_ 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 }
  74
  75 impl Route {
  76         /// Returns the total amount of fees paid on this [`Route`].
  77         ///
  78         /// This doesn't include any extra payment made to the recipient, which can happen in excess of
  79         /// the amount passed to [`get_route`]'s `final_value_msat`.
  80         pub fn get_total_fees(&self) -> u64 {
  81                 // Do not count last hop of each path since that's the full value of the payment
  82                 return self.paths.iter()
  83                         .flat_map(|path| path.split_last().map(|(_, path_prefix)| path_prefix).unwrap_or(&[]))
  84                         .map(|hop| &hop.fee_msat)
  85                         .sum();
  86         }
  87
  88         /// Returns the total amount paid on this [`Route`], excluding the fees.
  89         pub fn get_total_amount(&self) -> u64 {
  90                 return self.paths.iter()
  91                         .map(|path| path.split_last().map(|(hop, _)| hop.fee_msat).unwrap_or(0))
  92                         .sum();
  93         }
  94 }
  95
  96 const SERIALIZATION_VERSION: u8 = 1;
  97 const MIN_SERIALIZATION_VERSION: u8 = 1;
  98
  99 impl Writeable for Route {
 100         fn write<W: ::util::ser::Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 101                 write_ver_prefix!(writer, SERIALIZATION_VERSION, MIN_SERIALIZATION_VERSION);
 102                 (self.paths.len() as u64).write(writer)?;
 103                 for hops in self.paths.iter() {
 104                         (hops.len() as u8).write(writer)?;
 105                         for hop in hops.iter() {
 106                                 hop.write(writer)?;
 107                         }
 108                 }
 109                 write_tlv_fields!(writer, {});
 110                 Ok(())
 111         }
 112 }
 113
 114 impl Readable for Route {
 115         fn read<R: io::Read>(reader: &mut R) -> Result<Route, DecodeError> {
 116                 let _ver = read_ver_prefix!(reader, SERIALIZATION_VERSION);
 117                 let path_count: u64 = Readable::read(reader)?;
 118                 let mut paths = Vec::with_capacity(cmp::min(path_count, 128) as usize);
 119                 for _ in 0..path_count {
 120                         let hop_count: u8 = Readable::read(reader)?;
 121                         let mut hops = Vec::with_capacity(hop_count as usize);
 122                         for _ in 0..hop_count {
 123                                 hops.push(Readable::read(reader)?);
 124                         }
 125                         paths.push(hops);
 126                 }
 127                 read_tlv_fields!(reader, {});
 128                 Ok(Route { paths })
 129         }
 130 }
 131
 132 /// A list of hops along a payment path terminating with a channel to the recipient.
 133 #[derive(Clone, Debug, Hash, Eq, PartialEq)]
 134 pub struct RouteHint(pub Vec<RouteHintHop>);
 135
 136 /// A channel descriptor for a hop along a payment path.
 137 #[derive(Clone, Debug, Hash, Eq, PartialEq)]
 138 pub struct RouteHintHop {
 139         /// The node_id of the non-target end of the route
 140         pub src_node_id: PublicKey,
 141         /// The short_channel_id of this channel
 142         pub short_channel_id: u64,
 143         /// The fees which must be paid to use this channel
 144         pub fees: RoutingFees,
 145         /// The difference in CLTV values between this node and the next node.
 146         pub cltv_expiry_delta: u16,
 147         /// The minimum value, in msat, which must be relayed to the next hop.
 148         pub htlc_minimum_msat: Option<u64>,
 149         /// The maximum value in msat available for routing with a single HTLC.
 150         pub htlc_maximum_msat: Option<u64>,
 151 }
 152
 153 #[derive(Eq, PartialEq)]
 154 struct RouteGraphNode {
 155         node_id: NodeId,
 156         lowest_fee_to_peer_through_node: u64,
 157         lowest_fee_to_node: u64,
 158         // The maximum value a yet-to-be-constructed payment path might flow through this node.
 159         // This value is upper-bounded by us by:
 160         // - how much is needed for a path being constructed
 161         // - how much value can channels following this node (up to the destination) can contribute,
 162         //   considering their capacity and fees
 163         value_contribution_msat: u64,
 164         /// The effective htlc_minimum_msat at this hop. If a later hop on the path had a higher HTLC
 165         /// minimum, we use it, plus the fees required at each earlier hop to meet it.
 166         path_htlc_minimum_msat: u64,
 167         /// All penalties incurred from this hop on the way to the destination, as calculated using
 168         /// channel scoring.
 169         path_penalty_msat: u64,
 170 }
 171
 172 impl cmp::Ord for RouteGraphNode {
 173         fn cmp(&self, other: &RouteGraphNode) -> cmp::Ordering {
 174                 let other_score = cmp::max(other.lowest_fee_to_peer_through_node, other.path_htlc_minimum_msat)
 175                         .checked_add(other.path_penalty_msat)
 176                         .unwrap_or_else(|| u64::max_value());
 177                 let self_score = cmp::max(self.lowest_fee_to_peer_through_node, self.path_htlc_minimum_msat)
 178                         .checked_add(self.path_penalty_msat)
 179                         .unwrap_or_else(|| u64::max_value());
 180                 other_score.cmp(&self_score).then_with(|| other.node_id.cmp(&self.node_id))
 181         }
 182 }
 183
 184 impl cmp::PartialOrd for RouteGraphNode {
 185         fn partial_cmp(&self, other: &RouteGraphNode) -> Option<cmp::Ordering> {
 186                 Some(self.cmp(other))
 187         }
 188 }
 189
 190 struct DummyDirectionalChannelInfo {
 191         cltv_expiry_delta: u32,
 192         htlc_minimum_msat: u64,
 193         htlc_maximum_msat: Option<u64>,
 194         fees: RoutingFees,
 195 }
 196
 197 /// It's useful to keep track of the hops associated with the fees required to use them,
 198 /// so that we can choose cheaper paths (as per Dijkstra's algorithm).
 199 /// Fee values should be updated only in the context of the whole path, see update_value_and_recompute_fees.
 200 /// These fee values are useful to choose hops as we traverse the graph "payee-to-payer".
 201 #[derive(Clone, Debug)]
 202 struct PathBuildingHop<'a> {
 203         // The RouteHintHop fields which will eventually be used if this hop is used in a final Route.
 204         // Note that node_features is calculated separately after our initial graph walk.
 205         node_id: NodeId,
 206         short_channel_id: u64,
 207         channel_features: &'a ChannelFeatures,
 208         fee_msat: u64,
 209         cltv_expiry_delta: u32,
 210
 211         /// Minimal fees required to route to the source node of the current hop via any of its inbound channels.
 212         src_lowest_inbound_fees: RoutingFees,
 213         /// Fees of the channel used in this hop.
 214         channel_fees: RoutingFees,
 215         /// All the fees paid *after* this channel on the way to the destination
 216         next_hops_fee_msat: u64,
 217         /// Fee paid for the use of the current channel (see channel_fees).
 218         /// The value will be actually deducted from the counterparty balance on the previous link.
 219         hop_use_fee_msat: u64,
 220         /// Used to compare channels when choosing the for routing.
 221         /// Includes paying for the use of a hop and the following hops, as well as
 222         /// an estimated cost of reaching this hop.
 223         /// Might get stale when fees are recomputed. Primarily for internal use.
 224         total_fee_msat: u64,
 225         /// This is useful for update_value_and_recompute_fees to make sure
 226         /// we don't fall below the minimum. Should not be updated manually and
 227         /// generally should not be accessed.
 228         htlc_minimum_msat: u64,
 229         /// A mirror of the same field in RouteGraphNode. Note that this is only used during the graph
 230         /// walk and may be invalid thereafter.
 231         path_htlc_minimum_msat: u64,
 232         /// All penalties incurred from this channel on the way to the destination, as calculated using
 233         /// channel scoring.
 234         path_penalty_msat: u64,
 235         /// If we've already processed a node as the best node, we shouldn't process it again. Normally
 236         /// we'd just ignore it if we did as all channels would have a higher new fee, but because we
 237         /// may decrease the amounts in use as we walk the graph, the actual calculated fee may
 238         /// decrease as well. Thus, we have to explicitly track which nodes have been processed and
 239         /// avoid processing them again.
 240         was_processed: bool,
 241         #[cfg(any(test, feature = "fuzztarget"))]
 242         // In tests, we apply further sanity checks on cases where we skip nodes we already processed
 243         // to ensure it is specifically in cases where the fee has gone down because of a decrease in
 244         // value_contribution_msat, which requires tracking it here. See comments below where it is
 245         // used for more info.
 246         value_contribution_msat: u64,
 247 }
 248
 249 // Instantiated with a list of hops with correct data in them collected during path finding,
 250 // an instance of this struct should be further modified only via given methods.
 251 #[derive(Clone)]
 252 struct PaymentPath<'a> {
 253         hops: Vec<(PathBuildingHop<'a>, NodeFeatures)>,
 254 }
 255
 256 impl<'a> PaymentPath<'a> {
 257         // TODO: Add a value_msat field to PaymentPath and use it instead of this function.
 258         fn get_value_msat(&self) -> u64 {
 259                 self.hops.last().unwrap().0.fee_msat
 260         }
 261
 262         fn get_total_fee_paid_msat(&self) -> u64 {
 263                 if self.hops.len() < 1 {
 264                         return 0;
 265                 }
 266                 let mut result = 0;
 267                 // Can't use next_hops_fee_msat because it gets outdated.
 268                 for (i, (hop, _)) in self.hops.iter().enumerate() {
 269                         if i != self.hops.len() - 1 {
 270                                 result += hop.fee_msat;
 271                         }
 272                 }
 273                 return result;
 274         }
 275
 276         // If the amount transferred by the path is updated, the fees should be adjusted. Any other way
 277         // to change fees may result in an inconsistency.
 278         //
 279         // Sometimes we call this function right after constructing a path which is inconsistent in
 280         // that it the value being transferred has decreased while we were doing path finding, leading
 281         // to the fees being paid not lining up with the actual limits.
 282         //
 283         // Note that this function is not aware of the available_liquidity limit, and thus does not
 284         // support increasing the value being transferred.
 285         fn update_value_and_recompute_fees(&mut self, value_msat: u64) {
 286                 assert!(value_msat <= self.hops.last().unwrap().0.fee_msat);
 287
 288                 let mut total_fee_paid_msat = 0 as u64;
 289                 for i in (0..self.hops.len()).rev() {
 290                         let last_hop = i == self.hops.len() - 1;
 291
 292                         // For non-last-hop, this value will represent the fees paid on the current hop. It
 293                         // will consist of the fees for the use of the next hop, and extra fees to match
 294                         // htlc_minimum_msat of the current channel. Last hop is handled separately.
 295                         let mut cur_hop_fees_msat = 0;
 296                         if !last_hop {
 297                                 cur_hop_fees_msat = self.hops.get(i + 1).unwrap().0.hop_use_fee_msat;
 298                         }
 299
 300                         let mut cur_hop = &mut self.hops.get_mut(i).unwrap().0;
 301                         cur_hop.next_hops_fee_msat = total_fee_paid_msat;
 302                         // Overpay in fees if we can't save these funds due to htlc_minimum_msat.
 303                         // We try to account for htlc_minimum_msat in scoring (add_entry!), so that nodes don't
 304                         // set it too high just to maliciously take more fees by exploiting this
 305                         // match htlc_minimum_msat logic.
 306                         let mut cur_hop_transferred_amount_msat = total_fee_paid_msat + value_msat;
 307                         if let Some(extra_fees_msat) = cur_hop.htlc_minimum_msat.checked_sub(cur_hop_transferred_amount_msat) {
 308                                 // Note that there is a risk that *previous hops* (those closer to us, as we go
 309                                 // payee->our_node here) would exceed their htlc_maximum_msat or available balance.
 310                                 //
 311                                 // This might make us end up with a broken route, although this should be super-rare
 312                                 // in practice, both because of how healthy channels look like, and how we pick
 313                                 // channels in add_entry.
 314                                 // Also, this can't be exploited more heavily than *announce a free path and fail
 315                                 // all payments*.
 316                                 cur_hop_transferred_amount_msat += extra_fees_msat;
 317                                 total_fee_paid_msat += extra_fees_msat;
 318                                 cur_hop_fees_msat += extra_fees_msat;
 319                         }
 320
 321                         if last_hop {
 322                                 // Final hop is a special case: it usually has just value_msat (by design), but also
 323                                 // it still could overpay for the htlc_minimum_msat.
 324                                 cur_hop.fee_msat = cur_hop_transferred_amount_msat;
 325                         } else {
 326                                 // Propagate updated fees for the use of the channels to one hop back, where they
 327                                 // will be actually paid (fee_msat). The last hop is handled above separately.
 328                                 cur_hop.fee_msat = cur_hop_fees_msat;
 329                         }
 330
 331                         // Fee for the use of the current hop which will be deducted on the previous hop.
 332                         // Irrelevant for the first hop, as it doesn't have the previous hop, and the use of
 333                         // this channel is free for us.
 334                         if i != 0 {
 335                                 if let Some(new_fee) = compute_fees(cur_hop_transferred_amount_msat, cur_hop.channel_fees) {
 336                                         cur_hop.hop_use_fee_msat = new_fee;
 337                                         total_fee_paid_msat += new_fee;
 338                                 } else {
 339                                         // It should not be possible because this function is called only to reduce the
 340                                         // value. In that case, compute_fee was already called with the same fees for
 341                                         // larger amount and there was no overflow.
 342                                         unreachable!();
 343                                 }
 344                         }
 345                 }
 346         }
 347 }
 348
 349 fn compute_fees(amount_msat: u64, channel_fees: RoutingFees) -> Option<u64> {
 350         let proportional_fee_millions =
 351                 amount_msat.checked_mul(channel_fees.proportional_millionths as u64);
 352         if let Some(new_fee) = proportional_fee_millions.and_then(|part| {
 353                         (channel_fees.base_msat as u64).checked_add(part / 1_000_000) }) {
 354
 355                 Some(new_fee)
 356         } else {
 357                 // This function may be (indirectly) called without any verification,
 358                 // with channel_fees provided by a caller. We should handle it gracefully.
 359                 None
 360         }
 361 }
 362
 363 /// Gets a keysend route from us (payer) to the given target node (payee). This is needed because
 364 /// keysend payments do not have an invoice from which to pull the payee's supported features, which
 365 /// makes it tricky to otherwise supply the `payee_features` parameter of `get_route`.
 366 pub fn get_keysend_route<L: Deref, S: routing::Score>(
 367         our_node_pubkey: &PublicKey, network: &NetworkGraph, payee: &PublicKey,
 368         first_hops: Option<&[&ChannelDetails]>, last_hops: &[&RouteHint], final_value_msat: u64,
 369         final_cltv: u32, logger: L, scorer: &S
 370 ) -> Result<Route, LightningError>
 371 where L::Target: Logger {
 372         let invoice_features = InvoiceFeatures::for_keysend();
 373         get_route(
 374                 our_node_pubkey, network, payee, Some(invoice_features), first_hops, last_hops,
 375                 final_value_msat, final_cltv, logger, scorer
 376         )
 377 }
 378
 379 /// Gets a route from us (payer) to the given target node (payee).
 380 ///
 381 /// If the payee provided features in their invoice, they should be provided via payee_features.
 382 /// Without this, MPP will only be used if the payee's features are available in the network graph.
 383 ///
 384 /// Private routing paths between a public node and the target may be included in `last_hops`.
 385 /// Currently, only the last hop in each path is considered.
 386 ///
 387 /// If some channels aren't announced, it may be useful to fill in a first_hops with the
 388 /// results from a local ChannelManager::list_usable_channels() call. If it is filled in, our
 389 /// view of our local channels (from net_graph_msg_handler) will be ignored, and only those
 390 /// in first_hops will be used.
 391 ///
 392 /// Panics if first_hops contains channels without short_channel_ids
 393 /// (ChannelManager::list_usable_channels will never include such channels).
 394 ///
 395 /// The fees on channels from us to next-hops are ignored (as they are assumed to all be
 396 /// equal), however the enabled/disabled bit on such channels as well as the
 397 /// htlc_minimum_msat/htlc_maximum_msat *are* checked as they may change based on the receiving node.
 398 pub fn get_route<L: Deref, S: routing::Score>(
 399         our_node_pubkey: &PublicKey, network: &NetworkGraph, payee: &PublicKey,
 400         payee_features: Option<InvoiceFeatures>, first_hops: Option<&[&ChannelDetails]>,
 401         last_hops: &[&RouteHint], final_value_msat: u64, final_cltv: u32, logger: L, scorer: &S
 402 ) -> Result<Route, LightningError>
 403 where L::Target: Logger {
 404         let payee_node_id = NodeId::from_pubkey(&payee);
 405         let our_node_id = NodeId::from_pubkey(&our_node_pubkey);
 406
 407         if payee_node_id == our_node_id {
 408                 return Err(LightningError{err: "Cannot generate a route to ourselves".to_owned(), action: ErrorAction::IgnoreError});
 409         }
 410
 411         if final_value_msat > MAX_VALUE_MSAT {
 412                 return Err(LightningError{err: "Cannot generate a route of more value than all existing satoshis".to_owned(), action: ErrorAction::IgnoreError});
 413         }
 414
 415         if final_value_msat == 0 {
 416                 return Err(LightningError{err: "Cannot send a payment of 0 msat".to_owned(), action: ErrorAction::IgnoreError});
 417         }
 418
 419         for route in last_hops.iter() {
 420                 for hop in &route.0 {
 421                         if hop.src_node_id == *payee {
 422                                 return Err(LightningError{err: "Last hop cannot have a payee as a source.".to_owned(), action: ErrorAction::IgnoreError});
 423                         }
 424                 }
 425         }
 426
 427         // The general routing idea is the following:
 428         // 1. Fill first/last hops communicated by the caller.
 429         // 2. Attempt to construct a path from payer to payee for transferring
 430         //    any ~sufficient (described later) value.
 431         //    If succeed, remember which channels were used and how much liquidity they have available,
 432         //    so that future paths don't rely on the same liquidity.
 433         // 3. Prooceed to the next step if:
 434         //    - we hit the recommended target value;
 435         //    - OR if we could not construct a new path. Any next attempt will fail too.
 436         //    Otherwise, repeat step 2.
 437         // 4. See if we managed to collect paths which aggregately are able to transfer target value
 438         //    (not recommended value). If yes, proceed. If not, fail routing.
 439         // 5. Randomly combine paths into routes having enough to fulfill the payment. (TODO: knapsack)
 440         // 6. Of all the found paths, select only those with the lowest total fee.
 441         // 7. The last path in every selected route is likely to be more than we need.
 442         //    Reduce its value-to-transfer and recompute fees.
 443         // 8. Choose the best route by the lowest total fee.
 444
 445         // As for the actual search algorithm,
 446         // we do a payee-to-payer pseudo-Dijkstra's sorting by each node's distance from the payee
 447         // plus the minimum per-HTLC fee to get from it to another node (aka "shitty pseudo-A*").
 448         //
 449         // We are not a faithful Dijkstra's implementation because we can change values which impact
 450         // earlier nodes while processing later nodes. Specifically, if we reach a channel with a lower
 451         // liquidity limit (via htlc_maximum_msat, on-chain capacity or assumed liquidity limits) then
 452         // the value we are currently attempting to send over a path, we simply reduce the value being
 453         // sent along the path for any hops after that channel. This may imply that later fees (which
 454         // we've already tabulated) are lower because a smaller value is passing through the channels
 455         // (and the proportional fee is thus lower). There isn't a trivial way to recalculate the
 456         // channels which were selected earlier (and which may still be used for other paths without a
 457         // lower liquidity limit), so we simply accept that some liquidity-limited paths may be
 458         // de-preferenced.
 459         //
 460         // One potentially problematic case for this algorithm would be if there are many
 461         // liquidity-limited paths which are liquidity-limited near the destination (ie early in our
 462         // graph walking), we may never find a path which is not liquidity-limited and has lower
 463         // proportional fee (and only lower absolute fee when considering the ultimate value sent).
 464         // Because we only consider paths with at least 5% of the total value being sent, the damage
 465         // from such a case should be limited, however this could be further reduced in the future by
 466         // calculating fees on the amount we wish to route over a path, ie ignoring the liquidity
 467         // limits for the purposes of fee calculation.
 468         //
 469         // Alternatively, we could store more detailed path information in the heap (targets, below)
 470         // and index the best-path map (dist, below) by node *and* HTLC limits, however that would blow
 471         // up the runtime significantly both algorithmically (as we'd traverse nodes multiple times)
 472         // and practically (as we would need to store dynamically-allocated path information in heap
 473         // objects, increasing malloc traffic and indirect memory access significantly). Further, the
 474         // results of such an algorithm would likely be biased towards lower-value paths.
 475         //
 476         // Further, we could return to a faithful Dijkstra's algorithm by rejecting paths with limits
 477         // outside of our current search value, running a path search more times to gather candidate
 478         // paths at different values. While this may be acceptable, further path searches may increase
 479         // runtime for little gain. Specifically, the current algorithm rather efficiently explores the
 480         // graph for candidate paths, calculating the maximum value which can realistically be sent at
 481         // the same time, remaining generic across different payment values.
 482         //
 483         // TODO: There are a few tweaks we could do, including possibly pre-calculating more stuff
 484         // to use as the A* heuristic beyond just the cost to get one node further than the current
 485         // one.
 486
 487         let network_graph = network.read_only();
 488         let network_channels = network_graph.channels();
 489         let network_nodes = network_graph.nodes();
 490         let dummy_directional_info = DummyDirectionalChannelInfo { // used for first_hops routes
 491                 cltv_expiry_delta: 0,
 492                 htlc_minimum_msat: 0,
 493                 htlc_maximum_msat: None,
 494                 fees: RoutingFees {
 495                         base_msat: 0,
 496                         proportional_millionths: 0,
 497                 }
 498         };
 499
 500         // Allow MPP only if we have a features set from somewhere that indicates the payee supports
 501         // it. If the payee supports it they're supposed to include it in the invoice, so that should
 502         // work reliably.
 503         let allow_mpp = if let Some(features) = &payee_features {
 504                 features.supports_basic_mpp()
 505         } else if let Some(node) = network_nodes.get(&payee_node_id) {
 506                 if let Some(node_info) = node.announcement_info.as_ref() {
 507                         node_info.features.supports_basic_mpp()
 508                 } else { false }
 509         } else { false };
 510         log_trace!(logger, "Searching for a route from payer {} to payee {} {} MPP", our_node_pubkey, payee,
 511                 if allow_mpp { "with" } else { "without" });
 512
 513         // Step (1).
 514         // Prepare the data we'll use for payee-to-payer search by
 515         // inserting first hops suggested by the caller as targets.
 516         // Our search will then attempt to reach them while traversing from the payee node.
 517         let mut first_hop_targets: HashMap<_, Vec<(_, ChannelFeatures, _, NodeFeatures)>> =
 518                 HashMap::with_capacity(if first_hops.is_some() { first_hops.as_ref().unwrap().len() } else { 0 });
 519         if let Some(hops) = first_hops {
 520                 for chan in hops {
 521                         let short_channel_id = chan.short_channel_id.expect("first_hops should be filled in with usable channels, not pending ones");
 522                         if chan.counterparty.node_id == *our_node_pubkey {
 523                                 return Err(LightningError{err: "First hop cannot have our_node_pubkey as a destination.".to_owned(), action: ErrorAction::IgnoreError});
 524                         }
 525                         first_hop_targets.entry(NodeId::from_pubkey(&chan.counterparty.node_id)).or_insert(Vec::new())
 526                                 .push((short_channel_id, chan.counterparty.features.to_context(), chan.outbound_capacity_msat, chan.counterparty.features.to_context()));
 527                 }
 528                 if first_hop_targets.is_empty() {
 529                         return Err(LightningError{err: "Cannot route when there are no outbound routes away from us".to_owned(), action: ErrorAction::IgnoreError});
 530                 }
 531         }
 532
 533         let empty_channel_features = ChannelFeatures::empty();
 534
 535         // The main heap containing all candidate next-hops sorted by their score (max(A* fee,
 536         // htlc_minimum)). Ideally this would be a heap which allowed cheap score reduction instead of
 537         // adding duplicate entries when we find a better path to a given node.
