_ 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;
  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 `payee` parameter passed to [`get_route`].
  74         /// This is used by `ChannelManager` to track information which may be required for retries,
  75         /// provided back to you via [`Event::PaymentPathFailed`].
  76         ///
  77         /// [`Event::PaymentPathFailed`]: crate::util::events::Event::PaymentPathFailed
  78         pub payee: Option<Payee>,
  79 }
  80
  81 impl Route {
  82         /// Returns the total amount of fees paid on this [`Route`].
  83         ///
  84         /// This doesn't include any extra payment made to the recipient, which can happen in excess of
  85         /// the amount passed to [`get_route`]'s `final_value_msat`.
  86         pub fn get_total_fees(&self) -> u64 {
  87                 // Do not count last hop of each path since that's the full value of the payment
  88                 return self.paths.iter()
  89                         .flat_map(|path| path.split_last().map(|(_, path_prefix)| path_prefix).unwrap_or(&[]))
  90                         .map(|hop| &hop.fee_msat)
  91                         .sum();
  92         }
  93
  94         /// Returns the total amount paid on this [`Route`], excluding the fees.
  95         pub fn get_total_amount(&self) -> u64 {
  96                 return self.paths.iter()
  97                         .map(|path| path.split_last().map(|(hop, _)| hop.fee_msat).unwrap_or(0))
  98                         .sum();
  99         }
 100 }
 101
 102 const SERIALIZATION_VERSION: u8 = 1;
 103 const MIN_SERIALIZATION_VERSION: u8 = 1;
 104
 105 impl Writeable for Route {
 106         fn write<W: ::util::ser::Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 107                 write_ver_prefix!(writer, SERIALIZATION_VERSION, MIN_SERIALIZATION_VERSION);
 108                 (self.paths.len() as u64).write(writer)?;
 109                 for hops in self.paths.iter() {
 110                         (hops.len() as u8).write(writer)?;
 111                         for hop in hops.iter() {
 112                                 hop.write(writer)?;
 113                         }
 114                 }
 115                 write_tlv_fields!(writer, {
 116                         (1, self.payee, option),
 117                 });
 118                 Ok(())
 119         }
 120 }
 121
 122 impl Readable for Route {
 123         fn read<R: io::Read>(reader: &mut R) -> Result<Route, DecodeError> {
 124                 let _ver = read_ver_prefix!(reader, SERIALIZATION_VERSION);
 125                 let path_count: u64 = Readable::read(reader)?;
 126                 let mut paths = Vec::with_capacity(cmp::min(path_count, 128) as usize);
 127                 for _ in 0..path_count {
 128                         let hop_count: u8 = Readable::read(reader)?;
 129                         let mut hops = Vec::with_capacity(hop_count as usize);
 130                         for _ in 0..hop_count {
 131                                 hops.push(Readable::read(reader)?);
 132                         }
 133                         paths.push(hops);
 134                 }
 135                 let mut payee = None;
 136                 read_tlv_fields!(reader, {
 137                         (1, payee, option),
 138                 });
 139                 Ok(Route { paths, payee })
 140         }
 141 }
 142
 143 /// Parameters needed to re-compute a [`Route`] for retrying a failed payment path.
 144 ///
 145 /// Provided in [`Event::PaymentPathFailed`] and passed to [`get_retry_route`].
 146 ///
 147 /// [`Event::PaymentPathFailed`]: crate::util::events::Event::PaymentPathFailed
 148 #[derive(Clone, Debug)]
 149 pub struct PaymentPathRetry {
 150         /// The recipient of the failed payment path.
 151         pub payee: Payee,
 152
 153         /// The amount in msats sent on the failed payment path.
 154         pub final_value_msat: u64,
 155
 156         /// The CLTV on the final hop of the failed payment path.
 157         pub final_cltv_expiry_delta: u32,
 158 }
 159
 160 impl_writeable_tlv_based!(PaymentPathRetry, {
 161         (0, payee, required),
 162         (2, final_value_msat, required),
 163         (4, final_cltv_expiry_delta, required),
 164 });
 165
 166 /// The recipient of a payment.
 167 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
 168 pub struct Payee {
 169         /// The node id of the payee.
 170         pub pubkey: PublicKey,
 171
 172         /// Features supported by the payee.
 173         ///
 174         /// May be set from the payee's invoice or via [`for_keysend`]. May be `None` if the invoice
 175         /// does not contain any features.
 176         ///
 177         /// [`for_keysend`]: Self::for_keysend
 178         pub features: Option<InvoiceFeatures>,
 179
 180         /// Hints for routing to the payee, containing channels connecting the payee to public nodes.
 181         pub route_hints: Vec<RouteHint>,
 182 }
 183
 184 impl_writeable_tlv_based!(Payee, {
 185         (0, pubkey, required),
 186         (2, features, option),
 187         (4, route_hints, vec_type),
 188 });
 189
 190 impl Payee {
 191         /// Creates a payee with the node id of the given `pubkey`.
 192         pub fn new(pubkey: PublicKey) -> Self {
 193                 Self {
 194                         pubkey,
 195                         features: None,
 196                         route_hints: vec![],
 197                 }
 198         }
 199
 200         /// Creates a payee with the node id of the given `pubkey` to use for keysend payments.
 201         pub fn for_keysend(pubkey: PublicKey) -> Self {
 202                 Self::new(pubkey).with_features(InvoiceFeatures::for_keysend())
 203         }
 204
 205         /// Includes the payee's features.
 206         ///
 207         /// (C-not exported) since bindings don't support move semantics
 208         pub fn with_features(self, features: InvoiceFeatures) -> Self {
 209                 Self { features: Some(features), ..self }
 210         }
 211
 212         /// Includes hints for routing to the payee.
 213         ///
 214         /// (C-not exported) since bindings don't support move semantics
 215         pub fn with_route_hints(self, route_hints: Vec<RouteHint>) -> Self {
 216                 Self { route_hints, ..self }
 217         }
 218 }
 219
 220 /// A list of hops along a payment path terminating with a channel to the recipient.
 221 #[derive(Clone, Debug, Hash, Eq, PartialEq)]
 222 pub struct RouteHint(pub Vec<RouteHintHop>);
 223
 224
 225 impl Writeable for RouteHint {
 226         fn write<W: ::util::ser::Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 227                 (self.0.len() as u64).write(writer)?;
 228                 for hop in self.0.iter() {
 229                         hop.write(writer)?;
 230                 }
 231                 Ok(())
 232         }
 233 }
 234
 235 impl Readable for RouteHint {
 236         fn read<R: io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
 237                 let hop_count: u64 = Readable::read(reader)?;
 238                 let mut hops = Vec::with_capacity(cmp::min(hop_count, 16) as usize);
 239                 for _ in 0..hop_count {
 240                         hops.push(Readable::read(reader)?);
 241                 }
 242                 Ok(Self(hops))
 243         }
 244 }
 245
 246 /// A channel descriptor for a hop along a payment path.
 247 #[derive(Clone, Debug, Hash, Eq, PartialEq)]
 248 pub struct RouteHintHop {
 249         /// The node_id of the non-target end of the route
 250         pub src_node_id: PublicKey,
 251         /// The short_channel_id of this channel
 252         pub short_channel_id: u64,
 253         /// The fees which must be paid to use this channel
 254         pub fees: RoutingFees,
 255         /// The difference in CLTV values between this node and the next node.
 256         pub cltv_expiry_delta: u16,
 257         /// The minimum value, in msat, which must be relayed to the next hop.
 258         pub htlc_minimum_msat: Option<u64>,
 259         /// The maximum value in msat available for routing with a single HTLC.
 260         pub htlc_maximum_msat: Option<u64>,
 261 }
 262
 263 impl_writeable_tlv_based!(RouteHintHop, {
 264         (0, src_node_id, required),
 265         (1, htlc_minimum_msat, option),
 266         (2, short_channel_id, required),
 267         (3, htlc_maximum_msat, option),
 268         (4, fees, required),
 269         (6, cltv_expiry_delta, required),
 270 });
 271
 272 #[derive(Eq, PartialEq)]
 273 struct RouteGraphNode {
 274         node_id: NodeId,
 275         lowest_fee_to_peer_through_node: u64,
 276         lowest_fee_to_node: u64,
 277         // The maximum value a yet-to-be-constructed payment path might flow through this node.
 278         // This value is upper-bounded by us by:
 279         // - how much is needed for a path being constructed
 280         // - how much value can channels following this node (up to the destination) can contribute,
 281         //   considering their capacity and fees
 282         value_contribution_msat: u64,
 283         /// The effective htlc_minimum_msat at this hop. If a later hop on the path had a higher HTLC
 284         /// minimum, we use it, plus the fees required at each earlier hop to meet it.
 285         path_htlc_minimum_msat: u64,
 286         /// All penalties incurred from this hop on the way to the destination, as calculated using
 287         /// channel scoring.
 288         path_penalty_msat: u64,
 289 }
 290
 291 impl cmp::Ord for RouteGraphNode {
 292         fn cmp(&self, other: &RouteGraphNode) -> cmp::Ordering {
 293                 let other_score = cmp::max(other.lowest_fee_to_peer_through_node, other.path_htlc_minimum_msat)
 294                         .checked_add(other.path_penalty_msat)
 295                         .unwrap_or_else(|| u64::max_value());
 296                 let self_score = cmp::max(self.lowest_fee_to_peer_through_node, self.path_htlc_minimum_msat)
 297                         .checked_add(self.path_penalty_msat)
 298                         .unwrap_or_else(|| u64::max_value());
 299                 other_score.cmp(&self_score).then_with(|| other.node_id.cmp(&self.node_id))
 300         }
 301 }
 302
 303 impl cmp::PartialOrd for RouteGraphNode {
 304         fn partial_cmp(&self, other: &RouteGraphNode) -> Option<cmp::Ordering> {
 305                 Some(self.cmp(other))
 306         }
 307 }
 308
 309 struct DummyDirectionalChannelInfo {
 310         cltv_expiry_delta: u32,
 311         htlc_minimum_msat: u64,
 312         htlc_maximum_msat: Option<u64>,
 313         fees: RoutingFees,
 314 }
 315
 316 /// It's useful to keep track of the hops associated with the fees required to use them,
 317 /// so that we can choose cheaper paths (as per Dijkstra's algorithm).
 318 /// Fee values should be updated only in the context of the whole path, see update_value_and_recompute_fees.
 319 /// These fee values are useful to choose hops as we traverse the graph "payee-to-payer".
 320 #[derive(Clone, Debug)]
 321 struct PathBuildingHop<'a> {
 322         // The RouteHintHop fields which will eventually be used if this hop is used in a final Route.
 323         // Note that node_features is calculated separately after our initial graph walk.
 324         node_id: NodeId,
 325         short_channel_id: u64,
 326         channel_features: &'a ChannelFeatures,
 327         fee_msat: u64,
 328         cltv_expiry_delta: u32,
 329
 330         /// Minimal fees required to route to the source node of the current hop via any of its inbound channels.
 331         src_lowest_inbound_fees: RoutingFees,
 332         /// Fees of the channel used in this hop.
 333         channel_fees: RoutingFees,
 334         /// All the fees paid *after* this channel on the way to the destination
 335         next_hops_fee_msat: u64,
 336         /// Fee paid for the use of the current channel (see channel_fees).
 337         /// The value will be actually deducted from the counterparty balance on the previous link.
 338         hop_use_fee_msat: u64,
 339         /// Used to compare channels when choosing the for routing.
 340         /// Includes paying for the use of a hop and the following hops, as well as
 341         /// an estimated cost of reaching this hop.
 342         /// Might get stale when fees are recomputed. Primarily for internal use.
 343         total_fee_msat: u64,
 344         /// This is useful for update_value_and_recompute_fees to make sure
 345         /// we don't fall below the minimum. Should not be updated manually and
 346         /// generally should not be accessed.
 347         htlc_minimum_msat: u64,
 348         /// A mirror of the same field in RouteGraphNode. Note that this is only used during the graph
 349         /// walk and may be invalid thereafter.
 350         path_htlc_minimum_msat: u64,
 351         /// All penalties incurred from this channel on the way to the destination, as calculated using
 352         /// channel scoring.
 353         path_penalty_msat: u64,
 354         /// If we've already processed a node as the best node, we shouldn't process it again. Normally
 355         /// we'd just ignore it if we did as all channels would have a higher new fee, but because we
 356         /// may decrease the amounts in use as we walk the graph, the actual calculated fee may
 357         /// decrease as well. Thus, we have to explicitly track which nodes have been processed and
 358         /// avoid processing them again.
 359         was_processed: bool,
 360         #[cfg(any(test, feature = "fuzztarget"))]
 361         // In tests, we apply further sanity checks on cases where we skip nodes we already processed
 362         // to ensure it is specifically in cases where the fee has gone down because of a decrease in
 363         // value_contribution_msat, which requires tracking it here. See comments below where it is
 364         // used for more info.
 365         value_contribution_msat: u64,
 366 }
 367
 368 // Instantiated with a list of hops with correct data in them collected during path finding,
 369 // an instance of this struct should be further modified only via given methods.
 370 #[derive(Clone)]
 371 struct PaymentPath<'a> {
 372         hops: Vec<(PathBuildingHop<'a>, NodeFeatures)>,
 373 }
 374
 375 impl<'a> PaymentPath<'a> {
 376         // TODO: Add a value_msat field to PaymentPath and use it instead of this function.
 377         fn get_value_msat(&self) -> u64 {
 378                 self.hops.last().unwrap().0.fee_msat
 379         }
 380
 381         fn get_total_fee_paid_msat(&self) -> u64 {
 382                 if self.hops.len() < 1 {
 383                         return 0;
 384                 }
 385                 let mut result = 0;
 386                 // Can't use next_hops_fee_msat because it gets outdated.
 387                 for (i, (hop, _)) in self.hops.iter().enumerate() {
 388                         if i != self.hops.len() - 1 {
 389                                 result += hop.fee_msat;
 390                         }
 391                 }
 392                 return result;
 393         }
 394
 395         // If the amount transferred by the path is updated, the fees should be adjusted. Any other way
 396         // to change fees may result in an inconsistency.
 397         //
 398         // Sometimes we call this function right after constructing a path which is inconsistent in
 399         // that it the value being transferred has decreased while we were doing path finding, leading
 400         // to the fees being paid not lining up with the actual limits.
 401         //
 402         // Note that this function is not aware of the available_liquidity limit, and thus does not
 403         // support increasing the value being transferred.
 404         fn update_value_and_recompute_fees(&mut self, value_msat: u64) {
 405                 assert!(value_msat <= self.hops.last().unwrap().0.fee_msat);
 406
 407                 let mut total_fee_paid_msat = 0 as u64;
 408                 for i in (0..self.hops.len()).rev() {
 409                         let last_hop = i == self.hops.len() - 1;
 410
 411                         // For non-last-hop, this value will represent the fees paid on the current hop. It
 412                         // will consist of the fees for the use of the next hop, and extra fees to match
 413                         // htlc_minimum_msat of the current channel. Last hop is handled separately.
 414                         let mut cur_hop_fees_msat = 0;
 415                         if !last_hop {
 416                                 cur_hop_fees_msat = self.hops.get(i + 1).unwrap().0.hop_use_fee_msat;
 417                         }
 418
 419                         let mut cur_hop = &mut self.hops.get_mut(i).unwrap().0;
 420                         cur_hop.next_hops_fee_msat = total_fee_paid_msat;
 421                         // Overpay in fees if we can't save these funds due to htlc_minimum_msat.
 422                         // We try to account for htlc_minimum_msat in scoring (add_entry!), so that nodes don't
 423                         // set it too high just to maliciously take more fees by exploiting this
 424                         // match htlc_minimum_msat logic.
 425                         let mut cur_hop_transferred_amount_msat = total_fee_paid_msat + value_msat;
 426                         if let Some(extra_fees_msat) = cur_hop.htlc_minimum_msat.checked_sub(cur_hop_transferred_amount_msat) {
 427                                 // Note that there is a risk that *previous hops* (those closer to us, as we go
 428                                 // payee->our_node here) would exceed their htlc_maximum_msat or available balance.
 429                                 //
 430                                 // This might make us end up with a broken route, although this should be super-rare
 431                                 // in practice, both because of how healthy channels look like, and how we pick
 432                                 // channels in add_entry.
 433                                 // Also, this can't be exploited more heavily than *announce a free path and fail
 434                                 // all payments*.
 435                                 cur_hop_transferred_amount_msat += extra_fees_msat;
 436                                 total_fee_paid_msat += extra_fees_msat;
 437                                 cur_hop_fees_msat += extra_fees_msat;
 438                         }
 439
 440                         if last_hop {
 441                                 // Final hop is a special case: it usually has just value_msat (by design), but also
 442                                 // it still could overpay for the htlc_minimum_msat.
 443                                 cur_hop.fee_msat = cur_hop_transferred_amount_msat;
 444                         } else {
 445                                 // Propagate updated fees for the use of the channels to one hop back, where they
 446                                 // will be actually paid (fee_msat). The last hop is handled above separately.
 447                                 cur_hop.fee_msat = cur_hop_fees_msat;
 448                         }
 449
 450                         // Fee for the use of the current hop which will be deducted on the previous hop.
 451                         // Irrelevant for the first hop, as it doesn't have the previous hop, and the use of
 452                         // this channel is free for us.
 453                         if i != 0 {
 454                                 if let Some(new_fee) = compute_fees(cur_hop_transferred_amount_msat, cur_hop.channel_fees) {
 455                                         cur_hop.hop_use_fee_msat = new_fee;
 456                                         total_fee_paid_msat += new_fee;
 457                                 } else {
 458                                         // It should not be possible because this function is called only to reduce the
 459                                         // value. In that case, compute_fee was already called with the same fees for
 460                                         // larger amount and there was no overflow.
 461                                         unreachable!();
 462                                 }
 463                         }
 464                 }
 465         }
 466 }
 467
 468 fn compute_fees(amount_msat: u64, channel_fees: RoutingFees) -> Option<u64> {
 469         let proportional_fee_millions =
 470                 amount_msat.checked_mul(channel_fees.proportional_millionths as u64);
 471         if let Some(new_fee) = proportional_fee_millions.and_then(|part| {
 472                         (channel_fees.base_msat as u64).checked_add(part / 1_000_000) }) {
 473
 474                 Some(new_fee)
 475         } else {
 476                 // This function may be (indirectly) called without any verification,
 477                 // with channel_fees provided by a caller. We should handle it gracefully.
 478                 None
 479         }
 480 }
 481
 482 /// Gets a keysend route from us (payer) to the given target node (payee). This is needed because
 483 /// keysend payments do not have an invoice from which to pull the payee's supported features, which
 484 /// makes it tricky to otherwise supply the `payee` parameter of `get_route`.
 485 pub fn get_keysend_route<L: Deref, S: routing::Score>(
 486         our_node_pubkey: &PublicKey, network: &NetworkGraph, payee: &PublicKey,
 487         first_hops: Option<&[&ChannelDetails]>, last_hops: &[&RouteHint], final_value_msat: u64,
 488         final_cltv_expiry_delta: u32, logger: L, scorer: &S
 489 ) -> Result<Route, LightningError>
 490 where L::Target: Logger {
 491         let route_hints = last_hops.iter().map(|hint| (*hint).clone()).collect();
 492         let payee = Payee::for_keysend(*payee).with_route_hints(route_hints);
 493         get_route(
 494                 our_node_pubkey, &payee, network, first_hops, final_value_msat, final_cltv_expiry_delta,
 495                 logger, scorer
 496         )
 497 }
 498
 499 /// Gets a route suitable for retrying a failed payment path.
 500 ///
 501 /// Used to re-compute a [`Route`] when handling a [`Event::PaymentPathFailed`]. Any adjustments to
 502 /// the [`NetworkGraph`] and channel scores should be made prior to calling this function.
 503 ///
 504 /// [`Event::PaymentPathFailed`]: crate::util::events::Event::PaymentPathFailed
 505 pub fn get_retry_route<L: Deref, S: routing::Score>(
 506         our_node_pubkey: &PublicKey, retry: &PaymentPathRetry, network: &NetworkGraph,
 507         first_hops: Option<&[&ChannelDetails]>, logger: L, scorer: &S
 508 ) -> Result<Route, LightningError>
 509 where L::Target: Logger {
 510         get_route(
 511                 our_node_pubkey, &retry.payee, network, first_hops, retry.final_value_msat,
 512                 retry.final_cltv_expiry_delta, logger, scorer
 513         )
 514 }
 515
 516 /// Gets a route from us (payer) to the given target node (payee).
 517 ///
 518 /// If the payee provided features in their invoice, they should be provided via `payee`.  Without
 519 /// this, MPP will only be used if the payee's features are available in the network graph.
 520 ///
 521 /// Private routing paths between a public node and the target may be included in `payee`.
 522 ///
 523 /// If some channels aren't announced, it may be useful to fill in a first_hops with the
 524 /// results from a local ChannelManager::list_usable_channels() call. If it is filled in, our
 525 /// view of our local channels (from net_graph_msg_handler) will be ignored, and only those
 526 /// in first_hops will be used.
 527 ///
 528 /// Panics if first_hops contains channels without short_channel_ids
 529 /// (ChannelManager::list_usable_channels will never include such channels).
 530 ///
 531 /// The fees on channels from us to next-hops are ignored (as they are assumed to all be
 532 /// equal), however the enabled/disabled bit on such channels as well as the
 533 /// htlc_minimum_msat/htlc_maximum_msat *are* checked as they may change based on the receiving node.
 534 pub fn get_route<L: Deref, S: routing::Score>(
 535         our_node_pubkey: &PublicKey, payee: &Payee, network: &NetworkGraph,
 536         first_hops: Option<&[&ChannelDetails]>, final_value_msat: u64, final_cltv_expiry_delta: u32,
 537         logger: L, scorer: &S
 538 ) -> Result<Route, LightningError>
 539 where L::Target: Logger {
 540         let payee_node_id = NodeId::from_pubkey(&payee.pubkey);
 541         let our_node_id = NodeId::from_pubkey(&our_node_pubkey);
 542
 543         if payee_node_id == our_node_id {
 544                 return Err(LightningError{err: "Cannot generate a route to ourselves".to_owned(), action: ErrorAction::IgnoreError});
 545         }
 546
 547         if final_value_msat > MAX_VALUE_MSAT {
 548                 return Err(LightningError{err: "Cannot generate a route of more value than all existing satoshis".to_owned(), action: ErrorAction::IgnoreError});
 549         }
 550
 551         if final_value_msat == 0 {
 552                 return Err(LightningError{err: "Cannot send a payment of 0 msat".to_owned(), action: ErrorAction::IgnoreError});
 553         }
 554
 555         for route in payee.route_hints.iter() {
 556                 for hop in &route.0 {
 557                         if hop.src_node_id == payee.pubkey {
 558                                 return Err(LightningError{err: "Route hint cannot have the payee as the source.".to_owned(), action: ErrorAction::IgnoreError});
 559                         }
 560                 }
 561         }
 562
 563         // The general routing idea is the following:
 564         // 1. Fill first/last hops communicated by the caller.
 565         // 2. Attempt to construct a path from payer to payee for transferring
 566         //    any ~sufficient (described later) value.
 567         //    If succeed, remember which channels were used and how much liquidity they have available,
 568         //    so that future paths don't rely on the same liquidity.
 569         // 3. Prooceed to the next step if:
 570         //    - we hit the recommended target value;
 571         //    - OR if we could not construct a new path. Any next attempt will fail too.
 572         //    Otherwise, repeat step 2.
 573         // 4. See if we managed to collect paths which aggregately are able to transfer target value
 574         //    (not recommended value). If yes, proceed. If not, fail routing.
 575         // 5. Randomly combine paths into routes having enough to fulfill the payment. (TODO: knapsack)
 576         // 6. Of all the found paths, select only those with the lowest total fee.
 577         // 7. The last path in every selected route is likely to be more than we need.
 578         //    Reduce its value-to-transfer and recompute fees.
 579         // 8. Choose the best route by the lowest total fee.
 580
 581         // As for the actual search algorithm,
 582         // we do a payee-to-payer pseudo-Dijkstra's sorting by each node's distance from the payee
 583         // plus the minimum per-HTLC fee to get from it to another node (aka "shitty pseudo-A*").
 584         //
 585         // We are not a faithful Dijkstra's implementation because we can change values which impact
 586         // earlier nodes while processing later nodes. Specifically, if we reach a channel with a lower
 587         // liquidity limit (via htlc_maximum_msat, on-chain capacity or assumed liquidity limits) then
 588         // the value we are currently attempting to send over a path, we simply reduce the value being
 589         // sent along the path for any hops after that channel. This may imply that later fees (which
 590         // we've already tabulated) are lower because a smaller value is passing through the channels
 591         // (and the proportional fee is thus lower). There isn't a trivial way to recalculate the
 592         // channels which were selected earlier (and which may still be used for other paths without a
 593         // lower liquidity limit), so we simply accept that some liquidity-limited paths may be
 594         // de-preferenced.
