_ 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::network_graph::{NetworkGraph, RoutingFees};
  21 use util::ser::{Writeable, Readable};
  22 use util::logger::Logger;
  23
  24 use std::cmp;
  25 use std::collections::{HashMap, BinaryHeap};
  26 use std::ops::Deref;
  27
  28 /// A hop in a route
  29 #[derive(Clone, PartialEq)]
  30 pub struct RouteHop {
  31         /// The node_id of the node at this hop.
  32         pub pubkey: PublicKey,
  33         /// The node_announcement features of the node at this hop. For the last hop, these may be
  34         /// amended to match the features present in the invoice this node generated.
  35         pub node_features: NodeFeatures,
  36         /// The channel that should be used from the previous hop to reach this node.
  37         pub short_channel_id: u64,
  38         /// The channel_announcement features of the channel that should be used from the previous hop
  39         /// to reach this node.
  40         pub channel_features: ChannelFeatures,
  41         /// The fee taken on this hop (for paying for the use of the *next* channel in the path).
  42         /// For the last hop, this should be the full value of the payment (might be more than
  43         /// requested if we had to match htlc_minimum_msat).
  44         pub fee_msat: u64,
  45         /// The CLTV delta added for this hop. For the last hop, this should be the full CLTV value
  46         /// expected at the destination, in excess of the current block height.
  47         pub cltv_expiry_delta: u32,
  48 }
  49
  50 /// (C-not exported)
  51 impl Writeable for Vec<RouteHop> {
  52         fn write<W: ::util::ser::Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
  53                 (self.len() as u8).write(writer)?;
  54                 for hop in self.iter() {
  55                         hop.pubkey.write(writer)?;
  56                         hop.node_features.write(writer)?;
  57                         hop.short_channel_id.write(writer)?;
  58                         hop.channel_features.write(writer)?;
  59                         hop.fee_msat.write(writer)?;
  60                         hop.cltv_expiry_delta.write(writer)?;
  61                 }
  62                 Ok(())
  63         }
  64 }
  65
  66 /// (C-not exported)
  67 impl Readable for Vec<RouteHop> {
  68         fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Vec<RouteHop>, DecodeError> {
  69                 let hops_count: u8 = Readable::read(reader)?;
  70                 let mut hops = Vec::with_capacity(hops_count as usize);
  71                 for _ in 0..hops_count {
  72                         hops.push(RouteHop {
  73                                 pubkey: Readable::read(reader)?,
  74                                 node_features: Readable::read(reader)?,
  75                                 short_channel_id: Readable::read(reader)?,
  76                                 channel_features: Readable::read(reader)?,
  77                                 fee_msat: Readable::read(reader)?,
  78                                 cltv_expiry_delta: Readable::read(reader)?,
  79                         });
  80                 }
  81                 Ok(hops)
  82         }
  83 }
  84
  85 /// A route directs a payment from the sender (us) to the recipient. If the recipient supports MPP,
  86 /// it can take multiple paths. Each path is composed of one or more hops through the network.
  87 #[derive(Clone, PartialEq)]
  88 pub struct Route {
  89         /// The list of routes taken for a single (potentially-)multi-part payment. The pubkey of the
  90         /// last RouteHop in each path must be the same.
  91         /// Each entry represents a list of hops, NOT INCLUDING our own, where the last hop is the
  92         /// destination. Thus, this must always be at least length one. While the maximum length of any
  93         /// given path is variable, keeping the length of any path to less than 20 should currently
  94         /// ensure it is viable.
  95         pub paths: Vec<Vec<RouteHop>>,
  96 }
  97
  98 impl Writeable for Route {
  99         fn write<W: ::util::ser::Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
 100                 (self.paths.len() as u64).write(writer)?;
 101                 for hops in self.paths.iter() {
 102                         hops.write(writer)?;
 103                 }
 104                 Ok(())
 105         }
 106 }
 107
 108 impl Readable for Route {
 109         fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Route, DecodeError> {
 110                 let path_count: u64 = Readable::read(reader)?;
 111                 let mut paths = Vec::with_capacity(cmp::min(path_count, 128) as usize);
 112                 for _ in 0..path_count {
 113                         paths.push(Readable::read(reader)?);
 114                 }
 115                 Ok(Route { paths })
 116         }
 117 }
 118
 119 /// A channel descriptor which provides a last-hop route to get_route
 120 #[derive(Clone)]
 121 pub struct RouteHint {
 122         /// The node_id of the non-target end of the route
 123         pub src_node_id: PublicKey,
 124         /// The short_channel_id of this channel
 125         pub short_channel_id: u64,
 126         /// The fees which must be paid to use this channel
 127         pub fees: RoutingFees,
 128         /// The difference in CLTV values between this node and the next node.
 129         pub cltv_expiry_delta: u16,
 130         /// The minimum value, in msat, which must be relayed to the next hop.
 131         pub htlc_minimum_msat: Option<u64>,
 132         /// The maximum value in msat available for routing with a single HTLC.
 133         pub htlc_maximum_msat: Option<u64>,
 134 }
 135
 136 #[derive(Eq, PartialEq)]
 137 struct RouteGraphNode {
 138         pubkey: PublicKey,
 139         lowest_fee_to_peer_through_node: u64,
 140         lowest_fee_to_node: u64,
 141         // The maximum value a yet-to-be-constructed payment path might flow through this node.
 142         // This value is upper-bounded by us by:
 143         // - how much is needed for a path being constructed
 144         // - how much value can channels following this node (up to the destination) can contribute,
 145         //   considering their capacity and fees
 146         value_contribution_msat: u64,
 147         /// The maximum htlc_minimum_msat along the path, taking into consideration the fees required
 148         /// to meet the minimum over the hops required to get there.
 149         path_htlc_minimum_msat: u64,
 150 }
 151
 152 impl cmp::Ord for RouteGraphNode {
 153         fn cmp(&self, other: &RouteGraphNode) -> cmp::Ordering {
 154                 cmp::max(other.lowest_fee_to_peer_through_node, other.path_htlc_minimum_msat)
 155                         .cmp(&cmp::max(self.lowest_fee_to_peer_through_node, self.path_htlc_minimum_msat))
 156                         .then_with(|| other.pubkey.serialize().cmp(&self.pubkey.serialize()))
 157         }
 158 }
 159
 160 impl cmp::PartialOrd for RouteGraphNode {
 161         fn partial_cmp(&self, other: &RouteGraphNode) -> Option<cmp::Ordering> {
 162                 Some(self.cmp(other))
 163         }
 164 }
 165
 166 struct DummyDirectionalChannelInfo {
 167         cltv_expiry_delta: u32,
 168         htlc_minimum_msat: u64,
 169         htlc_maximum_msat: Option<u64>,
 170         fees: RoutingFees,
 171 }
 172
 173 /// It's useful to keep track of the hops associated with the fees required to use them,
 174 /// so that we can choose cheaper paths (as per Dijkstra's algorithm).
 175 /// Fee values should be updated only in the context of the whole path, see update_value_and_recompute_fees.
 176 /// These fee values are useful to choose hops as we traverse the graph "payee-to-payer".
 177 #[derive(Clone)]
 178 struct PathBuildingHop {
 179         /// Hop-specific details unrelated to the path during the routing phase,
 180         /// but rather relevant to the LN graph.
 181         route_hop: RouteHop,
 182         /// Minimal fees required to route to the source node of the current hop via any of its inbound channels.
 183         src_lowest_inbound_fees: RoutingFees,
 184         /// Fees of the channel used in this hop.
 185         channel_fees: RoutingFees,
 186         /// All the fees paid *after* this channel on the way to the destination
 187         next_hops_fee_msat: u64,
 188         /// Fee paid for the use of the current channel (see channel_fees).
 189         /// The value will be actually deducted from the counterparty balance on the previous link.
 190         hop_use_fee_msat: u64,
 191         /// Used to compare channels when choosing the for routing.
 192         /// Includes paying for the use of a hop and the following hops, as well as
 193         /// an estimated cost of reaching this hop.
 194         /// Might get stale when fees are recomputed. Primarily for internal use.
 195         total_fee_msat: u64,
 196         /// This is useful for update_value_and_recompute_fees to make sure
 197         /// we don't fall below the minimum. Should not be updated manually and
 198         /// generally should not be accessed.
 199         htlc_minimum_msat: u64,
 200         /// A mirror of the same field in RouteGraphNode. Note that this is only used during the graph
 201         /// walk and may be invalid thereafter.
 202         path_htlc_minimum_msat: u64,
 203         /// If we've already processed a node as the best node, we shouldn't process it again. Normally
 204         /// we'd just ignore it if we did as all channels would have a higher new fee, but because we
 205         /// may decrease the amounts in use as we walk the graph, the actual calculated fee may
 206         /// decrease as well. Thus, we have to explicitly track which nodes have been processed and
 207         /// avoid processing them again.
 208         was_processed: bool,
 209 }
 210
 211 // Instantiated with a list of hops with correct data in them collected during path finding,
 212 // an instance of this struct should be further modified only via given methods.
 213 #[derive(Clone)]
 214 struct PaymentPath {
 215         hops: Vec<PathBuildingHop>,
 216 }
 217
 218 impl PaymentPath {
 219
 220         // TODO: Add a value_msat field to PaymentPath and use it instead of this function.
 221         fn get_value_msat(&self) -> u64 {
 222                 self.hops.last().unwrap().route_hop.fee_msat
 223         }
 224
 225         fn get_total_fee_paid_msat(&self) -> u64 {
 226                 if self.hops.len() < 1 {
 227                         return 0;
 228                 }
 229                 let mut result = 0;
 230                 // Can't use next_hops_fee_msat because it gets outdated.