 538         let mut targets = BinaryHeap::new();
 539
 540         // Map from node_id to information about the best current path to that node, including feerate
 541         // information.
 542         let mut dist = HashMap::with_capacity(network_nodes.len());
 543
 544         // During routing, if we ignore a path due to an htlc_minimum_msat limit, we set this,
 545         // indicating that we may wish to try again with a higher value, potentially paying to meet an
 546         // htlc_minimum with extra fees while still finding a cheaper path.
 547         let mut hit_minimum_limit;
 548
 549         // When arranging a route, we select multiple paths so that we can make a multi-path payment.
 550         // We start with a path_value of the exact amount we want, and if that generates a route we may
 551         // return it immediately. Otherwise, we don't stop searching for paths until we have 3x the
 552         // amount we want in total across paths, selecting the best subset at the end.
 553         const ROUTE_CAPACITY_PROVISION_FACTOR: u64 = 3;
 554         let recommended_value_msat = final_value_msat * ROUTE_CAPACITY_PROVISION_FACTOR as u64;
 555         let mut path_value_msat = final_value_msat;
 556
 557         // We don't want multiple paths (as per MPP) share liquidity of the same channels.
 558         // This map allows paths to be aware of the channel use by other paths in the same call.
 559         // This would help to make a better path finding decisions and not "overbook" channels.
 560         // It is unaware of the directions (except for `outbound_capacity_msat` in `first_hops`).
 561         let mut bookkeeped_channels_liquidity_available_msat = HashMap::with_capacity(network_nodes.len());
 562
 563         // Keeping track of how much value we already collected across other paths. Helps to decide:
 564         // - how much a new path should be transferring (upper bound);
 565         // - whether a channel should be disregarded because
 566         //   it's available liquidity is too small comparing to how much more we need to collect;
 567         // - when we want to stop looking for new paths.
 568         let mut already_collected_value_msat = 0;
 569
 570         log_trace!(logger, "Building path from {} (payee) to {} (us/payer) for value {} msat.", payee, our_node_pubkey, final_value_msat);
 571
 572         macro_rules! add_entry {
 573                 // Adds entry which goes from $src_node_id to $dest_node_id
 574                 // over the channel with id $chan_id with fees described in
 575                 // $directional_info.
 576                 // $next_hops_fee_msat represents the fees paid for using all the channel *after* this one,
 577                 // since that value has to be transferred over this channel.
 578                 // Returns whether this channel caused an update to `targets`.
 579                 ( $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,
 580                    $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr, $next_hops_path_penalty_msat: expr ) => { {
 581                         // We "return" whether we updated the path at the end, via this:
 582                         let mut did_add_update_path_to_src_node = false;
 583                         // Channels to self should not be used. This is more of belt-and-suspenders, because in
 584                         // practice these cases should be caught earlier:
 585                         // - for regular channels at channel announcement (TODO)
 586                         // - for first and last hops early in get_route
 587                         if $src_node_id != $dest_node_id.clone() {
 588                                 let available_liquidity_msat = bookkeeped_channels_liquidity_available_msat.entry($chan_id.clone()).or_insert_with(|| {
 589                                         let mut initial_liquidity_available_msat = None;
 590                                         if let Some(capacity_sats) = $capacity_sats {
 591                                                 initial_liquidity_available_msat = Some(capacity_sats * 1000);
 592                                         }
 593
 594                                         if let Some(htlc_maximum_msat) = $directional_info.htlc_maximum_msat {
 595                                                 if let Some(available_msat) = initial_liquidity_available_msat {
 596                                                         initial_liquidity_available_msat = Some(cmp::min(available_msat, htlc_maximum_msat));
 597                                                 } else {
 598                                                         initial_liquidity_available_msat = Some(htlc_maximum_msat);
 599                                                 }
 600                                         }
 601
 602                                         match initial_liquidity_available_msat {
 603                                                 Some(available_msat) => available_msat,
 604                                                 // We assume channels with unknown balance have
 605                                                 // a capacity of 0.0025 BTC (or 250_000 sats).
 606                                                 None => 250_000 * 1000
 607                                         }
 608                                 });
 609
 610                                 // It is tricky to substract $next_hops_fee_msat from available liquidity here.
 611                                 // It may be misleading because we might later choose to reduce the value transferred
 612                                 // over these channels, and the channel which was insufficient might become sufficient.
 613                                 // Worst case: we drop a good channel here because it can't cover the high following
 614                                 // fees caused by one expensive channel, but then this channel could have been used
 615                                 // if the amount being transferred over this path is lower.
 616                                 // We do this for now, but this is a subject for removal.
 617                                 if let Some(available_value_contribution_msat) = available_liquidity_msat.checked_sub($next_hops_fee_msat) {
 618
 619                                         // Routing Fragmentation Mitigation heuristic:
 620                                         //
 621                                         // Routing fragmentation across many payment paths increases the overall routing
 622                                         // fees as you have irreducible routing fees per-link used (`fee_base_msat`).
 623                                         // Taking too many smaller paths also increases the chance of payment failure.
 624                                         // Thus to avoid this effect, we require from our collected links to provide
 625                                         // at least a minimal contribution to the recommended value yet-to-be-fulfilled.
 626                                         //
 627                                         // This requirement is currently 5% of the remaining-to-be-collected value.
 628                                         // This means as we successfully advance in our collection,
 629                                         // the absolute liquidity contribution is lowered,
 630                                         // thus increasing the number of potential channels to be selected.
 631
 632                                         // Derive the minimal liquidity contribution with a ratio of 20 (5%, rounded up)
 633                                         // or 100% if we're not allowed to do multipath payments.
 634                                         let minimal_value_contribution_msat: u64 = if allow_mpp {
 635                                                 (recommended_value_msat - already_collected_value_msat + 19) / 20
 636                                         } else {
 637                                                 final_value_msat
 638                                         };
 639                                         // Verify the liquidity offered by this channel complies to the minimal contribution.
 640                                         let contributes_sufficient_value = available_value_contribution_msat >= minimal_value_contribution_msat;
 641
 642                                         let value_contribution_msat = cmp::min(available_value_contribution_msat, $next_hops_value_contribution);
 643                                         // Includes paying fees for the use of the following channels.
 644                                         let amount_to_transfer_over_msat: u64 = match value_contribution_msat.checked_add($next_hops_fee_msat) {
 645                                                 Some(result) => result,
 646                                                 // Can't overflow due to how the values were computed right above.
 647                                                 None => unreachable!(),
 648                                         };
 649                                         #[allow(unused_comparisons)] // $next_hops_path_htlc_minimum_msat is 0 in some calls so rustc complains
 650                                         let over_path_minimum_msat = amount_to_transfer_over_msat >= $directional_info.htlc_minimum_msat &&
 651                                                 amount_to_transfer_over_msat >= $next_hops_path_htlc_minimum_msat;
 652
 653                                         // If HTLC minimum is larger than the amount we're going to transfer, we shouldn't
 654                                         // bother considering this channel.
 655                                         // Since we're choosing amount_to_transfer_over_msat as maximum possible, it can
 656                                         // be only reduced later (not increased), so this channel should just be skipped
 657                                         // as not sufficient.
 658                                         if !over_path_minimum_msat {
 659                                                 hit_minimum_limit = true;
 660                                         } else if contributes_sufficient_value {
 661                                                 // Note that low contribution here (limited by available_liquidity_msat)
 662                                                 // might violate htlc_minimum_msat on the hops which are next along the
 663                                                 // payment path (upstream to the payee). To avoid that, we recompute path
 664                                                 // path fees knowing the final path contribution after constructing it.
 665                                                 let path_htlc_minimum_msat = compute_fees($next_hops_path_htlc_minimum_msat, $directional_info.fees)
 666                                                         .and_then(|fee_msat| fee_msat.checked_add($next_hops_path_htlc_minimum_msat))
 667                                                         .map(|fee_msat| cmp::max(fee_msat, $directional_info.htlc_minimum_msat))
 668                                                         .unwrap_or_else(|| u64::max_value());
 669                                                 let hm_entry = dist.entry($src_node_id);
 670                                                 let old_entry = hm_entry.or_insert_with(|| {
 671                                                         // If there was previously no known way to access
 672                                                         // the source node (recall it goes payee-to-payer) of $chan_id, first add
 673                                                         // a semi-dummy record just to compute the fees to reach the source node.
 674                                                         // This will affect our decision on selecting $chan_id
 675                                                         // as a way to reach the $dest_node_id.
 676                                                         let mut fee_base_msat = u32::max_value();
 677                                                         let mut fee_proportional_millionths = u32::max_value();
 678                                                         if let Some(Some(fees)) = network_nodes.get(&$src_node_id).map(|node| node.lowest_inbound_channel_fees) {
 679                                                                 fee_base_msat = fees.base_msat;
 680                                                                 fee_proportional_millionths = fees.proportional_millionths;
 681                                                         }
 682                                                         PathBuildingHop {
 683                                                                 node_id: $dest_node_id.clone(),
 684                                                                 short_channel_id: 0,
 685                                                                 channel_features: $chan_features,
 686                                                                 fee_msat: 0,
 687                                                                 cltv_expiry_delta: 0,
 688                                                                 src_lowest_inbound_fees: RoutingFees {
 689                                                                         base_msat: fee_base_msat,
 690                                                                         proportional_millionths: fee_proportional_millionths,
 691                                                                 },
 692                                                                 channel_fees: $directional_info.fees,
 693                                                                 next_hops_fee_msat: u64::max_value(),
 694                                                                 hop_use_fee_msat: u64::max_value(),
 695                                                                 total_fee_msat: u64::max_value(),
 696                                                                 htlc_minimum_msat: $directional_info.htlc_minimum_msat,
 697                                                                 path_htlc_minimum_msat,
 698                                                                 path_penalty_msat: u64::max_value(),
 699                                                                 was_processed: false,
 700                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 701                                                                 value_contribution_msat,
 702                                                         }
 703                                                 });
 704
 705                                                 #[allow(unused_mut)] // We only use the mut in cfg(test)
 706                                                 let mut should_process = !old_entry.was_processed;
 707                                                 #[cfg(any(test, feature = "fuzztarget"))]
 708                                                 {
 709                                                         // In test/fuzzing builds, we do extra checks to make sure the skipping
 710                                                         // of already-seen nodes only happens in cases we expect (see below).
 711                                                         if !should_process { should_process = true; }
 712                                                 }
 713
 714                                                 if should_process {
 715                                                         let mut hop_use_fee_msat = 0;
 716                                                         let mut total_fee_msat = $next_hops_fee_msat;
 717
 718                                                         // Ignore hop_use_fee_msat for channel-from-us as we assume all channels-from-us
 719                                                         // will have the same effective-fee
 720                                                         if $src_node_id != our_node_id {
 721                                                                 match compute_fees(amount_to_transfer_over_msat, $directional_info.fees) {
 722                                                                         // max_value means we'll always fail
 723                                                                         // the old_entry.total_fee_msat > total_fee_msat check
 724                                                                         None => total_fee_msat = u64::max_value(),
 725                                                                         Some(fee_msat) => {
 726                                                                                 hop_use_fee_msat = fee_msat;
 727                                                                                 total_fee_msat += hop_use_fee_msat;
 728                                                                                 // When calculating the lowest inbound fees to a node, we
 729                                                                                 // calculate fees here not based on the actual value we think
 730                                                                                 // will flow over this channel, but on the minimum value that
 731                                                                                 // we'll accept flowing over it. The minimum accepted value
 732                                                                                 // is a constant through each path collection run, ensuring
 733                                                                                 // consistent basis. Otherwise we may later find a
 734                                                                                 // different path to the source node that is more expensive,
 735                                                                                 // but which we consider to be cheaper because we are capacity
 736                                                                                 // constrained and the relative fee becomes lower.
 737                                                                                 match compute_fees(minimal_value_contribution_msat, old_entry.src_lowest_inbound_fees)
 738                                                                                                 .map(|a| a.checked_add(total_fee_msat)) {
 739                                                                                         Some(Some(v)) => {
 740                                                                                                 total_fee_msat = v;
 741                                                                                         },
 742                                                                                         _ => {
 743                                                                                                 total_fee_msat = u64::max_value();
 744                                                                                         }
 745                                                                                 };
 746                                                                         }
 747                                                                 }
 748                                                         }
 749
 750                                                         let path_penalty_msat = $next_hops_path_penalty_msat
 751                                                                 .checked_add(scorer.channel_penalty_msat($chan_id.clone(), &$src_node_id, &$dest_node_id))
 752                                                                 .unwrap_or_else(|| u64::max_value());
 753                                                         let new_graph_node = RouteGraphNode {
 754                                                                 node_id: $src_node_id,
 755                                                                 lowest_fee_to_peer_through_node: total_fee_msat,
 756                                                                 lowest_fee_to_node: $next_hops_fee_msat as u64 + hop_use_fee_msat,
 757                                                                 value_contribution_msat: value_contribution_msat,
 758                                                                 path_htlc_minimum_msat,
 759                                                                 path_penalty_msat,
 760                                                         };
 761
 762                                                         // Update the way of reaching $src_node_id with the given $chan_id (from $dest_node_id),
 763                                                         // if this way is cheaper than the already known
 764                                                         // (considering the cost to "reach" this channel from the route destination,
 765                                                         // the cost of using this channel,
 766                                                         // and the cost of routing to the source node of this channel).
 767                                                         // Also, consider that htlc_minimum_msat_difference, because we might end up
 768                                                         // paying it. Consider the following exploit:
 769                                                         // we use 2 paths to transfer 1.5 BTC. One of them is 0-fee normal 1 BTC path,
 770                                                         // and for the other one we picked a 1sat-fee path with htlc_minimum_msat of
 771                                                         // 1 BTC. Now, since the latter is more expensive, we gonna try to cut it
 772                                                         // by 0.5 BTC, but then match htlc_minimum_msat by paying a fee of 0.5 BTC
 773                                                         // to this channel.
 774                                                         // Ideally the scoring could be smarter (e.g. 0.5*htlc_minimum_msat here),
 775                                                         // but it may require additional tracking - we don't want to double-count
 776                                                         // the fees included in $next_hops_path_htlc_minimum_msat, but also
 777                                                         // can't use something that may decrease on future hops.
 778                                                         let old_cost = cmp::max(old_entry.total_fee_msat, old_entry.path_htlc_minimum_msat)
 779                                                                 .checked_add(old_entry.path_penalty_msat)
 780                                                                 .unwrap_or_else(|| u64::max_value());
 781                                                         let new_cost = cmp::max(total_fee_msat, path_htlc_minimum_msat)
 782                                                                 .checked_add(path_penalty_msat)
 783                                                                 .unwrap_or_else(|| u64::max_value());
 784
 785                                                         if !old_entry.was_processed && new_cost < old_cost {
 786                                                                 targets.push(new_graph_node);
 787                                                                 old_entry.next_hops_fee_msat = $next_hops_fee_msat;
 788                                                                 old_entry.hop_use_fee_msat = hop_use_fee_msat;
 789                                                                 old_entry.total_fee_msat = total_fee_msat;
 790                                                                 old_entry.node_id = $dest_node_id.clone();
 791                                                                 old_entry.short_channel_id = $chan_id.clone();
 792                                                                 old_entry.channel_features = $chan_features;
 793                                                                 old_entry.fee_msat = 0; // This value will be later filled with hop_use_fee_msat of the following channel
 794                                                                 old_entry.cltv_expiry_delta = $directional_info.cltv_expiry_delta as u32;
 795                                                                 old_entry.channel_fees = $directional_info.fees;
 796                                                                 old_entry.htlc_minimum_msat = $directional_info.htlc_minimum_msat;
 797                                                                 old_entry.path_htlc_minimum_msat = path_htlc_minimum_msat;
 798                                                                 old_entry.path_penalty_msat = path_penalty_msat;
 799                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 800                                                                 {
 801                                                                         old_entry.value_contribution_msat = value_contribution_msat;
 802                                                                 }
 803                                                                 did_add_update_path_to_src_node = true;
 804                                                         } else if old_entry.was_processed && new_cost < old_cost {
 805                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 806                                                                 {
 807                                                                         // If we're skipping processing a node which was previously
 808                                                                         // processed even though we found another path to it with a
 809                                                                         // cheaper fee, check that it was because the second path we
 810                                                                         // found (which we are processing now) has a lower value
 811                                                                         // contribution due to an HTLC minimum limit.
 812                                                                         //
 813                                                                         // e.g. take a graph with two paths from node 1 to node 2, one
 814                                                                         // through channel A, and one through channel B. Channel A and
 815                                                                         // B are both in the to-process heap, with their scores set by
 816                                                                         // a higher htlc_minimum than fee.
 817                                                                         // Channel A is processed first, and the channels onwards from
 818                                                                         // node 1 are added to the to-process heap. Thereafter, we pop
 819                                                                         // Channel B off of the heap, note that it has a much more
 820                                                                         // restrictive htlc_maximum_msat, and recalculate the fees for
 821                                                                         // all of node 1's channels using the new, reduced, amount.
 822                                                                         //
 823                                                                         // This would be bogus - we'd be selecting a higher-fee path
 824                                                                         // with a lower htlc_maximum_msat instead of the one we'd
 825                                                                         // already decided to use.
 826                                                                         debug_assert!(path_htlc_minimum_msat < old_entry.path_htlc_minimum_msat);
 827                                                                         debug_assert!(
 828                                                                                 value_contribution_msat + path_penalty_msat <
 829                                                                                 old_entry.value_contribution_msat + old_entry.path_penalty_msat
 830                                                                         );
 831                                                                 }
 832                                                         }
 833                                                 }
 834                                         }
 835                                 }
 836                         }
 837                         did_add_update_path_to_src_node
 838                 } }
 839         }
 840
 841         let empty_node_features = NodeFeatures::empty();
 842         // Find ways (channels with destination) to reach a given node and store them
 843         // in the corresponding data structures (routing graph etc).
 844         // $fee_to_target_msat represents how much it costs to reach to this node from the payee,
 845         // meaning how much will be paid in fees after this node (to the best of our knowledge).
 846         // This data can later be helpful to optimize routing (pay lower fees).
 847         macro_rules! add_entries_to_cheapest_to_target_node {
 848                 ( $node: expr, $node_id: expr, $fee_to_target_msat: expr, $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr, $next_hops_path_penalty_msat: expr ) => {
 849                         let skip_node = if let Some(elem) = dist.get_mut(&$node_id) {
 850                                 let was_processed = elem.was_processed;
 851                                 elem.was_processed = true;
 852                                 was_processed
 853                         } else {
 854                                 // Entries are added to dist in add_entry!() when there is a channel from a node.
 855                                 // Because there are no channels from payee, it will not have a dist entry at this point.
 856                                 // If we're processing any other node, it is always be the result of a channel from it.
 857                                 assert_eq!($node_id, payee_node_id);
 858                                 false
 859                         };
 860
 861                         if !skip_node {
 862                                 if let Some(first_channels) = first_hop_targets.get(&$node_id) {
 863                                         for (ref first_hop, ref features, ref outbound_capacity_msat, _) in first_channels {
 864                                                 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);
 865                                         }
 866                                 }
 867
 868                                 let features = if let Some(node_info) = $node.announcement_info.as_ref() {
 869                                         &node_info.features
 870                                 } else {
 871                                         &empty_node_features
 872                                 };
 873
 874                                 if !features.requires_unknown_bits() {
 875                                         for chan_id in $node.channels.iter() {
 876                                                 let chan = network_channels.get(chan_id).unwrap();
 877                                                 if !chan.features.requires_unknown_bits() {
 878                                                         if chan.node_one == $node_id {
 879                                                                 // ie $node is one, ie next hop in A* is two, via the two_to_one channel
 880                                                                 if first_hops.is_none() || chan.node_two != our_node_id {
 881                                                                         if let Some(two_to_one) = chan.two_to_one.as_ref() {
 882                                                                                 if two_to_one.enabled {
 883                                                                                         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);
 884                                                                                 }
 885                                                                         }
 886                                                                 }
 887                                                         } else {
 888                                                                 if first_hops.is_none() || chan.node_one != our_node_id{
 889                                                                         if let Some(one_to_two) = chan.one_to_two.as_ref() {
 890                                                                                 if one_to_two.enabled {
 891                                                                                         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);
 892                                                                                 }
 893                                                                         }
 894                                                                 }
 895                                                         }
 896                                                 }
 897                                         }
 898                                 }
 899                         }
 900                 };
 901         }
 902
 903         let mut payment_paths = Vec::<PaymentPath>::new();
 904
 905         // TODO: diversify by nodes (so that all paths aren't doomed if one node is offline).
 906         'paths_collection: loop {
 907                 // For every new path, start from scratch, except
 908                 // bookkeeped_channels_liquidity_available_msat, which will improve
 909                 // the further iterations of path finding. Also don't erase first_hop_targets.
 910                 targets.clear();
 911                 dist.clear();
 912                 hit_minimum_limit = false;
 913
 914                 // If first hop is a private channel and the only way to reach the payee, this is the only
 915                 // place where it could be added.
 916                 if let Some(first_channels) = first_hop_targets.get(&payee_node_id) {
 917                         for (ref first_hop, ref features, ref outbound_capacity_msat, _) in first_channels {
 918                                 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);
 919                                 log_trace!(logger, "{} direct route to payee via SCID {}", if added { "Added" } else { "Skipped" }, first_hop);
 920                         }
 921                 }
 922
 923                 // Add the payee as a target, so that the payee-to-payer
 924                 // search algorithm knows what to start with.
 925                 match network_nodes.get(&payee_node_id) {
 926                         // The payee is not in our network graph, so nothing to add here.
 927                         // There is still a chance of reaching them via last_hops though,
 928                         // so don't yet fail the payment here.
 929                         // If not, targets.pop() will not even let us enter the loop in step 2.
 930                         None => {},
 931                         Some(node) => {
 932                                 add_entries_to_cheapest_to_target_node!(node, payee_node_id, 0, path_value_msat, 0, 0u64);
 933                         },
 934                 }
 935
 936                 // Step (2).
 937                 // If a caller provided us with last hops, add them to routing targets. Since this happens
 938                 // earlier than general path finding, they will be somewhat prioritized, although currently
 939                 // it matters only if the fees are exactly the same.
 940                 for route in last_hops.iter().filter(|route| !route.0.is_empty()) {
 941                         let first_hop_in_route = &(route.0)[0];
 942                         let have_hop_src_in_graph =
 943                                 // Only add the hops in this route to our candidate set if either
 944                                 // we have a direct channel to the first hop or the first hop is
 945                                 // in the regular network graph.
 946                                 first_hop_targets.get(&NodeId::from_pubkey(&first_hop_in_route.src_node_id)).is_some() ||
 947                                 network_nodes.get(&NodeId::from_pubkey(&first_hop_in_route.src_node_id)).is_some();
 948                         if have_hop_src_in_graph {
 949                                 // We start building the path from reverse, i.e., from payee
 950                                 // to the first RouteHintHop in the path.