 595         //
 596         // One potentially problematic case for this algorithm would be if there are many
 597         // liquidity-limited paths which are liquidity-limited near the destination (ie early in our
 598         // graph walking), we may never find a path which is not liquidity-limited and has lower
 599         // proportional fee (and only lower absolute fee when considering the ultimate value sent).
 600         // Because we only consider paths with at least 5% of the total value being sent, the damage
 601         // from such a case should be limited, however this could be further reduced in the future by
 602         // calculating fees on the amount we wish to route over a path, ie ignoring the liquidity
 603         // limits for the purposes of fee calculation.
 604         //
 605         // Alternatively, we could store more detailed path information in the heap (targets, below)
 606         // and index the best-path map (dist, below) by node *and* HTLC limits, however that would blow
 607         // up the runtime significantly both algorithmically (as we'd traverse nodes multiple times)
 608         // and practically (as we would need to store dynamically-allocated path information in heap
 609         // objects, increasing malloc traffic and indirect memory access significantly). Further, the
 610         // results of such an algorithm would likely be biased towards lower-value paths.
 611         //
 612         // Further, we could return to a faithful Dijkstra's algorithm by rejecting paths with limits
 613         // outside of our current search value, running a path search more times to gather candidate
 614         // paths at different values. While this may be acceptable, further path searches may increase
 615         // runtime for little gain. Specifically, the current algorithm rather efficiently explores the
 616         // graph for candidate paths, calculating the maximum value which can realistically be sent at
 617         // the same time, remaining generic across different payment values.
 618         //
 619         // TODO: There are a few tweaks we could do, including possibly pre-calculating more stuff
 620         // to use as the A* heuristic beyond just the cost to get one node further than the current
 621         // one.
 622
 623         let network_graph = network.read_only();
 624         let network_channels = network_graph.channels();
 625         let network_nodes = network_graph.nodes();
 626         let dummy_directional_info = DummyDirectionalChannelInfo { // used for first_hops routes
 627                 cltv_expiry_delta: 0,
 628                 htlc_minimum_msat: 0,
 629                 htlc_maximum_msat: None,
 630                 fees: RoutingFees {
 631                         base_msat: 0,
 632                         proportional_millionths: 0,
 633                 }
 634         };
 635
 636         // Allow MPP only if we have a features set from somewhere that indicates the payee supports
 637         // it. If the payee supports it they're supposed to include it in the invoice, so that should
 638         // work reliably.
 639         let allow_mpp = if let Some(features) = &payee.features {
 640                 features.supports_basic_mpp()
 641         } else if let Some(node) = network_nodes.get(&payee_node_id) {
 642                 if let Some(node_info) = node.announcement_info.as_ref() {
 643                         node_info.features.supports_basic_mpp()
 644                 } else { false }
 645         } else { false };
 646         log_trace!(logger, "Searching for a route from payer {} to payee {} {} MPP", our_node_pubkey,
 647                 payee.pubkey, if allow_mpp { "with" } else { "without" });
 648
 649         // Step (1).
 650         // Prepare the data we'll use for payee-to-payer search by
 651         // inserting first hops suggested by the caller as targets.
 652         // Our search will then attempt to reach them while traversing from the payee node.
 653         let mut first_hop_targets: HashMap<_, Vec<(_, ChannelFeatures, _, NodeFeatures)>> =
 654                 HashMap::with_capacity(if first_hops.is_some() { first_hops.as_ref().unwrap().len() } else { 0 });
 655         if let Some(hops) = first_hops {
 656                 for chan in hops {
 657                         let short_channel_id = chan.short_channel_id.expect("first_hops should be filled in with usable channels, not pending ones");
 658                         if chan.counterparty.node_id == *our_node_pubkey {
 659                                 return Err(LightningError{err: "First hop cannot have our_node_pubkey as a destination.".to_owned(), action: ErrorAction::IgnoreError});
 660                         }
 661                         first_hop_targets.entry(NodeId::from_pubkey(&chan.counterparty.node_id)).or_insert(Vec::new())
 662                                 .push((short_channel_id, chan.counterparty.features.to_context(), chan.outbound_capacity_msat, chan.counterparty.features.to_context()));
 663                 }
 664                 if first_hop_targets.is_empty() {
 665                         return Err(LightningError{err: "Cannot route when there are no outbound routes away from us".to_owned(), action: ErrorAction::IgnoreError});
 666                 }
 667         }
 668
 669         let empty_channel_features = ChannelFeatures::empty();
 670
 671         // The main heap containing all candidate next-hops sorted by their score (max(A* fee,
 672         // htlc_minimum)). Ideally this would be a heap which allowed cheap score reduction instead of
 673         // adding duplicate entries when we find a better path to a given node.
 674         let mut targets = BinaryHeap::new();
 675
 676         // Map from node_id to information about the best current path to that node, including feerate
 677         // information.
 678         let mut dist = HashMap::with_capacity(network_nodes.len());
 679
 680         // During routing, if we ignore a path due to an htlc_minimum_msat limit, we set this,
 681         // indicating that we may wish to try again with a higher value, potentially paying to meet an
 682         // htlc_minimum with extra fees while still finding a cheaper path.
 683         let mut hit_minimum_limit;
 684
 685         // When arranging a route, we select multiple paths so that we can make a multi-path payment.
 686         // We start with a path_value of the exact amount we want, and if that generates a route we may
 687         // return it immediately. Otherwise, we don't stop searching for paths until we have 3x the
 688         // amount we want in total across paths, selecting the best subset at the end.
 689         const ROUTE_CAPACITY_PROVISION_FACTOR: u64 = 3;
 690         let recommended_value_msat = final_value_msat * ROUTE_CAPACITY_PROVISION_FACTOR as u64;
 691         let mut path_value_msat = final_value_msat;
 692
 693         // We don't want multiple paths (as per MPP) share liquidity of the same channels.
 694         // This map allows paths to be aware of the channel use by other paths in the same call.
 695         // This would help to make a better path finding decisions and not "overbook" channels.
 696         // It is unaware of the directions (except for `outbound_capacity_msat` in `first_hops`).
 697         let mut bookkeeped_channels_liquidity_available_msat = HashMap::with_capacity(network_nodes.len());
 698
 699         // Keeping track of how much value we already collected across other paths. Helps to decide:
 700         // - how much a new path should be transferring (upper bound);
 701         // - whether a channel should be disregarded because
 702         //   it's available liquidity is too small comparing to how much more we need to collect;
 703         // - when we want to stop looking for new paths.
 704         let mut already_collected_value_msat = 0;
 705
 706         log_trace!(logger, "Building path from {} (payee) to {} (us/payer) for value {} msat.", payee.pubkey, our_node_pubkey, final_value_msat);
 707
 708         macro_rules! add_entry {
 709                 // Adds entry which goes from $src_node_id to $dest_node_id
 710                 // over the channel with id $chan_id with fees described in
 711                 // $directional_info.
 712                 // $next_hops_fee_msat represents the fees paid for using all the channel *after* this one,
 713                 // since that value has to be transferred over this channel.
 714                 // Returns whether this channel caused an update to `targets`.
 715                 ( $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,
 716                    $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr, $next_hops_path_penalty_msat: expr ) => { {
 717                         // We "return" whether we updated the path at the end, via this:
 718                         let mut did_add_update_path_to_src_node = false;
 719                         // Channels to self should not be used. This is more of belt-and-suspenders, because in
 720                         // practice these cases should be caught earlier:
 721                         // - for regular channels at channel announcement (TODO)
 722                         // - for first and last hops early in get_route
 723                         if $src_node_id != $dest_node_id.clone() {
 724                                 let available_liquidity_msat = bookkeeped_channels_liquidity_available_msat.entry($chan_id.clone()).or_insert_with(|| {
 725                                         let mut initial_liquidity_available_msat = None;
 726                                         if let Some(capacity_sats) = $capacity_sats {
 727                                                 initial_liquidity_available_msat = Some(capacity_sats * 1000);
 728                                         }
 729
 730                                         if let Some(htlc_maximum_msat) = $directional_info.htlc_maximum_msat {
 731                                                 if let Some(available_msat) = initial_liquidity_available_msat {
 732                                                         initial_liquidity_available_msat = Some(cmp::min(available_msat, htlc_maximum_msat));
 733                                                 } else {
 734                                                         initial_liquidity_available_msat = Some(htlc_maximum_msat);
 735                                                 }
 736                                         }
 737
 738                                         match initial_liquidity_available_msat {
 739                                                 Some(available_msat) => available_msat,
 740                                                 // We assume channels with unknown balance have
 741                                                 // a capacity of 0.0025 BTC (or 250_000 sats).
 742                                                 None => 250_000 * 1000
 743                                         }
 744                                 });
 745
 746                                 // It is tricky to substract $next_hops_fee_msat from available liquidity here.
 747                                 // It may be misleading because we might later choose to reduce the value transferred
 748                                 // over these channels, and the channel which was insufficient might become sufficient.
 749                                 // Worst case: we drop a good channel here because it can't cover the high following
 750                                 // fees caused by one expensive channel, but then this channel could have been used
 751                                 // if the amount being transferred over this path is lower.
 752                                 // We do this for now, but this is a subject for removal.
 753                                 if let Some(available_value_contribution_msat) = available_liquidity_msat.checked_sub($next_hops_fee_msat) {
 754
 755                                         // Routing Fragmentation Mitigation heuristic:
 756                                         //
 757                                         // Routing fragmentation across many payment paths increases the overall routing
 758                                         // fees as you have irreducible routing fees per-link used (`fee_base_msat`).
 759                                         // Taking too many smaller paths also increases the chance of payment failure.
 760                                         // Thus to avoid this effect, we require from our collected links to provide
 761                                         // at least a minimal contribution to the recommended value yet-to-be-fulfilled.
 762                                         //
 763                                         // This requirement is currently 5% of the remaining-to-be-collected value.
 764                                         // This means as we successfully advance in our collection,
 765                                         // the absolute liquidity contribution is lowered,
 766                                         // thus increasing the number of potential channels to be selected.
 767
 768                                         // Derive the minimal liquidity contribution with a ratio of 20 (5%, rounded up)
 769                                         // or 100% if we're not allowed to do multipath payments.
 770                                         let minimal_value_contribution_msat: u64 = if allow_mpp {
 771                                                 (recommended_value_msat - already_collected_value_msat + 19) / 20
 772                                         } else {
 773                                                 final_value_msat
 774                                         };
 775                                         // Verify the liquidity offered by this channel complies to the minimal contribution.
 776                                         let contributes_sufficient_value = available_value_contribution_msat >= minimal_value_contribution_msat;
 777
 778                                         let value_contribution_msat = cmp::min(available_value_contribution_msat, $next_hops_value_contribution);
 779                                         // Includes paying fees for the use of the following channels.
 780                                         let amount_to_transfer_over_msat: u64 = match value_contribution_msat.checked_add($next_hops_fee_msat) {
 781                                                 Some(result) => result,
 782                                                 // Can't overflow due to how the values were computed right above.
 783                                                 None => unreachable!(),
 784                                         };
 785                                         #[allow(unused_comparisons)] // $next_hops_path_htlc_minimum_msat is 0 in some calls so rustc complains
 786                                         let over_path_minimum_msat = amount_to_transfer_over_msat >= $directional_info.htlc_minimum_msat &&
 787                                                 amount_to_transfer_over_msat >= $next_hops_path_htlc_minimum_msat;
 788
 789                                         // If HTLC minimum is larger than the amount we're going to transfer, we shouldn't
 790                                         // bother considering this channel.
 791                                         // Since we're choosing amount_to_transfer_over_msat as maximum possible, it can
 792                                         // be only reduced later (not increased), so this channel should just be skipped
 793                                         // as not sufficient.
 794                                         if !over_path_minimum_msat {
 795                                                 hit_minimum_limit = true;
 796                                         } else if contributes_sufficient_value {
 797                                                 // Note that low contribution here (limited by available_liquidity_msat)
 798                                                 // might violate htlc_minimum_msat on the hops which are next along the
 799                                                 // payment path (upstream to the payee). To avoid that, we recompute path
 800                                                 // path fees knowing the final path contribution after constructing it.
 801                                                 let path_htlc_minimum_msat = compute_fees($next_hops_path_htlc_minimum_msat, $directional_info.fees)
 802                                                         .and_then(|fee_msat| fee_msat.checked_add($next_hops_path_htlc_minimum_msat))
 803                                                         .map(|fee_msat| cmp::max(fee_msat, $directional_info.htlc_minimum_msat))
 804                                                         .unwrap_or_else(|| u64::max_value());
 805                                                 let hm_entry = dist.entry($src_node_id);
 806                                                 let old_entry = hm_entry.or_insert_with(|| {
 807                                                         // If there was previously no known way to access
 808                                                         // the source node (recall it goes payee-to-payer) of $chan_id, first add
 809                                                         // a semi-dummy record just to compute the fees to reach the source node.
 810                                                         // This will affect our decision on selecting $chan_id
 811                                                         // as a way to reach the $dest_node_id.
 812                                                         let mut fee_base_msat = u32::max_value();
 813                                                         let mut fee_proportional_millionths = u32::max_value();
 814                                                         if let Some(Some(fees)) = network_nodes.get(&$src_node_id).map(|node| node.lowest_inbound_channel_fees) {
 815                                                                 fee_base_msat = fees.base_msat;
 816                                                                 fee_proportional_millionths = fees.proportional_millionths;
 817                                                         }
 818                                                         PathBuildingHop {
 819                                                                 node_id: $dest_node_id.clone(),
 820                                                                 short_channel_id: 0,
 821                                                                 channel_features: $chan_features,
 822                                                                 fee_msat: 0,
 823                                                                 cltv_expiry_delta: 0,
 824                                                                 src_lowest_inbound_fees: RoutingFees {
 825                                                                         base_msat: fee_base_msat,
 826                                                                         proportional_millionths: fee_proportional_millionths,
 827                                                                 },
 828                                                                 channel_fees: $directional_info.fees,
 829                                                                 next_hops_fee_msat: u64::max_value(),
 830                                                                 hop_use_fee_msat: u64::max_value(),
 831                                                                 total_fee_msat: u64::max_value(),
 832                                                                 htlc_minimum_msat: $directional_info.htlc_minimum_msat,
 833                                                                 path_htlc_minimum_msat,
 834                                                                 path_penalty_msat: u64::max_value(),
 835                                                                 was_processed: false,
 836                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 837                                                                 value_contribution_msat,
 838                                                         }
 839                                                 });
 840
 841                                                 #[allow(unused_mut)] // We only use the mut in cfg(test)
 842                                                 let mut should_process = !old_entry.was_processed;
 843                                                 #[cfg(any(test, feature = "fuzztarget"))]
 844                                                 {
 845                                                         // In test/fuzzing builds, we do extra checks to make sure the skipping
 846                                                         // of already-seen nodes only happens in cases we expect (see below).
 847                                                         if !should_process { should_process = true; }
 848                                                 }
 849
 850                                                 if should_process {
 851                                                         let mut hop_use_fee_msat = 0;
 852                                                         let mut total_fee_msat = $next_hops_fee_msat;
 853
 854                                                         // Ignore hop_use_fee_msat for channel-from-us as we assume all channels-from-us
 855                                                         // will have the same effective-fee
 856                                                         if $src_node_id != our_node_id {
 857                                                                 match compute_fees(amount_to_transfer_over_msat, $directional_info.fees) {
 858                                                                         // max_value means we'll always fail
 859                                                                         // the old_entry.total_fee_msat > total_fee_msat check
 860                                                                         None => total_fee_msat = u64::max_value(),
 861                                                                         Some(fee_msat) => {
 862                                                                                 hop_use_fee_msat = fee_msat;
 863                                                                                 total_fee_msat += hop_use_fee_msat;
 864                                                                                 // When calculating the lowest inbound fees to a node, we
 865                                                                                 // calculate fees here not based on the actual value we think
 866                                                                                 // will flow over this channel, but on the minimum value that
 867                                                                                 // we'll accept flowing over it. The minimum accepted value
 868                                                                                 // is a constant through each path collection run, ensuring
 869                                                                                 // consistent basis. Otherwise we may later find a
 870                                                                                 // different path to the source node that is more expensive,
 871                                                                                 // but which we consider to be cheaper because we are capacity
 872                                                                                 // constrained and the relative fee becomes lower.
 873                                                                                 match compute_fees(minimal_value_contribution_msat, old_entry.src_lowest_inbound_fees)
 874                                                                                                 .map(|a| a.checked_add(total_fee_msat)) {
 875                                                                                         Some(Some(v)) => {
 876                                                                                                 total_fee_msat = v;
 877                                                                                         },
 878                                                                                         _ => {
 879                                                                                                 total_fee_msat = u64::max_value();
 880                                                                                         }
 881                                                                                 };
 882                                                                         }
 883                                                                 }
 884                                                         }
 885
 886                                                         let path_penalty_msat = $next_hops_path_penalty_msat
 887                                                                 .checked_add(scorer.channel_penalty_msat($chan_id.clone(), &$src_node_id, &$dest_node_id))
 888                                                                 .unwrap_or_else(|| u64::max_value());
 889                                                         let new_graph_node = RouteGraphNode {
 890                                                                 node_id: $src_node_id,
 891                                                                 lowest_fee_to_peer_through_node: total_fee_msat,
 892                                                                 lowest_fee_to_node: $next_hops_fee_msat as u64 + hop_use_fee_msat,
 893                                                                 value_contribution_msat: value_contribution_msat,
 894                                                                 path_htlc_minimum_msat,
 895                                                                 path_penalty_msat,
 896                                                         };
 897
 898                                                         // Update the way of reaching $src_node_id with the given $chan_id (from $dest_node_id),
 899                                                         // if this way is cheaper than the already known
 900                                                         // (considering the cost to "reach" this channel from the route destination,
 901                                                         // the cost of using this channel,
 902                                                         // and the cost of routing to the source node of this channel).
 903                                                         // Also, consider that htlc_minimum_msat_difference, because we might end up
 904                                                         // paying it. Consider the following exploit:
 905                                                         // we use 2 paths to transfer 1.5 BTC. One of them is 0-fee normal 1 BTC path,
 906                                                         // and for the other one we picked a 1sat-fee path with htlc_minimum_msat of
 907                                                         // 1 BTC. Now, since the latter is more expensive, we gonna try to cut it
 908                                                         // by 0.5 BTC, but then match htlc_minimum_msat by paying a fee of 0.5 BTC
 909                                                         // to this channel.
 910                                                         // Ideally the scoring could be smarter (e.g. 0.5*htlc_minimum_msat here),
 911                                                         // but it may require additional tracking - we don't want to double-count
 912                                                         // the fees included in $next_hops_path_htlc_minimum_msat, but also
 913                                                         // can't use something that may decrease on future hops.
 914                                                         let old_cost = cmp::max(old_entry.total_fee_msat, old_entry.path_htlc_minimum_msat)
 915                                                                 .checked_add(old_entry.path_penalty_msat)
 916                                                                 .unwrap_or_else(|| u64::max_value());
 917                                                         let new_cost = cmp::max(total_fee_msat, path_htlc_minimum_msat)
 918                                                                 .checked_add(path_penalty_msat)
 919                                                                 .unwrap_or_else(|| u64::max_value());
 920
 921                                                         if !old_entry.was_processed && new_cost < old_cost {
 922                                                                 targets.push(new_graph_node);
 923                                                                 old_entry.next_hops_fee_msat = $next_hops_fee_msat;
 924                                                                 old_entry.hop_use_fee_msat = hop_use_fee_msat;
 925                                                                 old_entry.total_fee_msat = total_fee_msat;
 926                                                                 old_entry.node_id = $dest_node_id.clone();
 927                                                                 old_entry.short_channel_id = $chan_id.clone();
 928                                                                 old_entry.channel_features = $chan_features;
 929                                                                 old_entry.fee_msat = 0; // This value will be later filled with hop_use_fee_msat of the following channel
 930                                                                 old_entry.cltv_expiry_delta = $directional_info.cltv_expiry_delta as u32;
 931                                                                 old_entry.channel_fees = $directional_info.fees;
 932                                                                 old_entry.htlc_minimum_msat = $directional_info.htlc_minimum_msat;
 933                                                                 old_entry.path_htlc_minimum_msat = path_htlc_minimum_msat;
 934                                                                 old_entry.path_penalty_msat = path_penalty_msat;
 935                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 936                                                                 {
 937                                                                         old_entry.value_contribution_msat = value_contribution_msat;
 938                                                                 }
 939                                                                 did_add_update_path_to_src_node = true;
 940                                                         } else if old_entry.was_processed && new_cost < old_cost {
 941                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 942                                                                 {
 943                                                                         // If we're skipping processing a node which was previously
 944                                                                         // processed even though we found another path to it with a
 945                                                                         // cheaper fee, check that it was because the second path we
 946                                                                         // found (which we are processing now) has a lower value
 947                                                                         // contribution due to an HTLC minimum limit.
 948                                                                         //
 949                                                                         // e.g. take a graph with two paths from node 1 to node 2, one
 950                                                                         // through channel A, and one through channel B. Channel A and
 951                                                                         // B are both in the to-process heap, with their scores set by
 952                                                                         // a higher htlc_minimum than fee.
 953                                                                         // Channel A is processed first, and the channels onwards from
 954                                                                         // node 1 are added to the to-process heap. Thereafter, we pop
 955                                                                         // Channel B off of the heap, note that it has a much more
 956                                                                         // restrictive htlc_maximum_msat, and recalculate the fees for
 957                                                                         // all of node 1's channels using the new, reduced, amount.
 958                                                                         //
 959                                                                         // This would be bogus - we'd be selecting a higher-fee path
 960                                                                         // with a lower htlc_maximum_msat instead of the one we'd
 961                                                                         // already decided to use.
 962                                                                         debug_assert!(path_htlc_minimum_msat < old_entry.path_htlc_minimum_msat);
 963                                                                         debug_assert!(
 964                                                                                 value_contribution_msat + path_penalty_msat <
 965                                                                                 old_entry.value_contribution_msat + old_entry.path_penalty_msat
 966                                                                         );
 967                                                                 }
 968                                                         }
 969                                                 }
 970                                         }
 971                                 }
 972                         }
 973                         did_add_update_path_to_src_node
 974                 } }
 975         }
 976
 977         let empty_node_features = NodeFeatures::empty();
 978         // Find ways (channels with destination) to reach a given node and store them
 979         // in the corresponding data structures (routing graph etc).
 980         // $fee_to_target_msat represents how much it costs to reach to this node from the payee,
 981         // meaning how much will be paid in fees after this node (to the best of our knowledge).
 982         // This data can later be helpful to optimize routing (pay lower fees).
 983         macro_rules! add_entries_to_cheapest_to_target_node {
 984                 ( $node: expr, $node_id: expr, $fee_to_target_msat: expr, $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr, $next_hops_path_penalty_msat: expr ) => {
 985                         let skip_node = if let Some(elem) = dist.get_mut(&$node_id) {
 986                                 let was_processed = elem.was_processed;
 987                                 elem.was_processed = true;
 988                                 was_processed
 989                         } else {
 990                                 // Entries are added to dist in add_entry!() when there is a channel from a node.
 991                                 // Because there are no channels from payee, it will not have a dist entry at this point.
 992                                 // If we're processing any other node, it is always be the result of a channel from it.
 993                                 assert_eq!($node_id, payee_node_id);
 994                                 false
 995                         };
 996
 997                         if !skip_node {
 998                                 if let Some(first_channels) = first_hop_targets.get(&$node_id) {
 999                                         for (ref first_hop, ref features, ref outbound_capacity_msat, _) in first_channels {
1000                                                 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);
1001                                         }
1002                                 }
1003
1004                                 let features = if let Some(node_info) = $node.announcement_info.as_ref() {
1005                                         &node_info.features
1006                                 } else {
1007                                         &empty_node_features
1008                                 };
1009
1010                                 if !features.requires_unknown_bits() {
1011                                         for chan_id in $node.channels.iter() {
1012                                                 let chan = network_channels.get(chan_id).unwrap();
1013                                                 if !chan.features.requires_unknown_bits() {
1014                                                         if chan.node_one == $node_id {
1015                                                                 // ie $node is one, ie next hop in A* is two, via the two_to_one channel
1016                                                                 if first_hops.is_none() || chan.node_two != our_node_id {
1017                                                                         if let Some(two_to_one) = chan.two_to_one.as_ref() {
1018                                                                                 if two_to_one.enabled {
1019                                                                                         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);
1020                                                                                 }
1021                                                                         }
1022                                                                 }
1023                                                         } else {
1024                                                                 if first_hops.is_none() || chan.node_one != our_node_id{
1025                                                                         if let Some(one_to_two) = chan.one_to_two.as_ref() {
1026                                                                                 if one_to_two.enabled {
1027                                                                                         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);
1028                                                                                 }
1029                                                                         }
1030                                                                 }
1031                                                         }
1032                                                 }
1033                                         }
1034                                 }
1035                         }
1036                 };
1037         }
1038
1039         let mut payment_paths = Vec::<PaymentPath>::new();
1040
1041         // TODO: diversify by nodes (so that all paths aren't doomed if one node is offline).