 231                 for (i, hop) in self.hops.iter().enumerate() {
 232                         if i != self.hops.len() - 1 {
 233                                 result += hop.route_hop.fee_msat;
 234                         }
 235                 }
 236                 return result;
 237         }
 238
 239         // If the amount transferred by the path is updated, the fees should be adjusted. Any other way
 240         // to change fees may result in an inconsistency.
 241         //
 242         // Sometimes we call this function right after constructing a path which has inconsistent
 243         // (in terms of reaching htlc_minimum_msat), so that this function puts the fees in order.
 244         // In that case we call it on the "same" amount we initially allocated for this path, and which
 245         // could have been reduced on the way. In that case, there is also a risk of exceeding
 246         // available_liquidity inside this function, because the function is unaware of this bound.
 247         // In our specific recomputation cases where we never increase the value the risk is pretty low.
 248         // This function, however, does not support arbitrarily increasing the value being transferred,
 249         // and the exception will be triggered.
 250         fn update_value_and_recompute_fees(&mut self, value_msat: u64) {
 251                 assert!(value_msat <= self.hops.last().unwrap().route_hop.fee_msat);
 252
 253                 let mut total_fee_paid_msat = 0 as u64;
 254                 for i in (0..self.hops.len()).rev() {
 255                         let last_hop = i == self.hops.len() - 1;
 256
 257                         // For non-last-hop, this value will represent the fees paid on the current hop. It
 258                         // will consist of the fees for the use of the next hop, and extra fees to match
 259                         // htlc_minimum_msat of the current channel. Last hop is handled separately.
 260                         let mut cur_hop_fees_msat = 0;
 261                         if !last_hop {
 262                                 cur_hop_fees_msat = self.hops.get(i + 1).unwrap().hop_use_fee_msat;
 263                         }
 264
 265                         let mut cur_hop = self.hops.get_mut(i).unwrap();
 266                         cur_hop.next_hops_fee_msat = total_fee_paid_msat;
 267                         // Overpay in fees if we can't save these funds due to htlc_minimum_msat.
 268                         // We try to account for htlc_minimum_msat in scoring (add_entry!), so that nodes don't
 269                         // set it too high just to maliciously take more fees by exploiting this
 270                         // match htlc_minimum_msat logic.
 271                         let mut cur_hop_transferred_amount_msat = total_fee_paid_msat + value_msat;
 272                         if let Some(extra_fees_msat) = cur_hop.htlc_minimum_msat.checked_sub(cur_hop_transferred_amount_msat) {
 273                                 // Note that there is a risk that *previous hops* (those closer to us, as we go
 274                                 // payee->our_node here) would exceed their htlc_maximum_msat or available balance.
 275                                 //
 276                                 // This might make us end up with a broken route, although this should be super-rare
 277                                 // in practice, both because of how healthy channels look like, and how we pick
 278                                 // channels in add_entry.
 279                                 // Also, this can't be exploited more heavily than *announce a free path and fail
 280                                 // all payments*.
 281                                 cur_hop_transferred_amount_msat += extra_fees_msat;
 282                                 total_fee_paid_msat += extra_fees_msat;
 283                                 cur_hop_fees_msat += extra_fees_msat;
 284                         }
 285
 286                         if last_hop {
 287                                 // Final hop is a special case: it usually has just value_msat (by design), but also
 288                                 // it still could overpay for the htlc_minimum_msat.
 289                                 cur_hop.route_hop.fee_msat = cur_hop_transferred_amount_msat;
 290                         } else {
 291                                 // Propagate updated fees for the use of the channels to one hop back, where they
 292                                 // will be actually paid (fee_msat). The last hop is handled above separately.
 293                                 cur_hop.route_hop.fee_msat = cur_hop_fees_msat;
 294                         }
 295
 296                         // Fee for the use of the current hop which will be deducted on the previous hop.
 297                         // Irrelevant for the first hop, as it doesn't have the previous hop, and the use of
 298                         // this channel is free for us.
 299                         if i != 0 {
 300                                 if let Some(new_fee) = compute_fees(cur_hop_transferred_amount_msat, cur_hop.channel_fees) {
 301                                         cur_hop.hop_use_fee_msat = new_fee;
 302                                         total_fee_paid_msat += new_fee;
 303                                 } else {
 304                                         // It should not be possible because this function is called only to reduce the
 305                                         // value. In that case, compute_fee was already called with the same fees for
 306                                         // larger amount and there was no overflow.
 307                                         unreachable!();
 308                                 }
 309                         }
 310                 }
 311         }
 312 }
 313
 314 fn compute_fees(amount_msat: u64, channel_fees: RoutingFees) -> Option<u64> {
 315         let proportional_fee_millions =
 316                 amount_msat.checked_mul(channel_fees.proportional_millionths as u64);
 317         if let Some(new_fee) = proportional_fee_millions.and_then(|part| {
 318                         (channel_fees.base_msat as u64).checked_add(part / 1_000_000) }) {
 319
 320                 Some(new_fee)
 321         } else {
 322                 // This function may be (indirectly) called without any verification,
 323                 // with channel_fees provided by a caller. We should handle it gracefully.
 324                 None
 325         }
 326 }
 327
 328 /// Gets a route from us (payer) to the given target node (payee).
 329 ///
 330 /// If the payee provided features in their invoice, they should be provided via payee_features.
 331 /// Without this, MPP will only be used if the payee's features are available in the network graph.
 332 ///
 333 /// Extra routing hops between known nodes and the target will be used if they are included in
 334 /// last_hops.
 335 ///
 336 /// If some channels aren't announced, it may be useful to fill in a first_hops with the
 337 /// results from a local ChannelManager::list_usable_channels() call. If it is filled in, our
 338 /// view of our local channels (from net_graph_msg_handler) will be ignored, and only those
 339 /// in first_hops will be used.
 340 ///
 341 /// Panics if first_hops contains channels without short_channel_ids
 342 /// (ChannelManager::list_usable_channels will never include such channels).
 343 ///
 344 /// The fees on channels from us to next-hops are ignored (as they are assumed to all be
 345 /// equal), however the enabled/disabled bit on such channels as well as the
 346 /// htlc_minimum_msat/htlc_maximum_msat *are* checked as they may change based on the receiving node.
 347 pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, payee: &PublicKey, payee_features: Option<InvoiceFeatures>, first_hops: Option<&[&ChannelDetails]>,
 348         last_hops: &[&RouteHint], final_value_msat: u64, final_cltv: u32, logger: L) -> Result<Route, LightningError> where L::Target: Logger {
 349         // TODO: Obviously *only* using total fee cost sucks. We should consider weighting by
 350         // uptime/success in using a node in the past.
 351         if *payee == *our_node_id {
 352                 return Err(LightningError{err: "Cannot generate a route to ourselves".to_owned(), action: ErrorAction::IgnoreError});
 353         }
 354
 355         if final_value_msat > MAX_VALUE_MSAT {
 356                 return Err(LightningError{err: "Cannot generate a route of more value than all existing satoshis".to_owned(), action: ErrorAction::IgnoreError});
 357         }
 358
 359         if final_value_msat == 0 {
 360                 return Err(LightningError{err: "Cannot send a payment of 0 msat".to_owned(), action: ErrorAction::IgnoreError});
 361         }
 362
 363         for last_hop in last_hops {
 364                 if last_hop.src_node_id == *payee {
 365                         return Err(LightningError{err: "Last hop cannot have a payee as a source.".to_owned(), action: ErrorAction::IgnoreError});
 366                 }
 367         }
 368
 369         // The general routing idea is the following:
 370         // 1. Fill first/last hops communicated by the caller.
 371         // 2. Attempt to construct a path from payer to payee for transferring
 372         //    any ~sufficient (described later) value.
 373         //    If succeed, remember which channels were used and how much liquidity they have available,
 374         //    so that future paths don't rely on the same liquidity.
 375         // 3. Prooceed to the next step if:
 376         //    - we hit the recommended target value;
 377         //    - OR if we could not construct a new path. Any next attempt will fail too.
 378         //    Otherwise, repeat step 2.
 379         // 4. See if we managed to collect paths which aggregately are able to transfer target value
 380         //    (not recommended value). If yes, proceed. If not, fail routing.
 381         // 5. Randomly combine paths into routes having enough to fulfill the payment. (TODO: knapsack)
 382         // 6. Of all the found paths, select only those with the lowest total fee.
 383         // 7. The last path in every selected route is likely to be more than we need.
 384         //    Reduce its value-to-transfer and recompute fees.
 385         // 8. Choose the best route by the lowest total fee.
 386
 387         // As for the actual search algorithm,
 388         // we do a payee-to-payer pseudo-Dijkstra's sorting by each node's distance from the payee
 389         // plus the minimum per-HTLC fee to get from it to another node (aka "shitty pseudo-A*").
 390         //
 391         // We are not a faithful Dijkstra's implementation because we can change values which impact
 392         // earlier nodes while processing later nodes. Specifically, if we reach a channel with a lower
 393         // liquidity limit (via htlc_maximum_msat, on-chain capacity or assumed liquidity limits) then
 394         // the value we are currently attempting to send over a path, we simply reduce the value being
 395         // sent along the path for any hops after that channel. This may imply that later fees (which
 396         // we've already tabulated) are lower because a smaller value is passing through the channels
 397         // (and the proportional fee is thus lower). There isn't a trivial way to recalculate the
 398         // channels which were selected earlier (and which may still be used for other paths without a
 399         // lower liquidity limit), so we simply accept that some liquidity-limited paths may be
 400         // de-preferenced.
