_ 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::{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 struct DummyDirectionalChannelInfo {
 348         cltv_expiry_delta: u32,
 349         htlc_minimum_msat: u64,
 350         htlc_maximum_msat: Option<u64>,
 351         fees: RoutingFees,
 352 }
 353
 354 /// It's useful to keep track of the hops associated with the fees required to use them,
 355 /// so that we can choose cheaper paths (as per Dijkstra's algorithm).
 356 /// Fee values should be updated only in the context of the whole path, see update_value_and_recompute_fees.
 357 /// These fee values are useful to choose hops as we traverse the graph "payee-to-payer".
 358 #[derive(Clone, Debug)]
 359 struct PathBuildingHop<'a> {
 360         // The RouteHintHop fields which will eventually be used if this hop is used in a final Route.
 361         // Note that node_features is calculated separately after our initial graph walk.
 362         node_id: NodeId,
 363         short_channel_id: u64,
 364         channel_features: &'a ChannelFeatures,
 365         fee_msat: u64,
 366         cltv_expiry_delta: u32,
 367
 368         /// Minimal fees required to route to the source node of the current hop via any of its inbound channels.
 369         src_lowest_inbound_fees: RoutingFees,
 370         /// Fees of the channel used in this hop.
 371         channel_fees: RoutingFees,
 372         /// All the fees paid *after* this channel on the way to the destination
 373         next_hops_fee_msat: u64,
 374         /// Fee paid for the use of the current channel (see channel_fees).
 375         /// The value will be actually deducted from the counterparty balance on the previous link.
 376         hop_use_fee_msat: u64,
 377         /// Used to compare channels when choosing the for routing.
 378         /// Includes paying for the use of a hop and the following hops, as well as
 379         /// an estimated cost of reaching this hop.
 380         /// Might get stale when fees are recomputed. Primarily for internal use.
 381         total_fee_msat: u64,
 382         /// This is useful for update_value_and_recompute_fees to make sure
 383         /// we don't fall below the minimum. Should not be updated manually and
 384         /// generally should not be accessed.
 385         htlc_minimum_msat: u64,
 386         /// A mirror of the same field in RouteGraphNode. Note that this is only used during the graph
 387         /// walk and may be invalid thereafter.
 388         path_htlc_minimum_msat: u64,
 389         /// All penalties incurred from this channel on the way to the destination, as calculated using
 390         /// channel scoring.
 391         path_penalty_msat: u64,
 392         /// If we've already processed a node as the best node, we shouldn't process it again. Normally
 393         /// we'd just ignore it if we did as all channels would have a higher new fee, but because we
 394         /// may decrease the amounts in use as we walk the graph, the actual calculated fee may
 395         /// decrease as well. Thus, we have to explicitly track which nodes have been processed and
 396         /// avoid processing them again.
 397         was_processed: bool,
 398         #[cfg(any(test, feature = "fuzztarget"))]
 399         // In tests, we apply further sanity checks on cases where we skip nodes we already processed
 400         // to ensure it is specifically in cases where the fee has gone down because of a decrease in
 401         // value_contribution_msat, which requires tracking it here. See comments below where it is
 402         // used for more info.
 403         value_contribution_msat: u64,
 404 }
 405
 406 // Instantiated with a list of hops with correct data in them collected during path finding,
 407 // an instance of this struct should be further modified only via given methods.
 408 #[derive(Clone)]
 409 struct PaymentPath<'a> {
 410         hops: Vec<(PathBuildingHop<'a>, NodeFeatures)>,
 411 }
 412
 413 impl<'a> PaymentPath<'a> {
 414         // TODO: Add a value_msat field to PaymentPath and use it instead of this function.
 415         fn get_value_msat(&self) -> u64 {
 416                 self.hops.last().unwrap().0.fee_msat
 417         }
 418
 419         fn get_total_fee_paid_msat(&self) -> u64 {
 420                 if self.hops.len() < 1 {
 421                         return 0;
 422                 }
 423                 let mut result = 0;
 424                 // Can't use next_hops_fee_msat because it gets outdated.
 425                 for (i, (hop, _)) in self.hops.iter().enumerate() {
 426                         if i != self.hops.len() - 1 {
 427                                 result += hop.fee_msat;
 428                         }
 429                 }
 430                 return result;
 431         }
 432
 433         // If the amount transferred by the path is updated, the fees should be adjusted. Any other way
 434         // to change fees may result in an inconsistency.
 435         //
 436         // Sometimes we call this function right after constructing a path which is inconsistent in
 437         // that it the value being transferred has decreased while we were doing path finding, leading
 438         // to the fees being paid not lining up with the actual limits.
 439         //
 440         // Note that this function is not aware of the available_liquidity limit, and thus does not
 441         // support increasing the value being transferred.
 442         fn update_value_and_recompute_fees(&mut self, value_msat: u64) {
 443                 assert!(value_msat <= self.hops.last().unwrap().0.fee_msat);
 444
 445                 let mut total_fee_paid_msat = 0 as u64;
 446                 for i in (0..self.hops.len()).rev() {
 447                         let last_hop = i == self.hops.len() - 1;
 448
 449                         // For non-last-hop, this value will represent the fees paid on the current hop. It
 450                         // will consist of the fees for the use of the next hop, and extra fees to match
 451                         // htlc_minimum_msat of the current channel. Last hop is handled separately.
 452                         let mut cur_hop_fees_msat = 0;
 453                         if !last_hop {
 454                                 cur_hop_fees_msat = self.hops.get(i + 1).unwrap().0.hop_use_fee_msat;
 455                         }
 456
 457                         let mut cur_hop = &mut self.hops.get_mut(i).unwrap().0;
 458                         cur_hop.next_hops_fee_msat = total_fee_paid_msat;
 459                         // Overpay in fees if we can't save these funds due to htlc_minimum_msat.
 460                         // We try to account for htlc_minimum_msat in scoring (add_entry!), so that nodes don't
 461                         // set it too high just to maliciously take more fees by exploiting this
 462                         // match htlc_minimum_msat logic.
 463                         let mut cur_hop_transferred_amount_msat = total_fee_paid_msat + value_msat;
 464                         if let Some(extra_fees_msat) = cur_hop.htlc_minimum_msat.checked_sub(cur_hop_transferred_amount_msat) {
 465                                 // Note that there is a risk that *previous hops* (those closer to us, as we go
 466                                 // payee->our_node here) would exceed their htlc_maximum_msat or available balance.
 467                                 //
 468                                 // This might make us end up with a broken route, although this should be super-rare
 469                                 // in practice, both because of how healthy channels look like, and how we pick
 470                                 // channels in add_entry.
 471                                 // Also, this can't be exploited more heavily than *announce a free path and fail
 472                                 // all payments*.
 473                                 cur_hop_transferred_amount_msat += extra_fees_msat;
 474                                 total_fee_paid_msat += extra_fees_msat;
 475                                 cur_hop_fees_msat += extra_fees_msat;
 476                         }
 477
 478                         if last_hop {
 479                                 // Final hop is a special case: it usually has just value_msat (by design), but also
 480                                 // it still could overpay for the htlc_minimum_msat.
 481                                 cur_hop.fee_msat = cur_hop_transferred_amount_msat;
 482                         } else {
 483                                 // Propagate updated fees for the use of the channels to one hop back, where they
 484                                 // will be actually paid (fee_msat). The last hop is handled above separately.
 485                                 cur_hop.fee_msat = cur_hop_fees_msat;
 486                         }
 487
 488                         // Fee for the use of the current hop which will be deducted on the previous hop.
 489                         // Irrelevant for the first hop, as it doesn't have the previous hop, and the use of
 490                         // this channel is free for us.
 491                         if i != 0 {
 492                                 if let Some(new_fee) = compute_fees(cur_hop_transferred_amount_msat, cur_hop.channel_fees) {
 493                                         cur_hop.hop_use_fee_msat = new_fee;
 494                                         total_fee_paid_msat += new_fee;
 495                                 } else {
 496                                         // It should not be possible because this function is called only to reduce the
 497                                         // value. In that case, compute_fee was already called with the same fees for
 498                                         // larger amount and there was no overflow.
 499                                         unreachable!();
 500                                 }
 501                         }
 502                 }
 503         }
 504 }
 505
 506 fn compute_fees(amount_msat: u64, channel_fees: RoutingFees) -> Option<u64> {
 507         let proportional_fee_millions =
 508                 amount_msat.checked_mul(channel_fees.proportional_millionths as u64);
 509         if let Some(new_fee) = proportional_fee_millions.and_then(|part| {
 510                         (channel_fees.base_msat as u64).checked_add(part / 1_000_000) }) {
 511
 512                 Some(new_fee)
 513         } else {
 514                 // This function may be (indirectly) called without any verification,
 515                 // with channel_fees provided by a caller. We should handle it gracefully.
 516                 None
 517         }
 518 }
 519
 520 /// Finds a route from us (payer) to the given target node (payee).
 521 ///
 522 /// If the payee provided features in their invoice, they should be provided via `params.payee`.
 523 /// Without this, MPP will only be used if the payee's features are available in the network graph.
 524 ///
 525 /// Private routing paths between a public node and the target may be included in `params.payee`.
 526 ///
 527 /// If some channels aren't announced, it may be useful to fill in `first_hops` with the results
 528 /// from [`ChannelManager::list_usable_channels`]. If it is filled in, the view of our local
 529 /// channels from [`NetworkGraph`] will be ignored, and only those in `first_hops` will be used.
 530 ///
 531 /// The fees on channels from us to the next hop are ignored as they are assumed to all be equal.
 532 /// However, the enabled/disabled bit on such channels as well as the `htlc_minimum_msat` /
 533 /// `htlc_maximum_msat` *are* checked as they may change based on the receiving node.
 534 ///
 535 /// # Note
 536 ///
 537 /// May be used to re-compute a [`Route`] when handling a [`Event::PaymentPathFailed`]. Any
 538 /// adjustments to the [`NetworkGraph`] and channel scores should be made prior to calling this
 539 /// function.
 540 ///
 541 /// # Panics
 542 ///
 543 /// Panics if first_hops contains channels without short_channel_ids;
 544 /// [`ChannelManager::list_usable_channels`] will never include such channels.
 545 ///
 546 /// [`ChannelManager::list_usable_channels`]: crate::ln::channelmanager::ChannelManager::list_usable_channels
 547 /// [`Event::PaymentPathFailed`]: crate::util::events::Event::PaymentPathFailed
 548 pub fn find_route<L: Deref, S: Score>(
 549         our_node_pubkey: &PublicKey, route_params: &RouteParameters, network: &NetworkGraph,
 550         first_hops: Option<&[&ChannelDetails]>, logger: L, scorer: &S
 551 ) -> Result<Route, LightningError>
 552 where L::Target: Logger {
 553         get_route(
 554                 our_node_pubkey, &route_params.payment_params, network, first_hops, route_params.final_value_msat,
 555                 route_params.final_cltv_expiry_delta, logger, scorer
 556         )
 557 }
 558
 559 pub(crate) fn get_route<L: Deref, S: Score>(
 560         our_node_pubkey: &PublicKey, payment_params: &PaymentParameters, network: &NetworkGraph,
 561         first_hops: Option<&[&ChannelDetails]>, final_value_msat: u64, final_cltv_expiry_delta: u32,
 562         logger: L, scorer: &S
 563 ) -> Result<Route, LightningError>
 564 where L::Target: Logger {
 565         let payee_node_id = NodeId::from_pubkey(&payment_params.payee_pubkey);
 566         let our_node_id = NodeId::from_pubkey(&our_node_pubkey);
 567
 568         if payee_node_id == our_node_id {
 569                 return Err(LightningError{err: "Cannot generate a route to ourselves".to_owned(), action: ErrorAction::IgnoreError});
 570         }
 571
 572         if final_value_msat > MAX_VALUE_MSAT {
 573                 return Err(LightningError{err: "Cannot generate a route of more value than all existing satoshis".to_owned(), action: ErrorAction::IgnoreError});
 574         }
 575
 576         if final_value_msat == 0 {
 577                 return Err(LightningError{err: "Cannot send a payment of 0 msat".to_owned(), action: ErrorAction::IgnoreError});
 578         }
 579
 580         for route in payment_params.route_hints.iter() {
 581                 for hop in &route.0 {
 582                         if hop.src_node_id == payment_params.payee_pubkey {
 583                                 return Err(LightningError{err: "Route hint cannot have the payee as the source.".to_owned(), action: ErrorAction::IgnoreError});
 584                         }
 585                 }
 586         }
 587
 588         // The general routing idea is the following:
 589         // 1. Fill first/last hops communicated by the caller.
 590         // 2. Attempt to construct a path from payer to payee for transferring
 591         //    any ~sufficient (described later) value.
 592         //    If succeed, remember which channels were used and how much liquidity they have available,
 593         //    so that future paths don't rely on the same liquidity.
 594         // 3. Proceed to the next step if:
 595         //    - we hit the recommended target value;
 596         //    - OR if we could not construct a new path. Any next attempt will fail too.
 597         //    Otherwise, repeat step 2.
 598         // 4. See if we managed to collect paths which aggregately are able to transfer target value
 599         //    (not recommended value). If yes, proceed. If not, fail routing.
 600         // 5. Randomly combine paths into routes having enough to fulfill the payment. (TODO: knapsack)
 601         // 6. Of all the found paths, select only those with the lowest total fee.
 602         // 7. The last path in every selected route is likely to be more than we need.
 603         //    Reduce its value-to-transfer and recompute fees.
 604         // 8. Choose the best route by the lowest total fee.
 605
 606         // As for the actual search algorithm,
 607         // we do a payee-to-payer pseudo-Dijkstra's sorting by each node's distance from the payee
 608         // plus the minimum per-HTLC fee to get from it to another node (aka "shitty pseudo-A*").
 609         //
 610         // We are not a faithful Dijkstra's implementation because we can change values which impact
 611         // earlier nodes while processing later nodes. Specifically, if we reach a channel with a lower
 612         // liquidity limit (via htlc_maximum_msat, on-chain capacity or assumed liquidity limits) than
 613         // the value we are currently attempting to send over a path, we simply reduce the value being
 614         // sent along the path for any hops after that channel. This may imply that later fees (which
 615         // we've already tabulated) are lower because a smaller value is passing through the channels
 616         // (and the proportional fee is thus lower). There isn't a trivial way to recalculate the
 617         // channels which were selected earlier (and which may still be used for other paths without a
 618         // lower liquidity limit), so we simply accept that some liquidity-limited paths may be
 619         // de-preferenced.
 620         //
 621         // One potentially problematic case for this algorithm would be if there are many
 622         // liquidity-limited paths which are liquidity-limited near the destination (ie early in our
 623         // graph walking), we may never find a path which is not liquidity-limited and has lower
 624         // proportional fee (and only lower absolute fee when considering the ultimate value sent).
 625         // Because we only consider paths with at least 5% of the total value being sent, the damage
 626         // from such a case should be limited, however this could be further reduced in the future by
 627         // calculating fees on the amount we wish to route over a path, ie ignoring the liquidity
 628         // limits for the purposes of fee calculation.
 629         //
 630         // Alternatively, we could store more detailed path information in the heap (targets, below)
 631         // and index the best-path map (dist, below) by node *and* HTLC limits, however that would blow
 632         // up the runtime significantly both algorithmically (as we'd traverse nodes multiple times)
 633         // and practically (as we would need to store dynamically-allocated path information in heap
 634         // objects, increasing malloc traffic and indirect memory access significantly). Further, the
 635         // results of such an algorithm would likely be biased towards lower-value paths.
 636         //
 637         // Further, we could return to a faithful Dijkstra's algorithm by rejecting paths with limits
 638         // outside of our current search value, running a path search more times to gather candidate
 639         // paths at different values. While this may be acceptable, further path searches may increase
 640         // runtime for little gain. Specifically, the current algorithm rather efficiently explores the
 641         // graph for candidate paths, calculating the maximum value which can realistically be sent at
 642         // the same time, remaining generic across different payment values.
 643         //
 644         // TODO: There are a few tweaks we could do, including possibly pre-calculating more stuff
 645         // to use as the A* heuristic beyond just the cost to get one node further than the current
 646         // one.
 647
 648         let network_graph = network.read_only();
 649         let network_channels = network_graph.channels();
 650         let network_nodes = network_graph.nodes();
 651         let dummy_directional_info = DummyDirectionalChannelInfo { // used for first_hops routes
 652                 cltv_expiry_delta: 0,
 653                 htlc_minimum_msat: 0,
 654                 htlc_maximum_msat: None,
 655                 fees: RoutingFees {
 656                         base_msat: 0,
 657                         proportional_millionths: 0,
 658                 }
 659         };
 660
 661         // Allow MPP only if we have a features set from somewhere that indicates the payee supports
 662         // it. If the payee supports it they're supposed to include it in the invoice, so that should
 663         // work reliably.
 664         let allow_mpp = if let Some(features) = &payment_params.features {
 665                 features.supports_basic_mpp()
 666         } else if let Some(node) = network_nodes.get(&payee_node_id) {
 667                 if let Some(node_info) = node.announcement_info.as_ref() {
 668                         node_info.features.supports_basic_mpp()
 669                 } else { false }
 670         } else { false };
 671         log_trace!(logger, "Searching for a route from payer {} to payee {} {} MPP", our_node_pubkey,
 672                 payment_params.payee_pubkey, if allow_mpp { "with" } else { "without" });
 673
 674         // Step (1).
 675         // Prepare the data we'll use for payee-to-payer search by
 676         // inserting first hops suggested by the caller as targets.
 677         // Our search will then attempt to reach them while traversing from the payee node.
 678         let mut first_hop_targets: HashMap<_, Vec<(_, ChannelFeatures, _, NodeFeatures)>> =
 679                 HashMap::with_capacity(if first_hops.is_some() { first_hops.as_ref().unwrap().len() } else { 0 });
 680         if let Some(hops) = first_hops {
 681                 for chan in hops {
 682                         let short_channel_id = chan.short_channel_id.expect("first_hops should be filled in with usable channels, not pending ones");
 683                         if chan.counterparty.node_id == *our_node_pubkey {
 684                                 return Err(LightningError{err: "First hop cannot have our_node_pubkey as a destination.".to_owned(), action: ErrorAction::IgnoreError});
 685                         }
 686                         first_hop_targets.entry(NodeId::from_pubkey(&chan.counterparty.node_id)).or_insert(Vec::new())
 687                                 .push((short_channel_id, chan.counterparty.features.to_context(), chan.outbound_capacity_msat, chan.counterparty.features.to_context()));
 688                 }
 689                 if first_hop_targets.is_empty() {
 690                         return Err(LightningError{err: "Cannot route when there are no outbound routes away from us".to_owned(), action: ErrorAction::IgnoreError});
 691                 }
 692         }
 693
 694         let empty_channel_features = ChannelFeatures::empty();
 695
 696         // The main heap containing all candidate next-hops sorted by their score (max(A* fee,
 697         // htlc_minimum)). Ideally this would be a heap which allowed cheap score reduction instead of
 698         // adding duplicate entries when we find a better path to a given node.
 699         let mut targets = BinaryHeap::new();
 700
 701         // Map from node_id to information about the best current path to that node, including feerate
 702         // information.
 703         let mut dist = HashMap::with_capacity(network_nodes.len());
 704
 705         // During routing, if we ignore a path due to an htlc_minimum_msat limit, we set this,
 706         // indicating that we may wish to try again with a higher value, potentially paying to meet an
 707         // htlc_minimum with extra fees while still finding a cheaper path.
 708         let mut hit_minimum_limit;
 709
 710         // When arranging a route, we select multiple paths so that we can make a multi-path payment.
 711         // We start with a path_value of the exact amount we want, and if that generates a route we may
 712         // return it immediately. Otherwise, we don't stop searching for paths until we have 3x the
 713         // amount we want in total across paths, selecting the best subset at the end.
 714         const ROUTE_CAPACITY_PROVISION_FACTOR: u64 = 3;
 715         let recommended_value_msat = final_value_msat * ROUTE_CAPACITY_PROVISION_FACTOR as u64;
 716         let mut path_value_msat = final_value_msat;
 717
 718         // We don't want multiple paths (as per MPP) share liquidity of the same channels.
 719         // This map allows paths to be aware of the channel use by other paths in the same call.
 720         // This would help to make a better path finding decisions and not "overbook" channels.
 721         // It is unaware of the directions (except for `outbound_capacity_msat` in `first_hops`).
 722         let mut bookkept_channels_liquidity_available_msat = HashMap::with_capacity(network_nodes.len());
 723
 724         // Keeping track of how much value we already collected across other paths. Helps to decide:
 725         // - how much a new path should be transferring (upper bound);
 726         // - whether a channel should be disregarded because
 727         //   it's available liquidity is too small comparing to how much more we need to collect;
 728         // - when we want to stop looking for new paths.
 729         let mut already_collected_value_msat = 0;
 730
 731         log_trace!(logger, "Building path from {} (payee) to {} (us/payer) for value {} msat.", payment_params.payee_pubkey, our_node_pubkey, final_value_msat);
 732
 733         macro_rules! add_entry {
 734                 // Adds entry which goes from $src_node_id to $dest_node_id
 735                 // over the channel with id $chan_id with fees described in
 736                 // $directional_info.
 737                 // $next_hops_fee_msat represents the fees paid for using all the channels *after* this one,
 738                 // since that value has to be transferred over this channel.
 739                 // Returns whether this channel caused an update to `targets`.
 740                 ( $chan_id: expr, $src_node_id: expr, $dest_node_id: expr, $directional_info: expr, $capacity_sats: expr, $chan_features: expr, $next_hops_fee_msat: expr,
 741                    $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr, $next_hops_path_penalty_msat: expr, $next_hops_cltv_delta: expr ) => { {
 742                         // We "return" whether we updated the path at the end, via this:
 743                         let mut did_add_update_path_to_src_node = false;
 744                         // Channels to self should not be used. This is more of belt-and-suspenders, because in
 745                         // practice these cases should be caught earlier:
 746                         // - for regular channels at channel announcement (TODO)
 747                         // - for first and last hops early in get_route
 748                         if $src_node_id != $dest_node_id.clone() {
 749                                 let available_liquidity_msat = bookkept_channels_liquidity_available_msat.entry($chan_id.clone()).or_insert_with(|| {
 750                                         let mut initial_liquidity_available_msat = None;
 751                                         if let Some(capacity_sats) = $capacity_sats {
 752                                                 initial_liquidity_available_msat = Some(capacity_sats * 1000);
 753                                         }
 754
 755                                         if let Some(htlc_maximum_msat) = $directional_info.htlc_maximum_msat {
 756                                                 if let Some(available_msat) = initial_liquidity_available_msat {
 757                                                         initial_liquidity_available_msat = Some(cmp::min(available_msat, htlc_maximum_msat));
 758                                                 } else {
 759                                                         initial_liquidity_available_msat = Some(htlc_maximum_msat);
 760                                                 }
 761                                         }
 762
 763                                         match initial_liquidity_available_msat {
 764                                                 Some(available_msat) => available_msat,
 765                                                 // We assume channels with unknown balance have
 766                                                 // a capacity of 0.0025 BTC (or 250_000 sats).
 767                                                 None => 250_000 * 1000
 768                                         }
 769                                 });
 770
 771                                 // It is tricky to substract $next_hops_fee_msat from available liquidity here.
 772                                 // It may be misleading because we might later choose to reduce the value transferred
 773                                 // over these channels, and the channel which was insufficient might become sufficient.
 774                                 // Worst case: we drop a good channel here because it can't cover the high following
 775                                 // fees caused by one expensive channel, but then this channel could have been used
 776                                 // if the amount being transferred over this path is lower.
 777                                 // We do this for now, but this is a subject for removal.
 778                                 if let Some(available_value_contribution_msat) = available_liquidity_msat.checked_sub($next_hops_fee_msat) {
 779
 780                                         // Routing Fragmentation Mitigation heuristic:
 781                                         //
 782                                         // Routing fragmentation across many payment paths increases the overall routing
 783                                         // fees as you have irreducible routing fees per-link used (`fee_base_msat`).
 784                                         // Taking too many smaller paths also increases the chance of payment failure.
 785                                         // Thus to avoid this effect, we require from our collected links to provide
 786                                         // at least a minimal contribution to the recommended value yet-to-be-fulfilled.
 787                                         //
 788                                         // This requirement is currently 5% of the remaining-to-be-collected value.
 789                                         // This means as we successfully advance in our collection,
 790                                         // the absolute liquidity contribution is lowered,
 791                                         // thus increasing the number of potential channels to be selected.
 792
 793                                         // Derive the minimal liquidity contribution with a ratio of 20 (5%, rounded up)
 794                                         // or 100% if we're not allowed to do multipath payments.
 795                                         let minimal_value_contribution_msat: u64 = if allow_mpp {
 796                                                 (recommended_value_msat - already_collected_value_msat + 19) / 20
 797                                         } else {
 798                                                 final_value_msat
 799                                         };
 800                                         // Verify the liquidity offered by this channel complies to the minimal contribution.
 801                                         let contributes_sufficient_value = available_value_contribution_msat >= minimal_value_contribution_msat;
 802
 803
 804                                         // Do not consider candidates that exceed the maximum total cltv expiry limit.