1042         'paths_collection: loop {
1043                 // For every new path, start from scratch, except
1044                 // bookkeeped_channels_liquidity_available_msat, which will improve
1045                 // the further iterations of path finding. Also don't erase first_hop_targets.
1046                 targets.clear();
1047                 dist.clear();
1048                 hit_minimum_limit = false;
1049
1050                 // If first hop is a private channel and the only way to reach the payee, this is the only
1051                 // place where it could be added.
1052                 if let Some(first_channels) = first_hop_targets.get(&payee_node_id) {
1053                         for (ref first_hop, ref features, ref outbound_capacity_msat, _) in first_channels {
1054                                 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);
1055                                 log_trace!(logger, "{} direct route to payee via SCID {}", if added { "Added" } else { "Skipped" }, first_hop);
1056                         }
1057                 }
1058
1059                 // Add the payee as a target, so that the payee-to-payer
1060                 // search algorithm knows what to start with.
1061                 match network_nodes.get(&payee_node_id) {
1062                         // The payee is not in our network graph, so nothing to add here.
1063                         // There is still a chance of reaching them via last_hops though,
1064                         // so don't yet fail the payment here.
1065                         // If not, targets.pop() will not even let us enter the loop in step 2.
1066                         None => {},
1067                         Some(node) => {
1068                                 add_entries_to_cheapest_to_target_node!(node, payee_node_id, 0, path_value_msat, 0, 0u64);
1069                         },
1070                 }
1071
1072                 // Step (2).
1073                 // If a caller provided us with last hops, add them to routing targets. Since this happens
1074                 // earlier than general path finding, they will be somewhat prioritized, although currently
1075                 // it matters only if the fees are exactly the same.
1076                 for route in payee.route_hints.iter().filter(|route| !route.0.is_empty()) {
1077                         let first_hop_in_route = &(route.0)[0];
1078                         let have_hop_src_in_graph =
1079                                 // Only add the hops in this route to our candidate set if either
1080                                 // we have a direct channel to the first hop or the first hop is
1081                                 // in the regular network graph.
1082                                 first_hop_targets.get(&NodeId::from_pubkey(&first_hop_in_route.src_node_id)).is_some() ||
1083                                 network_nodes.get(&NodeId::from_pubkey(&first_hop_in_route.src_node_id)).is_some();
1084                         if have_hop_src_in_graph {
1085                                 // We start building the path from reverse, i.e., from payee
1086                                 // to the first RouteHintHop in the path.
1087                                 let hop_iter = route.0.iter().rev();
1088                                 let prev_hop_iter = core::iter::once(&payee.pubkey).chain(
1089                                         route.0.iter().skip(1).rev().map(|hop| &hop.src_node_id));
1090                                 let mut hop_used = true;
1091                                 let mut aggregate_next_hops_fee_msat: u64 = 0;
1092                                 let mut aggregate_next_hops_path_htlc_minimum_msat: u64 = 0;
1093                                 let mut aggregate_next_hops_path_penalty_msat: u64 = 0;
1094
1095                                 for (idx, (hop, prev_hop_id)) in hop_iter.zip(prev_hop_iter).enumerate() {
1096                                         // BOLT 11 doesn't allow inclusion of features for the last hop hints, which
1097                                         // really sucks, cause we're gonna need that eventually.
1098                                         let hop_htlc_minimum_msat: u64 = hop.htlc_minimum_msat.unwrap_or(0);
1099
1100                                         let directional_info = DummyDirectionalChannelInfo {
1101                                                 cltv_expiry_delta: hop.cltv_expiry_delta as u32,
1102                                                 htlc_minimum_msat: hop_htlc_minimum_msat,
1103                                                 htlc_maximum_msat: hop.htlc_maximum_msat,
1104                                                 fees: hop.fees,
1105                                         };
1106
1107                                         let reqd_channel_cap = if let Some (val) = final_value_msat.checked_add(match idx {
1108                                                 0 => 999,
1109                                                 _ => aggregate_next_hops_fee_msat.checked_add(999).unwrap_or(u64::max_value())
1110                                         }) { Some( val / 1000 ) } else { break; }; // converting from msat or breaking if max ~ infinity
1111
1112                                         let src_node_id = NodeId::from_pubkey(&hop.src_node_id);
1113                                         let dest_node_id = NodeId::from_pubkey(&prev_hop_id);
1114                                         aggregate_next_hops_path_penalty_msat = aggregate_next_hops_path_penalty_msat
1115                                                 .checked_add(scorer.channel_penalty_msat(hop.short_channel_id, &src_node_id, &dest_node_id))
1116                                                 .unwrap_or_else(|| u64::max_value());
1117
1118                                         // We assume that the recipient only included route hints for routes which had
1119                                         // sufficient value to route `final_value_msat`. Note that in the case of "0-value"
1120                                         // invoices where the invoice does not specify value this may not be the case, but
1121                                         // better to include the hints than not.
1122                                         if !add_entry!(hop.short_channel_id, src_node_id, dest_node_id, directional_info, reqd_channel_cap, &empty_channel_features, aggregate_next_hops_fee_msat, path_value_msat, aggregate_next_hops_path_htlc_minimum_msat, aggregate_next_hops_path_penalty_msat) {
1123                                                 // If this hop was not used then there is no use checking the preceding hops
1124                                                 // in the RouteHint. We can break by just searching for a direct channel between
1125                                                 // last checked hop and first_hop_targets
1126                                                 hop_used = false;
1127                                         }
1128
1129                                         // Searching for a direct channel between last checked hop and first_hop_targets
1130                                         if let Some(first_channels) = first_hop_targets.get(&NodeId::from_pubkey(&prev_hop_id)) {
1131                                                 for (ref first_hop, ref features, ref outbound_capacity_msat, _) in first_channels {
1132                                                         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);
1133                                                 }
1134                                         }
1135
1136                                         if !hop_used {
1137                                                 break;
1138                                         }
1139
1140                                         // In the next values of the iterator, the aggregate fees already reflects
1141                                         // the sum of value sent from payer (final_value_msat) and routing fees
1142                                         // for the last node in the RouteHint. We need to just add the fees to
1143                                         // route through the current node so that the preceeding node (next iteration)
1144                                         // can use it.
1145                                         let hops_fee = compute_fees(aggregate_next_hops_fee_msat + final_value_msat, hop.fees)
1146                                                 .map_or(None, |inc| inc.checked_add(aggregate_next_hops_fee_msat));
1147                                         aggregate_next_hops_fee_msat = if let Some(val) = hops_fee { val } else { break; };
1148
1149                                         let hop_htlc_minimum_msat_inc = if let Some(val) = compute_fees(aggregate_next_hops_path_htlc_minimum_msat, hop.fees) { val } else { break; };
1150                                         let hops_path_htlc_minimum = aggregate_next_hops_path_htlc_minimum_msat
1151                                                 .checked_add(hop_htlc_minimum_msat_inc);
1152                                         aggregate_next_hops_path_htlc_minimum_msat = if let Some(val) = hops_path_htlc_minimum { cmp::max(hop_htlc_minimum_msat, val) } else { break; };
1153
1154                                         if idx == route.0.len() - 1 {
1155                                                 // The last hop in this iterator is the first hop in
1156                                                 // overall RouteHint.
1157                                                 // If this hop connects to a node with which we have a direct channel,
1158                                                 // ignore the network graph and, if the last hop was added, add our
1159                                                 // direct channel to the candidate set.
1160                                                 //
1161                                                 // Note that we *must* check if the last hop was added as `add_entry`
1162                                                 // always assumes that the third argument is a node to which we have a
1163                                                 // path.
1164                                                 if let Some(first_channels) = first_hop_targets.get(&NodeId::from_pubkey(&hop.src_node_id)) {
1165                                                         for (ref first_hop, ref features, ref outbound_capacity_msat, _) in first_channels {
1166                                                                 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);
1167                                                         }
1168                                                 }
1169                                         }
1170                                 }
1171                         }
1172                 }
1173
1174                 log_trace!(logger, "Starting main path collection loop with {} nodes pre-filled from first/last hops.", targets.len());
1175
1176                 // At this point, targets are filled with the data from first and
1177                 // last hops communicated by the caller, and the payment receiver.
1178                 let mut found_new_path = false;
1179
1180                 // Step (3).
1181                 // If this loop terminates due the exhaustion of targets, two situations are possible:
1182                 // - not enough outgoing liquidity:
1183                 //   0 < already_collected_value_msat < final_value_msat
1184                 // - enough outgoing liquidity:
1185                 //   final_value_msat <= already_collected_value_msat < recommended_value_msat
1186                 // Both these cases (and other cases except reaching recommended_value_msat) mean that
1187                 // paths_collection will be stopped because found_new_path==false.
1188                 // This is not necessarily a routing failure.
1189                 'path_construction: while let Some(RouteGraphNode { node_id, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat, path_penalty_msat, .. }) = targets.pop() {
1190
1191                         // Since we're going payee-to-payer, hitting our node as a target means we should stop
1192                         // traversing the graph and arrange the path out of what we found.
1193                         if node_id == our_node_id {
1194                                 let mut new_entry = dist.remove(&our_node_id).unwrap();
1195                                 let mut ordered_hops = vec!((new_entry.clone(), NodeFeatures::empty()));
1196
1197                                 'path_walk: loop {
1198                                         let mut features_set = false;
1199                                         if let Some(first_channels) = first_hop_targets.get(&ordered_hops.last().unwrap().0.node_id) {
1200                                                 for (scid, _, _, ref features) in first_channels {
1201                                                         if *scid == ordered_hops.last().unwrap().0.short_channel_id {
1202                                                                 ordered_hops.last_mut().unwrap().1 = features.clone();
1203                                                                 features_set = true;
1204                                                                 break;
1205                                                         }
1206                                                 }
1207                                         }
1208                                         if !features_set {
1209                                                 if let Some(node) = network_nodes.get(&ordered_hops.last().unwrap().0.node_id) {
1210                                                         if let Some(node_info) = node.announcement_info.as_ref() {
1211                                                                 ordered_hops.last_mut().unwrap().1 = node_info.features.clone();
1212                                                         } else {
1213                                                                 ordered_hops.last_mut().unwrap().1 = NodeFeatures::empty();
1214                                                         }
1215                                                 } else {
1216                                                         // We should be able to fill in features for everything except the last
1217                                                         // hop, if the last hop was provided via a BOLT 11 invoice (though we
1218                                                         // should be able to extend it further as BOLT 11 does have feature
1219                                                         // flags for the last hop node itself).
1220                                                         assert!(ordered_hops.last().unwrap().0.node_id == payee_node_id);
1221                                                 }
1222                                         }
1223
1224                                         // Means we succesfully traversed from the payer to the payee, now
1225                                         // save this path for the payment route. Also, update the liquidity
1226                                         // remaining on the used hops, so that we take them into account
1227                                         // while looking for more paths.
1228                                         if ordered_hops.last().unwrap().0.node_id == payee_node_id {
1229                                                 break 'path_walk;
1230                                         }
1231
1232                                         new_entry = match dist.remove(&ordered_hops.last().unwrap().0.node_id) {
1233                                                 Some(payment_hop) => payment_hop,
1234                                                 // We can't arrive at None because, if we ever add an entry to targets,
1235                                                 // we also fill in the entry in dist (see add_entry!).
1236                                                 None => unreachable!(),
1237                                         };
1238                                         // We "propagate" the fees one hop backward (topologically) here,
1239                                         // so that fees paid for a HTLC forwarding on the current channel are
1240                                         // associated with the previous channel (where they will be subtracted).
1241                                         ordered_hops.last_mut().unwrap().0.fee_msat = new_entry.hop_use_fee_msat;
1242                                         ordered_hops.last_mut().unwrap().0.cltv_expiry_delta = new_entry.cltv_expiry_delta;
1243                                         ordered_hops.push((new_entry.clone(), NodeFeatures::empty()));
1244                                 }
1245                                 ordered_hops.last_mut().unwrap().0.fee_msat = value_contribution_msat;
1246                                 ordered_hops.last_mut().unwrap().0.hop_use_fee_msat = 0;
1247                                 ordered_hops.last_mut().unwrap().0.cltv_expiry_delta = final_cltv_expiry_delta;
1248
1249                                 log_trace!(logger, "Found a path back to us from the target with {} hops contributing up to {} msat: {:?}",
1250                                         ordered_hops.len(), value_contribution_msat, ordered_hops);
1251
1252                                 let mut payment_path = PaymentPath {hops: ordered_hops};
1253
1254                                 // We could have possibly constructed a slightly inconsistent path: since we reduce
1255                                 // value being transferred along the way, we could have violated htlc_minimum_msat
1256                                 // on some channels we already passed (assuming dest->source direction). Here, we
1257                                 // recompute the fees again, so that if that's the case, we match the currently
1258                                 // underpaid htlc_minimum_msat with fees.
1259                                 payment_path.update_value_and_recompute_fees(cmp::min(value_contribution_msat, final_value_msat));
1260
1261                                 // Since a path allows to transfer as much value as
1262                                 // the smallest channel it has ("bottleneck"), we should recompute
1263                                 // the fees so sender HTLC don't overpay fees when traversing
1264                                 // larger channels than the bottleneck. This may happen because
1265                                 // when we were selecting those channels we were not aware how much value
1266                                 // this path will transfer, and the relative fee for them
1267                                 // might have been computed considering a larger value.
1268                                 // Remember that we used these channels so that we don't rely
1269                                 // on the same liquidity in future paths.
1270                                 let mut prevented_redundant_path_selection = false;
1271                                 for (payment_hop, _) in payment_path.hops.iter() {
1272                                         let channel_liquidity_available_msat = bookkeeped_channels_liquidity_available_msat.get_mut(&payment_hop.short_channel_id).unwrap();
1273                                         let mut spent_on_hop_msat = value_contribution_msat;
1274                                         let next_hops_fee_msat = payment_hop.next_hops_fee_msat;
1275                                         spent_on_hop_msat += next_hops_fee_msat;
1276                                         if spent_on_hop_msat == *channel_liquidity_available_msat {
1277                                                 // If this path used all of this channel's available liquidity, we know
1278                                                 // this path will not be selected again in the next loop iteration.
1279                                                 prevented_redundant_path_selection = true;
1280                                         }
1281                                         *channel_liquidity_available_msat -= spent_on_hop_msat;
1282                                 }
1283                                 if !prevented_redundant_path_selection {
1284                                         // If we weren't capped by hitting a liquidity limit on a channel in the path,
1285                                         // we'll probably end up picking the same path again on the next iteration.
1286                                         // Decrease the available liquidity of a hop in the middle of the path.
1287                                         let victim_scid = payment_path.hops[(payment_path.hops.len() - 1) / 2].0.short_channel_id;
1288                                         log_trace!(logger, "Disabling channel {} for future path building iterations to avoid duplicates.", victim_scid);
1289                                         let victim_liquidity = bookkeeped_channels_liquidity_available_msat.get_mut(&victim_scid).unwrap();
1290                                         *victim_liquidity = 0;
1291                                 }
1292
1293                                 // Track the total amount all our collected paths allow to send so that we:
1294                                 // - know when to stop looking for more paths
1295                                 // - know which of the hops are useless considering how much more sats we need
1296                                 //   (contributes_sufficient_value)
1297                                 already_collected_value_msat += value_contribution_msat;
1298
1299                                 payment_paths.push(payment_path);
1300                                 found_new_path = true;
1301                                 break 'path_construction;
1302                         }
1303
1304                         // If we found a path back to the payee, we shouldn't try to process it again. This is
1305                         // the equivalent of the `elem.was_processed` check in
1306                         // add_entries_to_cheapest_to_target_node!() (see comment there for more info).
1307                         if node_id == payee_node_id { continue 'path_construction; }
1308
1309                         // Otherwise, since the current target node is not us,
1310                         // keep "unrolling" the payment graph from payee to payer by
1311                         // finding a way to reach the current target from the payer side.
1312                         match network_nodes.get(&node_id) {
1313                                 None => {},
1314                                 Some(node) => {
1315                                         add_entries_to_cheapest_to_target_node!(node, node_id, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat, path_penalty_msat);
1316                                 },
1317                         }
1318                 }
1319
1320                 if !allow_mpp {
1321                         // If we don't support MPP, no use trying to gather more value ever.
1322                         break 'paths_collection;
1323                 }
1324
1325                 // Step (4).
1326                 // Stop either when the recommended value is reached or if no new path was found in this
1327                 // iteration.
1328                 // In the latter case, making another path finding attempt won't help,
1329                 // because we deterministically terminated the search due to low liquidity.
1330                 if already_collected_value_msat >= recommended_value_msat || !found_new_path {
1331                         log_trace!(logger, "Have now collected {} msat (seeking {} msat) in paths. Last path loop {} a new path.",
1332                                 already_collected_value_msat, recommended_value_msat, if found_new_path { "found" } else { "did not find" });
1333                         break 'paths_collection;
1334                 } else if found_new_path && already_collected_value_msat == final_value_msat && payment_paths.len() == 1 {
1335                         // Further, if this was our first walk of the graph, and we weren't limited by an
1336                         // htlc_minimum_msat, return immediately because this path should suffice. If we were
1337                         // limited by an htlc_minimum_msat value, find another path with a higher value,
1338                         // potentially allowing us to pay fees to meet the htlc_minimum on the new path while
1339                         // still keeping a lower total fee than this path.
1340                         if !hit_minimum_limit {
1341                                 log_trace!(logger, "Collected exactly our payment amount on the first pass, without hitting an htlc_minimum_msat limit, exiting.");
1342                                 break 'paths_collection;
1343                         }
1344                         log_trace!(logger, "Collected our payment amount on the first pass, but running again to collect extra paths with a potentially higher limit.");
1345                         path_value_msat = recommended_value_msat;
1346                 }
1347         }
1348
1349         // Step (5).
1350         if payment_paths.len() == 0 {
1351                 return Err(LightningError{err: "Failed to find a path to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1352         }
1353
1354         if already_collected_value_msat < final_value_msat {
1355                 return Err(LightningError{err: "Failed to find a sufficient route to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1356         }
1357
1358         // Sort by total fees and take the best paths.
1359         payment_paths.sort_by_key(|path| path.get_total_fee_paid_msat());
1360         if payment_paths.len() > 50 {
1361                 payment_paths.truncate(50);
1362         }
1363
1364         // Draw multiple sufficient routes by randomly combining the selected paths.
1365         let mut drawn_routes = Vec::new();
1366         for i in 0..payment_paths.len() {
1367                 let mut cur_route = Vec::<PaymentPath>::new();
1368                 let mut aggregate_route_value_msat = 0;
1369
1370                 // Step (6).
1371                 // TODO: real random shuffle
1372                 // Currently just starts with i_th and goes up to i-1_th in a looped way.
1373                 let cur_payment_paths = [&payment_paths[i..], &payment_paths[..i]].concat();
1374
1375                 // Step (7).
1376                 for payment_path in cur_payment_paths {
1377                         cur_route.push(payment_path.clone());
1378                         aggregate_route_value_msat += payment_path.get_value_msat();
1379                         if aggregate_route_value_msat > final_value_msat {
1380                                 // Last path likely overpaid. Substract it from the most expensive
1381                                 // (in terms of proportional fee) path in this route and recompute fees.
1382                                 // This might be not the most economically efficient way, but fewer paths
1383                                 // also makes routing more reliable.
1384                                 let mut overpaid_value_msat = aggregate_route_value_msat - final_value_msat;
1385
1386                                 // First, drop some expensive low-value paths entirely if possible.
1387                                 // Sort by value so that we drop many really-low values first, since
1388                                 // fewer paths is better: the payment is less likely to fail.
1389                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1390                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1391                                 cur_route.sort_by_key(|path| path.get_value_msat());
1392                                 // We should make sure that at least 1 path left.
1393                                 let mut paths_left = cur_route.len();
1394                                 cur_route.retain(|path| {
1395                                         if paths_left == 1 {
1396                                                 return true
1397                                         }
1398                                         let mut keep = true;
1399                                         let path_value_msat = path.get_value_msat();
1400                                         if path_value_msat <= overpaid_value_msat {
1401                                                 keep = false;
1402                                                 overpaid_value_msat -= path_value_msat;
1403                                                 paths_left -= 1;
1404                                         }
1405                                         keep
1406                                 });
1407
1408                                 if overpaid_value_msat == 0 {
1409                                         break;
1410                                 }
1411
1412                                 assert!(cur_route.len() > 0);
1413
1414                                 // Step (8).
1415                                 // Now, substract the overpaid value from the most-expensive path.
1416                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1417                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1418                                 cur_route.sort_by_key(|path| { path.hops.iter().map(|hop| hop.0.channel_fees.proportional_millionths as u64).sum::<u64>() });
1419                                 let expensive_payment_path = cur_route.first_mut().unwrap();
1420                                 // We already dropped all the small channels above, meaning all the
1421                                 // remaining channels are larger than remaining overpaid_value_msat.
1422                                 // Thus, this can't be negative.
1423                                 let expensive_path_new_value_msat = expensive_payment_path.get_value_msat() - overpaid_value_msat;
1424                                 expensive_payment_path.update_value_and_recompute_fees(expensive_path_new_value_msat);
1425                                 break;
1426                         }
1427                 }
1428                 drawn_routes.push(cur_route);
1429         }
1430
1431         // Step (9).
1432         // Select the best route by lowest total fee.