 401         //
 402         // One potentially problematic case for this algorithm would be if there are many
 403         // liquidity-limited paths which are liquidity-limited near the destination (ie early in our
 404         // graph walking), we may never find a liquidity-unlimited path which has lower proportional
 405         // fee (and only lower absolute fee when considering the ultimate value sent). Because we only
 406         // consider paths with at least 5% of the total value being sent, the damage from such a case
 407         // should be limited, however this could be further reduced in the future by calculating fees
 408         // on the amount we wish to route over a path, not the amount we are routing over a path.
 409         //
 410         // Alternatively, we could store more detailed path information in the heap (targets, below)
 411         // and index the best-path map (dist, below) by node *and* HTLC limits, however that would blow
 412         // up the runtime significantly both algorithmically (as we'd traverse nodes multiple times)
 413         // and practically (as we would need to store dynamically-allocated path information in heap
 414         // objects, increasing malloc traffic and indirect memory access significantly). Further, the
 415         // results of such an algorithm would likely be biased towards lower-value paths.
 416         //
 417         // Further, we could return to a faithful Dijkstra's algorithm by rejecting paths with limits
 418         // outside of our current search value, running a path search more times to gather candidate
 419         // paths at different values. While this may be acceptable, further path searches may increase
 420         // runtime for little gain. Specifically, the current algorithm rather efficiently explores the
 421         // graph for candidate paths, calculating the maximum value which can realistically be sent at
 422         // the same time, remaining generic across different payment values.
 423         //
 424         // TODO: There are a few tweaks we could do, including possibly pre-calculating more stuff
 425         // to use as the A* heuristic beyond just the cost to get one node further than the current
 426         // one.
 427
 428         let dummy_directional_info = DummyDirectionalChannelInfo { // used for first_hops routes
 429                 cltv_expiry_delta: 0,
 430                 htlc_minimum_msat: 0,
 431                 htlc_maximum_msat: None,
 432                 fees: RoutingFees {
 433                         base_msat: 0,
 434                         proportional_millionths: 0,
 435                 }
 436         };
 437
 438         let mut targets = BinaryHeap::new(); //TODO: Do we care about switching to eg Fibbonaci heap?
 439         let mut dist = HashMap::with_capacity(network.get_nodes().len());
 440
 441         // During routing, if we ignore a path due to an htlc_minimum_msat limit, we set this,
 442         // indicating that we may wish to try again with a higher value, potentially paying to meet an
 443         // htlc_minimum with extra fees while still finding a cheaper path.
 444         let mut hit_minimum_limit;
 445
 446         // When arranging a route, we select multiple paths so that we can make a multi-path payment.
 447         // We start with a path_value of the exact amount we want, and if that generates a route we may
 448         // return it immediately. Otherwise, we don't stop searching for paths until we have 3x the
 449         // amount we want in total across paths, selecting the best subset at the end.
 450         const ROUTE_CAPACITY_PROVISION_FACTOR: u64 = 3;
 451         let recommended_value_msat = final_value_msat * ROUTE_CAPACITY_PROVISION_FACTOR as u64;
 452         let mut path_value_msat = final_value_msat;
 453
 454         // Allow MPP only if we have a features set from somewhere that indicates the payee supports
 455         // it. If the payee supports it they're supposed to include it in the invoice, so that should
 456         // work reliably.
 457         let allow_mpp = if let Some(features) = &payee_features {
 458                 features.supports_basic_mpp()
 459         } else if let Some(node) = network.get_nodes().get(&payee) {
 460                 if let Some(node_info) = node.announcement_info.as_ref() {
 461                         node_info.features.supports_basic_mpp()
 462                 } else { false }
 463         } else { false };
 464
 465         // Step (1).
 466         // Prepare the data we'll use for payee-to-payer search by
 467         // inserting first hops suggested by the caller as targets.
 468         // Our search will then attempt to reach them while traversing from the payee node.
 469         let mut first_hop_targets = HashMap::with_capacity(if first_hops.is_some() { first_hops.as_ref().unwrap().len() } else { 0 });
 470         if let Some(hops) = first_hops {
 471                 for chan in hops {
 472                         let short_channel_id = chan.short_channel_id.expect("first_hops should be filled in with usable channels, not pending ones");
 473                         if chan.remote_network_id == *our_node_id {
 474                                 return Err(LightningError{err: "First hop cannot have our_node_id as a destination.".to_owned(), action: ErrorAction::IgnoreError});
 475                         }
 476                         first_hop_targets.insert(chan.remote_network_id, (short_channel_id, chan.counterparty_features.clone(), chan.outbound_capacity_msat));
 477                 }
 478                 if first_hop_targets.is_empty() {
 479                         return Err(LightningError{err: "Cannot route when there are no outbound routes away from us".to_owned(), action: ErrorAction::IgnoreError});
 480                 }
 481         }
 482
 483         // We don't want multiple paths (as per MPP) share liquidity of the same channels.
 484         // This map allows paths to be aware of the channel use by other paths in the same call.
 485         // This would help to make a better path finding decisions and not "overbook" channels.
 486         // It is unaware of the directions (except for `outbound_capacity_msat` in `first_hops`).
 487         let mut bookkeeped_channels_liquidity_available_msat = HashMap::new();
 488
 489         // Keeping track of how much value we already collected across other paths. Helps to decide:
 490         // - how much a new path should be transferring (upper bound);
 491         // - whether a channel should be disregarded because
 492         //   it's available liquidity is too small comparing to how much more we need to collect;
 493         // - when we want to stop looking for new paths.
 494         let mut already_collected_value_msat = 0;
 495
 496         macro_rules! add_entry {
 497                 // Adds entry which goes from $src_node_id to $dest_node_id
 498                 // over the channel with id $chan_id with fees described in
 499                 // $directional_info.
 500                 // $next_hops_fee_msat represents the fees paid for using all the channel *after* this one,
 501                 // since that value has to be transferred over this channel.
 502                 ( $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,
 503                    $next_hops_value_contribution: expr, $incl_fee_next_hops_htlc_minimum_msat: expr ) => {
 504                         // Channels to self should not be used. This is more of belt-and-suspenders, because in
 505                         // practice these cases should be caught earlier:
 506                         // - for regular channels at channel announcement (TODO)
 507                         // - for first and last hops early in get_route
 508                         if $src_node_id != $dest_node_id.clone() {
 509                                 let available_liquidity_msat = bookkeeped_channels_liquidity_available_msat.entry($chan_id.clone()).or_insert_with(|| {
 510                                         let mut initial_liquidity_available_msat = None;
 511                                         if let Some(capacity_sats) = $capacity_sats {
 512                                                 initial_liquidity_available_msat = Some(capacity_sats * 1000);
 513                                         }
 514
 515                                         if let Some(htlc_maximum_msat) = $directional_info.htlc_maximum_msat {
 516                                                 if let Some(available_msat) = initial_liquidity_available_msat {
 517                                                         initial_liquidity_available_msat = Some(cmp::min(available_msat, htlc_maximum_msat));
 518                                                 } else {
 519                                                         initial_liquidity_available_msat = Some(htlc_maximum_msat);
 520                                                 }
 521                                         }
 522
 523                                         match initial_liquidity_available_msat {
 524                                                 Some(available_msat) => available_msat,
 525                                                 // We assume channels with unknown balance have
 526                                                 // a capacity of 0.0025 BTC (or 250_000 sats).
 527                                                 None => 250_000 * 1000
 528                                         }
 529                                 });
 530
 531                                 // It is tricky to substract $next_hops_fee_msat from available liquidity here.
 532                                 // It may be misleading because we might later choose to reduce the value transferred
 533                                 // over these channels, and the channel which was insufficient might become sufficient.
 534                                 // Worst case: we drop a good channel here because it can't cover the high following
 535                                 // fees caused by one expensive channel, but then this channel could have been used
 536                                 // if the amount being transferred over this path is lower.
 537                                 // We do this for now, but this is a subject for removal.
 538                                 if let Some(available_value_contribution_msat) = available_liquidity_msat.checked_sub($next_hops_fee_msat) {
 539
 540                                         // Routing Fragmentation Mitigation heuristic:
 541                                         //
 542                                         // Routing fragmentation across many payment paths increases the overall routing
 543                                         // fees as you have irreducible routing fees per-link used (`fee_base_msat`).
 544                                         // Taking too many smaller paths also increases the chance of payment failure.
 545                                         // Thus to avoid this effect, we require from our collected links to provide
 546                                         // at least a minimal contribution to the recommended value yet-to-be-fulfilled.
 547                                         //
 548                                         // This requirement is currently 5% of the remaining-to-be-collected value.
 549                                         // This means as we successfully advance in our collection,
 550                                         // the absolute liquidity contribution is lowered,
 551                                         // thus increasing the number of potential channels to be selected.
 552
 553                                         // Derive the minimal liquidity contribution with a ratio of 20 (5%, rounded up)
 554                                         // or 100% if we're not allowed to do multipath payments.
 555                                         let minimal_value_contribution_msat: u64 = if allow_mpp {
 556                                                 (recommended_value_msat - already_collected_value_msat + 19) / 20
 557                                         } else {
 558                                                 final_value_msat
 559                                         };
 560                                         // Verify the liquidity offered by this channel complies to the minimal contribution.
 561                                         let contributes_sufficient_value = available_value_contribution_msat >= minimal_value_contribution_msat;
 562
 563                                         let value_contribution_msat = cmp::min(available_value_contribution_msat, $next_hops_value_contribution);
 564                                         // Includes paying fees for the use of the following channels.
 565                                         let amount_to_transfer_over_msat: u64 = match value_contribution_msat.checked_add($next_hops_fee_msat) {
 566                                                 Some(result) => result,
 567                                                 // Can't overflow due to how the values were computed right above.