 805                                         let max_total_cltv_expiry_delta = payment_params.max_total_cltv_expiry_delta;
 806                                         let hop_total_cltv_delta = ($next_hops_cltv_delta as u32)
 807                                                 .checked_add($directional_info.cltv_expiry_delta as u32)
 808                                                 .unwrap_or(u32::max_value());
 809                                         let doesnt_exceed_cltv_delta_limit = hop_total_cltv_delta <= max_total_cltv_expiry_delta;
 810
 811                                         let value_contribution_msat = cmp::min(available_value_contribution_msat, $next_hops_value_contribution);
 812                                         // Includes paying fees for the use of the following channels.
 813                                         let amount_to_transfer_over_msat: u64 = match value_contribution_msat.checked_add($next_hops_fee_msat) {
 814                                                 Some(result) => result,
 815                                                 // Can't overflow due to how the values were computed right above.
 816                                                 None => unreachable!(),
 817                                         };
 818                                         #[allow(unused_comparisons)] // $next_hops_path_htlc_minimum_msat is 0 in some calls so rustc complains
 819                                         let over_path_minimum_msat = amount_to_transfer_over_msat >= $directional_info.htlc_minimum_msat &&
 820                                                 amount_to_transfer_over_msat >= $next_hops_path_htlc_minimum_msat;
 821
 822                                         // If HTLC minimum is larger than the amount we're going to transfer, we shouldn't
 823                                         // bother considering this channel.
 824                                         // Since we're choosing amount_to_transfer_over_msat as maximum possible, it can
 825                                         // be only reduced later (not increased), so this channel should just be skipped
 826                                         // as not sufficient.
 827                                         if !over_path_minimum_msat && doesnt_exceed_cltv_delta_limit {
 828                                                 hit_minimum_limit = true;
 829                                         } else if contributes_sufficient_value && doesnt_exceed_cltv_delta_limit {
 830                                                 // Note that low contribution here (limited by available_liquidity_msat)
 831                                                 // might violate htlc_minimum_msat on the hops which are next along the
 832                                                 // payment path (upstream to the payee). To avoid that, we recompute
 833                                                 // path fees knowing the final path contribution after constructing it.
 834                                                 let path_htlc_minimum_msat = compute_fees($next_hops_path_htlc_minimum_msat, $directional_info.fees)
 835                                                         .and_then(|fee_msat| fee_msat.checked_add($next_hops_path_htlc_minimum_msat))
 836                                                         .map(|fee_msat| cmp::max(fee_msat, $directional_info.htlc_minimum_msat))
 837                                                         .unwrap_or_else(|| u64::max_value());
 838                                                 let hm_entry = dist.entry($src_node_id);
 839                                                 let old_entry = hm_entry.or_insert_with(|| {
 840                                                         // If there was previously no known way to access
 841                                                         // the source node (recall it goes payee-to-payer) of $chan_id, first add
 842                                                         // a semi-dummy record just to compute the fees to reach the source node.
 843                                                         // This will affect our decision on selecting $chan_id
 844                                                         // as a way to reach the $dest_node_id.
 845                                                         let mut fee_base_msat = u32::max_value();
 846                                                         let mut fee_proportional_millionths = u32::max_value();
 847                                                         if let Some(Some(fees)) = network_nodes.get(&$src_node_id).map(|node| node.lowest_inbound_channel_fees) {
 848                                                                 fee_base_msat = fees.base_msat;
 849                                                                 fee_proportional_millionths = fees.proportional_millionths;
 850                                                         }
 851                                                         PathBuildingHop {
 852                                                                 node_id: $dest_node_id.clone(),
 853                                                                 short_channel_id: 0,
 854                                                                 channel_features: $chan_features,
 855                                                                 fee_msat: 0,
 856                                                                 cltv_expiry_delta: 0,
 857                                                                 src_lowest_inbound_fees: RoutingFees {
 858                                                                         base_msat: fee_base_msat,
 859                                                                         proportional_millionths: fee_proportional_millionths,
 860                                                                 },
 861                                                                 channel_fees: $directional_info.fees,
 862                                                                 next_hops_fee_msat: u64::max_value(),
 863                                                                 hop_use_fee_msat: u64::max_value(),
 864                                                                 total_fee_msat: u64::max_value(),
 865                                                                 htlc_minimum_msat: $directional_info.htlc_minimum_msat,
 866                                                                 path_htlc_minimum_msat,
 867                                                                 path_penalty_msat: u64::max_value(),
 868                                                                 was_processed: false,
 869                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 870                                                                 value_contribution_msat,
 871                                                         }
 872                                                 });
 873
 874                                                 #[allow(unused_mut)] // We only use the mut in cfg(test)
 875                                                 let mut should_process = !old_entry.was_processed;
 876                                                 #[cfg(any(test, feature = "fuzztarget"))]
 877                                                 {
 878                                                         // In test/fuzzing builds, we do extra checks to make sure the skipping
 879                                                         // of already-seen nodes only happens in cases we expect (see below).
 880                                                         if !should_process { should_process = true; }
 881                                                 }
 882
 883                                                 if should_process {
 884                                                         let mut hop_use_fee_msat = 0;
 885                                                         let mut total_fee_msat = $next_hops_fee_msat;
 886
 887                                                         // Ignore hop_use_fee_msat for channel-from-us as we assume all channels-from-us
 888                                                         // will have the same effective-fee
 889                                                         if $src_node_id != our_node_id {
 890                                                                 match compute_fees(amount_to_transfer_over_msat, $directional_info.fees) {
 891                                                                         // max_value means we'll always fail
 892                                                                         // the old_entry.total_fee_msat > total_fee_msat check
 893                                                                         None => total_fee_msat = u64::max_value(),
 894                                                                         Some(fee_msat) => {
 895                                                                                 hop_use_fee_msat = fee_msat;
 896                                                                                 total_fee_msat += hop_use_fee_msat;
 897                                                                                 // When calculating the lowest inbound fees to a node, we
 898                                                                                 // calculate fees here not based on the actual value we think
 899                                                                                 // will flow over this channel, but on the minimum value that
 900                                                                                 // we'll accept flowing over it. The minimum accepted value
 901                                                                                 // is a constant through each path collection run, ensuring
 902                                                                                 // consistent basis. Otherwise we may later find a
 903                                                                                 // different path to the source node that is more expensive,
 904                                                                                 // but which we consider to be cheaper because we are capacity
 905                                                                                 // constrained and the relative fee becomes lower.
 906                                                                                 match compute_fees(minimal_value_contribution_msat, old_entry.src_lowest_inbound_fees)
 907                                                                                                 .map(|a| a.checked_add(total_fee_msat)) {
 908                                                                                         Some(Some(v)) => {
 909                                                                                                 total_fee_msat = v;
 910                                                                                         },
 911                                                                                         _ => {
 912                                                                                                 total_fee_msat = u64::max_value();
 913                                                                                         }
 914                                                                                 };
 915                                                                         }
 916                                                                 }
 917                                                         }
 918
 919                                                         let path_penalty_msat = $next_hops_path_penalty_msat.checked_add(
 920                                                                 scorer.channel_penalty_msat($chan_id.clone(), amount_to_transfer_over_msat, Some(*available_liquidity_msat),
 921                                                                         &$src_node_id, &$dest_node_id)).unwrap_or_else(|| u64::max_value());
 922                                                         let new_graph_node = RouteGraphNode {
 923                                                                 node_id: $src_node_id,
 924                                                                 lowest_fee_to_peer_through_node: total_fee_msat,
 925                                                                 lowest_fee_to_node: $next_hops_fee_msat as u64 + hop_use_fee_msat,
 926                                                                 total_cltv_delta: hop_total_cltv_delta,
 927                                                                 value_contribution_msat: value_contribution_msat,
 928                                                                 path_htlc_minimum_msat,
 929                                                                 path_penalty_msat,
 930                                                         };
 931
 932                                                         // Update the way of reaching $src_node_id with the given $chan_id (from $dest_node_id),
 933                                                         // if this way is cheaper than the already known
 934                                                         // (considering the cost to "reach" this channel from the route destination,
 935                                                         // the cost of using this channel,
 936                                                         // and the cost of routing to the source node of this channel).
 937                                                         // Also, consider that htlc_minimum_msat_difference, because we might end up
 938                                                         // paying it. Consider the following exploit:
 939                                                         // we use 2 paths to transfer 1.5 BTC. One of them is 0-fee normal 1 BTC path,
 940                                                         // and for the other one we picked a 1sat-fee path with htlc_minimum_msat of
 941                                                         // 1 BTC. Now, since the latter is more expensive, we gonna try to cut it
 942                                                         // by 0.5 BTC, but then match htlc_minimum_msat by paying a fee of 0.5 BTC
 943                                                         // to this channel.
 944                                                         // Ideally the scoring could be smarter (e.g. 0.5*htlc_minimum_msat here),
 945                                                         // but it may require additional tracking - we don't want to double-count
 946                                                         // the fees included in $next_hops_path_htlc_minimum_msat, but also
 947                                                         // can't use something that may decrease on future hops.
 948                                                         let old_cost = cmp::max(old_entry.total_fee_msat, old_entry.path_htlc_minimum_msat)
 949                                                                 .checked_add(old_entry.path_penalty_msat)
 950                                                                 .unwrap_or_else(|| u64::max_value());
 951                                                         let new_cost = cmp::max(total_fee_msat, path_htlc_minimum_msat)
 952                                                                 .checked_add(path_penalty_msat)
 953                                                                 .unwrap_or_else(|| u64::max_value());
 954
 955                                                         if !old_entry.was_processed && new_cost < old_cost {
 956                                                                 targets.push(new_graph_node);
 957                                                                 old_entry.next_hops_fee_msat = $next_hops_fee_msat;
 958                                                                 old_entry.hop_use_fee_msat = hop_use_fee_msat;
 959                                                                 old_entry.total_fee_msat = total_fee_msat;
 960                                                                 old_entry.node_id = $dest_node_id.clone();
 961                                                                 old_entry.short_channel_id = $chan_id.clone();
 962                                                                 old_entry.channel_features = $chan_features;
 963                                                                 old_entry.fee_msat = 0; // This value will be later filled with hop_use_fee_msat of the following channel
 964                                                                 old_entry.cltv_expiry_delta = $directional_info.cltv_expiry_delta as u32;
 965                                                                 old_entry.channel_fees = $directional_info.fees;
 966                                                                 old_entry.htlc_minimum_msat = $directional_info.htlc_minimum_msat;
 967                                                                 old_entry.path_htlc_minimum_msat = path_htlc_minimum_msat;
 968                                                                 old_entry.path_penalty_msat = path_penalty_msat;
 969                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 970                                                                 {
 971                                                                         old_entry.value_contribution_msat = value_contribution_msat;
 972                                                                 }
 973                                                                 did_add_update_path_to_src_node = true;
 974                                                         } else if old_entry.was_processed && new_cost < old_cost {
 975                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 976                                                                 {
 977                                                                         // If we're skipping processing a node which was previously
 978                                                                         // processed even though we found another path to it with a
 979                                                                         // cheaper fee, check that it was because the second path we
 980                                                                         // found (which we are processing now) has a lower value
 981                                                                         // contribution due to an HTLC minimum limit.
 982                                                                         //
 983                                                                         // e.g. take a graph with two paths from node 1 to node 2, one
 984                                                                         // through channel A, and one through channel B. Channel A and
 985                                                                         // B are both in the to-process heap, with their scores set by
 986                                                                         // a higher htlc_minimum than fee.
 987                                                                         // Channel A is processed first, and the channels onwards from
 988                                                                         // node 1 are added to the to-process heap. Thereafter, we pop
 989                                                                         // Channel B off of the heap, note that it has a much more
 990                                                                         // restrictive htlc_maximum_msat, and recalculate the fees for
 991                                                                         // all of node 1's channels using the new, reduced, amount.
 992                                                                         //
 993                                                                         // This would be bogus - we'd be selecting a higher-fee path
 994                                                                         // with a lower htlc_maximum_msat instead of the one we'd
 995                                                                         // already decided to use.
 996                                                                         debug_assert!(path_htlc_minimum_msat < old_entry.path_htlc_minimum_msat);
 997                                                                         debug_assert!(
 998                                                                                 value_contribution_msat + path_penalty_msat <
 999                                                                                 old_entry.value_contribution_msat + old_entry.path_penalty_msat
1000                                                                         );
1001                                                                 }
1002                                                         }
1003                                                 }
1004                                         }
1005                                 }
1006                         }
1007                         did_add_update_path_to_src_node
1008                 } }
1009         }
1010
1011         let empty_node_features = NodeFeatures::empty();
1012         // Find ways (channels with destination) to reach a given node and store them
1013         // in the corresponding data structures (routing graph etc).
1014         // $fee_to_target_msat represents how much it costs to reach to this node from the payee,
1015         // meaning how much will be paid in fees after this node (to the best of our knowledge).
1016         // This data can later be helpful to optimize routing (pay lower fees).
1017         macro_rules! add_entries_to_cheapest_to_target_node {
1018                 ( $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, $next_hops_cltv_delta: expr ) => {
1019                         let skip_node = if let Some(elem) = dist.get_mut(&$node_id) {
1020                                 let was_processed = elem.was_processed;
1021                                 elem.was_processed = true;
1022                                 was_processed
1023                         } else {
1024                                 // Entries are added to dist in add_entry!() when there is a channel from a node.
1025                                 // Because there are no channels from payee, it will not have a dist entry at this point.
1026                                 // If we're processing any other node, it is always be the result of a channel from it.
1027                                 assert_eq!($node_id, payee_node_id);
1028                                 false
1029                         };
1030
1031                         if !skip_node {
1032                                 if let Some(first_channels) = first_hop_targets.get(&$node_id) {
1033                                         for (ref first_hop, ref features, ref outbound_capacity_msat, _) in first_channels {
1034                                                 add_entry!(first_hop, our_node_id, $node_id, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, $fee_to_target_msat, $next_hops_value_contribution, $next_hops_path_htlc_minimum_msat, $next_hops_path_penalty_msat, $next_hops_cltv_delta);
1035                                         }
1036                                 }
1037
1038                                 let features = if let Some(node_info) = $node.announcement_info.as_ref() {
1039                                         &node_info.features
1040                                 } else {
1041                                         &empty_node_features
1042                                 };
1043
1044                                 if !features.requires_unknown_bits() {
1045                                         for chan_id in $node.channels.iter() {
1046                                                 let chan = network_channels.get(chan_id).unwrap();
1047                                                 if !chan.features.requires_unknown_bits() {
1048                                                         if chan.node_one == $node_id {
1049                                                                 // ie $node is one, ie next hop in A* is two, via the two_to_one channel
1050                                                                 if first_hops.is_none() || chan.node_two != our_node_id {
1051                                                                         if let Some(two_to_one) = chan.two_to_one.as_ref() {
1052                                                                                 if two_to_one.enabled {
1053                                                                                         add_entry!(chan_id, chan.node_two, chan.node_one, two_to_one, chan.capacity_sats, &chan.features, $fee_to_target_msat, $next_hops_value_contribution, $next_hops_path_htlc_minimum_msat, $next_hops_path_penalty_msat, $next_hops_cltv_delta);
1054                                                                                 }
1055                                                                         }
1056                                                                 }
1057                                                         } else {
1058                                                                 if first_hops.is_none() || chan.node_one != our_node_id{
1059                                                                         if let Some(one_to_two) = chan.one_to_two.as_ref() {
1060                                                                                 if one_to_two.enabled {
1061                                                                                         add_entry!(chan_id, chan.node_one, chan.node_two, one_to_two, chan.capacity_sats, &chan.features, $fee_to_target_msat, $next_hops_value_contribution, $next_hops_path_htlc_minimum_msat, $next_hops_path_penalty_msat, $next_hops_cltv_delta);
1062                                                                                 }
1063                                                                         }
1064                                                                 }
1065                                                         }
1066                                                 }
1067                                         }
1068                                 }
1069                         }
1070                 };
1071         }
1072
1073         let mut payment_paths = Vec::<PaymentPath>::new();
1074
1075         // TODO: diversify by nodes (so that all paths aren't doomed if one node is offline).
1076         'paths_collection: loop {
1077                 // For every new path, start from scratch, except
1078                 // bookkept_channels_liquidity_available_msat, which will improve
1079                 // the further iterations of path finding. Also don't erase first_hop_targets.
1080                 targets.clear();
1081                 dist.clear();
1082                 hit_minimum_limit = false;
1083
1084                 // If first hop is a private channel and the only way to reach the payee, this is the only
1085                 // place where it could be added.
1086                 if let Some(first_channels) = first_hop_targets.get(&payee_node_id) {
1087                         for (ref first_hop, ref features, ref outbound_capacity_msat, _) in first_channels {
1088                                 let added = add_entry!(first_hop, our_node_id, payee_node_id, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, 0, path_value_msat, 0, 0u64, 0);
1089                                 log_trace!(logger, "{} direct route to payee via SCID {}", if added { "Added" } else { "Skipped" }, first_hop);
1090                         }
1091                 }
1092
1093                 // Add the payee as a target, so that the payee-to-payer
1094                 // search algorithm knows what to start with.
1095                 match network_nodes.get(&payee_node_id) {
1096                         // The payee is not in our network graph, so nothing to add here.
1097                         // There is still a chance of reaching them via last_hops though,
1098                         // so don't yet fail the payment here.
1099                         // If not, targets.pop() will not even let us enter the loop in step 2.
1100                         None => {},
1101                         Some(node) => {
1102                                 add_entries_to_cheapest_to_target_node!(node, payee_node_id, 0, path_value_msat, 0, 0u64, 0);
1103                         },
1104                 }
1105
1106                 // Step (2).
1107                 // If a caller provided us with last hops, add them to routing targets. Since this happens
1108                 // earlier than general path finding, they will be somewhat prioritized, although currently
1109                 // it matters only if the fees are exactly the same.
1110                 for route in payment_params.route_hints.iter().filter(|route| !route.0.is_empty()) {
1111                         let first_hop_in_route = &(route.0)[0];
1112                         let have_hop_src_in_graph =
1113                                 // Only add the hops in this route to our candidate set if either
1114                                 // we have a direct channel to the first hop or the first hop is
1115                                 // in the regular network graph.
1116                                 first_hop_targets.get(&NodeId::from_pubkey(&first_hop_in_route.src_node_id)).is_some() ||
1117                                 network_nodes.get(&NodeId::from_pubkey(&first_hop_in_route.src_node_id)).is_some();
1118                         if have_hop_src_in_graph {
1119                                 // We start building the path from reverse, i.e., from payee
1120                                 // to the first RouteHintHop in the path.
1121                                 let hop_iter = route.0.iter().rev();
1122                                 let prev_hop_iter = core::iter::once(&payment_params.payee_pubkey).chain(
1123                                         route.0.iter().skip(1).rev().map(|hop| &hop.src_node_id));
1124                                 let mut hop_used = true;
1125                                 let mut aggregate_next_hops_fee_msat: u64 = 0;
1126                                 let mut aggregate_next_hops_path_htlc_minimum_msat: u64 = 0;
1127                                 let mut aggregate_next_hops_path_penalty_msat: u64 = 0;
1128                                 let mut aggregate_next_hops_cltv_delta: u32 = 0;
1129
1130                                 for (idx, (hop, prev_hop_id)) in hop_iter.zip(prev_hop_iter).enumerate() {
1131                                         // BOLT 11 doesn't allow inclusion of features for the last hop hints, which
1132                                         // really sucks, cause we're gonna need that eventually.
1133                                         let hop_htlc_minimum_msat: u64 = hop.htlc_minimum_msat.unwrap_or(0);
1134
1135                                         let directional_info = DummyDirectionalChannelInfo {
1136                                                 cltv_expiry_delta: hop.cltv_expiry_delta as u32,
1137                                                 htlc_minimum_msat: hop_htlc_minimum_msat,
1138                                                 htlc_maximum_msat: hop.htlc_maximum_msat,
1139                                                 fees: hop.fees,
1140                                         };
1141
1142                                         // We want a value of final_value_msat * ROUTE_CAPACITY_PROVISION_FACTOR but we
1143                                         // need it to increment at each hop by the fee charged at later hops. Further,
1144                                         // we need to ensure we round up when we divide to get satoshis.
1145                                         let channel_cap_msat = final_value_msat
1146                                                 .checked_mul(ROUTE_CAPACITY_PROVISION_FACTOR).and_then(|v| v.checked_add(aggregate_next_hops_fee_msat))
1147                                                 .unwrap_or(u64::max_value());
1148                                         let channel_cap_sat = match channel_cap_msat.checked_add(999) {
1149                                                 None => break, // We overflowed above, just ignore this route hint
1150                                                 Some(val) => Some(val / 1000),
1151                                         };
1152
1153                                         let src_node_id = NodeId::from_pubkey(&hop.src_node_id);
1154                                         let dest_node_id = NodeId::from_pubkey(&prev_hop_id);
1155                                         aggregate_next_hops_path_penalty_msat = aggregate_next_hops_path_penalty_msat
1156                                                 .checked_add(scorer.channel_penalty_msat(hop.short_channel_id, final_value_msat, None, &src_node_id, &dest_node_id))
1157                                                 .unwrap_or_else(|| u64::max_value());
1158
1159                                         aggregate_next_hops_cltv_delta = aggregate_next_hops_cltv_delta
1160                                                 .checked_add(hop.cltv_expiry_delta as u32)
1161                                                 .unwrap_or_else(|| u32::max_value());
1162
1163                                         // We assume that the recipient only included route hints for routes which had
1164                                         // sufficient value to route `final_value_msat`. Note that in the case of "0-value"
1165                                         // invoices where the invoice does not specify value this may not be the case, but
1166                                         // better to include the hints than not.
1167                                         if !add_entry!(hop.short_channel_id, src_node_id, dest_node_id, directional_info, channel_cap_sat, &empty_channel_features, aggregate_next_hops_fee_msat, path_value_msat, aggregate_next_hops_path_htlc_minimum_msat, aggregate_next_hops_path_penalty_msat, aggregate_next_hops_cltv_delta) {
1168                                                 // If this hop was not used then there is no use checking the preceding hops
1169                                                 // in the RouteHint. We can break by just searching for a direct channel between
1170                                                 // last checked hop and first_hop_targets
1171                                                 hop_used = false;
1172                                         }
1173
1174                                         // Searching for a direct channel between last checked hop and first_hop_targets
1175                                         if let Some(first_channels) = first_hop_targets.get(&NodeId::from_pubkey(&prev_hop_id)) {
1176                                                 for (ref first_hop, ref features, ref outbound_capacity_msat, _) in first_channels {
1177                                                         add_entry!(first_hop, our_node_id , NodeId::from_pubkey(&prev_hop_id), dummy_directional_info, Some(outbound_capacity_msat / 1000), features, aggregate_next_hops_fee_msat, path_value_msat, aggregate_next_hops_path_htlc_minimum_msat, aggregate_next_hops_path_penalty_msat, aggregate_next_hops_cltv_delta);
1178                                                 }
1179                                         }
1180
1181                                         if !hop_used {
1182                                                 break;
1183                                         }
1184
1185                                         // In the next values of the iterator, the aggregate fees already reflects
1186                                         // the sum of value sent from payer (final_value_msat) and routing fees
1187                                         // for the last node in the RouteHint. We need to just add the fees to
1188                                         // route through the current node so that the preceeding node (next iteration)
1189                                         // can use it.
1190                                         let hops_fee = compute_fees(aggregate_next_hops_fee_msat + final_value_msat, hop.fees)
1191                                                 .map_or(None, |inc| inc.checked_add(aggregate_next_hops_fee_msat));
1192                                         aggregate_next_hops_fee_msat = if let Some(val) = hops_fee { val } else { break; };
1193
1194                                         let hop_htlc_minimum_msat_inc = if let Some(val) = compute_fees(aggregate_next_hops_path_htlc_minimum_msat, hop.fees) { val } else { break; };
1195                                         let hops_path_htlc_minimum = aggregate_next_hops_path_htlc_minimum_msat
1196                                                 .checked_add(hop_htlc_minimum_msat_inc);
1197                                         aggregate_next_hops_path_htlc_minimum_msat = if let Some(val) = hops_path_htlc_minimum { cmp::max(hop_htlc_minimum_msat, val) } else { break; };
1198
1199                                         if idx == route.0.len() - 1 {
1200                                                 // The last hop in this iterator is the first hop in
1201                                                 // overall RouteHint.
1202                                                 // If this hop connects to a node with which we have a direct channel,
1203                                                 // ignore the network graph and, if the last hop was added, add our
1204                                                 // direct channel to the candidate set.
1205                                                 //
1206                                                 // Note that we *must* check if the last hop was added as `add_entry`
1207                                                 // always assumes that the third argument is a node to which we have a
1208                                                 // path.
1209                                                 if let Some(first_channels) = first_hop_targets.get(&NodeId::from_pubkey(&hop.src_node_id)) {
1210                                                         for (ref first_hop, ref features, ref outbound_capacity_msat, _) in first_channels {
1211                                                                 add_entry!(first_hop, our_node_id , NodeId::from_pubkey(&hop.src_node_id), dummy_directional_info, Some(outbound_capacity_msat / 1000), features, aggregate_next_hops_fee_msat, path_value_msat, aggregate_next_hops_path_htlc_minimum_msat, aggregate_next_hops_path_penalty_msat, aggregate_next_hops_cltv_delta);
1212                                                         }
1213                                                 }
1214                                         }
1215                                 }
1216                         }
1217                 }
1218
1219                 log_trace!(logger, "Starting main path collection loop with {} nodes pre-filled from first/last hops.", targets.len());
1220
1221                 // At this point, targets are filled with the data from first and
1222                 // last hops communicated by the caller, and the payment receiver.