 951                                 let hop_iter = route.0.iter().rev();
 952                                 let prev_hop_iter = core::iter::once(payee).chain(
 953                                         route.0.iter().skip(1).rev().map(|hop| &hop.src_node_id));
 954                                 let mut hop_used = true;
 955                                 let mut aggregate_next_hops_fee_msat: u64 = 0;
 956                                 let mut aggregate_next_hops_path_htlc_minimum_msat: u64 = 0;
 957                                 let mut aggregate_next_hops_path_penalty_msat: u64 = 0;
 958
 959                                 for (idx, (hop, prev_hop_id)) in hop_iter.zip(prev_hop_iter).enumerate() {
 960                                         // BOLT 11 doesn't allow inclusion of features for the last hop hints, which
 961                                         // really sucks, cause we're gonna need that eventually.
 962                                         let hop_htlc_minimum_msat: u64 = hop.htlc_minimum_msat.unwrap_or(0);
 963
 964                                         let directional_info = DummyDirectionalChannelInfo {
 965                                                 cltv_expiry_delta: hop.cltv_expiry_delta as u32,
 966                                                 htlc_minimum_msat: hop_htlc_minimum_msat,
 967                                                 htlc_maximum_msat: hop.htlc_maximum_msat,
 968                                                 fees: hop.fees,
 969                                         };
 970
 971                                         let reqd_channel_cap = if let Some (val) = final_value_msat.checked_add(match idx {
 972                                                 0 => 999,
 973                                                 _ => aggregate_next_hops_fee_msat.checked_add(999).unwrap_or(u64::max_value())
 974                                         }) { Some( val / 1000 ) } else { break; }; // converting from msat or breaking if max ~ infinity
 975
 976                                         let src_node_id = NodeId::from_pubkey(&hop.src_node_id);
 977                                         let dest_node_id = NodeId::from_pubkey(&prev_hop_id);
 978                                         aggregate_next_hops_path_penalty_msat = aggregate_next_hops_path_penalty_msat
 979                                                 .checked_add(scorer.channel_penalty_msat(hop.short_channel_id, &src_node_id, &dest_node_id))
 980                                                 .unwrap_or_else(|| u64::max_value());
 981
 982                                         // We assume that the recipient only included route hints for routes which had
 983                                         // sufficient value to route `final_value_msat`. Note that in the case of "0-value"
 984                                         // invoices where the invoice does not specify value this may not be the case, but
 985                                         // better to include the hints than not.
 986                                         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) {
 987                                                 // If this hop was not used then there is no use checking the preceding hops
 988                                                 // in the RouteHint. We can break by just searching for a direct channel between
 989                                                 // last checked hop and first_hop_targets
 990                                                 hop_used = false;
 991                                         }
 992
 993                                         // Searching for a direct channel between last checked hop and first_hop_targets
 994                                         if let Some(first_channels) = first_hop_targets.get(&NodeId::from_pubkey(&prev_hop_id)) {
 995                                                 for (ref first_hop, ref features, ref outbound_capacity_msat, _) in first_channels {
 996                                                         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);
 997                                                 }
 998                                         }
 999
1000                                         if !hop_used {
1001                                                 break;
1002                                         }
1003
1004                                         // In the next values of the iterator, the aggregate fees already reflects
1005                                         // the sum of value sent from payer (final_value_msat) and routing fees
1006                                         // for the last node in the RouteHint. We need to just add the fees to
1007                                         // route through the current node so that the preceeding node (next iteration)
1008                                         // can use it.
1009                                         let hops_fee = compute_fees(aggregate_next_hops_fee_msat + final_value_msat, hop.fees)
1010                                                 .map_or(None, |inc| inc.checked_add(aggregate_next_hops_fee_msat));
1011                                         aggregate_next_hops_fee_msat = if let Some(val) = hops_fee { val } else { break; };
1012
1013                                         let hop_htlc_minimum_msat_inc = if let Some(val) = compute_fees(aggregate_next_hops_path_htlc_minimum_msat, hop.fees) { val } else { break; };
1014                                         let hops_path_htlc_minimum = aggregate_next_hops_path_htlc_minimum_msat
1015                                                 .checked_add(hop_htlc_minimum_msat_inc);
1016                                         aggregate_next_hops_path_htlc_minimum_msat = if let Some(val) = hops_path_htlc_minimum { cmp::max(hop_htlc_minimum_msat, val) } else { break; };
1017
1018                                         if idx == route.0.len() - 1 {
1019                                                 // The last hop in this iterator is the first hop in
1020                                                 // overall RouteHint.
1021                                                 // If this hop connects to a node with which we have a direct channel,
1022                                                 // ignore the network graph and, if the last hop was added, add our
1023                                                 // direct channel to the candidate set.
1024                                                 //
1025                                                 // Note that we *must* check if the last hop was added as `add_entry`
1026                                                 // always assumes that the third argument is a node to which we have a
1027                                                 // path.
1028                                                 if let Some(first_channels) = first_hop_targets.get(&NodeId::from_pubkey(&hop.src_node_id)) {
1029                                                         for (ref first_hop, ref features, ref outbound_capacity_msat, _) in first_channels {
1030                                                                 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);
1031                                                         }
1032                                                 }
1033                                         }
1034                                 }
1035                         }
1036                 }
1037
1038                 log_trace!(logger, "Starting main path collection loop with {} nodes pre-filled from first/last hops.", targets.len());
1039
1040                 // At this point, targets are filled with the data from first and
1041                 // last hops communicated by the caller, and the payment receiver.
1042                 let mut found_new_path = false;
1043
1044                 // Step (3).
1045                 // If this loop terminates due the exhaustion of targets, two situations are possible:
1046                 // - not enough outgoing liquidity:
1047                 //   0 < already_collected_value_msat < final_value_msat
1048                 // - enough outgoing liquidity:
1049                 //   final_value_msat <= already_collected_value_msat < recommended_value_msat
1050                 // Both these cases (and other cases except reaching recommended_value_msat) mean that
1051                 // paths_collection will be stopped because found_new_path==false.
1052                 // This is not necessarily a routing failure.
1053                 'path_construction: while let Some(RouteGraphNode { node_id, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat, path_penalty_msat, .. }) = targets.pop() {
1054
1055                         // Since we're going payee-to-payer, hitting our node as a target means we should stop
1056                         // traversing the graph and arrange the path out of what we found.
1057                         if node_id == our_node_id {
1058                                 let mut new_entry = dist.remove(&our_node_id).unwrap();
1059                                 let mut ordered_hops = vec!((new_entry.clone(), NodeFeatures::empty()));
1060
1061                                 'path_walk: loop {
1062                                         let mut features_set = false;
1063                                         if let Some(first_channels) = first_hop_targets.get(&ordered_hops.last().unwrap().0.node_id) {
1064                                                 for (scid, _, _, ref features) in first_channels {
1065                                                         if *scid == ordered_hops.last().unwrap().0.short_channel_id {
1066                                                                 ordered_hops.last_mut().unwrap().1 = features.clone();
1067                                                                 features_set = true;
1068                                                                 break;
1069                                                         }
1070                                                 }
1071                                         }
1072                                         if !features_set {
1073                                                 if let Some(node) = network_nodes.get(&ordered_hops.last().unwrap().0.node_id) {
1074                                                         if let Some(node_info) = node.announcement_info.as_ref() {
1075                                                                 ordered_hops.last_mut().unwrap().1 = node_info.features.clone();
1076                                                         } else {
1077                                                                 ordered_hops.last_mut().unwrap().1 = NodeFeatures::empty();
1078                                                         }
1079                                                 } else {
1080                                                         // We should be able to fill in features for everything except the last
1081                                                         // hop, if the last hop was provided via a BOLT 11 invoice (though we
1082                                                         // should be able to extend it further as BOLT 11 does have feature
1083                                                         // flags for the last hop node itself).
1084                                                         assert!(ordered_hops.last().unwrap().0.node_id == payee_node_id);
1085                                                 }
1086                                         }
1087
1088                                         // Means we succesfully traversed from the payer to the payee, now
1089                                         // save this path for the payment route. Also, update the liquidity
1090                                         // remaining on the used hops, so that we take them into account
1091                                         // while looking for more paths.
1092                                         if ordered_hops.last().unwrap().0.node_id == payee_node_id {
1093                                                 break 'path_walk;
1094                                         }
1095
1096                                         new_entry = match dist.remove(&ordered_hops.last().unwrap().0.node_id) {
1097                                                 Some(payment_hop) => payment_hop,
1098                                                 // We can't arrive at None because, if we ever add an entry to targets,
1099                                                 // we also fill in the entry in dist (see add_entry!).
1100                                                 None => unreachable!(),
1101                                         };
1102                                         // We "propagate" the fees one hop backward (topologically) here,
1103                                         // so that fees paid for a HTLC forwarding on the current channel are
1104                                         // associated with the previous channel (where they will be subtracted).
1105                                         ordered_hops.last_mut().unwrap().0.fee_msat = new_entry.hop_use_fee_msat;
1106                                         ordered_hops.last_mut().unwrap().0.cltv_expiry_delta = new_entry.cltv_expiry_delta;
1107                                         ordered_hops.push((new_entry.clone(), NodeFeatures::empty()));
1108                                 }
1109                                 ordered_hops.last_mut().unwrap().0.fee_msat = value_contribution_msat;
1110                                 ordered_hops.last_mut().unwrap().0.hop_use_fee_msat = 0;
1111                                 ordered_hops.last_mut().unwrap().0.cltv_expiry_delta = final_cltv;
1112
1113                                 log_trace!(logger, "Found a path back to us from the target with {} hops contributing up to {} msat: {:?}",
1114                                         ordered_hops.len(), value_contribution_msat, ordered_hops);
1115
1116                                 let mut payment_path = PaymentPath {hops: ordered_hops};
1117
1118                                 // We could have possibly constructed a slightly inconsistent path: since we reduce
1119                                 // value being transferred along the way, we could have violated htlc_minimum_msat
1120                                 // on some channels we already passed (assuming dest->source direction). Here, we
1121                                 // recompute the fees again, so that if that's the case, we match the currently
1122                                 // underpaid htlc_minimum_msat with fees.
1123                                 payment_path.update_value_and_recompute_fees(cmp::min(value_contribution_msat, final_value_msat));
1124
1125                                 // Since a path allows to transfer as much value as
1126                                 // the smallest channel it has ("bottleneck"), we should recompute
1127                                 // the fees so sender HTLC don't overpay fees when traversing
1128                                 // larger channels than the bottleneck. This may happen because
1129                                 // when we were selecting those channels we were not aware how much value
1130                                 // this path will transfer, and the relative fee for them
1131                                 // might have been computed considering a larger value.
1132                                 // Remember that we used these channels so that we don't rely
1133                                 // on the same liquidity in future paths.
1134                                 let mut prevented_redundant_path_selection = false;
1135                                 for (payment_hop, _) in payment_path.hops.iter() {
1136                                         let channel_liquidity_available_msat = bookkeeped_channels_liquidity_available_msat.get_mut(&payment_hop.short_channel_id).unwrap();
1137                                         let mut spent_on_hop_msat = value_contribution_msat;
1138                                         let next_hops_fee_msat = payment_hop.next_hops_fee_msat;
1139                                         spent_on_hop_msat += next_hops_fee_msat;
1140                                         if spent_on_hop_msat == *channel_liquidity_available_msat {
1141                                                 // If this path used all of this channel's available liquidity, we know
1142                                                 // this path will not be selected again in the next loop iteration.
1143                                                 prevented_redundant_path_selection = true;
1144                                         }
1145                                         *channel_liquidity_available_msat -= spent_on_hop_msat;
1146                                 }
1147                                 if !prevented_redundant_path_selection {
1148                                         // If we weren't capped by hitting a liquidity limit on a channel in the path,
1149                                         // we'll probably end up picking the same path again on the next iteration.
1150                                         // Decrease the available liquidity of a hop in the middle of the path.
1151                                         let victim_scid = payment_path.hops[(payment_path.hops.len() - 1) / 2].0.short_channel_id;
1152                                         log_trace!(logger, "Disabling channel {} for future path building iterations to avoid duplicates.", victim_scid);
1153                                         let victim_liquidity = bookkeeped_channels_liquidity_available_msat.get_mut(&victim_scid).unwrap();
1154                                         *victim_liquidity = 0;
1155                                 }
1156
1157                                 // Track the total amount all our collected paths allow to send so that we:
1158                                 // - know when to stop looking for more paths
1159                                 // - know which of the hops are useless considering how much more sats we need
1160                                 //   (contributes_sufficient_value)
1161                                 already_collected_value_msat += value_contribution_msat;
1162
1163                                 payment_paths.push(payment_path);
1164                                 found_new_path = true;
1165                                 break 'path_construction;
1166                         }
1167
1168                         // If we found a path back to the payee, we shouldn't try to process it again. This is
1169                         // the equivalent of the `elem.was_processed` check in
1170                         // add_entries_to_cheapest_to_target_node!() (see comment there for more info).
1171                         if node_id == payee_node_id { continue 'path_construction; }
1172
1173                         // Otherwise, since the current target node is not us,
1174                         // keep "unrolling" the payment graph from payee to payer by
1175                         // finding a way to reach the current target from the payer side.
1176                         match network_nodes.get(&node_id) {
1177                                 None => {},
1178                                 Some(node) => {
1179                                         add_entries_to_cheapest_to_target_node!(node, node_id, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat, path_penalty_msat);
1180                                 },
1181                         }
1182                 }
1183
1184                 if !allow_mpp {
1185                         // If we don't support MPP, no use trying to gather more value ever.
1186                         break 'paths_collection;
1187                 }
1188
1189                 // Step (4).
1190                 // Stop either when the recommended value is reached or if no new path was found in this
1191                 // iteration.
1192                 // In the latter case, making another path finding attempt won't help,
1193                 // because we deterministically terminated the search due to low liquidity.
1194                 if already_collected_value_msat >= recommended_value_msat || !found_new_path {
1195                         log_trace!(logger, "Have now collected {} msat (seeking {} msat) in paths. Last path loop {} a new path.",
1196                                 already_collected_value_msat, recommended_value_msat, if found_new_path { "found" } else { "did not find" });
1197                         break 'paths_collection;
1198                 } else if found_new_path && already_collected_value_msat == final_value_msat && payment_paths.len() == 1 {
1199                         // Further, if this was our first walk of the graph, and we weren't limited by an
1200                         // htlc_minimum_msat, return immediately because this path should suffice. If we were
1201                         // limited by an htlc_minimum_msat value, find another path with a higher value,
1202                         // potentially allowing us to pay fees to meet the htlc_minimum on the new path while
1203                         // still keeping a lower total fee than this path.
1204                         if !hit_minimum_limit {
1205                                 log_trace!(logger, "Collected exactly our payment amount on the first pass, without hitting an htlc_minimum_msat limit, exiting.");
1206                                 break 'paths_collection;
1207                         }
1208                         log_trace!(logger, "Collected our payment amount on the first pass, but running again to collect extra paths with a potentially higher limit.");
1209                         path_value_msat = recommended_value_msat;
1210                 }
1211         }
1212
1213         // Step (5).
1214         if payment_paths.len() == 0 {
1215                 return Err(LightningError{err: "Failed to find a path to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1216         }
1217
1218         if already_collected_value_msat < final_value_msat {
1219                 return Err(LightningError{err: "Failed to find a sufficient route to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1220         }
1221
1222         // Sort by total fees and take the best paths.
1223         payment_paths.sort_by_key(|path| path.get_total_fee_paid_msat());
1224         if payment_paths.len() > 50 {
1225                 payment_paths.truncate(50);
1226         }
1227
1228         // Draw multiple sufficient routes by randomly combining the selected paths.
1229         let mut drawn_routes = Vec::new();
1230         for i in 0..payment_paths.len() {
1231                 let mut cur_route = Vec::<PaymentPath>::new();
1232                 let mut aggregate_route_value_msat = 0;
1233
1234                 // Step (6).
1235                 // TODO: real random shuffle
1236                 // Currently just starts with i_th and goes up to i-1_th in a looped way.
1237                 let cur_payment_paths = [&payment_paths[i..], &payment_paths[..i]].concat();
1238
1239                 // Step (7).
1240                 for payment_path in cur_payment_paths {
1241                         cur_route.push(payment_path.clone());
1242                         aggregate_route_value_msat += payment_path.get_value_msat();
1243                         if aggregate_route_value_msat > final_value_msat {
1244                                 // Last path likely overpaid. Substract it from the most expensive
1245                                 // (in terms of proportional fee) path in this route and recompute fees.
1246                                 // This might be not the most economically efficient way, but fewer paths
1247                                 // also makes routing more reliable.
1248                                 let mut overpaid_value_msat = aggregate_route_value_msat - final_value_msat;
1249
1250                                 // First, drop some expensive low-value paths entirely if possible.
1251                                 // Sort by value so that we drop many really-low values first, since
1252                                 // fewer paths is better: the payment is less likely to fail.
1253                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1254                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1255                                 cur_route.sort_by_key(|path| path.get_value_msat());
1256                                 // We should make sure that at least 1 path left.
1257                                 let mut paths_left = cur_route.len();
1258                                 cur_route.retain(|path| {
1259                                         if paths_left == 1 {
1260                                                 return true
1261                                         }
1262                                         let mut keep = true;
1263                                         let path_value_msat = path.get_value_msat();
1264                                         if path_value_msat <= overpaid_value_msat {
1265                                                 keep = false;
1266                                                 overpaid_value_msat -= path_value_msat;
1267                                                 paths_left -= 1;
1268                                         }
1269                                         keep
1270                                 });
1271
1272                                 if overpaid_value_msat == 0 {
1273                                         break;
1274                                 }
1275
1276                                 assert!(cur_route.len() > 0);
1277
1278                                 // Step (8).
1279                                 // Now, substract the overpaid value from the most-expensive path.
1280                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1281                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1282                                 cur_route.sort_by_key(|path| { path.hops.iter().map(|hop| hop.0.channel_fees.proportional_millionths as u64).sum::<u64>() });
1283                                 let expensive_payment_path = cur_route.first_mut().unwrap();
1284                                 // We already dropped all the small channels above, meaning all the
1285                                 // remaining channels are larger than remaining overpaid_value_msat.
1286                                 // Thus, this can't be negative.
1287                                 let expensive_path_new_value_msat = expensive_payment_path.get_value_msat() - overpaid_value_msat;
1288                                 expensive_payment_path.update_value_and_recompute_fees(expensive_path_new_value_msat);
1289                                 break;
1290                         }
1291                 }
1292                 drawn_routes.push(cur_route);
1293         }
1294
1295         // Step (9).
1296         // Select the best route by lowest total fee.
1297         drawn_routes.sort_by_key(|paths| paths.iter().map(|path| path.get_total_fee_paid_msat()).sum::<u64>());
1298         let mut selected_paths = Vec::<Vec<Result<RouteHop, LightningError>>>::new();
1299         for payment_path in drawn_routes.first().unwrap() {
1300                 selected_paths.push(payment_path.hops.iter().map(|(payment_hop, node_features)| {
1301                         Ok(RouteHop {
1302                                 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)})?,
1303                                 node_features: node_features.clone(),
1304                                 short_channel_id: payment_hop.short_channel_id,
1305                                 channel_features: payment_hop.channel_features.clone(),
1306                                 fee_msat: payment_hop.fee_msat,
1307                                 cltv_expiry_delta: payment_hop.cltv_expiry_delta,
1308                         })
1309                 }).collect());
1310         }
1311
1312         if let Some(features) = &payee_features {
1313                 for path in selected_paths.iter_mut() {
1314                         if let Ok(route_hop) = path.last_mut().unwrap() {
1315                                 route_hop.node_features = features.to_context();
1316                         }
1317                 }
1318         }
1319
1320         let route = Route { paths: selected_paths.into_iter().map(|path| path.into_iter().collect()).collect::<Result<Vec<_>, _>>()? };
1321         log_info!(logger, "Got route to {}: {}", payee, log_route!(route));
1322         Ok(route)
1323 }
1324
1325 #[cfg(test)]
1326 mod tests {
1327         use routing;
1328         use routing::network_graph::{NetworkGraph, NetGraphMsgHandler, NodeId};
1329         use routing::router::{get_route, Route, RouteHint, RouteHintHop, RouteHop, RoutingFees};
1330         use routing::scorer::Scorer;
1331         use chain::transaction::OutPoint;
1332         use ln::features::{ChannelFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
1333         use ln::msgs::{ErrorAction, LightningError, OptionalField, UnsignedChannelAnnouncement, ChannelAnnouncement, RoutingMessageHandler,
1334            NodeAnnouncement, UnsignedNodeAnnouncement, ChannelUpdate, UnsignedChannelUpdate};
1335         use ln::channelmanager;
1336         use util::test_utils;
1337         use util::ser::Writeable;
1338
1339         use bitcoin::hashes::sha256d::Hash as Sha256dHash;
1340         use bitcoin::hashes::Hash;
1341         use bitcoin::network::constants::Network;
1342         use bitcoin::blockdata::constants::genesis_block;
1343         use bitcoin::blockdata::script::Builder;
1344         use bitcoin::blockdata::opcodes;
1345         use bitcoin::blockdata::transaction::TxOut;
1346
1347         use hex;
1348
1349         use bitcoin::secp256k1::key::{PublicKey,SecretKey};
1350         use bitcoin::secp256k1::{Secp256k1, All};
1351
1352         use prelude::*;
1353         use sync::{self, Arc};
1354
1355         fn get_channel_details(short_channel_id: Option<u64>, node_id: PublicKey,
1356                         features: InitFeatures, outbound_capacity_msat: u64) -> channelmanager::ChannelDetails {
1357                 channelmanager::ChannelDetails {
1358                         channel_id: [0; 32],
1359                         counterparty: channelmanager::ChannelCounterparty {
1360                                 features,
1361                                 node_id,
1362                                 unspendable_punishment_reserve: 0,
1363                                 forwarding_info: None,
1364                         },
1365                         funding_txo: Some(OutPoint { txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(), index: 0 }),
1366                         short_channel_id,
1367                         channel_value_satoshis: 0,
1368                         user_channel_id: 0,
1369                         outbound_capacity_msat,
1370                         inbound_capacity_msat: 42,
1371                         unspendable_punishment_reserve: None,
1372                         confirmations_required: None,
1373                         force_close_spend_delay: None,
1374                         is_outbound: true, is_funding_locked: true,
1375                         is_usable: true, is_public: true,
1376                 }
1377         }
1378
1379         // Using the same keys for LN and BTC ids
1380         fn add_channel(
1381                 net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>,
1382                 secp_ctx: &Secp256k1<All>, node_1_privkey: &SecretKey, node_2_privkey: &SecretKey, features: ChannelFeatures, short_channel_id: u64
1383         ) {
1384                 let node_id_1 = PublicKey::from_secret_key(&secp_ctx, node_1_privkey);
1385                 let node_id_2 = PublicKey::from_secret_key(&secp_ctx, node_2_privkey);
1386
1387                 let unsigned_announcement = UnsignedChannelAnnouncement {
1388                         features,
1389                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1390                         short_channel_id,
1391                         node_id_1,
1392                         node_id_2,
1393                         bitcoin_key_1: node_id_1,
1394                         bitcoin_key_2: node_id_2,
1395                         excess_data: Vec::new(),
1396                 };
1397
1398                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1399                 let valid_announcement = ChannelAnnouncement {
1400                         node_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1401                         node_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1402                         bitcoin_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1403                         bitcoin_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1404                         contents: unsigned_announcement.clone(),
1405                 };
1406                 match net_graph_msg_handler.handle_channel_announcement(&valid_announcement) {
1407                         Ok(res) => assert!(res),
1408                         _ => panic!()
1409                 };
1410         }
1411
1412         fn update_channel(
1413                 net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>,
1414                 secp_ctx: &Secp256k1<All>, node_privkey: &SecretKey, update: UnsignedChannelUpdate
1415         ) {
1416                 let msghash = hash_to_message!(&Sha256dHash::hash(&update.encode()[..])[..]);
1417                 let valid_channel_update = ChannelUpdate {
1418                         signature: secp_ctx.sign(&msghash, node_privkey),
1419                         contents: update.clone()
1420                 };
1421
1422                 match net_graph_msg_handler.handle_channel_update(&valid_channel_update) {
1423                         Ok(res) => assert!(res),
1424                         Err(_) => panic!()
1425                 };
1426         }
1427
1428         fn add_or_update_node(
1429                 net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>,
1430                 secp_ctx: &Secp256k1<All>, node_privkey: &SecretKey, features: NodeFeatures, timestamp: u32
1431         ) {
1432                 let node_id = PublicKey::from_secret_key(&secp_ctx, node_privkey);
1433                 let unsigned_announcement = UnsignedNodeAnnouncement {
1434                         features,
1435                         timestamp,
1436                         node_id,
1437                         rgb: [0; 3],
1438                         alias: [0; 32],
1439                         addresses: Vec::new(),
1440                         excess_address_data: Vec::new(),
1441                         excess_data: Vec::new(),
1442                 };
1443                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1444                 let valid_announcement = NodeAnnouncement {
1445                         signature: secp_ctx.sign(&msghash, node_privkey),
1446                         contents: unsigned_announcement.clone()
1447                 };
1448
1449                 match net_graph_msg_handler.handle_node_announcement(&valid_announcement) {
1450                         Ok(_) => (),
1451                         Err(_) => panic!()
1452                 };
1453         }
1454
1455         fn get_nodes(secp_ctx: &Secp256k1<All>) -> (SecretKey, PublicKey, Vec<SecretKey>, Vec<PublicKey>) {
1456                 let privkeys: Vec<SecretKey> = (2..10).map(|i| {
1457                         SecretKey::from_slice(&hex::decode(format!("{:02}", i).repeat(32)).unwrap()[..]).unwrap()
1458                 }).collect();
1459
1460                 let pubkeys = privkeys.iter().map(|secret| PublicKey::from_secret_key(&secp_ctx, secret)).collect();
1461
1462                 let our_privkey = SecretKey::from_slice(&hex::decode("01".repeat(32)).unwrap()[..]).unwrap();
1463                 let our_id = PublicKey::from_secret_key(&secp_ctx, &our_privkey);
1464
1465                 (our_privkey, our_id, privkeys, pubkeys)
1466         }
1467
1468         fn id_to_feature_flags(id: u8) -> Vec<u8> {
1469                 // Set the feature flags to the id'th odd (ie non-required) feature bit so that we can
1470                 // test for it later.