1433         drawn_routes.sort_by_key(|paths| paths.iter().map(|path| path.get_total_fee_paid_msat()).sum::<u64>());
1434         let mut selected_paths = Vec::<Vec<Result<RouteHop, LightningError>>>::new();
1435         for payment_path in drawn_routes.first().unwrap() {
1436                 selected_paths.push(payment_path.hops.iter().map(|(payment_hop, node_features)| {
1437                         Ok(RouteHop {
1438                                 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)})?,
1439                                 node_features: node_features.clone(),
1440                                 short_channel_id: payment_hop.short_channel_id,
1441                                 channel_features: payment_hop.channel_features.clone(),
1442                                 fee_msat: payment_hop.fee_msat,
1443                                 cltv_expiry_delta: payment_hop.cltv_expiry_delta,
1444                         })
1445                 }).collect());
1446         }
1447
1448         if let Some(features) = &payee.features {
1449                 for path in selected_paths.iter_mut() {
1450                         if let Ok(route_hop) = path.last_mut().unwrap() {
1451                                 route_hop.node_features = features.to_context();
1452                         }
1453                 }
1454         }
1455
1456         let route = Route {
1457                 paths: selected_paths.into_iter().map(|path| path.into_iter().collect()).collect::<Result<Vec<_>, _>>()?,
1458                 payee: Some(payee.clone()),
1459         };
1460         log_info!(logger, "Got route to {}: {}", payee.pubkey, log_route!(route));
1461         Ok(route)
1462 }
1463
1464 #[cfg(test)]
1465 mod tests {
1466         use routing;
1467         use routing::network_graph::{NetworkGraph, NetGraphMsgHandler, NodeId};
1468         use routing::router::{get_route, Payee, Route, RouteHint, RouteHintHop, RouteHop, RoutingFees};
1469         use routing::scorer::Scorer;
1470         use chain::transaction::OutPoint;
1471         use ln::features::{ChannelFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
1472         use ln::msgs::{ErrorAction, LightningError, OptionalField, UnsignedChannelAnnouncement, ChannelAnnouncement, RoutingMessageHandler,
1473            NodeAnnouncement, UnsignedNodeAnnouncement, ChannelUpdate, UnsignedChannelUpdate};
1474         use ln::channelmanager;
1475         use util::test_utils;
1476         use util::ser::Writeable;
1477
1478         use bitcoin::hashes::sha256d::Hash as Sha256dHash;
1479         use bitcoin::hashes::Hash;
1480         use bitcoin::network::constants::Network;
1481         use bitcoin::blockdata::constants::genesis_block;
1482         use bitcoin::blockdata::script::Builder;
1483         use bitcoin::blockdata::opcodes;
1484         use bitcoin::blockdata::transaction::TxOut;
1485
1486         use hex;
1487
1488         use bitcoin::secp256k1::key::{PublicKey,SecretKey};
1489         use bitcoin::secp256k1::{Secp256k1, All};
1490
1491         use prelude::*;
1492         use sync::{self, Arc};
1493
1494         fn get_channel_details(short_channel_id: Option<u64>, node_id: PublicKey,
1495                         features: InitFeatures, outbound_capacity_msat: u64) -> channelmanager::ChannelDetails {
1496                 channelmanager::ChannelDetails {
1497                         channel_id: [0; 32],
1498                         counterparty: channelmanager::ChannelCounterparty {
1499                                 features,
1500                                 node_id,
1501                                 unspendable_punishment_reserve: 0,
1502                                 forwarding_info: None,
1503                         },
1504                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
1505                         short_channel_id,
1506                         channel_value_satoshis: 0,
1507                         user_channel_id: 0,
1508                         outbound_capacity_msat,
1509                         inbound_capacity_msat: 42,
1510                         unspendable_punishment_reserve: None,
1511                         confirmations_required: None,
1512                         force_close_spend_delay: None,
1513                         is_outbound: true, is_funding_locked: true,
1514                         is_usable: true, is_public: true,
1515                 }
1516         }
1517
1518         // Using the same keys for LN and BTC ids
1519         fn add_channel(
1520                 net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>,
1521                 secp_ctx: &Secp256k1<All>, node_1_privkey: &SecretKey, node_2_privkey: &SecretKey, features: ChannelFeatures, short_channel_id: u64
1522         ) {
1523                 let node_id_1 = PublicKey::from_secret_key(&secp_ctx, node_1_privkey);
1524                 let node_id_2 = PublicKey::from_secret_key(&secp_ctx, node_2_privkey);
1525
1526                 let unsigned_announcement = UnsignedChannelAnnouncement {
1527                         features,
1528                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1529                         short_channel_id,
1530                         node_id_1,
1531                         node_id_2,
1532                         bitcoin_key_1: node_id_1,
1533                         bitcoin_key_2: node_id_2,
1534                         excess_data: Vec::new(),
1535                 };
1536
1537                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1538                 let valid_announcement = ChannelAnnouncement {
1539                         node_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1540                         node_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1541                         bitcoin_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1542                         bitcoin_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1543                         contents: unsigned_announcement.clone(),
1544                 };
1545                 match net_graph_msg_handler.handle_channel_announcement(&valid_announcement) {
1546                         Ok(res) => assert!(res),
1547                         _ => panic!()
1548                 };
1549         }
1550
1551         fn update_channel(
1552                 net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>,
1553                 secp_ctx: &Secp256k1<All>, node_privkey: &SecretKey, update: UnsignedChannelUpdate
1554         ) {
1555                 let msghash = hash_to_message!(&Sha256dHash::hash(&update.encode()[..])[..]);
1556                 let valid_channel_update = ChannelUpdate {
1557                         signature: secp_ctx.sign(&msghash, node_privkey),
1558                         contents: update.clone()
1559                 };
1560
1561                 match net_graph_msg_handler.handle_channel_update(&valid_channel_update) {
1562                         Ok(res) => assert!(res),
1563                         Err(_) => panic!()
1564                 };
1565         }
1566
1567         fn add_or_update_node(
1568                 net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>,
1569                 secp_ctx: &Secp256k1<All>, node_privkey: &SecretKey, features: NodeFeatures, timestamp: u32
1570         ) {
1571                 let node_id = PublicKey::from_secret_key(&secp_ctx, node_privkey);
1572                 let unsigned_announcement = UnsignedNodeAnnouncement {
1573                         features,
1574                         timestamp,
1575                         node_id,
1576                         rgb: [0; 3],
1577                         alias: [0; 32],
1578                         addresses: Vec::new(),
1579                         excess_address_data: Vec::new(),
1580                         excess_data: Vec::new(),
1581                 };
1582                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1583                 let valid_announcement = NodeAnnouncement {
1584                         signature: secp_ctx.sign(&msghash, node_privkey),
1585                         contents: unsigned_announcement.clone()
1586                 };
1587
1588                 match net_graph_msg_handler.handle_node_announcement(&valid_announcement) {
1589                         Ok(_) => (),
1590                         Err(_) => panic!()
1591                 };
1592         }
1593
1594         fn get_nodes(secp_ctx: &Secp256k1<All>) -> (SecretKey, PublicKey, Vec<SecretKey>, Vec<PublicKey>) {
1595                 let privkeys: Vec<SecretKey> = (2..10).map(|i| {
1596                         SecretKey::from_slice(&hex::decode(format!("{:02}", i).repeat(32)).unwrap()[..]).unwrap()
1597                 }).collect();
1598
1599                 let pubkeys = privkeys.iter().map(|secret| PublicKey::from_secret_key(&secp_ctx, secret)).collect();
1600
1601                 let our_privkey = SecretKey::from_slice(&hex::decode("01".repeat(32)).unwrap()[..]).unwrap();
1602                 let our_id = PublicKey::from_secret_key(&secp_ctx, &our_privkey);
1603
1604                 (our_privkey, our_id, privkeys, pubkeys)
1605         }
1606
1607         fn id_to_feature_flags(id: u8) -> Vec<u8> {
1608                 // Set the feature flags to the id'th odd (ie non-required) feature bit so that we can
1609                 // test for it later.
1610                 let idx = (id - 1) * 2 + 1;
1611                 if idx > 8*3 {
1612                         vec![1 << (idx - 8*3), 0, 0, 0]
1613                 } else if idx > 8*2 {
1614                         vec![1 << (idx - 8*2), 0, 0]
1615                 } else if idx > 8*1 {
1616                         vec![1 << (idx - 8*1), 0]
1617                 } else {
1618                         vec![1 << idx]
1619                 }
1620         }
1621
1622         fn build_graph() -> (Secp256k1<All>, NetGraphMsgHandler<sync::Arc<test_utils::TestChainSource>, sync::Arc<crate::util::test_utils::TestLogger>>, sync::Arc<test_utils::TestChainSource>, sync::Arc<test_utils::TestLogger>) {
1623                 let secp_ctx = Secp256k1::new();
1624                 let logger = Arc::new(test_utils::TestLogger::new());
1625                 let chain_monitor = Arc::new(test_utils::TestChainSource::new(Network::Testnet));
1626                 let network_graph = NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash());
1627                 let net_graph_msg_handler = NetGraphMsgHandler::new(network_graph, None, Arc::clone(&logger));
1628                 // Build network from our_id to node6:
1629                 //
1630                 //        -1(1)2-  node0  -1(3)2-
1631                 //       /                       \
1632                 // our_id -1(12)2- node7 -1(13)2--- node2
1633                 //       \                       /
1634                 //        -1(2)2-  node1  -1(4)2-
1635                 //
1636                 //
1637                 // chan1  1-to-2: disabled
1638                 // chan1  2-to-1: enabled, 0 fee
1639                 //
1640                 // chan2  1-to-2: enabled, ignored fee
1641                 // chan2  2-to-1: enabled, 0 fee
1642                 //
1643                 // chan3  1-to-2: enabled, 0 fee
1644                 // chan3  2-to-1: enabled, 100 msat fee
1645                 //
1646                 // chan4  1-to-2: enabled, 100% fee
1647                 // chan4  2-to-1: enabled, 0 fee
1648                 //
1649                 // chan12 1-to-2: enabled, ignored fee
1650                 // chan12 2-to-1: enabled, 0 fee
1651                 //
1652                 // chan13 1-to-2: enabled, 200% fee
1653                 // chan13 2-to-1: enabled, 0 fee
1654                 //
1655                 //
1656                 //       -1(5)2- node3 -1(8)2--
1657                 //       |         2          |
1658                 //       |       (11)         |
1659                 //      /          1           \
1660                 // node2--1(6)2- node4 -1(9)2--- node6 (not in global route map)
1661                 //      \                      /
1662                 //       -1(7)2- node5 -1(10)2-
1663                 //
1664                 // Channels 5, 8, 9 and 10 are private channels.
1665                 //
1666                 // chan5  1-to-2: enabled, 100 msat fee
1667                 // chan5  2-to-1: enabled, 0 fee
1668                 //
1669                 // chan6  1-to-2: enabled, 0 fee
1670                 // chan6  2-to-1: enabled, 0 fee
1671                 //
1672                 // chan7  1-to-2: enabled, 100% fee
1673                 // chan7  2-to-1: enabled, 0 fee
1674                 //
1675                 // chan8  1-to-2: enabled, variable fee (0 then 1000 msat)
1676                 // chan8  2-to-1: enabled, 0 fee
1677                 //
1678                 // chan9  1-to-2: enabled, 1001 msat fee
1679                 // chan9  2-to-1: enabled, 0 fee
1680                 //
1681                 // chan10 1-to-2: enabled, 0 fee
1682                 // chan10 2-to-1: enabled, 0 fee
1683                 //
1684                 // chan11 1-to-2: enabled, 0 fee
1685                 // chan11 2-to-1: enabled, 0 fee
1686
1687                 let (our_privkey, _, privkeys, _) = get_nodes(&secp_ctx);
1688
1689                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[0], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
1690                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1691                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1692                         short_channel_id: 1,
1693                         timestamp: 1,
1694                         flags: 1,
1695                         cltv_expiry_delta: 0,
1696                         htlc_minimum_msat: 0,
1697                         htlc_maximum_msat: OptionalField::Absent,
1698                         fee_base_msat: 0,
1699                         fee_proportional_millionths: 0,
1700                         excess_data: Vec::new()
1701                 });
1702
1703                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
1704
1705                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
1706                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1707                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1708                         short_channel_id: 2,
1709                         timestamp: 1,
1710                         flags: 0,
1711                         cltv_expiry_delta: u16::max_value(),
1712                         htlc_minimum_msat: 0,
1713                         htlc_maximum_msat: OptionalField::Absent,
1714                         fee_base_msat: u32::max_value(),
1715                         fee_proportional_millionths: u32::max_value(),
1716                         excess_data: Vec::new()
1717                 });
1718                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1719                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1720                         short_channel_id: 2,
1721                         timestamp: 1,
1722                         flags: 1,
1723                         cltv_expiry_delta: 0,
1724                         htlc_minimum_msat: 0,
1725                         htlc_maximum_msat: OptionalField::Absent,
1726                         fee_base_msat: 0,
1727                         fee_proportional_millionths: 0,
1728                         excess_data: Vec::new()
1729                 });
1730
1731                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
1732
1733                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[7], ChannelFeatures::from_le_bytes(id_to_feature_flags(12)), 12);
1734                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1735                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1736                         short_channel_id: 12,
1737                         timestamp: 1,
1738                         flags: 0,
1739                         cltv_expiry_delta: u16::max_value(),
1740                         htlc_minimum_msat: 0,
1741                         htlc_maximum_msat: OptionalField::Absent,
1742                         fee_base_msat: u32::max_value(),
1743                         fee_proportional_millionths: u32::max_value(),
1744                         excess_data: Vec::new()
1745                 });
1746                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1747                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1748                         short_channel_id: 12,
1749                         timestamp: 1,
1750                         flags: 1,
1751                         cltv_expiry_delta: 0,
1752                         htlc_minimum_msat: 0,
1753                         htlc_maximum_msat: OptionalField::Absent,
1754                         fee_base_msat: 0,
1755                         fee_proportional_millionths: 0,
1756                         excess_data: Vec::new()
1757                 });
1758
1759                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], NodeFeatures::from_le_bytes(id_to_feature_flags(8)), 0);
1760
1761                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
1762                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1763                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1764                         short_channel_id: 3,
1765                         timestamp: 1,
1766                         flags: 0,
1767                         cltv_expiry_delta: (3 << 8) | 1,
1768                         htlc_minimum_msat: 0,
1769                         htlc_maximum_msat: OptionalField::Absent,
1770                         fee_base_msat: 0,
1771                         fee_proportional_millionths: 0,
1772                         excess_data: Vec::new()
1773                 });
1774                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1775                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1776                         short_channel_id: 3,
1777                         timestamp: 1,
1778                         flags: 1,
1779                         cltv_expiry_delta: (3 << 8) | 2,
1780                         htlc_minimum_msat: 0,
1781                         htlc_maximum_msat: OptionalField::Absent,
1782                         fee_base_msat: 100,
1783                         fee_proportional_millionths: 0,
1784                         excess_data: Vec::new()
1785                 });
1786
1787                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
1788                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1789                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1790                         short_channel_id: 4,
1791                         timestamp: 1,
1792                         flags: 0,
1793                         cltv_expiry_delta: (4 << 8) | 1,
1794                         htlc_minimum_msat: 0,
1795                         htlc_maximum_msat: OptionalField::Absent,
1796                         fee_base_msat: 0,
1797                         fee_proportional_millionths: 1000000,
1798                         excess_data: Vec::new()
1799                 });
1800                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1801                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1802                         short_channel_id: 4,
1803                         timestamp: 1,
1804                         flags: 1,
1805                         cltv_expiry_delta: (4 << 8) | 2,
1806                         htlc_minimum_msat: 0,
1807                         htlc_maximum_msat: OptionalField::Absent,
1808                         fee_base_msat: 0,
1809                         fee_proportional_millionths: 0,
1810                         excess_data: Vec::new()
1811                 });
1812
1813                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(13)), 13);
1814                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1815                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1816                         short_channel_id: 13,
1817                         timestamp: 1,
1818                         flags: 0,
1819                         cltv_expiry_delta: (13 << 8) | 1,
1820                         htlc_minimum_msat: 0,
1821                         htlc_maximum_msat: OptionalField::Absent,
1822                         fee_base_msat: 0,
1823                         fee_proportional_millionths: 2000000,
1824                         excess_data: Vec::new()
1825                 });
1826                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1827                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1828                         short_channel_id: 13,
1829                         timestamp: 1,
1830                         flags: 1,
1831                         cltv_expiry_delta: (13 << 8) | 2,
1832                         htlc_minimum_msat: 0,
1833                         htlc_maximum_msat: OptionalField::Absent,
1834                         fee_base_msat: 0,
1835                         fee_proportional_millionths: 0,
1836                         excess_data: Vec::new()
1837                 });
1838
1839                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
1840
1841                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
1842                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1843                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1844                         short_channel_id: 6,
1845                         timestamp: 1,
1846                         flags: 0,
1847                         cltv_expiry_delta: (6 << 8) | 1,
1848                         htlc_minimum_msat: 0,
1849                         htlc_maximum_msat: OptionalField::Absent,
1850                         fee_base_msat: 0,
1851                         fee_proportional_millionths: 0,
1852                         excess_data: Vec::new()
1853                 });
1854                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1855                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1856                         short_channel_id: 6,
1857                         timestamp: 1,
1858                         flags: 1,
1859                         cltv_expiry_delta: (6 << 8) | 2,
1860                         htlc_minimum_msat: 0,
1861                         htlc_maximum_msat: OptionalField::Absent,
1862                         fee_base_msat: 0,
1863                         fee_proportional_millionths: 0,
1864                         excess_data: Vec::new(),
1865                 });
1866
1867                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(11)), 11);
1868                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1869                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1870                         short_channel_id: 11,
1871                         timestamp: 1,
1872                         flags: 0,
1873                         cltv_expiry_delta: (11 << 8) | 1,
1874                         htlc_minimum_msat: 0,
1875                         htlc_maximum_msat: OptionalField::Absent,
1876                         fee_base_msat: 0,
1877                         fee_proportional_millionths: 0,
1878                         excess_data: Vec::new()
1879                 });
1880                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
1881                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1882                         short_channel_id: 11,
1883                         timestamp: 1,
1884                         flags: 1,
1885                         cltv_expiry_delta: (11 << 8) | 2,
1886                         htlc_minimum_msat: 0,
1887                         htlc_maximum_msat: OptionalField::Absent,
1888                         fee_base_msat: 0,
1889                         fee_proportional_millionths: 0,
1890                         excess_data: Vec::new()
1891                 });
1892
1893                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(5)), 0);
1894
1895                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
1896
1897                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[5], ChannelFeatures::from_le_bytes(id_to_feature_flags(7)), 7);
1898                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1899                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1900                         short_channel_id: 7,
1901                         timestamp: 1,
1902                         flags: 0,
1903                         cltv_expiry_delta: (7 << 8) | 1,
1904                         htlc_minimum_msat: 0,
1905                         htlc_maximum_msat: OptionalField::Absent,
1906                         fee_base_msat: 0,
1907                         fee_proportional_millionths: 1000000,
1908                         excess_data: Vec::new()
1909                 });
1910                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[5], UnsignedChannelUpdate {
1911                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1912                         short_channel_id: 7,
1913                         timestamp: 1,
1914                         flags: 1,
1915                         cltv_expiry_delta: (7 << 8) | 2,
1916                         htlc_minimum_msat: 0,
1917                         htlc_maximum_msat: OptionalField::Absent,
1918                         fee_base_msat: 0,
1919                         fee_proportional_millionths: 0,
1920                         excess_data: Vec::new()
1921                 });
1922
1923                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[5], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
1924
1925                 (secp_ctx, net_graph_msg_handler, chain_monitor, logger)
1926         }
1927
1928         #[test]
1929         fn simple_route_test() {
1930                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1931                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1932                 let payee = Payee::new(nodes[2]);
1933                 let scorer = Scorer::new(0);
1934
1935                 // Simple route to 2 via 1
1936
1937                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 0, 42, Arc::clone(&logger), &scorer) {
1938                         assert_eq!(err, "Cannot send a payment of 0 msat");
1939                 } else { panic!(); }
1940
1941                 let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
1942                 assert_eq!(route.paths[0].len(), 2);
1943
1944                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
1945                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1946                 assert_eq!(route.paths[0][0].fee_msat, 100);
1947                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
1948                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
1949                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
1950
1951                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1952                 assert_eq!(route.paths[0][1].short_channel_id, 4);
1953                 assert_eq!(route.paths[0][1].fee_msat, 100);
1954                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1955                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1956                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
1957         }
1958
1959         #[test]
1960         fn invalid_first_hop_test() {
1961                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1962                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1963                 let payee = Payee::new(nodes[2]);
1964                 let scorer = Scorer::new(0);
1965
1966                 // Simple route to 2 via 1
1967
1968                 let our_chans = vec![get_channel_details(Some(2), our_id, InitFeatures::from_le_bytes(vec![0b11]), 100000)];
1969
1970                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 100, 42, Arc::clone(&logger), &scorer) {
1971                         assert_eq!(err, "First hop cannot have our_node_pubkey as a destination.");
1972                 } else { panic!(); }
1973
1974                 let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
1975                 assert_eq!(route.paths[0].len(), 2);
1976         }
1977
1978         #[test]
1979         fn htlc_minimum_test() {
1980                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1981                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1982                 let payee = Payee::new(nodes[2]);
1983                 let scorer = Scorer::new(0);
1984
1985                 // Simple route to 2 via 1
1986
1987                 // Disable other paths
1988                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1989                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1990                         short_channel_id: 12,
1991                         timestamp: 2,
1992                         flags: 2, // to disable
1993                         cltv_expiry_delta: 0,
1994                         htlc_minimum_msat: 0,
1995                         htlc_maximum_msat: OptionalField::Absent,
1996                         fee_base_msat: 0,
1997                         fee_proportional_millionths: 0,
1998                         excess_data: Vec::new()
1999                 });
2000                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2001                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2002                         short_channel_id: 3,
2003                         timestamp: 2,
2004                         flags: 2, // to disable
2005                         cltv_expiry_delta: 0,
2006                         htlc_minimum_msat: 0,
2007                         htlc_maximum_msat: OptionalField::Absent,
2008                         fee_base_msat: 0,
2009                         fee_proportional_millionths: 0,
2010                         excess_data: Vec::new()
2011                 });
2012                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2013                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2014                         short_channel_id: 13,
2015                         timestamp: 2,
2016                         flags: 2, // to disable
2017                         cltv_expiry_delta: 0,
2018                         htlc_minimum_msat: 0,
2019                         htlc_maximum_msat: OptionalField::Absent,
2020                         fee_base_msat: 0,
2021                         fee_proportional_millionths: 0,
2022                         excess_data: Vec::new()
2023                 });
2024                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2025                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2026                         short_channel_id: 6,
2027                         timestamp: 2,
2028                         flags: 2, // to disable
2029                         cltv_expiry_delta: 0,
2030                         htlc_minimum_msat: 0,
2031                         htlc_maximum_msat: OptionalField::Absent,
2032                         fee_base_msat: 0,
2033                         fee_proportional_millionths: 0,
2034                         excess_data: Vec::new()
2035                 });
2036                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2037                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2038                         short_channel_id: 7,
2039                         timestamp: 2,
2040                         flags: 2, // to disable
2041                         cltv_expiry_delta: 0,
2042                         htlc_minimum_msat: 0,
2043                         htlc_maximum_msat: OptionalField::Absent,
2044                         fee_base_msat: 0,
2045                         fee_proportional_millionths: 0,
2046                         excess_data: Vec::new()
2047                 });
2048
2049                 // Check against amount_to_transfer_over_msat.
2050                 // Set minimal HTLC of 200_000_000 msat.
2051                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2052                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2053                         short_channel_id: 2,
2054                         timestamp: 3,
2055                         flags: 0,
2056                         cltv_expiry_delta: 0,
2057                         htlc_minimum_msat: 200_000_000,
2058                         htlc_maximum_msat: OptionalField::Absent,
2059                         fee_base_msat: 0,
2060                         fee_proportional_millionths: 0,
2061                         excess_data: Vec::new()
2062                 });
2063
2064                 // Second hop only allows to forward 199_999_999 at most, thus not allowing the first hop to
2065                 // be used.
2066                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2067                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2068                         short_channel_id: 4,
2069                         timestamp: 3,
2070                         flags: 0,
2071                         cltv_expiry_delta: 0,
2072                         htlc_minimum_msat: 0,
2073                         htlc_maximum_msat: OptionalField::Present(199_999_999),
2074                         fee_base_msat: 0,
2075                         fee_proportional_millionths: 0,
2076                         excess_data: Vec::new()
2077                 });
2078
2079                 // Not possible to send 199_999_999, because the minimum on channel=2 is 200_000_000.
2080                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 199_999_999, 42, Arc::clone(&logger), &scorer) {
2081                         assert_eq!(err, "Failed to find a path to the given destination");
2082                 } else { panic!(); }
2083
2084                 // Lift the restriction on the first hop.
2085                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2086                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2087                         short_channel_id: 2,
2088                         timestamp: 4,
2089                         flags: 0,
2090                         cltv_expiry_delta: 0,
2091                         htlc_minimum_msat: 0,
2092                         htlc_maximum_msat: OptionalField::Absent,
2093                         fee_base_msat: 0,
2094                         fee_proportional_millionths: 0,
2095                         excess_data: Vec::new()
2096                 });
2097
2098                 // A payment above the minimum should pass
2099                 let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 199_999_999, 42, Arc::clone(&logger), &scorer).unwrap();
2100                 assert_eq!(route.paths[0].len(), 2);
2101         }
2102
2103         #[test]
2104         fn htlc_minimum_overpay_test() {
2105                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2106                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2107                 let payee = Payee::new(nodes[2]).with_features(InvoiceFeatures::known());
2108                 let scorer = Scorer::new(0);
2109
2110                 // A route to node#2 via two paths.
2111                 // One path allows transferring 35-40 sats, another one also allows 35-40 sats.
2112                 // Thus, they can't send 60 without overpaying.
2113                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2114                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2115                         short_channel_id: 2,
2116                         timestamp: 2,
2117                         flags: 0,
2118                         cltv_expiry_delta: 0,
2119                         htlc_minimum_msat: 35_000,
2120                         htlc_maximum_msat: OptionalField::Present(40_000),
2121                         fee_base_msat: 0,
2122                         fee_proportional_millionths: 0,
2123                         excess_data: Vec::new()
2124                 });
2125                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2126                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2127                         short_channel_id: 12,
2128                         timestamp: 3,
2129                         flags: 0,
2130                         cltv_expiry_delta: 0,
2131                         htlc_minimum_msat: 35_000,
2132                         htlc_maximum_msat: OptionalField::Present(40_000),
2133                         fee_base_msat: 0,
2134                         fee_proportional_millionths: 0,
2135                         excess_data: Vec::new()
2136                 });
2137
2138                 // Make 0 fee.