1223                 let mut found_new_path = false;
1224
1225                 // Step (3).
1226                 // If this loop terminates due the exhaustion of targets, two situations are possible:
1227                 // - not enough outgoing liquidity:
1228                 //   0 < already_collected_value_msat < final_value_msat
1229                 // - enough outgoing liquidity:
1230                 //   final_value_msat <= already_collected_value_msat < recommended_value_msat
1231                 // Both these cases (and other cases except reaching recommended_value_msat) mean that
1232                 // paths_collection will be stopped because found_new_path==false.
1233                 // This is not necessarily a routing failure.
1234                 '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() {
1235
1236                         // Since we're going payee-to-payer, hitting our node as a target means we should stop
1237                         // traversing the graph and arrange the path out of what we found.
1238                         if node_id == our_node_id {
1239                                 let mut new_entry = dist.remove(&our_node_id).unwrap();
1240                                 let mut ordered_hops = vec!((new_entry.clone(), NodeFeatures::empty()));
1241
1242                                 'path_walk: loop {
1243                                         let mut features_set = false;
1244                                         if let Some(first_channels) = first_hop_targets.get(&ordered_hops.last().unwrap().0.node_id) {
1245                                                 for (scid, _, _, ref features) in first_channels {
1246                                                         if *scid == ordered_hops.last().unwrap().0.short_channel_id {
1247                                                                 ordered_hops.last_mut().unwrap().1 = features.clone();
1248                                                                 features_set = true;
1249                                                                 break;
1250                                                         }
1251                                                 }
1252                                         }
1253                                         if !features_set {
1254                                                 if let Some(node) = network_nodes.get(&ordered_hops.last().unwrap().0.node_id) {
1255                                                         if let Some(node_info) = node.announcement_info.as_ref() {
1256                                                                 ordered_hops.last_mut().unwrap().1 = node_info.features.clone();
1257                                                         } else {
1258                                                                 ordered_hops.last_mut().unwrap().1 = NodeFeatures::empty();
1259                                                         }
1260                                                 } else {
1261                                                         // We should be able to fill in features for everything except the last
1262                                                         // hop, if the last hop was provided via a BOLT 11 invoice (though we
1263                                                         // should be able to extend it further as BOLT 11 does have feature
1264                                                         // flags for the last hop node itself).
1265                                                         assert!(ordered_hops.last().unwrap().0.node_id == payee_node_id);
1266                                                 }
1267                                         }
1268
1269                                         // Means we succesfully traversed from the payer to the payee, now
1270                                         // save this path for the payment route. Also, update the liquidity
1271                                         // remaining on the used hops, so that we take them into account
1272                                         // while looking for more paths.
1273                                         if ordered_hops.last().unwrap().0.node_id == payee_node_id {
1274                                                 break 'path_walk;
1275                                         }
1276
1277                                         new_entry = match dist.remove(&ordered_hops.last().unwrap().0.node_id) {
1278                                                 Some(payment_hop) => payment_hop,
1279                                                 // We can't arrive at None because, if we ever add an entry to targets,
1280                                                 // we also fill in the entry in dist (see add_entry!).
1281                                                 None => unreachable!(),
1282                                         };
1283                                         // We "propagate" the fees one hop backward (topologically) here,
1284                                         // so that fees paid for a HTLC forwarding on the current channel are
1285                                         // associated with the previous channel (where they will be subtracted).
1286                                         ordered_hops.last_mut().unwrap().0.fee_msat = new_entry.hop_use_fee_msat;
1287                                         ordered_hops.last_mut().unwrap().0.cltv_expiry_delta = new_entry.cltv_expiry_delta;
1288                                         ordered_hops.push((new_entry.clone(), NodeFeatures::empty()));
1289                                 }
1290                                 ordered_hops.last_mut().unwrap().0.fee_msat = value_contribution_msat;
1291                                 ordered_hops.last_mut().unwrap().0.hop_use_fee_msat = 0;
1292                                 ordered_hops.last_mut().unwrap().0.cltv_expiry_delta = final_cltv_expiry_delta;
1293
1294                                 log_trace!(logger, "Found a path back to us from the target with {} hops contributing up to {} msat: {:?}",
1295                                         ordered_hops.len(), value_contribution_msat, ordered_hops);
1296
1297                                 let mut payment_path = PaymentPath {hops: ordered_hops};
1298
1299                                 // We could have possibly constructed a slightly inconsistent path: since we reduce
1300                                 // value being transferred along the way, we could have violated htlc_minimum_msat
1301                                 // on some channels we already passed (assuming dest->source direction). Here, we
1302                                 // recompute the fees again, so that if that's the case, we match the currently
1303                                 // underpaid htlc_minimum_msat with fees.
1304                                 payment_path.update_value_and_recompute_fees(cmp::min(value_contribution_msat, final_value_msat));
1305
1306                                 // Since a path allows to transfer as much value as
1307                                 // the smallest channel it has ("bottleneck"), we should recompute
1308                                 // the fees so sender HTLC don't overpay fees when traversing
1309                                 // larger channels than the bottleneck. This may happen because
1310                                 // when we were selecting those channels we were not aware how much value
1311                                 // this path will transfer, and the relative fee for them
1312                                 // might have been computed considering a larger value.
1313                                 // Remember that we used these channels so that we don't rely
1314                                 // on the same liquidity in future paths.
1315                                 let mut prevented_redundant_path_selection = false;
1316                                 for (payment_hop, _) in payment_path.hops.iter() {
1317                                         let channel_liquidity_available_msat = bookkept_channels_liquidity_available_msat.get_mut(&payment_hop.short_channel_id).unwrap();
1318                                         let mut spent_on_hop_msat = value_contribution_msat;
1319                                         let next_hops_fee_msat = payment_hop.next_hops_fee_msat;
1320                                         spent_on_hop_msat += next_hops_fee_msat;
1321                                         if spent_on_hop_msat == *channel_liquidity_available_msat {
1322                                                 // If this path used all of this channel's available liquidity, we know
1323                                                 // this path will not be selected again in the next loop iteration.
1324                                                 prevented_redundant_path_selection = true;
1325                                         }
1326                                         *channel_liquidity_available_msat -= spent_on_hop_msat;
1327                                 }
1328                                 if !prevented_redundant_path_selection {
1329                                         // If we weren't capped by hitting a liquidity limit on a channel in the path,
1330                                         // we'll probably end up picking the same path again on the next iteration.
1331                                         // Decrease the available liquidity of a hop in the middle of the path.
1332                                         let victim_scid = payment_path.hops[(payment_path.hops.len() - 1) / 2].0.short_channel_id;
1333                                         log_trace!(logger, "Disabling channel {} for future path building iterations to avoid duplicates.", victim_scid);
1334                                         let victim_liquidity = bookkept_channels_liquidity_available_msat.get_mut(&victim_scid).unwrap();
1335                                         *victim_liquidity = 0;
1336                                 }
1337
1338                                 // Track the total amount all our collected paths allow to send so that we:
1339                                 // - know when to stop looking for more paths
1340                                 // - know which of the hops are useless considering how much more sats we need
1341                                 //   (contributes_sufficient_value)
1342                                 already_collected_value_msat += value_contribution_msat;
1343
1344                                 payment_paths.push(payment_path);
1345                                 found_new_path = true;
1346                                 break 'path_construction;
1347                         }
1348
1349                         // If we found a path back to the payee, we shouldn't try to process it again. This is
1350                         // the equivalent of the `elem.was_processed` check in
1351                         // add_entries_to_cheapest_to_target_node!() (see comment there for more info).
1352                         if node_id == payee_node_id { continue 'path_construction; }
1353
1354                         // Otherwise, since the current target node is not us,
1355                         // keep "unrolling" the payment graph from payee to payer by
1356                         // finding a way to reach the current target from the payer side.
1357                         match network_nodes.get(&node_id) {
1358                                 None => {},
1359                                 Some(node) => {
1360                                         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);
1361                                 },
1362                         }
1363                 }
1364
1365                 if !allow_mpp {
1366                         // If we don't support MPP, no use trying to gather more value ever.
1367                         break 'paths_collection;
1368                 }
1369
1370                 // Step (4).
1371                 // Stop either when the recommended value is reached or if no new path was found in this
1372                 // iteration.
1373                 // In the latter case, making another path finding attempt won't help,
1374                 // because we deterministically terminated the search due to low liquidity.
1375                 if already_collected_value_msat >= recommended_value_msat || !found_new_path {
1376                         log_trace!(logger, "Have now collected {} msat (seeking {} msat) in paths. Last path loop {} a new path.",
1377                                 already_collected_value_msat, recommended_value_msat, if found_new_path { "found" } else { "did not find" });
1378                         break 'paths_collection;
1379                 } else if found_new_path && already_collected_value_msat == final_value_msat && payment_paths.len() == 1 {
1380                         // Further, if this was our first walk of the graph, and we weren't limited by an
1381                         // htlc_minimum_msat, return immediately because this path should suffice. If we were
1382                         // limited by an htlc_minimum_msat value, find another path with a higher value,
1383                         // potentially allowing us to pay fees to meet the htlc_minimum on the new path while
1384                         // still keeping a lower total fee than this path.
1385                         if !hit_minimum_limit {
1386                                 log_trace!(logger, "Collected exactly our payment amount on the first pass, without hitting an htlc_minimum_msat limit, exiting.");
1387                                 break 'paths_collection;
1388                         }
1389                         log_trace!(logger, "Collected our payment amount on the first pass, but running again to collect extra paths with a potentially higher limit.");
1390                         path_value_msat = recommended_value_msat;
1391                 }
1392         }
1393
1394         // Step (5).
1395         if payment_paths.len() == 0 {
1396                 return Err(LightningError{err: "Failed to find a path to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1397         }
1398
1399         if already_collected_value_msat < final_value_msat {
1400                 return Err(LightningError{err: "Failed to find a sufficient route to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1401         }
1402
1403         // Sort by total fees and take the best paths.
1404         payment_paths.sort_by_key(|path| path.get_total_fee_paid_msat());
1405         if payment_paths.len() > 50 {
1406                 payment_paths.truncate(50);
1407         }
1408
1409         // Draw multiple sufficient routes by randomly combining the selected paths.
1410         let mut drawn_routes = Vec::new();
1411         for i in 0..payment_paths.len() {
1412                 let mut cur_route = Vec::<PaymentPath>::new();
1413                 let mut aggregate_route_value_msat = 0;
1414
1415                 // Step (6).
1416                 // TODO: real random shuffle
1417                 // Currently just starts with i_th and goes up to i-1_th in a looped way.
1418                 let cur_payment_paths = [&payment_paths[i..], &payment_paths[..i]].concat();
1419
1420                 // Step (7).
1421                 for payment_path in cur_payment_paths {
1422                         cur_route.push(payment_path.clone());
1423                         aggregate_route_value_msat += payment_path.get_value_msat();
1424                         if aggregate_route_value_msat > final_value_msat {
1425                                 // Last path likely overpaid. Substract it from the most expensive
1426                                 // (in terms of proportional fee) path in this route and recompute fees.
1427                                 // This might be not the most economically efficient way, but fewer paths
1428                                 // also makes routing more reliable.
1429                                 let mut overpaid_value_msat = aggregate_route_value_msat - final_value_msat;
1430
1431                                 // First, drop some expensive low-value paths entirely if possible.
1432                                 // Sort by value so that we drop many really-low values first, since
1433                                 // fewer paths is better: the payment is less likely to fail.
1434                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1435                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1436                                 cur_route.sort_by_key(|path| path.get_value_msat());
1437                                 // We should make sure that at least 1 path left.
1438                                 let mut paths_left = cur_route.len();
1439                                 cur_route.retain(|path| {
1440                                         if paths_left == 1 {
1441                                                 return true
1442                                         }
1443                                         let mut keep = true;
1444                                         let path_value_msat = path.get_value_msat();
1445                                         if path_value_msat <= overpaid_value_msat {
1446                                                 keep = false;
1447                                                 overpaid_value_msat -= path_value_msat;
1448                                                 paths_left -= 1;
1449                                         }
1450                                         keep
1451                                 });
1452
1453                                 if overpaid_value_msat == 0 {
1454                                         break;
1455                                 }
1456
1457                                 assert!(cur_route.len() > 0);
1458
1459                                 // Step (8).
1460                                 // Now, substract the overpaid value from the most-expensive path.
1461                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1462                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1463                                 cur_route.sort_by_key(|path| { path.hops.iter().map(|hop| hop.0.channel_fees.proportional_millionths as u64).sum::<u64>() });
1464                                 let expensive_payment_path = cur_route.first_mut().unwrap();
1465                                 // We already dropped all the small channels above, meaning all the
1466                                 // remaining channels are larger than remaining overpaid_value_msat.
1467                                 // Thus, this can't be negative.
1468                                 let expensive_path_new_value_msat = expensive_payment_path.get_value_msat() - overpaid_value_msat;
1469                                 expensive_payment_path.update_value_and_recompute_fees(expensive_path_new_value_msat);
1470                                 break;
1471                         }
1472                 }
1473                 drawn_routes.push(cur_route);
1474         }
1475
1476         // Step (9).
1477         // Select the best route by lowest total fee.
1478         drawn_routes.sort_by_key(|paths| paths.iter().map(|path| path.get_total_fee_paid_msat()).sum::<u64>());
1479         let mut selected_paths = Vec::<Vec<Result<RouteHop, LightningError>>>::new();
1480         for payment_path in drawn_routes.first().unwrap() {
1481                 selected_paths.push(payment_path.hops.iter().map(|(payment_hop, node_features)| {
1482                         Ok(RouteHop {
1483                                 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)})?,
1484                                 node_features: node_features.clone(),
1485                                 short_channel_id: payment_hop.short_channel_id,
1486                                 channel_features: payment_hop.channel_features.clone(),
1487                                 fee_msat: payment_hop.fee_msat,
1488                                 cltv_expiry_delta: payment_hop.cltv_expiry_delta,
1489                         })
1490                 }).collect());
1491         }
1492
1493         if let Some(features) = &payment_params.features {
1494                 for path in selected_paths.iter_mut() {
1495                         if let Ok(route_hop) = path.last_mut().unwrap() {
1496                                 route_hop.node_features = features.to_context();
1497                         }
1498                 }
1499         }
1500
1501         let route = Route {
1502                 paths: selected_paths.into_iter().map(|path| path.into_iter().collect()).collect::<Result<Vec<_>, _>>()?,
1503                 payment_params: Some(payment_params.clone()),
1504         };
1505         log_info!(logger, "Got route to {}: {}", payment_params.payee_pubkey, log_route!(route));
1506         Ok(route)
1507 }
1508
1509 #[cfg(test)]
1510 mod tests {
1511         use routing::scoring::Score;
1512         use routing::network_graph::{NetworkGraph, NetGraphMsgHandler, NodeId};
1513         use routing::router::{get_route, PaymentParameters, Route, RouteHint, RouteHintHop, RouteHop, RoutingFees};
1514         use chain::transaction::OutPoint;
1515         use ln::features::{ChannelFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
1516         use ln::msgs::{ErrorAction, LightningError, OptionalField, UnsignedChannelAnnouncement, ChannelAnnouncement, RoutingMessageHandler,
1517            NodeAnnouncement, UnsignedNodeAnnouncement, ChannelUpdate, UnsignedChannelUpdate};
1518         use ln::channelmanager;
1519         use util::test_utils;
1520         use util::ser::Writeable;
1521         #[cfg(c_bindings)]
1522         use util::ser::Writer;
1523
1524         use bitcoin::hashes::sha256d::Hash as Sha256dHash;
1525         use bitcoin::hashes::Hash;
1526         use bitcoin::network::constants::Network;
1527         use bitcoin::blockdata::constants::genesis_block;
1528         use bitcoin::blockdata::script::Builder;
1529         use bitcoin::blockdata::opcodes;
1530         use bitcoin::blockdata::transaction::TxOut;
1531
1532         use hex;
1533
1534         use bitcoin::secp256k1::key::{PublicKey,SecretKey};
1535         use bitcoin::secp256k1::{Secp256k1, All};
1536
1537         use prelude::*;
1538         use sync::{self, Arc};
1539
1540         fn get_channel_details(short_channel_id: Option<u64>, node_id: PublicKey,
1541                         features: InitFeatures, outbound_capacity_msat: u64) -> channelmanager::ChannelDetails {
1542                 channelmanager::ChannelDetails {
1543                         channel_id: [0; 32],
1544                         counterparty: channelmanager::ChannelCounterparty {
1545                                 features,
1546                                 node_id,
1547                                 unspendable_punishment_reserve: 0,
1548                                 forwarding_info: None,
1549                         },
1550                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
1551                         short_channel_id,
1552                         channel_value_satoshis: 0,
1553                         user_channel_id: 0,
1554                         balance_msat: 0,
1555                         outbound_capacity_msat,
1556                         inbound_capacity_msat: 42,
1557                         unspendable_punishment_reserve: None,
1558                         confirmations_required: None,
1559                         force_close_spend_delay: None,
1560                         is_outbound: true, is_funding_locked: true,
1561                         is_usable: true, is_public: true,
1562                 }
1563         }
1564
1565         // Using the same keys for LN and BTC ids
1566         fn add_channel(
1567                 net_graph_msg_handler: &NetGraphMsgHandler<Arc<NetworkGraph>, Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>,
1568                 secp_ctx: &Secp256k1<All>, node_1_privkey: &SecretKey, node_2_privkey: &SecretKey, features: ChannelFeatures, short_channel_id: u64
1569         ) {
1570                 let node_id_1 = PublicKey::from_secret_key(&secp_ctx, node_1_privkey);
1571                 let node_id_2 = PublicKey::from_secret_key(&secp_ctx, node_2_privkey);
1572
1573                 let unsigned_announcement = UnsignedChannelAnnouncement {
1574                         features,
1575                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1576                         short_channel_id,
1577                         node_id_1,
1578                         node_id_2,
1579                         bitcoin_key_1: node_id_1,
1580                         bitcoin_key_2: node_id_2,
1581                         excess_data: Vec::new(),
1582                 };
1583
1584                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1585                 let valid_announcement = ChannelAnnouncement {
1586                         node_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1587                         node_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1588                         bitcoin_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1589                         bitcoin_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1590                         contents: unsigned_announcement.clone(),
1591                 };
1592                 match net_graph_msg_handler.handle_channel_announcement(&valid_announcement) {
1593                         Ok(res) => assert!(res),
1594                         _ => panic!()
1595                 };
1596         }
1597
1598         fn update_channel(
1599                 net_graph_msg_handler: &NetGraphMsgHandler<Arc<NetworkGraph>, Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>,
1600                 secp_ctx: &Secp256k1<All>, node_privkey: &SecretKey, update: UnsignedChannelUpdate
1601         ) {
1602                 let msghash = hash_to_message!(&Sha256dHash::hash(&update.encode()[..])[..]);
1603                 let valid_channel_update = ChannelUpdate {
1604                         signature: secp_ctx.sign(&msghash, node_privkey),
1605                         contents: update.clone()
1606                 };
1607
1608                 match net_graph_msg_handler.handle_channel_update(&valid_channel_update) {
1609                         Ok(res) => assert!(res),
1610                         Err(_) => panic!()
1611                 };
1612         }
1613
1614         fn add_or_update_node(
1615                 net_graph_msg_handler: &NetGraphMsgHandler<Arc<NetworkGraph>, Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>,
1616                 secp_ctx: &Secp256k1<All>, node_privkey: &SecretKey, features: NodeFeatures, timestamp: u32
1617         ) {
1618                 let node_id = PublicKey::from_secret_key(&secp_ctx, node_privkey);
1619                 let unsigned_announcement = UnsignedNodeAnnouncement {
1620                         features,
1621                         timestamp,
1622                         node_id,
1623                         rgb: [0; 3],
1624                         alias: [0; 32],
1625                         addresses: Vec::new(),
1626                         excess_address_data: Vec::new(),
1627                         excess_data: Vec::new(),
1628                 };
1629                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1630                 let valid_announcement = NodeAnnouncement {
1631                         signature: secp_ctx.sign(&msghash, node_privkey),
1632                         contents: unsigned_announcement.clone()
1633                 };
1634
1635                 match net_graph_msg_handler.handle_node_announcement(&valid_announcement) {
1636                         Ok(_) => (),
1637                         Err(_) => panic!()
1638                 };
1639         }
1640
1641         fn get_nodes(secp_ctx: &Secp256k1<All>) -> (SecretKey, PublicKey, Vec<SecretKey>, Vec<PublicKey>) {
1642                 let privkeys: Vec<SecretKey> = (2..10).map(|i| {
1643                         SecretKey::from_slice(&hex::decode(format!("{:02}", i).repeat(32)).unwrap()[..]).unwrap()
1644                 }).collect();
1645
1646                 let pubkeys = privkeys.iter().map(|secret| PublicKey::from_secret_key(&secp_ctx, secret)).collect();
1647
1648                 let our_privkey = SecretKey::from_slice(&hex::decode("01".repeat(32)).unwrap()[..]).unwrap();
1649                 let our_id = PublicKey::from_secret_key(&secp_ctx, &our_privkey);
1650
1651                 (our_privkey, our_id, privkeys, pubkeys)
1652         }
1653
1654         fn id_to_feature_flags(id: u8) -> Vec<u8> {
1655                 // Set the feature flags to the id'th odd (ie non-required) feature bit so that we can
1656                 // test for it later.
1657                 let idx = (id - 1) * 2 + 1;
1658                 if idx > 8*3 {
1659                         vec![1 << (idx - 8*3), 0, 0, 0]
1660                 } else if idx > 8*2 {
1661                         vec![1 << (idx - 8*2), 0, 0]
1662                 } else if idx > 8*1 {
1663                         vec![1 << (idx - 8*1), 0]
1664                 } else {
1665                         vec![1 << idx]
1666                 }
1667         }
1668
1669         fn build_graph() -> (
1670                 Secp256k1<All>,
1671                 sync::Arc<NetworkGraph>,
1672                 NetGraphMsgHandler<sync::Arc<NetworkGraph>, sync::Arc<test_utils::TestChainSource>, sync::Arc<crate::util::test_utils::TestLogger>>,
1673                 sync::Arc<test_utils::TestChainSource>,
1674                 sync::Arc<test_utils::TestLogger>,
1675         ) {
1676                 let secp_ctx = Secp256k1::new();
1677                 let logger = Arc::new(test_utils::TestLogger::new());
1678                 let chain_monitor = Arc::new(test_utils::TestChainSource::new(Network::Testnet));
1679                 let network_graph = Arc::new(NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash()));
1680                 let net_graph_msg_handler = NetGraphMsgHandler::new(Arc::clone(&network_graph), None, Arc::clone(&logger));
1681                 // Build network from our_id to node6:
1682                 //
1683                 //        -1(1)2-  node0  -1(3)2-
1684                 //       /                       \
1685                 // our_id -1(12)2- node7 -1(13)2--- node2
1686                 //       \                       /
1687                 //        -1(2)2-  node1  -1(4)2-
1688                 //
1689                 //
1690                 // chan1  1-to-2: disabled
1691                 // chan1  2-to-1: enabled, 0 fee
1692                 //
1693                 // chan2  1-to-2: enabled, ignored fee
1694                 // chan2  2-to-1: enabled, 0 fee
1695                 //
1696                 // chan3  1-to-2: enabled, 0 fee
1697                 // chan3  2-to-1: enabled, 100 msat fee
1698                 //
1699                 // chan4  1-to-2: enabled, 100% fee
1700                 // chan4  2-to-1: enabled, 0 fee
1701                 //
1702                 // chan12 1-to-2: enabled, ignored fee
1703                 // chan12 2-to-1: enabled, 0 fee
1704                 //
1705                 // chan13 1-to-2: enabled, 200% fee
1706                 // chan13 2-to-1: enabled, 0 fee
1707                 //
1708                 //
1709                 //       -1(5)2- node3 -1(8)2--
1710                 //       |         2          |
1711                 //       |       (11)         |
1712                 //      /          1           \
1713                 // node2--1(6)2- node4 -1(9)2--- node6 (not in global route map)
1714                 //      \                      /
1715                 //       -1(7)2- node5 -1(10)2-
1716                 //
1717                 // Channels 5, 8, 9 and 10 are private channels.