1471                 let idx = (id - 1) * 2 + 1;
1472                 if idx > 8*3 {
1473                         vec![1 << (idx - 8*3), 0, 0, 0]
1474                 } else if idx > 8*2 {
1475                         vec![1 << (idx - 8*2), 0, 0]
1476                 } else if idx > 8*1 {
1477                         vec![1 << (idx - 8*1), 0]
1478                 } else {
1479                         vec![1 << idx]
1480                 }
1481         }
1482
1483         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>) {
1484                 let secp_ctx = Secp256k1::new();
1485                 let logger = Arc::new(test_utils::TestLogger::new());
1486                 let chain_monitor = Arc::new(test_utils::TestChainSource::new(Network::Testnet));
1487                 let network_graph = NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash());
1488                 let net_graph_msg_handler = NetGraphMsgHandler::new(network_graph, None, Arc::clone(&logger));
1489                 // Build network from our_id to node6:
1490                 //
1491                 //        -1(1)2-  node0  -1(3)2-
1492                 //       /                       \
1493                 // our_id -1(12)2- node7 -1(13)2--- node2
1494                 //       \                       /
1495                 //        -1(2)2-  node1  -1(4)2-
1496                 //
1497                 //
1498                 // chan1  1-to-2: disabled
1499                 // chan1  2-to-1: enabled, 0 fee
1500                 //
1501                 // chan2  1-to-2: enabled, ignored fee
1502                 // chan2  2-to-1: enabled, 0 fee
1503                 //
1504                 // chan3  1-to-2: enabled, 0 fee
1505                 // chan3  2-to-1: enabled, 100 msat fee
1506                 //
1507                 // chan4  1-to-2: enabled, 100% fee
1508                 // chan4  2-to-1: enabled, 0 fee
1509                 //
1510                 // chan12 1-to-2: enabled, ignored fee
1511                 // chan12 2-to-1: enabled, 0 fee
1512                 //
1513                 // chan13 1-to-2: enabled, 200% fee
1514                 // chan13 2-to-1: enabled, 0 fee
1515                 //
1516                 //
1517                 //       -1(5)2- node3 -1(8)2--
1518                 //       |         2          |
1519                 //       |       (11)         |
1520                 //      /          1           \
1521                 // node2--1(6)2- node4 -1(9)2--- node6 (not in global route map)
1522                 //      \                      /
1523                 //       -1(7)2- node5 -1(10)2-
1524                 //
1525                 // Channels 5, 8, 9 and 10 are private channels.
1526                 //
1527                 // chan5  1-to-2: enabled, 100 msat fee
1528                 // chan5  2-to-1: enabled, 0 fee
1529                 //
1530                 // chan6  1-to-2: enabled, 0 fee
1531                 // chan6  2-to-1: enabled, 0 fee
1532                 //
1533                 // chan7  1-to-2: enabled, 100% fee
1534                 // chan7  2-to-1: enabled, 0 fee
1535                 //
1536                 // chan8  1-to-2: enabled, variable fee (0 then 1000 msat)
1537                 // chan8  2-to-1: enabled, 0 fee
1538                 //
1539                 // chan9  1-to-2: enabled, 1001 msat fee
1540                 // chan9  2-to-1: enabled, 0 fee
1541                 //
1542                 // chan10 1-to-2: enabled, 0 fee
1543                 // chan10 2-to-1: enabled, 0 fee
1544                 //
1545                 // chan11 1-to-2: enabled, 0 fee
1546                 // chan11 2-to-1: enabled, 0 fee
1547
1548                 let (our_privkey, _, privkeys, _) = get_nodes(&secp_ctx);
1549
1550                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[0], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
1551                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1552                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1553                         short_channel_id: 1,
1554                         timestamp: 1,
1555                         flags: 1,
1556                         cltv_expiry_delta: 0,
1557                         htlc_minimum_msat: 0,
1558                         htlc_maximum_msat: OptionalField::Absent,
1559                         fee_base_msat: 0,
1560                         fee_proportional_millionths: 0,
1561                         excess_data: Vec::new()
1562                 });
1563
1564                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
1565
1566                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
1567                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1568                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1569                         short_channel_id: 2,
1570                         timestamp: 1,
1571                         flags: 0,
1572                         cltv_expiry_delta: u16::max_value(),
1573                         htlc_minimum_msat: 0,
1574                         htlc_maximum_msat: OptionalField::Absent,
1575                         fee_base_msat: u32::max_value(),
1576                         fee_proportional_millionths: u32::max_value(),
1577                         excess_data: Vec::new()
1578                 });
1579                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1580                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1581                         short_channel_id: 2,
1582                         timestamp: 1,
1583                         flags: 1,
1584                         cltv_expiry_delta: 0,
1585                         htlc_minimum_msat: 0,
1586                         htlc_maximum_msat: OptionalField::Absent,
1587                         fee_base_msat: 0,
1588                         fee_proportional_millionths: 0,
1589                         excess_data: Vec::new()
1590                 });
1591
1592                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
1593
1594                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[7], ChannelFeatures::from_le_bytes(id_to_feature_flags(12)), 12);
1595                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1596                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1597                         short_channel_id: 12,
1598                         timestamp: 1,
1599                         flags: 0,
1600                         cltv_expiry_delta: u16::max_value(),
1601                         htlc_minimum_msat: 0,
1602                         htlc_maximum_msat: OptionalField::Absent,
1603                         fee_base_msat: u32::max_value(),
1604                         fee_proportional_millionths: u32::max_value(),
1605                         excess_data: Vec::new()
1606                 });
1607                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1608                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1609                         short_channel_id: 12,
1610                         timestamp: 1,
1611                         flags: 1,
1612                         cltv_expiry_delta: 0,
1613                         htlc_minimum_msat: 0,
1614                         htlc_maximum_msat: OptionalField::Absent,
1615                         fee_base_msat: 0,
1616                         fee_proportional_millionths: 0,
1617                         excess_data: Vec::new()
1618                 });
1619
1620                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], NodeFeatures::from_le_bytes(id_to_feature_flags(8)), 0);
1621
1622                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
1623                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1624                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1625                         short_channel_id: 3,
1626                         timestamp: 1,
1627                         flags: 0,
1628                         cltv_expiry_delta: (3 << 8) | 1,
1629                         htlc_minimum_msat: 0,
1630                         htlc_maximum_msat: OptionalField::Absent,
1631                         fee_base_msat: 0,
1632                         fee_proportional_millionths: 0,
1633                         excess_data: Vec::new()
1634                 });
1635                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1636                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1637                         short_channel_id: 3,
1638                         timestamp: 1,
1639                         flags: 1,
1640                         cltv_expiry_delta: (3 << 8) | 2,
1641                         htlc_minimum_msat: 0,
1642                         htlc_maximum_msat: OptionalField::Absent,
1643                         fee_base_msat: 100,
1644                         fee_proportional_millionths: 0,
1645                         excess_data: Vec::new()
1646                 });
1647
1648                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
1649                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1650                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1651                         short_channel_id: 4,
1652                         timestamp: 1,
1653                         flags: 0,
1654                         cltv_expiry_delta: (4 << 8) | 1,
1655                         htlc_minimum_msat: 0,
1656                         htlc_maximum_msat: OptionalField::Absent,
1657                         fee_base_msat: 0,
1658                         fee_proportional_millionths: 1000000,
1659                         excess_data: Vec::new()
1660                 });
1661                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1662                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1663                         short_channel_id: 4,
1664                         timestamp: 1,
1665                         flags: 1,
1666                         cltv_expiry_delta: (4 << 8) | 2,
1667                         htlc_minimum_msat: 0,
1668                         htlc_maximum_msat: OptionalField::Absent,
1669                         fee_base_msat: 0,
1670                         fee_proportional_millionths: 0,
1671                         excess_data: Vec::new()
1672                 });
1673
1674                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(13)), 13);
1675                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1676                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1677                         short_channel_id: 13,
1678                         timestamp: 1,
1679                         flags: 0,
1680                         cltv_expiry_delta: (13 << 8) | 1,
1681                         htlc_minimum_msat: 0,
1682                         htlc_maximum_msat: OptionalField::Absent,
1683                         fee_base_msat: 0,
1684                         fee_proportional_millionths: 2000000,
1685                         excess_data: Vec::new()
1686                 });
1687                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1688                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1689                         short_channel_id: 13,
1690                         timestamp: 1,
1691                         flags: 1,
1692                         cltv_expiry_delta: (13 << 8) | 2,
1693                         htlc_minimum_msat: 0,
1694                         htlc_maximum_msat: OptionalField::Absent,
1695                         fee_base_msat: 0,
1696                         fee_proportional_millionths: 0,
1697                         excess_data: Vec::new()
1698                 });
1699
1700                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
1701
1702                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
1703                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1704                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1705                         short_channel_id: 6,
1706                         timestamp: 1,
1707                         flags: 0,
1708                         cltv_expiry_delta: (6 << 8) | 1,
1709                         htlc_minimum_msat: 0,
1710                         htlc_maximum_msat: OptionalField::Absent,
1711                         fee_base_msat: 0,
1712                         fee_proportional_millionths: 0,
1713                         excess_data: Vec::new()
1714                 });
1715                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1716                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1717                         short_channel_id: 6,
1718                         timestamp: 1,
1719                         flags: 1,
1720                         cltv_expiry_delta: (6 << 8) | 2,
1721                         htlc_minimum_msat: 0,
1722                         htlc_maximum_msat: OptionalField::Absent,
1723                         fee_base_msat: 0,
1724                         fee_proportional_millionths: 0,
1725                         excess_data: Vec::new(),
1726                 });
1727
1728                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(11)), 11);
1729                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1730                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1731                         short_channel_id: 11,
1732                         timestamp: 1,
1733                         flags: 0,
1734                         cltv_expiry_delta: (11 << 8) | 1,
1735                         htlc_minimum_msat: 0,
1736                         htlc_maximum_msat: OptionalField::Absent,
1737                         fee_base_msat: 0,
1738                         fee_proportional_millionths: 0,
1739                         excess_data: Vec::new()
1740                 });
1741                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
1742                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1743                         short_channel_id: 11,
1744                         timestamp: 1,
1745                         flags: 1,
1746                         cltv_expiry_delta: (11 << 8) | 2,
1747                         htlc_minimum_msat: 0,
1748                         htlc_maximum_msat: OptionalField::Absent,
1749                         fee_base_msat: 0,
1750                         fee_proportional_millionths: 0,
1751                         excess_data: Vec::new()
1752                 });
1753
1754                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(5)), 0);
1755
1756                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
1757
1758                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[5], ChannelFeatures::from_le_bytes(id_to_feature_flags(7)), 7);
1759                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1760                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1761                         short_channel_id: 7,
1762                         timestamp: 1,
1763                         flags: 0,
1764                         cltv_expiry_delta: (7 << 8) | 1,
1765                         htlc_minimum_msat: 0,
1766                         htlc_maximum_msat: OptionalField::Absent,
1767                         fee_base_msat: 0,
1768                         fee_proportional_millionths: 1000000,
1769                         excess_data: Vec::new()
1770                 });
1771                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[5], UnsignedChannelUpdate {
1772                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1773                         short_channel_id: 7,
1774                         timestamp: 1,
1775                         flags: 1,
1776                         cltv_expiry_delta: (7 << 8) | 2,
1777                         htlc_minimum_msat: 0,
1778                         htlc_maximum_msat: OptionalField::Absent,
1779                         fee_base_msat: 0,
1780                         fee_proportional_millionths: 0,
1781                         excess_data: Vec::new()
1782                 });
1783
1784                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[5], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
1785
1786                 (secp_ctx, net_graph_msg_handler, chain_monitor, logger)
1787         }
1788
1789         #[test]
1790         fn simple_route_test() {
1791                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1792                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1793                 let scorer = Scorer::new(0);
1794
1795                 // Simple route to 2 via 1
1796
1797                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, None, &Vec::new(), 0, 42, Arc::clone(&logger), &scorer) {
1798                         assert_eq!(err, "Cannot send a payment of 0 msat");
1799                 } else { panic!(); }
1800
1801                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger), &scorer).unwrap();
1802                 assert_eq!(route.paths[0].len(), 2);
1803
1804                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
1805                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1806                 assert_eq!(route.paths[0][0].fee_msat, 100);
1807                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
1808                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
1809                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
1810
1811                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1812                 assert_eq!(route.paths[0][1].short_channel_id, 4);
1813                 assert_eq!(route.paths[0][1].fee_msat, 100);
1814                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1815                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1816                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
1817         }
1818
1819         #[test]
1820         fn invalid_first_hop_test() {
1821                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1822                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1823                 let scorer = Scorer::new(0);
1824
1825                 // Simple route to 2 via 1
1826
1827                 let our_chans = vec![get_channel_details(Some(2), our_id, InitFeatures::from_le_bytes(vec![0b11]), 100000)];
1828
1829                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger), &scorer) {
1830                         assert_eq!(err, "First hop cannot have our_node_pubkey as a destination.");
1831                 } else { panic!(); }
1832
1833                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger), &scorer).unwrap();
1834                 assert_eq!(route.paths[0].len(), 2);
1835         }
1836
1837         #[test]
1838         fn htlc_minimum_test() {
1839                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1840                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1841                 let scorer = Scorer::new(0);
1842
1843                 // Simple route to 2 via 1
1844
1845                 // Disable other paths
1846                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1847                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1848                         short_channel_id: 12,
1849                         timestamp: 2,
1850                         flags: 2, // to disable
1851                         cltv_expiry_delta: 0,
1852                         htlc_minimum_msat: 0,
1853                         htlc_maximum_msat: OptionalField::Absent,
1854                         fee_base_msat: 0,
1855                         fee_proportional_millionths: 0,
1856                         excess_data: Vec::new()
1857                 });
1858                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1859                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1860                         short_channel_id: 3,
1861                         timestamp: 2,
1862                         flags: 2, // to disable
1863                         cltv_expiry_delta: 0,
1864                         htlc_minimum_msat: 0,
1865                         htlc_maximum_msat: OptionalField::Absent,
1866                         fee_base_msat: 0,
1867                         fee_proportional_millionths: 0,
1868                         excess_data: Vec::new()
1869                 });
1870                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1871                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1872                         short_channel_id: 13,
1873                         timestamp: 2,
1874                         flags: 2, // to disable
1875                         cltv_expiry_delta: 0,
1876                         htlc_minimum_msat: 0,
1877                         htlc_maximum_msat: OptionalField::Absent,
1878                         fee_base_msat: 0,
1879                         fee_proportional_millionths: 0,
1880                         excess_data: Vec::new()
1881                 });
1882                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1883                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1884                         short_channel_id: 6,
1885                         timestamp: 2,
1886                         flags: 2, // to disable
1887                         cltv_expiry_delta: 0,
1888                         htlc_minimum_msat: 0,
1889                         htlc_maximum_msat: OptionalField::Absent,
1890                         fee_base_msat: 0,
1891                         fee_proportional_millionths: 0,
1892                         excess_data: Vec::new()
1893                 });
1894                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1895                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1896                         short_channel_id: 7,
1897                         timestamp: 2,
1898                         flags: 2, // to disable
1899                         cltv_expiry_delta: 0,
1900                         htlc_minimum_msat: 0,
1901                         htlc_maximum_msat: OptionalField::Absent,
1902                         fee_base_msat: 0,
1903                         fee_proportional_millionths: 0,
1904                         excess_data: Vec::new()
1905                 });
1906
1907                 // Check against amount_to_transfer_over_msat.
1908                 // Set minimal HTLC of 200_000_000 msat.
1909                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1910                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1911                         short_channel_id: 2,
1912                         timestamp: 3,
1913                         flags: 0,
1914                         cltv_expiry_delta: 0,
1915                         htlc_minimum_msat: 200_000_000,
1916                         htlc_maximum_msat: OptionalField::Absent,
1917                         fee_base_msat: 0,
1918                         fee_proportional_millionths: 0,
1919                         excess_data: Vec::new()
1920                 });
1921
1922                 // Second hop only allows to forward 199_999_999 at most, thus not allowing the first hop to
1923                 // be used.
1924                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1925                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1926                         short_channel_id: 4,
1927                         timestamp: 3,
1928                         flags: 0,
1929                         cltv_expiry_delta: 0,
1930                         htlc_minimum_msat: 0,
1931                         htlc_maximum_msat: OptionalField::Present(199_999_999),
1932                         fee_base_msat: 0,
1933                         fee_proportional_millionths: 0,
1934                         excess_data: Vec::new()
1935                 });
1936
1937                 // Not possible to send 199_999_999, because the minimum on channel=2 is 200_000_000.
1938                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, None, &Vec::new(), 199_999_999, 42, Arc::clone(&logger), &scorer) {
1939                         assert_eq!(err, "Failed to find a path to the given destination");
1940                 } else { panic!(); }
1941
1942                 // Lift the restriction on the first hop.
1943                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1944                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1945                         short_channel_id: 2,
1946                         timestamp: 4,
1947                         flags: 0,
1948                         cltv_expiry_delta: 0,
1949                         htlc_minimum_msat: 0,
1950                         htlc_maximum_msat: OptionalField::Absent,
1951                         fee_base_msat: 0,
1952                         fee_proportional_millionths: 0,
1953                         excess_data: Vec::new()
1954                 });
1955
1956                 // A payment above the minimum should pass
1957                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, None, &Vec::new(), 199_999_999, 42, Arc::clone(&logger), &scorer).unwrap();
1958                 assert_eq!(route.paths[0].len(), 2);
1959         }
1960
1961         #[test]
1962         fn htlc_minimum_overpay_test() {
1963                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1964                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1965                 let scorer = Scorer::new(0);
1966
1967                 // A route to node#2 via two paths.
1968                 // One path allows transferring 35-40 sats, another one also allows 35-40 sats.
1969                 // Thus, they can't send 60 without overpaying.
1970                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1971                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1972                         short_channel_id: 2,
1973                         timestamp: 2,
1974                         flags: 0,
1975                         cltv_expiry_delta: 0,
1976                         htlc_minimum_msat: 35_000,
1977                         htlc_maximum_msat: OptionalField::Present(40_000),
1978                         fee_base_msat: 0,
1979                         fee_proportional_millionths: 0,
1980                         excess_data: Vec::new()
1981                 });
1982                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1983                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1984                         short_channel_id: 12,
1985                         timestamp: 3,
1986                         flags: 0,
1987                         cltv_expiry_delta: 0,
1988                         htlc_minimum_msat: 35_000,
1989                         htlc_maximum_msat: OptionalField::Present(40_000),
1990                         fee_base_msat: 0,
1991                         fee_proportional_millionths: 0,
1992                         excess_data: Vec::new()
1993                 });
1994
1995                 // Make 0 fee.
1996                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1997                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1998                         short_channel_id: 13,
1999                         timestamp: 2,
2000                         flags: 0,
2001                         cltv_expiry_delta: 0,
2002                         htlc_minimum_msat: 0,
2003                         htlc_maximum_msat: OptionalField::Absent,
2004                         fee_base_msat: 0,
2005                         fee_proportional_millionths: 0,
2006                         excess_data: Vec::new()
2007                 });
2008                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2009                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2010                         short_channel_id: 4,
2011                         timestamp: 2,
2012                         flags: 0,
2013                         cltv_expiry_delta: 0,
2014                         htlc_minimum_msat: 0,
2015                         htlc_maximum_msat: OptionalField::Absent,
2016                         fee_base_msat: 0,
2017                         fee_proportional_millionths: 0,
2018                         excess_data: Vec::new()
2019                 });
2020
2021                 // Disable other paths
2022                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2023                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2024                         short_channel_id: 1,
2025                         timestamp: 3,
2026                         flags: 2, // to disable
2027                         cltv_expiry_delta: 0,
2028                         htlc_minimum_msat: 0,
2029                         htlc_maximum_msat: OptionalField::Absent,
2030                         fee_base_msat: 0,
2031                         fee_proportional_millionths: 0,
2032                         excess_data: Vec::new()
2033                 });
2034
2035                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
2036                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger), &scorer).unwrap();
2037                 // Overpay fees to hit htlc_minimum_msat.
2038                 let overpaid_fees = route.paths[0][0].fee_msat + route.paths[1][0].fee_msat;
2039                 // TODO: this could be better balanced to overpay 10k and not 15k.
2040                 assert_eq!(overpaid_fees, 15_000);
2041
2042                 // Now, test that if there are 2 paths, a "cheaper" by fee path wouldn't be prioritized
2043                 // while taking even more fee to match htlc_minimum_msat.
2044                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2045                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2046                         short_channel_id: 12,
2047                         timestamp: 4,
2048                         flags: 0,
2049                         cltv_expiry_delta: 0,
2050                         htlc_minimum_msat: 65_000,
2051                         htlc_maximum_msat: OptionalField::Present(80_000),
2052                         fee_base_msat: 0,
2053                         fee_proportional_millionths: 0,
2054                         excess_data: Vec::new()
2055                 });
2056                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2057                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2058                         short_channel_id: 2,
2059                         timestamp: 3,
2060                         flags: 0,
2061                         cltv_expiry_delta: 0,
2062                         htlc_minimum_msat: 0,
2063                         htlc_maximum_msat: OptionalField::Absent,
2064                         fee_base_msat: 0,
2065                         fee_proportional_millionths: 0,
2066                         excess_data: Vec::new()
2067                 });
2068                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2069                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2070                         short_channel_id: 4,
2071                         timestamp: 4,
2072                         flags: 0,
2073                         cltv_expiry_delta: 0,
2074                         htlc_minimum_msat: 0,
2075                         htlc_maximum_msat: OptionalField::Absent,
2076                         fee_base_msat: 0,
2077                         fee_proportional_millionths: 100_000,
2078                         excess_data: Vec::new()
2079                 });
2080
2081                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
2082                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger), &scorer).unwrap();
2083                 // Fine to overpay for htlc_minimum_msat if it allows us to save fee.