 568                                                 None => unreachable!(),
 569                                         };
 570                                         #[allow(unused_comparisons)] // $incl_fee_next_hops_htlc_minimum_msat is 0 in some calls so rustc complains
 571                                         let over_path_minimum_msat = amount_to_transfer_over_msat >= $directional_info.htlc_minimum_msat &&
 572                                                 amount_to_transfer_over_msat >= $incl_fee_next_hops_htlc_minimum_msat;
 573
 574                                         // If HTLC minimum is larger than the amount we're going to transfer, we shouldn't
 575                                         // bother considering this channel.
 576                                         // Since we're choosing amount_to_transfer_over_msat as maximum possible, it can
 577                                         // be only reduced later (not increased), so this channel should just be skipped
 578                                         // as not sufficient.
 579                                         if !over_path_minimum_msat {
 580                                                 hit_minimum_limit = true;
 581                                         } else if contributes_sufficient_value {
 582                                                 // Note that low contribution here (limited by available_liquidity_msat)
 583                                                 // might violate htlc_minimum_msat on the hops which are next along the
 584                                                 // payment path (upstream to the payee). To avoid that, we recompute path
 585                                                 // path fees knowing the final path contribution after constructing it.
 586                                                 let path_htlc_minimum_msat = match compute_fees($incl_fee_next_hops_htlc_minimum_msat, $directional_info.fees)
 587                                                                 .map(|fee_msat| fee_msat.checked_add($incl_fee_next_hops_htlc_minimum_msat)) {
 588                                                         Some(Some(value_msat)) => cmp::max(value_msat, $directional_info.htlc_minimum_msat),
 589                                                         _ => u64::max_value()
 590                                                 };
 591                                                 let hm_entry = dist.entry(&$src_node_id);
 592                                                 let old_entry = hm_entry.or_insert_with(|| {
 593                                                         // If there was previously no known way to access
 594                                                         // the source node (recall it goes payee-to-payer) of $chan_id, first add
 595                                                         // a semi-dummy record just to compute the fees to reach the source node.
 596                                                         // This will affect our decision on selecting $chan_id
 597                                                         // as a way to reach the $dest_node_id.
 598                                                         let mut fee_base_msat = u32::max_value();
 599                                                         let mut fee_proportional_millionths = u32::max_value();
 600                                                         if let Some(Some(fees)) = network.get_nodes().get(&$src_node_id).map(|node| node.lowest_inbound_channel_fees) {
 601                                                                 fee_base_msat = fees.base_msat;
 602                                                                 fee_proportional_millionths = fees.proportional_millionths;
 603                                                         }
 604                                                         PathBuildingHop {
 605                                                                 route_hop: RouteHop {
 606                                                                         pubkey: $dest_node_id.clone(),
 607                                                                         node_features: NodeFeatures::empty(),
 608                                                                         short_channel_id: 0,
 609                                                                         channel_features: $chan_features.clone(),
 610                                                                         fee_msat: 0,
 611                                                                         cltv_expiry_delta: 0,
 612                                                                 },
 613                                                                 src_lowest_inbound_fees: RoutingFees {
 614                                                                         base_msat: fee_base_msat,
 615                                                                         proportional_millionths: fee_proportional_millionths,
 616                                                                 },
 617                                                                 channel_fees: $directional_info.fees,
 618                                                                 next_hops_fee_msat: u64::max_value(),
 619                                                                 hop_use_fee_msat: u64::max_value(),
 620                                                                 total_fee_msat: u64::max_value(),
 621                                                                 htlc_minimum_msat: $directional_info.htlc_minimum_msat,
 622                                                                 path_htlc_minimum_msat,
 623                                                                 was_processed: false,
 624                                                         }
 625                                                 });
 626
 627                                                 if !old_entry.was_processed {
 628                                                         let mut hop_use_fee_msat = 0;
 629                                                         let mut total_fee_msat = $next_hops_fee_msat;
 630
 631                                                         // Ignore hop_use_fee_msat for channel-from-us as we assume all channels-from-us
 632                                                         // will have the same effective-fee
 633                                                         if $src_node_id != *our_node_id {
 634                                                                 match compute_fees(amount_to_transfer_over_msat, $directional_info.fees) {
 635                                                                         // max_value means we'll always fail
 636                                                                         // the old_entry.total_fee_msat > total_fee_msat check
 637                                                                         None => total_fee_msat = u64::max_value(),
 638                                                                         Some(fee_msat) => {
 639                                                                                 hop_use_fee_msat = fee_msat;
 640                                                                                 total_fee_msat += hop_use_fee_msat;
 641                                                                                 match compute_fees(minimal_value_contribution_msat, old_entry.src_lowest_inbound_fees).map(|a| a.checked_add(total_fee_msat)) {
 642                                                                                         Some(Some(v)) => {
 643                                                                                                 total_fee_msat = v;
 644                                                                                         },
 645                                                                                         _ => {
 646                                                                                                 total_fee_msat = u64::max_value();
 647                                                                                         }
 648                                                                                 };
 649                                                                         }
 650                                                                 }
 651                                                         }
 652
 653                                                         let new_graph_node = RouteGraphNode {
 654                                                                 pubkey: $src_node_id,
 655                                                                 lowest_fee_to_peer_through_node: total_fee_msat,
 656                                                                 lowest_fee_to_node: $next_hops_fee_msat as u64 + hop_use_fee_msat,
 657                                                                 value_contribution_msat: value_contribution_msat,
 658                                                                 path_htlc_minimum_msat,
 659                                                         };
 660
 661                                                         // Update the way of reaching $src_node_id with the given $chan_id (from $dest_node_id),
 662                                                         // if this way is cheaper than the already known
 663                                                         // (considering the cost to "reach" this channel from the route destination,
 664                                                         // the cost of using this channel,
 665                                                         // and the cost of routing to the source node of this channel).
 666                                                         // Also, consider that htlc_minimum_msat_difference, because we might end up
 667                                                         // paying it. Consider the following exploit:
 668                                                         // we use 2 paths to transfer 1.5 BTC. One of them is 0-fee normal 1 BTC path,
 669                                                         // and for the other one we picked a 1sat-fee path with htlc_minimum_msat of
 670                                                         // 1 BTC. Now, since the latter is more expensive, we gonna try to cut it
 671                                                         // by 0.5 BTC, but then match htlc_minimum_msat by paying a fee of 0.5 BTC
 672                                                         // to this channel.
 673                                                         // Ideally the scoring could be smarter (e.g. 0.5*htlc_minimum_msat here),
 674                                                         // but it may require additional tracking - we don't want to double-count
 675                                                         // the fees included in $incl_fee_next_hops_htlc_minimum_msat, but also
 676                                                         // can't use something that may decrease on future hops.
 677                                                         let old_cost = cmp::max(old_entry.total_fee_msat, old_entry.path_htlc_minimum_msat);
 678                                                         let new_cost = cmp::max(total_fee_msat, path_htlc_minimum_msat);
 679
 680                                                         if new_cost < old_cost {
 681                                                                 targets.push(new_graph_node);
 682                                                                 old_entry.next_hops_fee_msat = $next_hops_fee_msat;
 683                                                                 old_entry.hop_use_fee_msat = hop_use_fee_msat;
 684                                                                 old_entry.total_fee_msat = total_fee_msat;
 685                                                                 old_entry.route_hop = RouteHop {
 686                                                                         pubkey: $dest_node_id.clone(),
 687                                                                         node_features: NodeFeatures::empty(),
 688                                                                         short_channel_id: $chan_id.clone(),
 689                                                                         channel_features: $chan_features.clone(),
 690                                                                         fee_msat: 0, // This value will be later filled with hop_use_fee_msat of the following channel
 691                                                                         cltv_expiry_delta: $directional_info.cltv_expiry_delta as u32,
 692                                                                 };
 693                                                                 old_entry.channel_fees = $directional_info.fees;
 694                                                                 old_entry.htlc_minimum_msat = $directional_info.htlc_minimum_msat;
 695                                                                 old_entry.path_htlc_minimum_msat = path_htlc_minimum_msat;
 696                                                         }
 697                                                 }
 698                                         }
 699                                 }
 700                         }
 701                 };
 702         }
 703
 704         // Find ways (channels with destination) to reach a given node and store them
 705         // in the corresponding data structures (routing graph etc).
 706         // $fee_to_target_msat represents how much it costs to reach to this node from the payee,
 707         // meaning how much will be paid in fees after this node (to the best of our knowledge).
 708         // This data can later be helpful to optimize routing (pay lower fees).
 709         macro_rules! add_entries_to_cheapest_to_target_node {
 710                 ( $node: expr, $node_id: expr, $fee_to_target_msat: expr, $next_hops_value_contribution: expr, $incl_fee_next_hops_htlc_minimum_msat: expr ) => {
 711                         let skip_node = if let Some(elem) = dist.get_mut($node_id) {
 712                                 let v = elem.was_processed;
 713                                 elem.was_processed = true;
 714                                 v
 715                         } else {
 716                                 // Entries are added to dist in add_entry!() when there is a channel from a node.
 717                                 // Because there are no channels from payee, it will not have a dist entry at this point.
 718                                 // If we're processing any other node, it is always be the result of a channel from it.
