Only add the hops in this route to our candidate set if either
1142                                 // we have a direct channel to the first hop or the first hop is
1143                                 // in the regular network graph.
1144                                 first_hop_targets.get(&NodeId::from_pubkey(&first_hop_in_route.src_node_id)).is_some() ||
1145                                 network_nodes.get(&NodeId::from_pubkey(&first_hop_in_route.src_node_id)).is_some();
1146                         if have_hop_src_in_graph {
1147                                 // We start building the path from reverse, i.e., from payee
1148                                 // to the first RouteHintHop in the path.
1149                                 let hop_iter = route.0.iter().rev();
1150                                 let prev_hop_iter = core::iter::once(&payment_params.payee_pubkey).chain(
1151                                         route.0.iter().skip(1).rev().map(|hop| &hop.src_node_id));
1152                                 let mut hop_used = true;
1153                                 let mut aggregate_next_hops_fee_msat: u64 = 0;
1154                                 let mut aggregate_next_hops_path_htlc_minimum_msat: u64 = 0;
1155                                 let mut aggregate_next_hops_path_penalty_msat: u64 = 0;
1156                                 let mut aggregate_next_hops_cltv_delta: u32 = 0;
1157
1158                                 for (idx, (hop, prev_hop_id)) in hop_iter.zip(prev_hop_iter).enumerate() {
1159                                         let source = NodeId::from_pubkey(&hop.src_node_id);
1160                                         let target = NodeId::from_pubkey(&prev_hop_id);
1161                                         let candidate = network_channels
1162                                                 .get(&hop.short_channel_id)
1163                                                 .and_then(|channel| channel.as_directed_to(&target))
1164                                                 .and_then(|channel| channel.with_update())
1165                                                 .map(|info| CandidateRouteHop::PublicHop {
1166                                                         info,
1167                                                         short_channel_id: hop.short_channel_id,
1168                                                 })
1169                                                 .unwrap_or_else(|| CandidateRouteHop::PrivateHop { hint: hop });
1170                                         let capacity_msat = candidate.effective_capacity().as_msat();
1171                                         aggregate_next_hops_path_penalty_msat = aggregate_next_hops_path_penalty_msat
1172                                                 .checked_add(scorer.channel_penalty_msat(hop.short_channel_id, final_value_msat, capacity_msat, &source, &target))
1173                                                 .unwrap_or_else(|| u64::max_value());
1174
1175                                         aggregate_next_hops_cltv_delta = aggregate_next_hops_cltv_delta
1176                                                 .checked_add(hop.cltv_expiry_delta as u32)
1177                                                 .unwrap_or_else(|| u32::max_value());
1178
1179                                         if !add_entry!(candidate, source, target, aggregate_next_hops_fee_msat, path_value_msat, aggregate_next_hops_path_htlc_minimum_msat, aggregate_next_hops_path_penalty_msat, aggregate_next_hops_cltv_delta) {
1180                                                 // If this hop was not used then there is no use checking the preceding hops
1181                                                 // in the RouteHint. We can break by just searching for a direct channel between
1182                                                 // last checked hop and first_hop_targets
1183                                                 hop_used = false;
1184                                         }
1185
1186                                         // Searching for a direct channel between last checked hop and first_hop_targets
1187                                         if let Some(first_channels) = first_hop_targets.get(&NodeId::from_pubkey(&prev_hop_id)) {
1188                                                 for details in first_channels {
1189                                                         let candidate = CandidateRouteHop::FirstHop { details };
1190                                                         add_entry!(candidate, our_node_id, NodeId::from_pubkey(&prev_hop_id), aggregate_next_hops_fee_msat, path_value_msat, aggregate_next_hops_path_htlc_minimum_msat, aggregate_next_hops_path_penalty_msat, aggregate_next_hops_cltv_delta);
1191                                                 }
1192                                         }
1193
1194                                         if !hop_used {
1195                                                 break;
1196                                         }
1197
1198                                         // In the next values of the iterator, the aggregate fees already reflects
1199                                         // the sum of value sent from payer (final_value_msat) and routing fees
1200                                         // for the last node in the RouteHint. We need to just add the fees to
1201                                         // route through the current node so that the preceeding node (next iteration)
1202                                         // can use it.
1203                                         let hops_fee = compute_fees(aggregate_next_hops_fee_msat + final_value_msat, hop.fees)
1204                                                 .map_or(None, |inc| inc.checked_add(aggregate_next_hops_fee_msat));
1205                                         aggregate_next_hops_fee_msat = if let Some(val) = hops_fee { val } else { break; };
1206
1207                                         let hop_htlc_minimum_msat = candidate.htlc_minimum_msat();
1208                                         let hop_htlc_minimum_msat_inc = if let Some(val) = compute_fees(aggregate_next_hops_path_htlc_minimum_msat, hop.fees) { val } else { break; };
1209                                         let hops_path_htlc_minimum = aggregate_next_hops_path_htlc_minimum_msat
1210                                                 .checked_add(hop_htlc_minimum_msat_inc);
1211                                         aggregate_next_hops_path_htlc_minimum_msat = if let Some(val) = hops_path_htlc_minimum { cmp::max(hop_htlc_minimum_msat, val) } else { break; };
1212
1213                                         if idx == route.0.len() - 1 {
1214                                                 // The last hop in this iterator is the first hop in
1215                                                 // overall RouteHint.
1216                                                 // If this hop connects to a node with which we have a direct channel,
1217                                                 // ignore the network graph and, if the last hop was added, add our
1218                                                 // direct channel to the candidate set.
1219                                                 //
1220                                                 // Note that we *must* check if the last hop was added as `add_entry`
1221                                                 // always assumes that the third argument is a node to which we have a
1222                                                 // path.
1223                                                 if let Some(first_channels) = first_hop_targets.get(&NodeId::from_pubkey(&hop.src_node_id)) {
1224                                                         for details in first_channels {
1225                                                                 let candidate = CandidateRouteHop::FirstHop { details };
1226                                                                 add_entry!(candidate, our_node_id, NodeId::from_pubkey(&hop.src_node_id), aggregate_next_hops_fee_msat, path_value_msat, aggregate_next_hops_path_htlc_minimum_msat, aggregate_next_hops_path_penalty_msat, aggregate_next_hops_cltv_delta);
1227                                                         }
1228                                                 }
1229                                         }
1230                                 }
1231                         }
1232                 }
1233
1234                 log_trace!(logger, "Starting main path collection loop with {} nodes pre-filled from first/last hops.", targets.len());
1235
1236                 // At this point, targets are filled with the data from first and
1237                 // last hops communicated by the caller, and the payment receiver.
1238                 let mut found_new_path = false;
1239
1240                 // Step (3).
1241                 // If this loop terminates due the exhaustion of targets, two situations are possible:
1242                 // - not enough outgoing liquidity:
1243                 //   0 < already_collected_value_msat < final_value_msat
1244                 // - enough outgoing liquidity:
1245                 //   final_value_msat <= already_collected_value_msat < recommended_value_msat
1246                 // Both these cases (and other cases except reaching recommended_value_msat) mean that
1247                 // paths_collection will be stopped because found_new_path==false.
1248                 // This is not necessarily a routing failure.
1249                 'path_construction: while let Some(RouteGraphNode { node_id, lowest_fee_to_node, total_cltv_delta, value_contribution_msat, path_htlc_minimum_msat, path_penalty_msat, .. }) = targets.pop() {
1250
1251                         // Since we're going payee-to-payer, hitting our node as a target means we should stop
1252                         // traversing the graph and arrange the path out of what we found.
1253                         if node_id == our_node_id {
1254                                 let mut new_entry = dist.remove(&our_node_id).unwrap();
1255                                 let mut ordered_hops = vec!((new_entry.clone(), NodeFeatures::empty()));
1256
1257                                 'path_walk: loop {
1258                                         let mut features_set = false;
1259                                         if let Some(first_channels) = first_hop_targets.get(&ordered_hops.last().unwrap().0.node_id) {
1260                                                 for details in first_channels {
1261                                                         if details.short_channel_id.unwrap() == ordered_hops.last().unwrap().0.candidate.short_channel_id() {
1262                                                                 ordered_hops.last_mut().unwrap().1 = details.counterparty.features.to_context();
1263                                                                 features_set = true;
1264                                                                 break;
1265                                                         }
1266                                                 }
1267                                         }
1268                                         if !features_set {
1269                                                 if let Some(node) = network_nodes.get(&ordered_hops.last().unwrap().0.node_id) {
1270                                                         if let Some(node_info) = node.announcement_info.as_ref() {
1271                                                                 ordered_hops.last_mut().unwrap().1 = node_info.features.clone();
1272                                                         } else {
1273                                                                 ordered_hops.last_mut().unwrap().1 = NodeFeatures::empty();
1274                                                         }
1275                                                 } else {
1276                                                         // We should be able to fill in features for everything except the last
1277                                                         // hop, if the last hop was provided via a BOLT 11 invoice (though we
1278                                                         // should be able to extend it further as BOLT 11 does have feature
1279                                                         // flags for the last hop node itself).
1280                                                         assert!(ordered_hops.last().unwrap().0.node_id == payee_node_id);
1281                                                 }
1282                                         }
1283
1284                                         // Means we succesfully traversed from the payer to the payee, now
1285                                         // save this path for the payment route. Also, update the liquidity
1286                                         // remaining on the used hops, so that we take them into account
1287                                         // while looking for more paths.
1288                                         if ordered_hops.last().unwrap().0.node_id == payee_node_id {
1289                                                 break 'path_walk;
1290                                         }
1291
1292                                         new_entry = match dist.remove(&ordered_hops.last().unwrap().0.node_id) {
1293                                                 Some(payment_hop) => payment_hop,
1294                                                 // We can't arrive at None because, if we ever add an entry to targets,
1295                                                 // we also fill in the entry in dist (see add_entry!).
1296                                                 None => unreachable!(),
1297                                         };
1298                                         // We "propagate" the fees one hop backward (topologically) here,
1299                                         // so that fees paid for a HTLC forwarding on the current channel are
1300                                         // associated with the previous channel (where they will be subtracted).
1301                                         ordered_hops.last_mut().unwrap().0.fee_msat = new_entry.hop_use_fee_msat;
1302                                         ordered_hops.push((new_entry.clone(), NodeFeatures::empty()));
1303                                 }
1304                                 ordered_hops.last_mut().unwrap().0.fee_msat = value_contribution_msat;
1305                                 ordered_hops.last_mut().unwrap().0.hop_use_fee_msat = 0;
1306
1307                                 log_trace!(logger, "Found a path back to us from the target with {} hops contributing up to {} msat: {:?}",
1308                                         ordered_hops.len(), value_contribution_msat, ordered_hops);
1309
1310                                 let mut payment_path = PaymentPath {hops: ordered_hops};
1311
1312                                 // We could have possibly constructed a slightly inconsistent path: since we reduce
1313                                 // value being transferred along the way, we could have violated htlc_minimum_msat
1314                                 // on some channels we already passed (assuming dest->source direction). Here, we
1315                                 // recompute the fees again, so that if that's the case, we match the currently
1316                                 // underpaid htlc_minimum_msat with fees.
1317                                 payment_path.update_value_and_recompute_fees(cmp::min(value_contribution_msat, final_value_msat));
1318
1319                                 // Since a path allows to transfer as much value as
1320                                 // the smallest channel it has ("bottleneck"), we should recompute
1321                                 // the fees so sender HTLC don't overpay fees when traversing
1322                                 // larger channels than the bottleneck. This may happen because
1323                                 // when we were selecting those channels we were not aware how much value
1324                                 // this path will transfer, and the relative fee for them
1325                                 // might have been computed considering a larger value.
1326                                 // Remember that we used these channels so that we don't rely
1327                                 // on the same liquidity in future paths.
1328                                 let mut prevented_redundant_path_selection = false;
1329                                 for (payment_hop, _) in payment_path.hops.iter() {
1330                                         let channel_liquidity_available_msat = bookkept_channels_liquidity_available_msat.get_mut(&payment_hop.candidate.short_channel_id()).unwrap();
1331                                         let mut spent_on_hop_msat = value_contribution_msat;
1332                                         let next_hops_fee_msat = payment_hop.next_hops_fee_msat;
1333                                         spent_on_hop_msat += next_hops_fee_msat;
1334                                         if spent_on_hop_msat == *channel_liquidity_available_msat {
1335                                                 // If this path used all of this channel's available liquidity, we know
1336                                                 // this path will not be selected again in the next loop iteration.
1337                                                 prevented_redundant_path_selection = true;
1338                                         }
1339                                         *channel_liquidity_available_msat -= spent_on_hop_msat;
1340                                 }
1341                                 if !prevented_redundant_path_selection {
1342                                         // If we weren't capped by hitting a liquidity limit on a channel in the path,
1343                                         // we'll probably end up picking the same path again on the next iteration.
1344                                         // Decrease the available liquidity of a hop in the middle of the path.
1345                                         let victim_scid = payment_path.hops[(payment_path.hops.len() - 1) / 2].0.candidate.short_channel_id();
1346                                         log_trace!(logger, "Disabling channel {} for future path building iterations to avoid duplicates.", victim_scid);
1347                                         let victim_liquidity = bookkept_channels_liquidity_available_msat.get_mut(&victim_scid).unwrap();
1348                                         *victim_liquidity = 0;
1349                                 }
1350
1351                                 // Track the total amount all our collected paths allow to send so that we:
1352                                 // - know when to stop looking for more paths
1353                                 // - know which of the hops are useless considering how much more sats we need
1354                                 //   (contributes_sufficient_value)
1355                                 already_collected_value_msat += value_contribution_msat;
1356
1357                                 payment_paths.push(payment_path);
1358                                 found_new_path = true;
1359                                 break 'path_construction;
1360                         }
1361
1362                         // If we found a path back to the payee, we shouldn't try to process it again. This is
1363                         // the equivalent of the `elem.was_processed` check in
1364                         // add_entries_to_cheapest_to_target_node!() (see comment there for more info).
1365                         if node_id == payee_node_id { continue 'path_construction; }
1366
1367                         // Otherwise, since the current target node is not us,
1368                         // keep "unrolling" the payment graph from payee to payer by
1369                         // finding a way to reach the current target from the payer side.
1370                         match network_nodes.get(&node_id) {
1371                                 None => {},
1372                                 Some(node) => {
1373                                         add_entries_to_cheapest_to_target_node!(node, node_id, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat, path_penalty_msat, total_cltv_delta);
1374                                 },
1375                         }
1376                 }
1377
1378                 if !allow_mpp {
1379                         // If we don't support MPP, no use trying to gather more value ever.
1380                         break 'paths_collection;
1381                 }
1382
1383                 // Step (4).
1384                 // Stop either when the recommended value is reached or if no new path was found in this
1385                 // iteration.
1386                 // In the latter case, making another path finding attempt won't help,
1387                 // because we deterministically terminated the search due to low liquidity.
1388                 if already_collected_value_msat >= recommended_value_msat || !found_new_path {
1389                         log_trace!(logger, "Have now collected {} msat (seeking {} msat) in paths. Last path loop {} a new path.",
1390                                 already_collected_value_msat, recommended_value_msat, if found_new_path { "found" } else { "did not find" });
1391                         break 'paths_collection;
1392                 } else if found_new_path && already_collected_value_msat == final_value_msat && payment_paths.len() == 1 {
1393                         // Further, if this was our first walk of the graph, and we weren't limited by an
1394                         // htlc_minimum_msat, return immediately because this path should suffice. If we were
1395                         // limited by an htlc_minimum_msat value, find another path with a higher value,
1396                         // potentially allowing us to pay fees to meet the htlc_minimum on the new path while
1397                         // still keeping a lower total fee than this path.
1398                         if !hit_minimum_limit {
1399                                 log_trace!(logger, "Collected exactly our payment amount on the first pass, without hitting an htlc_minimum_msat limit, exiting.");
1400                                 break 'paths_collection;
1401                         }
1402                         log_trace!(logger, "Collected our payment amount on the first pass, but running again to collect extra paths with a potentially higher limit.");
1403                         path_value_msat = recommended_value_msat;
1404                 }
1405         }
1406
1407         // Step (5).
1408         if payment_paths.len() == 0 {
1409                 return Err(LightningError{err: "Failed to find a path to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1410         }
1411
1412         if already_collected_value_msat < final_value_msat {
1413                 return Err(LightningError{err: "Failed to find a sufficient route to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1414         }
1415
1416         // Sort by total fees and take the best paths.
1417         payment_paths.sort_by_key(|path| path.get_total_fee_paid_msat());
1418         if payment_paths.len() > 50 {
1419                 payment_paths.truncate(50);
1420         }
1421
1422         // Draw multiple sufficient routes by randomly combining the selected paths.
1423         let mut drawn_routes = Vec::new();
1424         for i in 0..payment_paths.len() {
1425                 let mut cur_route = Vec::<PaymentPath>::new();
1426                 let mut aggregate_route_value_msat = 0;
1427
1428                 // Step (6).
1429                 // TODO: real random shuffle
1430                 // Currently just starts with i_th and goes up to i-1_th in a looped way.
1431                 let cur_payment_paths = [&payment_paths[i..], &payment_paths[..i]].concat();
1432
1433                 // Step (7).
1434                 for payment_path in cur_payment_paths {
1435                         cur_route.push(payment_path.clone());
1436                         aggregate_route_value_msat += payment_path.get_value_msat();
1437                         if aggregate_route_value_msat > final_value_msat {
1438                                 // Last path likely overpaid. Substract it from the most expensive
1439                                 // (in terms of proportional fee) path in this route and recompute fees.
1440                                 // This might be not the most economically efficient way, but fewer paths
1441                                 // also makes routing more reliable.
1442                                 let mut overpaid_value_msat = aggregate_route_value_msat - final_value_msat;
1443
1444                                 // First, drop some expensive low-value paths entirely if possible.
1445                                 // Sort by value so that we drop many really-low values first, since
1446                                 // fewer paths is better: the payment is less likely to fail.
1447                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1448                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1449                                 cur_route.sort_by_key(|path| path.get_value_msat());
1450                                 // We should make sure that at least 1 path left.
1451                                 let mut paths_left = cur_route.len();
1452                                 cur_route.retain(|path| {
1453                                         if paths_left == 1 {
1454                                                 return true
1455                                         }
1456                                         let mut keep = true;
1457                                         let path_value_msat = path.get_value_msat();
1458                                         if path_value_msat <= overpaid_value_msat {
1459                                                 keep = false;
1460                                                 overpaid_value_msat -= path_value_msat;
1461                                                 paths_left -= 1;
1462                                         }
1463                                         keep
1464                                 });
1465
1466                                 if overpaid_value_msat == 0 {
1467                                         break;
1468                                 }
1469
1470                                 assert!(cur_route.len() > 0);
1471
1472                                 // Step (8).
1473                                 // Now, substract the overpaid value from the most-expensive path.
1474                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1475                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1476                                 cur_route.sort_by_key(|path| { path.hops.iter().map(|hop| hop.0.candidate.fees().proportional_millionths as u64).sum::<u64>() });
1477                                 let expensive_payment_path = cur_route.first_mut().unwrap();
1478                                 // We already dropped all the small channels above, meaning all the
1479                                 // remaining channels are larger than remaining overpaid_value_msat.
1480                                 // Thus, this can't be negative.
1481                                 let expensive_path_new_value_msat = expensive_payment_path.get_value_msat() - overpaid_value_msat;
1482                                 expensive_payment_path.update_value_and_recompute_fees(expensive_path_new_value_msat);
1483                                 break;
1484                         }
1485                 }
1486                 drawn_routes.push(cur_route);
1487         }
1488
1489         // Step (9).
1490         // Select the best route by lowest total fee.