2084                 assert_eq!(route.paths.len(), 1);
2085                 assert_eq!(route.paths[0][0].short_channel_id, 12);
2086                 let fees = route.paths[0][0].fee_msat;
2087                 assert_eq!(fees, 5_000);
2088
2089                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
2090                         Some(InvoiceFeatures::known()), None, &Vec::new(), 50_000, 42, Arc::clone(&logger), &scorer).unwrap();
2091                 // Not fine to overpay for htlc_minimum_msat if it requires paying more than fee on
2092                 // the other channel.
2093                 assert_eq!(route.paths.len(), 1);
2094                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2095                 let fees = route.paths[0][0].fee_msat;
2096                 assert_eq!(fees, 5_000);
2097         }
2098
2099         #[test]
2100         fn disable_channels_test() {
2101                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2102                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2103                 let scorer = Scorer::new(0);
2104
2105                 // // Disable channels 4 and 12 by flags=2
2106                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2107                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2108                         short_channel_id: 4,
2109                         timestamp: 2,
2110                         flags: 2, // to disable
2111                         cltv_expiry_delta: 0,
2112                         htlc_minimum_msat: 0,
2113                         htlc_maximum_msat: OptionalField::Absent,
2114                         fee_base_msat: 0,
2115                         fee_proportional_millionths: 0,
2116                         excess_data: Vec::new()
2117                 });
2118                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2119                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2120                         short_channel_id: 12,
2121                         timestamp: 2,
2122                         flags: 2, // to disable
2123                         cltv_expiry_delta: 0,
2124                         htlc_minimum_msat: 0,
2125                         htlc_maximum_msat: OptionalField::Absent,
2126                         fee_base_msat: 0,
2127                         fee_proportional_millionths: 0,
2128                         excess_data: Vec::new()
2129                 });
2130
2131                 // If all the channels require some features we don't understand, route should fail
2132                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger), &scorer) {
2133                         assert_eq!(err, "Failed to find a path to the given destination");
2134                 } else { panic!(); }
2135
2136                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2137                 let our_chans = vec![get_channel_details(Some(42), nodes[7].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2138                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()),  &Vec::new(), 100, 42, Arc::clone(&logger), &scorer).unwrap();
2139                 assert_eq!(route.paths[0].len(), 2);
2140
2141                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2142                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2143                 assert_eq!(route.paths[0][0].fee_msat, 200);
2144                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2145                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
2146                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2147
2148                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2149                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2150                 assert_eq!(route.paths[0][1].fee_msat, 100);
2151                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2152                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2153                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2154         }
2155
2156         #[test]
2157         fn disable_node_test() {
2158                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2159                 let (_, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2160                 let scorer = Scorer::new(0);
2161
2162                 // Disable nodes 1, 2, and 8 by requiring unknown feature bits
2163                 let unknown_features = NodeFeatures::known().set_unknown_feature_required();
2164                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], unknown_features.clone(), 1);
2165                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], unknown_features.clone(), 1);
2166                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], unknown_features.clone(), 1);
2167
2168                 // If all nodes require some features we don't understand, route should fail
2169                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger), &scorer) {
2170                         assert_eq!(err, "Failed to find a path to the given destination");
2171                 } else { panic!(); }
2172
2173                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2174                 let our_chans = vec![get_channel_details(Some(42), nodes[7].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2175                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger), &scorer).unwrap();
2176                 assert_eq!(route.paths[0].len(), 2);
2177
2178                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2179                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2180                 assert_eq!(route.paths[0][0].fee_msat, 200);
2181                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2182                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
2183                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2184
2185                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2186                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2187                 assert_eq!(route.paths[0][1].fee_msat, 100);
2188                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2189                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2190                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2191
2192                 // Note that we don't test disabling node 3 and failing to route to it, as we (somewhat
2193                 // naively) assume that the user checked the feature bits on the invoice, which override
2194                 // the node_announcement.
2195         }
2196
2197         #[test]
2198         fn our_chans_test() {
2199                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2200                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2201                 let scorer = Scorer::new(0);
2202
2203                 // Route to 1 via 2 and 3 because our channel to 1 is disabled
2204                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[0], None, None, &Vec::new(), 100, 42, Arc::clone(&logger), &scorer).unwrap();
2205                 assert_eq!(route.paths[0].len(), 3);
2206
2207                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2208                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2209                 assert_eq!(route.paths[0][0].fee_msat, 200);
2210                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2211                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2212                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2213
2214                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2215                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2216                 assert_eq!(route.paths[0][1].fee_msat, 100);
2217                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (3 << 8) | 2);
2218                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2219                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2220
2221                 assert_eq!(route.paths[0][2].pubkey, nodes[0]);
2222                 assert_eq!(route.paths[0][2].short_channel_id, 3);
2223                 assert_eq!(route.paths[0][2].fee_msat, 100);
2224                 assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
2225                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(1));
2226                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(3));
2227
2228                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2229                 let our_chans = vec![get_channel_details(Some(42), nodes[7].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2230                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger), &scorer).unwrap();
2231                 assert_eq!(route.paths[0].len(), 2);
2232
2233                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2234                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2235                 assert_eq!(route.paths[0][0].fee_msat, 200);
2236                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2237                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2238                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2239
2240                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2241                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2242                 assert_eq!(route.paths[0][1].fee_msat, 100);
2243                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2244                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2245                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2246         }
2247
2248         fn last_hops(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2249                 let zero_fees = RoutingFees {
2250                         base_msat: 0,
2251                         proportional_millionths: 0,
2252                 };
2253                 vec![RouteHint(vec![RouteHintHop {
2254                         src_node_id: nodes[3],
2255                         short_channel_id: 8,
2256                         fees: zero_fees,
2257                         cltv_expiry_delta: (8 << 8) | 1,
2258                         htlc_minimum_msat: None,
2259                         htlc_maximum_msat: None,
2260                 }
2261                 ]), RouteHint(vec![RouteHintHop {
2262                         src_node_id: nodes[4],
2263                         short_channel_id: 9,
2264                         fees: RoutingFees {
2265                                 base_msat: 1001,
2266                                 proportional_millionths: 0,
2267                         },
2268                         cltv_expiry_delta: (9 << 8) | 1,
2269                         htlc_minimum_msat: None,
2270                         htlc_maximum_msat: None,
2271                 }]), RouteHint(vec![RouteHintHop {
2272                         src_node_id: nodes[5],
2273                         short_channel_id: 10,
2274                         fees: zero_fees,
2275                         cltv_expiry_delta: (10 << 8) | 1,
2276                         htlc_minimum_msat: None,
2277                         htlc_maximum_msat: None,
2278                 }])]
2279         }
2280
2281         fn last_hops_multi_private_channels(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2282                 let zero_fees = RoutingFees {
2283                         base_msat: 0,
2284                         proportional_millionths: 0,
2285                 };
2286                 vec![RouteHint(vec![RouteHintHop {
2287                         src_node_id: nodes[2],
2288                         short_channel_id: 5,
2289                         fees: RoutingFees {
2290                                 base_msat: 100,
2291                                 proportional_millionths: 0,
2292                         },
2293                         cltv_expiry_delta: (5 << 8) | 1,
2294                         htlc_minimum_msat: None,
2295                         htlc_maximum_msat: None,
2296                 }, RouteHintHop {
2297                         src_node_id: nodes[3],
2298                         short_channel_id: 8,
2299                         fees: zero_fees,
2300                         cltv_expiry_delta: (8 << 8) | 1,
2301                         htlc_minimum_msat: None,
2302                         htlc_maximum_msat: None,
2303                 }
2304                 ]), RouteHint(vec![RouteHintHop {
2305                         src_node_id: nodes[4],
2306                         short_channel_id: 9,
2307                         fees: RoutingFees {
2308                                 base_msat: 1001,
2309                                 proportional_millionths: 0,
2310                         },
2311                         cltv_expiry_delta: (9 << 8) | 1,
2312                         htlc_minimum_msat: None,
2313                         htlc_maximum_msat: None,
2314                 }]), RouteHint(vec![RouteHintHop {
2315                         src_node_id: nodes[5],
2316                         short_channel_id: 10,
2317                         fees: zero_fees,
2318                         cltv_expiry_delta: (10 << 8) | 1,
2319                         htlc_minimum_msat: None,
2320                         htlc_maximum_msat: None,
2321                 }])]
2322         }
2323
2324         #[test]
2325         fn partial_route_hint_test() {
2326                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2327                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2328                 let scorer = Scorer::new(0);
2329
2330                 // Simple test across 2, 3, 5, and 4 via a last_hop channel
2331                 // Tests the behaviour when the RouteHint contains a suboptimal hop.
2332                 // RouteHint may be partially used by the algo to build the best path.
2333
2334                 // First check that last hop can't have its source as the payee.
2335                 let invalid_last_hop = RouteHint(vec![RouteHintHop {
2336                         src_node_id: nodes[6],
2337                         short_channel_id: 8,
2338                         fees: RoutingFees {
2339                                 base_msat: 1000,
2340                                 proportional_millionths: 0,
2341                         },
2342                         cltv_expiry_delta: (8 << 8) | 1,
2343                         htlc_minimum_msat: None,
2344                         htlc_maximum_msat: None,
2345                 }]);
2346
2347                 let mut invalid_last_hops = last_hops_multi_private_channels(&nodes);
2348                 invalid_last_hops.push(invalid_last_hop);
2349                 {
2350                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, None, &invalid_last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger), &scorer) {
2351                                 assert_eq!(err, "Last hop cannot have a payee as a source.");
2352                         } else { panic!(); }
2353                 }
2354
2355                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, None, &last_hops_multi_private_channels(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger), &scorer).unwrap();
2356                 assert_eq!(route.paths[0].len(), 5);
2357
2358                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2359                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2360                 assert_eq!(route.paths[0][0].fee_msat, 100);
2361                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2362                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2363                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2364
2365                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2366                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2367                 assert_eq!(route.paths[0][1].fee_msat, 0);
2368                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2369                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2370                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2371
2372                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2373                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2374                 assert_eq!(route.paths[0][2].fee_msat, 0);
2375                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2376                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2377                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2378
2379                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2380                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2381                 assert_eq!(route.paths[0][3].fee_msat, 0);
2382                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2383                 // If we have a peer in the node map, we'll use their features here since we don't have
2384                 // a way of figuring out their features from the invoice:
2385                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2386                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2387
2388                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2389                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2390                 assert_eq!(route.paths[0][4].fee_msat, 100);
2391                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2392                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2393                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2394         }
2395
2396         fn empty_last_hop(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2397                 let zero_fees = RoutingFees {
2398                         base_msat: 0,
2399                         proportional_millionths: 0,
2400                 };
2401                 vec![RouteHint(vec![RouteHintHop {
2402                         src_node_id: nodes[3],
2403                         short_channel_id: 8,
2404                         fees: zero_fees,
2405                         cltv_expiry_delta: (8 << 8) | 1,
2406                         htlc_minimum_msat: None,
2407                         htlc_maximum_msat: None,
2408                 }]), RouteHint(vec![
2409
2410                 ]), RouteHint(vec![RouteHintHop {
2411                         src_node_id: nodes[5],
2412                         short_channel_id: 10,
2413                         fees: zero_fees,
2414                         cltv_expiry_delta: (10 << 8) | 1,
2415                         htlc_minimum_msat: None,
2416                         htlc_maximum_msat: None,
2417                 }])]
2418         }
2419
2420         #[test]
2421         fn ignores_empty_last_hops_test() {
2422                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2423                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2424                 let scorer = Scorer::new(0);
2425
2426                 // Test handling of an empty RouteHint passed in Invoice.
2427
2428                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, None, &empty_last_hop(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger), &scorer).unwrap();
2429                 assert_eq!(route.paths[0].len(), 5);
2430
2431                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2432                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2433                 assert_eq!(route.paths[0][0].fee_msat, 100);
2434                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2435                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2436                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2437
2438                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2439                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2440                 assert_eq!(route.paths[0][1].fee_msat, 0);
2441                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2442                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2443                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2444
2445                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2446                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2447                 assert_eq!(route.paths[0][2].fee_msat, 0);
2448                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2449                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2450                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2451
2452                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2453                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2454                 assert_eq!(route.paths[0][3].fee_msat, 0);
2455                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2456                 // If we have a peer in the node map, we'll use their features here since we don't have
2457                 // a way of figuring out their features from the invoice:
2458                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2459                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2460
2461                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2462                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2463                 assert_eq!(route.paths[0][4].fee_msat, 100);
2464                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2465                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2466                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2467         }
2468
2469         fn multi_hint_last_hops(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2470                 let zero_fees = RoutingFees {
2471                         base_msat: 0,
2472                         proportional_millionths: 0,
2473                 };
2474                 vec![RouteHint(vec![RouteHintHop {
2475                         src_node_id: nodes[2],
2476                         short_channel_id: 5,
2477                         fees: RoutingFees {
2478                                 base_msat: 100,
2479                                 proportional_millionths: 0,
2480                         },
2481                         cltv_expiry_delta: (5 << 8) | 1,
2482                         htlc_minimum_msat: None,
2483                         htlc_maximum_msat: None,
2484                 }, RouteHintHop {
2485                         src_node_id: nodes[3],
2486                         short_channel_id: 8,
2487                         fees: zero_fees,
2488                         cltv_expiry_delta: (8 << 8) | 1,
2489                         htlc_minimum_msat: None,
2490                         htlc_maximum_msat: None,
2491                 }]), RouteHint(vec![RouteHintHop {
2492                         src_node_id: nodes[5],
2493                         short_channel_id: 10,
2494                         fees: zero_fees,
2495                         cltv_expiry_delta: (10 << 8) | 1,
2496                         htlc_minimum_msat: None,
2497                         htlc_maximum_msat: None,
2498                 }])]
2499         }
2500
2501         #[test]
2502         fn multi_hint_last_hops_test() {
2503                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2504                 let (_, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2505                 let scorer = Scorer::new(0);
2506                 // Test through channels 2, 3, 5, 8.
2507                 // Test shows that multiple hop hints are considered.
2508
2509                 // Disabling channels 6 & 7 by flags=2
2510                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2511                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2512                         short_channel_id: 6,
2513                         timestamp: 2,
2514                         flags: 2, // to disable
2515                         cltv_expiry_delta: 0,
2516                         htlc_minimum_msat: 0,
2517                         htlc_maximum_msat: OptionalField::Absent,
2518                         fee_base_msat: 0,
2519                         fee_proportional_millionths: 0,
2520                         excess_data: Vec::new()
2521                 });
2522                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2523                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2524                         short_channel_id: 7,
2525                         timestamp: 2,
2526                         flags: 2, // to disable
2527                         cltv_expiry_delta: 0,
2528                         htlc_minimum_msat: 0,
2529                         htlc_maximum_msat: OptionalField::Absent,
2530                         fee_base_msat: 0,
2531                         fee_proportional_millionths: 0,
2532                         excess_data: Vec::new()
2533                 });
2534
2535                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, None, &multi_hint_last_hops(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger), &scorer).unwrap();
2536                 assert_eq!(route.paths[0].len(), 4);
2537
2538                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2539                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2540                 assert_eq!(route.paths[0][0].fee_msat, 200);
2541                 assert_eq!(route.paths[0][0].cltv_expiry_delta, 1025);
2542                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2543                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2544
2545                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2546                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2547                 assert_eq!(route.paths[0][1].fee_msat, 100);
2548                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 1281);
2549                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2550                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2551
2552                 assert_eq!(route.paths[0][2].pubkey, nodes[3]);
2553                 assert_eq!(route.paths[0][2].short_channel_id, 5);
2554                 assert_eq!(route.paths[0][2].fee_msat, 0);
2555                 assert_eq!(route.paths[0][2].cltv_expiry_delta, 2049);
2556                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(4));
2557                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &Vec::<u8>::new());
2558
2559                 assert_eq!(route.paths[0][3].pubkey, nodes[6]);
2560                 assert_eq!(route.paths[0][3].short_channel_id, 8);
2561                 assert_eq!(route.paths[0][3].fee_msat, 100);
2562                 assert_eq!(route.paths[0][3].cltv_expiry_delta, 42);
2563                 assert_eq!(route.paths[0][3].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2564                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2565         }
2566
2567         fn last_hops_with_public_channel(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2568                 let zero_fees = RoutingFees {
2569                         base_msat: 0,
2570                         proportional_millionths: 0,
2571                 };
2572                 vec![RouteHint(vec![RouteHintHop {
2573                         src_node_id: nodes[4],
2574                         short_channel_id: 11,
2575                         fees: zero_fees,
2576                         cltv_expiry_delta: (11 << 8) | 1,
2577                         htlc_minimum_msat: None,
2578                         htlc_maximum_msat: None,
2579                 }, RouteHintHop {
2580                         src_node_id: nodes[3],
2581                         short_channel_id: 8,
2582                         fees: zero_fees,
2583                         cltv_expiry_delta: (8 << 8) | 1,
2584                         htlc_minimum_msat: None,
2585                         htlc_maximum_msat: None,
2586                 }]), RouteHint(vec![RouteHintHop {
2587                         src_node_id: nodes[4],
2588                         short_channel_id: 9,
2589                         fees: RoutingFees {
2590                                 base_msat: 1001,
2591                                 proportional_millionths: 0,
2592                         },
2593                         cltv_expiry_delta: (9 << 8) | 1,
2594                         htlc_minimum_msat: None,
2595                         htlc_maximum_msat: None,
2596                 }]), RouteHint(vec![RouteHintHop {
2597                         src_node_id: nodes[5],
2598                         short_channel_id: 10,
2599                         fees: zero_fees,
2600                         cltv_expiry_delta: (10 << 8) | 1,
2601                         htlc_minimum_msat: None,
2602                         htlc_maximum_msat: None,
2603                 }])]
2604         }
2605
2606         #[test]
2607         fn last_hops_with_public_channel_test() {
2608                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2609                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2610                 let scorer = Scorer::new(0);
2611                 // This test shows that public routes can be present in the invoice
2612                 // which would be handled in the same manner.
2613
2614                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, None, &last_hops_with_public_channel(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger), &scorer).unwrap();
2615                 assert_eq!(route.paths[0].len(), 5);
2616
2617                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2618                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2619                 assert_eq!(route.paths[0][0].fee_msat, 100);
2620                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2621                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2622                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2623
2624                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2625                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2626                 assert_eq!(route.paths[0][1].fee_msat, 0);
2627                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2628                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2629                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2630
2631                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2632                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2633                 assert_eq!(route.paths[0][2].fee_msat, 0);
2634                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2635                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2636                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2637
2638                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2639                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2640                 assert_eq!(route.paths[0][3].fee_msat, 0);
2641                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2642                 // If we have a peer in the node map, we'll use their features here since we don't have
2643                 // a way of figuring out their features from the invoice:
2644                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2645                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new());
2646
2647                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2648                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2649                 assert_eq!(route.paths[0][4].fee_msat, 100);
2650                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2651                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2652                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2653         }
2654
2655         #[test]
2656         fn our_chans_last_hop_connect_test() {
2657                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2658                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2659                 let scorer = Scorer::new(0);
2660
2661                 // Simple test with outbound channel to 4 to test that last_hops and first_hops connect
2662                 let our_chans = vec![get_channel_details(Some(42), nodes[3].clone(), InitFeatures::from_le_bytes(vec![0b11]), 250_000_000)];
2663                 let mut last_hops = last_hops(&nodes);
2664                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, Some(&our_chans.iter().collect::<Vec<_>>()), &last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger), &scorer).unwrap();
2665                 assert_eq!(route.paths[0].len(), 2);
2666
2667                 assert_eq!(route.paths[0][0].pubkey, nodes[3]);
2668                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2669                 assert_eq!(route.paths[0][0].fee_msat, 0);
2670                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2671                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2672                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2673
2674                 assert_eq!(route.paths[0][1].pubkey, nodes[6]);
2675                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2676                 assert_eq!(route.paths[0][1].fee_msat, 100);
2677                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2678                 assert_eq!(route.paths[0][1].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2679                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2680
2681                 last_hops[0].0[0].fees.base_msat = 1000;
2682
2683                 // Revert to via 6 as the fee on 8 goes up
2684                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, None, &last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger), &scorer).unwrap();
2685                 assert_eq!(route.paths[0].len(), 4);
2686
2687                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2688                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2689                 assert_eq!(route.paths[0][0].fee_msat, 200); // fee increased as its % of value transferred across node
2690                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2691                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2692                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2693
2694                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2695                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2696                 assert_eq!(route.paths[0][1].fee_msat, 100);
2697                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (7 << 8) | 1);
2698                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2699                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2700
2701                 assert_eq!(route.paths[0][2].pubkey, nodes[5]);
2702                 assert_eq!(route.paths[0][2].short_channel_id, 7);
2703                 assert_eq!(route.paths[0][2].fee_msat, 0);
2704                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (10 << 8) | 1);
2705                 // If we have a peer in the node map, we'll use their features here since we don't have
2706                 // a way of figuring out their features from the invoice:
2707                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
2708                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(7));
2709
2710                 assert_eq!(route.paths[0][3].pubkey, nodes[6]);
2711                 assert_eq!(route.paths[0][3].short_channel_id, 10);
2712                 assert_eq!(route.paths[0][3].fee_msat, 100);
2713                 assert_eq!(route.paths[0][3].cltv_expiry_delta, 42);
2714                 assert_eq!(route.paths[0][3].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2715                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2716
2717                 // ...but still use 8 for larger payments as 6 has a variable feerate
2718                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, None, &last_hops.iter().collect::<Vec<_>>(), 2000, 42, Arc::clone(&logger), &scorer).unwrap();
2719                 assert_eq!(route.paths[0].len(), 5);
2720
2721                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2722                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2723                 assert_eq!(route.paths[0][0].fee_msat, 3000);
2724                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2725                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2726                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2727
2728                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2729                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2730                 assert_eq!(route.paths[0][1].fee_msat, 0);
2731                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2732                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2733                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2734
2735                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2736                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2737                 assert_eq!(route.paths[0][2].fee_msat, 0);
2738                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2739                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2740                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2741
2742                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2743                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2744                 assert_eq!(route.paths[0][3].fee_msat, 1000);
2745                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2746                 // If we have a peer in the node map, we'll use their features here since we don't have
2747                 // a way of figuring out their features from the invoice:
2748                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2749                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2750
2751                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2752                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2753                 assert_eq!(route.paths[0][4].fee_msat, 2000);
2754                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2755                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2756                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2757         }
2758
2759         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> {
2760                 let source_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 41).repeat(32)).unwrap()[..]).unwrap());
2761                 let middle_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 42).repeat(32)).unwrap()[..]).unwrap());
2762                 let target_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 43).repeat(32)).unwrap()[..]).unwrap());
2763
2764                 // If we specify a channel to a middle hop, that overrides our local channel view and that gets used
2765                 let last_hops = RouteHint(vec![RouteHintHop {
2766                         src_node_id: middle_node_id,
2767                         short_channel_id: 8,
2768                         fees: RoutingFees {
2769                                 base_msat: 1000,
2770                                 proportional_millionths: last_hop_fee_prop,
2771                         },
2772                         cltv_expiry_delta: (8 << 8) | 1,
2773                         htlc_minimum_msat: None,
2774                         htlc_maximum_msat: last_hop_htlc_max,
2775                 }]);
2776                 let our_chans = vec![get_channel_details(Some(42), middle_node_id, InitFeatures::from_le_bytes(vec![0b11]), outbound_capacity_msat)];
2777                 let scorer = Scorer::new(0);
2778                 get_route(&source_node_id, &NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash()), &target_node_id, None, Some(&our_chans.iter().collect::<Vec<_>>()), &vec![&last_hops], route_val, 42, &test_utils::TestLogger::new(), &scorer)
2779         }
2780
2781         #[test]
2782         fn unannounced_path_test() {
2783                 // We should be able to send a payment to a destination without any help of a routing graph
2784                 // if we have a channel with a common counterparty that appears in the first and last hop
2785                 // hints.