 719                                 assert_eq!($node_id, payee);
 720                                 false
 721                         };
 722
 723                         if !skip_node && first_hops.is_some() {
 724                                 if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat)) = first_hop_targets.get(&$node_id) {
 725                                         add_entry!(first_hop, *our_node_id, $node_id, dummy_directional_info, Some(outbound_capacity_msat / 1000), features.to_context(), $fee_to_target_msat, $next_hops_value_contribution, $incl_fee_next_hops_htlc_minimum_msat);
 726                                 }
 727                         }
 728
 729                         let features;
 730                         if let Some(node_info) = $node.announcement_info.as_ref() {
 731                                 features = node_info.features.clone();
 732                         } else {
 733                                 features = NodeFeatures::empty();
 734                         }
 735
 736                         if !skip_node && !features.requires_unknown_bits() {
 737                                 for chan_id in $node.channels.iter() {
 738                                         let chan = network.get_channels().get(chan_id).unwrap();
 739                                         if !chan.features.requires_unknown_bits() {
 740                                                 if chan.node_one == *$node_id {
 741                                                         // ie $node is one, ie next hop in A* is two, via the two_to_one channel
 742                                                         if first_hops.is_none() || chan.node_two != *our_node_id {
 743                                                                 if let Some(two_to_one) = chan.two_to_one.as_ref() {
 744                                                                         if two_to_one.enabled {
 745                                                                                 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, $incl_fee_next_hops_htlc_minimum_msat);
 746                                                                         }
 747                                                                 }
 748                                                         }
 749                                                 } else {
 750                                                         if first_hops.is_none() || chan.node_one != *our_node_id {
 751                                                                 if let Some(one_to_two) = chan.one_to_two.as_ref() {
 752                                                                         if one_to_two.enabled {
 753                                                                                 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, $incl_fee_next_hops_htlc_minimum_msat);
 754                                                                         }
 755                                                                 }
 756
 757                                                         }
 758                                                 }
 759                                         }
 760                                 }
 761                         }
 762                 };
 763         }
 764
 765         let mut payment_paths = Vec::<PaymentPath>::new();
 766
 767         // TODO: diversify by nodes (so that all paths aren't doomed if one node is offline).
 768         'paths_collection: loop {
 769                 // For every new path, start from scratch, except
 770                 // bookkeeped_channels_liquidity_available_msat, which will improve
 771                 // the further iterations of path finding. Also don't erase first_hop_targets.
 772                 targets.clear();
 773                 dist.clear();
 774                 hit_minimum_limit = false;
 775
 776                 // If first hop is a private channel and the only way to reach the payee, this is the only
 777                 // place where it could be added.
 778                 if first_hops.is_some() {
 779                         if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat)) = first_hop_targets.get(&payee) {
 780                                 add_entry!(first_hop, *our_node_id, payee, dummy_directional_info, Some(outbound_capacity_msat / 1000), features.to_context(), 0, path_value_msat, 0);
 781                         }
 782                 }
 783
 784                 // Add the payee as a target, so that the payee-to-payer
 785                 // search algorithm knows what to start with.
 786                 match network.get_nodes().get(payee) {
 787                         // The payee is not in our network graph, so nothing to add here.
 788                         // There is still a chance of reaching them via last_hops though,
 789                         // so don't yet fail the payment here.
 790                         // If not, targets.pop() will not even let us enter the loop in step 2.
 791                         None => {},
 792                         Some(node) => {
 793                                 add_entries_to_cheapest_to_target_node!(node, payee, 0, path_value_msat, 0);
 794                         },
 795                 }
 796
 797                 // Step (1).
 798                 // If a caller provided us with last hops, add them to routing targets. Since this happens
 799                 // earlier than general path finding, they will be somewhat prioritized, although currently
 800                 // it matters only if the fees are exactly the same.
 801                 for hop in last_hops.iter() {
 802                         let have_hop_src_in_graph =
 803                                 if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat)) = first_hop_targets.get(&hop.src_node_id) {
 804                                         // If this hop connects to a node with which we have a direct channel, ignore
 805                                         // the network graph and add both the hop and our direct channel to
 806                                         // the candidate set.
 807                                         //
 808                                         // Currently there are no channel-context features defined, so we are a
 809                                         // bit lazy here. In the future, we should pull them out via our
 810                                         // ChannelManager, but there's no reason to waste the space until we
 811                                         // need them.
 812                                         add_entry!(first_hop, *our_node_id , hop.src_node_id, dummy_directional_info, Some(outbound_capacity_msat / 1000), features.to_context(), 0, path_value_msat, 0);
 813                                         true
 814                                 } else {
 815                                         // In any other case, only add the hop if the source is in the regular network
 816                                         // graph:
 817                                         network.get_nodes().get(&hop.src_node_id).is_some()
 818                                 };
 819                         if have_hop_src_in_graph {
 820                                 // BOLT 11 doesn't allow inclusion of features for the last hop hints, which
 821                                 // really sucks, cause we're gonna need that eventually.
 822                                 let last_path_htlc_minimum_msat: u64 = match hop.htlc_minimum_msat {
 823                                         Some(htlc_minimum_msat) => htlc_minimum_msat,
 824                                         None => 0
 825                                 };
 826                                 let directional_info = DummyDirectionalChannelInfo {
 827                                         cltv_expiry_delta: hop.cltv_expiry_delta as u32,
 828                                         htlc_minimum_msat: last_path_htlc_minimum_msat,
 829                                         htlc_maximum_msat: hop.htlc_maximum_msat,
 830                                         fees: hop.fees,
 831                                 };
 832                                 add_entry!(hop.short_channel_id, hop.src_node_id, payee, directional_info, None::<u64>, ChannelFeatures::empty(), 0, path_value_msat, 0);
 833                         }
 834                 }
 835
 836                 // At this point, targets are filled with the data from first and
 837                 // last hops communicated by the caller, and the payment receiver.
 838                 let mut found_new_path = false;
 839
 840                 // Step (2).
 841                 // If this loop terminates due the exhaustion of targets, two situations are possible:
 842                 // - not enough outgoing liquidity:
 843                 //   0 < already_collected_value_msat < final_value_msat
 844                 // - enough outgoing liquidity:
 845                 //   final_value_msat <= already_collected_value_msat < recommended_value_msat
 846                 // Both these cases (and other cases except reaching recommended_value_msat) mean that
 847                 // paths_collection will be stopped because found_new_path==false.
 848                 // This is not necessarily a routing failure.
 849                 'path_construction: while let Some(RouteGraphNode { pubkey, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat, .. }) = targets.pop() {
 850
 851                         // Since we're going payee-to-payer, hitting our node as a target means we should stop
 852                         // traversing the graph and arrange the path out of what we found.
 853                         if pubkey == *our_node_id {
 854                                 let mut new_entry = dist.remove(&our_node_id).unwrap();
 855                                 let mut ordered_hops = vec!(new_entry.clone());
 856
 857                                 'path_walk: loop {
 858                                         if let Some(&(_, ref features, _)) = first_hop_targets.get(&ordered_hops.last().unwrap().route_hop.pubkey) {
 859                                                 ordered_hops.last_mut().unwrap().route_hop.node_features = features.to_context();
 860                                         } else if let Some(node) = network.get_nodes().get(&ordered_hops.last().unwrap().route_hop.pubkey) {
 861                                                 if let Some(node_info) = node.announcement_info.as_ref() {
 862                                                         ordered_hops.last_mut().unwrap().route_hop.node_features = node_info.features.clone();
 863                                                 } else {
 864                                                         ordered_hops.last_mut().unwrap().route_hop.node_features = NodeFeatures::empty();
 865                                                 }
 866                                         } else {
 867                                                 // We should be able to fill in features for everything except the last
 868                                                 // hop, if the last hop was provided via a BOLT 11 invoice (though we
 869                                                 // should be able to extend it further as BOLT 11 does have feature
 870                                                 // flags for the last hop node itself).
 871                                                 assert!(ordered_hops.last().unwrap().route_hop.pubkey == *payee);
 872                                         }
 873
 874                                         // Means we succesfully traversed from the payer to the payee, now
 875                                         // save this path for the payment route. Also, update the liquidity
 876                                         // remaining on the used hops, so that we take them into account
 877                                         // while looking for more paths.
 878                                         if ordered_hops.last().unwrap().route_hop.pubkey == *payee {
 879                                                 break 'path_walk;
 880                                         }
 881
 882                                         new_entry = match dist.remove(&ordered_hops.last().unwrap().route_hop.pubkey) {
 883                                                 Some(payment_hop) => payment_hop,
 884                                                 // We can't arrive at None because, if we ever add an entry to targets,
 885                                                 // we also fill in the entry in dist (see add_entry!).
 886                                                 None => unreachable!(),
 887                                         };
 888                                         // We "propagate" the fees one hop backward (topologically) here,
 889                                         // so that fees paid for a HTLC forwarding on the current channel are
 890                                         // associated with the previous channel (where they will be subtracted).
 891                                         ordered_hops.last_mut().unwrap().route_hop.fee_msat = new_entry.hop_use_fee_msat;
 892                                         ordered_hops.last_mut().unwrap().route_hop.cltv_expiry_delta = new_entry.route_hop.cltv_expiry_delta;
 893                                         ordered_hops.push(new_entry.clone());
 894                                 }
 895                                 ordered_hops.last_mut().unwrap().route_hop.fee_msat = value_contribution_msat;
 896                                 ordered_hops.last_mut().unwrap().hop_use_fee_msat = 0;
 897                                 ordered_hops.last_mut().unwrap().route_hop.cltv_expiry_delta = final_cltv;
 898
 899                                 let mut payment_path = PaymentPath {hops: ordered_hops};
 900
 901                                 // We could have possibly constructed a slightly inconsistent path: since we reduce
 902                                 // value being transferred along the way, we could have violated htlc_minimum_msat
 903                                 // on some channels we already passed (assuming dest->source direction). Here, we
 904                                 // recompute the fees again, so that if that's the case, we match the currently
 905                                 // underpaid htlc_minimum_msat with fees.