1491         drawn_routes.sort_by_key(|paths| paths.iter().map(|path| path.get_total_fee_paid_msat()).sum::<u64>());
1492         let mut selected_paths = Vec::<Vec<Result<RouteHop, LightningError>>>::new();
1493         for payment_path in drawn_routes.first().unwrap() {
1494                 let mut path = payment_path.hops.iter().map(|(payment_hop, node_features)| {
1495                         Ok(RouteHop {
1496                                 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)})?,
1497                                 node_features: node_features.clone(),
1498                                 short_channel_id: payment_hop.candidate.short_channel_id(),
1499                                 channel_features: payment_hop.candidate.features(),
1500                                 fee_msat: payment_hop.fee_msat,
1501                                 cltv_expiry_delta: payment_hop.candidate.cltv_expiry_delta(),
1502                         })
1503                 }).collect::<Vec<_>>();
1504                 // Propagate the cltv_expiry_delta one hop backwards since the delta from the current hop is
1505                 // applicable for the previous hop.
1506                 path.iter_mut().rev().fold(final_cltv_expiry_delta, |prev_cltv_expiry_delta, hop| {
1507                         core::mem::replace(&mut hop.as_mut().unwrap().cltv_expiry_delta, prev_cltv_expiry_delta)
1508                 });
1509                 selected_paths.push(path);
1510         }
1511
1512         if let Some(features) = &payment_params.features {
1513                 for path in selected_paths.iter_mut() {
1514                         if let Ok(route_hop) = path.last_mut().unwrap() {
1515                                 route_hop.node_features = features.to_context();
1516                         }
1517                 }
1518         }
1519
1520         let route = Route {
1521                 paths: selected_paths.into_iter().map(|path| path.into_iter().collect()).collect::<Result<Vec<_>, _>>()?,
1522                 payment_params: Some(payment_params.clone()),
1523         };
1524         log_info!(logger, "Got route to {}: {}", payment_params.payee_pubkey, log_route!(route));
1525         Ok(route)
1526 }
1527
1528 #[cfg(test)]
1529 mod tests {
1530         use routing::scoring::Score;
1531         use routing::network_graph::{NetworkGraph, NetGraphMsgHandler, NodeId};
1532         use routing::router::{get_route, PaymentParameters, Route, RouteHint, RouteHintHop, RouteHop, RoutingFees};
1533         use chain::transaction::OutPoint;
1534         use ln::features::{ChannelFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
1535         use ln::msgs::{ErrorAction, LightningError, OptionalField, UnsignedChannelAnnouncement, ChannelAnnouncement, RoutingMessageHandler,
1536            NodeAnnouncement, UnsignedNodeAnnouncement, ChannelUpdate, UnsignedChannelUpdate};
1537         use ln::channelmanager;
1538         use util::test_utils;
1539         use util::ser::Writeable;
1540         #[cfg(c_bindings)]
1541         use util::ser::Writer;
1542
1543         use bitcoin::hashes::sha256d::Hash as Sha256dHash;
1544         use bitcoin::hashes::Hash;
1545         use bitcoin::network::constants::Network;
1546         use bitcoin::blockdata::constants::genesis_block;
1547         use bitcoin::blockdata::script::Builder;
1548         use bitcoin::blockdata::opcodes;
1549         use bitcoin::blockdata::transaction::TxOut;
1550
1551         use hex;
1552
1553         use bitcoin::secp256k1::key::{PublicKey,SecretKey};
1554         use bitcoin::secp256k1::{Secp256k1, All};
1555
1556         use prelude::*;
1557         use sync::{self, Arc};
1558
1559         fn get_channel_details(short_channel_id: Option<u64>, node_id: PublicKey,
1560                         features: InitFeatures, outbound_capacity_msat: u64) -> channelmanager::ChannelDetails {
1561                 channelmanager::ChannelDetails {
1562                         channel_id: [0; 32],
1563                         counterparty: channelmanager::ChannelCounterparty {
1564                                 features,
1565                                 node_id,
1566                                 unspendable_punishment_reserve: 0,
1567                                 forwarding_info: None,
1568                         },
1569                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
1570                         short_channel_id,
1571                         channel_value_satoshis: 0,
1572                         user_channel_id: 0,
1573                         balance_msat: 0,
1574                         outbound_capacity_msat,
1575                         inbound_capacity_msat: 42,
1576                         unspendable_punishment_reserve: None,
1577                         confirmations_required: None,
1578                         force_close_spend_delay: None,
1579                         is_outbound: true, is_funding_locked: true,
1580                         is_usable: true, is_public: true,
1581                 }
1582         }
1583
1584         // Using the same keys for LN and BTC ids
1585         fn add_channel(
1586                 net_graph_msg_handler: &NetGraphMsgHandler<Arc<NetworkGraph>, Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>,
1587                 secp_ctx: &Secp256k1<All>, node_1_privkey: &SecretKey, node_2_privkey: &SecretKey, features: ChannelFeatures, short_channel_id: u64
1588         ) {
1589                 let node_id_1 = PublicKey::from_secret_key(&secp_ctx, node_1_privkey);
1590                 let node_id_2 = PublicKey::from_secret_key(&secp_ctx, node_2_privkey);
1591
1592                 let unsigned_announcement = UnsignedChannelAnnouncement {
1593                         features,
1594                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1595                         short_channel_id,
1596                         node_id_1,
1597                         node_id_2,
1598                         bitcoin_key_1: node_id_1,
1599                         bitcoin_key_2: node_id_2,
1600                         excess_data: Vec::new(),
1601                 };
1602
1603                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1604                 let valid_announcement = ChannelAnnouncement {
1605                         node_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1606                         node_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1607                         bitcoin_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1608                         bitcoin_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1609                         contents: unsigned_announcement.clone(),
1610                 };
1611                 match net_graph_msg_handler.handle_channel_announcement(&valid_announcement) {
1612                         Ok(res) => assert!(res),
1613                         _ => panic!()
1614                 };
1615         }
1616
1617         fn update_channel(
1618                 net_graph_msg_handler: &NetGraphMsgHandler<Arc<NetworkGraph>, Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>,
1619                 secp_ctx: &Secp256k1<All>, node_privkey: &SecretKey, update: UnsignedChannelUpdate
1620         ) {
1621                 let msghash = hash_to_message!(&Sha256dHash::hash(&update.encode()[..])[..]);
1622                 let valid_channel_update = ChannelUpdate {
1623                         signature: secp_ctx.sign(&msghash, node_privkey),
1624                         contents: update.clone()
1625                 };
1626
1627                 match net_graph_msg_handler.handle_channel_update(&valid_channel_update) {
1628                         Ok(res) => assert!(res),
1629                         Err(_) => panic!()
1630                 };
1631         }
1632
1633         fn add_or_update_node(
1634                 net_graph_msg_handler: &NetGraphMsgHandler<Arc<NetworkGraph>, Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>,
1635                 secp_ctx: &Secp256k1<All>, node_privkey: &SecretKey, features: NodeFeatures, timestamp: u32
1636         ) {
1637                 let node_id = PublicKey::from_secret_key(&secp_ctx, node_privkey);
1638                 let unsigned_announcement = UnsignedNodeAnnouncement {
1639                         features,
1640                         timestamp,
1641                         node_id,
1642                         rgb: [0; 3],
1643                         alias: [0; 32],
1644                         addresses: Vec::new(),
1645                         excess_address_data: Vec::new(),
1646                         excess_data: Vec::new(),
1647                 };
1648                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1649                 let valid_announcement = NodeAnnouncement {
1650                         signature: secp_ctx.sign(&msghash, node_privkey),
1651                         contents: unsigned_announcement.clone()
1652                 };
1653
1654                 match net_graph_msg_handler.handle_node_announcement(&valid_announcement) {
1655                         Ok(_) => (),
1656                         Err(_) => panic!()
1657                 };
1658         }
1659
1660         fn get_nodes(secp_ctx: &Secp256k1<All>) -> (SecretKey, PublicKey, Vec<SecretKey>, Vec<PublicKey>) {
1661                 let privkeys: Vec<SecretKey> = (2..10).map(|i| {
1662                         SecretKey::from_slice(&hex::decode(format!("{:02}", i).repeat(32)).unwrap()[..]).unwrap()
1663                 }).collect();
1664
1665                 let pubkeys = privkeys.iter().map(|secret| PublicKey::from_secret_key(&secp_ctx, secret)).collect();
1666
1667                 let our_privkey = SecretKey::from_slice(&hex::decode("01".repeat(32)).unwrap()[..]).unwrap();
1668                 let our_id = PublicKey::from_secret_key(&secp_ctx, &our_privkey);
1669
1670                 (our_privkey, our_id, privkeys, pubkeys)
1671         }
1672
1673         fn id_to_feature_flags(id: u8) -> Vec<u8> {
1674                 // Set the feature flags to the id'th odd (ie non-required) feature bit so that we can
1675                 // test for it later.
1676                 let idx = (id - 1) * 2 + 1;
1677                 if idx > 8*3 {
1678                         vec![1 << (idx - 8*3), 0, 0, 0]
1679                 } else if idx > 8*2 {
1680                         vec![1 << (idx - 8*2), 0, 0]
1681                 } else if idx > 8*1 {
1682                         vec![1 << (idx - 8*1), 0]
1683                 } else {
1684                         vec![1 << idx]
1685                 }
1686         }
1687
1688         fn build_graph() -> (
1689                 Secp256k1<All>,
1690                 sync::Arc<NetworkGraph>,
1691                 NetGraphMsgHandler<sync::Arc<NetworkGraph>, sync::Arc<test_utils::TestChainSource>, sync::Arc<crate::util::test_utils::TestLogger>>,
1692                 sync::Arc<test_utils::TestChainSource>,
1693                 sync::Arc<test_utils::TestLogger>,
1694         ) {
1695                 let secp_ctx = Secp256k1::new();
1696                 let logger = Arc::new(test_utils::TestLogger::new());
1697                 let chain_monitor = Arc::new(test_utils::TestChainSource::new(Network::Testnet));
1698                 let network_graph = Arc::new(NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash()));
1699                 let net_graph_msg_handler = NetGraphMsgHandler::new(Arc::clone(&network_graph), None, Arc::clone(&logger));
1700                 // Build network from our_id to node6:
1701                 //
1702                 //        -1(1)2-  node0  -1(3)2-
1703                 //       /                       \
1704                 // our_id -1(12)2- node7 -1(13)2--- node2
1705                 //       \                       /
1706                 //        -1(2)2-  node1  -1(4)2-
1707                 //
1708                 //
1709                 // chan1  1-to-2: disabled
1710                 // chan1  2-to-1: enabled, 0 fee
1711                 //
1712                 // chan2  1-to-2: enabled, ignored fee
1713                 // chan2  2-to-1: enabled, 0 fee
1714                 //
1715                 // chan3  1-to-2: enabled, 0 fee
1716                 // chan3  2-to-1: enabled, 100 msat fee
1717                 //
1718                 // chan4  1-to-2: enabled, 100% fee
1719                 // chan4  2-to-1: enabled, 0 fee
1720                 //
1721                 // chan12 1-to-2: enabled, ignored fee
1722                 // chan12 2-to-1: enabled, 0 fee
1723                 //
1724                 // chan13 1-to-2: enabled, 200% fee
1725                 // chan13 2-to-1: enabled, 0 fee
1726                 //
1727                 //
1728                 //       -1(5)2- node3 -1(8)2--
1729                 //       |         2          |
1730                 //       |       (11)         |
1731                 //      /          1           \
1732                 // node2--1(6)2- node4 -1(9)2--- node6 (not in global route map)
1733                 //      \                      /
1734                 //       -1(7)2- node5 -1(10)2-
1735                 //
1736                 // Channels 5, 8, 9 and 10 are private channels.
1737                 //
1738                 // chan5  1-to-2: enabled, 100 msat fee
1739                 // chan5  2-to-1: enabled, 0 fee
1740                 //
1741                 // chan6  1-to-2: enabled, 0 fee
1742                 // chan6  2-to-1: enabled, 0 fee
1743                 //
1744                 // chan7  1-to-2: enabled, 100% fee
1745                 // chan7  2-to-1: enabled, 0 fee
1746                 //
1747                 // chan8  1-to-2: enabled, variable fee (0 then 1000 msat)
1748                 // chan8  2-to-1: enabled, 0 fee
1749                 //
1750                 // chan9  1-to-2: enabled, 1001 msat fee
1751                 // chan9  2-to-1: enabled, 0 fee
1752                 //
1753                 // chan10 1-to-2: enabled, 0 fee
1754                 // chan10 2-to-1: enabled, 0 fee
1755                 //
1756                 // chan11 1-to-2: enabled, 0 fee
1757                 // chan11 2-to-1: enabled, 0 fee
1758
1759                 let (our_privkey, _, privkeys, _) = get_nodes(&secp_ctx);
1760
1761                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[0], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
1762                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1763                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1764                         short_channel_id: 1,
1765                         timestamp: 1,
1766                         flags: 1,
1767                         cltv_expiry_delta: 0,
1768                         htlc_minimum_msat: 0,
1769                         htlc_maximum_msat: OptionalField::Absent,
1770                         fee_base_msat: 0,
1771                         fee_proportional_millionths: 0,
1772                         excess_data: Vec::new()
1773                 });
1774
1775                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
1776
1777                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
1778                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1779                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1780                         short_channel_id: 2,
1781                         timestamp: 1,
1782                         flags: 0,
1783                         cltv_expiry_delta: (5 << 4) | 3,
1784                         htlc_minimum_msat: 0,
1785                         htlc_maximum_msat: OptionalField::Absent,
1786                         fee_base_msat: u32::max_value(),
1787                         fee_proportional_millionths: u32::max_value(),
1788                         excess_data: Vec::new()
1789                 });
1790                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1791                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1792                         short_channel_id: 2,
1793                         timestamp: 1,
1794                         flags: 1,
1795                         cltv_expiry_delta: 0,
1796                         htlc_minimum_msat: 0,
1797                         htlc_maximum_msat: OptionalField::Absent,
1798                         fee_base_msat: 0,
1799                         fee_proportional_millionths: 0,
1800                         excess_data: Vec::new()
1801                 });
1802
1803                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
1804
1805                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[7], ChannelFeatures::from_le_bytes(id_to_feature_flags(12)), 12);
1806                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1807                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1808                         short_channel_id: 12,
1809                         timestamp: 1,
1810                         flags: 0,
1811                         cltv_expiry_delta: (5 << 4) | 3,
1812                         htlc_minimum_msat: 0,
1813                         htlc_maximum_msat: OptionalField::Absent,
1814                         fee_base_msat: u32::max_value(),
1815                         fee_proportional_millionths: u32::max_value(),
1816                         excess_data: Vec::new()
1817                 });
1818                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1819                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1820                         short_channel_id: 12,
1821                         timestamp: 1,
1822                         flags: 1,
1823                         cltv_expiry_delta: 0,
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
1831                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], NodeFeatures::from_le_bytes(id_to_feature_flags(8)), 0);
1832
1833                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
1834                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1835                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1836                         short_channel_id: 3,
1837                         timestamp: 1,
1838                         flags: 0,
1839                         cltv_expiry_delta: (3 << 4) | 1,
1840                         htlc_minimum_msat: 0,
1841                         htlc_maximum_msat: OptionalField::Absent,
1842                         fee_base_msat: 0,
1843                         fee_proportional_millionths: 0,
1844                         excess_data: Vec::new()
1845                 });
1846                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1847                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1848                         short_channel_id: 3,
1849                         timestamp: 1,
1850                         flags: 1,
1851                         cltv_expiry_delta: (3 << 4) | 2,
1852                         htlc_minimum_msat: 0,
1853                         htlc_maximum_msat: OptionalField::Absent,
1854                         fee_base_msat: 100,
1855                         fee_proportional_millionths: 0,
1856                         excess_data: Vec::new()
1857                 });
1858
1859                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
1860                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1861                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1862                         short_channel_id: 4,
1863                         timestamp: 1,
1864                         flags: 0,
1865                         cltv_expiry_delta: (4 << 4) | 1,
1866                         htlc_minimum_msat: 0,
1867                         htlc_maximum_msat: OptionalField::Absent,
1868                         fee_base_msat: 0,
1869                         fee_proportional_millionths: 1000000,
1870                         excess_data: Vec::new()
1871                 });
1872                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1873                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1874                         short_channel_id: 4,
1875                         timestamp: 1,
1876                         flags: 1,
1877                         cltv_expiry_delta: (4 << 4) | 2,
1878                         htlc_minimum_msat: 0,
1879                         htlc_maximum_msat: OptionalField::Absent,
1880                         fee_base_msat: 0,
1881                         fee_proportional_millionths: 0,
1882                         excess_data: Vec::new()
1883                 });
1884
1885                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(13)), 13);
1886                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1887                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1888                         short_channel_id: 13,
1889                         timestamp: 1,
1890                         flags: 0,
1891                         cltv_expiry_delta: (13 << 4) | 1,
1892                         htlc_minimum_msat: 0,
1893                         htlc_maximum_msat: OptionalField::Absent,
1894                         fee_base_msat: 0,
1895                         fee_proportional_millionths: 2000000,
1896                         excess_data: Vec::new()
1897                 });
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: 13,
1901                         timestamp: 1,
1902                         flags: 1,
1903                         cltv_expiry_delta: (13 << 4) | 2,
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
1911                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
1912
1913                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
1914                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1915                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1916                         short_channel_id: 6,
1917                         timestamp: 1,
1918                         flags: 0,
1919                         cltv_expiry_delta: (6 << 4) | 1,
1920                         htlc_minimum_msat: 0,
1921                         htlc_maximum_msat: OptionalField::Absent,
1922                         fee_base_msat: 0,
1923                         fee_proportional_millionths: 0,
1924                         excess_data: Vec::new()
1925                 });
1926                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1927                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1928                         short_channel_id: 6,
1929                         timestamp: 1,
1930                         flags: 1,
1931                         cltv_expiry_delta: (6 << 4) | 2,
1932                         htlc_minimum_msat: 0,
1933                         htlc_maximum_msat: OptionalField::Absent,
1934                         fee_base_msat: 0,
1935                         fee_proportional_millionths: 0,
1936                         excess_data: Vec::new(),
1937                 });
1938
1939                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(11)), 11);
1940                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1941                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1942                         short_channel_id: 11,
1943                         timestamp: 1,
1944                         flags: 0,
1945                         cltv_expiry_delta: (11 << 4) | 1,
1946                         htlc_minimum_msat: 0,
1947                         htlc_maximum_msat: OptionalField::Absent,
1948                         fee_base_msat: 0,
1949                         fee_proportional_millionths: 0,
1950                         excess_data: Vec::new()
1951                 });
1952                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
1953                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1954                         short_channel_id: 11,
1955                         timestamp: 1,
1956                         flags: 1,
1957                         cltv_expiry_delta: (11 << 4) | 2,
1958                         htlc_minimum_msat: 0,
1959                         htlc_maximum_msat: OptionalField::Absent,
1960                         fee_base_msat: 0,
1961                         fee_proportional_millionths: 0,
1962                         excess_data: Vec::new()
1963                 });
1964
1965                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(5)), 0);
1966
1967                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
1968
1969                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[5], ChannelFeatures::from_le_bytes(id_to_feature_flags(7)), 7);
1970                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1971                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1972                         short_channel_id: 7,
1973                         timestamp: 1,
1974                         flags: 0,
1975                         cltv_expiry_delta: (7 << 4) | 1,
1976                         htlc_minimum_msat: 0,
1977                         htlc_maximum_msat: OptionalField::Absent,
1978                         fee_base_msat: 0,
1979                         fee_proportional_millionths: 1000000,
1980                         excess_data: Vec::new()
1981                 });
1982                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[5], UnsignedChannelUpdate {
1983                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1984                         short_channel_id: 7,
1985                         timestamp: 1,
1986                         flags: 1,
1987                         cltv_expiry_delta: (7 << 4) | 2,
1988                         htlc_minimum_msat: 0,
1989                         htlc_maximum_msat: OptionalField::Absent,
1990                         fee_base_msat: 0,
1991                         fee_proportional_millionths: 0,
1992                         excess_data: Vec::new()
1993                 });
1994
1995                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[5], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
1996
1997                 (secp_ctx, network_graph, net_graph_msg_handler, chain_monitor, logger)
1998         }
1999
2000         #[test]
2001         fn simple_route_test() {
2002                 let (secp_ctx, network_graph, _, _, logger) = build_graph();
2003                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2004                 let payment_params = PaymentParameters::from_node_id(nodes[2]);
2005                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2006
2007                 // Simple route to 2 via 1
2008
2009                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &payment_params, &network_graph, None, 0, 42, Arc::clone(&logger), &scorer) {
2010                         assert_eq!(err, "Cannot send a payment of 0 msat");
2011                 } else { panic!(); }
2012
2013                 let route = get_route(&our_id, &payment_params, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
2014                 assert_eq!(route.paths[0].len(), 2);
2015
2016                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2017                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2018                 assert_eq!(route.paths[0][0].fee_msat, 100);
2019                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 4) | 1);
2020                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2021                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2022
2023                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2024                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2025                 assert_eq!(route.paths[0][1].fee_msat, 100);
2026                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2027                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2028                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2029         }
2030
2031         #[test]
2032         fn invalid_first_hop_test() {
2033                 let (secp_ctx, network_graph, _, _, logger) = build_graph();
2034                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2035                 let payment_params = PaymentParameters::from_node_id(nodes[2]);
2036                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2037
2038                 // Simple route to 2 via 1
2039
2040                 let our_chans = vec![get_channel_details(Some(2), our_id, InitFeatures::from_le_bytes(vec![0b11]), 100000)];
2041
2042                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &payment_params, &network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 100, 42, Arc::clone(&logger), &scorer) {
2043                         assert_eq!(err, "First hop cannot have our_node_pubkey as a destination.");
2044                 } else { panic!(); }
2045
2046                 let route = get_route(&our_id, &payment_params, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
2047                 assert_eq!(route.paths[0].len(), 2);
2048         }
2049
2050         #[test]
2051         fn htlc_minimum_test() {
2052                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
2053                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2054                 let payment_params = PaymentParameters::from_node_id(nodes[2]);
2055                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2056
2057                 // Simple route to 2 via 1
2058
2059                 // Disable other paths
2060                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2061                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2062                         short_channel_id: 12,
2063                         timestamp: 2,
2064                         flags: 2, // to disable
2065                         cltv_expiry_delta: 0,
2066                         htlc_minimum_msat: 0,
2067                         htlc_maximum_msat: OptionalField::Absent,
2068                         fee_base_msat: 0,
2069                         fee_proportional_millionths: 0,
2070                         excess_data: Vec::new()
2071                 });
2072                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2073                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2074                         short_channel_id: 3,
2075                         timestamp: 2,
2076                         flags: 2, // to disable
2077                         cltv_expiry_delta: 0,
2078                         htlc_minimum_msat: 0,
2079                         htlc_maximum_msat: OptionalField::Absent,
2080                         fee_base_msat: 0,
2081                         fee_proportional_millionths: 0,
2082                         excess_data: Vec::new()
2083                 });
2084                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2085                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2086                         short_channel_id: 13,
2087                         timestamp: 2,
2088                         flags: 2, // to disable
2089                         cltv_expiry_delta: 0,
2090                         htlc_minimum_msat: 0,
2091                         htlc_maximum_msat: OptionalField::Absent,
2092                         fee_base_msat: 0,
2093                         fee_proportional_millionths: 0,
2094                         excess_data: Vec::new()
2095                 });
2096                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2097                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2098                         short_channel_id: 6,
2099                         timestamp: 2,
2100                         flags: 2, // to disable
2101                         cltv_expiry_delta: 0,
2102                         htlc_minimum_msat: 0,
2103                         htlc_maximum_msat: OptionalField::Absent,
2104                         fee_base_msat: 0,
2105                         fee_proportional_millionths: 0,
2106                         excess_data: Vec::new()
2107                 });
2108                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2109                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2110                         short_channel_id: 7,
2111                         timestamp: 2,
2112                         flags: 2, // to disable
2113                         cltv_expiry_delta: 0,
2114                         htlc_minimum_msat: 0,
2115                         htlc_maximum_msat: OptionalField::Absent,
2116                         fee_base_msat: 0,
2117                         fee_proportional_millionths: 0,
2118                         excess_data: Vec::new()
2119                 });
2120
2121                 // Check against amount_to_transfer_over_msat.