2786                 let route = do_unannounced_path_test(None, 1, 2000000, 1000000).unwrap();
2787
2788                 let middle_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 42).repeat(32)).unwrap()[..]).unwrap());
2789                 let target_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 43).repeat(32)).unwrap()[..]).unwrap());
2790                 assert_eq!(route.paths[0].len(), 2);
2791
2792                 assert_eq!(route.paths[0][0].pubkey, middle_node_id);
2793                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2794                 assert_eq!(route.paths[0][0].fee_msat, 1001);
2795                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2796                 assert_eq!(route.paths[0][0].node_features.le_flags(), &[0b11]);
2797                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2798
2799                 assert_eq!(route.paths[0][1].pubkey, target_node_id);
2800                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2801                 assert_eq!(route.paths[0][1].fee_msat, 1000000);
2802                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2803                 assert_eq!(route.paths[0][1].node_features.le_flags(), &[0; 0]); // We dont pass flags in from invoices yet
2804                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2805         }
2806
2807         #[test]
2808         fn overflow_unannounced_path_test_liquidity_underflow() {
2809                 // Previously, when we had a last-hop hint connected directly to a first-hop channel, where
2810                 // the last-hop had a fee which overflowed a u64, we'd panic.
2811                 // This was due to us adding the first-hop from us unconditionally, causing us to think
2812                 // we'd built a path (as our node is in the "best candidate" set), when we had not.
2813                 // In this test, we previously hit a subtraction underflow due to having less available
2814                 // liquidity at the last hop than 0.
2815                 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());
2816         }
2817
2818         #[test]
2819         fn overflow_unannounced_path_test_feerate_overflow() {
2820                 // This tests for the same case as above, except instead of hitting a subtraction
2821                 // underflow, we hit a case where the fee charged at a hop overflowed.
2822                 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());
2823         }
2824
2825         #[test]
2826         fn available_amount_while_routing_test() {
2827                 // Tests whether we choose the correct available channel amount while routing.
2828
2829                 let (secp_ctx, mut net_graph_msg_handler, chain_monitor, logger) = build_graph();
2830                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2831                 let scorer = Scorer::new(0);
2832
2833                 // We will use a simple single-path route from
2834                 // our node to node2 via node0: channels {1, 3}.
2835
2836                 // First disable all other paths.
2837                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2838                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2839                         short_channel_id: 2,
2840                         timestamp: 2,
2841                         flags: 2,
2842                         cltv_expiry_delta: 0,
2843                         htlc_minimum_msat: 0,
2844                         htlc_maximum_msat: OptionalField::Present(100_000),
2845                         fee_base_msat: 0,
2846                         fee_proportional_millionths: 0,
2847                         excess_data: Vec::new()
2848                 });
2849                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2850                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2851                         short_channel_id: 12,
2852                         timestamp: 2,
2853                         flags: 2,
2854                         cltv_expiry_delta: 0,
2855                         htlc_minimum_msat: 0,
2856                         htlc_maximum_msat: OptionalField::Present(100_000),
2857                         fee_base_msat: 0,
2858                         fee_proportional_millionths: 0,
2859                         excess_data: Vec::new()
2860                 });
2861
2862                 // Make the first channel (#1) very permissive,
2863                 // and we will be testing all limits on the second channel.
2864                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2865                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2866                         short_channel_id: 1,
2867                         timestamp: 2,
2868                         flags: 0,
2869                         cltv_expiry_delta: 0,
2870                         htlc_minimum_msat: 0,
2871                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2872                         fee_base_msat: 0,
2873                         fee_proportional_millionths: 0,
2874                         excess_data: Vec::new()
2875                 });
2876
2877                 // First, let's see if routing works if we have absolutely no idea about the available amount.
2878                 // In this case, it should be set to 250_000 sats.
2879                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2880                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2881                         short_channel_id: 3,
2882                         timestamp: 2,
2883                         flags: 0,
2884                         cltv_expiry_delta: 0,
2885                         htlc_minimum_msat: 0,
2886                         htlc_maximum_msat: OptionalField::Absent,
2887                         fee_base_msat: 0,
2888                         fee_proportional_millionths: 0,
2889                         excess_data: Vec::new()
2890                 });
2891
2892                 {
2893                         // Attempt to route more than available results in a failure.
2894                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
2895                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000_001, 42, Arc::clone(&logger), &scorer) {
2896                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2897                         } else { panic!(); }
2898                 }
2899
2900                 {
2901                         // Now, attempt to route an exact amount we have should be fine.
2902                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
2903                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000_000, 42, Arc::clone(&logger), &scorer).unwrap();
2904                         assert_eq!(route.paths.len(), 1);
2905                         let path = route.paths.last().unwrap();
2906                         assert_eq!(path.len(), 2);
2907                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2908                         assert_eq!(path.last().unwrap().fee_msat, 250_000_000);
2909                 }
2910
2911                 // Check that setting outbound_capacity_msat in first_hops limits the channels.
2912                 // Disable channel #1 and use another first hop.
2913                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2914                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2915                         short_channel_id: 1,
2916                         timestamp: 3,
2917                         flags: 2,
2918                         cltv_expiry_delta: 0,
2919                         htlc_minimum_msat: 0,
2920                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2921                         fee_base_msat: 0,
2922                         fee_proportional_millionths: 0,
2923                         excess_data: Vec::new()
2924                 });
2925
2926                 // Now, limit the first_hop by the outbound_capacity_msat of 200_000 sats.
2927                 let our_chans = vec![get_channel_details(Some(42), nodes[0].clone(), InitFeatures::from_le_bytes(vec![0b11]), 200_000_000)];
2928
2929                 {
2930                         // Attempt to route more than available results in a failure.
2931                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
2932                                         Some(InvoiceFeatures::known()), Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_001, 42, Arc::clone(&logger), &scorer) {
2933                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2934                         } else { panic!(); }
2935                 }
2936
2937                 {
2938                         // Now, attempt to route an exact amount we have should be fine.
2939                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
2940                                 Some(InvoiceFeatures::known()), Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_000, 42, Arc::clone(&logger), &scorer).unwrap();
2941                         assert_eq!(route.paths.len(), 1);
2942                         let path = route.paths.last().unwrap();
2943                         assert_eq!(path.len(), 2);
2944                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2945                         assert_eq!(path.last().unwrap().fee_msat, 200_000_000);
2946                 }
2947
2948                 // Enable channel #1 back.
2949                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2950                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2951                         short_channel_id: 1,
2952                         timestamp: 4,
2953                         flags: 0,
2954                         cltv_expiry_delta: 0,
2955                         htlc_minimum_msat: 0,
2956                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2957                         fee_base_msat: 0,
2958                         fee_proportional_millionths: 0,
2959                         excess_data: Vec::new()
2960                 });
2961
2962
2963                 // Now let's see if routing works if we know only htlc_maximum_msat.
2964                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2965                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2966                         short_channel_id: 3,
2967                         timestamp: 3,
2968                         flags: 0,
2969                         cltv_expiry_delta: 0,
2970                         htlc_minimum_msat: 0,
2971                         htlc_maximum_msat: OptionalField::Present(15_000),
2972                         fee_base_msat: 0,
2973                         fee_proportional_millionths: 0,
2974                         excess_data: Vec::new()
2975                 });
2976
2977                 {
2978                         // Attempt to route more than available results in a failure.
2979                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
2980                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 15_001, 42, Arc::clone(&logger), &scorer) {
2981                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2982                         } else { panic!(); }
2983                 }
2984
2985                 {
2986                         // Now, attempt to route an exact amount we have should be fine.
2987                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
2988                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 15_000, 42, Arc::clone(&logger), &scorer).unwrap();
2989                         assert_eq!(route.paths.len(), 1);
2990                         let path = route.paths.last().unwrap();
2991                         assert_eq!(path.len(), 2);
2992                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2993                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
2994                 }
2995
2996                 // Now let's see if routing works if we know only capacity from the UTXO.
2997
2998                 // We can't change UTXO capacity on the fly, so we'll disable
2999                 // the existing channel and add another one with the capacity we need.
3000                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3001                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3002                         short_channel_id: 3,
3003                         timestamp: 4,
3004                         flags: 2,
3005                         cltv_expiry_delta: 0,
3006                         htlc_minimum_msat: 0,
3007                         htlc_maximum_msat: OptionalField::Absent,
3008                         fee_base_msat: 0,
3009                         fee_proportional_millionths: 0,
3010                         excess_data: Vec::new()
3011                 });
3012
3013                 let good_script = Builder::new().push_opcode(opcodes::all::OP_PUSHNUM_2)
3014                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[0]).serialize())
3015                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[2]).serialize())
3016                 .push_opcode(opcodes::all::OP_PUSHNUM_2)
3017                 .push_opcode(opcodes::all::OP_CHECKMULTISIG).into_script().to_v0_p2wsh();
3018
3019                 *chain_monitor.utxo_ret.lock().unwrap() = Ok(TxOut { value: 15, script_pubkey: good_script.clone() });
3020                 net_graph_msg_handler.add_chain_access(Some(chain_monitor));
3021
3022                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 333);
3023                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3024                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3025                         short_channel_id: 333,
3026                         timestamp: 1,
3027                         flags: 0,
3028                         cltv_expiry_delta: (3 << 8) | 1,
3029                         htlc_minimum_msat: 0,
3030                         htlc_maximum_msat: OptionalField::Absent,
3031                         fee_base_msat: 0,
3032                         fee_proportional_millionths: 0,
3033                         excess_data: Vec::new()
3034                 });
3035                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3036                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3037                         short_channel_id: 333,
3038                         timestamp: 1,
3039                         flags: 1,
3040                         cltv_expiry_delta: (3 << 8) | 2,
3041                         htlc_minimum_msat: 0,
3042                         htlc_maximum_msat: OptionalField::Absent,
3043                         fee_base_msat: 100,
3044                         fee_proportional_millionths: 0,
3045                         excess_data: Vec::new()
3046                 });
3047
3048                 {
3049                         // Attempt to route more than available results in a failure.
3050                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
3051                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 15_001, 42, Arc::clone(&logger), &scorer) {
3052                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3053                         } else { panic!(); }
3054                 }
3055
3056                 {
3057                         // Now, attempt to route an exact amount we have should be fine.
3058                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
3059                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 15_000, 42, Arc::clone(&logger), &scorer).unwrap();
3060                         assert_eq!(route.paths.len(), 1);
3061                         let path = route.paths.last().unwrap();
3062                         assert_eq!(path.len(), 2);
3063                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3064                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
3065                 }
3066
3067                 // Now let's see if routing chooses htlc_maximum_msat over UTXO capacity.
3068                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3069                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3070                         short_channel_id: 333,
3071                         timestamp: 6,
3072                         flags: 0,
3073                         cltv_expiry_delta: 0,
3074                         htlc_minimum_msat: 0,
3075                         htlc_maximum_msat: OptionalField::Present(10_000),
3076                         fee_base_msat: 0,
3077                         fee_proportional_millionths: 0,
3078                         excess_data: Vec::new()
3079                 });
3080
3081                 {
3082                         // Attempt to route more than available results in a failure.
3083                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
3084                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 10_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, &net_graph_msg_handler.network_graph, &nodes[2],
3092                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 10_000, 42, Arc::clone(&logger), &scorer).unwrap();
3093                         assert_eq!(route.paths.len(), 1);
3094                         let path = route.paths.last().unwrap();
3095                         assert_eq!(path.len(), 2);
3096                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3097                         assert_eq!(path.last().unwrap().fee_msat, 10_000);
3098                 }
3099         }
3100
3101         #[test]
3102         fn available_liquidity_last_hop_test() {
3103                 // Check that available liquidity properly limits the path even when only
3104                 // one of the latter hops is limited.
3105                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3106                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3107                 let scorer = Scorer::new(0);
3108
3109                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3110                 // {12, 13, 11} have the capacities of 100, {6} has a capacity of 50.
3111                 // Total capacity: 50 sats.
3112
3113                 // Disable other potential paths.
3114                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3115                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3116                         short_channel_id: 2,
3117                         timestamp: 2,
3118                         flags: 2,
3119                         cltv_expiry_delta: 0,
3120                         htlc_minimum_msat: 0,
3121                         htlc_maximum_msat: OptionalField::Present(100_000),
3122                         fee_base_msat: 0,
3123                         fee_proportional_millionths: 0,
3124                         excess_data: Vec::new()
3125                 });
3126                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3127                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3128                         short_channel_id: 7,
3129                         timestamp: 2,
3130                         flags: 2,
3131                         cltv_expiry_delta: 0,
3132                         htlc_minimum_msat: 0,
3133                         htlc_maximum_msat: OptionalField::Present(100_000),
3134                         fee_base_msat: 0,
3135                         fee_proportional_millionths: 0,
3136                         excess_data: Vec::new()
3137                 });
3138
3139                 // Limit capacities
3140
3141                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3142                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3143                         short_channel_id: 12,
3144                         timestamp: 2,
3145                         flags: 0,
3146                         cltv_expiry_delta: 0,
3147                         htlc_minimum_msat: 0,
3148                         htlc_maximum_msat: OptionalField::Present(100_000),
3149                         fee_base_msat: 0,
3150                         fee_proportional_millionths: 0,
3151                         excess_data: Vec::new()
3152                 });
3153                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3154                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3155                         short_channel_id: 13,
3156                         timestamp: 2,
3157                         flags: 0,
3158                         cltv_expiry_delta: 0,
3159                         htlc_minimum_msat: 0,
3160                         htlc_maximum_msat: OptionalField::Present(100_000),
3161                         fee_base_msat: 0,
3162                         fee_proportional_millionths: 0,
3163                         excess_data: Vec::new()
3164                 });
3165
3166                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3167                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3168                         short_channel_id: 6,
3169                         timestamp: 2,
3170                         flags: 0,
3171                         cltv_expiry_delta: 0,
3172                         htlc_minimum_msat: 0,
3173                         htlc_maximum_msat: OptionalField::Present(50_000),
3174                         fee_base_msat: 0,
3175                         fee_proportional_millionths: 0,
3176                         excess_data: Vec::new()
3177                 });
3178                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3179                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3180                         short_channel_id: 11,
3181                         timestamp: 2,
3182                         flags: 0,
3183                         cltv_expiry_delta: 0,
3184                         htlc_minimum_msat: 0,
3185                         htlc_maximum_msat: OptionalField::Present(100_000),
3186                         fee_base_msat: 0,
3187                         fee_proportional_millionths: 0,
3188                         excess_data: Vec::new()
3189                 });
3190                 {
3191                         // Attempt to route more than available results in a failure.
3192                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[3],
3193                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger), &scorer) {
3194                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3195                         } else { panic!(); }
3196                 }
3197
3198                 {
3199                         // Now, attempt to route 49 sats (just a bit below the capacity).
3200                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[3],
3201                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 49_000, 42, Arc::clone(&logger), &scorer).unwrap();
3202                         assert_eq!(route.paths.len(), 1);
3203                         let mut total_amount_paid_msat = 0;
3204                         for path in &route.paths {
3205                                 assert_eq!(path.len(), 4);
3206                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3207                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3208                         }
3209                         assert_eq!(total_amount_paid_msat, 49_000);
3210                 }
3211
3212                 {
3213                         // Attempt to route an exact amount is also fine
3214                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[3],
3215                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 50_000, 42, Arc::clone(&logger), &scorer).unwrap();
3216                         assert_eq!(route.paths.len(), 1);
3217                         let mut total_amount_paid_msat = 0;
3218                         for path in &route.paths {
3219                                 assert_eq!(path.len(), 4);
3220                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3221                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3222                         }
3223                         assert_eq!(total_amount_paid_msat, 50_000);
3224                 }
3225         }
3226
3227         #[test]
3228         fn ignore_fee_first_hop_test() {
3229                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3230                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3231                 let scorer = Scorer::new(0);
3232
3233                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
3234                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3235                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3236                         short_channel_id: 1,
3237                         timestamp: 2,
3238                         flags: 0,
3239                         cltv_expiry_delta: 0,
3240                         htlc_minimum_msat: 0,
3241                         htlc_maximum_msat: OptionalField::Present(100_000),
3242                         fee_base_msat: 1_000_000,
3243                         fee_proportional_millionths: 0,
3244                         excess_data: Vec::new()
3245                 });
3246                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3247                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3248                         short_channel_id: 3,
3249                         timestamp: 2,
3250                         flags: 0,
3251                         cltv_expiry_delta: 0,
3252                         htlc_minimum_msat: 0,
3253                         htlc_maximum_msat: OptionalField::Present(50_000),
3254                         fee_base_msat: 0,
3255                         fee_proportional_millionths: 0,
3256                         excess_data: Vec::new()
3257                 });
3258
3259                 {
3260                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, None, &Vec::new(), 50_000, 42, Arc::clone(&logger), &scorer).unwrap();
3261                         assert_eq!(route.paths.len(), 1);
3262                         let mut total_amount_paid_msat = 0;
3263                         for path in &route.paths {
3264                                 assert_eq!(path.len(), 2);
3265                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3266                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3267                         }
3268                         assert_eq!(total_amount_paid_msat, 50_000);
3269                 }
3270         }
3271
3272         #[test]
3273         fn simple_mpp_route_test() {
3274                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3275                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3276                 let scorer = Scorer::new(0);
3277
3278                 // We need a route consisting of 3 paths:
3279                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
3280                 // To achieve this, the amount being transferred should be around
3281                 // the total capacity of these 3 paths.
3282
3283                 // First, we set limits on these (previously unlimited) channels.
3284                 // Their aggregate capacity will be 50 + 60 + 180 = 290 sats.
3285
3286                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
3287                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3288                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3289                         short_channel_id: 1,
3290                         timestamp: 2,
3291                         flags: 0,
3292                         cltv_expiry_delta: 0,
3293                         htlc_minimum_msat: 0,
3294                         htlc_maximum_msat: OptionalField::Present(100_000),
3295                         fee_base_msat: 0,
3296                         fee_proportional_millionths: 0,
3297                         excess_data: Vec::new()
3298                 });
3299                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3300                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3301                         short_channel_id: 3,
3302                         timestamp: 2,
3303                         flags: 0,
3304                         cltv_expiry_delta: 0,
3305                         htlc_minimum_msat: 0,
3306                         htlc_maximum_msat: OptionalField::Present(50_000),
3307                         fee_base_msat: 0,
3308                         fee_proportional_millionths: 0,
3309                         excess_data: Vec::new()
3310                 });
3311
3312                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats
3313                 // (total limit 60).
3314                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3315                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3316                         short_channel_id: 12,
3317                         timestamp: 2,
3318                         flags: 0,
3319                         cltv_expiry_delta: 0,
3320                         htlc_minimum_msat: 0,
3321                         htlc_maximum_msat: OptionalField::Present(60_000),
3322                         fee_base_msat: 0,
3323                         fee_proportional_millionths: 0,
3324                         excess_data: Vec::new()
3325                 });
3326                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3327                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3328                         short_channel_id: 13,
3329                         timestamp: 2,
3330                         flags: 0,
3331                         cltv_expiry_delta: 0,
3332                         htlc_minimum_msat: 0,
3333                         htlc_maximum_msat: OptionalField::Present(60_000),
3334                         fee_base_msat: 0,
3335                         fee_proportional_millionths: 0,
3336                         excess_data: Vec::new()
3337                 });
3338
3339                 // Path via node1 is channels {2, 4}. Limit them to 200 and 180 sats
3340                 // (total capacity 180 sats).
3341                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3342                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3343                         short_channel_id: 2,
3344                         timestamp: 2,
3345                         flags: 0,
3346                         cltv_expiry_delta: 0,
3347                         htlc_minimum_msat: 0,
3348                         htlc_maximum_msat: OptionalField::Present(200_000),
3349                         fee_base_msat: 0,
3350                         fee_proportional_millionths: 0,
3351                         excess_data: Vec::new()
3352                 });
3353                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3354                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3355                         short_channel_id: 4,
3356                         timestamp: 2,
3357                         flags: 0,
3358                         cltv_expiry_delta: 0,
3359                         htlc_minimum_msat: 0,
3360                         htlc_maximum_msat: OptionalField::Present(180_000),
3361                         fee_base_msat: 0,
3362                         fee_proportional_millionths: 0,
3363                         excess_data: Vec::new()
3364                 });
3365
3366                 {
3367                         // Attempt to route more than available results in a failure.
3368                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph,
3369                                         &nodes[2], Some(InvoiceFeatures::known()), None, &Vec::new(), 300_000, 42, Arc::clone(&logger), &scorer) {
3370                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3371                         } else { panic!(); }
3372                 }
3373
3374                 {
3375                         // Now, attempt to route 250 sats (just a bit below the capacity).
3376                         // Our algorithm should provide us with these 3 paths.
3377                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
3378                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000, 42, Arc::clone(&logger), &scorer).unwrap();
3379                         assert_eq!(route.paths.len(), 3);
3380                         let mut total_amount_paid_msat = 0;
3381                         for path in &route.paths {
3382                                 assert_eq!(path.len(), 2);
3383                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3384                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3385                         }
3386                         assert_eq!(total_amount_paid_msat, 250_000);
3387                 }
3388
3389                 {
3390                         // Attempt to route an exact amount is also fine
3391                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
3392                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 290_000, 42, Arc::clone(&logger), &scorer).unwrap();
3393                         assert_eq!(route.paths.len(), 3);
3394                         let mut total_amount_paid_msat = 0;
3395                         for path in &route.paths {
3396                                 assert_eq!(path.len(), 2);
3397                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3398                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3399                         }
3400                         assert_eq!(total_amount_paid_msat, 290_000);
3401                 }
3402         }
3403
3404         #[test]
3405         fn long_mpp_route_test() {
3406                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3407                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3408                 let scorer = Scorer::new(0);
3409
3410                 // We need a route consisting of 3 paths:
3411                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
3412                 // Note that these paths overlap (channels 5, 12, 13).
3413                 // We will route 300 sats.
3414                 // Each path will have 100 sats capacity, those channels which
3415                 // are used twice will have 200 sats capacity.
3416
3417                 // Disable other potential paths.
3418                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3419                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3420                         short_channel_id: 2,
3421                         timestamp: 2,
3422                         flags: 2,
3423                         cltv_expiry_delta: 0,
3424                         htlc_minimum_msat: 0,
3425                         htlc_maximum_msat: OptionalField::Present(100_000),
3426                         fee_base_msat: 0,
3427                         fee_proportional_millionths: 0,
3428                         excess_data: Vec::new()
3429                 });
3430                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3431                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3432                         short_channel_id: 7,
3433                         timestamp: 2,
3434                         flags: 2,
3435                         cltv_expiry_delta: 0,
3436                         htlc_minimum_msat: 0,
3437                         htlc_maximum_msat: OptionalField::Present(100_000),
3438                         fee_base_msat: 0,
3439                         fee_proportional_millionths: 0,
3440                         excess_data: Vec::new()
3441                 });
3442
3443                 // Path via {node0, node2} is channels {1, 3, 5}.