1718                 //
1719                 // chan5  1-to-2: enabled, 100 msat fee
1720                 // chan5  2-to-1: enabled, 0 fee
1721                 //
1722                 // chan6  1-to-2: enabled, 0 fee
1723                 // chan6  2-to-1: enabled, 0 fee
1724                 //
1725                 // chan7  1-to-2: enabled, 100% fee
1726                 // chan7  2-to-1: enabled, 0 fee
1727                 //
1728                 // chan8  1-to-2: enabled, variable fee (0 then 1000 msat)
1729                 // chan8  2-to-1: enabled, 0 fee
1730                 //
1731                 // chan9  1-to-2: enabled, 1001 msat fee
1732                 // chan9  2-to-1: enabled, 0 fee
1733                 //
1734                 // chan10 1-to-2: enabled, 0 fee
1735                 // chan10 2-to-1: enabled, 0 fee
1736                 //
1737                 // chan11 1-to-2: enabled, 0 fee
1738                 // chan11 2-to-1: enabled, 0 fee
1739
1740                 let (our_privkey, _, privkeys, _) = get_nodes(&secp_ctx);
1741
1742                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[0], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
1743                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1744                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1745                         short_channel_id: 1,
1746                         timestamp: 1,
1747                         flags: 1,
1748                         cltv_expiry_delta: 0,
1749                         htlc_minimum_msat: 0,
1750                         htlc_maximum_msat: OptionalField::Absent,
1751                         fee_base_msat: 0,
1752                         fee_proportional_millionths: 0,
1753                         excess_data: Vec::new()
1754                 });
1755
1756                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
1757
1758                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
1759                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1760                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1761                         short_channel_id: 2,
1762                         timestamp: 1,
1763                         flags: 0,
1764                         cltv_expiry_delta: (5 << 4) | 3,
1765                         htlc_minimum_msat: 0,
1766                         htlc_maximum_msat: OptionalField::Absent,
1767                         fee_base_msat: u32::max_value(),
1768                         fee_proportional_millionths: u32::max_value(),
1769                         excess_data: Vec::new()
1770                 });
1771                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1772                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1773                         short_channel_id: 2,
1774                         timestamp: 1,
1775                         flags: 1,
1776                         cltv_expiry_delta: 0,
1777                         htlc_minimum_msat: 0,
1778                         htlc_maximum_msat: OptionalField::Absent,
1779                         fee_base_msat: 0,
1780                         fee_proportional_millionths: 0,
1781                         excess_data: Vec::new()
1782                 });
1783
1784                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
1785
1786                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[7], ChannelFeatures::from_le_bytes(id_to_feature_flags(12)), 12);
1787                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1788                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1789                         short_channel_id: 12,
1790                         timestamp: 1,
1791                         flags: 0,
1792                         cltv_expiry_delta: (5 << 4) | 3,
1793                         htlc_minimum_msat: 0,
1794                         htlc_maximum_msat: OptionalField::Absent,
1795                         fee_base_msat: u32::max_value(),
1796                         fee_proportional_millionths: u32::max_value(),
1797                         excess_data: Vec::new()
1798                 });
1799                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1800                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1801                         short_channel_id: 12,
1802                         timestamp: 1,
1803                         flags: 1,
1804                         cltv_expiry_delta: 0,
1805                         htlc_minimum_msat: 0,
1806                         htlc_maximum_msat: OptionalField::Absent,
1807                         fee_base_msat: 0,
1808                         fee_proportional_millionths: 0,
1809                         excess_data: Vec::new()
1810                 });
1811
1812                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], NodeFeatures::from_le_bytes(id_to_feature_flags(8)), 0);
1813
1814                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
1815                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1816                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1817                         short_channel_id: 3,
1818                         timestamp: 1,
1819                         flags: 0,
1820                         cltv_expiry_delta: (3 << 4) | 1,
1821                         htlc_minimum_msat: 0,
1822                         htlc_maximum_msat: OptionalField::Absent,
1823                         fee_base_msat: 0,
1824                         fee_proportional_millionths: 0,
1825                         excess_data: Vec::new()
1826                 });
1827                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1828                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1829                         short_channel_id: 3,
1830                         timestamp: 1,
1831                         flags: 1,
1832                         cltv_expiry_delta: (3 << 4) | 2,
1833                         htlc_minimum_msat: 0,
1834                         htlc_maximum_msat: OptionalField::Absent,
1835                         fee_base_msat: 100,
1836                         fee_proportional_millionths: 0,
1837                         excess_data: Vec::new()
1838                 });
1839
1840                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
1841                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1842                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1843                         short_channel_id: 4,
1844                         timestamp: 1,
1845                         flags: 0,
1846                         cltv_expiry_delta: (4 << 4) | 1,
1847                         htlc_minimum_msat: 0,
1848                         htlc_maximum_msat: OptionalField::Absent,
1849                         fee_base_msat: 0,
1850                         fee_proportional_millionths: 1000000,
1851                         excess_data: Vec::new()
1852                 });
1853                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1854                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1855                         short_channel_id: 4,
1856                         timestamp: 1,
1857                         flags: 1,
1858                         cltv_expiry_delta: (4 << 4) | 2,
1859                         htlc_minimum_msat: 0,
1860                         htlc_maximum_msat: OptionalField::Absent,
1861                         fee_base_msat: 0,
1862                         fee_proportional_millionths: 0,
1863                         excess_data: Vec::new()
1864                 });
1865
1866                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(13)), 13);
1867                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1868                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1869                         short_channel_id: 13,
1870                         timestamp: 1,
1871                         flags: 0,
1872                         cltv_expiry_delta: (13 << 4) | 1,
1873                         htlc_minimum_msat: 0,
1874                         htlc_maximum_msat: OptionalField::Absent,
1875                         fee_base_msat: 0,
1876                         fee_proportional_millionths: 2000000,
1877                         excess_data: Vec::new()
1878                 });
1879                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1880                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1881                         short_channel_id: 13,
1882                         timestamp: 1,
1883                         flags: 1,
1884                         cltv_expiry_delta: (13 << 4) | 2,
1885                         htlc_minimum_msat: 0,
1886                         htlc_maximum_msat: OptionalField::Absent,
1887                         fee_base_msat: 0,
1888                         fee_proportional_millionths: 0,
1889                         excess_data: Vec::new()
1890                 });
1891
1892                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
1893
1894                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
1895                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1896                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1897                         short_channel_id: 6,
1898                         timestamp: 1,
1899                         flags: 0,
1900                         cltv_expiry_delta: (6 << 4) | 1,
1901                         htlc_minimum_msat: 0,
1902                         htlc_maximum_msat: OptionalField::Absent,
1903                         fee_base_msat: 0,
1904                         fee_proportional_millionths: 0,
1905                         excess_data: Vec::new()
1906                 });
1907                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1908                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1909                         short_channel_id: 6,
1910                         timestamp: 1,
1911                         flags: 1,
1912                         cltv_expiry_delta: (6 << 4) | 2,
1913                         htlc_minimum_msat: 0,
1914                         htlc_maximum_msat: OptionalField::Absent,
1915                         fee_base_msat: 0,
1916                         fee_proportional_millionths: 0,
1917                         excess_data: Vec::new(),
1918                 });
1919
1920                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(11)), 11);
1921                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1922                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1923                         short_channel_id: 11,
1924                         timestamp: 1,
1925                         flags: 0,
1926                         cltv_expiry_delta: (11 << 4) | 1,
1927                         htlc_minimum_msat: 0,
1928                         htlc_maximum_msat: OptionalField::Absent,
1929                         fee_base_msat: 0,
1930                         fee_proportional_millionths: 0,
1931                         excess_data: Vec::new()
1932                 });
1933                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
1934                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1935                         short_channel_id: 11,
1936                         timestamp: 1,
1937                         flags: 1,
1938                         cltv_expiry_delta: (11 << 4) | 2,
1939                         htlc_minimum_msat: 0,
1940                         htlc_maximum_msat: OptionalField::Absent,
1941                         fee_base_msat: 0,
1942                         fee_proportional_millionths: 0,
1943                         excess_data: Vec::new()
1944                 });
1945
1946                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(5)), 0);
1947
1948                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
1949
1950                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[5], ChannelFeatures::from_le_bytes(id_to_feature_flags(7)), 7);
1951                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1952                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1953                         short_channel_id: 7,
1954                         timestamp: 1,
1955                         flags: 0,
1956                         cltv_expiry_delta: (7 << 4) | 1,
1957                         htlc_minimum_msat: 0,
1958                         htlc_maximum_msat: OptionalField::Absent,
1959                         fee_base_msat: 0,
1960                         fee_proportional_millionths: 1000000,
1961                         excess_data: Vec::new()
1962                 });
1963                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[5], UnsignedChannelUpdate {
1964                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1965                         short_channel_id: 7,
1966                         timestamp: 1,
1967                         flags: 1,
1968                         cltv_expiry_delta: (7 << 4) | 2,
1969                         htlc_minimum_msat: 0,
1970                         htlc_maximum_msat: OptionalField::Absent,
1971                         fee_base_msat: 0,
1972                         fee_proportional_millionths: 0,
1973                         excess_data: Vec::new()
1974                 });
1975
1976                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[5], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
1977
1978                 (secp_ctx, network_graph, net_graph_msg_handler, chain_monitor, logger)
1979         }
1980
1981         #[test]
1982         fn simple_route_test() {
1983                 let (secp_ctx, network_graph, _, _, logger) = build_graph();
1984                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1985                 let payment_params = PaymentParameters::from_node_id(nodes[2]);
1986                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
1987
1988                 // Simple route to 2 via 1
1989
1990                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &payment_params, &network_graph, None, 0, 42, Arc::clone(&logger), &scorer) {
1991                         assert_eq!(err, "Cannot send a payment of 0 msat");
1992                 } else { panic!(); }
1993
1994                 let route = get_route(&our_id, &payment_params, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
1995                 assert_eq!(route.paths[0].len(), 2);
1996
1997                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
1998                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1999                 assert_eq!(route.paths[0][0].fee_msat, 100);
2000                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 4) | 1);
2001                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2002                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2003
2004                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2005                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2006                 assert_eq!(route.paths[0][1].fee_msat, 100);
2007                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2008                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2009                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2010         }
2011
2012         #[test]
2013         fn invalid_first_hop_test() {
2014                 let (secp_ctx, network_graph, _, _, logger) = build_graph();
2015                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2016                 let payment_params = PaymentParameters::from_node_id(nodes[2]);
2017                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2018
2019                 // Simple route to 2 via 1
2020
2021                 let our_chans = vec![get_channel_details(Some(2), our_id, InitFeatures::from_le_bytes(vec![0b11]), 100000)];
2022
2023                 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) {
2024                         assert_eq!(err, "First hop cannot have our_node_pubkey as a destination.");
2025                 } else { panic!(); }
2026
2027                 let route = get_route(&our_id, &payment_params, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
2028                 assert_eq!(route.paths[0].len(), 2);
2029         }
2030
2031         #[test]
2032         fn htlc_minimum_test() {
2033                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
2034                 let (our_privkey, our_id, privkeys, 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                 // Disable other paths
2041                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2042                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2043                         short_channel_id: 12,
2044                         timestamp: 2,
2045                         flags: 2, // to disable
2046                         cltv_expiry_delta: 0,
2047                         htlc_minimum_msat: 0,
2048                         htlc_maximum_msat: OptionalField::Absent,
2049                         fee_base_msat: 0,
2050                         fee_proportional_millionths: 0,
2051                         excess_data: Vec::new()
2052                 });
2053                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2054                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2055                         short_channel_id: 3,
2056                         timestamp: 2,
2057                         flags: 2, // to disable
2058                         cltv_expiry_delta: 0,
2059                         htlc_minimum_msat: 0,
2060                         htlc_maximum_msat: OptionalField::Absent,
2061                         fee_base_msat: 0,
2062                         fee_proportional_millionths: 0,
2063                         excess_data: Vec::new()
2064                 });
2065                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2066                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2067                         short_channel_id: 13,
2068                         timestamp: 2,
2069                         flags: 2, // to disable
2070                         cltv_expiry_delta: 0,
2071                         htlc_minimum_msat: 0,
2072                         htlc_maximum_msat: OptionalField::Absent,
2073                         fee_base_msat: 0,
2074                         fee_proportional_millionths: 0,
2075                         excess_data: Vec::new()
2076                 });
2077                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2078                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2079                         short_channel_id: 6,
2080                         timestamp: 2,
2081                         flags: 2, // to disable
2082                         cltv_expiry_delta: 0,
2083                         htlc_minimum_msat: 0,
2084                         htlc_maximum_msat: OptionalField::Absent,
2085                         fee_base_msat: 0,
2086                         fee_proportional_millionths: 0,
2087                         excess_data: Vec::new()
2088                 });
2089                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2090                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2091                         short_channel_id: 7,
2092                         timestamp: 2,
2093                         flags: 2, // to disable
2094                         cltv_expiry_delta: 0,
2095                         htlc_minimum_msat: 0,
2096                         htlc_maximum_msat: OptionalField::Absent,
2097                         fee_base_msat: 0,
2098                         fee_proportional_millionths: 0,
2099                         excess_data: Vec::new()
2100                 });
2101
2102                 // Check against amount_to_transfer_over_msat.
2103                 // Set minimal HTLC of 200_000_000 msat.
2104                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2105                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2106                         short_channel_id: 2,
2107                         timestamp: 3,
2108                         flags: 0,
2109                         cltv_expiry_delta: 0,
2110                         htlc_minimum_msat: 200_000_000,
2111                         htlc_maximum_msat: OptionalField::Absent,
2112                         fee_base_msat: 0,
2113                         fee_proportional_millionths: 0,
2114                         excess_data: Vec::new()
2115                 });
2116
2117                 // Second hop only allows to forward 199_999_999 at most, thus not allowing the first hop to
2118                 // be used.
2119                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2120                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2121                         short_channel_id: 4,
2122                         timestamp: 3,
2123                         flags: 0,
2124                         cltv_expiry_delta: 0,
2125                         htlc_minimum_msat: 0,
2126                         htlc_maximum_msat: OptionalField::Present(199_999_999),
2127                         fee_base_msat: 0,
2128                         fee_proportional_millionths: 0,
2129                         excess_data: Vec::new()
2130                 });
2131
2132                 // Not possible to send 199_999_999, because the minimum on channel=2 is 200_000_000.
2133                 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) {
2134                         assert_eq!(err, "Failed to find a path to the given destination");
2135                 } else { panic!(); }
2136
2137                 // Lift the restriction on the first hop.
2138                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2139                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2140                         short_channel_id: 2,
2141                         timestamp: 4,
2142                         flags: 0,
2143                         cltv_expiry_delta: 0,
2144                         htlc_minimum_msat: 0,
2145                         htlc_maximum_msat: OptionalField::Absent,
2146                         fee_base_msat: 0,
2147                         fee_proportional_millionths: 0,
2148                         excess_data: Vec::new()
2149                 });
2150
2151                 // A payment above the minimum should pass
2152                 let route = get_route(&our_id, &payment_params, &network_graph, None, 199_999_999, 42, Arc::clone(&logger), &scorer).unwrap();
2153                 assert_eq!(route.paths[0].len(), 2);
2154         }
2155
2156         #[test]
2157         fn htlc_minimum_overpay_test() {
2158                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
2159                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2160                 let payment_params = PaymentParameters::from_node_id(nodes[2]).with_features(InvoiceFeatures::known());
2161                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2162
2163                 // A route to node#2 via two paths.
2164                 // One path allows transferring 35-40 sats, another one also allows 35-40 sats.
2165                 // Thus, they can't send 60 without overpaying.
2166                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2167                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2168                         short_channel_id: 2,
2169                         timestamp: 2,
2170                         flags: 0,
2171                         cltv_expiry_delta: 0,
2172                         htlc_minimum_msat: 35_000,
2173                         htlc_maximum_msat: OptionalField::Present(40_000),
2174                         fee_base_msat: 0,
2175                         fee_proportional_millionths: 0,
2176                         excess_data: Vec::new()
2177                 });
2178                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2179                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2180                         short_channel_id: 12,
2181                         timestamp: 3,
2182                         flags: 0,
2183                         cltv_expiry_delta: 0,
2184                         htlc_minimum_msat: 35_000,
2185                         htlc_maximum_msat: OptionalField::Present(40_000),
2186                         fee_base_msat: 0,
2187                         fee_proportional_millionths: 0,
2188                         excess_data: Vec::new()
2189                 });
2190
2191                 // Make 0 fee.
2192                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2193                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2194                         short_channel_id: 13,
2195                         timestamp: 2,
2196                         flags: 0,
2197                         cltv_expiry_delta: 0,
2198                         htlc_minimum_msat: 0,
2199                         htlc_maximum_msat: OptionalField::Absent,
2200                         fee_base_msat: 0,
2201                         fee_proportional_millionths: 0,
2202                         excess_data: Vec::new()
2203                 });
2204                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2205                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2206                         short_channel_id: 4,
2207                         timestamp: 2,
2208                         flags: 0,
2209                         cltv_expiry_delta: 0,
2210                         htlc_minimum_msat: 0,
2211                         htlc_maximum_msat: OptionalField::Absent,
2212                         fee_base_msat: 0,
2213                         fee_proportional_millionths: 0,
2214                         excess_data: Vec::new()
2215                 });
2216
2217                 // Disable other paths
2218                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2219                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2220                         short_channel_id: 1,
2221                         timestamp: 3,
2222                         flags: 2, // to disable
2223                         cltv_expiry_delta: 0,
2224                         htlc_minimum_msat: 0,
2225                         htlc_maximum_msat: OptionalField::Absent,
2226                         fee_base_msat: 0,
2227                         fee_proportional_millionths: 0,
2228                         excess_data: Vec::new()
2229                 });
2230
2231                 let route = get_route(&our_id, &payment_params, &network_graph, None, 60_000, 42, Arc::clone(&logger), &scorer).unwrap();
2232                 // Overpay fees to hit htlc_minimum_msat.
2233                 let overpaid_fees = route.paths[0][0].fee_msat + route.paths[1][0].fee_msat;
2234                 // TODO: this could be better balanced to overpay 10k and not 15k.
2235                 assert_eq!(overpaid_fees, 15_000);
2236
2237                 // Now, test that if there are 2 paths, a "cheaper" by fee path wouldn't be prioritized
2238                 // while taking even more fee to match htlc_minimum_msat.
2239                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2240                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2241                         short_channel_id: 12,
2242                         timestamp: 4,
2243                         flags: 0,
2244                         cltv_expiry_delta: 0,
2245                         htlc_minimum_msat: 65_000,
2246                         htlc_maximum_msat: OptionalField::Present(80_000),
2247                         fee_base_msat: 0,
2248                         fee_proportional_millionths: 0,
2249                         excess_data: Vec::new()
2250                 });
2251                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2252                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2253                         short_channel_id: 2,
2254                         timestamp: 3,
2255                         flags: 0,
2256                         cltv_expiry_delta: 0,
2257                         htlc_minimum_msat: 0,
2258                         htlc_maximum_msat: OptionalField::Absent,
2259                         fee_base_msat: 0,
2260                         fee_proportional_millionths: 0,
2261                         excess_data: Vec::new()
2262                 });
2263                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2264                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2265                         short_channel_id: 4,
2266                         timestamp: 4,
2267                         flags: 0,
2268                         cltv_expiry_delta: 0,
2269                         htlc_minimum_msat: 0,
2270                         htlc_maximum_msat: OptionalField::Absent,
2271                         fee_base_msat: 0,
2272                         fee_proportional_millionths: 100_000,
2273                         excess_data: Vec::new()
2274                 });
2275
2276                 let route = get_route(&our_id, &payment_params, &network_graph, None, 60_000, 42, Arc::clone(&logger), &scorer).unwrap();
2277                 // Fine to overpay for htlc_minimum_msat if it allows us to save fee.
2278                 assert_eq!(route.paths.len(), 1);
2279                 assert_eq!(route.paths[0][0].short_channel_id, 12);
2280                 let fees = route.paths[0][0].fee_msat;
2281                 assert_eq!(fees, 5_000);
2282
2283                 let route = get_route(&our_id, &payment_params, &network_graph, None, 50_000, 42, Arc::clone(&logger), &scorer).unwrap();
2284                 // Not fine to overpay for htlc_minimum_msat if it requires paying more than fee on
2285                 // the other channel.
2286                 assert_eq!(route.paths.len(), 1);
2287                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2288                 let fees = route.paths[0][0].fee_msat;
2289                 assert_eq!(fees, 5_000);
2290         }
2291
2292         #[test]
2293         fn disable_channels_test() {
2294                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
2295                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2296                 let payment_params = PaymentParameters::from_node_id(nodes[2]);
2297                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2298
2299                 // // Disable channels 4 and 12 by flags=2
2300                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2301                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2302                         short_channel_id: 4,
2303                         timestamp: 2,
2304                         flags: 2, // to disable
2305                         cltv_expiry_delta: 0,
2306                         htlc_minimum_msat: 0,
2307                         htlc_maximum_msat: OptionalField::Absent,
2308                         fee_base_msat: 0,
2309                         fee_proportional_millionths: 0,
2310                         excess_data: Vec::new()
2311                 });
2312                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2313                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2314                         short_channel_id: 12,
2315                         timestamp: 2,
2316                         flags: 2, // to disable
2317                         cltv_expiry_delta: 0,
2318                         htlc_minimum_msat: 0,
2319                         htlc_maximum_msat: OptionalField::Absent,
2320                         fee_base_msat: 0,
2321                         fee_proportional_millionths: 0,
2322                         excess_data: Vec::new()
2323                 });
2324
2325                 // If all the channels require some features we don't understand, route should fail
2326                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &payment_params, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer) {
2327                         assert_eq!(err, "Failed to find a path to the given destination");
2328                 } else { panic!(); }
2329
2330                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2331                 let our_chans = vec![get_channel_details(Some(42), nodes[7].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2332                 let route = get_route(&our_id, &payment_params, &network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 100, 42, Arc::clone(&logger), &scorer).unwrap();
2333                 assert_eq!(route.paths[0].len(), 2);
2334
2335                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2336                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2337                 assert_eq!(route.paths[0][0].fee_msat, 200);
2338                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 4) | 1);
2339                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
2340                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2341
2342                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2343                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2344                 assert_eq!(route.paths[0][1].fee_msat, 100);
2345                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2346                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2347                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2348         }
2349
2350         #[test]
2351         fn disable_node_test() {
2352                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
2353                 let (_, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2354                 let payment_params = PaymentParameters::from_node_id(nodes[2]);
2355                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2356
2357                 // Disable nodes 1, 2, and 8 by requiring unknown feature bits
2358                 let unknown_features = NodeFeatures::known().set_unknown_feature_required();
2359                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], unknown_features.clone(), 1);
2360                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], unknown_features.clone(), 1);
2361                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], unknown_features.clone(), 1);
2362
2363                 // If all nodes require some features we don't understand, route should fail
2364                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &payment_params, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer) {
2365                         assert_eq!(err, "Failed to find a path to the given destination");
2366                 } else { panic!(); }
2367
2368                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2369                 let our_chans = vec![get_channel_details(Some(42), nodes[7].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2370                 let route = get_route(&our_id, &payment_params, &network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 100, 42, Arc::clone(&logger), &scorer).unwrap();
2371                 assert_eq!(route.paths[0].len(), 2);
2372
2373                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2374                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2375                 assert_eq!(route.paths[0][0].fee_msat, 200);
2376                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 4) | 1);
2377                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
2378                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2379
2380                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2381                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2382                 assert_eq!(route.paths[0][1].fee_msat, 100);
2383                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2384                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2385                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2386
2387                 // Note that we don't test disabling node 3 and failing to route to it, as we (somewhat
2388                 // naively) assume that the user checked the feature bits on the invoice, which override
2389                 // the node_announcement.