2139                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2140                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2141                         short_channel_id: 13,
2142                         timestamp: 2,
2143                         flags: 0,
2144                         cltv_expiry_delta: 0,
2145                         htlc_minimum_msat: 0,
2146                         htlc_maximum_msat: OptionalField::Absent,
2147                         fee_base_msat: 0,
2148                         fee_proportional_millionths: 0,
2149                         excess_data: Vec::new()
2150                 });
2151                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2152                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2153                         short_channel_id: 4,
2154                         timestamp: 2,
2155                         flags: 0,
2156                         cltv_expiry_delta: 0,
2157                         htlc_minimum_msat: 0,
2158                         htlc_maximum_msat: OptionalField::Absent,
2159                         fee_base_msat: 0,
2160                         fee_proportional_millionths: 0,
2161                         excess_data: Vec::new()
2162                 });
2163
2164                 // Disable other paths
2165                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2166                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2167                         short_channel_id: 1,
2168                         timestamp: 3,
2169                         flags: 2, // to disable
2170                         cltv_expiry_delta: 0,
2171                         htlc_minimum_msat: 0,
2172                         htlc_maximum_msat: OptionalField::Absent,
2173                         fee_base_msat: 0,
2174                         fee_proportional_millionths: 0,
2175                         excess_data: Vec::new()
2176                 });
2177
2178                 let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 60_000, 42, Arc::clone(&logger), &scorer).unwrap();
2179                 // Overpay fees to hit htlc_minimum_msat.
2180                 let overpaid_fees = route.paths[0][0].fee_msat + route.paths[1][0].fee_msat;
2181                 // TODO: this could be better balanced to overpay 10k and not 15k.
2182                 assert_eq!(overpaid_fees, 15_000);
2183
2184                 // Now, test that if there are 2 paths, a "cheaper" by fee path wouldn't be prioritized
2185                 // while taking even more fee to match htlc_minimum_msat.
2186                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2187                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2188                         short_channel_id: 12,
2189                         timestamp: 4,
2190                         flags: 0,
2191                         cltv_expiry_delta: 0,
2192                         htlc_minimum_msat: 65_000,
2193                         htlc_maximum_msat: OptionalField::Present(80_000),
2194                         fee_base_msat: 0,
2195                         fee_proportional_millionths: 0,
2196                         excess_data: Vec::new()
2197                 });
2198                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2199                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2200                         short_channel_id: 2,
2201                         timestamp: 3,
2202                         flags: 0,
2203                         cltv_expiry_delta: 0,
2204                         htlc_minimum_msat: 0,
2205                         htlc_maximum_msat: OptionalField::Absent,
2206                         fee_base_msat: 0,
2207                         fee_proportional_millionths: 0,
2208                         excess_data: Vec::new()
2209                 });
2210                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2211                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2212                         short_channel_id: 4,
2213                         timestamp: 4,
2214                         flags: 0,
2215                         cltv_expiry_delta: 0,
2216                         htlc_minimum_msat: 0,
2217                         htlc_maximum_msat: OptionalField::Absent,
2218                         fee_base_msat: 0,
2219                         fee_proportional_millionths: 100_000,
2220                         excess_data: Vec::new()
2221                 });
2222
2223                 let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 60_000, 42, Arc::clone(&logger), &scorer).unwrap();
2224                 // Fine to overpay for htlc_minimum_msat if it allows us to save fee.
2225                 assert_eq!(route.paths.len(), 1);
2226                 assert_eq!(route.paths[0][0].short_channel_id, 12);
2227                 let fees = route.paths[0][0].fee_msat;
2228                 assert_eq!(fees, 5_000);
2229
2230                 let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 50_000, 42, Arc::clone(&logger), &scorer).unwrap();
2231                 // Not fine to overpay for htlc_minimum_msat if it requires paying more than fee on
2232                 // the other channel.
2233                 assert_eq!(route.paths.len(), 1);
2234                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2235                 let fees = route.paths[0][0].fee_msat;
2236                 assert_eq!(fees, 5_000);
2237         }
2238
2239         #[test]
2240         fn disable_channels_test() {
2241                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2242                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2243                 let payee = Payee::new(nodes[2]);
2244                 let scorer = Scorer::new(0);
2245
2246                 // // Disable channels 4 and 12 by flags=2
2247                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2248                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2249                         short_channel_id: 4,
2250                         timestamp: 2,
2251                         flags: 2, // to disable
2252                         cltv_expiry_delta: 0,
2253                         htlc_minimum_msat: 0,
2254                         htlc_maximum_msat: OptionalField::Absent,
2255                         fee_base_msat: 0,
2256                         fee_proportional_millionths: 0,
2257                         excess_data: Vec::new()
2258                 });
2259                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2260                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2261                         short_channel_id: 12,
2262                         timestamp: 2,
2263                         flags: 2, // to disable
2264                         cltv_expiry_delta: 0,
2265                         htlc_minimum_msat: 0,
2266                         htlc_maximum_msat: OptionalField::Absent,
2267                         fee_base_msat: 0,
2268                         fee_proportional_millionths: 0,
2269                         excess_data: Vec::new()
2270                 });
2271
2272                 // If all the channels require some features we don't understand, route should fail
2273                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 100, 42, Arc::clone(&logger), &scorer) {
2274                         assert_eq!(err, "Failed to find a path to the given destination");
2275                 } else { panic!(); }
2276
2277                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2278                 let our_chans = vec![get_channel_details(Some(42), nodes[7].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2279                 let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 100, 42, Arc::clone(&logger), &scorer).unwrap();
2280                 assert_eq!(route.paths[0].len(), 2);
2281
2282                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2283                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2284                 assert_eq!(route.paths[0][0].fee_msat, 200);
2285                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2286                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
2287                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2288
2289                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2290                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2291                 assert_eq!(route.paths[0][1].fee_msat, 100);
2292                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2293                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2294                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2295         }
2296
2297         #[test]
2298         fn disable_node_test() {
2299                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2300                 let (_, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2301                 let payee = Payee::new(nodes[2]);
2302                 let scorer = Scorer::new(0);
2303
2304                 // Disable nodes 1, 2, and 8 by requiring unknown feature bits
2305                 let unknown_features = NodeFeatures::known().set_unknown_feature_required();
2306                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], unknown_features.clone(), 1);
2307                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], unknown_features.clone(), 1);
2308                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], unknown_features.clone(), 1);
2309
2310                 // If all nodes require some features we don't understand, route should fail
2311                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 100, 42, Arc::clone(&logger), &scorer) {
2312                         assert_eq!(err, "Failed to find a path to the given destination");
2313                 } else { panic!(); }
2314
2315                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2316                 let our_chans = vec![get_channel_details(Some(42), nodes[7].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2317                 let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 100, 42, Arc::clone(&logger), &scorer).unwrap();
2318                 assert_eq!(route.paths[0].len(), 2);
2319
2320                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2321                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2322                 assert_eq!(route.paths[0][0].fee_msat, 200);
2323                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2324                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
2325                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2326
2327                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2328                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2329                 assert_eq!(route.paths[0][1].fee_msat, 100);
2330                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2331                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2332                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2333
2334                 // Note that we don't test disabling node 3 and failing to route to it, as we (somewhat
2335                 // naively) assume that the user checked the feature bits on the invoice, which override
2336                 // the node_announcement.
2337         }
2338
2339         #[test]
2340         fn our_chans_test() {
2341                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2342                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2343                 let scorer = Scorer::new(0);
2344
2345                 // Route to 1 via 2 and 3 because our channel to 1 is disabled
2346                 let payee = Payee::new(nodes[0]);
2347                 let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
2348                 assert_eq!(route.paths[0].len(), 3);
2349
2350                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2351                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2352                 assert_eq!(route.paths[0][0].fee_msat, 200);
2353                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2354                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2355                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2356
2357                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2358                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2359                 assert_eq!(route.paths[0][1].fee_msat, 100);
2360                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (3 << 8) | 2);
2361                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2362                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2363
2364                 assert_eq!(route.paths[0][2].pubkey, nodes[0]);
2365                 assert_eq!(route.paths[0][2].short_channel_id, 3);
2366                 assert_eq!(route.paths[0][2].fee_msat, 100);
2367                 assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
2368                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(1));
2369                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(3));
2370
2371                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2372                 let payee = Payee::new(nodes[2]);
2373                 let our_chans = vec![get_channel_details(Some(42), nodes[7].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2374                 let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 100, 42, Arc::clone(&logger), &scorer).unwrap();
2375                 assert_eq!(route.paths[0].len(), 2);
2376
2377                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2378                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2379                 assert_eq!(route.paths[0][0].fee_msat, 200);
2380                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2381                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2382                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2383
2384                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2385                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2386                 assert_eq!(route.paths[0][1].fee_msat, 100);
2387                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2388                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2389                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2390         }
2391
2392         fn last_hops(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2393                 let zero_fees = RoutingFees {
2394                         base_msat: 0,
2395                         proportional_millionths: 0,
2396                 };
2397                 vec![RouteHint(vec![RouteHintHop {
2398                         src_node_id: nodes[3],
2399                         short_channel_id: 8,
2400                         fees: zero_fees,
2401                         cltv_expiry_delta: (8 << 8) | 1,
2402                         htlc_minimum_msat: None,
2403                         htlc_maximum_msat: None,
2404                 }
2405                 ]), RouteHint(vec![RouteHintHop {
2406                         src_node_id: nodes[4],
2407                         short_channel_id: 9,
2408                         fees: RoutingFees {
2409                                 base_msat: 1001,
2410                                 proportional_millionths: 0,
2411                         },
2412                         cltv_expiry_delta: (9 << 8) | 1,
2413                         htlc_minimum_msat: None,
2414                         htlc_maximum_msat: None,
2415                 }]), RouteHint(vec![RouteHintHop {
2416                         src_node_id: nodes[5],
2417                         short_channel_id: 10,
2418                         fees: zero_fees,
2419                         cltv_expiry_delta: (10 << 8) | 1,
2420                         htlc_minimum_msat: None,
2421                         htlc_maximum_msat: None,
2422                 }])]
2423         }
2424
2425         fn last_hops_multi_private_channels(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2426                 let zero_fees = RoutingFees {
2427                         base_msat: 0,
2428                         proportional_millionths: 0,
2429                 };
2430                 vec![RouteHint(vec![RouteHintHop {
2431                         src_node_id: nodes[2],
2432                         short_channel_id: 5,
2433                         fees: RoutingFees {
2434                                 base_msat: 100,
2435                                 proportional_millionths: 0,
2436                         },
2437                         cltv_expiry_delta: (5 << 8) | 1,
2438                         htlc_minimum_msat: None,
2439                         htlc_maximum_msat: None,
2440                 }, RouteHintHop {
2441                         src_node_id: nodes[3],
2442                         short_channel_id: 8,
2443                         fees: zero_fees,
2444                         cltv_expiry_delta: (8 << 8) | 1,
2445                         htlc_minimum_msat: None,
2446                         htlc_maximum_msat: None,
2447                 }
2448                 ]), RouteHint(vec![RouteHintHop {
2449                         src_node_id: nodes[4],
2450                         short_channel_id: 9,
2451                         fees: RoutingFees {
2452                                 base_msat: 1001,
2453                                 proportional_millionths: 0,
2454                         },
2455                         cltv_expiry_delta: (9 << 8) | 1,
2456                         htlc_minimum_msat: None,
2457                         htlc_maximum_msat: None,
2458                 }]), RouteHint(vec![RouteHintHop {
2459                         src_node_id: nodes[5],
2460                         short_channel_id: 10,
2461                         fees: zero_fees,
2462                         cltv_expiry_delta: (10 << 8) | 1,
2463                         htlc_minimum_msat: None,
2464                         htlc_maximum_msat: None,
2465                 }])]
2466         }
2467
2468         #[test]
2469         fn partial_route_hint_test() {
2470                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2471                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2472                 let scorer = Scorer::new(0);
2473
2474                 // Simple test across 2, 3, 5, and 4 via a last_hop channel
2475                 // Tests the behaviour when the RouteHint contains a suboptimal hop.
2476                 // RouteHint may be partially used by the algo to build the best path.
2477
2478                 // First check that last hop can't have its source as the payee.
2479                 let invalid_last_hop = RouteHint(vec![RouteHintHop {
2480                         src_node_id: nodes[6],
2481                         short_channel_id: 8,
2482                         fees: RoutingFees {
2483                                 base_msat: 1000,
2484                                 proportional_millionths: 0,
2485                         },
2486                         cltv_expiry_delta: (8 << 8) | 1,
2487                         htlc_minimum_msat: None,
2488                         htlc_maximum_msat: None,
2489                 }]);
2490
2491                 let mut invalid_last_hops = last_hops_multi_private_channels(&nodes);
2492                 invalid_last_hops.push(invalid_last_hop);
2493                 {
2494                         let payee = Payee::new(nodes[6]).with_route_hints(invalid_last_hops);
2495                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 100, 42, Arc::clone(&logger), &scorer) {
2496                                 assert_eq!(err, "Route hint cannot have the payee as the source.");
2497                         } else { panic!(); }
2498                 }
2499
2500                 let payee = Payee::new(nodes[6]).with_route_hints(last_hops_multi_private_channels(&nodes));
2501                 let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
2502                 assert_eq!(route.paths[0].len(), 5);
2503
2504                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2505                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2506                 assert_eq!(route.paths[0][0].fee_msat, 100);
2507                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2508                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2509                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2510
2511                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2512                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2513                 assert_eq!(route.paths[0][1].fee_msat, 0);
2514                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2515                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2516                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2517
2518                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2519                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2520                 assert_eq!(route.paths[0][2].fee_msat, 0);
2521                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2522                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2523                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2524
2525                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2526                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2527                 assert_eq!(route.paths[0][3].fee_msat, 0);
2528                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2529                 // If we have a peer in the node map, we'll use their features here since we don't have
2530                 // a way of figuring out their features from the invoice:
2531                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2532                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2533
2534                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2535                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2536                 assert_eq!(route.paths[0][4].fee_msat, 100);
2537                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2538                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2539                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2540         }
2541
2542         fn empty_last_hop(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2543                 let zero_fees = RoutingFees {
2544                         base_msat: 0,
2545                         proportional_millionths: 0,
2546                 };
2547                 vec![RouteHint(vec![RouteHintHop {
2548                         src_node_id: nodes[3],
2549                         short_channel_id: 8,
2550                         fees: zero_fees,
2551                         cltv_expiry_delta: (8 << 8) | 1,
2552                         htlc_minimum_msat: None,
2553                         htlc_maximum_msat: None,
2554                 }]), RouteHint(vec![
2555
2556                 ]), RouteHint(vec![RouteHintHop {
2557                         src_node_id: nodes[5],
2558                         short_channel_id: 10,
2559                         fees: zero_fees,
2560                         cltv_expiry_delta: (10 << 8) | 1,
2561                         htlc_minimum_msat: None,
2562                         htlc_maximum_msat: None,
2563                 }])]
2564         }
2565
2566         #[test]
2567         fn ignores_empty_last_hops_test() {
2568                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2569                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2570                 let payee = Payee::new(nodes[6]).with_route_hints(empty_last_hop(&nodes));
2571                 let scorer = Scorer::new(0);
2572
2573                 // Test handling of an empty RouteHint passed in Invoice.
2574
2575                 let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
2576                 assert_eq!(route.paths[0].len(), 5);
2577
2578                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2579                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2580                 assert_eq!(route.paths[0][0].fee_msat, 100);
2581                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2582                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2583                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2584
2585                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2586                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2587                 assert_eq!(route.paths[0][1].fee_msat, 0);
2588                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2589                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2590                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2591
2592                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2593                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2594                 assert_eq!(route.paths[0][2].fee_msat, 0);
2595                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2596                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2597                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2598
2599                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2600                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2601                 assert_eq!(route.paths[0][3].fee_msat, 0);
2602                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2603                 // If we have a peer in the node map, we'll use their features here since we don't have
2604                 // a way of figuring out their features from the invoice:
2605                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2606                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2607
2608                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2609                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2610                 assert_eq!(route.paths[0][4].fee_msat, 100);
2611                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2612                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2613                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2614         }
2615
2616         fn multi_hint_last_hops(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2617                 let zero_fees = RoutingFees {
2618                         base_msat: 0,
2619                         proportional_millionths: 0,
2620                 };
2621                 vec![RouteHint(vec![RouteHintHop {
2622                         src_node_id: nodes[2],
2623                         short_channel_id: 5,
2624                         fees: RoutingFees {
2625                                 base_msat: 100,
2626                                 proportional_millionths: 0,
2627                         },
2628                         cltv_expiry_delta: (5 << 8) | 1,
2629                         htlc_minimum_msat: None,
2630                         htlc_maximum_msat: None,
2631                 }, RouteHintHop {
2632                         src_node_id: nodes[3],
2633                         short_channel_id: 8,
2634                         fees: zero_fees,
2635                         cltv_expiry_delta: (8 << 8) | 1,
2636                         htlc_minimum_msat: None,
2637                         htlc_maximum_msat: None,
2638                 }]), RouteHint(vec![RouteHintHop {
2639                         src_node_id: nodes[5],
2640                         short_channel_id: 10,
2641                         fees: zero_fees,
2642                         cltv_expiry_delta: (10 << 8) | 1,
2643                         htlc_minimum_msat: None,
2644                         htlc_maximum_msat: None,
2645                 }])]
2646         }
2647
2648         #[test]
2649         fn multi_hint_last_hops_test() {
2650                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2651                 let (_, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2652                 let payee = Payee::new(nodes[6]).with_route_hints(multi_hint_last_hops(&nodes));
2653                 let scorer = Scorer::new(0);
2654                 // Test through channels 2, 3, 5, 8.
2655                 // Test shows that multiple hop hints are considered.
2656
2657                 // Disabling channels 6 & 7 by flags=2
2658                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2659                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2660                         short_channel_id: 6,
2661                         timestamp: 2,
2662                         flags: 2, // to disable
2663                         cltv_expiry_delta: 0,
2664                         htlc_minimum_msat: 0,
2665                         htlc_maximum_msat: OptionalField::Absent,
2666                         fee_base_msat: 0,
2667                         fee_proportional_millionths: 0,
2668                         excess_data: Vec::new()
2669                 });
2670                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2671                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2672                         short_channel_id: 7,
2673                         timestamp: 2,
2674                         flags: 2, // to disable
2675                         cltv_expiry_delta: 0,
2676                         htlc_minimum_msat: 0,
2677                         htlc_maximum_msat: OptionalField::Absent,
2678                         fee_base_msat: 0,
2679                         fee_proportional_millionths: 0,
2680                         excess_data: Vec::new()
2681                 });
2682
2683                 let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
2684                 assert_eq!(route.paths[0].len(), 4);
2685
2686                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2687                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2688                 assert_eq!(route.paths[0][0].fee_msat, 200);
2689                 assert_eq!(route.paths[0][0].cltv_expiry_delta, 1025);
2690                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2691                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2692
2693                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2694                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2695                 assert_eq!(route.paths[0][1].fee_msat, 100);
2696                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 1281);
2697                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2698                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2699
2700                 assert_eq!(route.paths[0][2].pubkey, nodes[3]);
2701                 assert_eq!(route.paths[0][2].short_channel_id, 5);
2702                 assert_eq!(route.paths[0][2].fee_msat, 0);
2703                 assert_eq!(route.paths[0][2].cltv_expiry_delta, 2049);
2704                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(4));
2705                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &Vec::<u8>::new());
2706
2707                 assert_eq!(route.paths[0][3].pubkey, nodes[6]);
2708                 assert_eq!(route.paths[0][3].short_channel_id, 8);
2709                 assert_eq!(route.paths[0][3].fee_msat, 100);
2710                 assert_eq!(route.paths[0][3].cltv_expiry_delta, 42);
2711                 assert_eq!(route.paths[0][3].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2712                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2713         }
2714
2715         fn last_hops_with_public_channel(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2716                 let zero_fees = RoutingFees {
2717                         base_msat: 0,
2718                         proportional_millionths: 0,
2719                 };
2720                 vec![RouteHint(vec![RouteHintHop {
2721                         src_node_id: nodes[4],
2722                         short_channel_id: 11,
2723                         fees: zero_fees,
2724                         cltv_expiry_delta: (11 << 8) | 1,
2725                         htlc_minimum_msat: None,
2726                         htlc_maximum_msat: None,
2727                 }, RouteHintHop {
2728                         src_node_id: nodes[3],
2729                         short_channel_id: 8,
2730                         fees: zero_fees,
2731                         cltv_expiry_delta: (8 << 8) | 1,
2732                         htlc_minimum_msat: None,
2733                         htlc_maximum_msat: None,
2734                 }]), RouteHint(vec![RouteHintHop {
2735                         src_node_id: nodes[4],
2736                         short_channel_id: 9,
2737                         fees: RoutingFees {
2738                                 base_msat: 1001,
2739                                 proportional_millionths: 0,
2740                         },
2741                         cltv_expiry_delta: (9 << 8) | 1,
2742                         htlc_minimum_msat: None,
2743                         htlc_maximum_msat: None,
2744                 }]), RouteHint(vec![RouteHintHop {
2745                         src_node_id: nodes[5],
2746                         short_channel_id: 10,
2747                         fees: zero_fees,
2748                         cltv_expiry_delta: (10 << 8) | 1,
2749                         htlc_minimum_msat: None,
2750                         htlc_maximum_msat: None,
2751                 }])]
2752         }
2753
2754         #[test]
2755         fn last_hops_with_public_channel_test() {
2756                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2757                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2758                 let payee = Payee::new(nodes[6]).with_route_hints(last_hops_with_public_channel(&nodes));
2759                 let scorer = Scorer::new(0);
2760                 // This test shows that public routes can be present in the invoice
2761                 // which would be handled in the same manner.
2762
2763                 let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
2764                 assert_eq!(route.paths[0].len(), 5);
2765
2766                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2767                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2768                 assert_eq!(route.paths[0][0].fee_msat, 100);
2769                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2770                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2771                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2772
2773                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2774                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2775                 assert_eq!(route.paths[0][1].fee_msat, 0);
2776                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2777                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2778                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2779
2780                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2781                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2782                 assert_eq!(route.paths[0][2].fee_msat, 0);
2783                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2784                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2785                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2786
2787                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2788                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2789                 assert_eq!(route.paths[0][3].fee_msat, 0);
2790                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2791                 // If we have a peer in the node map, we'll use their features here since we don't have
2792                 // a way of figuring out their features from the invoice:
2793                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2794                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new());
2795
2796                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2797                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2798                 assert_eq!(route.paths[0][4].fee_msat, 100);
2799                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2800                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2801                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2802         }
2803
2804         #[test]
2805         fn our_chans_last_hop_connect_test() {
2806                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2807                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2808                 let scorer = Scorer::new(0);
2809
2810                 // Simple test with outbound channel to 4 to test that last_hops and first_hops connect
2811                 let our_chans = vec![get_channel_details(Some(42), nodes[3].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2812                 let mut last_hops = last_hops(&nodes);
2813                 let payee = Payee::new(nodes[6]).with_route_hints(last_hops.clone());
2814                 let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 100, 42, Arc::clone(&logger), &scorer).unwrap();
2815                 assert_eq!(route.paths[0].len(), 2);
2816
2817                 assert_eq!(route.paths[0][0].pubkey, nodes[3]);
2818                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2819                 assert_eq!(route.paths[0][0].fee_msat, 0);
2820                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2821                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2822                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2823
2824                 assert_eq!(route.paths[0][1].pubkey, nodes[6]);
2825                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2826                 assert_eq!(route.paths[0][1].fee_msat, 100);
2827                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2828                 assert_eq!(route.paths[0][1].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2829                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2830
2831                 last_hops[0].0[0].fees.base_msat = 1000;
2832
2833                 // Revert to via 6 as the fee on 8 goes up
2834                 let payee = Payee::new(nodes[6]).with_route_hints(last_hops);
2835                 let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 100, 42, Arc::clone(&logger), &scorer).unwrap();
2836                 assert_eq!(route.paths[0].len(), 4);
2837
2838                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2839                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2840                 assert_eq!(route.paths[0][0].fee_msat, 200); // fee increased as its % of value transferred across node
2841                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2842                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2843                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2844
2845                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2846                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2847                 assert_eq!(route.paths[0][1].fee_msat, 100);
2848                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (7 << 8) | 1);
2849                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2850                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2851
2852                 assert_eq!(route.paths[0][2].pubkey, nodes[5]);
2853                 assert_eq!(route.paths[0][2].short_channel_id, 7);
2854                 assert_eq!(route.paths[0][2].fee_msat, 0);
2855                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (10 << 8) | 1);
2856                 // If we have a peer in the node map, we'll use their features here since we don't have
2857                 // a way of figuring out their features from the invoice:
2858                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
2859                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(7));
2860
2861                 assert_eq!(route.paths[0][3].pubkey, nodes[6]);
2862                 assert_eq!(route.paths[0][3].short_channel_id, 10);
2863                 assert_eq!(route.paths[0][3].fee_msat, 100);
2864                 assert_eq!(route.paths[0][3].cltv_expiry_delta, 42);
2865                 assert_eq!(route.paths[0][3].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2866                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2867
2868                 // ...but still use 8 for larger payments as 6 has a variable feerate
2869                 let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 2000, 42, Arc::clone(&logger), &scorer).unwrap();
2870                 assert_eq!(route.paths[0].len(), 5);
2871
2872                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2873                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2874                 assert_eq!(route.paths[0][0].fee_msat, 3000);
2875                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2876                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2877                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2878
2879                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2880                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2881                 assert_eq!(route.paths[0][1].fee_msat, 0);
2882                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2883                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2884                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2885
2886                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2887                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2888                 assert_eq!(route.paths[0][2].fee_msat, 0);
2889                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2890                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2891                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2892
2893                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2894                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2895                 assert_eq!(route.paths[0][3].fee_msat, 1000);
2896                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2897                 // If we have a peer in the node map, we'll use their features here since we don't have
2898                 // a way of figuring out their features from the invoice:
2899                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2900                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2901
2902                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2903                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2904                 assert_eq!(route.paths[0][4].fee_msat, 2000);
2905                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2906                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2907                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2908         }
2909
2910         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> {
2911                 let source_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 41).repeat(32)).unwrap()[..]).unwrap());
2912                 let middle_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 42).repeat(32)).unwrap()[..]).unwrap());
2913                 let target_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 43).repeat(32)).unwrap()[..]).unwrap());
2914
2915                 // If we specify a channel to a middle hop, that overrides our local channel view and that gets used
2916                 let last_hops = RouteHint(vec![RouteHintHop {
2917                         src_node_id: middle_node_id,
2918                         short_channel_id: 8,
2919                         fees: RoutingFees {
2920                                 base_msat: 1000,
2921                                 proportional_millionths: last_hop_fee_prop,
2922                         },
2923                         cltv_expiry_delta: (8 << 8) | 1,
2924                         htlc_minimum_msat: None,
2925                         htlc_maximum_msat: last_hop_htlc_max,
2926                 }]);
2927                 let payee = Payee::new(target_node_id).with_route_hints(vec![last_hops]);
2928                 let our_chans = vec![get_channel_details(Some(42), middle_node_id, InitFeatures::from_le_bytes(vec![0b11]), outbound_capacity_msat)];
2929                 let scorer = Scorer::new(0);
2930                 get_route(&source_node_id, &payee, &NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash()), Some(&our_chans.iter().collect::<Vec<_>>()), route_val, 42, &test_utils::TestLogger::new(), &scorer)
2931         }
2932
2933         #[test]
2934         fn unannounced_path_test() {
2935                 // We should be able to send a payment to a destination without any help of a routing graph
2936                 // if we have a channel with a common counterparty that appears in the first and last hop
2937                 // hints.