3444                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3445                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3446                         short_channel_id: 1,
3447                         timestamp: 2,
3448                         flags: 0,
3449                         cltv_expiry_delta: 0,
3450                         htlc_minimum_msat: 0,
3451                         htlc_maximum_msat: OptionalField::Present(100_000),
3452                         fee_base_msat: 0,
3453                         fee_proportional_millionths: 0,
3454                         excess_data: Vec::new()
3455                 });
3456                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3457                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3458                         short_channel_id: 3,
3459                         timestamp: 2,
3460                         flags: 0,
3461                         cltv_expiry_delta: 0,
3462                         htlc_minimum_msat: 0,
3463                         htlc_maximum_msat: OptionalField::Present(100_000),
3464                         fee_base_msat: 0,
3465                         fee_proportional_millionths: 0,
3466                         excess_data: Vec::new()
3467                 });
3468
3469                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3470                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3471                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3472                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3473                         short_channel_id: 5,
3474                         timestamp: 2,
3475                         flags: 0,
3476                         cltv_expiry_delta: 0,
3477                         htlc_minimum_msat: 0,
3478                         htlc_maximum_msat: OptionalField::Present(200_000),
3479                         fee_base_msat: 0,
3480                         fee_proportional_millionths: 0,
3481                         excess_data: Vec::new()
3482                 });
3483
3484                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3485                 // Add 100 sats to the capacities of {12, 13}, because these channels
3486                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3487                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3488                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3489                         short_channel_id: 12,
3490                         timestamp: 2,
3491                         flags: 0,
3492                         cltv_expiry_delta: 0,
3493                         htlc_minimum_msat: 0,
3494                         htlc_maximum_msat: OptionalField::Present(200_000),
3495                         fee_base_msat: 0,
3496                         fee_proportional_millionths: 0,
3497                         excess_data: Vec::new()
3498                 });
3499                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3500                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3501                         short_channel_id: 13,
3502                         timestamp: 2,
3503                         flags: 0,
3504                         cltv_expiry_delta: 0,
3505                         htlc_minimum_msat: 0,
3506                         htlc_maximum_msat: OptionalField::Present(200_000),
3507                         fee_base_msat: 0,
3508                         fee_proportional_millionths: 0,
3509                         excess_data: Vec::new()
3510                 });
3511
3512                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3513                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3514                         short_channel_id: 6,
3515                         timestamp: 2,
3516                         flags: 0,
3517                         cltv_expiry_delta: 0,
3518                         htlc_minimum_msat: 0,
3519                         htlc_maximum_msat: OptionalField::Present(100_000),
3520                         fee_base_msat: 0,
3521                         fee_proportional_millionths: 0,
3522                         excess_data: Vec::new()
3523                 });
3524                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3525                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3526                         short_channel_id: 11,
3527                         timestamp: 2,
3528                         flags: 0,
3529                         cltv_expiry_delta: 0,
3530                         htlc_minimum_msat: 0,
3531                         htlc_maximum_msat: OptionalField::Present(100_000),
3532                         fee_base_msat: 0,
3533                         fee_proportional_millionths: 0,
3534                         excess_data: Vec::new()
3535                 });
3536
3537                 // Path via {node7, node2} is channels {12, 13, 5}.
3538                 // We already limited them to 200 sats (they are used twice for 100 sats).
3539                 // Nothing to do here.
3540
3541                 {
3542                         // Attempt to route more than available results in a failure.
3543                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[3],
3544                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 350_000, 42, Arc::clone(&logger), &scorer) {
3545                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3546                         } else { panic!(); }
3547                 }
3548
3549                 {
3550                         // Now, attempt to route 300 sats (exact amount we can route).
3551                         // Our algorithm should provide us with these 3 paths, 100 sats each.
3552                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[3],
3553                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 300_000, 42, Arc::clone(&logger), &scorer).unwrap();
3554                         assert_eq!(route.paths.len(), 3);
3555
3556                         let mut total_amount_paid_msat = 0;
3557                         for path in &route.paths {
3558                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3559                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3560                         }
3561                         assert_eq!(total_amount_paid_msat, 300_000);
3562                 }
3563
3564         }
3565
3566         #[test]
3567         fn mpp_cheaper_route_test() {
3568                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3569                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3570                 let scorer = Scorer::new(0);
3571
3572                 // This test checks that if we have two cheaper paths and one more expensive path,
3573                 // so that liquidity-wise any 2 of 3 combination is sufficient,
3574                 // two cheaper paths will be taken.
3575                 // These paths have equal available liquidity.
3576
3577                 // We need a combination of 3 paths:
3578                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
3579                 // Note that these paths overlap (channels 5, 12, 13).
3580                 // Each path will have 100 sats capacity, those channels which
3581                 // are used twice will have 200 sats capacity.
3582
3583                 // Disable other potential paths.
3584                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3585                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3586                         short_channel_id: 2,
3587                         timestamp: 2,
3588                         flags: 2,
3589                         cltv_expiry_delta: 0,
3590                         htlc_minimum_msat: 0,
3591                         htlc_maximum_msat: OptionalField::Present(100_000),
3592                         fee_base_msat: 0,
3593                         fee_proportional_millionths: 0,
3594                         excess_data: Vec::new()
3595                 });
3596                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3597                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3598                         short_channel_id: 7,
3599                         timestamp: 2,
3600                         flags: 2,
3601                         cltv_expiry_delta: 0,
3602                         htlc_minimum_msat: 0,
3603                         htlc_maximum_msat: OptionalField::Present(100_000),
3604                         fee_base_msat: 0,
3605                         fee_proportional_millionths: 0,
3606                         excess_data: Vec::new()
3607                 });
3608
3609                 // Path via {node0, node2} is channels {1, 3, 5}.
3610                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3611                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3612                         short_channel_id: 1,
3613                         timestamp: 2,
3614                         flags: 0,
3615                         cltv_expiry_delta: 0,
3616                         htlc_minimum_msat: 0,
3617                         htlc_maximum_msat: OptionalField::Present(100_000),
3618                         fee_base_msat: 0,
3619                         fee_proportional_millionths: 0,
3620                         excess_data: Vec::new()
3621                 });
3622                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3623                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3624                         short_channel_id: 3,
3625                         timestamp: 2,
3626                         flags: 0,
3627                         cltv_expiry_delta: 0,
3628                         htlc_minimum_msat: 0,
3629                         htlc_maximum_msat: OptionalField::Present(100_000),
3630                         fee_base_msat: 0,
3631                         fee_proportional_millionths: 0,
3632                         excess_data: Vec::new()
3633                 });
3634
3635                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3636                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3637                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3638                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3639                         short_channel_id: 5,
3640                         timestamp: 2,
3641                         flags: 0,
3642                         cltv_expiry_delta: 0,
3643                         htlc_minimum_msat: 0,
3644                         htlc_maximum_msat: OptionalField::Present(200_000),
3645                         fee_base_msat: 0,
3646                         fee_proportional_millionths: 0,
3647                         excess_data: Vec::new()
3648                 });
3649
3650                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3651                 // Add 100 sats to the capacities of {12, 13}, because these channels
3652                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3653                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3654                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3655                         short_channel_id: 12,
3656                         timestamp: 2,
3657                         flags: 0,
3658                         cltv_expiry_delta: 0,
3659                         htlc_minimum_msat: 0,
3660                         htlc_maximum_msat: OptionalField::Present(200_000),
3661                         fee_base_msat: 0,
3662                         fee_proportional_millionths: 0,
3663                         excess_data: Vec::new()
3664                 });
3665                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3666                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3667                         short_channel_id: 13,
3668                         timestamp: 2,
3669                         flags: 0,
3670                         cltv_expiry_delta: 0,
3671                         htlc_minimum_msat: 0,
3672                         htlc_maximum_msat: OptionalField::Present(200_000),
3673                         fee_base_msat: 0,
3674                         fee_proportional_millionths: 0,
3675                         excess_data: Vec::new()
3676                 });
3677
3678                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3679                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3680                         short_channel_id: 6,
3681                         timestamp: 2,
3682                         flags: 0,
3683                         cltv_expiry_delta: 0,
3684                         htlc_minimum_msat: 0,
3685                         htlc_maximum_msat: OptionalField::Present(100_000),
3686                         fee_base_msat: 1_000,
3687                         fee_proportional_millionths: 0,
3688                         excess_data: Vec::new()
3689                 });
3690                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3691                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3692                         short_channel_id: 11,
3693                         timestamp: 2,
3694                         flags: 0,
3695                         cltv_expiry_delta: 0,
3696                         htlc_minimum_msat: 0,
3697                         htlc_maximum_msat: OptionalField::Present(100_000),
3698                         fee_base_msat: 0,
3699                         fee_proportional_millionths: 0,
3700                         excess_data: Vec::new()
3701                 });
3702
3703                 // Path via {node7, node2} is channels {12, 13, 5}.
3704                 // We already limited them to 200 sats (they are used twice for 100 sats).
3705                 // Nothing to do here.
3706
3707                 {
3708                         // Now, attempt to route 180 sats.
3709                         // Our algorithm should provide us with these 2 paths.
3710                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[3],
3711                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 180_000, 42, Arc::clone(&logger), &scorer).unwrap();
3712                         assert_eq!(route.paths.len(), 2);
3713
3714                         let mut total_value_transferred_msat = 0;
3715                         let mut total_paid_msat = 0;
3716                         for path in &route.paths {
3717                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3718                                 total_value_transferred_msat += path.last().unwrap().fee_msat;
3719                                 for hop in path {
3720                                         total_paid_msat += hop.fee_msat;
3721                                 }
3722                         }
3723                         // If we paid fee, this would be higher.
3724                         assert_eq!(total_value_transferred_msat, 180_000);
3725                         let total_fees_paid = total_paid_msat - total_value_transferred_msat;
3726                         assert_eq!(total_fees_paid, 0);
3727                 }
3728         }
3729
3730         #[test]
3731         fn fees_on_mpp_route_test() {
3732                 // This test makes sure that MPP algorithm properly takes into account
3733                 // fees charged on the channels, by making the fees impactful:
3734                 // if the fee is not properly accounted for, the behavior is different.
3735                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3736                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3737                 let scorer = Scorer::new(0);
3738
3739                 // We need a route consisting of 2 paths:
3740                 // From our node to node3 via {node0, node2} and {node7, node2, node4}.
3741                 // We will route 200 sats, Each path will have 100 sats capacity.
3742
3743                 // This test is not particularly stable: e.g.,
3744                 // there's a way to route via {node0, node2, node4}.
3745                 // It works while pathfinding is deterministic, but can be broken otherwise.
3746                 // It's fine to ignore this concern for now.
3747
3748                 // Disable other potential paths.
3749                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3750                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3751                         short_channel_id: 2,
3752                         timestamp: 2,
3753                         flags: 2,
3754                         cltv_expiry_delta: 0,
3755                         htlc_minimum_msat: 0,
3756                         htlc_maximum_msat: OptionalField::Present(100_000),
3757                         fee_base_msat: 0,
3758                         fee_proportional_millionths: 0,
3759                         excess_data: Vec::new()
3760                 });
3761
3762                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3763                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3764                         short_channel_id: 7,
3765                         timestamp: 2,
3766                         flags: 2,
3767                         cltv_expiry_delta: 0,
3768                         htlc_minimum_msat: 0,
3769                         htlc_maximum_msat: OptionalField::Present(100_000),
3770                         fee_base_msat: 0,
3771                         fee_proportional_millionths: 0,
3772                         excess_data: Vec::new()
3773                 });
3774
3775                 // Path via {node0, node2} is channels {1, 3, 5}.
3776                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3777                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3778                         short_channel_id: 1,
3779                         timestamp: 2,
3780                         flags: 0,
3781                         cltv_expiry_delta: 0,
3782                         htlc_minimum_msat: 0,
3783                         htlc_maximum_msat: OptionalField::Present(100_000),
3784                         fee_base_msat: 0,
3785                         fee_proportional_millionths: 0,
3786                         excess_data: Vec::new()
3787                 });
3788                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3789                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3790                         short_channel_id: 3,
3791                         timestamp: 2,
3792                         flags: 0,
3793                         cltv_expiry_delta: 0,
3794                         htlc_minimum_msat: 0,
3795                         htlc_maximum_msat: OptionalField::Present(100_000),
3796                         fee_base_msat: 0,
3797                         fee_proportional_millionths: 0,
3798                         excess_data: Vec::new()
3799                 });
3800
3801                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3802                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3803                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3804                         short_channel_id: 5,
3805                         timestamp: 2,
3806                         flags: 0,
3807                         cltv_expiry_delta: 0,
3808                         htlc_minimum_msat: 0,
3809                         htlc_maximum_msat: OptionalField::Present(100_000),
3810                         fee_base_msat: 0,
3811                         fee_proportional_millionths: 0,
3812                         excess_data: Vec::new()
3813                 });
3814
3815                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3816                 // All channels should be 100 sats capacity. But for the fee experiment,
3817                 // we'll add absolute fee of 150 sats paid for the use channel 6 (paid to node2 on channel 13).
3818                 // Since channel 12 allows to deliver only 250 sats to channel 13, channel 13 can transfer only
3819                 // 100 sats (and pay 150 sats in fees for the use of channel 6),
3820                 // so no matter how large are other channels,
3821                 // the whole path will be limited by 100 sats with just these 2 conditions:
3822                 // - channel 12 capacity is 250 sats
3823                 // - fee for channel 6 is 150 sats
3824                 // Let's test this by enforcing these 2 conditions and removing other limits.
3825                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3826                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3827                         short_channel_id: 12,
3828                         timestamp: 2,
3829                         flags: 0,
3830                         cltv_expiry_delta: 0,
3831                         htlc_minimum_msat: 0,
3832                         htlc_maximum_msat: OptionalField::Present(250_000),
3833                         fee_base_msat: 0,
3834                         fee_proportional_millionths: 0,
3835                         excess_data: Vec::new()
3836                 });
3837                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3838                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3839                         short_channel_id: 13,
3840                         timestamp: 2,
3841                         flags: 0,
3842                         cltv_expiry_delta: 0,
3843                         htlc_minimum_msat: 0,
3844                         htlc_maximum_msat: OptionalField::Absent,
3845                         fee_base_msat: 0,
3846                         fee_proportional_millionths: 0,
3847                         excess_data: Vec::new()
3848                 });
3849
3850                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3851                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3852                         short_channel_id: 6,
3853                         timestamp: 2,
3854                         flags: 0,
3855                         cltv_expiry_delta: 0,
3856                         htlc_minimum_msat: 0,
3857                         htlc_maximum_msat: OptionalField::Absent,
3858                         fee_base_msat: 150_000,
3859                         fee_proportional_millionths: 0,
3860                         excess_data: Vec::new()
3861                 });
3862                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3863                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3864                         short_channel_id: 11,
3865                         timestamp: 2,
3866                         flags: 0,
3867                         cltv_expiry_delta: 0,
3868                         htlc_minimum_msat: 0,
3869                         htlc_maximum_msat: OptionalField::Absent,
3870                         fee_base_msat: 0,
3871                         fee_proportional_millionths: 0,
3872                         excess_data: Vec::new()
3873                 });
3874
3875                 {
3876                         // Attempt to route more than available results in a failure.
3877                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[3],
3878                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 210_000, 42, Arc::clone(&logger), &scorer) {
3879                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3880                         } else { panic!(); }
3881                 }
3882
3883                 {
3884                         // Now, attempt to route 200 sats (exact amount we can route).
3885                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[3],
3886                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 200_000, 42, Arc::clone(&logger), &scorer).unwrap();
3887                         assert_eq!(route.paths.len(), 2);
3888
3889                         let mut total_amount_paid_msat = 0;
3890                         for path in &route.paths {
3891                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3892                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3893                         }
3894                         assert_eq!(total_amount_paid_msat, 200_000);
3895                         assert_eq!(route.get_total_fees(), 150_000);
3896                 }
3897
3898         }
3899
3900         #[test]
3901         fn drop_lowest_channel_mpp_route_test() {
3902                 // This test checks that low-capacity channel is dropped when after
3903                 // path finding we realize that we found more capacity than we need.
3904                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3905                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3906                 let scorer = Scorer::new(0);
3907
3908                 // We need a route consisting of 3 paths:
3909                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
3910
3911                 // The first and the second paths should be sufficient, but the third should be
3912                 // cheaper, so that we select it but drop later.
3913
3914                 // First, we set limits on these (previously unlimited) channels.
3915                 // Their aggregate capacity will be 50 + 60 + 20 = 130 sats.
3916
3917                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50);
3918                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3919                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3920                         short_channel_id: 1,
3921                         timestamp: 2,
3922                         flags: 0,
3923                         cltv_expiry_delta: 0,
3924                         htlc_minimum_msat: 0,
3925                         htlc_maximum_msat: OptionalField::Present(100_000),
3926                         fee_base_msat: 0,
3927                         fee_proportional_millionths: 0,
3928                         excess_data: Vec::new()
3929                 });
3930                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3931                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3932                         short_channel_id: 3,
3933                         timestamp: 2,
3934                         flags: 0,
3935                         cltv_expiry_delta: 0,
3936                         htlc_minimum_msat: 0,
3937                         htlc_maximum_msat: OptionalField::Present(50_000),
3938                         fee_base_msat: 100,
3939                         fee_proportional_millionths: 0,
3940                         excess_data: Vec::new()
3941                 });
3942
3943                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats (total limit 60);
3944                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3945                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3946                         short_channel_id: 12,
3947                         timestamp: 2,
3948                         flags: 0,
3949                         cltv_expiry_delta: 0,
3950                         htlc_minimum_msat: 0,
3951                         htlc_maximum_msat: OptionalField::Present(60_000),
3952                         fee_base_msat: 100,
3953                         fee_proportional_millionths: 0,
3954                         excess_data: Vec::new()
3955                 });
3956                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3957                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3958                         short_channel_id: 13,
3959                         timestamp: 2,
3960                         flags: 0,
3961                         cltv_expiry_delta: 0,
3962                         htlc_minimum_msat: 0,
3963                         htlc_maximum_msat: OptionalField::Present(60_000),
3964                         fee_base_msat: 0,
3965                         fee_proportional_millionths: 0,
3966                         excess_data: Vec::new()
3967                 });
3968
3969                 // Path via node1 is channels {2, 4}. Limit them to 20 and 20 sats (total capacity 20 sats).
3970                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3971                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3972                         short_channel_id: 2,
3973                         timestamp: 2,
3974                         flags: 0,
3975                         cltv_expiry_delta: 0,
3976                         htlc_minimum_msat: 0,
3977                         htlc_maximum_msat: OptionalField::Present(20_000),
3978                         fee_base_msat: 0,
3979                         fee_proportional_millionths: 0,
3980                         excess_data: Vec::new()
3981                 });
3982                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3983                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3984                         short_channel_id: 4,
3985                         timestamp: 2,
3986                         flags: 0,
3987                         cltv_expiry_delta: 0,
3988                         htlc_minimum_msat: 0,
3989                         htlc_maximum_msat: OptionalField::Present(20_000),
3990                         fee_base_msat: 0,
3991                         fee_proportional_millionths: 0,
3992                         excess_data: Vec::new()
3993                 });
3994
3995                 {
3996                         // Attempt to route more than available results in a failure.
3997                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
3998                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 150_000, 42, Arc::clone(&logger), &scorer) {
3999                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
4000                         } else { panic!(); }
4001                 }
4002
4003                 {
4004                         // Now, attempt to route 125 sats (just a bit below the capacity of 3 channels).
4005                         // Our algorithm should provide us with these 3 paths.
4006                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
4007                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 125_000, 42, Arc::clone(&logger), &scorer).unwrap();
4008                         assert_eq!(route.paths.len(), 3);
4009                         let mut total_amount_paid_msat = 0;
4010                         for path in &route.paths {
4011                                 assert_eq!(path.len(), 2);
4012                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
4013                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
4014                         }
4015                         assert_eq!(total_amount_paid_msat, 125_000);
4016                 }
4017
4018                 {
4019                         // Attempt to route without the last small cheap channel
4020                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2],
4021                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 90_000, 42, Arc::clone(&logger), &scorer).unwrap();
4022                         assert_eq!(route.paths.len(), 2);
4023                         let mut total_amount_paid_msat = 0;
4024                         for path in &route.paths {
4025                                 assert_eq!(path.len(), 2);
4026                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
4027                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
4028                         }
4029                         assert_eq!(total_amount_paid_msat, 90_000);
4030                 }
4031         }
4032
4033         #[test]
4034         fn min_criteria_consistency() {
4035                 // Test that we don't use an inconsistent metric between updating and walking nodes during
4036                 // our Dijkstra's pass. In the initial version of MPP, the "best source" for a given node
4037                 // was updated with a different criterion from the heap sorting, resulting in loops in
4038                 // calculated paths. We test for that specific case here.
4039
4040                 // We construct a network that looks like this:
4041                 //
4042                 //            node2 -1(3)2- node3
4043                 //              2          2
4044                 //               (2)     (4)
4045                 //                  1   1
4046                 //    node1 -1(5)2- node4 -1(1)2- node6
4047                 //    2
4048                 //   (6)
4049                 //        1
4050                 // our_node
4051                 //
4052                 // We create a loop on the side of our real path - our destination is node 6, with a
4053                 // previous hop of node 4. From 4, the cheapest previous path is channel 2 from node 2,
4054                 // followed by node 3 over channel 3. Thereafter, the cheapest next-hop is back to node 4
4055                 // (this time over channel 4). Channel 4 has 0 htlc_minimum_msat whereas channel 1 (the
4056                 // other channel with a previous-hop of node 4) has a high (but irrelevant to the overall
4057                 // payment) htlc_minimum_msat. In the original algorithm, this resulted in node4's
4058                 // "previous hop" being set to node 3, creating a loop in the path.
4059                 let secp_ctx = Secp256k1::new();
4060                 let logger = Arc::new(test_utils::TestLogger::new());
4061                 let network_graph = NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash());
4062                 let net_graph_msg_handler = NetGraphMsgHandler::new(network_graph, None, Arc::clone(&logger));
4063                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
4064                 let scorer = Scorer::new(0);
4065
4066                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
4067                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4068                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4069                         short_channel_id: 6,
4070                         timestamp: 1,
4071                         flags: 0,
4072                         cltv_expiry_delta: (6 << 8) | 0,
4073                         htlc_minimum_msat: 0,
4074                         htlc_maximum_msat: OptionalField::Absent,
4075                         fee_base_msat: 0,
4076                         fee_proportional_millionths: 0,
4077                         excess_data: Vec::new()
4078                 });
4079                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
4080
4081                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
4082                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
4083                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4084                         short_channel_id: 5,
4085                         timestamp: 1,
4086                         flags: 0,
4087                         cltv_expiry_delta: (5 << 8) | 0,
4088                         htlc_minimum_msat: 0,
4089                         htlc_maximum_msat: OptionalField::Absent,
4090                         fee_base_msat: 100,
4091                         fee_proportional_millionths: 0,
4092                         excess_data: Vec::new()
4093                 });
4094                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
4095
4096                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
4097                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
4098                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4099                         short_channel_id: 4,
4100                         timestamp: 1,
4101                         flags: 0,
4102                         cltv_expiry_delta: (4 << 8) | 0,
4103                         htlc_minimum_msat: 0,
4104                         htlc_maximum_msat: OptionalField::Absent,
4105                         fee_base_msat: 0,
4106                         fee_proportional_millionths: 0,
4107                         excess_data: Vec::new()
4108                 });
4109                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
4110
4111                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
4112                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
4113                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4114                         short_channel_id: 3,
4115                         timestamp: 1,
4116                         flags: 0,
4117                         cltv_expiry_delta: (3 << 8) | 0,
4118                         htlc_minimum_msat: 0,
4119                         htlc_maximum_msat: OptionalField::Absent,
4120                         fee_base_msat: 0,
4121                         fee_proportional_millionths: 0,
4122                         excess_data: Vec::new()
4123                 });
4124                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
4125
4126                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
4127                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
4128                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4129                         short_channel_id: 2,
4130                         timestamp: 1,
4131                         flags: 0,
4132                         cltv_expiry_delta: (2 << 8) | 0,
4133                         htlc_minimum_msat: 0,
4134                         htlc_maximum_msat: OptionalField::Absent,
4135                         fee_base_msat: 0,
4136                         fee_proportional_millionths: 0,
4137                         excess_data: Vec::new()
4138                 });
4139
4140                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[6], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
4141                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
4142                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4143                         short_channel_id: 1,
4144                         timestamp: 1,
4145                         flags: 0,
4146                         cltv_expiry_delta: (1 << 8) | 0,
4147                         htlc_minimum_msat: 100,
4148                         htlc_maximum_msat: OptionalField::Absent,
4149                         fee_base_msat: 0,
4150                         fee_proportional_millionths: 0,
4151                         excess_data: Vec::new()
4152                 });
4153                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[6], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
4154
4155                 {
4156                         // Now ensure the route flows simply over nodes 1 and 4 to 6.