2390         }
2391
2392         #[test]
2393         fn our_chans_test() {
2394                 let (secp_ctx, network_graph, _, _, logger) = build_graph();
2395                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2396                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2397
2398                 // Route to 1 via 2 and 3 because our channel to 1 is disabled
2399                 let payment_params = PaymentParameters::from_node_id(nodes[0]);
2400                 let route = get_route(&our_id, &payment_params, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
2401                 assert_eq!(route.paths[0].len(), 3);
2402
2403                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2404                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2405                 assert_eq!(route.paths[0][0].fee_msat, 200);
2406                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 4) | 1);
2407                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2408                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2409
2410                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2411                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2412                 assert_eq!(route.paths[0][1].fee_msat, 100);
2413                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (3 << 4) | 2);
2414                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2415                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2416
2417                 assert_eq!(route.paths[0][2].pubkey, nodes[0]);
2418                 assert_eq!(route.paths[0][2].short_channel_id, 3);
2419                 assert_eq!(route.paths[0][2].fee_msat, 100);
2420                 assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
2421                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(1));
2422                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(3));
2423
2424                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2425                 let payment_params = PaymentParameters::from_node_id(nodes[2]);
2426                 let our_chans = vec![get_channel_details(Some(42), nodes[7].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2427                 let route = get_route(&our_id, &payment_params, &network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 100, 42, Arc::clone(&logger), &scorer).unwrap();
2428                 assert_eq!(route.paths[0].len(), 2);
2429
2430                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2431                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2432                 assert_eq!(route.paths[0][0].fee_msat, 200);
2433                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 4) | 1);
2434                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2435                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2436
2437                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2438                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2439                 assert_eq!(route.paths[0][1].fee_msat, 100);
2440                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2441                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2442                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2443         }
2444
2445         fn last_hops(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2446                 let zero_fees = RoutingFees {
2447                         base_msat: 0,
2448                         proportional_millionths: 0,
2449                 };
2450                 vec![RouteHint(vec![RouteHintHop {
2451                         src_node_id: nodes[3],
2452                         short_channel_id: 8,
2453                         fees: zero_fees,
2454                         cltv_expiry_delta: (8 << 4) | 1,
2455                         htlc_minimum_msat: None,
2456                         htlc_maximum_msat: None,
2457                 }
2458                 ]), RouteHint(vec![RouteHintHop {
2459                         src_node_id: nodes[4],
2460                         short_channel_id: 9,
2461                         fees: RoutingFees {
2462                                 base_msat: 1001,
2463                                 proportional_millionths: 0,
2464                         },
2465                         cltv_expiry_delta: (9 << 4) | 1,
2466                         htlc_minimum_msat: None,
2467                         htlc_maximum_msat: None,
2468                 }]), RouteHint(vec![RouteHintHop {
2469                         src_node_id: nodes[5],
2470                         short_channel_id: 10,
2471                         fees: zero_fees,
2472                         cltv_expiry_delta: (10 << 4) | 1,
2473                         htlc_minimum_msat: None,
2474                         htlc_maximum_msat: None,
2475                 }])]
2476         }
2477
2478         fn last_hops_multi_private_channels(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2479                 let zero_fees = RoutingFees {
2480                         base_msat: 0,
2481                         proportional_millionths: 0,
2482                 };
2483                 vec![RouteHint(vec![RouteHintHop {
2484                         src_node_id: nodes[2],
2485                         short_channel_id: 5,
2486                         fees: RoutingFees {
2487                                 base_msat: 100,
2488                                 proportional_millionths: 0,
2489                         },
2490                         cltv_expiry_delta: (5 << 4) | 1,
2491                         htlc_minimum_msat: None,
2492                         htlc_maximum_msat: None,
2493                 }, RouteHintHop {
2494                         src_node_id: nodes[3],
2495                         short_channel_id: 8,
2496                         fees: zero_fees,
2497                         cltv_expiry_delta: (8 << 4) | 1,
2498                         htlc_minimum_msat: None,
2499                         htlc_maximum_msat: None,
2500                 }
2501                 ]), RouteHint(vec![RouteHintHop {
2502                         src_node_id: nodes[4],
2503                         short_channel_id: 9,
2504                         fees: RoutingFees {
2505                                 base_msat: 1001,
2506                                 proportional_millionths: 0,
2507                         },
2508                         cltv_expiry_delta: (9 << 4) | 1,
2509                         htlc_minimum_msat: None,
2510                         htlc_maximum_msat: None,
2511                 }]), RouteHint(vec![RouteHintHop {
2512                         src_node_id: nodes[5],
2513                         short_channel_id: 10,
2514                         fees: zero_fees,
2515                         cltv_expiry_delta: (10 << 4) | 1,
2516                         htlc_minimum_msat: None,
2517                         htlc_maximum_msat: None,
2518                 }])]
2519         }
2520
2521         #[test]
2522         fn partial_route_hint_test() {
2523                 let (secp_ctx, network_graph, _, _, logger) = build_graph();
2524                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2525                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2526
2527                 // Simple test across 2, 3, 5, and 4 via a last_hop channel
2528                 // Tests the behaviour when the RouteHint contains a suboptimal hop.
2529                 // RouteHint may be partially used by the algo to build the best path.
2530
2531                 // First check that last hop can't have its source as the payee.
2532                 let invalid_last_hop = RouteHint(vec![RouteHintHop {
2533                         src_node_id: nodes[6],
2534                         short_channel_id: 8,
2535                         fees: RoutingFees {
2536                                 base_msat: 1000,
2537                                 proportional_millionths: 0,
2538                         },
2539                         cltv_expiry_delta: (8 << 4) | 1,
2540                         htlc_minimum_msat: None,
2541                         htlc_maximum_msat: None,
2542                 }]);
2543
2544                 let mut invalid_last_hops = last_hops_multi_private_channels(&nodes);
2545                 invalid_last_hops.push(invalid_last_hop);
2546                 {
2547                         let payment_params = PaymentParameters::from_node_id(nodes[6]).with_route_hints(invalid_last_hops);
2548                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &payment_params, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer) {
2549                                 assert_eq!(err, "Route hint cannot have the payee as the source.");
2550                         } else { panic!(); }
2551                 }
2552
2553                 let payment_params = PaymentParameters::from_node_id(nodes[6]).with_route_hints(last_hops_multi_private_channels(&nodes));
2554                 let route = get_route(&our_id, &payment_params, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
2555                 assert_eq!(route.paths[0].len(), 5);
2556
2557                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2558                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2559                 assert_eq!(route.paths[0][0].fee_msat, 100);
2560                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 4) | 1);
2561                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2562                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2563
2564                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2565                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2566                 assert_eq!(route.paths[0][1].fee_msat, 0);
2567                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 4) | 1);
2568                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2569                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2570
2571                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2572                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2573                 assert_eq!(route.paths[0][2].fee_msat, 0);
2574                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 4) | 1);
2575                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2576                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2577
2578                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2579                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2580                 assert_eq!(route.paths[0][3].fee_msat, 0);
2581                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 4) | 1);
2582                 // If we have a peer in the node map, we'll use their features here since we don't have
2583                 // a way of figuring out their features from the invoice:
2584                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2585                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2586
2587                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2588                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2589                 assert_eq!(route.paths[0][4].fee_msat, 100);
2590                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2591                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2592                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2593         }
2594
2595         fn empty_last_hop(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2596                 let zero_fees = RoutingFees {
2597                         base_msat: 0,
2598                         proportional_millionths: 0,
2599                 };
2600                 vec![RouteHint(vec![RouteHintHop {
2601                         src_node_id: nodes[3],
2602                         short_channel_id: 8,
2603                         fees: zero_fees,
2604                         cltv_expiry_delta: (8 << 4) | 1,
2605                         htlc_minimum_msat: None,
2606                         htlc_maximum_msat: None,
2607                 }]), RouteHint(vec![
2608
2609                 ]), RouteHint(vec![RouteHintHop {
2610                         src_node_id: nodes[5],
2611                         short_channel_id: 10,
2612                         fees: zero_fees,
2613                         cltv_expiry_delta: (10 << 4) | 1,
2614                         htlc_minimum_msat: None,
2615                         htlc_maximum_msat: None,
2616                 }])]
2617         }
2618
2619         #[test]
2620         fn ignores_empty_last_hops_test() {
2621                 let (secp_ctx, network_graph, _, _, logger) = build_graph();
2622                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2623                 let payment_params = PaymentParameters::from_node_id(nodes[6]).with_route_hints(empty_last_hop(&nodes));
2624                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2625
2626                 // Test handling of an empty RouteHint passed in Invoice.
2627
2628                 let route = get_route(&our_id, &payment_params, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
2629                 assert_eq!(route.paths[0].len(), 5);
2630
2631                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2632                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2633                 assert_eq!(route.paths[0][0].fee_msat, 100);
2634                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 4) | 1);
2635                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2636                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2637
2638                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2639                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2640                 assert_eq!(route.paths[0][1].fee_msat, 0);
2641                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 4) | 1);
2642                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2643                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2644
2645                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2646                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2647                 assert_eq!(route.paths[0][2].fee_msat, 0);
2648                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 4) | 1);
2649                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2650                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2651
2652                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2653                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2654                 assert_eq!(route.paths[0][3].fee_msat, 0);
2655                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 4) | 1);
2656                 // If we have a peer in the node map, we'll use their features here since we don't have
2657                 // a way of figuring out their features from the invoice:
2658                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2659                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2660
2661                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2662                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2663                 assert_eq!(route.paths[0][4].fee_msat, 100);
2664                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2665                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2666                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2667         }
2668
2669         fn multi_hint_last_hops(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2670                 let zero_fees = RoutingFees {
2671                         base_msat: 0,
2672                         proportional_millionths: 0,
2673                 };
2674                 vec![RouteHint(vec![RouteHintHop {
2675                         src_node_id: nodes[2],
2676                         short_channel_id: 5,
2677                         fees: RoutingFees {
2678                                 base_msat: 100,
2679                                 proportional_millionths: 0,
2680                         },
2681                         cltv_expiry_delta: (5 << 4) | 1,
2682                         htlc_minimum_msat: None,
2683                         htlc_maximum_msat: None,
2684                 }, RouteHintHop {
2685                         src_node_id: nodes[3],
2686                         short_channel_id: 8,
2687                         fees: zero_fees,
2688                         cltv_expiry_delta: (8 << 4) | 1,
2689                         htlc_minimum_msat: None,
2690                         htlc_maximum_msat: None,
2691                 }]), RouteHint(vec![RouteHintHop {
2692                         src_node_id: nodes[5],
2693                         short_channel_id: 10,
2694                         fees: zero_fees,
2695                         cltv_expiry_delta: (10 << 4) | 1,
2696                         htlc_minimum_msat: None,
2697                         htlc_maximum_msat: None,
2698                 }])]
2699         }
2700
2701         #[test]
2702         fn multi_hint_last_hops_test() {
2703                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
2704                 let (_, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2705                 let payment_params = PaymentParameters::from_node_id(nodes[6]).with_route_hints(multi_hint_last_hops(&nodes));
2706                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2707                 // Test through channels 2, 3, 5, 8.
2708                 // Test shows that multiple hop hints are considered.
2709
2710                 // Disabling channels 6 & 7 by flags=2
2711                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2712                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2713                         short_channel_id: 6,
2714                         timestamp: 2,
2715                         flags: 2, // to disable
2716                         cltv_expiry_delta: 0,
2717                         htlc_minimum_msat: 0,
2718                         htlc_maximum_msat: OptionalField::Absent,
2719                         fee_base_msat: 0,
2720                         fee_proportional_millionths: 0,
2721                         excess_data: Vec::new()
2722                 });
2723                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2724                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2725                         short_channel_id: 7,
2726                         timestamp: 2,
2727                         flags: 2, // to disable
2728                         cltv_expiry_delta: 0,
2729                         htlc_minimum_msat: 0,
2730                         htlc_maximum_msat: OptionalField::Absent,
2731                         fee_base_msat: 0,
2732                         fee_proportional_millionths: 0,
2733                         excess_data: Vec::new()
2734                 });
2735
2736                 let route = get_route(&our_id, &payment_params, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
2737                 assert_eq!(route.paths[0].len(), 4);
2738
2739                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2740                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2741                 assert_eq!(route.paths[0][0].fee_msat, 200);
2742                 assert_eq!(route.paths[0][0].cltv_expiry_delta, 65);
2743                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2744                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2745
2746                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2747                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2748                 assert_eq!(route.paths[0][1].fee_msat, 100);
2749                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 81);
2750                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2751                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2752
2753                 assert_eq!(route.paths[0][2].pubkey, nodes[3]);
2754                 assert_eq!(route.paths[0][2].short_channel_id, 5);
2755                 assert_eq!(route.paths[0][2].fee_msat, 0);
2756                 assert_eq!(route.paths[0][2].cltv_expiry_delta, 129);
2757                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(4));
2758                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &Vec::<u8>::new());
2759
2760                 assert_eq!(route.paths[0][3].pubkey, nodes[6]);
2761                 assert_eq!(route.paths[0][3].short_channel_id, 8);
2762                 assert_eq!(route.paths[0][3].fee_msat, 100);
2763                 assert_eq!(route.paths[0][3].cltv_expiry_delta, 42);
2764                 assert_eq!(route.paths[0][3].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2765                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2766         }
2767
2768         fn last_hops_with_public_channel(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2769                 let zero_fees = RoutingFees {
2770                         base_msat: 0,
2771                         proportional_millionths: 0,
2772                 };
2773                 vec![RouteHint(vec![RouteHintHop {
2774                         src_node_id: nodes[4],
2775                         short_channel_id: 11,
2776                         fees: zero_fees,
2777                         cltv_expiry_delta: (11 << 4) | 1,
2778                         htlc_minimum_msat: None,
2779                         htlc_maximum_msat: None,
2780                 }, RouteHintHop {
2781                         src_node_id: nodes[3],
2782                         short_channel_id: 8,
2783                         fees: zero_fees,
2784                         cltv_expiry_delta: (8 << 4) | 1,
2785                         htlc_minimum_msat: None,
2786                         htlc_maximum_msat: None,
2787                 }]), RouteHint(vec![RouteHintHop {
2788                         src_node_id: nodes[4],
2789                         short_channel_id: 9,
2790                         fees: RoutingFees {
2791                                 base_msat: 1001,
2792                                 proportional_millionths: 0,
2793                         },
2794                         cltv_expiry_delta: (9 << 4) | 1,
2795                         htlc_minimum_msat: None,
2796                         htlc_maximum_msat: None,
2797                 }]), RouteHint(vec![RouteHintHop {
2798                         src_node_id: nodes[5],
2799                         short_channel_id: 10,
2800                         fees: zero_fees,
2801                         cltv_expiry_delta: (10 << 4) | 1,
2802                         htlc_minimum_msat: None,
2803                         htlc_maximum_msat: None,
2804                 }])]
2805         }
2806
2807         #[test]
2808         fn last_hops_with_public_channel_test() {
2809                 let (secp_ctx, network_graph, _, _, logger) = build_graph();
2810                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2811                 let payment_params = PaymentParameters::from_node_id(nodes[6]).with_route_hints(last_hops_with_public_channel(&nodes));
2812                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2813                 // This test shows that public routes can be present in the invoice
2814                 // which would be handled in the same manner.
2815
2816                 let route = get_route(&our_id, &payment_params, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
2817                 assert_eq!(route.paths[0].len(), 5);
2818
2819                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2820                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2821                 assert_eq!(route.paths[0][0].fee_msat, 100);
2822                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 4) | 1);
2823                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2824                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2825
2826                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2827                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2828                 assert_eq!(route.paths[0][1].fee_msat, 0);
2829                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 4) | 1);
2830                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2831                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2832
2833                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2834                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2835                 assert_eq!(route.paths[0][2].fee_msat, 0);
2836                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 4) | 1);
2837                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2838                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2839
2840                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2841                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2842                 assert_eq!(route.paths[0][3].fee_msat, 0);
2843                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 4) | 1);
2844                 // If we have a peer in the node map, we'll use their features here since we don't have
2845                 // a way of figuring out their features from the invoice:
2846                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2847                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new());
2848
2849                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2850                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2851                 assert_eq!(route.paths[0][4].fee_msat, 100);
2852                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2853                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2854                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2855         }
2856
2857         #[test]
2858         fn our_chans_last_hop_connect_test() {
2859                 let (secp_ctx, network_graph, _, _, logger) = build_graph();
2860                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2861                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2862
2863                 // Simple test with outbound channel to 4 to test that last_hops and first_hops connect
2864                 let our_chans = vec![get_channel_details(Some(42), nodes[3].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2865                 let mut last_hops = last_hops(&nodes);
2866                 let payment_params = PaymentParameters::from_node_id(nodes[6]).with_route_hints(last_hops.clone());
2867                 let route = get_route(&our_id, &payment_params, &network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 100, 42, Arc::clone(&logger), &scorer).unwrap();
2868                 assert_eq!(route.paths[0].len(), 2);
2869
2870                 assert_eq!(route.paths[0][0].pubkey, nodes[3]);
2871                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2872                 assert_eq!(route.paths[0][0].fee_msat, 0);
2873                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 4) | 1);
2874                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2875                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2876
2877                 assert_eq!(route.paths[0][1].pubkey, nodes[6]);
2878                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2879                 assert_eq!(route.paths[0][1].fee_msat, 100);
2880                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2881                 assert_eq!(route.paths[0][1].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2882                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2883
2884                 last_hops[0].0[0].fees.base_msat = 1000;
2885
2886                 // Revert to via 6 as the fee on 8 goes up
2887                 let payment_params = PaymentParameters::from_node_id(nodes[6]).with_route_hints(last_hops);
2888                 let route = get_route(&our_id, &payment_params, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
2889                 assert_eq!(route.paths[0].len(), 4);
2890
2891                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2892                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2893                 assert_eq!(route.paths[0][0].fee_msat, 200); // fee increased as its % of value transferred across node
2894                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 4) | 1);
2895                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2896                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2897
2898                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2899                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2900                 assert_eq!(route.paths[0][1].fee_msat, 100);
2901                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (7 << 4) | 1);
2902                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2903                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2904
2905                 assert_eq!(route.paths[0][2].pubkey, nodes[5]);
2906                 assert_eq!(route.paths[0][2].short_channel_id, 7);
2907                 assert_eq!(route.paths[0][2].fee_msat, 0);
2908                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (10 << 4) | 1);
2909                 // If we have a peer in the node map, we'll use their features here since we don't have
2910                 // a way of figuring out their features from the invoice:
2911                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
2912                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(7));
2913
2914                 assert_eq!(route.paths[0][3].pubkey, nodes[6]);
2915                 assert_eq!(route.paths[0][3].short_channel_id, 10);
2916                 assert_eq!(route.paths[0][3].fee_msat, 100);
2917                 assert_eq!(route.paths[0][3].cltv_expiry_delta, 42);
2918                 assert_eq!(route.paths[0][3].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2919                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2920
2921                 // ...but still use 8 for larger payments as 6 has a variable feerate
2922                 let route = get_route(&our_id, &payment_params, &network_graph, None, 2000, 42, Arc::clone(&logger), &scorer).unwrap();
2923                 assert_eq!(route.paths[0].len(), 5);
2924
2925                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2926                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2927                 assert_eq!(route.paths[0][0].fee_msat, 3000);
2928                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 4) | 1);
2929                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2930                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2931
2932                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2933                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2934                 assert_eq!(route.paths[0][1].fee_msat, 0);
2935                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 4) | 1);
2936                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2937                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2938
2939                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2940                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2941                 assert_eq!(route.paths[0][2].fee_msat, 0);
2942                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 4) | 1);
2943                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2944                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2945
2946                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2947                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2948                 assert_eq!(route.paths[0][3].fee_msat, 1000);
2949                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 4) | 1);
2950                 // If we have a peer in the node map, we'll use their features here since we don't have
2951                 // a way of figuring out their features from the invoice:
2952                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2953                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2954
2955                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2956                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2957                 assert_eq!(route.paths[0][4].fee_msat, 2000);
2958                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2959                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2960                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2961         }
2962
2963         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> {
2964                 let source_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 41).repeat(32)).unwrap()[..]).unwrap());
2965                 let middle_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 42).repeat(32)).unwrap()[..]).unwrap());
2966                 let target_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 43).repeat(32)).unwrap()[..]).unwrap());
2967
2968                 // If we specify a channel to a middle hop, that overrides our local channel view and that gets used
2969                 let last_hops = RouteHint(vec![RouteHintHop {
2970                         src_node_id: middle_node_id,
2971                         short_channel_id: 8,
2972                         fees: RoutingFees {
2973                                 base_msat: 1000,
2974                                 proportional_millionths: last_hop_fee_prop,
2975                         },
2976                         cltv_expiry_delta: (8 << 4) | 1,
2977                         htlc_minimum_msat: None,
2978                         htlc_maximum_msat: last_hop_htlc_max,
2979                 }]);
2980                 let payment_params = PaymentParameters::from_node_id(target_node_id).with_route_hints(vec![last_hops]);
2981                 let our_chans = vec![get_channel_details(Some(42), middle_node_id, InitFeatures::from_le_bytes(vec![0b11]), outbound_capacity_msat)];
2982                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
2983                 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)
2984         }
2985
2986         #[test]
2987         fn unannounced_path_test() {
2988                 // We should be able to send a payment to a destination without any help of a routing graph
2989                 // if we have a channel with a common counterparty that appears in the first and last hop
2990                 // hints.
2991                 let route = do_unannounced_path_test(None, 1, 2000000, 1000000).unwrap();
2992
2993                 let middle_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 42).repeat(32)).unwrap()[..]).unwrap());
2994                 let target_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 43).repeat(32)).unwrap()[..]).unwrap());
2995                 assert_eq!(route.paths[0].len(), 2);
2996
2997                 assert_eq!(route.paths[0][0].pubkey, middle_node_id);
2998                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2999                 assert_eq!(route.paths[0][0].fee_msat, 1001);
3000                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 4) | 1);
3001                 assert_eq!(route.paths[0][0].node_features.le_flags(), &[0b11]);
3002                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
3003
3004                 assert_eq!(route.paths[0][1].pubkey, target_node_id);
3005                 assert_eq!(route.paths[0][1].short_channel_id, 8);
3006                 assert_eq!(route.paths[0][1].fee_msat, 1000000);
3007                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
3008                 assert_eq!(route.paths[0][1].node_features.le_flags(), &[0; 0]); // We dont pass flags in from invoices yet
3009                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
3010         }
3011
3012         #[test]
3013         fn overflow_unannounced_path_test_liquidity_underflow() {
3014                 // Previously, when we had a last-hop hint connected directly to a first-hop channel, where
3015                 // the last-hop had a fee which overflowed a u64, we'd panic.
3016                 // This was due to us adding the first-hop from us unconditionally, causing us to think
3017                 // we'd built a path (as our node is in the "best candidate" set), when we had not.
3018                 // In this test, we previously hit a subtraction underflow due to having less available
3019                 // liquidity at the last hop than 0.
3020                 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());
3021         }
3022
3023         #[test]
3024         fn overflow_unannounced_path_test_feerate_overflow() {
3025                 // This tests for the same case as above, except instead of hitting a subtraction
3026                 // underflow, we hit a case where the fee charged at a hop overflowed.
3027                 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());
3028         }
3029
3030         #[test]
3031         fn available_amount_while_routing_test() {
3032                 // Tests whether we choose the correct available channel amount while routing.
3033
3034                 let (secp_ctx, network_graph, mut net_graph_msg_handler, chain_monitor, logger) = build_graph();
3035                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3036                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
3037                 let payment_params = PaymentParameters::from_node_id(nodes[2]).with_features(InvoiceFeatures::known());
3038
3039                 // We will use a simple single-path route from
3040                 // our node to node2 via node0: channels {1, 3}.
3041
3042                 // First disable all other paths.
3043                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3044                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3045                         short_channel_id: 2,
3046                         timestamp: 2,
3047                         flags: 2,
3048                         cltv_expiry_delta: 0,
3049                         htlc_minimum_msat: 0,
3050                         htlc_maximum_msat: OptionalField::Present(100_000),
3051                         fee_base_msat: 0,
3052                         fee_proportional_millionths: 0,
3053                         excess_data: Vec::new()
3054                 });
3055                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3056                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3057                         short_channel_id: 12,
3058                         timestamp: 2,
3059                         flags: 2,
3060                         cltv_expiry_delta: 0,
3061                         htlc_minimum_msat: 0,
3062                         htlc_maximum_msat: OptionalField::Present(100_000),
3063                         fee_base_msat: 0,
3064                         fee_proportional_millionths: 0,
3065                         excess_data: Vec::new()
3066                 });
3067
3068                 // Make the first channel (#1) very permissive,
3069                 // and we will be testing all limits on the second channel.
3070                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3071                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3072                         short_channel_id: 1,
3073                         timestamp: 2,
3074                         flags: 0,
3075                         cltv_expiry_delta: 0,
3076                         htlc_minimum_msat: 0,
3077                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
3078                         fee_base_msat: 0,
3079                         fee_proportional_millionths: 0,
3080                         excess_data: Vec::new()
3081                 });
3082
3083                 // First, let's see if routing works if we have absolutely no idea about the available amount.
3084                 // In this case, it should be set to 250_000 sats.
3085                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3086                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3087                         short_channel_id: 3,
3088                         timestamp: 2,
3089                         flags: 0,
3090                         cltv_expiry_delta: 0,
3091                         htlc_minimum_msat: 0,
3092                         htlc_maximum_msat: OptionalField::Absent,
3093                         fee_base_msat: 0,
3094                         fee_proportional_millionths: 0,
3095                         excess_data: Vec::new()
3096                 });
3097
3098                 {
3099                         // Attempt to route more than available results in a failure.
3100                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3101                                         &our_id, &payment_params, &network_graph, None, 250_000_001, 42, Arc::clone(&logger), &scorer) {
3102                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3103                         } else { panic!(); }
3104                 }
3105
3106                 {
3107                         // Now, attempt to route an exact amount we have should be fine.
3108                         let route = get_route(&our_id, &payment_params, &network_graph, None, 250_000_000, 42, Arc::clone(&logger), &scorer).unwrap();
3109                         assert_eq!(route.paths.len(), 1);
3110                         let path = route.paths.last().unwrap();
3111                         assert_eq!(path.len(), 2);
3112                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3113                         assert_eq!(path.last().unwrap().fee_msat, 250_000_000);
3114                 }
3115
3116                 // Check that setting outbound_capacity_msat in first_hops limits the channels.
3117                 // Disable channel #1 and use another first hop.
3118                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3119                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3120                         short_channel_id: 1,
3121                         timestamp: 3,
3122                         flags: 2,
3123                         cltv_expiry_delta: 0,
3124                         htlc_minimum_msat: 0,
3125                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
3126                         fee_base_msat: 0,
3127                         fee_proportional_millionths: 0,
3128                         excess_data: Vec::new()
3129                 });
3130
3131                 // Now, limit the first_hop by the outbound_capacity_msat of 200_000 sats.
3132                 let our_chans = vec![get_channel_details(Some(42), nodes[0].clone(), InitFeatures::from_le_bytes(vec![0b11]), 200_000_000)];
3133
3134                 {
3135                         // Attempt to route more than available results in a failure.
3136                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3137                                         &our_id, &payment_params, &network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 200_000_001, 42, Arc::clone(&logger), &scorer) {
3138                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3139                         } else { panic!(); }
3140                 }
3141
3142                 {
3143                         // Now, attempt to route an exact amount we have should be fine.