2122                 // Set minimal HTLC of 200_000_000 msat.
2123                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2124                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2125                         short_channel_id: 2,
2126                         timestamp: 3,
2127                         flags: 0,
2128                         cltv_expiry_delta: 0,
2129                         htlc_minimum_msat: 200_000_000,
2130                         htlc_maximum_msat: OptionalField::Absent,
2131                         fee_base_msat: 0,
2132                         fee_proportional_millionths: 0,
2133                         excess_data: Vec::new()
2134                 });
2135
2136                 // Second hop only allows to forward 199_999_999 at most, thus not allowing the first hop to
2137                 // be used.
2138                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2139                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2140                         short_channel_id: 4,
2141                         timestamp: 3,
2142                         flags: 0,
2143                         cltv_expiry_delta: 0,
2144                         htlc_minimum_msat: 0,
2145                         htlc_maximum_msat: OptionalField::Present(199_999_999),
2146                         fee_base_msat: 0,
2147                         fee_proportional_millionths: 0,
2148                         excess_data: Vec::new()
2149                 });
2150
2151                 // Not possible to send 199_999_999, because the minimum on channel=2 is 200_000_000.
2152                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &payment_params, &network_graph, None, 199_999_999, 42, Arc::clone(&logger), &scorer) {
2153                         assert_eq!(err, "Failed to find a path to the given destination");
2154                 } else { panic!(); }
2155
2156                 // Lift the restriction on the first hop.
2157                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2158                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2159                         short_channel_id: 2,
2160                         timestamp: 4,
2161                         flags: 0,
2162                         cltv_expiry_delta: 0,
2163                         htlc_minimum_msat: 0,
2164                         htlc_maximum_msat: OptionalField::Absent,
2165                         fee_base_msat: 0,
2166                         fee_proportional_millionths: 0,
2167                         excess_data: Vec::new()
2168                 });
2169
2170                 // A payment above the minimum should pass
2171                 let route = get_route(&our_id, &payment_params, &network_graph, None, 199_999_999, 42, Arc::clone(&logger), &scorer).unwrap();
2172                 assert_eq!(route.paths[0].len(), 2);
2173         }
2174
2175         #[test]
2176         fn htlc_minimum_overpay_test() {
2177                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
2178                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2179                 let payment_params = PaymentParameters::from_node_id(nodes[2]).with_features(InvoiceFeatures::known());
2180                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2181
2182                 // A route to node#2 via two paths.
2183                 // One path allows transferring 35-40 sats, another one also allows 35-40 sats.
2184                 // Thus, they can't send 60 without overpaying.
2185                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2186                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2187                         short_channel_id: 2,
2188                         timestamp: 2,
2189                         flags: 0,
2190                         cltv_expiry_delta: 0,
2191                         htlc_minimum_msat: 35_000,
2192                         htlc_maximum_msat: OptionalField::Present(40_000),
2193                         fee_base_msat: 0,
2194                         fee_proportional_millionths: 0,
2195                         excess_data: Vec::new()
2196                 });
2197                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2198                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2199                         short_channel_id: 12,
2200                         timestamp: 3,
2201                         flags: 0,
2202                         cltv_expiry_delta: 0,
2203                         htlc_minimum_msat: 35_000,
2204                         htlc_maximum_msat: OptionalField::Present(40_000),
2205                         fee_base_msat: 0,
2206                         fee_proportional_millionths: 0,
2207                         excess_data: Vec::new()
2208                 });
2209
2210                 // Make 0 fee.
2211                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2212                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2213                         short_channel_id: 13,
2214                         timestamp: 2,
2215                         flags: 0,
2216                         cltv_expiry_delta: 0,
2217                         htlc_minimum_msat: 0,
2218                         htlc_maximum_msat: OptionalField::Absent,
2219                         fee_base_msat: 0,
2220                         fee_proportional_millionths: 0,
2221                         excess_data: Vec::new()
2222                 });
2223                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2224                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2225                         short_channel_id: 4,
2226                         timestamp: 2,
2227                         flags: 0,
2228                         cltv_expiry_delta: 0,
2229                         htlc_minimum_msat: 0,
2230                         htlc_maximum_msat: OptionalField::Absent,
2231                         fee_base_msat: 0,
2232                         fee_proportional_millionths: 0,
2233                         excess_data: Vec::new()
2234                 });
2235
2236                 // Disable other paths
2237                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2238                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2239                         short_channel_id: 1,
2240                         timestamp: 3,
2241                         flags: 2, // to disable
2242                         cltv_expiry_delta: 0,
2243                         htlc_minimum_msat: 0,
2244                         htlc_maximum_msat: OptionalField::Absent,
2245                         fee_base_msat: 0,
2246                         fee_proportional_millionths: 0,
2247                         excess_data: Vec::new()
2248                 });
2249
2250                 let route = get_route(&our_id, &payment_params, &network_graph, None, 60_000, 42, Arc::clone(&logger), &scorer).unwrap();
2251                 // Overpay fees to hit htlc_minimum_msat.
2252                 let overpaid_fees = route.paths[0][0].fee_msat + route.paths[1][0].fee_msat;
2253                 // TODO: this could be better balanced to overpay 10k and not 15k.
2254                 assert_eq!(overpaid_fees, 15_000);
2255
2256                 // Now, test that if there are 2 paths, a "cheaper" by fee path wouldn't be prioritized
2257                 // while taking even more fee to match htlc_minimum_msat.
2258                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2259                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2260                         short_channel_id: 12,
2261                         timestamp: 4,
2262                         flags: 0,
2263                         cltv_expiry_delta: 0,
2264                         htlc_minimum_msat: 65_000,
2265                         htlc_maximum_msat: OptionalField::Present(80_000),
2266                         fee_base_msat: 0,
2267                         fee_proportional_millionths: 0,
2268                         excess_data: Vec::new()
2269                 });
2270                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2271                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2272                         short_channel_id: 2,
2273                         timestamp: 3,
2274                         flags: 0,
2275                         cltv_expiry_delta: 0,
2276                         htlc_minimum_msat: 0,
2277                         htlc_maximum_msat: OptionalField::Absent,
2278                         fee_base_msat: 0,
2279                         fee_proportional_millionths: 0,
2280                         excess_data: Vec::new()
2281                 });
2282                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2283                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2284                         short_channel_id: 4,
2285                         timestamp: 4,
2286                         flags: 0,
2287                         cltv_expiry_delta: 0,
2288                         htlc_minimum_msat: 0,
2289                         htlc_maximum_msat: OptionalField::Absent,
2290                         fee_base_msat: 0,
2291                         fee_proportional_millionths: 100_000,
2292                         excess_data: Vec::new()
2293                 });
2294
2295                 let route = get_route(&our_id, &payment_params, &network_graph, None, 60_000, 42, Arc::clone(&logger), &scorer).unwrap();
2296                 // Fine to overpay for htlc_minimum_msat if it allows us to save fee.
2297                 assert_eq!(route.paths.len(), 1);
2298                 assert_eq!(route.paths[0][0].short_channel_id, 12);
2299                 let fees = route.paths[0][0].fee_msat;
2300                 assert_eq!(fees, 5_000);
2301
2302                 let route = get_route(&our_id, &payment_params, &network_graph, None, 50_000, 42, Arc::clone(&logger), &scorer).unwrap();
2303                 // Not fine to overpay for htlc_minimum_msat if it requires paying more than fee on
2304                 // the other channel.
2305                 assert_eq!(route.paths.len(), 1);
2306                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2307                 let fees = route.paths[0][0].fee_msat;
2308                 assert_eq!(fees, 5_000);
2309         }
2310
2311         #[test]
2312         fn disable_channels_test() {
2313                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
2314                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2315                 let payment_params = PaymentParameters::from_node_id(nodes[2]);
2316                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2317
2318                 // // Disable channels 4 and 12 by flags=2
2319                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2320                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2321                         short_channel_id: 4,
2322                         timestamp: 2,
2323                         flags: 2, // to disable
2324                         cltv_expiry_delta: 0,
2325                         htlc_minimum_msat: 0,
2326                         htlc_maximum_msat: OptionalField::Absent,
2327                         fee_base_msat: 0,
2328                         fee_proportional_millionths: 0,
2329                         excess_data: Vec::new()
2330                 });
2331                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2332                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2333                         short_channel_id: 12,
2334                         timestamp: 2,
2335                         flags: 2, // to disable
2336                         cltv_expiry_delta: 0,
2337                         htlc_minimum_msat: 0,
2338                         htlc_maximum_msat: OptionalField::Absent,
2339                         fee_base_msat: 0,
2340                         fee_proportional_millionths: 0,
2341                         excess_data: Vec::new()
2342                 });
2343
2344                 // If all the channels require some features we don't understand, route should fail
2345                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &payment_params, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer) {
2346                         assert_eq!(err, "Failed to find a path to the given destination");
2347                 } else { panic!(); }
2348
2349                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2350                 let our_chans = vec![get_channel_details(Some(42), nodes[7].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2351                 let route = get_route(&our_id, &payment_params, &network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 100, 42, Arc::clone(&logger), &scorer).unwrap();
2352                 assert_eq!(route.paths[0].len(), 2);
2353
2354                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2355                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2356                 assert_eq!(route.paths[0][0].fee_msat, 200);
2357                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 4) | 1);
2358                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
2359                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2360
2361                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2362                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2363                 assert_eq!(route.paths[0][1].fee_msat, 100);
2364                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2365                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2366                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2367         }
2368
2369         #[test]
2370         fn disable_node_test() {
2371                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
2372                 let (_, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2373                 let payment_params = PaymentParameters::from_node_id(nodes[2]);
2374                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2375
2376                 // Disable nodes 1, 2, and 8 by requiring unknown feature bits
2377                 let unknown_features = NodeFeatures::known().set_unknown_feature_required();
2378                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], unknown_features.clone(), 1);
2379                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], unknown_features.clone(), 1);
2380                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], unknown_features.clone(), 1);
2381
2382                 // If all nodes require some features we don't understand, route should fail
2383                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &payment_params, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer) {
2384                         assert_eq!(err, "Failed to find a path to the given destination");
2385                 } else { panic!(); }
2386
2387                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2388                 let our_chans = vec![get_channel_details(Some(42), nodes[7].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2389                 let route = get_route(&our_id, &payment_params, &network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 100, 42, Arc::clone(&logger), &scorer).unwrap();
2390                 assert_eq!(route.paths[0].len(), 2);
2391
2392                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2393                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2394                 assert_eq!(route.paths[0][0].fee_msat, 200);
2395                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 4) | 1);
2396                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
2397                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2398
2399                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2400                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2401                 assert_eq!(route.paths[0][1].fee_msat, 100);
2402                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2403                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2404                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2405
2406                 // Note that we don't test disabling node 3 and failing to route to it, as we (somewhat
2407                 // naively) assume that the user checked the feature bits on the invoice, which override
2408                 // the node_announcement.
2409         }
2410
2411         #[test]
2412         fn our_chans_test() {
2413                 let (secp_ctx, network_graph, _, _, logger) = build_graph();
2414                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2415                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2416
2417                 // Route to 1 via 2 and 3 because our channel to 1 is disabled
2418                 let payment_params = PaymentParameters::from_node_id(nodes[0]);
2419                 let route = get_route(&our_id, &payment_params, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
2420                 assert_eq!(route.paths[0].len(), 3);
2421
2422                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2423                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2424                 assert_eq!(route.paths[0][0].fee_msat, 200);
2425                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 4) | 1);
2426                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2427                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2428
2429                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2430                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2431                 assert_eq!(route.paths[0][1].fee_msat, 100);
2432                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (3 << 4) | 2);
2433                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2434                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2435
2436                 assert_eq!(route.paths[0][2].pubkey, nodes[0]);
2437                 assert_eq!(route.paths[0][2].short_channel_id, 3);
2438                 assert_eq!(route.paths[0][2].fee_msat, 100);
2439                 assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
2440                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(1));
2441                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(3));
2442
2443                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2444                 let payment_params = PaymentParameters::from_node_id(nodes[2]);
2445                 let our_chans = vec![get_channel_details(Some(42), nodes[7].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2446                 let route = get_route(&our_id, &payment_params, &network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 100, 42, Arc::clone(&logger), &scorer).unwrap();
2447                 assert_eq!(route.paths[0].len(), 2);
2448
2449                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2450                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2451                 assert_eq!(route.paths[0][0].fee_msat, 200);
2452                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 4) | 1);
2453                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2454                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2455
2456                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2457                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2458                 assert_eq!(route.paths[0][1].fee_msat, 100);
2459                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2460                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2461                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2462         }
2463
2464         fn last_hops(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2465                 let zero_fees = RoutingFees {
2466                         base_msat: 0,
2467                         proportional_millionths: 0,
2468                 };
2469                 vec![RouteHint(vec![RouteHintHop {
2470                         src_node_id: nodes[3],
2471                         short_channel_id: 8,
2472                         fees: zero_fees,
2473                         cltv_expiry_delta: (8 << 4) | 1,
2474                         htlc_minimum_msat: None,
2475                         htlc_maximum_msat: None,
2476                 }
2477                 ]), RouteHint(vec![RouteHintHop {
2478                         src_node_id: nodes[4],
2479                         short_channel_id: 9,
2480                         fees: RoutingFees {
2481                                 base_msat: 1001,
2482                                 proportional_millionths: 0,
2483                         },
2484                         cltv_expiry_delta: (9 << 4) | 1,
2485                         htlc_minimum_msat: None,
2486                         htlc_maximum_msat: None,
2487                 }]), RouteHint(vec![RouteHintHop {
2488                         src_node_id: nodes[5],
2489                         short_channel_id: 10,
2490                         fees: zero_fees,
2491                         cltv_expiry_delta: (10 << 4) | 1,
2492                         htlc_minimum_msat: None,
2493                         htlc_maximum_msat: None,
2494                 }])]
2495         }
2496
2497         fn last_hops_multi_private_channels(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2498                 let zero_fees = RoutingFees {
2499                         base_msat: 0,
2500                         proportional_millionths: 0,
2501                 };
2502                 vec![RouteHint(vec![RouteHintHop {
2503                         src_node_id: nodes[2],
2504                         short_channel_id: 5,
2505                         fees: RoutingFees {
2506                                 base_msat: 100,
2507                                 proportional_millionths: 0,
2508                         },
2509                         cltv_expiry_delta: (5 << 4) | 1,
2510                         htlc_minimum_msat: None,
2511                         htlc_maximum_msat: None,
2512                 }, RouteHintHop {
2513                         src_node_id: nodes[3],
2514                         short_channel_id: 8,
2515                         fees: zero_fees,
2516                         cltv_expiry_delta: (8 << 4) | 1,
2517                         htlc_minimum_msat: None,
2518                         htlc_maximum_msat: None,
2519                 }
2520                 ]), RouteHint(vec![RouteHintHop {
2521                         src_node_id: nodes[4],
2522                         short_channel_id: 9,
2523                         fees: RoutingFees {
2524                                 base_msat: 1001,
2525                                 proportional_millionths: 0,
2526                         },
2527                         cltv_expiry_delta: (9 << 4) | 1,
2528                         htlc_minimum_msat: None,
2529                         htlc_maximum_msat: None,
2530                 }]), RouteHint(vec![RouteHintHop {
2531                         src_node_id: nodes[5],
2532                         short_channel_id: 10,
2533                         fees: zero_fees,
2534                         cltv_expiry_delta: (10 << 4) | 1,
2535                         htlc_minimum_msat: None,
2536                         htlc_maximum_msat: None,
2537                 }])]
2538         }
2539
2540         #[test]
2541         fn partial_route_hint_test() {
2542                 let (secp_ctx, network_graph, _, _, logger) = build_graph();
2543                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2544                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2545
2546                 // Simple test across 2, 3, 5, and 4 via a last_hop channel
2547                 // Tests the behaviour when the RouteHint contains a suboptimal hop.