4157                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, None, &Vec::new(), 10_000, 42, Arc::clone(&logger), &scorer).unwrap();
4158                         assert_eq!(route.paths.len(), 1);
4159                         assert_eq!(route.paths[0].len(), 3);
4160
4161                         assert_eq!(route.paths[0][0].pubkey, nodes[1]);
4162                         assert_eq!(route.paths[0][0].short_channel_id, 6);
4163                         assert_eq!(route.paths[0][0].fee_msat, 100);
4164                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (5 << 8) | 0);
4165                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(1));
4166                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(6));
4167
4168                         assert_eq!(route.paths[0][1].pubkey, nodes[4]);
4169                         assert_eq!(route.paths[0][1].short_channel_id, 5);
4170                         assert_eq!(route.paths[0][1].fee_msat, 0);
4171                         assert_eq!(route.paths[0][1].cltv_expiry_delta, (1 << 8) | 0);
4172                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(4));
4173                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(5));
4174
4175                         assert_eq!(route.paths[0][2].pubkey, nodes[6]);
4176                         assert_eq!(route.paths[0][2].short_channel_id, 1);
4177                         assert_eq!(route.paths[0][2].fee_msat, 10_000);
4178                         assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
4179                         assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
4180                         assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(1));
4181                 }
4182         }
4183
4184
4185         #[test]
4186         fn exact_fee_liquidity_limit() {
4187                 // Test that if, while walking the graph, we find a hop that has exactly enough liquidity
4188                 // for us, including later hop fees, we take it. In the first version of our MPP algorithm
4189                 // we calculated fees on a higher value, resulting in us ignoring such paths.
4190                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
4191                 let (our_privkey, our_id, _, nodes) = get_nodes(&secp_ctx);
4192                 let scorer = Scorer::new(0);
4193
4194                 // We modify the graph to set the htlc_maximum of channel 2 to below the value we wish to
4195                 // send.
4196                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4197                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4198                         short_channel_id: 2,
4199                         timestamp: 2,
4200                         flags: 0,
4201                         cltv_expiry_delta: 0,
4202                         htlc_minimum_msat: 0,
4203                         htlc_maximum_msat: OptionalField::Present(85_000),
4204                         fee_base_msat: 0,
4205                         fee_proportional_millionths: 0,
4206                         excess_data: Vec::new()
4207                 });
4208
4209                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4210                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4211                         short_channel_id: 12,
4212                         timestamp: 2,
4213                         flags: 0,
4214                         cltv_expiry_delta: (4 << 8) | 1,
4215                         htlc_minimum_msat: 0,
4216                         htlc_maximum_msat: OptionalField::Present(270_000),
4217                         fee_base_msat: 0,
4218                         fee_proportional_millionths: 1000000,
4219                         excess_data: Vec::new()
4220                 });
4221
4222                 {
4223                         // Now, attempt to route 90 sats, which is exactly 90 sats at the last hop, plus the
4224                         // 200% fee charged channel 13 in the 1-to-2 direction.
4225                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], None, None, &Vec::new(), 90_000, 42, Arc::clone(&logger), &scorer).unwrap();
4226                         assert_eq!(route.paths.len(), 1);
4227                         assert_eq!(route.paths[0].len(), 2);
4228
4229                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
4230                         assert_eq!(route.paths[0][0].short_channel_id, 12);
4231                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
4232                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
4233                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
4234                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
4235
4236                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
4237                         assert_eq!(route.paths[0][1].short_channel_id, 13);
4238                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
4239                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
4240                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
4241                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
4242                 }
4243         }
4244
4245         #[test]
4246         fn htlc_max_reduction_below_min() {
4247                 // Test that if, while walking the graph, we reduce the value being sent to meet an
4248                 // htlc_maximum_msat, we don't end up undershooting a later htlc_minimum_msat. In the
4249                 // initial version of MPP we'd accept such routes but reject them while recalculating fees,
4250                 // resulting in us thinking there is no possible path, even if other paths exist.
4251                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
4252                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
4253                 let scorer = Scorer::new(0);
4254
4255                 // We modify the graph to set the htlc_minimum of channel 2 and 4 as needed - channel 2
4256                 // gets an htlc_maximum_msat of 80_000 and channel 4 an htlc_minimum_msat of 90_000. We
4257                 // then try to send 90_000.
4258                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
4259                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4260                         short_channel_id: 2,
4261                         timestamp: 2,
4262                         flags: 0,
4263                         cltv_expiry_delta: 0,
4264                         htlc_minimum_msat: 0,
4265                         htlc_maximum_msat: OptionalField::Present(80_000),
4266                         fee_base_msat: 0,
4267                         fee_proportional_millionths: 0,
4268                         excess_data: Vec::new()
4269                 });
4270                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
4271                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
4272                         short_channel_id: 4,
4273                         timestamp: 2,
4274                         flags: 0,
4275                         cltv_expiry_delta: (4 << 8) | 1,
4276                         htlc_minimum_msat: 90_000,
4277                         htlc_maximum_msat: OptionalField::Absent,
4278                         fee_base_msat: 0,
4279                         fee_proportional_millionths: 0,
4280                         excess_data: Vec::new()
4281                 });
4282
4283                 {
4284                         // Now, attempt to route 90 sats, hitting the htlc_minimum on channel 4, but
4285                         // overshooting the htlc_maximum on channel 2. Thus, we should pick the (absurdly
4286                         // expensive) channels 12-13 path.
4287                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph, &nodes[2], Some(InvoiceFeatures::known()), None, &Vec::new(), 90_000, 42, Arc::clone(&logger), &scorer).unwrap();
4288                         assert_eq!(route.paths.len(), 1);
4289                         assert_eq!(route.paths[0].len(), 2);
4290
4291                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
4292                         assert_eq!(route.paths[0][0].short_channel_id, 12);
4293                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
4294                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
4295                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
4296                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
4297
4298                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
4299                         assert_eq!(route.paths[0][1].short_channel_id, 13);
4300                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
4301                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
4302                         assert_eq!(route.paths[0][1].node_features.le_flags(), InvoiceFeatures::known().le_flags());
4303                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
4304                 }
4305         }
4306
4307         #[test]
4308         fn multiple_direct_first_hops() {
4309                 // Previously we'd only ever considered one first hop path per counterparty.
4310                 // However, as we don't restrict users to one channel per peer, we really need to support
4311                 // looking at all first hop paths.
4312                 // Here we test that we do not ignore all-but-the-last first hop paths per counterparty (as
4313                 // we used to do by overwriting the `first_hop_targets` hashmap entry) and that we can MPP
4314                 // route over multiple channels with the same first hop.
4315                 let secp_ctx = Secp256k1::new();
4316                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
4317                 let logger = Arc::new(test_utils::TestLogger::new());
4318                 let network_graph = NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash());
4319                 let scorer = Scorer::new(0);
4320
4321                 {
4322                         let route = get_route(&our_id, &network_graph, &nodes[0], Some(InvoiceFeatures::known()), Some(&[
4323                                 &get_channel_details(Some(3), nodes[0], InitFeatures::known(), 200_000),
4324                                 &get_channel_details(Some(2), nodes[0], InitFeatures::known(), 10_000),
4325                         ]), &[], 100_000, 42, Arc::clone(&logger), &scorer).unwrap();
4326                         assert_eq!(route.paths.len(), 1);
4327                         assert_eq!(route.paths[0].len(), 1);
4328
4329                         assert_eq!(route.paths[0][0].pubkey, nodes[0]);
4330                         assert_eq!(route.paths[0][0].short_channel_id, 3);
4331                         assert_eq!(route.paths[0][0].fee_msat, 100_000);
4332                 }
4333                 {
4334                         let route = get_route(&our_id, &network_graph, &nodes[0], Some(InvoiceFeatures::known()), Some(&[
4335                                 &get_channel_details(Some(3), nodes[0], InitFeatures::known(), 50_000),
4336                                 &get_channel_details(Some(2), nodes[0], InitFeatures::known(), 50_000),
4337                         ]), &[], 100_000, 42, Arc::clone(&logger), &scorer).unwrap();
4338                         assert_eq!(route.paths.len(), 2);
4339                         assert_eq!(route.paths[0].len(), 1);
4340                         assert_eq!(route.paths[1].len(), 1);
4341
4342                         assert_eq!(route.paths[0][0].pubkey, nodes[0]);
4343                         assert_eq!(route.paths[0][0].short_channel_id, 3);
4344                         assert_eq!(route.paths[0][0].fee_msat, 50_000);
4345
4346                         assert_eq!(route.paths[1][0].pubkey, nodes[0]);
4347                         assert_eq!(route.paths[1][0].short_channel_id, 2);
4348                         assert_eq!(route.paths[1][0].fee_msat, 50_000);
4349                 }
4350         }
4351
4352         #[test]
4353         fn prefers_shorter_route_with_higher_fees() {
4354                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
4355                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
4356
4357                 // Without penalizing each hop 100 msats, a longer path with lower fees is chosen.
4358                 let scorer = Scorer::new(0);
4359                 let route = get_route(
4360                         &our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, None,
4361                         &last_hops(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger), &scorer
4362                 ).unwrap();
4363                 let path = route.paths[0].iter().map(|hop| hop.short_channel_id).collect::<Vec<_>>();
4364
4365                 assert_eq!(route.get_total_fees(), 100);
4366                 assert_eq!(route.get_total_amount(), 100);
4367                 assert_eq!(path, vec![2, 4, 6, 11, 8]);
4368
4369                 // Applying a 100 msat penalty to each hop results in taking channels 7 and 10 to nodes[6]
4370                 // from nodes[2] rather than channel 6, 11, and 8, even though the longer path is cheaper.
4371                 let scorer = Scorer::new(100);
4372                 let route = get_route(
4373                         &our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, None,
4374                         &last_hops(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger), &scorer
4375                 ).unwrap();
4376                 let path = route.paths[0].iter().map(|hop| hop.short_channel_id).collect::<Vec<_>>();
4377
4378                 assert_eq!(route.get_total_fees(), 300);
4379                 assert_eq!(route.get_total_amount(), 100);
4380                 assert_eq!(path, vec![2, 4, 7, 10]);
4381         }
4382
4383         struct BadChannelScorer {
4384                 short_channel_id: u64,
4385         }
4386
4387         impl routing::Score for BadChannelScorer {
4388                 fn channel_penalty_msat(&self, short_channel_id: u64, _source: &NodeId, _target: &NodeId) -> u64 {
4389                         if short_channel_id == self.short_channel_id { u64::max_value() } else { 0 }
4390                 }
4391         }
4392
4393         struct BadNodeScorer {
4394                 node_id: NodeId,
4395         }
4396
4397         impl routing::Score for BadNodeScorer {
4398                 fn channel_penalty_msat(&self, _short_channel_id: u64, _source: &NodeId, target: &NodeId) -> u64 {
4399                         if *target == self.node_id { u64::max_value() } else { 0 }
4400                 }
4401         }
4402
4403         #[test]
4404         fn avoids_routing_through_bad_channels_and_nodes() {
4405                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
4406                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
4407
4408                 // A path to nodes[6] exists when no penalties are applied to any channel.
4409                 let scorer = Scorer::new(0);
4410                 let route = get_route(
4411                         &our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, None,
4412                         &last_hops(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger), &scorer
4413                 ).unwrap();
4414                 let path = route.paths[0].iter().map(|hop| hop.short_channel_id).collect::<Vec<_>>();
4415
4416                 assert_eq!(route.get_total_fees(), 100);
4417                 assert_eq!(route.get_total_amount(), 100);
4418                 assert_eq!(path, vec![2, 4, 6, 11, 8]);
4419
4420                 // A different path to nodes[6] exists if channel 6 cannot be routed over.
4421                 let scorer = BadChannelScorer { short_channel_id: 6 };
4422                 let route = get_route(
4423                         &our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, None,
4424                         &last_hops(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger), &scorer
4425                 ).unwrap();
4426                 let path = route.paths[0].iter().map(|hop| hop.short_channel_id).collect::<Vec<_>>();
4427
4428                 assert_eq!(route.get_total_fees(), 300);
4429                 assert_eq!(route.get_total_amount(), 100);
4430                 assert_eq!(path, vec![2, 4, 7, 10]);
4431
4432                 // A path to nodes[6] does not exist if nodes[2] cannot be routed through.
4433                 let scorer = BadNodeScorer { node_id: NodeId::from_pubkey(&nodes[2]) };
4434                 match get_route(
4435                         &our_id, &net_graph_msg_handler.network_graph, &nodes[6], None, None,
4436                         &last_hops(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger), &scorer
4437                 ) {
4438                         Err(LightningError { err, .. } ) => {
4439                                 assert_eq!(err, "Failed to find a path to the given destination");
4440                         },
4441                         Ok(_) => panic!("Expected error"),
4442                 }
4443         }
4444
4445         #[test]
4446         fn total_fees_single_path() {
4447                 let route = Route {
4448                         paths: vec![vec![
4449                                 RouteHop {
4450                                         pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
4451                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4452                                         short_channel_id: 0, fee_msat: 100, cltv_expiry_delta: 0
4453                                 },
4454                                 RouteHop {
4455                                         pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
4456                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4457                                         short_channel_id: 0, fee_msat: 150, cltv_expiry_delta: 0
4458                                 },
4459                                 RouteHop {
4460                                         pubkey: PublicKey::from_slice(&hex::decode("027f31ebc5462c1fdce1b737ecff52d37d75dea43ce11c74d25aa297165faa2007").unwrap()[..]).unwrap(),
4461                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4462                                         short_channel_id: 0, fee_msat: 225, cltv_expiry_delta: 0
4463                                 },
4464                         ]],
4465                 };
4466
4467                 assert_eq!(route.get_total_fees(), 250);
4468                 assert_eq!(route.get_total_amount(), 225);
4469         }
4470
4471         #[test]
4472         fn total_fees_multi_path() {
4473                 let route = Route {
4474                         paths: vec![vec![
4475                                 RouteHop {
4476                                         pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
4477                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4478                                         short_channel_id: 0, fee_msat: 100, cltv_expiry_delta: 0
4479                                 },
4480                                 RouteHop {
4481                                         pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
4482                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4483                                         short_channel_id: 0, fee_msat: 150, cltv_expiry_delta: 0
4484                                 },
4485                         ],vec![
4486                                 RouteHop {
4487                                         pubkey: PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap(),
4488                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4489                                         short_channel_id: 0, fee_msat: 100, cltv_expiry_delta: 0
4490                                 },
4491                                 RouteHop {
4492                                         pubkey: PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap(),
4493                                         channel_features: ChannelFeatures::empty(), node_features: NodeFeatures::empty(),
4494                                         short_channel_id: 0, fee_msat: 150, cltv_expiry_delta: 0
4495                                 },
4496                         ]],
4497                 };
4498
4499                 assert_eq!(route.get_total_fees(), 200);
4500                 assert_eq!(route.get_total_amount(), 300);
4501         }
4502
4503         #[test]
4504         fn total_empty_route_no_panic() {
4505                 // In an earlier version of `Route::get_total_fees` and `Route::get_total_amount`, they
4506                 // would both panic if the route was completely empty. We test to ensure they return 0
4507                 // here, even though its somewhat nonsensical as a route.
4508                 let route = Route { paths: Vec::new() };
4509
4510                 assert_eq!(route.get_total_fees(), 0);
4511                 assert_eq!(route.get_total_amount(), 0);
4512         }
4513
4514         #[cfg(not(feature = "no-std"))]
4515         pub(super) fn random_init_seed() -> u64 {
4516                 // Because the default HashMap in std pulls OS randomness, we can use it as a (bad) RNG.
4517                 use core::hash::{BuildHasher, Hasher};
4518                 let seed = std::collections::hash_map::RandomState::new().build_hasher().finish();
4519                 println!("Using seed of {}", seed);
4520                 seed
4521         }
4522         #[cfg(not(feature = "no-std"))]
4523         use util::ser::Readable;
4524
4525         #[test]
4526         #[cfg(not(feature = "no-std"))]
4527         fn generate_routes() {
4528                 let mut d = match super::test_utils::get_route_file() {
4529                         Ok(f) => f,
4530                         Err(e) => {
4531                                 eprintln!("{}", e);
4532                                 return;
4533                         },
4534                 };
4535                 let graph = NetworkGraph::read(&mut d).unwrap();
4536                 let scorer = Scorer::new(0);
4537
4538                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
4539                 let mut seed = random_init_seed() as usize;
4540                 let nodes = graph.read_only().nodes().clone();
4541                 'load_endpoints: for _ in 0..10 {
4542                         loop {
4543                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4544                                 let src = &PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4545                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4546                                 let dst = &PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4547                                 let amt = seed as u64 % 200_000_000;
4548                                 if get_route(src, &graph, dst, None, None, &[], amt, 42, &test_utils::TestLogger::new(), &scorer).is_ok() {
4549                                         continue 'load_endpoints;
4550                                 }
4551                         }
4552                 }
4553         }
4554
4555         #[test]
4556         #[cfg(not(feature = "no-std"))]
4557         fn generate_routes_mpp() {
4558                 let mut d = match super::test_utils::get_route_file() {
4559                         Ok(f) => f,
4560                         Err(e) => {
4561                                 eprintln!("{}", e);
4562                                 return;
4563                         },
4564                 };
4565                 let graph = NetworkGraph::read(&mut d).unwrap();
4566                 let scorer = Scorer::new(0);
4567
4568                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
4569                 let mut seed = random_init_seed() as usize;
4570                 let nodes = graph.read_only().nodes().clone();
4571                 'load_endpoints: for _ in 0..10 {
4572                         loop {
4573                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4574                                 let src = &PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4575                                 seed = seed.overflowing_mul(0xdeadbeef).0;
4576                                 let dst = &PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4577                                 let amt = seed as u64 % 200_000_000;
4578                                 if get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &test_utils::TestLogger::new(), &scorer).is_ok() {
4579                                         continue 'load_endpoints;
4580                                 }
4581                         }
4582                 }
4583         }
4584 }
4585
4586 #[cfg(all(test, not(feature = "no-std")))]
4587 pub(crate) mod test_utils {
4588         use std::fs::File;
4589         /// Tries to open a network graph file, or panics with a URL to fetch it.
4590         pub(crate) fn get_route_file() -> Result<std::fs::File, &'static str> {
4591                 let res = File::open("net_graph-2021-05-31.bin") // By default we're run in RL/lightning
4592                         .or_else(|_| File::open("lightning/net_graph-2021-05-31.bin")) // We may be run manually in RL/
4593                         .or_else(|_| { // Fall back to guessing based on the binary location
4594                                 // path is likely something like .../rust-lightning/target/debug/deps/lightning-...
4595                                 let mut path = std::env::current_exe().unwrap();
4596                                 path.pop(); // lightning-...
4597                                 path.pop(); // deps
4598                                 path.pop(); // debug
4599                                 path.pop(); // target
4600                                 path.push("lightning");
4601                                 path.push("net_graph-2021-05-31.bin");
4602                                 eprintln!("{}", path.to_str().unwrap());
4603                                 File::open(path)
4604                         })
4605                 .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");
4606                 #[cfg(require_route_graph_test)]
4607                 return Ok(res.unwrap());
4608                 #[cfg(not(require_route_graph_test))]
4609                 return res;
4610         }
4611 }
4612
4613 #[cfg(all(test, feature = "unstable", not(feature = "no-std")))]
4614 mod benches {
4615         use super::*;
4616         use routing::scorer::Scorer;
4617         use util::logger::{Logger, Record};
4618
4619         use test::Bencher;
4620
4621         struct DummyLogger {}
4622         impl Logger for DummyLogger {
4623                 fn log(&self, _record: &Record) {}
4624         }
4625
4626         #[bench]
4627         fn generate_routes(bench: &mut Bencher) {
4628                 let mut d = test_utils::get_route_file().unwrap();
4629                 let graph = NetworkGraph::read(&mut d).unwrap();
4630                 let nodes = graph.read_only().nodes().clone();
4631                 let scorer = Scorer::new(0);
4632
4633                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
4634                 let mut path_endpoints = Vec::new();
4635                 let mut seed: usize = 0xdeadbeef;
4636                 'load_endpoints: for _ in 0..100 {
4637                         loop {
4638                                 seed *= 0xdeadbeef;
4639                                 let src = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4640                                 seed *= 0xdeadbeef;
4641                                 let dst = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4642                                 let amt = seed as u64 % 1_000_000;
4643                                 if get_route(&src, &graph, &dst, None, None, &[], amt, 42, &DummyLogger{}, &scorer).is_ok() {
4644                                         path_endpoints.push((src, dst, amt));
4645                                         continue 'load_endpoints;
4646                                 }
4647                         }
4648                 }
4649
4650                 // ...then benchmark finding paths between the nodes we learned.
4651                 let mut idx = 0;
4652                 bench.iter(|| {
4653                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
4654                         assert!(get_route(&src, &graph, &dst, None, None, &[], amt, 42, &DummyLogger{}, &scorer).is_ok());
4655                         idx += 1;
4656                 });
4657         }
4658
4659         #[bench]
4660         fn generate_mpp_routes(bench: &mut Bencher) {
4661                 let mut d = test_utils::get_route_file().unwrap();
4662                 let graph = NetworkGraph::read(&mut d).unwrap();
4663                 let nodes = graph.read_only().nodes().clone();
4664                 let scorer = Scorer::new(0);
4665
4666                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
4667                 let mut path_endpoints = Vec::new();
4668                 let mut seed: usize = 0xdeadbeef;
4669                 'load_endpoints: for _ in 0..100 {
4670                         loop {
4671                                 seed *= 0xdeadbeef;
4672                                 let src = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4673                                 seed *= 0xdeadbeef;
4674                                 let dst = PublicKey::from_slice(nodes.keys().skip(seed % nodes.len()).next().unwrap().as_slice()).unwrap();
4675                                 let amt = seed as u64 % 1_000_000;
4676                                 if get_route(&src, &graph, &dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &DummyLogger{}, &scorer).is_ok() {
4677                                         path_endpoints.push((src, dst, amt));
4678                                         continue 'load_endpoints;
4679                                 }
4680                         }
4681                 }
4682
4683                 // ...then benchmark finding paths between the nodes we learned.
4684                 let mut idx = 0;
4685                 bench.iter(|| {
4686                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
4687                         assert!(get_route(&src, &graph, &dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &DummyLogger{}, &scorer).is_ok());
4688                         idx += 1;
4689                 });
4690         }
4691 }