3144                         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();
3145                         assert_eq!(route.paths.len(), 1);
3146                         let path = route.paths.last().unwrap();
3147                         assert_eq!(path.len(), 2);
3148                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3149                         assert_eq!(path.last().unwrap().fee_msat, 200_000_000);
3150                 }
3151
3152                 // Enable channel #1 back.
3153                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3154                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3155                         short_channel_id: 1,
3156                         timestamp: 4,
3157                         flags: 0,
3158                         cltv_expiry_delta: 0,
3159                         htlc_minimum_msat: 0,
3160                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
3161                         fee_base_msat: 0,
3162                         fee_proportional_millionths: 0,
3163                         excess_data: Vec::new()
3164                 });
3165
3166
3167                 // Now let's see if routing works if we know only htlc_maximum_msat.
3168                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3169                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3170                         short_channel_id: 3,
3171                         timestamp: 3,
3172                         flags: 0,
3173                         cltv_expiry_delta: 0,
3174                         htlc_minimum_msat: 0,
3175                         htlc_maximum_msat: OptionalField::Present(15_000),
3176                         fee_base_msat: 0,
3177                         fee_proportional_millionths: 0,
3178                         excess_data: Vec::new()
3179                 });
3180
3181                 {
3182                         // Attempt to route more than available results in a failure.
3183                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3184                                         &our_id, &payment_params, &network_graph, None, 15_001, 42, Arc::clone(&logger), &scorer) {
3185                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3186                         } else { panic!(); }
3187                 }
3188
3189                 {
3190                         // Now, attempt to route an exact amount we have should be fine.
3191                         let route = get_route(&our_id, &payment_params, &network_graph, None, 15_000, 42, Arc::clone(&logger), &scorer).unwrap();
3192                         assert_eq!(route.paths.len(), 1);
3193                         let path = route.paths.last().unwrap();
3194                         assert_eq!(path.len(), 2);
3195                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3196                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
3197                 }
3198
3199                 // Now let's see if routing works if we know only capacity from the UTXO.
3200
3201                 // We can't change UTXO capacity on the fly, so we'll disable
3202                 // the existing channel and add another one with the capacity we need.
3203                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3204                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3205                         short_channel_id: 3,
3206                         timestamp: 4,
3207                         flags: 2,
3208                         cltv_expiry_delta: 0,
3209                         htlc_minimum_msat: 0,
3210                         htlc_maximum_msat: OptionalField::Absent,
3211                         fee_base_msat: 0,
3212                         fee_proportional_millionths: 0,
3213                         excess_data: Vec::new()
3214                 });
3215
3216                 let good_script = Builder::new().push_opcode(opcodes::all::OP_PUSHNUM_2)
3217                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[0]).serialize())
3218                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[2]).serialize())
3219                 .push_opcode(opcodes::all::OP_PUSHNUM_2)
3220                 .push_opcode(opcodes::all::OP_CHECKMULTISIG).into_script().to_v0_p2wsh();
3221
3222                 *chain_monitor.utxo_ret.lock().unwrap() = Ok(TxOut { value: 15, script_pubkey: good_script.clone() });
3223                 net_graph_msg_handler.add_chain_access(Some(chain_monitor));
3224
3225                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 333);
3226                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3227                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3228                         short_channel_id: 333,
3229                         timestamp: 1,
3230                         flags: 0,
3231                         cltv_expiry_delta: (3 << 4) | 1,
3232                         htlc_minimum_msat: 0,
3233                         htlc_maximum_msat: OptionalField::Absent,
3234                         fee_base_msat: 0,
3235                         fee_proportional_millionths: 0,
3236                         excess_data: Vec::new()
3237                 });
3238                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3239                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3240                         short_channel_id: 333,
3241                         timestamp: 1,
3242                         flags: 1,
3243                         cltv_expiry_delta: (3 << 4) | 2,
3244                         htlc_minimum_msat: 0,
3245                         htlc_maximum_msat: OptionalField::Absent,
3246                         fee_base_msat: 100,
3247                         fee_proportional_millionths: 0,
3248                         excess_data: Vec::new()
3249                 });
3250
3251                 {
3252                         // Attempt to route more than available results in a failure.
3253                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3254                                         &our_id, &payment_params, &network_graph, None, 15_001, 42, Arc::clone(&logger), &scorer) {
3255                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3256                         } else { panic!(); }
3257                 }
3258
3259                 {
3260                         // Now, attempt to route an exact amount we have should be fine.
3261                         let route = get_route(&our_id, &payment_params, &network_graph, None, 15_000, 42, Arc::clone(&logger), &scorer).unwrap();
3262                         assert_eq!(route.paths.len(), 1);
3263                         let path = route.paths.last().unwrap();
3264                         assert_eq!(path.len(), 2);
3265                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3266                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
3267                 }
3268
3269                 // Now let's see if routing chooses htlc_maximum_msat over UTXO capacity.
3270                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3271                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3272                         short_channel_id: 333,
3273                         timestamp: 6,
3274                         flags: 0,
3275                         cltv_expiry_delta: 0,
3276                         htlc_minimum_msat: 0,
3277                         htlc_maximum_msat: OptionalField::Present(10_000),
3278                         fee_base_msat: 0,
3279                         fee_proportional_millionths: 0,
3280                         excess_data: Vec::new()
3281                 });
3282
3283                 {
3284                         // Attempt to route more than available results in a failure.
3285                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3286                                         &our_id, &payment_params, &network_graph, None, 10_001, 42, Arc::clone(&logger), &scorer) {
3287                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3288                         } else { panic!(); }
3289                 }
3290
3291                 {
3292                         // Now, attempt to route an exact amount we have should be fine.
3293                         let route = get_route(&our_id, &payment_params, &network_graph, None, 10_000, 42, Arc::clone(&logger), &scorer).unwrap();
3294                         assert_eq!(route.paths.len(), 1);
3295                         let path = route.paths.last().unwrap();
3296                         assert_eq!(path.len(), 2);
3297                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3298                         assert_eq!(path.last().unwrap().fee_msat, 10_000);
3299                 }
3300         }
3301
3302         #[test]
3303         fn available_liquidity_last_hop_test() {
3304                 // Check that available liquidity properly limits the path even when only
3305                 // one of the latter hops is limited.
3306                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
3307                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3308                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
3309                 let payment_params = PaymentParameters::from_node_id(nodes[3]).with_features(InvoiceFeatures::known());
3310
3311                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3312                 // {12, 13, 11} have the capacities of 100, {6} has a capacity of 50.
3313                 // Total capacity: 50 sats.
3314
3315                 // Disable other potential paths.
3316                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3317                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3318                         short_channel_id: 2,
3319                         timestamp: 2,
3320                         flags: 2,
3321                         cltv_expiry_delta: 0,
3322                         htlc_minimum_msat: 0,
3323                         htlc_maximum_msat: OptionalField::Present(100_000),
3324                         fee_base_msat: 0,
3325                         fee_proportional_millionths: 0,
3326                         excess_data: Vec::new()
3327                 });
3328                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3329                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3330                         short_channel_id: 7,
3331                         timestamp: 2,
3332                         flags: 2,
3333                         cltv_expiry_delta: 0,
3334                         htlc_minimum_msat: 0,
3335                         htlc_maximum_msat: OptionalField::Present(100_000),
3336                         fee_base_msat: 0,
3337                         fee_proportional_millionths: 0,
3338                         excess_data: Vec::new()
3339                 });
3340
3341                 // Limit capacities
3342
3343                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3344                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3345                         short_channel_id: 12,
3346                         timestamp: 2,
3347                         flags: 0,
3348                         cltv_expiry_delta: 0,
3349                         htlc_minimum_msat: 0,
3350                         htlc_maximum_msat: OptionalField::Present(100_000),
3351                         fee_base_msat: 0,
3352                         fee_proportional_millionths: 0,
3353                         excess_data: Vec::new()
3354                 });
3355                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3356                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3357                         short_channel_id: 13,
3358                         timestamp: 2,
3359                         flags: 0,
3360                         cltv_expiry_delta: 0,
3361                         htlc_minimum_msat: 0,
3362                         htlc_maximum_msat: OptionalField::Present(100_000),
3363                         fee_base_msat: 0,
3364                         fee_proportional_millionths: 0,
3365                         excess_data: Vec::new()
3366                 });
3367
3368                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3369                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3370                         short_channel_id: 6,
3371                         timestamp: 2,
3372                         flags: 0,
3373                         cltv_expiry_delta: 0,
3374                         htlc_minimum_msat: 0,
3375                         htlc_maximum_msat: OptionalField::Present(50_000),
3376                         fee_base_msat: 0,
3377                         fee_proportional_millionths: 0,
3378                         excess_data: Vec::new()
3379                 });
3380                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3381                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3382                         short_channel_id: 11,
3383                         timestamp: 2,
3384                         flags: 0,
3385                         cltv_expiry_delta: 0,
3386                         htlc_minimum_msat: 0,
3387                         htlc_maximum_msat: OptionalField::Present(100_000),
3388                         fee_base_msat: 0,
3389                         fee_proportional_millionths: 0,
3390                         excess_data: Vec::new()
3391                 });
3392                 {
3393                         // Attempt to route more than available results in a failure.
3394                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3395                                         &our_id, &payment_params, &network_graph, None, 60_000, 42, Arc::clone(&logger), &scorer) {
3396                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3397                         } else { panic!(); }
3398                 }
3399
3400                 {
3401                         // Now, attempt to route 49 sats (just a bit below the capacity).
3402                         let route = get_route(&our_id, &payment_params, &network_graph, None, 49_000, 42, Arc::clone(&logger), &scorer).unwrap();
3403                         assert_eq!(route.paths.len(), 1);
3404                         let mut total_amount_paid_msat = 0;
3405                         for path in &route.paths {
3406                                 assert_eq!(path.len(), 4);
3407                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3408                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3409                         }
3410                         assert_eq!(total_amount_paid_msat, 49_000);
3411                 }
3412
3413                 {
3414                         // Attempt to route an exact amount is also fine
3415                         let route = get_route(&our_id, &payment_params, &network_graph, None, 50_000, 42, Arc::clone(&logger), &scorer).unwrap();
3416                         assert_eq!(route.paths.len(), 1);
3417                         let mut total_amount_paid_msat = 0;
3418                         for path in &route.paths {
3419                                 assert_eq!(path.len(), 4);
3420                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3421                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3422                         }
3423                         assert_eq!(total_amount_paid_msat, 50_000);
3424                 }
3425         }
3426
3427         #[test]
3428         fn ignore_fee_first_hop_test() {
3429                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
3430                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3431                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
3432                 let payment_params = PaymentParameters::from_node_id(nodes[2]);
3433
3434                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
3435                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3436                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3437                         short_channel_id: 1,
3438                         timestamp: 2,
3439                         flags: 0,
3440                         cltv_expiry_delta: 0,
3441                         htlc_minimum_msat: 0,
3442                         htlc_maximum_msat: OptionalField::Present(100_000),
3443                         fee_base_msat: 1_000_000,
3444                         fee_proportional_millionths: 0,
3445                         excess_data: Vec::new()
3446                 });
3447                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3448                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3449                         short_channel_id: 3,
3450                         timestamp: 2,
3451                         flags: 0,
3452                         cltv_expiry_delta: 0,
3453                         htlc_minimum_msat: 0,
3454                         htlc_maximum_msat: OptionalField::Present(50_000),
3455                         fee_base_msat: 0,
3456                         fee_proportional_millionths: 0,
3457                         excess_data: Vec::new()
3458                 });
3459
3460                 {
3461                         let route = get_route(&our_id, &payment_params, &network_graph, None, 50_000, 42, Arc::clone(&logger), &scorer).unwrap();
3462                         assert_eq!(route.paths.len(), 1);
3463                         let mut total_amount_paid_msat = 0;
3464                         for path in &route.paths {
3465                                 assert_eq!(path.len(), 2);
3466                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3467                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3468                         }
3469                         assert_eq!(total_amount_paid_msat, 50_000);
3470                 }
3471         }
3472
3473         #[test]
3474         fn simple_mpp_route_test() {
3475                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
3476                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3477                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
3478                 let payment_params = PaymentParameters::from_node_id(nodes[2]).with_features(InvoiceFeatures::known());
3479
3480                 // We need a route consisting of 3 paths:
3481                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
3482                 // To achieve this, the amount being transferred should be around
3483                 // the total capacity of these 3 paths.
3484
3485                 // First, we set limits on these (previously unlimited) channels.
3486                 // Their aggregate capacity will be 50 + 60 + 180 = 290 sats.
3487
3488                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
3489                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3490                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3491                         short_channel_id: 1,
3492                         timestamp: 2,
3493                         flags: 0,
3494                         cltv_expiry_delta: 0,
3495                         htlc_minimum_msat: 0,
3496                         htlc_maximum_msat: OptionalField::Present(100_000),
3497                         fee_base_msat: 0,
3498                         fee_proportional_millionths: 0,
3499                         excess_data: Vec::new()
3500                 });
3501                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3502                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3503                         short_channel_id: 3,
3504                         timestamp: 2,
3505                         flags: 0,
3506                         cltv_expiry_delta: 0,
3507                         htlc_minimum_msat: 0,
3508                         htlc_maximum_msat: OptionalField::Present(50_000),
3509                         fee_base_msat: 0,
3510                         fee_proportional_millionths: 0,
3511                         excess_data: Vec::new()
3512                 });
3513
3514                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats
3515                 // (total limit 60).
3516                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3517                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3518                         short_channel_id: 12,
3519                         timestamp: 2,
3520                         flags: 0,
3521                         cltv_expiry_delta: 0,
3522                         htlc_minimum_msat: 0,
3523                         htlc_maximum_msat: OptionalField::Present(60_000),
3524                         fee_base_msat: 0,
3525                         fee_proportional_millionths: 0,
3526                         excess_data: Vec::new()
3527                 });
3528                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3529                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3530                         short_channel_id: 13,
3531                         timestamp: 2,
3532                         flags: 0,
3533                         cltv_expiry_delta: 0,
3534                         htlc_minimum_msat: 0,
3535                         htlc_maximum_msat: OptionalField::Present(60_000),
3536                         fee_base_msat: 0,
3537                         fee_proportional_millionths: 0,
3538                         excess_data: Vec::new()
3539                 });
3540
3541                 // Path via node1 is channels {2, 4}. Limit them to 200 and 180 sats
3542                 // (total capacity 180 sats).
3543                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3544                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3545                         short_channel_id: 2,
3546                         timestamp: 2,
3547                         flags: 0,
3548                         cltv_expiry_delta: 0,
3549                         htlc_minimum_msat: 0,
3550                         htlc_maximum_msat: OptionalField::Present(200_000),
3551                         fee_base_msat: 0,
3552                         fee_proportional_millionths: 0,
3553                         excess_data: Vec::new()
3554                 });
3555                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3556                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3557                         short_channel_id: 4,
3558                         timestamp: 2,
3559                         flags: 0,
3560                         cltv_expiry_delta: 0,
3561                         htlc_minimum_msat: 0,
3562                         htlc_maximum_msat: OptionalField::Present(180_000),
3563                         fee_base_msat: 0,
3564                         fee_proportional_millionths: 0,
3565                         excess_data: Vec::new()
3566                 });
3567
3568                 {
3569                         // Attempt to route more than available results in a failure.
3570                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3571                                         &our_id, &payment_params, &network_graph, None, 300_000, 42, Arc::clone(&logger), &scorer) {
3572                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3573                         } else { panic!(); }
3574                 }
3575
3576                 {
3577                         // Now, attempt to route 250 sats (just a bit below the capacity).
3578                         // Our algorithm should provide us with these 3 paths.
3579                         let route = get_route(&our_id, &payment_params, &network_graph, None, 250_000, 42, Arc::clone(&logger), &scorer).unwrap();
3580                         assert_eq!(route.paths.len(), 3);
3581                         let mut total_amount_paid_msat = 0;
3582                         for path in &route.paths {
3583                                 assert_eq!(path.len(), 2);
3584                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3585                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3586                         }
3587                         assert_eq!(total_amount_paid_msat, 250_000);
3588                 }
3589
3590                 {
3591                         // Attempt to route an exact amount is also fine
3592                         let route = get_route(&our_id, &payment_params, &network_graph, None, 290_000, 42, Arc::clone(&logger), &scorer).unwrap();
3593                         assert_eq!(route.paths.len(), 3);
3594                         let mut total_amount_paid_msat = 0;
3595                         for path in &route.paths {
3596                                 assert_eq!(path.len(), 2);
3597                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3598                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3599                         }
3600                         assert_eq!(total_amount_paid_msat, 290_000);
3601                 }
3602         }
3603
3604         #[test]
3605         fn long_mpp_route_test() {
3606                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
3607                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3608                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
3609                 let payment_params = PaymentParameters::from_node_id(nodes[3]).with_features(InvoiceFeatures::known());
3610
3611                 // We need a route consisting of 3 paths:
3612                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
3613                 // Note that these paths overlap (channels 5, 12, 13).
3614                 // We will route 300 sats.
3615                 // Each path will have 100 sats capacity, those channels which
3616                 // are used twice will have 200 sats capacity.
3617
3618                 // Disable other potential paths.
3619                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3620                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3621                         short_channel_id: 2,
3622                         timestamp: 2,
3623                         flags: 2,
3624                         cltv_expiry_delta: 0,
3625                         htlc_minimum_msat: 0,
3626                         htlc_maximum_msat: OptionalField::Present(100_000),
3627                         fee_base_msat: 0,
3628                         fee_proportional_millionths: 0,
3629                         excess_data: Vec::new()
3630                 });
3631                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3632                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3633                         short_channel_id: 7,
3634                         timestamp: 2,
3635                         flags: 2,
3636                         cltv_expiry_delta: 0,
3637                         htlc_minimum_msat: 0,
3638                         htlc_maximum_msat: OptionalField::Present(100_000),
3639                         fee_base_msat: 0,
3640                         fee_proportional_millionths: 0,
3641                         excess_data: Vec::new()
3642                 });
3643
3644                 // Path via {node0, node2} is channels {1, 3, 5}.
3645                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3646                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3647                         short_channel_id: 1,
3648                         timestamp: 2,
3649                         flags: 0,
3650                         cltv_expiry_delta: 0,
3651                         htlc_minimum_msat: 0,
3652                         htlc_maximum_msat: OptionalField::Present(100_000),
3653                         fee_base_msat: 0,
3654                         fee_proportional_millionths: 0,
3655                         excess_data: Vec::new()
3656                 });
3657                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3658                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3659                         short_channel_id: 3,
3660                         timestamp: 2,
3661                         flags: 0,
3662                         cltv_expiry_delta: 0,
3663                         htlc_minimum_msat: 0,
3664                         htlc_maximum_msat: OptionalField::Present(100_000),
3665                         fee_base_msat: 0,
3666                         fee_proportional_millionths: 0,
3667                         excess_data: Vec::new()
3668                 });
3669
3670                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3671                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3672                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3673                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3674                         short_channel_id: 5,
3675                         timestamp: 2,
3676                         flags: 0,
3677                         cltv_expiry_delta: 0,
3678                         htlc_minimum_msat: 0,
3679                         htlc_maximum_msat: OptionalField::Present(200_000),
3680                         fee_base_msat: 0,
3681                         fee_proportional_millionths: 0,
3682                         excess_data: Vec::new()
3683                 });
3684
3685                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3686                 // Add 100 sats to the capacities of {12, 13}, because these channels
3687                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3688                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3689                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3690                         short_channel_id: 12,
3691                         timestamp: 2,
3692                         flags: 0,
3693                         cltv_expiry_delta: 0,
3694                         htlc_minimum_msat: 0,
3695                         htlc_maximum_msat: OptionalField::Present(200_000),
3696                         fee_base_msat: 0,
3697                         fee_proportional_millionths: 0,
3698                         excess_data: Vec::new()
3699                 });
3700                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3701                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3702                         short_channel_id: 13,
3703                         timestamp: 2,
3704                         flags: 0,
3705                         cltv_expiry_delta: 0,
3706                         htlc_minimum_msat: 0,
3707                         htlc_maximum_msat: OptionalField::Present(200_000),
3708                         fee_base_msat: 0,
3709                         fee_proportional_millionths: 0,
3710                         excess_data: Vec::new()
3711                 });
3712
3713                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3714                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3715                         short_channel_id: 6,
3716                         timestamp: 2,
3717                         flags: 0,
3718                         cltv_expiry_delta: 0,
3719                         htlc_minimum_msat: 0,
3720                         htlc_maximum_msat: OptionalField::Present(100_000),
3721                         fee_base_msat: 0,
3722                         fee_proportional_millionths: 0,
3723                         excess_data: Vec::new()
3724                 });
3725                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3726                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3727                         short_channel_id: 11,
3728                         timestamp: 2,
3729                         flags: 0,
3730                         cltv_expiry_delta: 0,
3731                         htlc_minimum_msat: 0,
3732                         htlc_maximum_msat: OptionalField::Present(100_000),
3733                         fee_base_msat: 0,
3734                         fee_proportional_millionths: 0,
3735                         excess_data: Vec::new()
3736                 });
3737
3738                 // Path via {node7, node2} is channels {12, 13, 5}.
3739                 // We already limited them to 200 sats (they are used twice for 100 sats).
3740                 // Nothing to do here.
3741
3742                 {
3743                         // Attempt to route more than available results in a failure.
3744                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3745                                         &our_id, &payment_params, &network_graph, None, 350_000, 42, Arc::clone(&logger), &scorer) {
3746                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3747                         } else { panic!(); }
3748                 }
3749
3750                 {
3751                         // Now, attempt to route 300 sats (exact amount we can route).
3752                         // Our algorithm should provide us with these 3 paths, 100 sats each.
3753                         let route = get_route(&our_id, &payment_params, &network_graph, None, 300_000, 42, Arc::clone(&logger), &scorer).unwrap();
3754                         assert_eq!(route.paths.len(), 3);
3755
3756                         let mut total_amount_paid_msat = 0;
3757                         for path in &route.paths {
3758                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3759                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3760                         }
3761                         assert_eq!(total_amount_paid_msat, 300_000);
3762                 }
3763
3764         }
3765
3766         #[test]
3767         fn mpp_cheaper_route_test() {
3768                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
3769                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3770                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
3771                 let payment_params = PaymentParameters::from_node_id(nodes[3]).with_features(InvoiceFeatures::known());
3772
3773                 // This test checks that if we have two cheaper paths and one more expensive path,
3774                 // so that liquidity-wise any 2 of 3 combination is sufficient,
3775                 // two cheaper paths will be taken.
3776                 // These paths have equal available liquidity.
3777
3778                 // We need a combination of 3 paths:
3779                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
3780                 // Note that these paths overlap (channels 5, 12, 13).
3781                 // Each path will have 100 sats capacity, those channels which
3782                 // are used twice will have 200 sats capacity.
3783
3784                 // Disable other potential paths.
3785                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3786                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3787                         short_channel_id: 2,
3788                         timestamp: 2,
3789                         flags: 2,
3790                         cltv_expiry_delta: 0,
3791                         htlc_minimum_msat: 0,
3792                         htlc_maximum_msat: OptionalField::Present(100_000),
3793                         fee_base_msat: 0,
3794                         fee_proportional_millionths: 0,
3795                         excess_data: Vec::new()
3796                 });
3797                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3798                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3799                         short_channel_id: 7,
3800                         timestamp: 2,
3801                         flags: 2,
3802                         cltv_expiry_delta: 0,
3803                         htlc_minimum_msat: 0,
3804                         htlc_maximum_msat: OptionalField::Present(100_000),
3805                         fee_base_msat: 0,
3806                         fee_proportional_millionths: 0,
3807                         excess_data: Vec::new()
3808                 });
3809
3810                 // Path via {node0, node2} is channels {1, 3, 5}.