2548                 // RouteHint may be partially used by the algo to build the best path.
2549
2550                 // First check that last hop can't have its source as the payee.
2551                 let invalid_last_hop = RouteHint(vec![RouteHintHop {
2552                         src_node_id: nodes[6],
2553                         short_channel_id: 8,
2554                         fees: RoutingFees {
2555                                 base_msat: 1000,
2556                                 proportional_millionths: 0,
2557                         },
2558                         cltv_expiry_delta: (8 << 4) | 1,
2559                         htlc_minimum_msat: None,
2560                         htlc_maximum_msat: None,
2561                 }]);
2562
2563                 let mut invalid_last_hops = last_hops_multi_private_channels(&nodes);
2564                 invalid_last_hops.push(invalid_last_hop);
2565                 {
2566                         let payment_params = PaymentParameters::from_node_id(nodes[6]).with_route_hints(invalid_last_hops);
2567                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &payment_params, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer) {
2568                                 assert_eq!(err, "Route hint cannot have the payee as the source.");
2569                         } else { panic!(); }
2570                 }
2571
2572                 let payment_params = PaymentParameters::from_node_id(nodes[6]).with_route_hints(last_hops_multi_private_channels(&nodes));
2573                 let route = get_route(&our_id, &payment_params, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
2574                 assert_eq!(route.paths[0].len(), 5);
2575
2576                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2577                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2578                 assert_eq!(route.paths[0][0].fee_msat, 100);
2579                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 4) | 1);
2580                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2581                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2582
2583                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2584                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2585                 assert_eq!(route.paths[0][1].fee_msat, 0);
2586                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 4) | 1);
2587                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2588                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2589
2590                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2591                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2592                 assert_eq!(route.paths[0][2].fee_msat, 0);
2593                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 4) | 1);
2594                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2595                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2596
2597                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2598                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2599                 assert_eq!(route.paths[0][3].fee_msat, 0);
2600                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 4) | 1);
2601                 // If we have a peer in the node map, we'll use their features here since we don't have
2602                 // a way of figuring out their features from the invoice:
2603                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2604                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2605
2606                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2607                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2608                 assert_eq!(route.paths[0][4].fee_msat, 100);
2609                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2610                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2611                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2612         }
2613
2614         fn empty_last_hop(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2615                 let zero_fees = RoutingFees {
2616                         base_msat: 0,
2617                         proportional_millionths: 0,
2618                 };
2619                 vec![RouteHint(vec![RouteHintHop {
2620                         src_node_id: nodes[3],
2621                         short_channel_id: 8,
2622                         fees: zero_fees,
2623                         cltv_expiry_delta: (8 << 4) | 1,
2624                         htlc_minimum_msat: None,
2625                         htlc_maximum_msat: None,
2626                 }]), RouteHint(vec![
2627
2628                 ]), RouteHint(vec![RouteHintHop {
2629                         src_node_id: nodes[5],
2630                         short_channel_id: 10,
2631                         fees: zero_fees,
2632                         cltv_expiry_delta: (10 << 4) | 1,
2633                         htlc_minimum_msat: None,
2634                         htlc_maximum_msat: None,
2635                 }])]
2636         }
2637
2638         #[test]
2639         fn ignores_empty_last_hops_test() {
2640                 let (secp_ctx, network_graph, _, _, logger) = build_graph();
2641                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2642                 let payment_params = PaymentParameters::from_node_id(nodes[6]).with_route_hints(empty_last_hop(&nodes));
2643                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2644
2645                 // Test handling of an empty RouteHint passed in Invoice.
2646
2647                 let route = get_route(&our_id, &payment_params, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
2648                 assert_eq!(route.paths[0].len(), 5);
2649
2650                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2651                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2652                 assert_eq!(route.paths[0][0].fee_msat, 100);
2653                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 4) | 1);
2654                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2655                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2656
2657                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2658                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2659                 assert_eq!(route.paths[0][1].fee_msat, 0);
2660                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 4) | 1);
2661                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2662                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2663
2664                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2665                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2666                 assert_eq!(route.paths[0][2].fee_msat, 0);
2667                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 4) | 1);
2668                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2669                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2670
2671                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2672                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2673                 assert_eq!(route.paths[0][3].fee_msat, 0);
2674                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 4) | 1);
2675                 // If we have a peer in the node map, we'll use their features here since we don't have
2676                 // a way of figuring out their features from the invoice:
2677                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2678                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2679
2680                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2681                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2682                 assert_eq!(route.paths[0][4].fee_msat, 100);
2683                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2684                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2685                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2686         }
2687
2688         fn multi_hint_last_hops(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2689                 let zero_fees = RoutingFees {
2690                         base_msat: 0,
2691                         proportional_millionths: 0,
2692                 };
2693                 vec![RouteHint(vec![RouteHintHop {
2694                         src_node_id: nodes[2],
2695                         short_channel_id: 5,
2696                         fees: RoutingFees {
2697                                 base_msat: 100,
2698                                 proportional_millionths: 0,
2699                         },
2700                         cltv_expiry_delta: (5 << 4) | 1,
2701                         htlc_minimum_msat: None,
2702                         htlc_maximum_msat: None,
2703                 }, RouteHintHop {
2704                         src_node_id: nodes[3],
2705                         short_channel_id: 8,
2706                         fees: zero_fees,
2707                         cltv_expiry_delta: (8 << 4) | 1,
2708                         htlc_minimum_msat: None,
2709                         htlc_maximum_msat: None,
2710                 }]), RouteHint(vec![RouteHintHop {
2711                         src_node_id: nodes[5],
2712                         short_channel_id: 10,
2713                         fees: zero_fees,
2714                         cltv_expiry_delta: (10 << 4) | 1,
2715                         htlc_minimum_msat: None,
2716                         htlc_maximum_msat: None,
2717                 }])]
2718         }
2719
2720         #[test]
2721         fn multi_hint_last_hops_test() {
2722                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
2723                 let (_, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2724                 let payment_params = PaymentParameters::from_node_id(nodes[6]).with_route_hints(multi_hint_last_hops(&nodes));
2725                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2726                 // Test through channels 2, 3, 5, 8.
2727                 // Test shows that multiple hop hints are considered.
2728
2729                 // Disabling channels 6 & 7 by flags=2
2730                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2731                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2732                         short_channel_id: 6,
2733                         timestamp: 2,
2734                         flags: 2, // to disable
2735                         cltv_expiry_delta: 0,
2736                         htlc_minimum_msat: 0,
2737                         htlc_maximum_msat: OptionalField::Absent,
2738                         fee_base_msat: 0,
2739                         fee_proportional_millionths: 0,
2740                         excess_data: Vec::new()
2741                 });
2742                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2743                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2744                         short_channel_id: 7,
2745                         timestamp: 2,
2746                         flags: 2, // to disable
2747                         cltv_expiry_delta: 0,
2748                         htlc_minimum_msat: 0,
2749                         htlc_maximum_msat: OptionalField::Absent,
2750                         fee_base_msat: 0,
2751                         fee_proportional_millionths: 0,
2752                         excess_data: Vec::new()
2753                 });
2754
2755                 let route = get_route(&our_id, &payment_params, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
2756                 assert_eq!(route.paths[0].len(), 4);
2757
2758                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2759                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2760                 assert_eq!(route.paths[0][0].fee_msat, 200);
2761                 assert_eq!(route.paths[0][0].cltv_expiry_delta, 65);
2762                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2763                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2764
2765                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2766                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2767                 assert_eq!(route.paths[0][1].fee_msat, 100);
2768                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 81);
2769                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2770                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2771
2772                 assert_eq!(route.paths[0][2].pubkey, nodes[3]);
2773                 assert_eq!(route.paths[0][2].short_channel_id, 5);
2774                 assert_eq!(route.paths[0][2].fee_msat, 0);
2775                 assert_eq!(route.paths[0][2].cltv_expiry_delta, 129);
2776                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(4));
2777                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &Vec::<u8>::new());
2778
2779                 assert_eq!(route.paths[0][3].pubkey, nodes[6]);
2780                 assert_eq!(route.paths[0][3].short_channel_id, 8);
2781                 assert_eq!(route.paths[0][3].fee_msat, 100);
2782                 assert_eq!(route.paths[0][3].cltv_expiry_delta, 42);
2783                 assert_eq!(route.paths[0][3].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2784                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2785         }
2786
2787         fn last_hops_with_public_channel(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2788                 let zero_fees = RoutingFees {
2789                         base_msat: 0,
2790                         proportional_millionths: 0,
2791                 };
2792                 vec![RouteHint(vec![RouteHintHop {
2793                         src_node_id: nodes[4],
2794                         short_channel_id: 11,
2795                         fees: zero_fees,
2796                         cltv_expiry_delta: (11 << 4) | 1,
2797                         htlc_minimum_msat: None,
2798                         htlc_maximum_msat: None,
2799                 }, RouteHintHop {
2800                         src_node_id: nodes[3],
2801                         short_channel_id: 8,
2802                         fees: zero_fees,
2803                         cltv_expiry_delta: (8 << 4) | 1,
2804                         htlc_minimum_msat: None,
2805                         htlc_maximum_msat: None,
2806                 }]), RouteHint(vec![RouteHintHop {
2807                         src_node_id: nodes[4],
2808                         short_channel_id: 9,
2809                         fees: RoutingFees {
2810                                 base_msat: 1001,
2811                                 proportional_millionths: 0,
2812                         },
2813                         cltv_expiry_delta: (9 << 4) | 1,
2814                         htlc_minimum_msat: None,
2815                         htlc_maximum_msat: None,
2816                 }]), RouteHint(vec![RouteHintHop {
2817                         src_node_id: nodes[5],
2818                         short_channel_id: 10,
2819                         fees: zero_fees,
2820                         cltv_expiry_delta: (10 << 4) | 1,
2821                         htlc_minimum_msat: None,
2822                         htlc_maximum_msat: None,
2823                 }])]
2824         }
2825
2826         #[test]
2827         fn last_hops_with_public_channel_test() {
2828                 let (secp_ctx, network_graph, _, _, logger) = build_graph();
2829                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2830                 let payment_params = PaymentParameters::from_node_id(nodes[6]).with_route_hints(last_hops_with_public_channel(&nodes));
2831                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2832                 // This test shows that public routes can be present in the invoice
2833                 // which would be handled in the same manner.
2834
2835                 let route = get_route(&our_id, &payment_params, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
2836                 assert_eq!(route.paths[0].len(), 5);
2837
2838                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2839                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2840                 assert_eq!(route.paths[0][0].fee_msat, 100);
2841                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 4) | 1);
2842                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2843                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2844
2845                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2846                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2847                 assert_eq!(route.paths[0][1].fee_msat, 0);
2848                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 4) | 1);
2849                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2850                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2851
2852                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2853                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2854                 assert_eq!(route.paths[0][2].fee_msat, 0);
2855                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 4) | 1);
2856                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2857                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2858
2859                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2860                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2861                 assert_eq!(route.paths[0][3].fee_msat, 0);
2862                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 4) | 1);
2863                 // If we have a peer in the node map, we'll use their features here since we don't have
2864                 // a way of figuring out their features from the invoice:
2865                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2866                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2867
2868                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2869                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2870                 assert_eq!(route.paths[0][4].fee_msat, 100);
2871                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2872                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2873                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2874         }
2875
2876         #[test]
2877         fn our_chans_last_hop_connect_test() {
2878                 let (secp_ctx, network_graph, _, _, logger) = build_graph();
2879                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2880                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2881
2882                 // Simple test with outbound channel to 4 to test that last_hops and first_hops connect
2883                 let our_chans = vec![get_channel_details(Some(42), nodes[3].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2884                 let mut last_hops = last_hops(&nodes);
2885                 let payment_params = PaymentParameters::from_node_id(nodes[6]).with_route_hints(last_hops.clone());
2886                 let route = get_route(&our_id, &payment_params, &network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 100, 42, Arc::clone(&logger), &scorer).unwrap();
2887                 assert_eq!(route.paths[0].len(), 2);
2888
2889                 assert_eq!(route.paths[0][0].pubkey, nodes[3]);
2890                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2891                 assert_eq!(route.paths[0][0].fee_msat, 0);
2892                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 4) | 1);
2893                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2894                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2895
2896                 assert_eq!(route.paths[0][1].pubkey, nodes[6]);
2897                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2898                 assert_eq!(route.paths[0][1].fee_msat, 100);
2899                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2900                 assert_eq!(route.paths[0][1].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2901                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2902
2903                 last_hops[0].0[0].fees.base_msat = 1000;
2904
2905                 // Revert to via 6 as the fee on 8 goes up
2906                 let payment_params = PaymentParameters::from_node_id(nodes[6]).with_route_hints(last_hops);
2907                 let route = get_route(&our_id, &payment_params, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
2908                 assert_eq!(route.paths[0].len(), 4);
2909
2910                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2911                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2912                 assert_eq!(route.paths[0][0].fee_msat, 200); // fee increased as its % of value transferred across node
2913                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 4) | 1);
2914                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2915                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2916
2917                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2918                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2919                 assert_eq!(route.paths[0][1].fee_msat, 100);
2920                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (7 << 4) | 1);
2921                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2922                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2923
2924                 assert_eq!(route.paths[0][2].pubkey, nodes[5]);
2925                 assert_eq!(route.paths[0][2].short_channel_id, 7);
2926                 assert_eq!(route.paths[0][2].fee_msat, 0);
2927                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (10 << 4) | 1);
2928                 // If we have a peer in the node map, we'll use their features here since we don't have
2929                 // a way of figuring out their features from the invoice:
2930                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
2931                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(7));
2932
2933                 assert_eq!(route.paths[0][3].pubkey, nodes[6]);
2934                 assert_eq!(route.paths[0][3].short_channel_id, 10);
2935                 assert_eq!(route.paths[0][3].fee_msat, 100);
2936                 assert_eq!(route.paths[0][3].cltv_expiry_delta, 42);
2937                 assert_eq!(route.paths[0][3].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2938                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2939
2940                 // ...but still use 8 for larger payments as 6 has a variable feerate
2941                 let route = get_route(&our_id, &payment_params, &network_graph, None, 2000, 42, Arc::clone(&logger), &scorer).unwrap();
2942                 assert_eq!(route.paths[0].len(), 5);
2943
2944                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2945                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2946                 assert_eq!(route.paths[0][0].fee_msat, 3000);
2947                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 4) | 1);
2948                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2949                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2950
2951                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2952                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2953                 assert_eq!(route.paths[0][1].fee_msat, 0);
2954                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 4) | 1);
2955                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2956                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2957
2958                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2959                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2960                 assert_eq!(route.paths[0][2].fee_msat, 0);
2961                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 4) | 1);
2962                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2963                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2964
2965                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2966                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2967                 assert_eq!(route.paths[0][3].fee_msat, 1000);
2968                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 4) | 1);
2969                 // If we have a peer in the node map, we'll use their features here since we don't have
2970                 // a way of figuring out their features from the invoice:
2971                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2972                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2973
2974                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2975                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2976                 assert_eq!(route.paths[0][4].fee_msat, 2000);
2977                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2978                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2979                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2980         }
2981
2982         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> {
2983                 let source_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 41).repeat(32)).unwrap()[..]).unwrap());
2984                 let middle_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 42).repeat(32)).unwrap()[..]).unwrap());
2985                 let target_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 43).repeat(32)).unwrap()[..]).unwrap());
2986
2987                 // If we specify a channel to a middle hop, that overrides our local channel view and that gets used
2988                 let last_hops = RouteHint(vec![RouteHintHop {
2989                         src_node_id: middle_node_id,
2990                         short_channel_id: 8,
2991                         fees: RoutingFees {
2992                                 base_msat: 1000,
2993                                 proportional_millionths: last_hop_fee_prop,
2994                         },
2995                         cltv_expiry_delta: (8 << 4) | 1,
2996                         htlc_minimum_msat: None,
2997                         htlc_maximum_msat: last_hop_htlc_max,
2998                 }]);
2999                 let payment_params = PaymentParameters::from_node_id(target_node_id).with_route_hints(vec![last_hops]);
3000                 let our_chans = vec![get_channel_details(Some(42), middle_node_id, InitFeatures::from_le_bytes(vec![0b11]), outbound_capacity_msat)];
3001                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
3002                 get_route(&source_node_id, &payment_params, &NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash()), Some(&our_chans.iter().collect::<Vec<_>>()), route_val, 42, &test_utils::TestLogger::new(), &scorer)
3003         }
3004
3005         #[test]
3006         fn unannounced_path_test() {
3007                 // We should be able to send a payment to a destination without any help of a routing graph
3008                 // if we have a channel with a common counterparty that appears in the first and last hop
3009                 // hints.
3010                 let route = do_unannounced_path_test(None, 1, 2000000, 1000000).unwrap();
3011
3012                 let middle_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 42).repeat(32)).unwrap()[..]).unwrap());
3013                 let target_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 43).repeat(32)).unwrap()[..]).unwrap());
3014                 assert_eq!(route.paths[0].len(), 2);
3015
3016                 assert_eq!(route.paths[0][0].pubkey, middle_node_id);
3017                 assert_eq!(route.paths[0][0].short_channel_id, 42);
3018                 assert_eq!(route.paths[0][0].fee_msat, 1001);
3019                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 4) | 1);
3020                 assert_eq!(route.paths[0][0].node_features.le_flags(), &[0b11]);
3021                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
3022
3023                 assert_eq!(route.paths[0][1].pubkey, target_node_id);
3024                 assert_eq!(route.paths[0][1].short_channel_id, 8);
3025                 assert_eq!(route.paths[0][1].fee_msat, 1000000);
3026                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
3027                 assert_eq!(route.paths[0][1].node_features.le_flags(), &[0; 0]); // We dont pass flags in from invoices yet
3028                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
3029         }
3030
3031         #[test]
3032         fn overflow_unannounced_path_test_liquidity_underflow() {
3033                 // Previously, when we had a last-hop hint connected directly to a first-hop channel, where
3034                 // the last-hop had a fee which overflowed a u64, we'd panic.
3035                 // This was due to us adding the first-hop from us unconditionally, causing us to think
3036                 // we'd built a path (as our node is in the "best candidate" set), when we had not.
3037                 // In this test, we previously hit a subtraction underflow due to having less available
3038                 // liquidity at the last hop than 0.
3039                 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());
3040         }
3041
3042         #[test]
3043         fn overflow_unannounced_path_test_feerate_overflow() {
3044                 // This tests for the same case as above, except instead of hitting a subtraction
3045                 // underflow, we hit a case where the fee charged at a hop overflowed.
3046                 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());
3047         }
3048
3049         #[test]
3050         fn available_amount_while_routing_test() {
3051                 // Tests whether we choose the correct available channel amount while routing.
3052
3053                 let (secp_ctx, network_graph, mut net_graph_msg_handler, chain_monitor, logger) = build_graph();
3054                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3055                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
3056                 let payment_params = PaymentParameters::from_node_id(nodes[2]).with_features(InvoiceFeatures::known());
3057
3058                 // We will use a simple single-path route from
3059                 // our node to node2 via node0: channels {1, 3}.
3060
3061                 // First disable all other paths.
3062                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3063                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3064                         short_channel_id: 2,
3065                         timestamp: 2,
3066                         flags: 2,
3067                         cltv_expiry_delta: 0,
3068                         htlc_minimum_msat: 0,
3069                         htlc_maximum_msat: OptionalField::Present(100_000),
3070                         fee_base_msat: 0,
3071                         fee_proportional_millionths: 0,
3072                         excess_data: Vec::new()
3073                 });
3074                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3075                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3076                         short_channel_id: 12,
3077                         timestamp: 2,
3078                         flags: 2,
3079                         cltv_expiry_delta: 0,
3080                         htlc_minimum_msat: 0,
3081                         htlc_maximum_msat: OptionalField::Present(100_000),
3082                         fee_base_msat: 0,
3083                         fee_proportional_millionths: 0,
3084                         excess_data: Vec::new()
3085                 });
3086
3087                 // Make the first channel (#1) very permissive,
3088                 // and we will be testing all limits on the second channel.