2938                 let route = do_unannounced_path_test(None, 1, 2000000, 1000000).unwrap();
2939
2940                 let middle_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 42).repeat(32)).unwrap()[..]).unwrap());
2941                 let target_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 43).repeat(32)).unwrap()[..]).unwrap());
2942                 assert_eq!(route.paths[0].len(), 2);
2943
2944                 assert_eq!(route.paths[0][0].pubkey, middle_node_id);
2945                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2946                 assert_eq!(route.paths[0][0].fee_msat, 1001);
2947                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2948                 assert_eq!(route.paths[0][0].node_features.le_flags(), &[0b11]);
2949                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2950
2951                 assert_eq!(route.paths[0][1].pubkey, target_node_id);
2952                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2953                 assert_eq!(route.paths[0][1].fee_msat, 1000000);
2954                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2955                 assert_eq!(route.paths[0][1].node_features.le_flags(), &[0; 0]); // We dont pass flags in from invoices yet
2956                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2957         }
2958
2959         #[test]
2960         fn overflow_unannounced_path_test_liquidity_underflow() {
2961                 // Previously, when we had a last-hop hint connected directly to a first-hop channel, where
2962                 // the last-hop had a fee which overflowed a u64, we'd panic.
2963                 // This was due to us adding the first-hop from us unconditionally, causing us to think
2964                 // we'd built a path (as our node is in the "best candidate" set), when we had not.
2965                 // In this test, we previously hit a subtraction underflow due to having less available
2966                 // liquidity at the last hop than 0.
2967                 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());
2968         }
2969
2970         #[test]
2971         fn overflow_unannounced_path_test_feerate_overflow() {
2972                 // This tests for the same case as above, except instead of hitting a subtraction
2973                 // underflow, we hit a case where the fee charged at a hop overflowed.
2974                 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());
2975         }
2976
2977         #[test]
2978         fn available_amount_while_routing_test() {
2979                 // Tests whether we choose the correct available channel amount while routing.
2980
2981                 let (secp_ctx, mut net_graph_msg_handler, chain_monitor, logger) = build_graph();
2982                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2983                 let scorer = Scorer::new(0);
2984                 let payee = Payee::new(nodes[2]).with_features(InvoiceFeatures::known());
2985
2986                 // We will use a simple single-path route from
2987                 // our node to node2 via node0: channels {1, 3}.
2988
2989                 // First disable all other paths.
2990                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2991                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2992                         short_channel_id: 2,
2993                         timestamp: 2,
2994                         flags: 2,
2995                         cltv_expiry_delta: 0,
2996                         htlc_minimum_msat: 0,
2997                         htlc_maximum_msat: OptionalField::Present(100_000),
2998                         fee_base_msat: 0,
2999                         fee_proportional_millionths: 0,
3000                         excess_data: Vec::new()
3001                 });
3002                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3003                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3004                         short_channel_id: 12,
3005                         timestamp: 2,
3006                         flags: 2,
3007                         cltv_expiry_delta: 0,
3008                         htlc_minimum_msat: 0,
3009                         htlc_maximum_msat: OptionalField::Present(100_000),
3010                         fee_base_msat: 0,
3011                         fee_proportional_millionths: 0,
3012                         excess_data: Vec::new()
3013                 });
3014
3015                 // Make the first channel (#1) very permissive,
3016                 // and we will be testing all limits on the second channel.
3017                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3018                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3019                         short_channel_id: 1,
3020                         timestamp: 2,
3021                         flags: 0,
3022                         cltv_expiry_delta: 0,
3023                         htlc_minimum_msat: 0,
3024                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
3025                         fee_base_msat: 0,
3026                         fee_proportional_millionths: 0,
3027                         excess_data: Vec::new()
3028                 });
3029
3030                 // First, let's see if routing works if we have absolutely no idea about the available amount.
3031                 // In this case, it should be set to 250_000 sats.
3032                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3033                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3034                         short_channel_id: 3,
3035                         timestamp: 2,
3036                         flags: 0,
3037                         cltv_expiry_delta: 0,
3038                         htlc_minimum_msat: 0,
3039                         htlc_maximum_msat: OptionalField::Absent,
3040                         fee_base_msat: 0,
3041                         fee_proportional_millionths: 0,
3042                         excess_data: Vec::new()
3043                 });
3044
3045                 {
3046                         // Attempt to route more than available results in a failure.
3047                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3048                                         &our_id, &payee, &net_graph_msg_handler.network_graph, None, 250_000_001, 42, Arc::clone(&logger), &scorer) {
3049                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3050                         } else { panic!(); }
3051                 }
3052
3053                 {
3054                         // Now, attempt to route an exact amount we have should be fine.
3055                         let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 250_000_000, 42, Arc::clone(&logger), &scorer).unwrap();
3056                         assert_eq!(route.paths.len(), 1);
3057                         let path = route.paths.last().unwrap();
3058                         assert_eq!(path.len(), 2);
3059                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3060                         assert_eq!(path.last().unwrap().fee_msat, 250_000_000);
3061                 }
3062
3063                 // Check that setting outbound_capacity_msat in first_hops limits the channels.
3064                 // Disable channel #1 and use another first hop.
3065                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3066                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3067                         short_channel_id: 1,
3068                         timestamp: 3,
3069                         flags: 2,
3070                         cltv_expiry_delta: 0,
3071                         htlc_minimum_msat: 0,
3072                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
3073                         fee_base_msat: 0,
3074                         fee_proportional_millionths: 0,
3075                         excess_data: Vec::new()
3076                 });
3077
3078                 // Now, limit the first_hop by the outbound_capacity_msat of 200_000 sats.
3079                 let our_chans = vec![get_channel_details(Some(42), nodes[0].clone(), InitFeatures::from_le_bytes(vec![0b11]), 200_000_000)];
3080
3081                 {
3082                         // Attempt to route more than available results in a failure.
3083                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3084                                         &our_id, &payee, &net_graph_msg_handler.network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 200_000_001, 42, Arc::clone(&logger), &scorer) {
3085                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3086                         } else { panic!(); }
3087                 }
3088
3089                 {
3090                         // Now, attempt to route an exact amount we have should be fine.
3091                         let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, Some(&our_chans.iter().collect::<Vec<_>>()), 200_000_000, 42, Arc::clone(&logger), &scorer).unwrap();
3092                         assert_eq!(route.paths.len(), 1);
3093                         let path = route.paths.last().unwrap();
3094                         assert_eq!(path.len(), 2);
3095                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3096                         assert_eq!(path.last().unwrap().fee_msat, 200_000_000);
3097                 }
3098
3099                 // Enable channel #1 back.
3100                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3101                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3102                         short_channel_id: 1,
3103                         timestamp: 4,
3104                         flags: 0,
3105                         cltv_expiry_delta: 0,
3106                         htlc_minimum_msat: 0,
3107                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
3108                         fee_base_msat: 0,
3109                         fee_proportional_millionths: 0,
3110                         excess_data: Vec::new()
3111                 });
3112
3113
3114                 // Now let's see if routing works if we know only htlc_maximum_msat.
3115                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3116                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3117                         short_channel_id: 3,
3118                         timestamp: 3,
3119                         flags: 0,
3120                         cltv_expiry_delta: 0,
3121                         htlc_minimum_msat: 0,
3122                         htlc_maximum_msat: OptionalField::Present(15_000),
3123                         fee_base_msat: 0,
3124                         fee_proportional_millionths: 0,
3125                         excess_data: Vec::new()
3126                 });
3127
3128                 {
3129                         // Attempt to route more than available results in a failure.
3130                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3131                                         &our_id, &payee, &net_graph_msg_handler.network_graph, None, 15_001, 42, Arc::clone(&logger), &scorer) {
3132                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3133                         } else { panic!(); }
3134                 }
3135
3136                 {
3137                         // Now, attempt to route an exact amount we have should be fine.
3138                         let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 15_000, 42, Arc::clone(&logger), &scorer).unwrap();
3139                         assert_eq!(route.paths.len(), 1);
3140                         let path = route.paths.last().unwrap();
3141                         assert_eq!(path.len(), 2);
3142                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3143                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
3144                 }
3145
3146                 // Now let's see if routing works if we know only capacity from the UTXO.
3147
3148                 // We can't change UTXO capacity on the fly, so we'll disable
3149                 // the existing channel and add another one with the capacity we need.
3150                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3151                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3152                         short_channel_id: 3,
3153                         timestamp: 4,
3154                         flags: 2,
3155                         cltv_expiry_delta: 0,
3156                         htlc_minimum_msat: 0,
3157                         htlc_maximum_msat: OptionalField::Absent,
3158                         fee_base_msat: 0,
3159                         fee_proportional_millionths: 0,
3160                         excess_data: Vec::new()
3161                 });
3162
3163                 let good_script = Builder::new().push_opcode(opcodes::all::OP_PUSHNUM_2)
3164                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[0]).serialize())
3165                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[2]).serialize())
3166                 .push_opcode(opcodes::all::OP_PUSHNUM_2)
3167                 .push_opcode(opcodes::all::OP_CHECKMULTISIG).into_script().to_v0_p2wsh();
3168
3169                 *chain_monitor.utxo_ret.lock().unwrap() = Ok(TxOut { value: 15, script_pubkey: good_script.clone() });
3170                 net_graph_msg_handler.add_chain_access(Some(chain_monitor));
3171
3172                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 333);
3173                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3174                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3175                         short_channel_id: 333,
3176                         timestamp: 1,
3177                         flags: 0,
3178                         cltv_expiry_delta: (3 << 8) | 1,
3179                         htlc_minimum_msat: 0,
3180                         htlc_maximum_msat: OptionalField::Absent,
3181                         fee_base_msat: 0,
3182                         fee_proportional_millionths: 0,
3183                         excess_data: Vec::new()
3184                 });
3185                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3186                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3187                         short_channel_id: 333,
3188                         timestamp: 1,
3189                         flags: 1,
3190                         cltv_expiry_delta: (3 << 8) | 2,
3191                         htlc_minimum_msat: 0,
3192                         htlc_maximum_msat: OptionalField::Absent,
3193                         fee_base_msat: 100,
3194                         fee_proportional_millionths: 0,
3195                         excess_data: Vec::new()
3196                 });
3197
3198                 {
3199                         // Attempt to route more than available results in a failure.
3200                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3201                                         &our_id, &payee, &net_graph_msg_handler.network_graph, None, 15_001, 42, Arc::clone(&logger), &scorer) {
3202                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3203                         } else { panic!(); }
3204                 }
3205
3206                 {
3207                         // Now, attempt to route an exact amount we have should be fine.
3208                         let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 15_000, 42, Arc::clone(&logger), &scorer).unwrap();
3209                         assert_eq!(route.paths.len(), 1);
3210                         let path = route.paths.last().unwrap();
3211                         assert_eq!(path.len(), 2);
3212                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3213                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
3214                 }
3215
3216                 // Now let's see if routing chooses htlc_maximum_msat over UTXO capacity.
3217                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3218                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3219                         short_channel_id: 333,
3220                         timestamp: 6,
3221                         flags: 0,
3222                         cltv_expiry_delta: 0,
3223                         htlc_minimum_msat: 0,
3224                         htlc_maximum_msat: OptionalField::Present(10_000),
3225                         fee_base_msat: 0,
3226                         fee_proportional_millionths: 0,
3227                         excess_data: Vec::new()
3228                 });
3229
3230                 {
3231                         // Attempt to route more than available results in a failure.
3232                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3233                                         &our_id, &payee, &net_graph_msg_handler.network_graph, None, 10_001, 42, Arc::clone(&logger), &scorer) {
3234                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3235                         } else { panic!(); }
3236                 }
3237
3238                 {
3239                         // Now, attempt to route an exact amount we have should be fine.
3240                         let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 10_000, 42, Arc::clone(&logger), &scorer).unwrap();
3241                         assert_eq!(route.paths.len(), 1);
3242                         let path = route.paths.last().unwrap();
3243                         assert_eq!(path.len(), 2);
3244                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3245                         assert_eq!(path.last().unwrap().fee_msat, 10_000);
3246                 }
3247         }
3248
3249         #[test]
3250         fn available_liquidity_last_hop_test() {
3251                 // Check that available liquidity properly limits the path even when only
3252                 // one of the latter hops is limited.
3253                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3254                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3255                 let scorer = Scorer::new(0);
3256                 let payee = Payee::new(nodes[3]).with_features(InvoiceFeatures::known());
3257
3258                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3259                 // {12, 13, 11} have the capacities of 100, {6} has a capacity of 50.
3260                 // Total capacity: 50 sats.
3261
3262                 // Disable other potential paths.
3263                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3264                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3265                         short_channel_id: 2,
3266                         timestamp: 2,
3267                         flags: 2,
3268                         cltv_expiry_delta: 0,
3269                         htlc_minimum_msat: 0,
3270                         htlc_maximum_msat: OptionalField::Present(100_000),
3271                         fee_base_msat: 0,
3272                         fee_proportional_millionths: 0,
3273                         excess_data: Vec::new()
3274                 });
3275                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3276                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3277                         short_channel_id: 7,
3278                         timestamp: 2,
3279                         flags: 2,
3280                         cltv_expiry_delta: 0,
3281                         htlc_minimum_msat: 0,
3282                         htlc_maximum_msat: OptionalField::Present(100_000),
3283                         fee_base_msat: 0,
3284                         fee_proportional_millionths: 0,
3285                         excess_data: Vec::new()
3286                 });
3287
3288                 // Limit capacities
3289
3290                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3291                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3292                         short_channel_id: 12,
3293                         timestamp: 2,
3294                         flags: 0,
3295                         cltv_expiry_delta: 0,
3296                         htlc_minimum_msat: 0,
3297                         htlc_maximum_msat: OptionalField::Present(100_000),
3298                         fee_base_msat: 0,
3299                         fee_proportional_millionths: 0,
3300                         excess_data: Vec::new()
3301                 });
3302                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3303                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3304                         short_channel_id: 13,
3305                         timestamp: 2,
3306                         flags: 0,
3307                         cltv_expiry_delta: 0,
3308                         htlc_minimum_msat: 0,
3309                         htlc_maximum_msat: OptionalField::Present(100_000),
3310                         fee_base_msat: 0,
3311                         fee_proportional_millionths: 0,
3312                         excess_data: Vec::new()
3313                 });
3314
3315                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3316                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3317                         short_channel_id: 6,
3318                         timestamp: 2,
3319                         flags: 0,
3320                         cltv_expiry_delta: 0,
3321                         htlc_minimum_msat: 0,
3322                         htlc_maximum_msat: OptionalField::Present(50_000),
3323                         fee_base_msat: 0,
3324                         fee_proportional_millionths: 0,
3325                         excess_data: Vec::new()
3326                 });
3327                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3328                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3329                         short_channel_id: 11,
3330                         timestamp: 2,
3331                         flags: 0,
3332                         cltv_expiry_delta: 0,
3333                         htlc_minimum_msat: 0,
3334                         htlc_maximum_msat: OptionalField::Present(100_000),
3335                         fee_base_msat: 0,
3336                         fee_proportional_millionths: 0,
3337                         excess_data: Vec::new()
3338                 });
3339                 {
3340                         // Attempt to route more than available results in a failure.
3341                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3342                                         &our_id, &payee, &net_graph_msg_handler.network_graph, None, 60_000, 42, Arc::clone(&logger), &scorer) {
3343                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3344                         } else { panic!(); }
3345                 }
3346
3347                 {
3348                         // Now, attempt to route 49 sats (just a bit below the capacity).
3349                         let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 49_000, 42, Arc::clone(&logger), &scorer).unwrap();
3350                         assert_eq!(route.paths.len(), 1);
3351                         let mut total_amount_paid_msat = 0;
3352                         for path in &route.paths {
3353                                 assert_eq!(path.len(), 4);
3354                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3355                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3356                         }
3357                         assert_eq!(total_amount_paid_msat, 49_000);
3358                 }
3359
3360                 {
3361                         // Attempt to route an exact amount is also fine
3362                         let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 50_000, 42, Arc::clone(&logger), &scorer).unwrap();
3363                         assert_eq!(route.paths.len(), 1);
3364                         let mut total_amount_paid_msat = 0;
3365                         for path in &route.paths {
3366                                 assert_eq!(path.len(), 4);
3367                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3368                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3369                         }
3370                         assert_eq!(total_amount_paid_msat, 50_000);
3371                 }
3372         }
3373
3374         #[test]
3375         fn ignore_fee_first_hop_test() {
3376                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3377                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3378                 let scorer = Scorer::new(0);
3379                 let payee = Payee::new(nodes[2]);
3380
3381                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
3382                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3383                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3384                         short_channel_id: 1,
3385                         timestamp: 2,
3386                         flags: 0,
3387                         cltv_expiry_delta: 0,
3388                         htlc_minimum_msat: 0,
3389                         htlc_maximum_msat: OptionalField::Present(100_000),
3390                         fee_base_msat: 1_000_000,
3391                         fee_proportional_millionths: 0,
3392                         excess_data: Vec::new()
3393                 });
3394                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3395                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3396                         short_channel_id: 3,
3397                         timestamp: 2,
3398                         flags: 0,
3399                         cltv_expiry_delta: 0,
3400                         htlc_minimum_msat: 0,
3401                         htlc_maximum_msat: OptionalField::Present(50_000),
3402                         fee_base_msat: 0,
3403                         fee_proportional_millionths: 0,
3404                         excess_data: Vec::new()
3405                 });
3406
3407                 {
3408                         let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 50_000, 42, Arc::clone(&logger), &scorer).unwrap();
3409                         assert_eq!(route.paths.len(), 1);
3410                         let mut total_amount_paid_msat = 0;
3411                         for path in &route.paths {
3412                                 assert_eq!(path.len(), 2);
3413                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3414                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3415                         }
3416                         assert_eq!(total_amount_paid_msat, 50_000);
3417                 }
3418         }
3419
3420         #[test]
3421         fn simple_mpp_route_test() {
3422                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3423                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3424                 let scorer = Scorer::new(0);
3425                 let payee = Payee::new(nodes[2]).with_features(InvoiceFeatures::known());
3426
3427                 // We need a route consisting of 3 paths:
3428                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
3429                 // To achieve this, the amount being transferred should be around
3430                 // the total capacity of these 3 paths.
3431
3432                 // First, we set limits on these (previously unlimited) channels.
3433                 // Their aggregate capacity will be 50 + 60 + 180 = 290 sats.
3434
3435                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
3436                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3437                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3438                         short_channel_id: 1,
3439                         timestamp: 2,
3440                         flags: 0,
3441                         cltv_expiry_delta: 0,
3442                         htlc_minimum_msat: 0,
3443                         htlc_maximum_msat: OptionalField::Present(100_000),
3444                         fee_base_msat: 0,
3445                         fee_proportional_millionths: 0,
3446                         excess_data: Vec::new()
3447                 });
3448                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3449                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3450                         short_channel_id: 3,
3451                         timestamp: 2,
3452                         flags: 0,
3453                         cltv_expiry_delta: 0,
3454                         htlc_minimum_msat: 0,
3455                         htlc_maximum_msat: OptionalField::Present(50_000),
3456                         fee_base_msat: 0,
3457                         fee_proportional_millionths: 0,
3458                         excess_data: Vec::new()
3459                 });
3460
3461                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats
3462                 // (total limit 60).
3463                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3464                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3465                         short_channel_id: 12,
3466                         timestamp: 2,
3467                         flags: 0,
3468                         cltv_expiry_delta: 0,
3469                         htlc_minimum_msat: 0,
3470                         htlc_maximum_msat: OptionalField::Present(60_000),
3471                         fee_base_msat: 0,
3472                         fee_proportional_millionths: 0,
3473                         excess_data: Vec::new()
3474                 });
3475                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3476                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3477                         short_channel_id: 13,
3478                         timestamp: 2,
3479                         flags: 0,
3480                         cltv_expiry_delta: 0,
3481                         htlc_minimum_msat: 0,
3482                         htlc_maximum_msat: OptionalField::Present(60_000),
3483                         fee_base_msat: 0,
3484                         fee_proportional_millionths: 0,
3485                         excess_data: Vec::new()
3486                 });
3487
3488                 // Path via node1 is channels {2, 4}. Limit them to 200 and 180 sats
3489                 // (total capacity 180 sats).
3490                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3491                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3492                         short_channel_id: 2,
3493                         timestamp: 2,
3494                         flags: 0,
3495                         cltv_expiry_delta: 0,
3496                         htlc_minimum_msat: 0,
3497                         htlc_maximum_msat: OptionalField::Present(200_000),
3498                         fee_base_msat: 0,
3499                         fee_proportional_millionths: 0,
3500                         excess_data: Vec::new()
3501                 });
3502                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3503                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3504                         short_channel_id: 4,
3505                         timestamp: 2,
3506                         flags: 0,
3507                         cltv_expiry_delta: 0,
3508                         htlc_minimum_msat: 0,
3509                         htlc_maximum_msat: OptionalField::Present(180_000),
3510                         fee_base_msat: 0,
3511                         fee_proportional_millionths: 0,
3512                         excess_data: Vec::new()
3513                 });
3514
3515                 {
3516                         // Attempt to route more than available results in a failure.
3517                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3518                                         &our_id, &payee, &net_graph_msg_handler.network_graph, None, 300_000, 42, Arc::clone(&logger), &scorer) {
3519                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3520                         } else { panic!(); }
3521                 }
3522
3523                 {
3524                         // Now, attempt to route 250 sats (just a bit below the capacity).
3525                         // Our algorithm should provide us with these 3 paths.
3526                         let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 250_000, 42, Arc::clone(&logger), &scorer).unwrap();
3527                         assert_eq!(route.paths.len(), 3);
3528                         let mut total_amount_paid_msat = 0;
3529                         for path in &route.paths {
3530                                 assert_eq!(path.len(), 2);
3531                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3532                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3533                         }
3534                         assert_eq!(total_amount_paid_msat, 250_000);
3535                 }
3536
3537                 {
3538                         // Attempt to route an exact amount is also fine
3539                         let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 290_000, 42, Arc::clone(&logger), &scorer).unwrap();
3540                         assert_eq!(route.paths.len(), 3);
3541                         let mut total_amount_paid_msat = 0;
3542                         for path in &route.paths {
3543                                 assert_eq!(path.len(), 2);
3544                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3545                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3546                         }
3547                         assert_eq!(total_amount_paid_msat, 290_000);
3548                 }
3549         }
3550
3551         #[test]
3552         fn long_mpp_route_test() {
3553                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3554                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3555                 let scorer = Scorer::new(0);
3556                 let payee = Payee::new(nodes[3]).with_features(InvoiceFeatures::known());
3557
3558                 // We need a route consisting of 3 paths:
3559                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
3560                 // Note that these paths overlap (channels 5, 12, 13).