3811                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3812                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3813                         short_channel_id: 1,
3814                         timestamp: 2,
3815                         flags: 0,
3816                         cltv_expiry_delta: 0,
3817                         htlc_minimum_msat: 0,
3818                         htlc_maximum_msat: OptionalField::Present(100_000),
3819                         fee_base_msat: 0,
3820                         fee_proportional_millionths: 0,
3821                         excess_data: Vec::new()
3822                 });
3823                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3824                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3825                         short_channel_id: 3,
3826                         timestamp: 2,
3827                         flags: 0,
3828                         cltv_expiry_delta: 0,
3829                         htlc_minimum_msat: 0,
3830                         htlc_maximum_msat: OptionalField::Present(100_000),
3831                         fee_base_msat: 0,
3832                         fee_proportional_millionths: 0,
3833                         excess_data: Vec::new()
3834                 });
3835
3836                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3837                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3838                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3839                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3840                         short_channel_id: 5,
3841                         timestamp: 2,
3842                         flags: 0,
3843                         cltv_expiry_delta: 0,
3844                         htlc_minimum_msat: 0,
3845                         htlc_maximum_msat: OptionalField::Present(200_000),
3846                         fee_base_msat: 0,
3847                         fee_proportional_millionths: 0,
3848                         excess_data: Vec::new()
3849                 });
3850
3851                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3852                 // Add 100 sats to the capacities of {12, 13}, because these channels
3853                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3854                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3855                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3856                         short_channel_id: 12,
3857                         timestamp: 2,
3858                         flags: 0,
3859                         cltv_expiry_delta: 0,
3860                         htlc_minimum_msat: 0,
3861                         htlc_maximum_msat: OptionalField::Present(200_000),
3862                         fee_base_msat: 0,
3863                         fee_proportional_millionths: 0,
3864                         excess_data: Vec::new()
3865                 });
3866                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3867                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3868                         short_channel_id: 13,
3869                         timestamp: 2,
3870                         flags: 0,
3871                         cltv_expiry_delta: 0,
3872                         htlc_minimum_msat: 0,
3873                         htlc_maximum_msat: OptionalField::Present(200_000),
3874                         fee_base_msat: 0,
3875                         fee_proportional_millionths: 0,
3876                         excess_data: Vec::new()
3877                 });
3878
3879                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3880                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3881                         short_channel_id: 6,
3882                         timestamp: 2,
3883                         flags: 0,
3884                         cltv_expiry_delta: 0,
3885                         htlc_minimum_msat: 0,
3886                         htlc_maximum_msat: OptionalField::Present(100_000),
3887                         fee_base_msat: 1_000,
3888                         fee_proportional_millionths: 0,
3889                         excess_data: Vec::new()
3890                 });
3891                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3892                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3893                         short_channel_id: 11,
3894                         timestamp: 2,
3895                         flags: 0,
3896                         cltv_expiry_delta: 0,
3897                         htlc_minimum_msat: 0,
3898                         htlc_maximum_msat: OptionalField::Present(100_000),
3899                         fee_base_msat: 0,
3900                         fee_proportional_millionths: 0,
3901                         excess_data: Vec::new()
3902                 });
3903
3904                 // Path via {node7, node2} is channels {12, 13, 5}.
3905                 // We already limited them to 200 sats (they are used twice for 100 sats).
3906                 // Nothing to do here.
3907
3908                 {
3909                         // Now, attempt to route 180 sats.
3910                         // Our algorithm should provide us with these 2 paths.
3911                         let route = get_route(&our_id, &payment_params, &network_graph, None, 180_000, 42, Arc::clone(&logger), &scorer).unwrap();
3912                         assert_eq!(route.paths.len(), 2);
3913
3914                         let mut total_value_transferred_msat = 0;
3915                         let mut total_paid_msat = 0;
3916                         for path in &route.paths {
3917                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3918                                 total_value_transferred_msat += path.last().unwrap().fee_msat;
3919                                 for hop in path {
3920                                         total_paid_msat += hop.fee_msat;
3921                                 }
3922                         }
3923                         // If we paid fee, this would be higher.
3924                         assert_eq!(total_value_transferred_msat, 180_000);
3925                         let total_fees_paid = total_paid_msat - total_value_transferred_msat;
3926                         assert_eq!(total_fees_paid, 0);
3927                 }
3928         }
3929
3930         #[test]
3931         fn fees_on_mpp_route_test() {
3932                 // This test makes sure that MPP algorithm properly takes into account
3933                 // fees charged on the channels, by making the fees impactful:
3934                 // if the fee is not properly accounted for, the behavior is different.
3935                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
3936                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3937                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
3938                 let payment_params = PaymentParameters::from_node_id(nodes[3]).with_features(InvoiceFeatures::known());
3939
3940                 // We need a route consisting of 2 paths:
3941                 // From our node to node3 via {node0, node2} and {node7, node2, node4}.
3942                 // We will route 200 sats, Each path will have 100 sats capacity.
3943
3944                 // This test is not particularly stable: e.g.,
3945                 // there's a way to route via {node0, node2, node4}.
3946                 // It works while pathfinding is deterministic, but can be broken otherwise.
3947                 // It's fine to ignore this concern for now.
3948
3949                 // Disable other potential paths.
3950                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3951                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3952                         short_channel_id: 2,
3953                         timestamp: 2,
3954                         flags: 2,
3955                         cltv_expiry_delta: 0,
3956                         htlc_minimum_msat: 0,
3957                         htlc_maximum_msat: OptionalField::Present(100_000),
3958                         fee_base_msat: 0,
3959                         fee_proportional_millionths: 0,
3960                         excess_data: Vec::new()
3961                 });
3962
3963                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3964                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3965                         short_channel_id: 7,
3966                         timestamp: 2,
3967                         flags: 2,
3968                         cltv_expiry_delta: 0,
3969                         htlc_minimum_msat: 0,
3970                         htlc_maximum_msat: OptionalField::Present(100_000),
3971                         fee_base_msat: 0,
3972                         fee_proportional_millionths: 0,
3973                         excess_data: Vec::new()
3974                 });
3975
3976                 // Path via {node0, node2} is channels {1, 3, 5}.
3977                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3978                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3979                         short_channel_id: 1,
3980                         timestamp: 2,
3981                         flags: 0,
3982                         cltv_expiry_delta: 0,
3983                         htlc_minimum_msat: 0,
3984                         htlc_maximum_msat: OptionalField::Present(100_000),
3985                         fee_base_msat: 0,
3986                         fee_proportional_millionths: 0,
3987                         excess_data: Vec::new()
3988                 });
3989                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3990                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3991                         short_channel_id: 3,
3992                         timestamp: 2,
3993                         flags: 0,
3994                         cltv_expiry_delta: 0,
3995                         htlc_minimum_msat: 0,
3996                         htlc_maximum_msat: OptionalField::Present(100_000),
3997                         fee_base_msat: 0,
3998                         fee_proportional_millionths: 0,
3999                         excess_data: Vec::new()
4000                 });
4001
4002                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
4003                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
4004                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4005                         short_channel_id: 5,
4006                         timestamp: 2,
4007                         flags: 0,
4008                         cltv_expiry_delta: 0,
4009                         htlc_minimum_msat: 0,
4010                         htlc_maximum_msat: OptionalField::Present(100_000),
4011                         fee_base_msat: 0,
4012                         fee_proportional_millionths: 0,
4013                         excess_data: Vec::new()
4014                 });
4015
4016                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
4017                 // All channels should be 100 sats capacity. But for the fee experiment,
4018                 // we'll add absolute fee of 150 sats paid for the use channel 6 (paid to node2 on channel 13).
4019                 // Since channel 12 allows to deliver only 250 sats to channel 13, channel 13 can transfer only
4020                 // 100 sats (and pay 150 sats in fees for the use of channel 6),
4021                 // so no matter how large are other channels,
4022                 // the whole path will be limited by 100 sats with just these 2 conditions:
4023                 // - channel 12 capacity is 250 sats
4024                 // - fee for channel 6 is 150 sats
4025                 // Let's test this by enforcing these 2 conditions and removing other limits.
4026                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4027                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4028                         short_channel_id: 12,
4029                         timestamp: 2,
4030                         flags: 0,
4031                         cltv_expiry_delta: 0,
4032                         htlc_minimum_msat: 0,
4033                         htlc_maximum_msat: OptionalField::Present(250_000),
4034                         fee_base_msat: 0,
4035                         fee_proportional_millionths: 0,
4036                         excess_data: Vec::new()
4037                 });
4038                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
4039                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4040                         short_channel_id: 13,
4041                         timestamp: 2,
4042                         flags: 0,
4043                         cltv_expiry_delta: 0,
4044                         htlc_minimum_msat: 0,
4045                         htlc_maximum_msat: OptionalField::Absent,
4046                         fee_base_msat: 0,
4047                         fee_proportional_millionths: 0,
4048                         excess_data: Vec::new()
4049                 });
4050
4051                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
4052                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4053                         short_channel_id: 6,
4054                         timestamp: 2,
4055                         flags: 0,
4056                         cltv_expiry_delta: 0,
4057                         htlc_minimum_msat: 0,
4058                         htlc_maximum_msat: OptionalField::Absent,
4059                         fee_base_msat: 150_000,
4060                         fee_proportional_millionths: 0,
4061                         excess_data: Vec::new()
4062                 });
4063                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
4064                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4065                         short_channel_id: 11,
4066                         timestamp: 2,
4067                         flags: 0,
4068                         cltv_expiry_delta: 0,
4069                         htlc_minimum_msat: 0,
4070                         htlc_maximum_msat: OptionalField::Absent,
4071                         fee_base_msat: 0,
4072                         fee_proportional_millionths: 0,
4073                         excess_data: Vec::new()
4074                 });
4075
4076                 {
4077                         // Attempt to route more than available results in a failure.
4078                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
4079                                         &our_id, &payment_params, &network_graph, None, 210_000, 42, Arc::clone(&logger), &scorer) {
4080                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
4081                         } else { panic!(); }
4082                 }
4083
4084                 {
4085                         // Now, attempt to route 200 sats (exact amount we can route).
4086                         let route = get_route(&our_id, &payment_params, &network_graph, None, 200_000, 42, Arc::clone(&logger), &scorer).unwrap();
4087                         assert_eq!(route.paths.len(), 2);
4088
4089                         let mut total_amount_paid_msat = 0;
4090                         for path in &route.paths {
4091                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
4092                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
4093                         }
4094                         assert_eq!(total_amount_paid_msat, 200_000);
4095                         assert_eq!(route.get_total_fees(), 150_000);
4096                 }
4097         }
4098
4099         #[test]
4100         fn mpp_with_last_hops() {
4101                 // Previously, if we tried to send an MPP payment to a destination which was only reachable
4102                 // via a single last-hop route hint, we'd fail to route if we first collected routes
4103                 // totaling close but not quite enough to fund the full payment.
4104                 //
4105                 // This was because we considered last-hop hints to have exactly the sought payment amount
4106                 // instead of the amount we were trying to collect, needlessly limiting our path searching
4107                 // at the very first hop.
4108                 //
4109                 // Specifically, this interacted with our "all paths must fund at least 5% of total target"
4110                 // criterion to cause us to refuse all routes at the last hop hint which would be considered
4111                 // to only have the remaining to-collect amount in available liquidity.
4112                 //
4113                 // This bug appeared in production in some specific channel configurations.
4114                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
4115                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
4116                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4117                 let payment_params = PaymentParameters::from_node_id(PublicKey::from_slice(&[02; 33]).unwrap()).with_features(InvoiceFeatures::known())
4118                         .with_route_hints(vec![RouteHint(vec![RouteHintHop {
4119                                 src_node_id: nodes[2],
4120                                 short_channel_id: 42,
4121                                 fees: RoutingFees { base_msat: 0, proportional_millionths: 0 },
4122                                 cltv_expiry_delta: 42,
4123                                 htlc_minimum_msat: None,
4124                                 htlc_maximum_msat: None,
4125                         }])]);
4126
4127                 // Keep only two paths from us to nodes[2], both with a 99sat HTLC maximum, with one with
4128                 // no fee and one with a 1msat fee. Previously, trying to route 100 sats to nodes[2] here
4129                 // would first use the no-fee route and then fail to find a path along the second route as
4130                 // we think we can only send up to 1 additional sat over the last-hop but refuse to as its
4131                 // under 5% of our payment amount.
4132                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4133                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4134                         short_channel_id: 1,
4135                         timestamp: 2,
4136                         flags: 0,
4137                         cltv_expiry_delta: (5 << 4) | 5,
4138                         htlc_minimum_msat: 0,
4139                         htlc_maximum_msat: OptionalField::Present(99_000),
4140                         fee_base_msat: u32::max_value(),
4141                         fee_proportional_millionths: u32::max_value(),
4142                         excess_data: Vec::new()
4143                 });
4144                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4145                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4146                         short_channel_id: 2,
4147                         timestamp: 2,
4148                         flags: 0,
4149                         cltv_expiry_delta: (5 << 4) | 3,
4150                         htlc_minimum_msat: 0,
4151                         htlc_maximum_msat: OptionalField::Present(99_000),
4152                         fee_base_msat: u32::max_value(),
4153                         fee_proportional_millionths: u32::max_value(),
4154                         excess_data: Vec::new()
4155                 });
4156                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
4157                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4158                         short_channel_id: 4,
4159                         timestamp: 2,
4160                         flags: 0,
4161                         cltv_expiry_delta: (4 << 4) | 1,
4162                         htlc_minimum_msat: 0,
4163                         htlc_maximum_msat: OptionalField::Absent,
4164                         fee_base_msat: 1,
4165                         fee_proportional_millionths: 0,
4166                         excess_data: Vec::new()
4167                 });
4168                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
4169                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4170                         short_channel_id: 13,
4171                         timestamp: 2,
4172                         flags: 0|2, // Channel disabled
4173                         cltv_expiry_delta: (13 << 4) | 1,
4174                         htlc_minimum_msat: 0,
4175                         htlc_maximum_msat: OptionalField::Absent,
4176                         fee_base_msat: 0,
4177                         fee_proportional_millionths: 2000000,
4178                         excess_data: Vec::new()
4179                 });
4180
4181                 // Get a route for 100 sats and check that we found the MPP route no problem and didn't
4182                 // overpay at all.
4183                 let route = get_route(&our_id, &payment_params, &network_graph, None, 100_000, 42, Arc::clone(&logger), &scorer).unwrap();
4184                 assert_eq!(route.paths.len(), 2);
4185                 // Paths are somewhat randomly ordered, but:
4186                 // * the first is channel 2 (1 msat fee) -> channel 4 -> channel 42
4187                 // * the second is channel 1 (0 fee, but 99 sat maximum) -> channel 3 -> channel 42
4188                 assert_eq!(route.paths[0][0].short_channel_id, 2);
4189                 assert_eq!(route.paths[0][0].fee_msat, 1);
4190                 assert_eq!(route.paths[0][2].fee_msat, 1_000);
4191                 assert_eq!(route.paths[1][0].short_channel_id, 1);
4192                 assert_eq!(route.paths[1][0].fee_msat, 0);
4193                 assert_eq!(route.paths[1][2].fee_msat, 99_000);
4194                 assert_eq!(route.get_total_fees(), 1);
4195                 assert_eq!(route.get_total_amount(), 100_000);
4196         }
4197
4198         #[test]
4199         fn drop_lowest_channel_mpp_route_test() {
4200                 // This test checks that low-capacity channel is dropped when after
4201                 // path finding we realize that we found more capacity than we need.
4202                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
4203                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
4204                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4205                 let payment_params = PaymentParameters::from_node_id(nodes[2]).with_features(InvoiceFeatures::known());
4206
4207                 // We need a route consisting of 3 paths:
4208                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
4209
4210                 // The first and the second paths should be sufficient, but the third should be
4211                 // cheaper, so that we select it but drop later.
4212
4213                 // First, we set limits on these (previously unlimited) channels.
4214                 // Their aggregate capacity will be 50 + 60 + 20 = 130 sats.
4215
4216                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50);
4217                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4218                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4219                         short_channel_id: 1,
4220                         timestamp: 2,
4221                         flags: 0,
4222                         cltv_expiry_delta: 0,
4223                         htlc_minimum_msat: 0,
4224                         htlc_maximum_msat: OptionalField::Present(100_000),
4225                         fee_base_msat: 0,
4226                         fee_proportional_millionths: 0,
4227                         excess_data: Vec::new()
4228                 });
4229                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
4230                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4231                         short_channel_id: 3,
4232                         timestamp: 2,
4233                         flags: 0,
4234                         cltv_expiry_delta: 0,
4235                         htlc_minimum_msat: 0,
4236                         htlc_maximum_msat: OptionalField::Present(50_000),
4237                         fee_base_msat: 100,
4238                         fee_proportional_millionths: 0,
4239                         excess_data: Vec::new()
4240                 });
4241
4242                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats (total limit 60);
4243                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4244                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4245                         short_channel_id: 12,
4246                         timestamp: 2,
4247                         flags: 0,
4248                         cltv_expiry_delta: 0,
4249                         htlc_minimum_msat: 0,
4250                         htlc_maximum_msat: OptionalField::Present(60_000),
4251                         fee_base_msat: 100,
4252                         fee_proportional_millionths: 0,
4253                         excess_data: Vec::new()
4254                 });
4255                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
4256                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4257                         short_channel_id: 13,
4258                         timestamp: 2,
4259                         flags: 0,
4260                         cltv_expiry_delta: 0,
4261                         htlc_minimum_msat: 0,
4262                         htlc_maximum_msat: OptionalField::Present(60_000),
4263                         fee_base_msat: 0,
4264                         fee_proportional_millionths: 0,
4265                         excess_data: Vec::new()
4266                 });
4267
4268                 // Path via node1 is channels {2, 4}. Limit them to 20 and 20 sats (total capacity 20 sats).
4269                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4270                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4271                         short_channel_id: 2,
4272                         timestamp: 2,
4273                         flags: 0,
4274                         cltv_expiry_delta: 0,
4275                         htlc_minimum_msat: 0,
4276                         htlc_maximum_msat: OptionalField::Present(20_000),
4277                         fee_base_msat: 0,
4278                         fee_proportional_millionths: 0,
4279                         excess_data: Vec::new()
4280                 });
4281                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
4282                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4283                         short_channel_id: 4,
4284                         timestamp: 2,
4285                         flags: 0,
4286                         cltv_expiry_delta: 0,
4287                         htlc_minimum_msat: 0,
4288                         htlc_maximum_msat: OptionalField::Present(20_000),
4289                         fee_base_msat: 0,
4290                         fee_proportional_millionths: 0,
4291                         excess_data: Vec::new()
4292                 });
4293
4294                 {
4295                         // Attempt to route more than available results in a failure.
4296                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
4297                                         &our_id, &payment_params, &network_graph, None, 150_000, 42, Arc::clone(&logger), &scorer) {
4298                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
4299                         } else { panic!(); }
4300                 }
4301
4302                 {
4303                         // Now, attempt to route 125 sats (just a bit below the capacity of 3 channels).
4304                         // Our algorithm should provide us with these 3 paths.
4305                         let route = get_route(&our_id, &payment_params, &network_graph, None, 125_000, 42, Arc::clone(&logger), &scorer).unwrap();
4306                         assert_eq!(route.paths.len(), 3);
4307                         let mut total_amount_paid_msat = 0;
4308                         for path in &route.paths {
4309                                 assert_eq!(path.len(), 2);
4310                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
4311                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
4312                         }
4313                         assert_eq!(total_amount_paid_msat, 125_000);
4314                 }
4315
4316                 {
4317                         // Attempt to route without the last small cheap channel
4318                         let route = get_route(&our_id, &payment_params, &network_graph, None, 90_000, 42, Arc::clone(&logger), &scorer).unwrap();
4319                         assert_eq!(route.paths.len(), 2);
4320                         let mut total_amount_paid_msat = 0;
4321                         for path in &route.paths {
4322                                 assert_eq!(path.len(), 2);
4323                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
4324                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
4325                         }
4326                         assert_eq!(total_amount_paid_msat, 90_000);
4327                 }
4328         }
4329
4330         #[test]
4331         fn min_criteria_consistency() {
4332                 // Test that we don't use an inconsistent metric between updating and walking nodes during
4333                 // our Dijkstra's pass. In the initial version of MPP, the "best source" for a given node
4334                 // was updated with a different criterion from the heap sorting, resulting in loops in
4335                 // calculated paths. We test for that specific case here.
4336
4337                 // We construct a network that looks like this:
4338                 //
4339                 //            node2 -1(3)2- node3
4340                 //              2          2
4341                 //               (2)     (4)
4342                 //                  1   1
4343                 //    node1 -1(5)2- node4 -1(1)2- node6
4344                 //    2
4345                 //   (6)
4346                 //        1
4347                 // our_node
4348                 //
4349                 // We create a loop on the side of our real path - our destination is node 6, with a
4350                 // previous hop of node 4. From 4, the cheapest previous path is channel 2 from node 2,
4351                 // followed by node 3 over channel 3. Thereafter, the cheapest next-hop is back to node 4
4352                 // (this time over channel 4). Channel 4 has 0 htlc_minimum_msat whereas channel 1 (the
4353                 // other channel with a previous-hop of node 4) has a high (but irrelevant to the overall
4354                 // payment) htlc_minimum_msat. In the original algorithm, this resulted in node4's
4355                 // "previous hop" being set to node 3, creating a loop in the path.
4356                 let secp_ctx = Secp256k1::new();
4357                 let logger = Arc::new(test_utils::TestLogger::new());
4358                 let network_graph = Arc::new(NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash()));
4359                 let net_graph_msg_handler = NetGraphMsgHandler::new(Arc::clone(&network_graph), None, Arc::clone(&logger));
4360                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
4361                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4362                 let payment_params = PaymentParameters::from_node_id(nodes[6]);
4363
4364                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
4365                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4366                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4367                         short_channel_id: 6,
4368                         timestamp: 1,
4369                         flags: 0,
4370                         cltv_expiry_delta: (6 << 4) | 0,
4371                         htlc_minimum_msat: 0,
4372                         htlc_maximum_msat: OptionalField::Absent,
4373                         fee_base_msat: 0,
4374                         fee_proportional_millionths: 0,
4375                         excess_data: Vec::new()
4376                 });
4377                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
4378
4379                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
4380                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
4381                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4382                         short_channel_id: 5,
4383                         timestamp: 1,
4384                         flags: 0,
4385                         cltv_expiry_delta: (5 << 4) | 0,
4386                         htlc_minimum_msat: 0,
4387                         htlc_maximum_msat: OptionalField::Absent,
4388                         fee_base_msat: 100,
4389                         fee_proportional_millionths: 0,
4390                         excess_data: Vec::new()
4391                 });
4392                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
4393
4394                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
4395                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
4396                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4397                         short_channel_id: 4,
4398                         timestamp: 1,
4399                         flags: 0,
4400                         cltv_expiry_delta: (4 << 4) | 0,
4401                         htlc_minimum_msat: 0,
4402                         htlc_maximum_msat: OptionalField::Absent,
4403                         fee_base_msat: 0,
4404                         fee_proportional_millionths: 0,
4405                         excess_data: Vec::new()
4406                 });
4407                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
4408
4409                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
4410                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
4411                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4412                         short_channel_id: 3,
4413                         timestamp: 1,
4414                         flags: 0,
4415                         cltv_expiry_delta: (3 << 4) | 0,
4416                         htlc_minimum_msat: 0,
4417                         htlc_maximum_msat: OptionalField::Absent,
4418                         fee_base_msat: 0,
4419                         fee_proportional_millionths: 0,
4420                         excess_data: Vec::new()
4421                 });
4422                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
4423
4424                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
4425                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
4426                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4427                         short_channel_id: 2,
4428                         timestamp: 1,
4429                         flags: 0,
4430                         cltv_expiry_delta: (2 << 4) | 0,
4431                         htlc_minimum_msat: 0,
4432                         htlc_maximum_msat: OptionalField::Absent,
4433                         fee_base_msat: 0,
4434                         fee_proportional_millionths: 0,
4435                         excess_data: Vec::new()
4436                 });
4437
4438                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[6], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
4439                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
4440                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4441                         short_channel_id: 1,
4442                         timestamp: 1,
4443                         flags: 0,
4444                         cltv_expiry_delta: (1 << 4) | 0,
4445                         htlc_minimum_msat: 100,
4446                         htlc_maximum_msat: OptionalField::Absent,
4447                         fee_base_msat: 0,
4448                         fee_proportional_millionths: 0,
4449                         excess_data: Vec::new()
4450                 });
4451                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[6], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
4452
4453                 {
4454                         // Now ensure the route flows simply over nodes 1 and 4 to 6.
4455                         let route = get_route(&our_id, &payment_params, &network_graph, None, 10_000, 42, Arc::clone(&logger), &scorer).unwrap();
4456                         assert_eq!(route.paths.len(), 1);
4457                         assert_eq!(route.paths[0].len(), 3);
4458
4459                         assert_eq!(route.paths[0][0].pubkey, nodes[1]);
4460                         assert_eq!(route.paths[0][0].short_channel_id, 6);
4461                         assert_eq!(route.paths[0][0].fee_msat, 100);
4462                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (5 << 4) | 0);
4463                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(1));
4464                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(6));
4465
4466                         assert_eq!(route.paths[0][1].pubkey, nodes[4]);
4467                         assert_eq!(route.paths[0][1].short_channel_id, 5);
4468                         assert_eq!(route.paths[0][1].fee_msat, 0);
4469                         assert_eq!(route.paths[0][1].cltv_expiry_delta, (1 << 4) | 0);
4470                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(4));
4471                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(5));
4472
4473                         assert_eq!(route.paths[0][2].pubkey, nodes[6]);
4474                         assert_eq!(route.paths[0][2].short_channel_id, 1);
4475                         assert_eq!(route.paths[0][2].fee_msat, 10_000);
4476                         assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
4477                         assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
4478                         assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(1));
4479                 }
4480         }
4481
4482
4483         #[test]
4484         fn exact_fee_liquidity_limit() {
4485                 // Test that if, while walking the graph, we find a hop that has exactly enough liquidity
4486                 // for us, including later hop fees, we take it. In the first version of our MPP algorithm
4487                 // we calculated fees on a higher value, resulting in us ignoring such paths.
4488                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
4489                 let (our_privkey, our_id, _, nodes) = get_nodes(&secp_ctx);
4490                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4491                 let payment_params = PaymentParameters::from_node_id(nodes[2]);
4492
4493                 // We modify the graph to set the htlc_maximum of channel 2 to below the value we wish to
4494                 // send.