3089                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3090                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3091                         short_channel_id: 1,
3092                         timestamp: 2,
3093                         flags: 0,
3094                         cltv_expiry_delta: 0,
3095                         htlc_minimum_msat: 0,
3096                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
3097                         fee_base_msat: 0,
3098                         fee_proportional_millionths: 0,
3099                         excess_data: Vec::new()
3100                 });
3101
3102                 // First, let's see if routing works if we have absolutely no idea about the available amount.
3103                 // In this case, it should be set to 250_000 sats.
3104                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3105                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3106                         short_channel_id: 3,
3107                         timestamp: 2,
3108                         flags: 0,
3109                         cltv_expiry_delta: 0,
3110                         htlc_minimum_msat: 0,
3111                         htlc_maximum_msat: OptionalField::Absent,
3112                         fee_base_msat: 0,
3113                         fee_proportional_millionths: 0,
3114                         excess_data: Vec::new()
3115                 });
3116
3117                 {
3118                         // Attempt to route more than available results in a failure.
3119                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3120                                         &our_id, &payment_params, &network_graph, None, 250_000_001, 42, Arc::clone(&logger), &scorer) {
3121                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3122                         } else { panic!(); }
3123                 }
3124
3125                 {
3126                         // Now, attempt to route an exact amount we have should be fine.
3127                         let route = get_route(&our_id, &payment_params, &network_graph, None, 250_000_000, 42, Arc::clone(&logger), &scorer).unwrap();
3128                         assert_eq!(route.paths.len(), 1);
3129                         let path = route.paths.last().unwrap();
3130                         assert_eq!(path.len(), 2);
3131                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3132                         assert_eq!(path.last().unwrap().fee_msat, 250_000_000);
3133                 }
3134
3135                 // Check that setting outbound_capacity_msat in first_hops limits the channels.
3136                 // Disable channel #1 and use another first hop.
3137                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3138                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3139                         short_channel_id: 1,
3140                         timestamp: 3,
3141                         flags: 2,
3142                         cltv_expiry_delta: 0,
3143                         htlc_minimum_msat: 0,
3144                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
3145                         fee_base_msat: 0,
3146                         fee_proportional_millionths: 0,
3147                         excess_data: Vec::new()
3148                 });
3149
3150                 // Now, limit the first_hop by the outbound_capacity_msat of 200_000 sats.
3151                 let our_chans = vec![get_channel_details(Some(42), nodes[0].clone(), InitFeatures::from_le_bytes(vec![0b11]), 200_000_000)];
3152
3153                 {
3154                         // Attempt to route more than available results in a failure.
3155                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3156                                         &our_id, &payment_params, &network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 200_000_001, 42, Arc::clone(&logger), &scorer) {
3157                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3158                         } else { panic!(); }
3159                 }
3160
3161                 {
3162                         // Now, attempt to route an exact amount we have should be fine.
3163                         let route = get_route(&our_id, &payment_params, &network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 200_000_000, 42, Arc::clone(&logger), &scorer).unwrap();
3164                         assert_eq!(route.paths.len(), 1);
3165                         let path = route.paths.last().unwrap();
3166                         assert_eq!(path.len(), 2);
3167                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3168                         assert_eq!(path.last().unwrap().fee_msat, 200_000_000);
3169                 }
3170
3171                 // Enable channel #1 back.
3172                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3173                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3174                         short_channel_id: 1,
3175                         timestamp: 4,
3176                         flags: 0,
3177                         cltv_expiry_delta: 0,
3178                         htlc_minimum_msat: 0,
3179                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
3180                         fee_base_msat: 0,
3181                         fee_proportional_millionths: 0,
3182                         excess_data: Vec::new()
3183                 });
3184
3185
3186                 // Now let's see if routing works if we know only htlc_maximum_msat.
3187                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3188                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3189                         short_channel_id: 3,
3190                         timestamp: 3,
3191                         flags: 0,
3192                         cltv_expiry_delta: 0,
3193                         htlc_minimum_msat: 0,
3194                         htlc_maximum_msat: OptionalField::Present(15_000),
3195                         fee_base_msat: 0,
3196                         fee_proportional_millionths: 0,
3197                         excess_data: Vec::new()
3198                 });
3199
3200                 {
3201                         // Attempt to route more than available results in a failure.
3202                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3203                                         &our_id, &payment_params, &network_graph, None, 15_001, 42, Arc::clone(&logger), &scorer) {
3204                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3205                         } else { panic!(); }
3206                 }
3207
3208                 {
3209                         // Now, attempt to route an exact amount we have should be fine.
3210                         let route = get_route(&our_id, &payment_params, &network_graph, None, 15_000, 42, Arc::clone(&logger), &scorer).unwrap();
3211                         assert_eq!(route.paths.len(), 1);
3212                         let path = route.paths.last().unwrap();
3213                         assert_eq!(path.len(), 2);
3214                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3215                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
3216                 }
3217
3218                 // Now let's see if routing works if we know only capacity from the UTXO.
3219
3220                 // We can't change UTXO capacity on the fly, so we'll disable
3221                 // the existing channel and add another one with the capacity we need.
3222                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3223                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3224                         short_channel_id: 3,
3225                         timestamp: 4,
3226                         flags: 2,
3227                         cltv_expiry_delta: 0,
3228                         htlc_minimum_msat: 0,
3229                         htlc_maximum_msat: OptionalField::Absent,
3230                         fee_base_msat: 0,
3231                         fee_proportional_millionths: 0,
3232                         excess_data: Vec::new()
3233                 });
3234
3235                 let good_script = Builder::new().push_opcode(opcodes::all::OP_PUSHNUM_2)
3236                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[0]).serialize())
3237                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[2]).serialize())
3238                 .push_opcode(opcodes::all::OP_PUSHNUM_2)
3239                 .push_opcode(opcodes::all::OP_CHECKMULTISIG).into_script().to_v0_p2wsh();
3240
3241                 *chain_monitor.utxo_ret.lock().unwrap() = Ok(TxOut { value: 15, script_pubkey: good_script.clone() });
3242                 net_graph_msg_handler.add_chain_access(Some(chain_monitor));
3243
3244                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 333);
3245                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3246                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3247                         short_channel_id: 333,
3248                         timestamp: 1,
3249                         flags: 0,
3250                         cltv_expiry_delta: (3 << 4) | 1,
3251                         htlc_minimum_msat: 0,
3252                         htlc_maximum_msat: OptionalField::Absent,
3253                         fee_base_msat: 0,
3254                         fee_proportional_millionths: 0,
3255                         excess_data: Vec::new()
3256                 });
3257                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3258                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3259                         short_channel_id: 333,
3260                         timestamp: 1,
3261                         flags: 1,
3262                         cltv_expiry_delta: (3 << 4) | 2,
3263                         htlc_minimum_msat: 0,
3264                         htlc_maximum_msat: OptionalField::Absent,
3265                         fee_base_msat: 100,
3266                         fee_proportional_millionths: 0,
3267                         excess_data: Vec::new()
3268                 });
3269
3270                 {
3271                         // Attempt to route more than available results in a failure.
3272                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3273                                         &our_id, &payment_params, &network_graph, None, 15_001, 42, Arc::clone(&logger), &scorer) {
3274                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3275                         } else { panic!(); }
3276                 }
3277
3278                 {
3279                         // Now, attempt to route an exact amount we have should be fine.
3280                         let route = get_route(&our_id, &payment_params, &network_graph, None, 15_000, 42, Arc::clone(&logger), &scorer).unwrap();
3281                         assert_eq!(route.paths.len(), 1);
3282                         let path = route.paths.last().unwrap();
3283                         assert_eq!(path.len(), 2);
3284                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3285                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
3286                 }
3287
3288                 // Now let's see if routing chooses htlc_maximum_msat over UTXO capacity.
3289                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3290                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3291                         short_channel_id: 333,
3292                         timestamp: 6,
3293                         flags: 0,
3294                         cltv_expiry_delta: 0,
3295                         htlc_minimum_msat: 0,
3296                         htlc_maximum_msat: OptionalField::Present(10_000),
3297                         fee_base_msat: 0,
3298                         fee_proportional_millionths: 0,
3299                         excess_data: Vec::new()
3300                 });
3301
3302                 {
3303                         // Attempt to route more than available results in a failure.
3304                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3305                                         &our_id, &payment_params, &network_graph, None, 10_001, 42, Arc::clone(&logger), &scorer) {
3306                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3307                         } else { panic!(); }
3308                 }
3309
3310                 {
3311                         // Now, attempt to route an exact amount we have should be fine.
3312                         let route = get_route(&our_id, &payment_params, &network_graph, None, 10_000, 42, Arc::clone(&logger), &scorer).unwrap();
3313                         assert_eq!(route.paths.len(), 1);
3314                         let path = route.paths.last().unwrap();
3315                         assert_eq!(path.len(), 2);
3316                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3317                         assert_eq!(path.last().unwrap().fee_msat, 10_000);
3318                 }
3319         }
3320
3321         #[test]
3322         fn available_liquidity_last_hop_test() {
3323                 // Check that available liquidity properly limits the path even when only
3324                 // one of the latter hops is limited.
3325                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
3326                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3327                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
3328                 let payment_params = PaymentParameters::from_node_id(nodes[3]).with_features(InvoiceFeatures::known());
3329
3330                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3331                 // {12, 13, 11} have the capacities of 100, {6} has a capacity of 50.
3332                 // Total capacity: 50 sats.
3333
3334                 // Disable other potential paths.
3335                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3336                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3337                         short_channel_id: 2,
3338                         timestamp: 2,
3339                         flags: 2,
3340                         cltv_expiry_delta: 0,
3341                         htlc_minimum_msat: 0,
3342                         htlc_maximum_msat: OptionalField::Present(100_000),
3343                         fee_base_msat: 0,
3344                         fee_proportional_millionths: 0,
3345                         excess_data: Vec::new()
3346                 });
3347                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3348                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3349                         short_channel_id: 7,
3350                         timestamp: 2,
3351                         flags: 2,
3352                         cltv_expiry_delta: 0,
3353                         htlc_minimum_msat: 0,
3354                         htlc_maximum_msat: OptionalField::Present(100_000),
3355                         fee_base_msat: 0,
3356                         fee_proportional_millionths: 0,
3357                         excess_data: Vec::new()
3358                 });
3359
3360                 // Limit capacities
3361
3362                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3363                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3364                         short_channel_id: 12,
3365                         timestamp: 2,
3366                         flags: 0,
3367                         cltv_expiry_delta: 0,
3368                         htlc_minimum_msat: 0,
3369                         htlc_maximum_msat: OptionalField::Present(100_000),
3370                         fee_base_msat: 0,
3371                         fee_proportional_millionths: 0,
3372                         excess_data: Vec::new()
3373                 });
3374                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3375                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3376                         short_channel_id: 13,
3377                         timestamp: 2,
3378                         flags: 0,
3379                         cltv_expiry_delta: 0,
3380                         htlc_minimum_msat: 0,
3381                         htlc_maximum_msat: OptionalField::Present(100_000),
3382                         fee_base_msat: 0,
3383                         fee_proportional_millionths: 0,
3384                         excess_data: Vec::new()
3385                 });
3386
3387                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3388                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3389                         short_channel_id: 6,
3390                         timestamp: 2,
3391                         flags: 0,
3392                         cltv_expiry_delta: 0,
3393                         htlc_minimum_msat: 0,
3394                         htlc_maximum_msat: OptionalField::Present(50_000),
3395                         fee_base_msat: 0,
3396                         fee_proportional_millionths: 0,
3397                         excess_data: Vec::new()
3398                 });
3399                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3400                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3401                         short_channel_id: 11,
3402                         timestamp: 2,
3403                         flags: 0,
3404                         cltv_expiry_delta: 0,
3405                         htlc_minimum_msat: 0,
3406                         htlc_maximum_msat: OptionalField::Present(100_000),
3407                         fee_base_msat: 0,
3408                         fee_proportional_millionths: 0,
3409                         excess_data: Vec::new()
3410                 });
3411                 {
3412                         // Attempt to route more than available results in a failure.
3413                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3414                                         &our_id, &payment_params, &network_graph, None, 60_000, 42, Arc::clone(&logger), &scorer) {
3415                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3416                         } else { panic!(); }
3417                 }
3418
3419                 {
3420                         // Now, attempt to route 49 sats (just a bit below the capacity).
3421                         let route = get_route(&our_id, &payment_params, &network_graph, None, 49_000, 42, Arc::clone(&logger), &scorer).unwrap();
3422                         assert_eq!(route.paths.len(), 1);
3423                         let mut total_amount_paid_msat = 0;
3424                         for path in &route.paths {
3425                                 assert_eq!(path.len(), 4);
3426                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3427                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3428                         }
3429                         assert_eq!(total_amount_paid_msat, 49_000);
3430                 }
3431
3432                 {
3433                         // Attempt to route an exact amount is also fine
3434                         let route = get_route(&our_id, &payment_params, &network_graph, None, 50_000, 42, Arc::clone(&logger), &scorer).unwrap();
3435                         assert_eq!(route.paths.len(), 1);
3436                         let mut total_amount_paid_msat = 0;
3437                         for path in &route.paths {
3438                                 assert_eq!(path.len(), 4);
3439                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3440                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3441                         }
3442                         assert_eq!(total_amount_paid_msat, 50_000);
3443                 }
3444         }
3445
3446         #[test]
3447         fn ignore_fee_first_hop_test() {
3448                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
3449                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3450                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
3451                 let payment_params = PaymentParameters::from_node_id(nodes[2]);
3452
3453                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
3454                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3455                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3456                         short_channel_id: 1,
3457                         timestamp: 2,
3458                         flags: 0,
3459                         cltv_expiry_delta: 0,
3460                         htlc_minimum_msat: 0,
3461                         htlc_maximum_msat: OptionalField::Present(100_000),
3462                         fee_base_msat: 1_000_000,
3463                         fee_proportional_millionths: 0,
3464                         excess_data: Vec::new()
3465                 });
3466                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3467                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3468                         short_channel_id: 3,
3469                         timestamp: 2,
3470                         flags: 0,
3471                         cltv_expiry_delta: 0,
3472                         htlc_minimum_msat: 0,
3473                         htlc_maximum_msat: OptionalField::Present(50_000),
3474                         fee_base_msat: 0,
3475                         fee_proportional_millionths: 0,
3476                         excess_data: Vec::new()
3477                 });
3478
3479                 {
3480                         let route = get_route(&our_id, &payment_params, &network_graph, None, 50_000, 42, Arc::clone(&logger), &scorer).unwrap();
3481                         assert_eq!(route.paths.len(), 1);
3482                         let mut total_amount_paid_msat = 0;
3483                         for path in &route.paths {
3484                                 assert_eq!(path.len(), 2);
3485                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3486                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3487                         }
3488                         assert_eq!(total_amount_paid_msat, 50_000);
3489                 }
3490         }
3491
3492         #[test]
3493         fn simple_mpp_route_test() {
3494                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
3495                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3496                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
3497                 let payment_params = PaymentParameters::from_node_id(nodes[2]).with_features(InvoiceFeatures::known());
3498
3499                 // We need a route consisting of 3 paths:
3500                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
3501                 // To achieve this, the amount being transferred should be around
3502                 // the total capacity of these 3 paths.
3503
3504                 // First, we set limits on these (previously unlimited) channels.
3505                 // Their aggregate capacity will be 50 + 60 + 180 = 290 sats.
3506
3507                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
3508                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3509                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3510                         short_channel_id: 1,
3511                         timestamp: 2,
3512                         flags: 0,
3513                         cltv_expiry_delta: 0,
3514                         htlc_minimum_msat: 0,
3515                         htlc_maximum_msat: OptionalField::Present(100_000),
3516                         fee_base_msat: 0,
3517                         fee_proportional_millionths: 0,
3518                         excess_data: Vec::new()
3519                 });
3520                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3521                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3522                         short_channel_id: 3,
3523                         timestamp: 2,
3524                         flags: 0,
3525                         cltv_expiry_delta: 0,
3526                         htlc_minimum_msat: 0,
3527                         htlc_maximum_msat: OptionalField::Present(50_000),
3528                         fee_base_msat: 0,
3529                         fee_proportional_millionths: 0,
3530                         excess_data: Vec::new()
3531                 });
3532
3533                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats
3534                 // (total limit 60).
3535                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3536                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3537                         short_channel_id: 12,
3538                         timestamp: 2,
3539                         flags: 0,
3540                         cltv_expiry_delta: 0,
3541                         htlc_minimum_msat: 0,
3542                         htlc_maximum_msat: OptionalField::Present(60_000),
3543                         fee_base_msat: 0,
3544                         fee_proportional_millionths: 0,
3545                         excess_data: Vec::new()
3546                 });
3547                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3548                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3549                         short_channel_id: 13,
3550                         timestamp: 2,
3551                         flags: 0,
3552                         cltv_expiry_delta: 0,
3553                         htlc_minimum_msat: 0,
3554                         htlc_maximum_msat: OptionalField::Present(60_000),
3555                         fee_base_msat: 0,
3556                         fee_proportional_millionths: 0,
3557                         excess_data: Vec::new()
3558                 });
3559
3560                 // Path via node1 is channels {2, 4}. Limit them to 200 and 180 sats
3561                 // (total capacity 180 sats).
3562                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3563                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3564                         short_channel_id: 2,
3565                         timestamp: 2,
3566                         flags: 0,
3567                         cltv_expiry_delta: 0,
3568                         htlc_minimum_msat: 0,
3569                         htlc_maximum_msat: OptionalField::Present(200_000),
3570                         fee_base_msat: 0,
3571                         fee_proportional_millionths: 0,
3572                         excess_data: Vec::new()
3573                 });
3574                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3575                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3576                         short_channel_id: 4,
3577                         timestamp: 2,
3578                         flags: 0,
3579                         cltv_expiry_delta: 0,
3580                         htlc_minimum_msat: 0,
3581                         htlc_maximum_msat: OptionalField::Present(180_000),
3582                         fee_base_msat: 0,
3583                         fee_proportional_millionths: 0,
3584                         excess_data: Vec::new()
3585                 });
3586
3587                 {
3588                         // Attempt to route more than available results in a failure.
3589                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3590                                         &our_id, &payment_params, &network_graph, None, 300_000, 42, Arc::clone(&logger), &scorer) {
3591                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3592                         } else { panic!(); }
3593                 }
3594
3595                 {
3596                         // Now, attempt to route 250 sats (just a bit below the capacity).
3597                         // Our algorithm should provide us with these 3 paths.
3598                         let route = get_route(&our_id, &payment_params, &network_graph, None, 250_000, 42, Arc::clone(&logger), &scorer).unwrap();
3599                         assert_eq!(route.paths.len(), 3);
3600                         let mut total_amount_paid_msat = 0;
3601                         for path in &route.paths {
3602                                 assert_eq!(path.len(), 2);
3603                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3604                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3605                         }
3606                         assert_eq!(total_amount_paid_msat, 250_000);
3607                 }
3608
3609                 {
3610                         // Attempt to route an exact amount is also fine
3611                         let route = get_route(&our_id, &payment_params, &network_graph, None, 290_000, 42, Arc::clone(&logger), &scorer).unwrap();
3612                         assert_eq!(route.paths.len(), 3);
3613                         let mut total_amount_paid_msat = 0;
3614                         for path in &route.paths {
3615                                 assert_eq!(path.len(), 2);
3616                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3617                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3618                         }
3619                         assert_eq!(total_amount_paid_msat, 290_000);
3620                 }
3621         }
3622
3623         #[test]
3624         fn long_mpp_route_test() {
3625                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
3626                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3627                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
3628                 let payment_params = PaymentParameters::from_node_id(nodes[3]).with_features(InvoiceFeatures::known());
3629
3630                 // We need a route consisting of 3 paths:
3631                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
3632                 // Note that these paths overlap (channels 5, 12, 13).