3561                 // We will route 300 sats.
3562                 // Each path will have 100 sats capacity, those channels which
3563                 // are used twice will have 200 sats capacity.
3564
3565                 // Disable other potential paths.
3566                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3567                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3568                         short_channel_id: 2,
3569                         timestamp: 2,
3570                         flags: 2,
3571                         cltv_expiry_delta: 0,
3572                         htlc_minimum_msat: 0,
3573                         htlc_maximum_msat: OptionalField::Present(100_000),
3574                         fee_base_msat: 0,
3575                         fee_proportional_millionths: 0,
3576                         excess_data: Vec::new()
3577                 });
3578                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3579                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3580                         short_channel_id: 7,
3581                         timestamp: 2,
3582                         flags: 2,
3583                         cltv_expiry_delta: 0,
3584                         htlc_minimum_msat: 0,
3585                         htlc_maximum_msat: OptionalField::Present(100_000),
3586                         fee_base_msat: 0,
3587                         fee_proportional_millionths: 0,
3588                         excess_data: Vec::new()
3589                 });
3590
3591                 // Path via {node0, node2} is channels {1, 3, 5}.
3592                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3593                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3594                         short_channel_id: 1,
3595                         timestamp: 2,
3596                         flags: 0,
3597                         cltv_expiry_delta: 0,
3598                         htlc_minimum_msat: 0,
3599                         htlc_maximum_msat: OptionalField::Present(100_000),
3600                         fee_base_msat: 0,
3601                         fee_proportional_millionths: 0,
3602                         excess_data: Vec::new()
3603                 });
3604                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3605                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3606                         short_channel_id: 3,
3607                         timestamp: 2,
3608                         flags: 0,
3609                         cltv_expiry_delta: 0,
3610                         htlc_minimum_msat: 0,
3611                         htlc_maximum_msat: OptionalField::Present(100_000),
3612                         fee_base_msat: 0,
3613                         fee_proportional_millionths: 0,
3614                         excess_data: Vec::new()
3615                 });
3616
3617                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3618                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3619                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3620                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3621                         short_channel_id: 5,
3622                         timestamp: 2,
3623                         flags: 0,
3624                         cltv_expiry_delta: 0,
3625                         htlc_minimum_msat: 0,
3626                         htlc_maximum_msat: OptionalField::Present(200_000),
3627                         fee_base_msat: 0,
3628                         fee_proportional_millionths: 0,
3629                         excess_data: Vec::new()
3630                 });
3631
3632                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3633                 // Add 100 sats to the capacities of {12, 13}, because these channels
3634                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3635                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3636                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3637                         short_channel_id: 12,
3638                         timestamp: 2,
3639                         flags: 0,
3640                         cltv_expiry_delta: 0,
3641                         htlc_minimum_msat: 0,
3642                         htlc_maximum_msat: OptionalField::Present(200_000),
3643                         fee_base_msat: 0,
3644                         fee_proportional_millionths: 0,
3645                         excess_data: Vec::new()
3646                 });
3647                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3648                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3649                         short_channel_id: 13,
3650                         timestamp: 2,
3651                         flags: 0,
3652                         cltv_expiry_delta: 0,
3653                         htlc_minimum_msat: 0,
3654                         htlc_maximum_msat: OptionalField::Present(200_000),
3655                         fee_base_msat: 0,
3656                         fee_proportional_millionths: 0,
3657                         excess_data: Vec::new()
3658                 });
3659
3660                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3661                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3662                         short_channel_id: 6,
3663                         timestamp: 2,
3664                         flags: 0,
3665                         cltv_expiry_delta: 0,
3666                         htlc_minimum_msat: 0,
3667                         htlc_maximum_msat: OptionalField::Present(100_000),
3668                         fee_base_msat: 0,
3669                         fee_proportional_millionths: 0,
3670                         excess_data: Vec::new()
3671                 });
3672                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3673                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3674                         short_channel_id: 11,
3675                         timestamp: 2,
3676                         flags: 0,
3677                         cltv_expiry_delta: 0,
3678                         htlc_minimum_msat: 0,
3679                         htlc_maximum_msat: OptionalField::Present(100_000),
3680                         fee_base_msat: 0,
3681                         fee_proportional_millionths: 0,
3682                         excess_data: Vec::new()
3683                 });
3684
3685                 // Path via {node7, node2} is channels {12, 13, 5}.
3686                 // We already limited them to 200 sats (they are used twice for 100 sats).
3687                 // Nothing to do here.
3688
3689                 {
3690                         // Attempt to route more than available results in a failure.
3691                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
3692                                         &our_id, &payee, &net_graph_msg_handler.network_graph, None, 350_000, 42, Arc::clone(&logger), &scorer) {
3693                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3694                         } else { panic!(); }
3695                 }
3696
3697                 {
3698                         // Now, attempt to route 300 sats (exact amount we can route).
3699                         // Our algorithm should provide us with these 3 paths, 100 sats each.
3700                         let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 300_000, 42, Arc::clone(&logger), &scorer).unwrap();
3701                         assert_eq!(route.paths.len(), 3);
3702
3703                         let mut total_amount_paid_msat = 0;
3704                         for path in &route.paths {
3705                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3706                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3707                         }
3708                         assert_eq!(total_amount_paid_msat, 300_000);
3709                 }
3710
3711         }
3712
3713         #[test]
3714         fn mpp_cheaper_route_test() {
3715                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3716                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3717                 let scorer = Scorer::new(0);
3718                 let payee = Payee::new(nodes[3]).with_features(InvoiceFeatures::known());
3719
3720                 // This test checks that if we have two cheaper paths and one more expensive path,
3721                 // so that liquidity-wise any 2 of 3 combination is sufficient,
3722                 // two cheaper paths will be taken.
3723                 // These paths have equal available liquidity.
3724
3725                 // We need a combination of 3 paths:
3726                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
3727                 // Note that these paths overlap (channels 5, 12, 13).
3728                 // Each path will have 100 sats capacity, those channels which
3729                 // are used twice will have 200 sats capacity.
3730
3731                 // Disable other potential paths.
3732                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3733                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3734                         short_channel_id: 2,
3735                         timestamp: 2,
3736                         flags: 2,
3737                         cltv_expiry_delta: 0,
3738                         htlc_minimum_msat: 0,
3739                         htlc_maximum_msat: OptionalField::Present(100_000),
3740                         fee_base_msat: 0,
3741                         fee_proportional_millionths: 0,
3742                         excess_data: Vec::new()
3743                 });
3744                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3745                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3746                         short_channel_id: 7,
3747                         timestamp: 2,
3748                         flags: 2,
3749                         cltv_expiry_delta: 0,
3750                         htlc_minimum_msat: 0,
3751                         htlc_maximum_msat: OptionalField::Present(100_000),
3752                         fee_base_msat: 0,
3753                         fee_proportional_millionths: 0,
3754                         excess_data: Vec::new()
3755                 });
3756
3757                 // Path via {node0, node2} is channels {1, 3, 5}.
3758                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3759                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3760                         short_channel_id: 1,
3761                         timestamp: 2,
3762                         flags: 0,
3763                         cltv_expiry_delta: 0,
3764                         htlc_minimum_msat: 0,
3765                         htlc_maximum_msat: OptionalField::Present(100_000),
3766                         fee_base_msat: 0,
3767                         fee_proportional_millionths: 0,
3768                         excess_data: Vec::new()
3769                 });
3770                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3771                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3772                         short_channel_id: 3,
3773                         timestamp: 2,
3774                         flags: 0,
3775                         cltv_expiry_delta: 0,
3776                         htlc_minimum_msat: 0,
3777                         htlc_maximum_msat: OptionalField::Present(100_000),
3778                         fee_base_msat: 0,
3779                         fee_proportional_millionths: 0,
3780                         excess_data: Vec::new()
3781                 });
3782
3783                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3784                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3785                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3786                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3787                         short_channel_id: 5,
3788                         timestamp: 2,
3789                         flags: 0,
3790                         cltv_expiry_delta: 0,
3791                         htlc_minimum_msat: 0,
3792                         htlc_maximum_msat: OptionalField::Present(200_000),
3793                         fee_base_msat: 0,
3794                         fee_proportional_millionths: 0,
3795                         excess_data: Vec::new()
3796                 });
3797
3798                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3799                 // Add 100 sats to the capacities of {12, 13}, because these channels
3800                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3801                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3802                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3803                         short_channel_id: 12,
3804                         timestamp: 2,
3805                         flags: 0,
3806                         cltv_expiry_delta: 0,
3807                         htlc_minimum_msat: 0,
3808                         htlc_maximum_msat: OptionalField::Present(200_000),
3809                         fee_base_msat: 0,
3810                         fee_proportional_millionths: 0,
3811                         excess_data: Vec::new()
3812                 });
3813                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3814                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3815                         short_channel_id: 13,
3816                         timestamp: 2,
3817                         flags: 0,
3818                         cltv_expiry_delta: 0,
3819                         htlc_minimum_msat: 0,
3820                         htlc_maximum_msat: OptionalField::Present(200_000),
3821                         fee_base_msat: 0,
3822                         fee_proportional_millionths: 0,
3823                         excess_data: Vec::new()
3824                 });
3825
3826                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3827                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3828                         short_channel_id: 6,
3829                         timestamp: 2,
3830                         flags: 0,
3831                         cltv_expiry_delta: 0,
3832                         htlc_minimum_msat: 0,
3833                         htlc_maximum_msat: OptionalField::Present(100_000),
3834                         fee_base_msat: 1_000,
3835                         fee_proportional_millionths: 0,
3836                         excess_data: Vec::new()
3837                 });
3838                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3839                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3840                         short_channel_id: 11,
3841                         timestamp: 2,
3842                         flags: 0,
3843                         cltv_expiry_delta: 0,
3844                         htlc_minimum_msat: 0,
3845                         htlc_maximum_msat: OptionalField::Present(100_000),
3846                         fee_base_msat: 0,
3847                         fee_proportional_millionths: 0,
3848                         excess_data: Vec::new()
3849                 });
3850
3851                 // Path via {node7, node2} is channels {12, 13, 5}.
3852                 // We already limited them to 200 sats (they are used twice for 100 sats).
3853                 // Nothing to do here.
3854
3855                 {
3856                         // Now, attempt to route 180 sats.
3857                         // Our algorithm should provide us with these 2 paths.
3858                         let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 180_000, 42, Arc::clone(&logger), &scorer).unwrap();
3859                         assert_eq!(route.paths.len(), 2);
3860
3861                         let mut total_value_transferred_msat = 0;
3862                         let mut total_paid_msat = 0;
3863                         for path in &route.paths {
3864                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3865                                 total_value_transferred_msat += path.last().unwrap().fee_msat;
3866                                 for hop in path {
3867                                         total_paid_msat += hop.fee_msat;
3868                                 }
3869                         }
3870                         // If we paid fee, this would be higher.
3871                         assert_eq!(total_value_transferred_msat, 180_000);
3872                         let total_fees_paid = total_paid_msat - total_value_transferred_msat;
3873                         assert_eq!(total_fees_paid, 0);
3874                 }
3875         }
3876
3877         #[test]
3878         fn fees_on_mpp_route_test() {
3879                 // This test makes sure that MPP algorithm properly takes into account
3880                 // fees charged on the channels, by making the fees impactful:
3881                 // if the fee is not properly accounted for, the behavior is different.
3882                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3883                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3884                 let scorer = Scorer::new(0);
3885                 let payee = Payee::new(nodes[3]).with_features(InvoiceFeatures::known());
3886
3887                 // We need a route consisting of 2 paths:
3888                 // From our node to node3 via {node0, node2} and {node7, node2, node4}.
3889                 // We will route 200 sats, Each path will have 100 sats capacity.
3890
3891                 // This test is not particularly stable: e.g.,
3892                 // there's a way to route via {node0, node2, node4}.
3893                 // It works while pathfinding is deterministic, but can be broken otherwise.
3894                 // It's fine to ignore this concern for now.
3895
3896                 // Disable other potential paths.
3897                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3898                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3899                         short_channel_id: 2,
3900                         timestamp: 2,
3901                         flags: 2,
3902                         cltv_expiry_delta: 0,
3903                         htlc_minimum_msat: 0,
3904                         htlc_maximum_msat: OptionalField::Present(100_000),
3905                         fee_base_msat: 0,
3906                         fee_proportional_millionths: 0,
3907                         excess_data: Vec::new()
3908                 });
3909
3910                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3911                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3912                         short_channel_id: 7,
3913                         timestamp: 2,
3914                         flags: 2,
3915                         cltv_expiry_delta: 0,
3916                         htlc_minimum_msat: 0,
3917                         htlc_maximum_msat: OptionalField::Present(100_000),
3918                         fee_base_msat: 0,
3919                         fee_proportional_millionths: 0,
3920                         excess_data: Vec::new()
3921                 });
3922
3923                 // Path via {node0, node2} is channels {1, 3, 5}.
3924                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3925                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3926                         short_channel_id: 1,
3927                         timestamp: 2,
3928                         flags: 0,
3929                         cltv_expiry_delta: 0,
3930                         htlc_minimum_msat: 0,
3931                         htlc_maximum_msat: OptionalField::Present(100_000),
3932                         fee_base_msat: 0,
3933                         fee_proportional_millionths: 0,
3934                         excess_data: Vec::new()
3935                 });
3936                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3937                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3938                         short_channel_id: 3,
3939                         timestamp: 2,
3940                         flags: 0,
3941                         cltv_expiry_delta: 0,
3942                         htlc_minimum_msat: 0,
3943                         htlc_maximum_msat: OptionalField::Present(100_000),
3944                         fee_base_msat: 0,
3945                         fee_proportional_millionths: 0,
3946                         excess_data: Vec::new()
3947                 });
3948
3949                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3950                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3951                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3952                         short_channel_id: 5,
3953                         timestamp: 2,
3954                         flags: 0,
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                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3964                 // All channels should be 100 sats capacity. But for the fee experiment,
3965                 // we'll add absolute fee of 150 sats paid for the use channel 6 (paid to node2 on channel 13).
3966                 // Since channel 12 allows to deliver only 250 sats to channel 13, channel 13 can transfer only
3967                 // 100 sats (and pay 150 sats in fees for the use of channel 6),
3968                 // so no matter how large are other channels,
3969                 // the whole path will be limited by 100 sats with just these 2 conditions:
3970                 // - channel 12 capacity is 250 sats
3971                 // - fee for channel 6 is 150 sats
3972                 // Let's test this by enforcing these 2 conditions and removing other limits.
3973                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3974                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3975                         short_channel_id: 12,
3976                         timestamp: 2,
3977                         flags: 0,
3978                         cltv_expiry_delta: 0,
3979                         htlc_minimum_msat: 0,
3980                         htlc_maximum_msat: OptionalField::Present(250_000),
3981                         fee_base_msat: 0,
3982                         fee_proportional_millionths: 0,
3983                         excess_data: Vec::new()
3984                 });
3985                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3986                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3987                         short_channel_id: 13,
3988                         timestamp: 2,
3989                         flags: 0,
3990                         cltv_expiry_delta: 0,
3991                         htlc_minimum_msat: 0,
3992                         htlc_maximum_msat: OptionalField::Absent,
3993                         fee_base_msat: 0,
3994                         fee_proportional_millionths: 0,
3995                         excess_data: Vec::new()
3996                 });
3997
3998                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3999                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4000                         short_channel_id: 6,
4001                         timestamp: 2,
4002                         flags: 0,
4003                         cltv_expiry_delta: 0,
4004                         htlc_minimum_msat: 0,
4005                         htlc_maximum_msat: OptionalField::Absent,
4006                         fee_base_msat: 150_000,
4007                         fee_proportional_millionths: 0,
4008                         excess_data: Vec::new()
4009                 });
4010                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
4011                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4012                         short_channel_id: 11,
4013                         timestamp: 2,
4014                         flags: 0,
4015                         cltv_expiry_delta: 0,
4016                         htlc_minimum_msat: 0,
4017                         htlc_maximum_msat: OptionalField::Absent,
4018                         fee_base_msat: 0,
4019                         fee_proportional_millionths: 0,
4020                         excess_data: Vec::new()
4021                 });
4022
4023                 {
4024                         // Attempt to route more than available results in a failure.
4025                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
4026                                         &our_id, &payee, &net_graph_msg_handler.network_graph, None, 210_000, 42, Arc::clone(&logger), &scorer) {
4027                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
4028                         } else { panic!(); }
4029                 }
4030
4031                 {
4032                         // Now, attempt to route 200 sats (exact amount we can route).
4033                         let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 200_000, 42, Arc::clone(&logger), &scorer).unwrap();
4034                         assert_eq!(route.paths.len(), 2);
4035
4036                         let mut total_amount_paid_msat = 0;
4037                         for path in &route.paths {
4038                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
4039                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
4040                         }
4041                         assert_eq!(total_amount_paid_msat, 200_000);
4042                         assert_eq!(route.get_total_fees(), 150_000);
4043                 }
4044
4045         }
4046
4047         #[test]
4048         fn drop_lowest_channel_mpp_route_test() {
4049                 // This test checks that low-capacity channel is dropped when after
4050                 // path finding we realize that we found more capacity than we need.
4051                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
4052                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
4053                 let scorer = Scorer::new(0);
4054                 let payee = Payee::new(nodes[2]).with_features(InvoiceFeatures::known());
4055
4056                 // We need a route consisting of 3 paths:
4057                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
4058
4059                 // The first and the second paths should be sufficient, but the third should be
4060                 // cheaper, so that we select it but drop later.
4061
4062                 // First, we set limits on these (previously unlimited) channels.
4063                 // Their aggregate capacity will be 50 + 60 + 20 = 130 sats.
4064
4065                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50);
4066                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4067                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4068                         short_channel_id: 1,
4069                         timestamp: 2,
4070                         flags: 0,
4071                         cltv_expiry_delta: 0,
4072                         htlc_minimum_msat: 0,
4073                         htlc_maximum_msat: OptionalField::Present(100_000),
4074                         fee_base_msat: 0,
4075                         fee_proportional_millionths: 0,
4076                         excess_data: Vec::new()
4077                 });
4078                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
4079                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4080                         short_channel_id: 3,
4081                         timestamp: 2,
4082                         flags: 0,
4083                         cltv_expiry_delta: 0,
4084                         htlc_minimum_msat: 0,
4085                         htlc_maximum_msat: OptionalField::Present(50_000),
4086                         fee_base_msat: 100,
4087                         fee_proportional_millionths: 0,
4088                         excess_data: Vec::new()
4089                 });
4090
4091                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats (total limit 60);
4092                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4093                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4094                         short_channel_id: 12,
4095                         timestamp: 2,
4096                         flags: 0,
4097                         cltv_expiry_delta: 0,
4098                         htlc_minimum_msat: 0,
4099                         htlc_maximum_msat: OptionalField::Present(60_000),
4100                         fee_base_msat: 100,
4101                         fee_proportional_millionths: 0,
4102                         excess_data: Vec::new()
4103                 });
4104                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
4105                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4106                         short_channel_id: 13,
4107                         timestamp: 2,
4108                         flags: 0,
4109                         cltv_expiry_delta: 0,
4110                         htlc_minimum_msat: 0,
4111                         htlc_maximum_msat: OptionalField::Present(60_000),
4112                         fee_base_msat: 0,
4113                         fee_proportional_millionths: 0,
4114                         excess_data: Vec::new()
4115                 });
4116
4117                 // Path via node1 is channels {2, 4}. Limit them to 20 and 20 sats (total capacity 20 sats).
4118                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4119                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4120                         short_channel_id: 2,
4121                         timestamp: 2,
4122                         flags: 0,
4123                         cltv_expiry_delta: 0,
4124                         htlc_minimum_msat: 0,
4125                         htlc_maximum_msat: OptionalField::Present(20_000),
4126                         fee_base_msat: 0,
4127                         fee_proportional_millionths: 0,
4128                         excess_data: Vec::new()
4129                 });
4130                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
4131                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4132                         short_channel_id: 4,
4133                         timestamp: 2,
4134                         flags: 0,
4135                         cltv_expiry_delta: 0,
4136                         htlc_minimum_msat: 0,
4137                         htlc_maximum_msat: OptionalField::Present(20_000),
4138                         fee_base_msat: 0,
4139                         fee_proportional_millionths: 0,
4140                         excess_data: Vec::new()
4141                 });
4142
4143                 {
4144                         // Attempt to route more than available results in a failure.
4145                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(
4146                                         &our_id, &payee, &net_graph_msg_handler.network_graph, None, 150_000, 42, Arc::clone(&logger), &scorer) {
4147                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
4148                         } else { panic!(); }
4149                 }
4150
4151                 {
4152                         // Now, attempt to route 125 sats (just a bit below the capacity of 3 channels).
4153                         // Our algorithm should provide us with these 3 paths.
4154                         let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 125_000, 42, Arc::clone(&logger), &scorer).unwrap();
4155                         assert_eq!(route.paths.len(), 3);
4156                         let mut total_amount_paid_msat = 0;
4157                         for path in &route.paths {
4158                                 assert_eq!(path.len(), 2);
4159                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
4160                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
4161                         }
4162                         assert_eq!(total_amount_paid_msat, 125_000);
4163                 }
4164
4165                 {
4166                         // Attempt to route without the last small cheap channel
4167                         let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 90_000, 42, Arc::clone(&logger), &scorer).unwrap();
4168                         assert_eq!(route.paths.len(), 2);
4169                         let mut total_amount_paid_msat = 0;
4170                         for path in &route.paths {
4171                                 assert_eq!(path.len(), 2);
4172                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
4173                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
4174                         }
4175                         assert_eq!(total_amount_paid_msat, 90_000);
4176                 }
4177         }
4178
4179         #[test]
4180         fn min_criteria_consistency() {
4181                 // Test that we don't use an inconsistent metric between updating and walking nodes during
4182                 // our Dijkstra's pass. In the initial version of MPP, the "best source" for a given node
4183                 // was updated with a different criterion from the heap sorting, resulting in loops in
4184                 // calculated paths. We test for that specific case here.
4185
4186                 // We construct a network that looks like this:
4187                 //
4188                 //            node2 -1(3)2- node3
4189                 //              2          2
4190                 //               (2)     (4)
4191                 //                  1   1
4192                 //    node1 -1(5)2- node4 -1(1)2- node6
4193                 //    2
4194                 //   (6)
4195                 //        1
4196                 // our_node
4197                 //
4198                 // We create a loop on the side of our real path - our destination is node 6, with a
4199                 // previous hop of node 4. From 4, the cheapest previous path is channel 2 from node 2,
4200                 // followed by node 3 over channel 3. Thereafter, the cheapest next-hop is back to node 4
4201                 // (this time over channel 4). Channel 4 has 0 htlc_minimum_msat whereas channel 1 (the
4202                 // other channel with a previous-hop of node 4) has a high (but irrelevant to the overall
4203                 // payment) htlc_minimum_msat. In the original algorithm, this resulted in node4's
4204                 // "previous hop" being set to node 3, creating a loop in the path.