 906                                 payment_path.update_value_and_recompute_fees(cmp::min(value_contribution_msat, final_value_msat));
 907
 908                                 // Since a path allows to transfer as much value as
 909                                 // the smallest channel it has ("bottleneck"), we should recompute
 910                                 // the fees so sender HTLC don't overpay fees when traversing
 911                                 // larger channels than the bottleneck. This may happen because
 912                                 // when we were selecting those channels we were not aware how much value
 913                                 // this path will transfer, and the relative fee for them
 914                                 // might have been computed considering a larger value.
 915                                 // Remember that we used these channels so that we don't rely
 916                                 // on the same liquidity in future paths.
 917                                 let mut prevented_redundant_path_selection = false;
 918                                 for payment_hop in payment_path.hops.iter() {
 919                                         let channel_liquidity_available_msat = bookkeeped_channels_liquidity_available_msat.get_mut(&payment_hop.route_hop.short_channel_id).unwrap();
 920                                         let mut spent_on_hop_msat = value_contribution_msat;
 921                                         let next_hops_fee_msat = payment_hop.next_hops_fee_msat;
 922                                         spent_on_hop_msat += next_hops_fee_msat;
 923                                         if *channel_liquidity_available_msat < spent_on_hop_msat {
 924                                                 // This should not happen because we do recompute fees right before,
 925                                                 // trying to avoid cases when a hop is not usable due to the fee situation.
 926                                                 break 'path_construction;
 927                                         }
 928                                         if *channel_liquidity_available_msat < path_value_msat {
 929                                                 // If we use at least half of a channel's available liquidity, assume that
 930                                                 // it will not be selected again in the next loop iteration (see below).
 931                                                 prevented_redundant_path_selection = true;
 932                                         }
 933                                         *channel_liquidity_available_msat -= spent_on_hop_msat;
 934                                 }
 935                                 if !prevented_redundant_path_selection {
 936                                         // If we weren't capped by hitting a liquidity limit on a channel in the path,
 937                                         // we'll probably end up picking the same path again on the next iteration.
 938                                         // Randomly decrease the available liquidity of a hop in the middle of the
 939                                         // path.
 940                                         let victim_liquidity = bookkeeped_channels_liquidity_available_msat.get_mut(
 941                                                 &payment_path.hops[(payment_path.hops.len() - 1) / 2].route_hop.short_channel_id).unwrap();
 942                                         *victim_liquidity = 0;
 943                                 }
 944
 945                                 // Track the total amount all our collected paths allow to send so that we:
 946                                 // - know when to stop looking for more paths
 947                                 // - know which of the hops are useless considering how much more sats we need
 948                                 //   (contributes_sufficient_value)
 949                                 already_collected_value_msat += value_contribution_msat;
 950
 951                                 payment_paths.push(payment_path);
 952                                 found_new_path = true;
 953                                 break 'path_construction;
 954                         }
 955
 956                         // If we found a path back to the payee, we shouldn't try to process it again. This is
 957                         // the equivalent of the `elem.was_processed` check in
 958                         // add_entries_to_cheapest_to_target_node!() (see comment there for more info).
 959                         if pubkey == *payee { continue 'path_construction; }
 960
 961                         // Otherwise, since the current target node is not us,
 962                         // keep "unrolling" the payment graph from payee to payer by
 963                         // finding a way to reach the current target from the payer side.
 964                         match network.get_nodes().get(&pubkey) {
 965                                 None => {},
 966                                 Some(node) => {
 967                                         add_entries_to_cheapest_to_target_node!(node, &pubkey, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat);
 968                                 },
 969                         }
 970                 }
 971
 972                 if !allow_mpp {
 973                         // If we don't support MPP, no use trying to gather more value ever.
 974                         break 'paths_collection;
 975                 }
 976
 977                 // Step (3).
 978                 // Stop either when the recommended value is reached or if no new path was found in this
 979                 // iteration.
 980                 // In the latter case, making another path finding attempt won't help,
 981                 // because we deterministically terminated the search due to low liquidity.
 982                 if already_collected_value_msat >= recommended_value_msat || !found_new_path {
 983                         break 'paths_collection;
 984                 }
 985                 // Further, if this was our first walk of the graph, and we weren't limited by an
 986                 // htlc_minim_msat, return immediately because this path should suffice. If we were limited
 987                 // by an htlc_minimum_msat value, find another path with a higher value, potentially
 988                 // allowing us to pay fees to meet the htlc_minimum while still keeping a lower total fee.
 989                 if already_collected_value_msat == final_value_msat && payment_paths.len() == 1 {
 990                         if !hit_minimum_limit {
 991                                 break 'paths_collection;
 992                         }
 993                         path_value_msat = recommended_value_msat;
 994                 }
 995         }
 996
 997         // Step (4).
 998         if payment_paths.len() == 0 {
 999                 return Err(LightningError{err: "Failed to find a path to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1000         }
1001
1002         if already_collected_value_msat < final_value_msat {
1003                 return Err(LightningError{err: "Failed to find a sufficient route to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1004         }
1005
1006         // Sort by total fees and take the best paths.
1007         payment_paths.sort_by_key(|path| path.get_total_fee_paid_msat());
1008         if payment_paths.len() > 50 {
1009                 payment_paths.truncate(50);
1010         }
1011
1012         // Draw multiple sufficient routes by randomly combining the selected paths.
1013         let mut drawn_routes = Vec::new();
1014         for i in 0..payment_paths.len() {
1015                 let mut cur_route = Vec::<PaymentPath>::new();
1016                 let mut aggregate_route_value_msat = 0;
1017
1018                 // Step (5).
1019                 // TODO: real random shuffle
1020                 // Currently just starts with i_th and goes up to i-1_th in a looped way.
1021                 let cur_payment_paths = [&payment_paths[i..], &payment_paths[..i]].concat();
1022
1023                 // Step (6).
1024                 for payment_path in cur_payment_paths {
1025                         cur_route.push(payment_path.clone());
1026                         aggregate_route_value_msat += payment_path.get_value_msat();
1027                         if aggregate_route_value_msat > final_value_msat {
1028                                 // Last path likely overpaid. Substract it from the most expensive
1029                                 // (in terms of proportional fee) path in this route and recompute fees.
1030                                 // This might be not the most economically efficient way, but fewer paths
1031                                 // also makes routing more reliable.
1032                                 let mut overpaid_value_msat = aggregate_route_value_msat - final_value_msat;
1033
1034                                 // First, drop some expensive low-value paths entirely if possible.
1035                                 // Sort by value so that we drop many really-low values first, since
1036                                 // fewer paths is better: the payment is less likely to fail.
1037                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1038                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1039                                 cur_route.sort_by_key(|path| path.get_value_msat());
1040                                 // We should make sure that at least 1 path left.
1041                                 let mut paths_left = cur_route.len();
1042                                 cur_route.retain(|path| {
1043                                         if paths_left == 1 {
1044                                                 return true
1045                                         }
1046                                         let mut keep = true;
1047                                         let path_value_msat = path.get_value_msat();
1048                                         if path_value_msat <= overpaid_value_msat {
1049                                                 keep = false;
1050                                                 overpaid_value_msat -= path_value_msat;
1051                                                 paths_left -= 1;
1052                                         }
1053                                         keep
1054                                 });
1055
1056                                 if overpaid_value_msat == 0 {
1057                                         break;
1058                                 }
1059
1060                                 assert!(cur_route.len() > 0);
1061
1062                                 // Step (7).
1063                                 // Now, substract the overpaid value from the most-expensive path.
1064                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1065                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1066                                 cur_route.sort_by_key(|path| { path.hops.iter().map(|hop| hop.channel_fees.proportional_millionths as u64).sum::<u64>() });
1067                                 let expensive_payment_path = cur_route.first_mut().unwrap();
1068                                 // We already dropped all the small channels above, meaning all the
1069                                 // remaining channels are larger than remaining overpaid_value_msat.
1070                                 // Thus, this can't be negative.
1071                                 let expensive_path_new_value_msat = expensive_payment_path.get_value_msat() - overpaid_value_msat;
1072                                 expensive_payment_path.update_value_and_recompute_fees(expensive_path_new_value_msat);
1073                                 break;
1074                         }
1075                 }
1076                 drawn_routes.push(cur_route);
1077         }
1078
1079         // Step (8).
1080         // Select the best route by lowest total fee.