3633                 // We will route 300 sats.
3634                 // Each path will have 100 sats capacity, those channels which
3635                 // are used twice will have 200 sats capacity.
3636
3637                 // Disable other potential paths.
3638                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3639                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3640                         short_channel_id: 2,
3641                         timestamp: 2,
3642                         flags: 2,
3643                         cltv_expiry_delta: 0,
3644                         htlc_minimum_msat: 0,
3645                         htlc_maximum_msat: OptionalField::Present(100_000),
3646                         fee_base_msat: 0,
3647                         fee_proportional_millionths: 0,
3648                         excess_data: Vec::new()
3649                 });
3650                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3651                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3652                         short_channel_id: 7,
3653                         timestamp: 2,
3654                         flags: 2,
3655                         cltv_expiry_delta: 0,
3656                         htlc_minimum_msat: 0,
3657                         htlc_maximum_msat: OptionalField::Present(100_000),
3658                         fee_base_msat: 0,
3659                         fee_proportional_millionths: 0,
3660                         excess_data: Vec::new()
3661                 });
3662
3663                 // Path via {node0, node2} is channels {1, 3, 5}.
3664                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3665                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3666                         short_channel_id: 1,
3667                         timestamp: 2,
3668                         flags: 0,
3669                         cltv_expiry_delta: 0,
3670                         htlc_minimum_msat: 0,
3671                         htlc_maximum_msat: OptionalField::Present(100_000),
3672                         fee_base_msat: 0,
3673                         fee_proportional_millionths: 0,
3674                         excess_data: Vec::new()
3675                 });
3676                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3677                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3678                         short_channel_id: 3,
3679                         timestamp: 2,
3680                         flags: 0,
3681                         cltv_expiry_delta: 0,
3682                         htlc_minimum_msat: 0,
3683                         htlc_maximum_msat: OptionalField::Present(100_000),
3684                         fee_base_msat: 0,
3685                         fee_proportional_millionths: 0,
3686                         excess_data: Vec::new()
3687                 });
3688
3689                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3690                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3691                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3692                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3693                         short_channel_id: 5,
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
3704                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3705                 // Add 100 sats to the capacities of {12, 13}, because these channels
3706                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3707                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3708                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3709                         short_channel_id: 12,
3710                         timestamp: 2,
3711                         flags: 0,
3712                         cltv_expiry_delta: 0,
3713                         htlc_minimum_msat: 0,
3714                         htlc_maximum_msat: OptionalField::Present(200_000),
3715                         fee_base_msat: 0,
3716                         fee_proportional_millionths: 0,
3717                         excess_data: Vec::new()
3718                 });
3719                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3720                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3721                         short_channel_id: 13,
3722                         timestamp: 2,
3723                         flags: 0,
3724                         cltv_expiry_delta: 0,
3725                         htlc_minimum_msat: 0,
3726                         htlc_maximum_msat: OptionalField::Present(200_000),
3727                         fee_base_msat: 0,
3728                         fee_proportional_millionths: 0,
3729                         excess_data: Vec::new()
3730                 });
3731
3732                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3733                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3734                         short_channel_id: 6,
3735                         timestamp: 2,
3736                         flags: 0,
3737                         cltv_expiry_delta: 0,
3738                         htlc_minimum_msat: 0,
3739                         htlc_maximum_msat: OptionalField::Present(100_000),
3740                         fee_base_msat: 0,
3741                         fee_proportional_millionths: 0,
3742                         excess_data: Vec::new()
3743                 });
3744                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3745                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3746                         short_channel_id: 11,
3747                         timestamp: 2,
3748                         flags: 0,
3749                         cltv_expiry_delta: 0,
3750                         htlc_minimum_msat: 0,
3751                         htlc_maximum_msat: OptionalField::Present(100_000),
3752                         fee_base_msat: 0,
3753                         fee_proportional_millionths: 0,
3754                         excess_data: Vec::new()
3755                 });
3756
3757                 // Path via {node7, node2} is channels {12, 13, 5}.
3758                 // We already limited them to 200 sats (they are used twice for 100 sats).
3759                 // Nothing to do here.
3760
3761                 {
3762                         // Attempt to route more than available results in a failure.
3763                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3764                                         &our_id, &payment_params, &network_graph, None, 350_000, 42, Arc::clone(&logger), &scorer) {
3765                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3766                         } else { panic!(); }
3767                 }
3768
3769                 {
3770                         // Now, attempt to route 300 sats (exact amount we can route).
3771                         // Our algorithm should provide us with these 3 paths, 100 sats each.
3772                         let route = get_route(&our_id, &payment_params, &network_graph, None, 300_000, 42, Arc::clone(&logger), &scorer).unwrap();
3773                         assert_eq!(route.paths.len(), 3);
3774
3775                         let mut total_amount_paid_msat = 0;
3776                         for path in &route.paths {
3777                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3778                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3779                         }
3780                         assert_eq!(total_amount_paid_msat, 300_000);
3781                 }
3782
3783         }
3784
3785         #[test]
3786         fn mpp_cheaper_route_test() {
3787                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
3788                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3789                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
3790                 let payment_params = PaymentParameters::from_node_id(nodes[3]).with_features(InvoiceFeatures::known());
3791
3792                 // This test checks that if we have two cheaper paths and one more expensive path,
3793                 // so that liquidity-wise any 2 of 3 combination is sufficient,
3794                 // two cheaper paths will be taken.
3795                 // These paths have equal available liquidity.
3796
3797                 // We need a combination of 3 paths:
3798                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
3799                 // Note that these paths overlap (channels 5, 12, 13).
3800                 // Each path will have 100 sats capacity, those channels which
3801                 // are used twice will have 200 sats capacity.
3802
3803                 // Disable other potential paths.
3804                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3805                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3806                         short_channel_id: 2,
3807                         timestamp: 2,
3808                         flags: 2,
3809                         cltv_expiry_delta: 0,
3810                         htlc_minimum_msat: 0,
3811                         htlc_maximum_msat: OptionalField::Present(100_000),
3812                         fee_base_msat: 0,
3813                         fee_proportional_millionths: 0,
3814                         excess_data: Vec::new()
3815                 });
3816                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3817                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3818                         short_channel_id: 7,
3819                         timestamp: 2,
3820                         flags: 2,
3821                         cltv_expiry_delta: 0,
3822                         htlc_minimum_msat: 0,
3823                         htlc_maximum_msat: OptionalField::Present(100_000),
3824                         fee_base_msat: 0,
3825                         fee_proportional_millionths: 0,
3826                         excess_data: Vec::new()
3827                 });
3828
3829                 // Path via {node0, node2} is channels {1, 3, 5}.
3830                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3831                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3832                         short_channel_id: 1,
3833                         timestamp: 2,
3834                         flags: 0,
3835                         cltv_expiry_delta: 0,
3836                         htlc_minimum_msat: 0,
3837                         htlc_maximum_msat: OptionalField::Present(100_000),
3838                         fee_base_msat: 0,
3839                         fee_proportional_millionths: 0,
3840                         excess_data: Vec::new()
3841                 });
3842                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3843                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3844                         short_channel_id: 3,
3845                         timestamp: 2,
3846                         flags: 0,
3847                         cltv_expiry_delta: 0,
3848                         htlc_minimum_msat: 0,
3849                         htlc_maximum_msat: OptionalField::Present(100_000),
3850                         fee_base_msat: 0,
3851                         fee_proportional_millionths: 0,
3852                         excess_data: Vec::new()
3853                 });
3854
3855                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3856                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3857                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3858                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3859                         short_channel_id: 5,
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
3870                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3871                 // Add 100 sats to the capacities of {12, 13}, because these channels
3872                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3873                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3874                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3875                         short_channel_id: 12,
3876                         timestamp: 2,
3877                         flags: 0,
3878                         cltv_expiry_delta: 0,
3879                         htlc_minimum_msat: 0,
3880                         htlc_maximum_msat: OptionalField::Present(200_000),
3881                         fee_base_msat: 0,
3882                         fee_proportional_millionths: 0,
3883                         excess_data: Vec::new()
3884                 });
3885                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3886                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3887                         short_channel_id: 13,
3888                         timestamp: 2,
3889                         flags: 0,
3890                         cltv_expiry_delta: 0,
3891                         htlc_minimum_msat: 0,
3892                         htlc_maximum_msat: OptionalField::Present(200_000),
3893                         fee_base_msat: 0,
3894                         fee_proportional_millionths: 0,
3895                         excess_data: Vec::new()
3896                 });
3897
3898                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3899                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3900                         short_channel_id: 6,
3901                         timestamp: 2,
3902                         flags: 0,
3903                         cltv_expiry_delta: 0,
3904                         htlc_minimum_msat: 0,
3905                         htlc_maximum_msat: OptionalField::Present(100_000),
3906                         fee_base_msat: 1_000,
3907                         fee_proportional_millionths: 0,
3908                         excess_data: Vec::new()
3909                 });
3910                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3911                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3912                         short_channel_id: 11,
3913                         timestamp: 2,
3914                         flags: 0,
3915                         cltv_expiry_delta: 0,
3916                         htlc_minimum_msat: 0,
3917                         htlc_maximum_msat: OptionalField::Present(100_000),
3918                         fee_base_msat: 0,
3919                         fee_proportional_millionths: 0,
3920                         excess_data: Vec::new()
3921                 });
3922
3923                 // Path via {node7, node2} is channels {12, 13, 5}.
3924                 // We already limited them to 200 sats (they are used twice for 100 sats).
3925                 // Nothing to do here.
3926
3927                 {
3928                         // Now, attempt to route 180 sats.
3929                         // Our algorithm should provide us with these 2 paths.
3930                         let route = get_route(&our_id, &payment_params, &network_graph, None, 180_000, 42, Arc::clone(&logger), &scorer).unwrap();
3931                         assert_eq!(route.paths.len(), 2);
3932
3933                         let mut total_value_transferred_msat = 0;
3934                         let mut total_paid_msat = 0;
3935                         for path in &route.paths {
3936                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3937                                 total_value_transferred_msat += path.last().unwrap().fee_msat;
3938                                 for hop in path {
3939                                         total_paid_msat += hop.fee_msat;
3940                                 }
3941                         }
3942                         // If we paid fee, this would be higher.
3943                         assert_eq!(total_value_transferred_msat, 180_000);
3944                         let total_fees_paid = total_paid_msat - total_value_transferred_msat;
3945                         assert_eq!(total_fees_paid, 0);
3946                 }
3947         }
3948
3949         #[test]
3950         fn fees_on_mpp_route_test() {
3951                 // This test makes sure that MPP algorithm properly takes into account
3952                 // fees charged on the channels, by making the fees impactful:
3953                 // if the fee is not properly accounted for, the behavior is different.
3954                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
3955                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3956                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
3957                 let payment_params = PaymentParameters::from_node_id(nodes[3]).with_features(InvoiceFeatures::known());
3958
3959                 // We need a route consisting of 2 paths:
3960                 // From our node to node3 via {node0, node2} and {node7, node2, node4}.
3961                 // We will route 200 sats, Each path will have 100 sats capacity.
3962
3963                 // This test is not particularly stable: e.g.,
3964                 // there's a way to route via {node0, node2, node4}.
3965                 // It works while pathfinding is deterministic, but can be broken otherwise.
3966                 // It's fine to ignore this concern for now.
3967
3968                 // Disable other potential paths.
3969                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3970                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3971                         short_channel_id: 2,
3972                         timestamp: 2,
3973                         flags: 2,
3974                         cltv_expiry_delta: 0,
3975                         htlc_minimum_msat: 0,
3976                         htlc_maximum_msat: OptionalField::Present(100_000),
3977                         fee_base_msat: 0,
3978                         fee_proportional_millionths: 0,
3979                         excess_data: Vec::new()
3980                 });
3981
3982                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3983                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3984                         short_channel_id: 7,
3985                         timestamp: 2,
3986                         flags: 2,
3987                         cltv_expiry_delta: 0,
3988                         htlc_minimum_msat: 0,
3989                         htlc_maximum_msat: OptionalField::Present(100_000),
3990                         fee_base_msat: 0,
3991                         fee_proportional_millionths: 0,
3992                         excess_data: Vec::new()
3993                 });
3994
3995                 // Path via {node0, node2} is channels {1, 3, 5}.
3996                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3997                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3998                         short_channel_id: 1,
3999                         timestamp: 2,
4000                         flags: 0,
4001                         cltv_expiry_delta: 0,
4002                         htlc_minimum_msat: 0,
4003                         htlc_maximum_msat: OptionalField::Present(100_000),
4004                         fee_base_msat: 0,
4005                         fee_proportional_millionths: 0,
4006                         excess_data: Vec::new()
4007                 });
4008                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
4009                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4010                         short_channel_id: 3,
4011                         timestamp: 2,
4012                         flags: 0,
4013                         cltv_expiry_delta: 0,
4014                         htlc_minimum_msat: 0,
4015                         htlc_maximum_msat: OptionalField::Present(100_000),
4016                         fee_base_msat: 0,
4017                         fee_proportional_millionths: 0,
4018                         excess_data: Vec::new()
4019                 });
4020
4021                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
4022                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
4023                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4024                         short_channel_id: 5,
4025                         timestamp: 2,
4026                         flags: 0,
4027                         cltv_expiry_delta: 0,
4028                         htlc_minimum_msat: 0,
4029                         htlc_maximum_msat: OptionalField::Present(100_000),
4030                         fee_base_msat: 0,
4031                         fee_proportional_millionths: 0,
4032                         excess_data: Vec::new()
4033                 });
4034
4035                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
4036                 // All channels should be 100 sats capacity. But for the fee experiment,
4037                 // we'll add absolute fee of 150 sats paid for the use channel 6 (paid to node2 on channel 13).
4038                 // Since channel 12 allows to deliver only 250 sats to channel 13, channel 13 can transfer only
4039                 // 100 sats (and pay 150 sats in fees for the use of channel 6),
4040                 // so no matter how large are other channels,
4041                 // the whole path will be limited by 100 sats with just these 2 conditions:
4042                 // - channel 12 capacity is 250 sats
4043                 // - fee for channel 6 is 150 sats
4044                 // Let's test this by enforcing these 2 conditions and removing other limits.
4045                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4046                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4047                         short_channel_id: 12,
4048                         timestamp: 2,
4049                         flags: 0,
4050                         cltv_expiry_delta: 0,
4051                         htlc_minimum_msat: 0,
4052                         htlc_maximum_msat: OptionalField::Present(250_000),
4053                         fee_base_msat: 0,
4054                         fee_proportional_millionths: 0,
4055                         excess_data: Vec::new()
4056                 });
4057                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
4058                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4059                         short_channel_id: 13,
4060                         timestamp: 2,
4061                         flags: 0,
4062                         cltv_expiry_delta: 0,
4063                         htlc_minimum_msat: 0,
4064                         htlc_maximum_msat: OptionalField::Absent,
4065                         fee_base_msat: 0,
4066                         fee_proportional_millionths: 0,
4067                         excess_data: Vec::new()
4068                 });
4069
4070                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
4071                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4072                         short_channel_id: 6,
4073                         timestamp: 2,
4074                         flags: 0,
4075                         cltv_expiry_delta: 0,
4076                         htlc_minimum_msat: 0,
4077                         htlc_maximum_msat: OptionalField::Absent,
4078                         fee_base_msat: 150_000,
4079                         fee_proportional_millionths: 0,
4080                         excess_data: Vec::new()
4081                 });
4082                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
4083                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4084                         short_channel_id: 11,
4085                         timestamp: 2,
4086                         flags: 0,
4087                         cltv_expiry_delta: 0,
4088                         htlc_minimum_msat: 0,
4089                         htlc_maximum_msat: OptionalField::Absent,
4090                         fee_base_msat: 0,
4091                         fee_proportional_millionths: 0,
4092                         excess_data: Vec::new()
4093                 });
4094
4095                 {
4096                         // Attempt to route more than available results in a failure.
4097                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
4098                                         &our_id, &payment_params, &network_graph, None, 210_000, 42, Arc::clone(&logger), &scorer) {
4099                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
4100                         } else { panic!(); }
4101                 }
4102
4103                 {
4104                         // Now, attempt to route 200 sats (exact amount we can route).
4105                         let route = get_route(&our_id, &payment_params, &network_graph, None, 200_000, 42, Arc::clone(&logger), &scorer).unwrap();
4106                         assert_eq!(route.paths.len(), 2);
4107
4108                         let mut total_amount_paid_msat = 0;
4109                         for path in &route.paths {
4110                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
4111                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
4112                         }
4113                         assert_eq!(total_amount_paid_msat, 200_000);
4114                         assert_eq!(route.get_total_fees(), 150_000);
4115                 }
4116         }
4117
4118         #[test]
4119         fn mpp_with_last_hops() {
4120                 // Previously, if we tried to send an MPP payment to a destination which was only reachable
4121                 // via a single last-hop route hint, we'd fail to route if we first collected routes
4122                 // totaling close but not quite enough to fund the full payment.
4123                 //
4124                 // This was because we considered last-hop hints to have exactly the sought payment amount
4125                 // instead of the amount we were trying to collect, needlessly limiting our path searching
4126                 // at the very first hop.
4127                 //
4128                 // Specifically, this interacted with our "all paths must fund at least 5% of total target"
4129                 // criterion to cause us to refuse all routes at the last hop hint which would be considered
4130                 // to only have the remaining to-collect amount in available liquidity.
4131                 //
4132                 // This bug appeared in production in some specific channel configurations.
4133                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
4134                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
4135                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4136                 let payment_params = PaymentParameters::from_node_id(PublicKey::from_slice(&[02; 33]).unwrap()).with_features(InvoiceFeatures::known())
4137                         .with_route_hints(vec![RouteHint(vec![RouteHintHop {
4138                                 src_node_id: nodes[2],
4139                                 short_channel_id: 42,
4140                                 fees: RoutingFees { base_msat: 0, proportional_millionths: 0 },
4141                                 cltv_expiry_delta: 42,
4142                                 htlc_minimum_msat: None,
4143                                 htlc_maximum_msat: None,
4144                         }])]);
4145
4146                 // Keep only two paths from us to nodes[2], both with a 99sat HTLC maximum, with one with
4147                 // no fee and one with a 1msat fee. Previously, trying to route 100 sats to nodes[2] here
4148                 // would first use the no-fee route and then fail to find a path along the second route as
4149                 // we think we can only send up to 1 additional sat over the last-hop but refuse to as its
4150                 // under 5% of our payment amount.
4151                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4152                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4153                         short_channel_id: 1,
4154                         timestamp: 2,
4155                         flags: 0,
4156                         cltv_expiry_delta: (5 << 4) | 5,
4157                         htlc_minimum_msat: 0,
4158                         htlc_maximum_msat: OptionalField::Present(99_000),
4159                         fee_base_msat: u32::max_value(),
4160                         fee_proportional_millionths: u32::max_value(),
4161                         excess_data: Vec::new()
4162                 });
4163                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4164                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4165                         short_channel_id: 2,
4166                         timestamp: 2,
4167                         flags: 0,
4168                         cltv_expiry_delta: (5 << 4) | 3,
4169                         htlc_minimum_msat: 0,
4170                         htlc_maximum_msat: OptionalField::Present(99_000),
4171                         fee_base_msat: u32::max_value(),
4172                         fee_proportional_millionths: u32::max_value(),
4173                         excess_data: Vec::new()
4174                 });
4175                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
4176                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4177                         short_channel_id: 4,
4178                         timestamp: 2,
4179                         flags: 0,
4180                         cltv_expiry_delta: (4 << 4) | 1,
4181                         htlc_minimum_msat: 0,
4182                         htlc_maximum_msat: OptionalField::Absent,
4183                         fee_base_msat: 1,
4184                         fee_proportional_millionths: 0,
4185                         excess_data: Vec::new()
4186                 });
4187                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
4188                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4189                         short_channel_id: 13,
4190                         timestamp: 2,
4191                         flags: 0|2, // Channel disabled
4192                         cltv_expiry_delta: (13 << 4) | 1,
4193                         htlc_minimum_msat: 0,
4194                         htlc_maximum_msat: OptionalField::Absent,
4195                         fee_base_msat: 0,
4196                         fee_proportional_millionths: 2000000,
4197                         excess_data: Vec::new()
4198                 });
4199
4200                 // Get a route for 100 sats and check that we found the MPP route no problem and didn't
4201                 // overpay at all.