4205                 let secp_ctx = Secp256k1::new();
4206                 let logger = Arc::new(test_utils::TestLogger::new());
4207                 let network_graph = NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash());
4208                 let net_graph_msg_handler = NetGraphMsgHandler::new(network_graph, None, Arc::clone(&logger));
4209                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
4210                 let scorer = Scorer::new(0);
4211                 let payee = Payee::new(nodes[6]);
4212
4213                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
4214                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4215                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4216                         short_channel_id: 6,
4217                         timestamp: 1,
4218                         flags: 0,
4219                         cltv_expiry_delta: (6 << 8) | 0,
4220                         htlc_minimum_msat: 0,
4221                         htlc_maximum_msat: OptionalField::Absent,
4222                         fee_base_msat: 0,
4223                         fee_proportional_millionths: 0,
4224                         excess_data: Vec::new()
4225                 });
4226                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
4227
4228                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
4229                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
4230                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4231                         short_channel_id: 5,
4232                         timestamp: 1,
4233                         flags: 0,
4234                         cltv_expiry_delta: (5 << 8) | 0,
4235                         htlc_minimum_msat: 0,
4236                         htlc_maximum_msat: OptionalField::Absent,
4237                         fee_base_msat: 100,
4238                         fee_proportional_millionths: 0,
4239                         excess_data: Vec::new()
4240                 });
4241                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
4242
4243                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
4244                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
4245                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4246                         short_channel_id: 4,
4247                         timestamp: 1,
4248                         flags: 0,
4249                         cltv_expiry_delta: (4 << 8) | 0,
4250                         htlc_minimum_msat: 0,
4251                         htlc_maximum_msat: OptionalField::Absent,
4252                         fee_base_msat: 0,
4253                         fee_proportional_millionths: 0,
4254                         excess_data: Vec::new()
4255                 });
4256                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
4257
4258                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
4259                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
4260                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4261                         short_channel_id: 3,
4262                         timestamp: 1,
4263                         flags: 0,
4264                         cltv_expiry_delta: (3 << 8) | 0,
4265                         htlc_minimum_msat: 0,
4266                         htlc_maximum_msat: OptionalField::Absent,
4267                         fee_base_msat: 0,
4268                         fee_proportional_millionths: 0,
4269                         excess_data: Vec::new()
4270                 });
4271                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
4272
4273                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
4274                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
4275                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4276                         short_channel_id: 2,
4277                         timestamp: 1,
4278                         flags: 0,
4279                         cltv_expiry_delta: (2 << 8) | 0,
4280                         htlc_minimum_msat: 0,
4281                         htlc_maximum_msat: OptionalField::Absent,
4282                         fee_base_msat: 0,
4283                         fee_proportional_millionths: 0,
4284                         excess_data: Vec::new()
4285                 });
4286
4287                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[6], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
4288                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
4289                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4290                         short_channel_id: 1,
4291                         timestamp: 1,
4292                         flags: 0,
4293                         cltv_expiry_delta: (1 << 8) | 0,
4294                         htlc_minimum_msat: 100,
4295                         htlc_maximum_msat: OptionalField::Absent,
4296                         fee_base_msat: 0,
4297                         fee_proportional_millionths: 0,
4298                         excess_data: Vec::new()
4299                 });
4300                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[6], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
4301
4302                 {
4303                         // Now ensure the route flows simply over nodes 1 and 4 to 6.
4304                         let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 10_000, 42, Arc::clone(&logger), &scorer).unwrap();
4305                         assert_eq!(route.paths.len(), 1);
4306                         assert_eq!(route.paths[0].len(), 3);
4307
4308                         assert_eq!(route.paths[0][0].pubkey, nodes[1]);
4309                         assert_eq!(route.paths[0][0].short_channel_id, 6);
4310                         assert_eq!(route.paths[0][0].fee_msat, 100);
4311                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (5 << 8) | 0);
4312                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(1));
4313                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(6));
4314
4315                         assert_eq!(route.paths[0][1].pubkey, nodes[4]);
4316                         assert_eq!(route.paths[0][1].short_channel_id, 5);
4317                         assert_eq!(route.paths[0][1].fee_msat, 0);
4318                         assert_eq!(route.paths[0][1].cltv_expiry_delta, (1 << 8) | 0);
4319                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(4));
4320                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(5));
4321
4322                         assert_eq!(route.paths[0][2].pubkey, nodes[6]);
4323                         assert_eq!(route.paths[0][2].short_channel_id, 1);
4324                         assert_eq!(route.paths[0][2].fee_msat, 10_000);
4325                         assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
4326                         assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
4327                         assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(1));
4328                 }
4329         }
4330
4331
4332         #[test]
4333         fn exact_fee_liquidity_limit() {
4334                 // Test that if, while walking the graph, we find a hop that has exactly enough liquidity
4335                 // for us, including later hop fees, we take it. In the first version of our MPP algorithm
4336                 // we calculated fees on a higher value, resulting in us ignoring such paths.
4337                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
4338                 let (our_privkey, our_id, _, nodes) = get_nodes(&secp_ctx);
4339                 let scorer = Scorer::new(0);
4340                 let payee = Payee::new(nodes[2]);
4341
4342                 // We modify the graph to set the htlc_maximum of channel 2 to below the value we wish to
4343                 // send.
4344                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4345                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4346                         short_channel_id: 2,
4347                         timestamp: 2,
4348                         flags: 0,
4349                         cltv_expiry_delta: 0,
4350                         htlc_minimum_msat: 0,
4351                         htlc_maximum_msat: OptionalField::Present(85_000),
4352                         fee_base_msat: 0,
4353                         fee_proportional_millionths: 0,
4354                         excess_data: Vec::new()
4355                 });
4356
4357                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4358                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4359                         short_channel_id: 12,
4360                         timestamp: 2,
4361                         flags: 0,
4362                         cltv_expiry_delta: (4 << 8) | 1,
4363                         htlc_minimum_msat: 0,
4364                         htlc_maximum_msat: OptionalField::Present(270_000),
4365                         fee_base_msat: 0,
4366                         fee_proportional_millionths: 1000000,
4367                         excess_data: Vec::new()
4368                 });
4369
4370                 {
4371                         // Now, attempt to route 90 sats, which is exactly 90 sats at the last hop, plus the
4372                         // 200% fee charged channel 13 in the 1-to-2 direction.
4373                         let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 90_000, 42, Arc::clone(&logger), &scorer).unwrap();
4374                         assert_eq!(route.paths.len(), 1);
4375                         assert_eq!(route.paths[0].len(), 2);
4376
4377                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
4378                         assert_eq!(route.paths[0][0].short_channel_id, 12);
4379                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
4380                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
4381                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
4382                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
4383
4384                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
4385                         assert_eq!(route.paths[0][1].short_channel_id, 13);
4386                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
4387                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
4388                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
4389                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
4390                 }
4391         }
4392
4393         #[test]
4394         fn htlc_max_reduction_below_min() {
4395                 // Test that if, while walking the graph, we reduce the value being sent to meet an
4396                 // htlc_maximum_msat, we don't end up undershooting a later htlc_minimum_msat. In the
4397                 // initial version of MPP we'd accept such routes but reject them while recalculating fees,
4398                 // resulting in us thinking there is no possible path, even if other paths exist.
4399                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
4400                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
4401                 let scorer = Scorer::new(0);
4402                 let payee = Payee::new(nodes[2]).with_features(InvoiceFeatures::known());
4403
4404                 // We modify the graph to set the htlc_minimum of channel 2 and 4 as needed - channel 2
4405                 // gets an htlc_maximum_msat of 80_000 and channel 4 an htlc_minimum_msat of 90_000. We
4406                 // then try to send 90_000.
4407                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4408                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4409                         short_channel_id: 2,
4410                         timestamp: 2,
4411                         flags: 0,
4412                         cltv_expiry_delta: 0,
4413                         htlc_minimum_msat: 0,
4414                         htlc_maximum_msat: OptionalField::Present(80_000),
4415                         fee_base_msat: 0,
4416                         fee_proportional_millionths: 0,
4417                         excess_data: Vec::new()
4418                 });
4419                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
4420                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4421                         short_channel_id: 4,
4422                         timestamp: 2,
4423                         flags: 0,
4424                         cltv_expiry_delta: (4 << 8) | 1,
4425                         htlc_minimum_msat: 90_000,
4426                         htlc_maximum_msat: OptionalField::Absent,
4427                         fee_base_msat: 0,
4428                         fee_proportional_millionths: 0,
4429                         excess_data: Vec::new()
4430                 });
4431
4432                 {
4433                         // Now, attempt to route 90 sats, hitting the htlc_minimum on channel 4, but
4434                         // overshooting the htlc_maximum on channel 2. Thus, we should pick the (absurdly
4435                         // expensive) channels 12-13 path.
4436                         let route = get_route(&our_id, &payee, &net_graph_msg_handler.network_graph, None, 90_000, 42, Arc::clone(&logger), &scorer).unwrap();
4437                         assert_eq!(route.paths.len(), 1);
4438                         assert_eq!(route.paths[0].len(), 2);
4439
4440                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
4441                         assert_eq!(route.paths[0][0].short_channel_id, 12);
4442                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
4443                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
4444                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
4445                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
4446
4447                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
4448                         assert_eq!(route.paths[0][1].short_channel_id, 13);
4449                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
4450                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
4451                         assert_eq!(route.paths[0][1].node_features.le_flags(), InvoiceFeatures::known().le_flags());
4452                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
4453                 }
4454         }
4455
4456         #[test]
4457         fn multiple_direct_first_hops() {
4458                 // Previously we'd only ever considered one first hop path per counterparty.
4459                 // However, as we don't restrict users to one channel per peer, we really need to support
4460                 // looking at all first hop paths.
4461                 // Here we test that we do not ignore all-but-the-last first hop paths per counterparty (as
4462                 // we used to do by overwriting the `first_hop_targets` hashmap entry) and that we can MPP
4463                 // route over multiple channels with the same first hop.
4464                 let secp_ctx = Secp256k1::new();
4465                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
4466                 let logger = Arc::new(test_utils::TestLogger::new());
4467                 let network_graph = NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash());
4468                 let scorer = Scorer::new(0);
4469                 let payee = Payee::new(nodes[0]).with_features(InvoiceFeatures::known());
4470
4471                 {
4472                         let route = get_route(&our_id, &payee, &network_graph, Some(&[
4473                                 &get_channel_details(Some(3), nodes[0], InitFeatures::known(), 200_000),
4474                                 &get_channel_details(Some(2), nodes[0], InitFeatures::known(), 10_000),
4475                         ]), 100_000, 42, Arc::clone(&logger), &scorer).unwrap();
4476                         assert_eq!(route.paths.len(), 1);
4477                         assert_eq!(route.paths[0].len(), 1);
4478
4479                         assert_eq!(route.paths[0][0].pubkey, nodes[0]);
4480                         assert_eq!(route.paths[0][0].short_channel_id, 3);
4481                         assert_eq!(route.paths[0][0].fee_msat, 100_000);
4482                 }
4483                 {
4484                         let route = get_route(&our_id, &payee, &network_graph, Some(&[
4485                                 &get_channel_details(Some(3), nodes[0], InitFeatures::known(), 50_000),
4486                                 &get_channel_details(Some(2), nodes[0], InitFeatures::known(), 50_000),
4487                         ]), 100_000, 42, Arc::clone(&logger), &scorer).unwrap();
4488                         assert_eq!(route.paths.len(), 2);
4489                         assert_eq!(route.paths[0].len(), 1);
4490                         assert_eq!(route.paths[1].len(), 1);
4491
4492                         assert_eq!(route.paths[0][0].pubkey, nodes[0]);
4493                         assert_eq!(route.paths[0][0].short_channel_id, 3);
4494                         assert_eq!(route.paths[0][0].fee_msat, 50_000);
4495
4496                         assert_eq!(route.paths[1][0].pubkey, nodes[0]);
4497                         assert_eq!(route.paths[1][0].short_channel_id, 2);
4498                         assert_eq!(route.paths[1][0].fee_msat, 50_000);
4499                 }
4500         }
4501
4502         #[test]
4503         fn prefers_shorter_route_with_higher_fees() {
4504                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
4505                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
4506                 let payee = Payee::new(nodes[6]).with_route_hints(last_hops(&nodes));
4507
4508                 // Without penalizing each hop 100 msats, a longer path with lower fees is chosen.
4509                 let scorer = Scorer::new(0);
4510                 let route = get_route(
4511                         &our_id, &payee, &net_graph_msg_handler.network_graph, None, 100, 42,
4512                         Arc::clone(&logger), &scorer
4513                 ).unwrap();
4514                 let path = route.paths[0].iter().map(|hop| hop.short_channel_id).collect::<Vec<_>>();
4515
4516                 assert_eq!(route.get_total_fees(), 100);
4517                 assert_eq!(route.get_total_amount(), 100);
4518                 assert_eq!(path, vec![2, 4, 6, 11, 8]);
4519
4520                 // Applying a 100 msat penalty to each hop results in taking channels 7 and 10 to nodes[6]
4521                 // from nodes[2] rather than channel 6, 11, and 8, even though the longer path is cheaper.
4522                 let scorer = Scorer::new(100);
4523                 let route = get_route(
4524                         &our_id, &payee, &net_graph_msg_handler.network_graph, None, 100, 42,
4525                         Arc::clone(&logger), &scorer
4526                 ).unwrap();
4527                 let path = route.paths[0].iter().map(|hop| hop.short_channel_id).collect::<Vec<_>>();
4528
4529                 assert_eq!(route.get_total_fees(), 300);
4530                 assert_eq!(route.get_total_amount(), 100);
4531                 assert_eq!(path, vec![2, 4, 7, 10]);
4532         }
4533
4534         struct BadChannelScorer {
4535                 short_channel_id: u64,
4536         }
4537
4538         impl routing::Score for BadChannelScorer {
4539                 fn channel_penalty_msat(&self, short_channel_id: u64, _source: &NodeId, _target: &NodeId) -> u64 {
4540                         if short_channel_id == self.short_channel_id { u64::max_value() } else { 0 }
4541                 }
4542         }
4543
4544         struct BadNodeScorer {
4545                 node_id: NodeId,
4546         }
4547
4548         impl routing::Score for BadNodeScorer {
4549                 fn channel_penalty_msat(&self, _short_channel_id: u64, _source: &NodeId, target: &NodeId) -> u64 {
4550                         if *target == self.node_id { u64::max_value() } else { 0 }
4551                 }
4552         }
4553
4554         #[test]
4555         fn avoids_routing_through_bad_channels_and_nodes() {
4556                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
4557                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
4558                 let payee = Payee::new(nodes[6]).with_route_hints(last_hops(&nodes));
4559
4560                 // A path to nodes[6] exists when no penalties are applied to any channel.
4561                 let scorer = Scorer::new(0);
4562                 let route = get_route(
4563                         &our_id, &payee, &net_graph_msg_handler.network_graph, None, 100, 42,
4564                         Arc::clone(&logger), &scorer
4565                 ).unwrap();
4566                 let path = route.paths[0].iter().map(|hop| hop.short_channel_id).collect::<Vec<_>>();
4567
4568                 assert_eq!(route.get_total_fees(), 100);
4569                 assert_eq!(route.get_total_amount(), 100);
4570                 assert_eq!(path, vec![2, 4, 6, 11, 8]);
4571
4572                 // A different path to nodes[6] exists if channel 6 cannot be routed over.
4573                 let scorer = BadChannelScorer { short_channel_id: 6 };
4574                 let route = get_route(
4575                         &our_id, &payee, &net_graph_msg_handler.network_graph, None, 100, 42,
4576                         Arc::clone(&logger), &scorer
4577                 ).unwrap();
4578                 let path = route.paths[0].iter().map(|hop| hop.short_channel_id).collect::<Vec<_>>();
4579
4580                 assert_eq!(route.get_total_fees(), 300);
4581                 assert_eq!(route.get_total_amount(), 100);
4582                 assert_eq!(path, vec![2, 4, 7, 10]);
4583
4584                 // A path to nodes[6] does not exist if nodes[2] cannot be routed through.
4585                 let scorer = BadNodeScorer { node_id: NodeId::from_pubkey(&nodes[2]) };
4586                 match get_route(
4587                         &our_id, &payee, &net_graph_msg_handler.network_graph, None, 100, 42,
4588                         Arc::clone(&logger), &scorer
4589                 ) {
4590                         Err(LightningError { err, .. } ) => {
4591                                 assert_eq!(err, "Failed to find a path to the given destination");
4592                         },
4593                         Ok(_) => panic!("Expected error"),
4594                 }
4595         }
4596
4597         #[test]
4598         fn total_fees_single_path() {
4599                 let route = Route {
4600                         paths: vec![vec![
4601                                 RouteHop {
4602                                         pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
4603                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4604                                         short_channel_id: 0, fee_msat: 100, cltv_expiry_delta: 0
4605                                 },
4606                                 RouteHop {
4607                                         pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
4608                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4609                                         short_channel_id: 0, fee_msat: 150, cltv_expiry_delta: 0
4610                                 },
4611                                 RouteHop {
4612                                         pubkey: PublicKey::from_slice(&hex::decode("027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007").unwrap()[..]).unwrap(),
4613                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4614                                         short_channel_id: 0, fee_msat: 225, cltv_expiry_delta: 0
4615                                 },
4616                         ]],
4617                         payee: None,
4618                 };
4619
4620                 assert_eq!(route.get_total_fees(), 250);
4621                 assert_eq!(route.get_total_amount(), 225);
4622         }
4623
4624         #[test]
4625         fn total_fees_multi_path() {
4626                 let route = Route {
4627                         paths: vec![vec![
4628                                 RouteHop {
4629                                         pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
4630                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4631                                         short_channel_id: 0, fee_msat: 100, cltv_expiry_delta: 0
4632                                 },
4633                                 RouteHop {
4634                                         pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
4635                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4636                                         short_channel_id: 0, fee_msat: 150, cltv_expiry_delta: 0
4637                                 },
4638                         ],vec![
4639                                 RouteHop {
4640                                         pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
4641                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4642                                         short_channel_id: 0, fee_msat: 100, cltv_expiry_delta: 0
4643                                 },
4644                                 RouteHop {
4645                                         pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
4646                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4647                                         short_channel_id: 0, fee_msat: 150, cltv_expiry_delta: 0
4648                                 },
4649                         ]],
4650                         payee: None,
4651                 };
4652
4653                 assert_eq!(route.get_total_fees(), 200);
4654                 assert_eq!(route.get_total_amount(), 300);
4655         }
4656
4657         #[test]
4658         fn total_empty_route_no_panic() {
4659                 // In an earlier version of `Route::get_total_fees` and `Route::get_total_amount`, they
4660                 // would both panic if the route was completely empty. We test to ensure they return 0
4661                 // here, even though its somewhat nonsensical as a route.
4662                 let route = Route { paths: Vec::new(), payee: None };
4663
4664                 assert_eq!(route.get_total_fees(), 0);
4665                 assert_eq!(route.get_total_amount(), 0);
4666         }
4667
4668         #[cfg(not(feature = "no-std"))]
4669         pub(super) fn random_init_seed() -> u64 {
4670                 // Because the default HashMap in std pulls OS randomness, we can use it as a (bad) RNG.
4671                 use core::hash::{BuildHasher, Hasher};
4672                 let seed = std::collections::hash_map::RandomState::new().build_hasher().finish();
4673                 println!("Using seed of {}", seed);
4674                 seed
4675         }
4676         #[cfg(not(feature = "no-std"))]
4677         use util::ser::Readable;
4678
4679         #[test]
4680         #[cfg(not(feature = "no-std"))]
4681         fn generate_routes() {
4682                 let mut d = match super::test_utils::get_route_file() {
4683                         Ok(f) => f,
4684                         Err(e) => {
4685                                 eprintln!("{}", e);
4686                                 return;
4687                         },
4688                 };
4689                 let graph = NetworkGraph::read(&mut d).unwrap();
4690                 let scorer = Scorer::new(0);
4691
4692                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
4693                 let mut seed = random_init_seed() as usize;
4694                 let nodes = graph.read_only().nodes().clone();
4695                 'load_endpoints: for _ in 0..10 {
4696                         loop {
4697                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4698                                 let src = &PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4699                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4700                                 let dst = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4701                                 let payee = Payee::new(dst);
4702                                 let amt = seed as u64 % 200_000_000;
4703                                 if get_route(src, &payee, &graph, None, amt, 42, &test_utils::TestLogger::new(), &scorer).is_ok() {
4704                                         continue 'load_endpoints;
4705                                 }
4706                         }
4707                 }
4708         }
4709
4710         #[test]
4711         #[cfg(not(feature = "no-std"))]
4712         fn generate_routes_mpp() {
4713                 let mut d = match super::test_utils::get_route_file() {
4714                         Ok(f) => f,
4715                         Err(e) => {
4716                                 eprintln!("{}", e);
4717                                 return;
4718                         },
4719                 };
4720                 let graph = NetworkGraph::read(&mut d).unwrap();
4721                 let scorer = Scorer::new(0);
4722
4723                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
4724                 let mut seed = random_init_seed() as usize;
4725                 let nodes = graph.read_only().nodes().clone();
4726                 'load_endpoints: for _ in 0..10 {
4727                         loop {
4728                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4729                                 let src = &PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4730                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4731                                 let dst = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4732                                 let payee = Payee::new(dst).with_features(InvoiceFeatures::known());
4733                                 let amt = seed as u64 % 200_000_000;
4734                                 if get_route(src, &payee, &graph, None, amt, 42, &test_utils::TestLogger::new(), &scorer).is_ok() {
4735                                         continue 'load_endpoints;
4736                                 }
4737                         }
4738                 }
4739         }
4740 }
4741
4742 #[cfg(all(test, not(feature = "no-std")))]
4743 pub(crate) mod test_utils {
4744         use std::fs::File;
4745         /// Tries to open a network graph file, or panics with a URL to fetch it.
4746         pub(crate) fn get_route_file() -> Result<std::fs::File, &'static str> {
4747                 let res = File::open("net_graph-2021-05-31.bin") // By default we're run in RL/lightning
4748                         .or_else(|_| File::open("lightning/net_graph-2021-05-31.bin")) // We may be run manually in RL/
4749                         .or_else(|_| { // Fall back to guessing based on the binary location
4750                                 // path is likely something like .../rust-lightning/target/debug/deps/lightning-...
4751                                 let mut path = std::env::current_exe().unwrap();
4752                                 path.pop(); // lightning-...
4753                                 path.pop(); // deps
4754                                 path.pop(); // debug
4755                                 path.pop(); // target
4756                                 path.push("lightning");
4757                                 path.push("net_graph-2021-05-31.bin");
4758                                 eprintln!("{}", path.to_str().unwrap());
4759                                 File::open(path)
4760                         })
4761                 .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");
4762                 #[cfg(require_route_graph_test)]
4763                 return Ok(res.unwrap());
4764                 #[cfg(not(require_route_graph_test))]
4765                 return res;
4766         }
4767 }
4768
4769 #[cfg(all(test, feature = "unstable", not(feature = "no-std")))]
4770 mod benches {
4771         use super::*;
4772         use routing::scorer::Scorer;
4773         use util::logger::{Logger, Record};
4774
4775         use test::Bencher;
4776
4777         struct DummyLogger {}
4778         impl Logger for DummyLogger {
4779                 fn log(&self, _record: &Record) {}
4780         }
4781
4782         #[bench]
4783         fn generate_routes(bench: &mut Bencher) {
4784                 let mut d = test_utils::get_route_file().unwrap();
4785                 let graph = NetworkGraph::read(&mut d).unwrap();
4786                 let nodes = graph.read_only().nodes().clone();
4787                 let scorer = Scorer::new(0);
4788
4789                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
4790                 let mut path_endpoints = Vec::new();
4791                 let mut seed: usize = 0xdeadbeef;
4792                 'load_endpoints: for _ in 0..100 {
4793                         loop {
4794                                 seed *= 0xdeadbeef;
4795                                 let src = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4796                                 seed *= 0xdeadbeef;
4797                                 let dst = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4798                                 let payee = Payee::new(dst);
4799                                 let amt = seed as u64 % 1_000_000;
4800                                 if get_route(&src, &payee, &graph, None, amt, 42, &DummyLogger{}, &scorer).is_ok() {
4801                                         path_endpoints.push((src, dst, amt));
4802                                         continue 'load_endpoints;
4803                                 }
4804                         }
4805                 }
4806
4807                 // ...then benchmark finding paths between the nodes we learned.
4808                 let mut idx = 0;
4809                 bench.iter(|| {
4810                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
4811                         let payee = Payee::new(dst);
4812                         assert!(get_route(&src, &payee, &graph, None, amt, 42, &DummyLogger{}, &scorer).is_ok());
4813                         idx += 1;
4814                 });
4815         }
4816
4817         #[bench]
4818         fn generate_mpp_routes(bench: &mut Bencher) {
4819                 let mut d = test_utils::get_route_file().unwrap();
4820                 let graph = NetworkGraph::read(&mut d).unwrap();
4821                 let nodes = graph.read_only().nodes().clone();
4822                 let scorer = Scorer::new(0);
4823
4824                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
4825                 let mut path_endpoints = Vec::new();
4826                 let mut seed: usize = 0xdeadbeef;
4827                 'load_endpoints: for _ in 0..100 {
4828                         loop {
4829                                 seed *= 0xdeadbeef;
4830                                 let src = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4831                                 seed *= 0xdeadbeef;
4832                                 let dst = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4833                                 let payee = Payee::new(dst).with_features(InvoiceFeatures::known());
4834                                 let amt = seed as u64 % 1_000_000;
4835                                 if get_route(&src, &payee, &graph, None, amt, 42, &DummyLogger{}, &scorer).is_ok() {
4836                                         path_endpoints.push((src, dst, amt));
4837                                         continue 'load_endpoints;
4838                                 }
4839                         }
4840                 }
4841
4842                 // ...then benchmark finding paths between the nodes we learned.
4843                 let mut idx = 0;
4844                 bench.iter(|| {
4845                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
4846                         let payee = Payee::new(dst).with_features(InvoiceFeatures::known());
4847                         assert!(get_route(&src, &payee, &graph, None, amt, 42, &DummyLogger{}, &scorer).is_ok());
4848                         idx += 1;
4849                 });
4850         }
4851 }