1081         drawn_routes.sort_by_key(|paths| paths.iter().map(|path| path.get_total_fee_paid_msat()).sum::<u64>());
1082         let mut selected_paths = Vec::<Vec<RouteHop>>::new();
1083         for payment_path in drawn_routes.first().unwrap() {
1084                 selected_paths.push(payment_path.hops.iter().map(|payment_hop| payment_hop.route_hop.clone()).collect());
1085         }
1086
1087         if let Some(features) = &payee_features {
1088                 for path in selected_paths.iter_mut() {
1089                         path.last_mut().unwrap().node_features = features.to_context();
1090                 }
1091         }
1092
1093         let route = Route { paths: selected_paths };
1094         log_trace!(logger, "Got route: {}", log_route!(route));
1095         Ok(route)
1096 }
1097
1098 #[cfg(test)]
1099 mod tests {
1100         use routing::router::{get_route, RouteHint, RoutingFees};
1101         use routing::network_graph::{NetworkGraph, NetGraphMsgHandler};
1102         use ln::features::{ChannelFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
1103         use ln::msgs::{ErrorAction, LightningError, OptionalField, UnsignedChannelAnnouncement, ChannelAnnouncement, RoutingMessageHandler,
1104            NodeAnnouncement, UnsignedNodeAnnouncement, ChannelUpdate, UnsignedChannelUpdate};
1105         use ln::channelmanager;
1106         use util::test_utils;
1107         use util::ser::Writeable;
1108
1109         use bitcoin::hashes::sha256d::Hash as Sha256dHash;
1110         use bitcoin::hashes::Hash;
1111         use bitcoin::network::constants::Network;
1112         use bitcoin::blockdata::constants::genesis_block;
1113         use bitcoin::blockdata::script::Builder;
1114         use bitcoin::blockdata::opcodes;
1115         use bitcoin::blockdata::transaction::TxOut;
1116
1117         use hex;
1118
1119         use bitcoin::secp256k1::key::{PublicKey,SecretKey};
1120         use bitcoin::secp256k1::{Secp256k1, All};
1121
1122         use std::sync::Arc;
1123
1124         // Using the same keys for LN and BTC ids
1125         fn add_channel(net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>, secp_ctx: &Secp256k1<All>, node_1_privkey: &SecretKey,
1126            node_2_privkey: &SecretKey, features: ChannelFeatures, short_channel_id: u64) {
1127                 let node_id_1 = PublicKey::from_secret_key(&secp_ctx, node_1_privkey);
1128                 let node_id_2 = PublicKey::from_secret_key(&secp_ctx, node_2_privkey);
1129
1130                 let unsigned_announcement = UnsignedChannelAnnouncement {
1131                         features,
1132                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1133                         short_channel_id,
1134                         node_id_1,
1135                         node_id_2,
1136                         bitcoin_key_1: node_id_1,
1137                         bitcoin_key_2: node_id_2,
1138                         excess_data: Vec::new(),
1139                 };
1140
1141                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1142                 let valid_announcement = ChannelAnnouncement {
1143                         node_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1144                         node_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1145                         bitcoin_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1146                         bitcoin_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1147                         contents: unsigned_announcement.clone(),
1148                 };
1149                 match net_graph_msg_handler.handle_channel_announcement(&valid_announcement) {
1150                         Ok(res) => assert!(res),
1151                         _ => panic!()
1152                 };
1153         }
1154
1155         fn update_channel(net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>, secp_ctx: &Secp256k1<All>, node_privkey: &SecretKey, update: UnsignedChannelUpdate) {
1156                 let msghash = hash_to_message!(&Sha256dHash::hash(&update.encode()[..])[..]);
1157                 let valid_channel_update = ChannelUpdate {
1158                         signature: secp_ctx.sign(&msghash, node_privkey),
1159                         contents: update.clone()
1160                 };
1161
1162                 match net_graph_msg_handler.handle_channel_update(&valid_channel_update) {
1163                         Ok(res) => assert!(res),
1164                         Err(_) => panic!()
1165                 };
1166         }
1167
1168         fn add_or_update_node(net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>, secp_ctx: &Secp256k1<All>, node_privkey: &SecretKey,
1169            features: NodeFeatures, timestamp: u32) {
1170                 let node_id = PublicKey::from_secret_key(&secp_ctx, node_privkey);
1171                 let unsigned_announcement = UnsignedNodeAnnouncement {
1172                         features,
1173                         timestamp,
1174                         node_id,
1175                         rgb: [0; 3],
1176                         alias: [0; 32],
1177                         addresses: Vec::new(),
1178                         excess_address_data: Vec::new(),
1179                         excess_data: Vec::new(),
1180                 };
1181                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1182                 let valid_announcement = NodeAnnouncement {
1183                         signature: secp_ctx.sign(&msghash, node_privkey),
1184                         contents: unsigned_announcement.clone()
1185                 };
1186
1187                 match net_graph_msg_handler.handle_node_announcement(&valid_announcement) {
1188                         Ok(_) => (),
1189                         Err(_) => panic!()
1190                 };
1191         }
1192
1193         fn get_nodes(secp_ctx: &Secp256k1<All>) -> (SecretKey, PublicKey, Vec<SecretKey>, Vec<PublicKey>) {
1194                 let privkeys: Vec<SecretKey> = (2..10).map(|i| {
1195                         SecretKey::from_slice(&hex::decode(format!("{:02}", i).repeat(32)).unwrap()[..]).unwrap()
1196                 }).collect();
1197
1198                 let pubkeys = privkeys.iter().map(|secret| PublicKey::from_secret_key(&secp_ctx, secret)).collect();
1199
1200                 let our_privkey = SecretKey::from_slice(&hex::decode("01".repeat(32)).unwrap()[..]).unwrap();
1201                 let our_id = PublicKey::from_secret_key(&secp_ctx, &our_privkey);
1202
1203                 (our_privkey, our_id, privkeys, pubkeys)
1204         }
1205
1206         fn id_to_feature_flags(id: u8) -> Vec<u8> {
1207                 // Set the feature flags to the id'th odd (ie non-required) feature bit so that we can
1208                 // test for it later.
1209                 let idx = (id - 1) * 2 + 1;
1210                 if idx > 8*3 {
1211                         vec![1 << (idx - 8*3), 0, 0, 0]
1212                 } else if idx > 8*2 {
1213                         vec![1 << (idx - 8*2), 0, 0]
1214                 } else if idx > 8*1 {
1215                         vec![1 << (idx - 8*1), 0]
1216                 } else {
1217                         vec![1 << idx]
1218                 }
1219         }
1220
1221         fn build_graph() -> (Secp256k1<All>, NetGraphMsgHandler<std::sync::Arc<test_utils::TestChainSource>, std::sync::Arc<crate::util::test_utils::TestLogger>>, std::sync::Arc<test_utils::TestChainSource>, std::sync::Arc<test_utils::TestLogger>) {
1222                 let secp_ctx = Secp256k1::new();
1223                 let logger = Arc::new(test_utils::TestLogger::new());
1224                 let chain_monitor = Arc::new(test_utils::TestChainSource::new(Network::Testnet));
1225                 let net_graph_msg_handler = NetGraphMsgHandler::new(genesis_block(Network::Testnet).header.block_hash(), None, Arc::clone(&logger));
1226                 // Build network from our_id to node7:
1227                 //
1228                 //        -1(1)2-  node0  -1(3)2-
1229                 //       /                       \
1230                 // our_id -1(12)2- node7 -1(13)2--- node2
1231                 //       \                       /
1232                 //        -1(2)2-  node1  -1(4)2-
1233                 //
1234                 //
1235                 // chan1  1-to-2: disabled
1236                 // chan1  2-to-1: enabled, 0 fee
1237                 //
1238                 // chan2  1-to-2: enabled, ignored fee
1239                 // chan2  2-to-1: enabled, 0 fee
1240                 //
1241                 // chan3  1-to-2: enabled, 0 fee
1242                 // chan3  2-to-1: enabled, 100 msat fee
1243                 //
1244                 // chan4  1-to-2: enabled, 100% fee
1245                 // chan4  2-to-1: enabled, 0 fee
1246                 //
1247                 // chan12 1-to-2: enabled, ignored fee
1248                 // chan12 2-to-1: enabled, 0 fee
1249                 //
1250                 // chan13 1-to-2: enabled, 200% fee
1251                 // chan13 2-to-1: enabled, 0 fee
1252                 //
1253                 //
1254                 //       -1(5)2- node3 -1(8)2--
1255                 //       |         2          |
1256                 //       |       (11)         |
1257                 //      /          1           \
1258                 // node2--1(6)2- node4 -1(9)2--- node6 (not in global route map)
1259                 //      \                      /
1260                 //       -1(7)2- node5 -1(10)2-
1261                 //
1262                 // chan5  1-to-2: enabled, 100 msat fee
1263                 // chan5  2-to-1: enabled, 0 fee
1264                 //
1265                 // chan6  1-to-2: enabled, 0 fee
1266                 // chan6  2-to-1: enabled, 0 fee
1267                 //
1268                 // chan7  1-to-2: enabled, 100% fee
1269                 // chan7  2-to-1: enabled, 0 fee
1270                 //
1271                 // chan8  1-to-2: enabled, variable fee (0 then 1000 msat)
1272                 // chan8  2-to-1: enabled, 0 fee
1273                 //
1274                 // chan9  1-to-2: enabled, 1001 msat fee
1275                 // chan9  2-to-1: enabled, 0 fee
1276                 //
1277                 // chan10 1-to-2: enabled, 0 fee
1278                 // chan10 2-to-1: enabled, 0 fee
1279                 //
1280                 // chan11 1-to-2: enabled, 0 fee
1281                 // chan11 2-to-1: enabled, 0 fee
1282
1283                 let (our_privkey, _, privkeys, _) = get_nodes(&secp_ctx);
1284
1285                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[0], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
1286                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1287                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1288                         short_channel_id: 1,
1289                         timestamp: 1,
1290                         flags: 1,
1291                         cltv_expiry_delta: 0,
1292                         htlc_minimum_msat: 0,
1293                         htlc_maximum_msat: OptionalField::Absent,
1294                         fee_base_msat: 0,
1295                         fee_proportional_millionths: 0,
1296                         excess_data: Vec::new()
1297                 });
1298
1299                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
1300
1301                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
1302                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1303                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1304                         short_channel_id: 2,
1305                         timestamp: 1,
1306                         flags: 0,
1307                         cltv_expiry_delta: u16::max_value(),
1308                         htlc_minimum_msat: 0,
1309                         htlc_maximum_msat: OptionalField::Absent,
1310                         fee_base_msat: u32::max_value(),
1311                         fee_proportional_millionths: u32::max_value(),
1312                         excess_data: Vec::new()
1313                 });
1314                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1315                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1316                         short_channel_id: 2,
1317                         timestamp: 1,
1318                         flags: 1,
1319                         cltv_expiry_delta: 0,
1320                         htlc_minimum_msat: 0,
1321                         htlc_maximum_msat: OptionalField::Absent,
1322                         fee_base_msat: 0,
1323                         fee_proportional_millionths: 0,
1324                         excess_data: Vec::new()
1325                 });
1326
1327                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
1328
1329                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[7], ChannelFeatures::from_le_bytes(id_to_feature_flags(12)), 12);
1330                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1331                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1332                         short_channel_id: 12,
1333                         timestamp: 1,
1334                         flags: 0,
1335                         cltv_expiry_delta: u16::max_value(),
1336                         htlc_minimum_msat: 0,
1337                         htlc_maximum_msat: OptionalField::Absent,
1338                         fee_base_msat: u32::max_value(),
1339                         fee_proportional_millionths: u32::max_value(),
1340                         excess_data: Vec::new()
1341                 });
1342                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1343                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1344                         short_channel_id: 12,
1345                         timestamp: 1,