4202                 let route = get_route(&our_id, &payment_params, &network_graph, None, 100_000, 42, Arc::clone(&logger), &scorer).unwrap();
4203                 assert_eq!(route.paths.len(), 2);
4204                 // Paths are somewhat randomly ordered, but:
4205                 // * the first is channel 2 (1 msat fee) -> channel 4 -> channel 42
4206                 // * the second is channel 1 (0 fee, but 99 sat maximum) -> channel 3 -> channel 42
4207                 assert_eq!(route.paths[0][0].short_channel_id, 2);
4208                 assert_eq!(route.paths[0][0].fee_msat, 1);
4209                 assert_eq!(route.paths[0][2].fee_msat, 1_000);
4210                 assert_eq!(route.paths[1][0].short_channel_id, 1);
4211                 assert_eq!(route.paths[1][0].fee_msat, 0);
4212                 assert_eq!(route.paths[1][2].fee_msat, 99_000);
4213                 assert_eq!(route.get_total_fees(), 1);
4214                 assert_eq!(route.get_total_amount(), 100_000);
4215         }
4216
4217         #[test]
4218         fn drop_lowest_channel_mpp_route_test() {
4219                 // This test checks that low-capacity channel is dropped when after
4220                 // path finding we realize that we found more capacity than we need.
4221                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
4222                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
4223                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4224                 let payment_params = PaymentParameters::from_node_id(nodes[2]).with_features(InvoiceFeatures::known());
4225
4226                 // We need a route consisting of 3 paths:
4227                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
4228
4229                 // The first and the second paths should be sufficient, but the third should be
4230                 // cheaper, so that we select it but drop later.
4231
4232                 // First, we set limits on these (previously unlimited) channels.
4233                 // Their aggregate capacity will be 50 + 60 + 20 = 130 sats.
4234
4235                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50);
4236                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4237                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4238                         short_channel_id: 1,
4239                         timestamp: 2,
4240                         flags: 0,
4241                         cltv_expiry_delta: 0,
4242                         htlc_minimum_msat: 0,
4243                         htlc_maximum_msat: OptionalField::Present(100_000),
4244                         fee_base_msat: 0,
4245                         fee_proportional_millionths: 0,
4246                         excess_data: Vec::new()
4247                 });
4248                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
4249                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4250                         short_channel_id: 3,
4251                         timestamp: 2,
4252                         flags: 0,
4253                         cltv_expiry_delta: 0,
4254                         htlc_minimum_msat: 0,
4255                         htlc_maximum_msat: OptionalField::Present(50_000),
4256                         fee_base_msat: 100,
4257                         fee_proportional_millionths: 0,
4258                         excess_data: Vec::new()
4259                 });
4260
4261                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats (total limit 60);
4262                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4263                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4264                         short_channel_id: 12,
4265                         timestamp: 2,
4266                         flags: 0,
4267                         cltv_expiry_delta: 0,
4268                         htlc_minimum_msat: 0,
4269                         htlc_maximum_msat: OptionalField::Present(60_000),
4270                         fee_base_msat: 100,
4271                         fee_proportional_millionths: 0,
4272                         excess_data: Vec::new()
4273                 });
4274                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
4275                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4276                         short_channel_id: 13,
4277                         timestamp: 2,
4278                         flags: 0,
4279                         cltv_expiry_delta: 0,
4280                         htlc_minimum_msat: 0,
4281                         htlc_maximum_msat: OptionalField::Present(60_000),
4282                         fee_base_msat: 0,
4283                         fee_proportional_millionths: 0,
4284                         excess_data: Vec::new()
4285                 });
4286
4287                 // Path via node1 is channels {2, 4}. Limit them to 20 and 20 sats (total capacity 20 sats).
4288                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4289                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4290                         short_channel_id: 2,
4291                         timestamp: 2,
4292                         flags: 0,
4293                         cltv_expiry_delta: 0,
4294                         htlc_minimum_msat: 0,
4295                         htlc_maximum_msat: OptionalField::Present(20_000),
4296                         fee_base_msat: 0,
4297                         fee_proportional_millionths: 0,
4298                         excess_data: Vec::new()
4299                 });
4300                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
4301                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4302                         short_channel_id: 4,
4303                         timestamp: 2,
4304                         flags: 0,
4305                         cltv_expiry_delta: 0,
4306                         htlc_minimum_msat: 0,
4307                         htlc_maximum_msat: OptionalField::Present(20_000),
4308                         fee_base_msat: 0,
4309                         fee_proportional_millionths: 0,
4310                         excess_data: Vec::new()
4311                 });
4312
4313                 {
4314                         // Attempt to route more than available results in a failure.
4315                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
4316                                         &our_id, &payment_params, &network_graph, None, 150_000, 42, Arc::clone(&logger), &scorer) {
4317                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
4318                         } else { panic!(); }
4319                 }
4320
4321                 {
4322                         // Now, attempt to route 125 sats (just a bit below the capacity of 3 channels).
4323                         // Our algorithm should provide us with these 3 paths.
4324                         let route = get_route(&our_id, &payment_params, &network_graph, None, 125_000, 42, Arc::clone(&logger), &scorer).unwrap();
4325                         assert_eq!(route.paths.len(), 3);
4326                         let mut total_amount_paid_msat = 0;
4327                         for path in &route.paths {
4328                                 assert_eq!(path.len(), 2);
4329                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
4330                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
4331                         }
4332                         assert_eq!(total_amount_paid_msat, 125_000);
4333                 }
4334
4335                 {
4336                         // Attempt to route without the last small cheap channel
4337                         let route = get_route(&our_id, &payment_params, &network_graph, None, 90_000, 42, Arc::clone(&logger), &scorer).unwrap();
4338                         assert_eq!(route.paths.len(), 2);
4339                         let mut total_amount_paid_msat = 0;
4340                         for path in &route.paths {
4341                                 assert_eq!(path.len(), 2);
4342                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
4343                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
4344                         }
4345                         assert_eq!(total_amount_paid_msat, 90_000);
4346                 }
4347         }
4348
4349         #[test]
4350         fn min_criteria_consistency() {
4351                 // Test that we don't use an inconsistent metric between updating and walking nodes during
4352                 // our Dijkstra's pass. In the initial version of MPP, the "best source" for a given node
4353                 // was updated with a different criterion from the heap sorting, resulting in loops in
4354                 // calculated paths. We test for that specific case here.
4355
4356                 // We construct a network that looks like this:
4357                 //
4358                 //            node2 -1(3)2- node3
4359                 //              2          2
4360                 //               (2)     (4)
4361                 //                  1   1
4362                 //    node1 -1(5)2- node4 -1(1)2- node6
4363                 //    2
4364                 //   (6)
4365                 //        1
4366                 // our_node
4367                 //
4368                 // We create a loop on the side of our real path - our destination is node 6, with a
4369                 // previous hop of node 4. From 4, the cheapest previous path is channel 2 from node 2,
4370                 // followed by node 3 over channel 3. Thereafter, the cheapest next-hop is back to node 4
4371                 // (this time over channel 4). Channel 4 has 0 htlc_minimum_msat whereas channel 1 (the
4372                 // other channel with a previous-hop of node 4) has a high (but irrelevant to the overall
4373                 // payment) htlc_minimum_msat. In the original algorithm, this resulted in node4's
4374                 // "previous hop" being set to node 3, creating a loop in the path.
4375                 let secp_ctx = Secp256k1::new();
4376                 let logger = Arc::new(test_utils::TestLogger::new());
4377                 let network_graph = Arc::new(NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash()));
4378                 let net_graph_msg_handler = NetGraphMsgHandler::new(Arc::clone(&network_graph), None, Arc::clone(&logger));
4379                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
4380                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4381                 let payment_params = PaymentParameters::from_node_id(nodes[6]);
4382
4383                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
4384                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4385                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4386                         short_channel_id: 6,
4387                         timestamp: 1,
4388                         flags: 0,
4389                         cltv_expiry_delta: (6 << 4) | 0,
4390                         htlc_minimum_msat: 0,
4391                         htlc_maximum_msat: OptionalField::Absent,
4392                         fee_base_msat: 0,
4393                         fee_proportional_millionths: 0,
4394                         excess_data: Vec::new()
4395                 });
4396                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
4397
4398                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
4399                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
4400                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4401                         short_channel_id: 5,
4402                         timestamp: 1,
4403                         flags: 0,
4404                         cltv_expiry_delta: (5 << 4) | 0,
4405                         htlc_minimum_msat: 0,
4406                         htlc_maximum_msat: OptionalField::Absent,
4407                         fee_base_msat: 100,
4408                         fee_proportional_millionths: 0,
4409                         excess_data: Vec::new()
4410                 });
4411                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
4412
4413                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
4414                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
4415                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4416                         short_channel_id: 4,
4417                         timestamp: 1,
4418                         flags: 0,
4419                         cltv_expiry_delta: (4 << 4) | 0,
4420                         htlc_minimum_msat: 0,
4421                         htlc_maximum_msat: OptionalField::Absent,
4422                         fee_base_msat: 0,
4423                         fee_proportional_millionths: 0,
4424                         excess_data: Vec::new()
4425                 });
4426                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
4427
4428                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
4429                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
4430                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4431                         short_channel_id: 3,
4432                         timestamp: 1,
4433                         flags: 0,
4434                         cltv_expiry_delta: (3 << 4) | 0,
4435                         htlc_minimum_msat: 0,
4436                         htlc_maximum_msat: OptionalField::Absent,
4437                         fee_base_msat: 0,
4438                         fee_proportional_millionths: 0,
4439                         excess_data: Vec::new()
4440                 });
4441                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
4442
4443                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
4444                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
4445                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4446                         short_channel_id: 2,
4447                         timestamp: 1,
4448                         flags: 0,
4449                         cltv_expiry_delta: (2 << 4) | 0,
4450                         htlc_minimum_msat: 0,
4451                         htlc_maximum_msat: OptionalField::Absent,
4452                         fee_base_msat: 0,
4453                         fee_proportional_millionths: 0,
4454                         excess_data: Vec::new()
4455                 });
4456
4457                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[6], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
4458                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
4459                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4460                         short_channel_id: 1,
4461                         timestamp: 1,
4462                         flags: 0,
4463                         cltv_expiry_delta: (1 << 4) | 0,
4464                         htlc_minimum_msat: 100,
4465                         htlc_maximum_msat: OptionalField::Absent,
4466                         fee_base_msat: 0,
4467                         fee_proportional_millionths: 0,
4468                         excess_data: Vec::new()
4469                 });
4470                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[6], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
4471
4472                 {
4473                         // Now ensure the route flows simply over nodes 1 and 4 to 6.
4474                         let route = get_route(&our_id, &payment_params, &network_graph, None, 10_000, 42, Arc::clone(&logger), &scorer).unwrap();
4475                         assert_eq!(route.paths.len(), 1);
4476                         assert_eq!(route.paths[0].len(), 3);
4477
4478                         assert_eq!(route.paths[0][0].pubkey, nodes[1]);
4479                         assert_eq!(route.paths[0][0].short_channel_id, 6);
4480                         assert_eq!(route.paths[0][0].fee_msat, 100);
4481                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (5 << 4) | 0);
4482                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(1));
4483                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(6));
4484
4485                         assert_eq!(route.paths[0][1].pubkey, nodes[4]);
4486                         assert_eq!(route.paths[0][1].short_channel_id, 5);
4487                         assert_eq!(route.paths[0][1].fee_msat, 0);
4488                         assert_eq!(route.paths[0][1].cltv_expiry_delta, (1 << 4) | 0);
4489                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(4));
4490                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(5));
4491
4492                         assert_eq!(route.paths[0][2].pubkey, nodes[6]);
4493                         assert_eq!(route.paths[0][2].short_channel_id, 1);
4494                         assert_eq!(route.paths[0][2].fee_msat, 10_000);
4495                         assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
4496                         assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
4497                         assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(1));
4498                 }
4499         }
4500
4501
4502         #[test]
4503         fn exact_fee_liquidity_limit() {
4504                 // Test that if, while walking the graph, we find a hop that has exactly enough liquidity
4505                 // for us, including later hop fees, we take it. In the first version of our MPP algorithm
4506                 // we calculated fees on a higher value, resulting in us ignoring such paths.
4507                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
4508                 let (our_privkey, our_id, _, nodes) = get_nodes(&secp_ctx);
4509                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4510                 let payment_params = PaymentParameters::from_node_id(nodes[2]);
4511
4512                 // We modify the graph to set the htlc_maximum of channel 2 to below the value we wish to
4513                 // send.
4514                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4515                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4516                         short_channel_id: 2,
4517                         timestamp: 2,
4518                         flags: 0,
4519                         cltv_expiry_delta: 0,
4520                         htlc_minimum_msat: 0,
4521                         htlc_maximum_msat: OptionalField::Present(85_000),
4522                         fee_base_msat: 0,
4523                         fee_proportional_millionths: 0,
4524                         excess_data: Vec::new()
4525                 });
4526
4527                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4528                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4529                         short_channel_id: 12,
4530                         timestamp: 2,
4531                         flags: 0,
4532                         cltv_expiry_delta: (4 << 4) | 1,
4533                         htlc_minimum_msat: 0,
4534                         htlc_maximum_msat: OptionalField::Present(270_000),
4535                         fee_base_msat: 0,
4536                         fee_proportional_millionths: 1000000,
4537                         excess_data: Vec::new()
4538                 });
4539
4540                 {
4541                         // Now, attempt to route 90 sats, which is exactly 90 sats at the last hop, plus the
4542                         // 200% fee charged channel 13 in the 1-to-2 direction.
4543                         let route = get_route(&our_id, &payment_params, &network_graph, None, 90_000, 42, Arc::clone(&logger), &scorer).unwrap();
4544                         assert_eq!(route.paths.len(), 1);
4545                         assert_eq!(route.paths[0].len(), 2);
4546
4547                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
4548                         assert_eq!(route.paths[0][0].short_channel_id, 12);
4549                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
4550                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 4) | 1);
4551                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
4552                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
4553
4554                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
4555                         assert_eq!(route.paths[0][1].short_channel_id, 13);
4556                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
4557                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
4558                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
4559                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
4560                 }
4561         }
4562
4563         #[test]
4564         fn htlc_max_reduction_below_min() {
4565                 // Test that if, while walking the graph, we reduce the value being sent to meet an
4566                 // htlc_maximum_msat, we don't end up undershooting a later htlc_minimum_msat. In the
4567                 // initial version of MPP we'd accept such routes but reject them while recalculating fees,
4568                 // resulting in us thinking there is no possible path, even if other paths exist.
4569                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
4570                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
4571                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4572                 let payment_params = PaymentParameters::from_node_id(nodes[2]).with_features(InvoiceFeatures::known());
4573
4574                 // We modify the graph to set the htlc_minimum of channel 2 and 4 as needed - channel 2
4575                 // gets an htlc_maximum_msat of 80_000 and channel 4 an htlc_minimum_msat of 90_000. We
4576                 // then try to send 90_000.
4577                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4578                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4579                         short_channel_id: 2,
4580                         timestamp: 2,
4581                         flags: 0,
4582                         cltv_expiry_delta: 0,
4583                         htlc_minimum_msat: 0,
4584                         htlc_maximum_msat: OptionalField::Present(80_000),
4585                         fee_base_msat: 0,
4586                         fee_proportional_millionths: 0,
4587                         excess_data: Vec::new()
4588                 });
4589                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
4590                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4591                         short_channel_id: 4,
4592                         timestamp: 2,
4593                         flags: 0,
4594                         cltv_expiry_delta: (4 << 4) | 1,
4595                         htlc_minimum_msat: 90_000,
4596                         htlc_maximum_msat: OptionalField::Absent,
4597                         fee_base_msat: 0,
4598                         fee_proportional_millionths: 0,
4599                         excess_data: Vec::new()
4600                 });
4601
4602                 {
4603                         // Now, attempt to route 90 sats, hitting the htlc_minimum on channel 4, but
4604                         // overshooting the htlc_maximum on channel 2. Thus, we should pick the (absurdly
4605                         // expensive) channels 12-13 path.
4606                         let route = get_route(&our_id, &payment_params, &network_graph, None, 90_000, 42, Arc::clone(&logger), &scorer).unwrap();
4607                         assert_eq!(route.paths.len(), 1);
4608                         assert_eq!(route.paths[0].len(), 2);
4609
4610                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
4611                         assert_eq!(route.paths[0][0].short_channel_id, 12);
4612                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
4613                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 4) | 1);
4614                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
4615                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
4616
4617                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
4618                         assert_eq!(route.paths[0][1].short_channel_id, 13);
4619                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
4620                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
4621                         assert_eq!(route.paths[0][1].node_features.le_flags(), InvoiceFeatures::known().le_flags());
4622                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
4623                 }
4624         }
4625
4626         #[test]
4627         fn multiple_direct_first_hops() {
4628                 // Previously we'd only ever considered one first hop path per counterparty.
4629                 // However, as we don't restrict users to one channel per peer, we really need to support
4630                 // looking at all first hop paths.
4631                 // Here we test that we do not ignore all-but-the-last first hop paths per counterparty (as
4632                 // we used to do by overwriting the `first_hop_targets` hashmap entry) and that we can MPP
4633                 // route over multiple channels with the same first hop.
4634                 let secp_ctx = Secp256k1::new();
4635                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
4636                 let logger = Arc::new(test_utils::TestLogger::new());
4637                 let network_graph = NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash());
4638                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4639                 let payment_params = PaymentParameters::from_node_id(nodes[0]).with_features(InvoiceFeatures::known());
4640
4641                 {
4642                         let route = get_route(&our_id, &payment_params, &network_graph, Some(&[
4643                                 &get_channel_details(Some(3), nodes[0], InitFeatures::known(), 200_000),
4644                                 &get_channel_details(Some(2), nodes[0], InitFeatures::known(), 10_000),
4645                         ]), 100_000, 42, Arc::clone(&logger), &scorer).unwrap();
4646                         assert_eq!(route.paths.len(), 1);
4647                         assert_eq!(route.paths[0].len(), 1);
4648
4649                         assert_eq!(route.paths[0][0].pubkey, nodes[0]);
4650                         assert_eq!(route.paths[0][0].short_channel_id, 3);
4651                         assert_eq!(route.paths[0][0].fee_msat, 100_000);
4652                 }
4653                 {
4654                         let route = get_route(&our_id, &payment_params, &network_graph, Some(&[
4655                                 &get_channel_details(Some(3), nodes[0], InitFeatures::known(), 50_000),
4656                                 &get_channel_details(Some(2), nodes[0], InitFeatures::known(), 50_000),
4657                         ]), 100_000, 42, Arc::clone(&logger), &scorer).unwrap();
4658                         assert_eq!(route.paths.len(), 2);
4659                         assert_eq!(route.paths[0].len(), 1);
4660                         assert_eq!(route.paths[1].len(), 1);
4661
4662                         assert_eq!(route.paths[0][0].pubkey, nodes[0]);
4663                         assert_eq!(route.paths[0][0].short_channel_id, 3);
4664                         assert_eq!(route.paths[0][0].fee_msat, 50_000);
4665
4666                         assert_eq!(route.paths[1][0].pubkey, nodes[0]);
4667                         assert_eq!(route.paths[1][0].short_channel_id, 2);
4668                         assert_eq!(route.paths[1][0].fee_msat, 50_000);
4669                 }
4670         }
4671
4672         #[test]
4673         fn prefers_shorter_route_with_higher_fees() {
4674                 let (secp_ctx, network_graph, _, _, logger) = build_graph();
4675                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
4676                 let payment_params = PaymentParameters::from_node_id(nodes[6]).with_route_hints(last_hops(&nodes));
4677
4678                 // Without penalizing each hop 100 msats, a longer path with lower fees is chosen.