4495                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4496                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4497                         short_channel_id: 2,
4498                         timestamp: 2,
4499                         flags: 0,
4500                         cltv_expiry_delta: 0,
4501                         htlc_minimum_msat: 0,
4502                         htlc_maximum_msat: OptionalField::Present(85_000),
4503                         fee_base_msat: 0,
4504                         fee_proportional_millionths: 0,
4505                         excess_data: Vec::new()
4506                 });
4507
4508                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4509                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4510                         short_channel_id: 12,
4511                         timestamp: 2,
4512                         flags: 0,
4513                         cltv_expiry_delta: (4 << 4) | 1,
4514                         htlc_minimum_msat: 0,
4515                         htlc_maximum_msat: OptionalField::Present(270_000),
4516                         fee_base_msat: 0,
4517                         fee_proportional_millionths: 1000000,
4518                         excess_data: Vec::new()
4519                 });
4520
4521                 {
4522                         // Now, attempt to route 90 sats, which is exactly 90 sats at the last hop, plus the
4523                         // 200% fee charged channel 13 in the 1-to-2 direction.
4524                         let route = get_route(&our_id, &payment_params, &network_graph, None, 90_000, 42, Arc::clone(&logger), &scorer).unwrap();
4525                         assert_eq!(route.paths.len(), 1);
4526                         assert_eq!(route.paths[0].len(), 2);
4527
4528                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
4529                         assert_eq!(route.paths[0][0].short_channel_id, 12);
4530                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
4531                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 4) | 1);
4532                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
4533                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
4534
4535                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
4536                         assert_eq!(route.paths[0][1].short_channel_id, 13);
4537                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
4538                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
4539                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
4540                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
4541                 }
4542         }
4543
4544         #[test]
4545         fn htlc_max_reduction_below_min() {
4546                 // Test that if, while walking the graph, we reduce the value being sent to meet an
4547                 // htlc_maximum_msat, we don't end up undershooting a later htlc_minimum_msat. In the
4548                 // initial version of MPP we'd accept such routes but reject them while recalculating fees,
4549                 // resulting in us thinking there is no possible path, even if other paths exist.
4550                 let (secp_ctx, network_graph, net_graph_msg_handler, _, logger) = build_graph();
4551                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
4552                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4553                 let payment_params = PaymentParameters::from_node_id(nodes[2]).with_features(InvoiceFeatures::known());
4554
4555                 // We modify the graph to set the htlc_minimum of channel 2 and 4 as needed - channel 2
4556                 // gets an htlc_maximum_msat of 80_000 and channel 4 an htlc_minimum_msat of 90_000. We
4557                 // then try to send 90_000.
4558                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4559                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4560                         short_channel_id: 2,
4561                         timestamp: 2,
4562                         flags: 0,
4563                         cltv_expiry_delta: 0,
4564                         htlc_minimum_msat: 0,
4565                         htlc_maximum_msat: OptionalField::Present(80_000),
4566                         fee_base_msat: 0,
4567                         fee_proportional_millionths: 0,
4568                         excess_data: Vec::new()
4569                 });
4570                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
4571                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4572                         short_channel_id: 4,
4573                         timestamp: 2,
4574                         flags: 0,
4575                         cltv_expiry_delta: (4 << 4) | 1,
4576                         htlc_minimum_msat: 90_000,
4577                         htlc_maximum_msat: OptionalField::Absent,
4578                         fee_base_msat: 0,
4579                         fee_proportional_millionths: 0,
4580                         excess_data: Vec::new()
4581                 });
4582
4583                 {
4584                         // Now, attempt to route 90 sats, hitting the htlc_minimum on channel 4, but
4585                         // overshooting the htlc_maximum on channel 2. Thus, we should pick the (absurdly
4586                         // expensive) channels 12-13 path.
4587                         let route = get_route(&our_id, &payment_params, &network_graph, None, 90_000, 42, Arc::clone(&logger), &scorer).unwrap();
4588                         assert_eq!(route.paths.len(), 1);
4589                         assert_eq!(route.paths[0].len(), 2);
4590
4591                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
4592                         assert_eq!(route.paths[0][0].short_channel_id, 12);
4593                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
4594                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 4) | 1);
4595                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
4596                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
4597
4598                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
4599                         assert_eq!(route.paths[0][1].short_channel_id, 13);
4600                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
4601                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
4602                         assert_eq!(route.paths[0][1].node_features.le_flags(), InvoiceFeatures::known().le_flags());
4603                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
4604                 }
4605         }
4606
4607         #[test]
4608         fn multiple_direct_first_hops() {
4609                 // Previously we'd only ever considered one first hop path per counterparty.
4610                 // However, as we don't restrict users to one channel per peer, we really need to support
4611                 // looking at all first hop paths.
4612                 // Here we test that we do not ignore all-but-the-last first hop paths per counterparty (as
4613                 // we used to do by overwriting the `first_hop_targets` hashmap entry) and that we can MPP
4614                 // route over multiple channels with the same first hop.
4615                 let secp_ctx = Secp256k1::new();
4616                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
4617                 let logger = Arc::new(test_utils::TestLogger::new());
4618                 let network_graph = NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash());
4619                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4620                 let payment_params = PaymentParameters::from_node_id(nodes[0]).with_features(InvoiceFeatures::known());
4621
4622                 {
4623                         let route = get_route(&our_id, &payment_params, &network_graph, Some(&[
4624                                 &get_channel_details(Some(3), nodes[0], InitFeatures::known(), 200_000),
4625                                 &get_channel_details(Some(2), nodes[0], InitFeatures::known(), 10_000),
4626                         ]), 100_000, 42, Arc::clone(&logger), &scorer).unwrap();
4627                         assert_eq!(route.paths.len(), 1);
4628                         assert_eq!(route.paths[0].len(), 1);
4629
4630                         assert_eq!(route.paths[0][0].pubkey, nodes[0]);
4631                         assert_eq!(route.paths[0][0].short_channel_id, 3);
4632                         assert_eq!(route.paths[0][0].fee_msat, 100_000);
4633                 }
4634                 {
4635                         let route = get_route(&our_id, &payment_params, &network_graph, Some(&[
4636                                 &get_channel_details(Some(3), nodes[0], InitFeatures::known(), 50_000),
4637                                 &get_channel_details(Some(2), nodes[0], InitFeatures::known(), 50_000),
4638                         ]), 100_000, 42, Arc::clone(&logger), &scorer).unwrap();
4639                         assert_eq!(route.paths.len(), 2);
4640                         assert_eq!(route.paths[0].len(), 1);
4641                         assert_eq!(route.paths[1].len(), 1);
4642
4643                         assert_eq!(route.paths[0][0].pubkey, nodes[0]);
4644                         assert_eq!(route.paths[0][0].short_channel_id, 3);
4645                         assert_eq!(route.paths[0][0].fee_msat, 50_000);
4646
4647                         assert_eq!(route.paths[1][0].pubkey, nodes[0]);
4648                         assert_eq!(route.paths[1][0].short_channel_id, 2);
4649                         assert_eq!(route.paths[1][0].fee_msat, 50_000);
4650                 }
4651         }
4652
4653         #[test]
4654         fn prefers_shorter_route_with_higher_fees() {
4655                 let (secp_ctx, network_graph, _, _, logger) = build_graph();
4656                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
4657                 let payment_params = PaymentParameters::from_node_id(nodes[6]).with_route_hints(last_hops(&nodes));
4658
4659                 // Without penalizing each hop 100 msats, a longer path with lower fees is chosen.
4660                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4661                 let route = get_route(
4662                         &our_id, &payment_params, &network_graph, None, 100, 42,
4663                         Arc::clone(&logger), &scorer
4664                 ).unwrap();
4665                 let path = route.paths[0].iter().map(|hop| hop.short_channel_id).collect::<Vec<_>>();
4666
4667                 assert_eq!(route.get_total_fees(), 100);
4668                 assert_eq!(route.get_total_amount(), 100);
4669                 assert_eq!(path, vec![2, 4, 6, 11, 8]);
4670
4671                 // Applying a 100 msat penalty to each hop results in taking channels 7 and 10 to nodes[6]
4672                 // from nodes[2] rather than channel 6, 11, and 8, even though the longer path is cheaper.
4673                 let scorer = test_utils::TestScorer::with_fixed_penalty(100);
4674                 let route = get_route(
4675                         &our_id, &payment_params, &network_graph, None, 100, 42,
4676                         Arc::clone(&logger), &scorer
4677                 ).unwrap();
4678                 let path = route.paths[0].iter().map(|hop| hop.short_channel_id).collect::<Vec<_>>();
4679
4680                 assert_eq!(route.get_total_fees(), 300);
4681                 assert_eq!(route.get_total_amount(), 100);
4682                 assert_eq!(path, vec![2, 4, 7, 10]);
4683         }
4684
4685         struct BadChannelScorer {
4686                 short_channel_id: u64,
4687         }
4688
4689         #[cfg(c_bindings)]
4690         impl Writeable for BadChannelScorer {
4691                 fn write<W: Writer>(&self, _w: &mut W) -> Result<(), ::io::Error> { unimplemented!() }
4692         }
4693         impl Score for BadChannelScorer {
4694                 fn channel_penalty_msat(&self, short_channel_id: u64, _send_amt: u64, _chan_amt: Option<u64>, _source: &NodeId, _target: &NodeId) -> u64 {
4695                         if short_channel_id == self.short_channel_id { u64::max_value() } else { 0 }
4696                 }
4697
4698                 fn payment_path_failed(&mut self, _path: &[&RouteHop], _short_channel_id: u64) {}
4699                 fn payment_path_successful(&mut self, _path: &[&RouteHop]) {}
4700         }
4701
4702         struct BadNodeScorer {
4703                 node_id: NodeId,
4704         }
4705
4706         #[cfg(c_bindings)]
4707         impl Writeable for BadNodeScorer {
4708                 fn write<W: Writer>(&self, _w: &mut W) -> Result<(), ::io::Error> { unimplemented!() }
4709         }
4710
4711         impl Score for BadNodeScorer {
4712                 fn channel_penalty_msat(&self, _short_channel_id: u64, _send_amt: u64, _chan_amt: Option<u64>, _source: &NodeId, target: &NodeId) -> u64 {
4713                         if *target == self.node_id { u64::max_value() } else { 0 }
4714                 }
4715
4716                 fn payment_path_failed(&mut self, _path: &[&RouteHop], _short_channel_id: u64) {}
4717                 fn payment_path_successful(&mut self, _path: &[&RouteHop]) {}
4718         }
4719
4720         #[test]
4721         fn avoids_routing_through_bad_channels_and_nodes() {
4722                 let (secp_ctx, network_graph, _, _, logger) = build_graph();
4723                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
4724                 let payment_params = PaymentParameters::from_node_id(nodes[6]).with_route_hints(last_hops(&nodes));
4725
4726                 // A path to nodes[6] exists when no penalties are applied to any channel.
4727                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4728                 let route = get_route(
4729                         &our_id, &payment_params, &network_graph, None, 100, 42,
4730                         Arc::clone(&logger), &scorer
4731                 ).unwrap();
4732                 let path = route.paths[0].iter().map(|hop| hop.short_channel_id).collect::<Vec<_>>();
4733
4734                 assert_eq!(route.get_total_fees(), 100);
4735                 assert_eq!(route.get_total_amount(), 100);
4736                 assert_eq!(path, vec![2, 4, 6, 11, 8]);
4737
4738                 // A different path to nodes[6] exists if channel 6 cannot be routed over.
4739                 let scorer = BadChannelScorer { short_channel_id: 6 };
4740                 let route = get_route(
4741                         &our_id, &payment_params, &network_graph, None, 100, 42,
4742                         Arc::clone(&logger), &scorer
4743                 ).unwrap();
4744                 let path = route.paths[0].iter().map(|hop| hop.short_channel_id).collect::<Vec<_>>();
4745
4746                 assert_eq!(route.get_total_fees(), 300);
4747                 assert_eq!(route.get_total_amount(), 100);
4748                 assert_eq!(path, vec![2, 4, 7, 10]);
4749
4750                 // A path to nodes[6] does not exist if nodes[2] cannot be routed through.
4751                 let scorer = BadNodeScorer { node_id: NodeId::from_pubkey(&nodes[2]) };
4752                 match get_route(
4753                         &our_id, &payment_params, &network_graph, None, 100, 42,
4754                         Arc::clone(&logger), &scorer
4755                 ) {
4756                         Err(LightningError { err, .. } ) => {
4757                                 assert_eq!(err, "Failed to find a path to the given destination");
4758                         },
4759                         Ok(_) => panic!("Expected error"),
4760                 }
4761         }
4762
4763         #[test]
4764         fn total_fees_single_path() {
4765                 let route = Route {
4766                         paths: vec![vec![
4767                                 RouteHop {
4768                                         pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
4769                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4770                                         short_channel_id: 0, fee_msat: 100, cltv_expiry_delta: 0
4771                                 },
4772                                 RouteHop {
4773                                         pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
4774                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4775                                         short_channel_id: 0, fee_msat: 150, cltv_expiry_delta: 0
4776                                 },
4777                                 RouteHop {
4778                                         pubkey: PublicKey::from_slice(&hex::decode("027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007").unwrap()[..]).unwrap(),
4779                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4780                                         short_channel_id: 0, fee_msat: 225, cltv_expiry_delta: 0
4781                                 },
4782                         ]],
4783                         payment_params: None,
4784                 };
4785
4786                 assert_eq!(route.get_total_fees(), 250);
4787                 assert_eq!(route.get_total_amount(), 225);
4788         }
4789
4790         #[test]
4791         fn total_fees_multi_path() {
4792                 let route = Route {
4793                         paths: vec![vec![
4794                                 RouteHop {
4795                                         pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
4796                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4797                                         short_channel_id: 0, fee_msat: 100, cltv_expiry_delta: 0
4798                                 },
4799                                 RouteHop {
4800                                         pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
4801                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4802                                         short_channel_id: 0, fee_msat: 150, cltv_expiry_delta: 0
4803                                 },
4804                         ],vec![
4805                                 RouteHop {
4806                                         pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
4807                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4808                                         short_channel_id: 0, fee_msat: 100, cltv_expiry_delta: 0
4809                                 },
4810                                 RouteHop {
4811                                         pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
4812                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4813                                         short_channel_id: 0, fee_msat: 150, cltv_expiry_delta: 0
4814                                 },
4815                         ]],
4816                         payment_params: None,
4817                 };
4818
4819                 assert_eq!(route.get_total_fees(), 200);
4820                 assert_eq!(route.get_total_amount(), 300);
4821         }
4822
4823         #[test]
4824         fn total_empty_route_no_panic() {
4825                 // In an earlier version of `Route::get_total_fees` and `Route::get_total_amount`, they
4826                 // would both panic if the route was completely empty. We test to ensure they return 0
4827                 // here, even though its somewhat nonsensical as a route.
4828                 let route = Route { paths: Vec::new(), payment_params: None };
4829
4830                 assert_eq!(route.get_total_fees(), 0);
4831                 assert_eq!(route.get_total_amount(), 0);
4832         }
4833
4834         #[test]
4835         fn limits_total_cltv_delta() {
4836                 let (secp_ctx, network_graph, _, _, logger) = build_graph();
4837                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
4838
4839                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4840
4841                 // Make sure that generally there is at least one route available
4842                 let feasible_max_total_cltv_delta = 1008;
4843                 let feasible_payment_params = PaymentParameters::from_node_id(nodes[6]).with_route_hints(last_hops(&nodes))
4844                         .with_max_total_cltv_expiry_delta(feasible_max_total_cltv_delta);
4845                 let route = get_route(&our_id, &feasible_payment_params, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
4846                 let path = route.paths[0].iter().map(|hop| hop.short_channel_id).collect::<Vec<_>>();
4847                 assert_ne!(path.len(), 0);
4848
4849                 // But not if we exclude all paths on the basis of their accumulated CLTV delta
4850                 let fail_max_total_cltv_delta = 23;
4851                 let fail_payment_params = PaymentParameters::from_node_id(nodes[6]).with_route_hints(last_hops(&nodes))
4852                         .with_max_total_cltv_expiry_delta(fail_max_total_cltv_delta);
4853                 match get_route(&our_id, &fail_payment_params, &network_graph, None, 100, 42, Arc::clone(&logger), &scorer)
4854                 {
4855                         Err(LightningError { err, .. } ) => {
4856                                 assert_eq!(err, "Failed to find a path to the given destination");
4857                         },
4858                         Ok(_) => panic!("Expected error"),
4859                 }
4860         }
4861
4862         #[cfg(not(feature = "no-std"))]
4863         pub(super) fn random_init_seed() -> u64 {
4864                 // Because the default HashMap in std pulls OS randomness, we can use it as a (bad) RNG.
4865                 use core::hash::{BuildHasher, Hasher};
4866                 let seed = std::collections::hash_map::RandomState::new().build_hasher().finish();
4867                 println!("Using seed of {}", seed);
4868                 seed
4869         }
4870         #[cfg(not(feature = "no-std"))]
4871         use util::ser::Readable;
4872
4873         #[test]
4874         #[cfg(not(feature = "no-std"))]
4875         fn generate_routes() {
4876                 let mut d = match super::test_utils::get_route_file() {
4877                         Ok(f) => f,
4878                         Err(e) => {
4879                                 eprintln!("{}", e);
4880                                 return;
4881                         },
4882                 };
4883                 let graph = NetworkGraph::read(&mut d).unwrap();
4884                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4885
4886                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
4887                 let mut seed = random_init_seed() as usize;
4888                 let nodes = graph.read_only().nodes().clone();
4889                 'load_endpoints: for _ in 0..10 {
4890                         loop {
4891                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4892                                 let src = &PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4893                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4894                                 let dst = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4895                                 let payment_params = PaymentParameters::from_node_id(dst);
4896                                 let amt = seed as u64 % 200_000_000;
4897                                 if get_route(src, &payment_params, &graph, None, amt, 42, &test_utils::TestLogger::new(), &scorer).is_ok() {
4898                                         continue 'load_endpoints;
4899                                 }
4900                         }
4901                 }
4902         }
4903
4904         #[test]
4905         #[cfg(not(feature = "no-std"))]
4906         fn generate_routes_mpp() {
4907                 let mut d = match super::test_utils::get_route_file() {
4908                         Ok(f) => f,
4909                         Err(e) => {
4910                                 eprintln!("{}", e);
4911                                 return;
4912                         },
4913                 };
4914                 let graph = NetworkGraph::read(&mut d).unwrap();
4915                 let scorer = test_utils::TestScorer::with_fixed_penalty(0);
4916
4917                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
4918                 let mut seed = random_init_seed() as usize;
4919                 let nodes = graph.read_only().nodes().clone();
4920                 'load_endpoints: for _ in 0..10 {
4921                         loop {
4922                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4923                                 let src = &PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4924                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4925                                 let dst = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4926                                 let payment_params = PaymentParameters::from_node_id(dst).with_features(InvoiceFeatures::known());
4927                                 let amt = seed as u64 % 200_000_000;
4928                                 if get_route(src, &payment_params, &graph, None, amt, 42, &test_utils::TestLogger::new(), &scorer).is_ok() {
4929                                         continue 'load_endpoints;
4930                                 }
4931                         }
4932                 }
4933         }
4934 }
4935
4936 #[cfg(all(test, not(feature = "no-std")))]
4937 pub(crate) mod test_utils {
4938         use std::fs::File;
4939         /// Tries to open a network graph file, or panics with a URL to fetch it.
4940         pub(crate) fn get_route_file() -> Result<std::fs::File, &'static str> {
4941                 let res = File::open("net_graph-2021-05-31.bin") // By default we're run in RL/lightning
4942                         .or_else(|_| File::open("lightning/net_graph-2021-05-31.bin")) // We may be run manually in RL/
4943                         .or_else(|_| { // Fall back to guessing based on the binary location
4944                                 // path is likely something like .../rust-lightning/target/debug/deps/lightning-...
4945                                 let mut path = std::env::current_exe().unwrap();
4946                                 path.pop(); // lightning-...
4947                                 path.pop(); // deps
4948                                 path.pop(); // debug
4949                                 path.pop(); // target
4950                                 path.push("lightning");
4951                                 path.push("net_graph-2021-05-31.bin");
4952                                 eprintln!("{}", path.to_str().unwrap());
4953                                 File::open(path)
4954                         })
4955                 .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");
4956                 #[cfg(require_route_graph_test)]
4957                 return Ok(res.unwrap());
4958                 #[cfg(not(require_route_graph_test))]
4959                 return res;
4960         }
4961 }
4962
4963 #[cfg(all(test, feature = "unstable", not(feature = "no-std")))]
4964 mod benches {
4965         use super::*;
4966         use bitcoin::hashes::Hash;
4967         use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
4968         use chain::transaction::OutPoint;
4969         use ln::channelmanager::{ChannelCounterparty, ChannelDetails};
4970         use ln::features::{InitFeatures, InvoiceFeatures};
4971         use routing::scoring::Scorer;
4972         use util::logger::{Logger, Record};
4973
4974         use test::Bencher;
4975
4976         struct DummyLogger {}
4977         impl Logger for DummyLogger {
4978                 fn log(&self, _record: &Record) {}
4979         }
4980
4981         fn read_network_graph() -> NetworkGraph {
4982                 let mut d = test_utils::get_route_file().unwrap();
4983                 NetworkGraph::read(&mut d).unwrap()
4984         }
4985
4986         fn payer_pubkey() -> PublicKey {
4987                 let secp_ctx = Secp256k1::new();
4988                 PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap())
4989         }
4990
4991         #[inline]
4992         fn first_hop(node_id: PublicKey) -> ChannelDetails {
4993                 ChannelDetails {
4994                         channel_id: [0; 32],
4995                         counterparty: ChannelCounterparty {
4996                                 features: InitFeatures::known(),
4997                                 node_id,
4998                                 unspendable_punishment_reserve: 0,
4999                                 forwarding_info: None,
5000                         },
5001                         funding_txo: Some(OutPoint {
5002                                 txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0
5003                         }),
5004                         short_channel_id: Some(1),
5005                         channel_value_satoshis: 10_000_000,
5006                         user_channel_id: 0,
5007                         balance_msat: 10_000_000,
5008                         outbound_capacity_msat: 10_000_000,
5009                         inbound_capacity_msat: 0,
5010                         unspendable_punishment_reserve: None,
5011                         confirmations_required: None,
5012                         force_close_spend_delay: None,
5013                         is_outbound: true,
5014                         is_funding_locked: true,
5015                         is_usable: true,
5016                         is_public: true,
5017                 }
5018         }
5019
5020         #[bench]
5021         fn generate_routes_with_default_scorer(bench: &mut Bencher) {
5022                 let network_graph = read_network_graph();
5023                 let scorer = Scorer::default();
5024                 generate_routes(bench, &network_graph, scorer, InvoiceFeatures::empty());
5025         }
5026
5027         #[bench]
5028         fn generate_mpp_routes_with_default_scorer(bench: &mut Bencher) {
5029                 let network_graph = read_network_graph();
5030                 let scorer = Scorer::default();
5031                 generate_routes(bench, &network_graph, scorer, InvoiceFeatures::known());
5032         }
5033
5034         fn generate_routes<S: Score>(
5035                 bench: &mut Bencher, graph: &NetworkGraph, mut scorer: S, features: InvoiceFeatures
5036         ) {
5037                 let nodes = graph.read_only().nodes().clone();
5038                 let payer = payer_pubkey();
5039
5040                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
5041                 let mut routes = Vec::new();
5042                 let mut route_endpoints = Vec::new();
5043                 let mut seed: usize = 0xdeadbeef;
5044                 'load_endpoints: for _ in 0..100 {
5045                         loop {
5046                                 seed *= 0xdeadbeef;
5047                                 let src = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
5048                                 seed *= 0xdeadbeef;
5049                                 let dst = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
5050                                 let params = PaymentParameters::from_node_id(dst).with_features(features.clone());
5051                                 let first_hop = first_hop(src);
5052                                 let amt = seed as u64 % 1_000_000;
5053                                 if let Ok(route) = get_route(&payer, &params, &graph, Some(&[&first_hop]), amt, 42, &DummyLogger{}, &scorer) {
5054                                         routes.push(route);
5055                                         route_endpoints.push((first_hop, params, amt));
5056                                         continue 'load_endpoints;
5057                                 }
5058                         }
5059                 }
5060
5061                 // ...and seed the scorer with success and failure data...
5062                 for route in routes {
5063                         let amount = route.get_total_amount();
5064                         if amount < 250_000 {
5065                                 for path in route.paths {
5066                                         scorer.payment_path_successful(&path.iter().collect::<Vec<_>>());
5067                                 }
5068                         } else if amount > 750_000 {
5069                                 for path in route.paths {
5070                                         let short_channel_id = path[path.len() / 2].short_channel_id;
5071                                         scorer.payment_path_failed(&path.iter().collect::<Vec<_>>(), short_channel_id);
5072                                 }
5073                         }
5074                 }
5075
5076                 // ...then benchmark finding paths between the nodes we learned.
5077                 let mut idx = 0;
5078                 bench.iter(|| {
5079                         let (first_hop, params, amt) = &route_endpoints[idx % route_endpoints.len()];
5080                         assert!(get_route(&payer, params, &graph, Some(&[first_hop]), *amt, 42, &DummyLogger{}, &scorer).is_ok());
5081                         idx += 1;
5082                 });
5083         }
5084 }