4679                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4680                 let route = get_route(
4681                         &our_id, &payment_params, &network_graph, None, 100, 42,
4682                         Arc::clone(&logger), &scorer
4683                 ).unwrap();
4684                 let path = route.paths[0].iter().map(|hop| hop.short_channel_id).collect::<Vec<_>>();
4685
4686                 assert_eq!(route.get_total_fees(), 100);
4687                 assert_eq!(route.get_total_amount(), 100);
4688                 assert_eq!(path, vec![2, 4, 6, 11, 8]);
4689
4690                 // Applying a 100 msat penalty to each hop results in taking channels 7 and 10 to nodes[6]
4691                 // from nodes[2] rather than channel 6, 11, and 8, even though the longer path is cheaper.
4692                 let scorer = test_utils::TestScorer::with_fixed_penalty(100);
4693                 let route = get_route(
4694                         &our_id, &payment_params, &network_graph, None, 100, 42,
4695                         Arc::clone(&logger), &scorer
4696                 ).unwrap();
4697                 let path = route.paths[0].iter().map(|hop| hop.short_channel_id).collect::<Vec<_>>();
4698
4699                 assert_eq!(route.get_total_fees(), 300);
4700                 assert_eq!(route.get_total_amount(), 100);
4701                 assert_eq!(path, vec![2, 4, 7, 10]);
4702         }
4703
4704         struct BadChannelScorer {
4705                 short_channel_id: u64,
4706         }
4707
4708         #[cfg(c_bindings)]
4709         impl Writeable for BadChannelScorer {
4710                 fn write<W: Writer>(&self, _w: &mut W) -> Result<(), ::io::Error> { unimplemented!() }
4711         }
4712         impl Score for BadChannelScorer {
4713                 fn channel_penalty_msat(&self, short_channel_id: u64, _send_amt: u64, _capacity_msat: u64, _source: &NodeId, _target: &NodeId) -> u64 {
4714                         if short_channel_id == self.short_channel_id { u64::max_value() } else { 0 }
4715                 }
4716
4717                 fn payment_path_failed(&mut self, _path: &[&RouteHop], _short_channel_id: u64) {}
4718                 fn payment_path_successful(&mut self, _path: &[&RouteHop]) {}
4719         }
4720
4721         struct BadNodeScorer {
4722                 node_id: NodeId,
4723         }
4724
4725         #[cfg(c_bindings)]
4726         impl Writeable for BadNodeScorer {
4727                 fn write<W: Writer>(&self, _w: &mut W) -> Result<(), ::io::Error> { unimplemented!() }
4728         }
4729
4730         impl Score for BadNodeScorer {
4731                 fn channel_penalty_msat(&self, _short_channel_id: u64, _send_amt: u64, _capacity_msat: u64, _source: &NodeId, target: &NodeId) -> u64 {
4732                         if *target == self.node_id { u64::max_value() } else { 0 }
4733                 }
4734
4735                 fn payment_path_failed(&mut self, _path: &[&RouteHop], _short_channel_id: u64) {}
4736                 fn payment_path_successful(&mut self, _path: &[&RouteHop]) {}
4737         }
4738
4739         #[test]
4740         fn avoids_routing_through_bad_channels_and_nodes() {
4741                 let (secp_ctx, network_graph, _, _, logger) = build_graph();
4742                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
4743                 let payment_params = PaymentParameters::from_node_id(nodes[6]).with_route_hints(last_hops(&nodes));
4744
4745                 // A path to nodes[6] exists when no penalties are applied to any channel.
4746                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4747                 let route = get_route(
4748                         &our_id, &payment_params, &network_graph, None, 100, 42,
4749                         Arc::clone(&logger), &scorer
4750                 ).unwrap();
4751                 let path = route.paths[0].iter().map(|hop| hop.short_channel_id).collect::<Vec<_>>();
4752
4753                 assert_eq!(route.get_total_fees(), 100);
4754                 assert_eq!(route.get_total_amount(), 100);
4755                 assert_eq!(path, vec![2, 4, 6, 11, 8]);
4756
4757                 // A different path to nodes[6] exists if channel 6 cannot be routed over.
4758                 let scorer = BadChannelScorer { short_channel_id: 6 };
4759                 let route = get_route(
4760                         &our_id, &payment_params, &network_graph, None, 100, 42,
4761                         Arc::clone(&logger), &scorer
4762                 ).unwrap();
4763                 let path = route.paths[0].iter().map(|hop| hop.short_channel_id).collect::<Vec<_>>();
4764
4765                 assert_eq!(route.get_total_fees(), 300);
4766                 assert_eq!(route.get_total_amount(), 100);
4767                 assert_eq!(path, vec![2, 4, 7, 10]);
4768
4769                 // A path to nodes[6] does not exist if nodes[2] cannot be routed through.
4770                 let scorer = BadNodeScorer { node_id: NodeId::from_pubkey(&nodes[2]) };
4771                 match get_route(
4772                         &our_id, &payment_params, &network_graph, None, 100, 42,
4773                         Arc::clone(&logger), &scorer
4774                 ) {
4775                         Err(LightningError { err, .. } ) => {
4776                                 assert_eq!(err, "Failed to find a path to the given destination");
4777                         },
4778                         Ok(_) => panic!("Expected error"),
4779                 }
4780         }
4781
4782         #[test]
4783         fn total_fees_single_path() {
4784                 let route = Route {
4785                         paths: vec![vec![
4786                                 RouteHop {
4787                                         pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
4788                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4789                                         short_channel_id: 0, fee_msat: 100, cltv_expiry_delta: 0
4790                                 },
4791                                 RouteHop {
4792                                         pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
4793                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4794                                         short_channel_id: 0, fee_msat: 150, cltv_expiry_delta: 0
4795                                 },
4796                                 RouteHop {
4797                                         pubkey: PublicKey::from_slice(&hex::decode("027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007").unwrap()[..]).unwrap(),
4798                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4799                                         short_channel_id: 0, fee_msat: 225, cltv_expiry_delta: 0
4800                                 },
4801                         ]],
4802                         payment_params: None,
4803                 };
4804
4805                 assert_eq!(route.get_total_fees(), 250);
4806                 assert_eq!(route.get_total_amount(), 225);
4807         }
4808
4809         #[test]
4810         fn total_fees_multi_path() {
4811                 let route = Route {
4812                         paths: vec![vec![
4813                                 RouteHop {
4814                                         pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
4815                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4816                                         short_channel_id: 0, fee_msat: 100, cltv_expiry_delta: 0
4817                                 },
4818                                 RouteHop {
4819                                         pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
4820                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4821                                         short_channel_id: 0, fee_msat: 150, cltv_expiry_delta: 0
4822                                 },
4823                         ],vec![
4824                                 RouteHop {
4825                                         pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
4826                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4827                                         short_channel_id: 0, fee_msat: 100, cltv_expiry_delta: 0
4828                                 },
4829                                 RouteHop {
4830                                         pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
4831                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4832                                         short_channel_id: 0, fee_msat: 150, cltv_expiry_delta: 0
4833                                 },
4834                         ]],
4835                         payment_params: None,
4836                 };
4837
4838                 assert_eq!(route.get_total_fees(), 200);
4839                 assert_eq!(route.get_total_amount(), 300);
4840         }
4841
4842         #[test]
4843         fn total_empty_route_no_panic() {
4844                 // In an earlier version of `Route::get_total_fees` and `Route::get_total_amount`, they
4845                 // would both panic if the route was completely empty. We test to ensure they return 0
4846                 // here, even though its somewhat nonsensical as a route.
4847                 let route = Route { paths: Vec::new(), payment_params: None };
4848
4849                 assert_eq!(route.get_total_fees(), 0);
4850                 assert_eq!(route.get_total_amount(), 0);
4851         }
4852
4853         #[test]
4854         fn limits_total_cltv_delta() {
4855                 let (secp_ctx, network_graph, _, _, logger) = build_graph();
4856                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
4857
4858                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4859
4860                 // Make sure that generally there is at least one route available
4861                 let feasible_max_total_cltv_delta = 1008;
4862                 let feasible_payment_params = PaymentParameters::from_node_id(nodes[6]).with_route_hints(last_hops(&nodes))
4863                         .with_max_total_cltv_expiry_delta(feasible_max_total_cltv_delta);
4864                 let route = get_route(&our_id, &feasible_payment_params, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
4865                 let path = route.paths[0].iter().map(|hop| hop.short_channel_id).collect::<Vec<_>>();
4866                 assert_ne!(path.len(), 0);
4867
4868                 // But not if we exclude all paths on the basis of their accumulated CLTV delta
4869                 let fail_max_total_cltv_delta = 23;
4870                 let fail_payment_params = PaymentParameters::from_node_id(nodes[6]).with_route_hints(last_hops(&nodes))
4871                         .with_max_total_cltv_expiry_delta(fail_max_total_cltv_delta);
4872                 match get_route(&our_id, &fail_payment_params, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer)
4873                 {
4874                         Err(LightningError { err, .. } ) => {
4875                                 assert_eq!(err, "Failed to find a path to the given destination");
4876                         },
4877                         Ok(_) => panic!("Expected error"),
4878                 }
4879         }
4880
4881         #[cfg(not(feature = "no-std"))]
4882         pub(super) fn random_init_seed() -> u64 {
4883                 // Because the default HashMap in std pulls OS randomness, we can use it as a (bad) RNG.
4884                 use core::hash::{BuildHasher, Hasher};
4885                 let seed = std::collections::hash_map::RandomState::new().build_hasher().finish();
4886                 println!("Using seed of {}", seed);
4887                 seed
4888         }
4889         #[cfg(not(feature = "no-std"))]
4890         use util::ser::Readable;
4891
4892         #[test]
4893         #[cfg(not(feature = "no-std"))]
4894         fn generate_routes() {
4895                 let mut d = match super::test_utils::get_route_file() {
4896                         Ok(f) => f,
4897                         Err(e) => {
4898                                 eprintln!("{}", e);
4899                                 return;
4900                         },
4901                 };
4902                 let graph = NetworkGraph::read(&mut d).unwrap();
4903                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4904
4905                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
4906                 let mut seed = random_init_seed() as usize;
4907                 let nodes = graph.read_only().nodes().clone();
4908                 'load_endpoints: for _ in 0..10 {
4909                         loop {
4910                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4911                                 let src = &PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4912                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4913                                 let dst = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4914                                 let payment_params = PaymentParameters::from_node_id(dst);
4915                                 let amt = seed as u64 % 200_000_000;
4916                                 if get_route(src, &payment_params, &graph, None, amt, 42, &test_utils::TestLogger::new(), &scorer).is_ok() {
4917                                         continue 'load_endpoints;
4918                                 }
4919                         }
4920                 }
4921         }
4922
4923         #[test]
4924         #[cfg(not(feature = "no-std"))]
4925         fn generate_routes_mpp() {
4926                 let mut d = match super::test_utils::get_route_file() {
4927                         Ok(f) => f,
4928                         Err(e) => {
4929                                 eprintln!("{}", e);
4930                                 return;
4931                         },
4932                 };
4933                 let graph = NetworkGraph::read(&mut d).unwrap();
4934                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4935
4936                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
4937                 let mut seed = random_init_seed() as usize;
4938                 let nodes = graph.read_only().nodes().clone();
4939                 'load_endpoints: for _ in 0..10 {
4940                         loop {
4941                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4942                                 let src = &PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4943                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4944                                 let dst = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4945                                 let payment_params = PaymentParameters::from_node_id(dst).with_features(InvoiceFeatures::known());
4946                                 let amt = seed as u64 % 200_000_000;
4947                                 if get_route(src, &payment_params, &graph, None, amt, 42, &test_utils::TestLogger::new(), &scorer).is_ok() {
4948                                         continue 'load_endpoints;
4949                                 }
4950                         }
4951                 }
4952         }
4953 }
4954
4955 #[cfg(all(test, not(feature = "no-std")))]
4956 pub(crate) mod test_utils {
4957         use std::fs::File;
4958         /// Tries to open a network graph file, or panics with a URL to fetch it.
4959         pub(crate) fn get_route_file() -> Result<std::fs::File, &'static str> {
4960                 let res = File::open("net_graph-2021-05-31.bin") // By default we're run in RL/lightning
4961                         .or_else(|_| File::open("lightning/net_graph-2021-05-31.bin")) // We may be run manually in RL/
4962                         .or_else(|_| { // Fall back to guessing based on the binary location
4963                                 // path is likely something like .../rust-lightning/target/debug/deps/lightning-...
4964                                 let mut path = std::env::current_exe().unwrap();
4965                                 path.pop(); // lightning-...
4966                                 path.pop(); // deps
4967                                 path.pop(); // debug
4968                                 path.pop(); // target
4969                                 path.push("lightning");
4970                                 path.push("net_graph-2021-05-31.bin");
4971                                 eprintln!("{}", path.to_str().unwrap());
4972                                 File::open(path)
4973                         })
4974                 .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");
4975                 #[cfg(require_route_graph_test)]
4976                 return Ok(res.unwrap());
4977                 #[cfg(not(require_route_graph_test))]
4978                 return res;
4979         }
4980 }
4981
4982 #[cfg(all(test, feature = "unstable", not(feature = "no-std")))]
4983 mod benches {
4984         use super::*;
4985         use bitcoin::hashes::Hash;
4986         use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
4987         use chain::transaction::OutPoint;
4988         use ln::channelmanager::{ChannelCounterparty, ChannelDetails};
4989         use ln::features::{InitFeatures, InvoiceFeatures};
4990         use routing::scoring::Scorer;
4991         use util::logger::{Logger, Record};
4992
4993         use test::Bencher;
4994
4995         struct DummyLogger {}
4996         impl Logger for DummyLogger {
4997                 fn log(&self, _record: &Record) {}
4998         }
4999
5000         struct ZeroPenaltyScorer;
5001         impl Score for ZeroPenaltyScorer {
5002                 fn channel_penalty_msat(
5003                         &self, _short_channel_id: u64, _send_amt: u64, _capacity_msat: u64, _source: &NodeId, _target: &NodeId
5004                 ) -> u64 { 0 }
5005                 fn payment_path_failed(&mut self, _path: &[&RouteHop], _short_channel_id: u64) {}
5006                 fn payment_path_successful(&mut self, _path: &[&RouteHop]) {}
5007         }
5008
5009         fn read_network_graph() -> NetworkGraph {
5010                 let mut d = test_utils::get_route_file().unwrap();
5011                 NetworkGraph::read(&mut d).unwrap()
5012         }
5013
5014         fn payer_pubkey() -> PublicKey {
5015                 let secp_ctx = Secp256k1::new();
5016                 PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap())
5017         }
5018
5019         #[inline]
5020         fn first_hop(node_id: PublicKey) -> ChannelDetails {
5021                 ChannelDetails {
5022                         channel_id: [0; 32],
5023                         counterparty: ChannelCounterparty {
5024                                 features: InitFeatures::known(),
5025                                 node_id,
5026                                 unspendable_punishment_reserve: 0,
5027                                 forwarding_info: None,
5028                         },
5029                         funding_txo: Some(OutPoint {
5030                                 txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0
5031                         }),
5032                         short_channel_id: Some(1),
5033                         channel_value_satoshis: 10_000_000,
5034                         user_channel_id: 0,
5035                         balance_msat: 10_000_000,
5036                         outbound_capacity_msat: 10_000_000,
5037                         inbound_capacity_msat: 0,
5038                         unspendable_punishment_reserve: None,
5039                         confirmations_required: None,
5040                         force_close_spend_delay: None,
5041                         is_outbound: true,
5042                         is_funding_locked: true,
5043                         is_usable: true,
5044                         is_public: true,
5045                 }
5046         }
5047
5048         #[bench]
5049         fn generate_routes_with_zero_penalty_scorer(bench: &mut Bencher) {
5050                 let network_graph = read_network_graph();
5051                 let scorer = ZeroPenaltyScorer;
5052                 generate_routes(bench, &network_graph, scorer, InvoiceFeatures::empty());
5053         }
5054
5055         #[bench]
5056         fn generate_mpp_routes_with_zero_penalty_scorer(bench: &mut Bencher) {
5057                 let network_graph = read_network_graph();
5058                 let scorer = ZeroPenaltyScorer;
5059                 generate_routes(bench, &network_graph, scorer, InvoiceFeatures::known());
5060         }
5061
5062         #[bench]
5063         fn generate_routes_with_default_scorer(bench: &mut Bencher) {
5064                 let network_graph = read_network_graph();
5065                 let scorer = Scorer::default();
5066                 generate_routes(bench, &network_graph, scorer, InvoiceFeatures::empty());
5067         }
5068
5069         #[bench]
5070         fn generate_mpp_routes_with_default_scorer(bench: &mut Bencher) {
5071                 let network_graph = read_network_graph();
5072                 let scorer = Scorer::default();
5073                 generate_routes(bench, &network_graph, scorer, InvoiceFeatures::known());
5074         }
5075
5076         fn generate_routes<S: Score>(
5077                 bench: &mut Bencher, graph: &NetworkGraph, mut scorer: S, features: InvoiceFeatures
5078         ) {
5079                 let nodes = graph.read_only().nodes().clone();
5080                 let payer = payer_pubkey();
5081
5082                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
5083                 let mut routes = Vec::new();
5084                 let mut route_endpoints = Vec::new();
5085                 let mut seed: usize = 0xdeadbeef;
5086                 'load_endpoints: for _ in 0..100 {
5087                         loop {
5088                                 seed *= 0xdeadbeef;
5089                                 let src = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
5090                                 seed *= 0xdeadbeef;
5091                                 let dst = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
5092                                 let params = PaymentParameters::from_node_id(dst).with_features(features.clone());
5093                                 let first_hop = first_hop(src);
5094                                 let amt = seed as u64 % 1_000_000;
5095                                 if let Ok(route) = get_route(&payer, &params, &graph, Some(&[&first_hop]), amt, 42, &DummyLogger{}, &scorer) {
5096                                         routes.push(route);
5097                                         route_endpoints.push((first_hop, params, amt));
5098                                         continue 'load_endpoints;
5099                                 }
5100                         }
5101                 }
5102
5103                 // ...and seed the scorer with success and failure data...
5104                 for route in routes {
5105                         let amount = route.get_total_amount();
5106                         if amount < 250_000 {
5107                                 for path in route.paths {
5108                                         scorer.payment_path_successful(&path.iter().collect::<Vec<_>>());
5109                                 }
5110                         } else if amount > 750_000 {
5111                                 for path in route.paths {
5112                                         let short_channel_id = path[path.len() / 2].short_channel_id;
5113                                         scorer.payment_path_failed(&path.iter().collect::<Vec<_>>(), short_channel_id);
5114                                 }
5115                         }
5116                 }
5117
5118                 // ...then benchmark finding paths between the nodes we learned.
5119                 let mut idx = 0;
5120                 bench.iter(|| {
5121                         let (first_hop, params, amt) = &route_endpoints[idx % route_endpoints.len()];
5122                         assert!(get_route(&payer, params, &graph, Some(&[first_hop]), *amt, 42, &DummyLogger{}, &scorer).is_ok());
5123                         idx += 1;
5124                 });
5125         }
5126 }