1346                         flags: 1,
1347                         cltv_expiry_delta: 0,
1348                         htlc_minimum_msat: 0,
1349                         htlc_maximum_msat: OptionalField::Absent,
1350                         fee_base_msat: 0,
1351                         fee_proportional_millionths: 0,
1352                         excess_data: Vec::new()
1353                 });
1354
1355                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], NodeFeatures::from_le_bytes(id_to_feature_flags(8)), 0);
1356
1357                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
1358                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1359                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1360                         short_channel_id: 3,
1361                         timestamp: 1,
1362                         flags: 0,
1363                         cltv_expiry_delta: (3 << 8) | 1,
1364                         htlc_minimum_msat: 0,
1365                         htlc_maximum_msat: OptionalField::Absent,
1366                         fee_base_msat: 0,
1367                         fee_proportional_millionths: 0,
1368                         excess_data: Vec::new()
1369                 });
1370                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1371                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1372                         short_channel_id: 3,
1373                         timestamp: 1,
1374                         flags: 1,
1375                         cltv_expiry_delta: (3 << 8) | 2,
1376                         htlc_minimum_msat: 0,
1377                         htlc_maximum_msat: OptionalField::Absent,
1378                         fee_base_msat: 100,
1379                         fee_proportional_millionths: 0,
1380                         excess_data: Vec::new()
1381                 });
1382
1383                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
1384                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1385                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1386                         short_channel_id: 4,
1387                         timestamp: 1,
1388                         flags: 0,
1389                         cltv_expiry_delta: (4 << 8) | 1,
1390                         htlc_minimum_msat: 0,
1391                         htlc_maximum_msat: OptionalField::Absent,
1392                         fee_base_msat: 0,
1393                         fee_proportional_millionths: 1000000,
1394                         excess_data: Vec::new()
1395                 });
1396                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1397                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1398                         short_channel_id: 4,
1399                         timestamp: 1,
1400                         flags: 1,
1401                         cltv_expiry_delta: (4 << 8) | 2,
1402                         htlc_minimum_msat: 0,
1403                         htlc_maximum_msat: OptionalField::Absent,
1404                         fee_base_msat: 0,
1405                         fee_proportional_millionths: 0,
1406                         excess_data: Vec::new()
1407                 });
1408
1409                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(13)), 13);
1410                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1411                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1412                         short_channel_id: 13,
1413                         timestamp: 1,
1414                         flags: 0,
1415                         cltv_expiry_delta: (13 << 8) | 1,
1416                         htlc_minimum_msat: 0,
1417                         htlc_maximum_msat: OptionalField::Absent,
1418                         fee_base_msat: 0,
1419                         fee_proportional_millionths: 2000000,
1420                         excess_data: Vec::new()
1421                 });
1422                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1423                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1424                         short_channel_id: 13,
1425                         timestamp: 1,
1426                         flags: 1,
1427                         cltv_expiry_delta: (13 << 8) | 2,
1428                         htlc_minimum_msat: 0,
1429                         htlc_maximum_msat: OptionalField::Absent,
1430                         fee_base_msat: 0,
1431                         fee_proportional_millionths: 0,
1432                         excess_data: Vec::new()
1433                 });
1434
1435                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
1436
1437                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
1438                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1439                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1440                         short_channel_id: 6,
1441                         timestamp: 1,
1442                         flags: 0,
1443                         cltv_expiry_delta: (6 << 8) | 1,
1444                         htlc_minimum_msat: 0,
1445                         htlc_maximum_msat: OptionalField::Absent,
1446                         fee_base_msat: 0,
1447                         fee_proportional_millionths: 0,
1448                         excess_data: Vec::new()
1449                 });
1450                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1451                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1452                         short_channel_id: 6,
1453                         timestamp: 1,
1454                         flags: 1,
1455                         cltv_expiry_delta: (6 << 8) | 2,
1456                         htlc_minimum_msat: 0,
1457                         htlc_maximum_msat: OptionalField::Absent,
1458                         fee_base_msat: 0,
1459                         fee_proportional_millionths: 0,
1460                         excess_data: Vec::new(),
1461                 });
1462
1463                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(11)), 11);
1464                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1465                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1466                         short_channel_id: 11,
1467                         timestamp: 1,
1468                         flags: 0,
1469                         cltv_expiry_delta: (11 << 8) | 1,
1470                         htlc_minimum_msat: 0,
1471                         htlc_maximum_msat: OptionalField::Absent,
1472                         fee_base_msat: 0,
1473                         fee_proportional_millionths: 0,
1474                         excess_data: Vec::new()
1475                 });
1476                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
1477                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1478                         short_channel_id: 11,
1479                         timestamp: 1,
1480                         flags: 1,
1481                         cltv_expiry_delta: (11 << 8) | 2,
1482                         htlc_minimum_msat: 0,
1483                         htlc_maximum_msat: OptionalField::Absent,
1484                         fee_base_msat: 0,
1485                         fee_proportional_millionths: 0,
1486                         excess_data: Vec::new()
1487                 });
1488
1489                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(5)), 0);
1490
1491                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
1492
1493                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[5], ChannelFeatures::from_le_bytes(id_to_feature_flags(7)), 7);
1494                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1495                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1496                         short_channel_id: 7,
1497                         timestamp: 1,
1498                         flags: 0,
1499                         cltv_expiry_delta: (7 << 8) | 1,
1500                         htlc_minimum_msat: 0,
1501                         htlc_maximum_msat: OptionalField::Absent,
1502                         fee_base_msat: 0,
1503                         fee_proportional_millionths: 1000000,
1504                         excess_data: Vec::new()
1505                 });
1506                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[5], UnsignedChannelUpdate {
1507                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1508                         short_channel_id: 7,
1509                         timestamp: 1,
1510                         flags: 1,
1511                         cltv_expiry_delta: (7 << 8) | 2,
1512                         htlc_minimum_msat: 0,
1513                         htlc_maximum_msat: OptionalField::Absent,
1514                         fee_base_msat: 0,
1515                         fee_proportional_millionths: 0,
1516                         excess_data: Vec::new()
1517                 });
1518
1519                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[5], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
1520
1521                 (secp_ctx, net_graph_msg_handler, chain_monitor, logger)
1522         }
1523
1524         #[test]
1525         fn simple_route_test() {
1526                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1527                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1528
1529                 // Simple route to 2 via 1
1530
1531                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 0, 42, Arc::clone(&logger)) {
1532                         assert_eq!(err, "Cannot send a payment of 0 msat");
1533                 } else { panic!(); }
1534
1535                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
1536                 assert_eq!(route.paths[0].len(), 2);
1537
1538                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
1539                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1540                 assert_eq!(route.paths[0][0].fee_msat, 100);
1541                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
1542                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
1543                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
1544
1545                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1546                 assert_eq!(route.paths[0][1].short_channel_id, 4);
1547                 assert_eq!(route.paths[0][1].fee_msat, 100);
1548                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1549                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1550                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
1551         }
1552
1553         #[test]
1554         fn invalid_first_hop_test() {
1555                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1556                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1557
1558                 // Simple route to 2 via 1
1559
1560                 let our_chans = vec![channelmanager::ChannelDetails {
1561                         channel_id: [0; 32],
1562                         short_channel_id: Some(2),
1563                         remote_network_id: our_id,
1564                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1565                         channel_value_satoshis: 100000,
1566                         user_id: 0,
1567                         outbound_capacity_msat: 100000,
1568                         inbound_capacity_msat: 100000,
1569                         is_live: true,
1570                         counterparty_forwarding_info: None,
1571                 }];
1572
1573                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger)) {
1574                         assert_eq!(err, "First hop cannot have our_node_id as a destination.");
1575                 } else { panic!(); }
1576
1577                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
1578                 assert_eq!(route.paths[0].len(), 2);
1579         }
1580
1581         #[test]
1582         fn htlc_minimum_test() {
1583                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1584                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1585
1586                 // Simple route to 2 via 1
1587
1588                 // Disable other paths
1589                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1590                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1591                         short_channel_id: 12,
1592                         timestamp: 2,
1593                         flags: 2, // to disable
1594                         cltv_expiry_delta: 0,
1595                         htlc_minimum_msat: 0,
1596                         htlc_maximum_msat: OptionalField::Absent,
1597                         fee_base_msat: 0,
1598                         fee_proportional_millionths: 0,
1599                         excess_data: Vec::new()
1600                 });
1601                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1602                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1603                         short_channel_id: 3,
1604                         timestamp: 2,
1605                         flags: 2, // to disable
1606                         cltv_expiry_delta: 0,
1607                         htlc_minimum_msat: 0,
1608                         htlc_maximum_msat: OptionalField::Absent,
1609                         fee_base_msat: 0,
1610                         fee_proportional_millionths: 0,
1611                         excess_data: Vec::new()
1612                 });
1613                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1614                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1615                         short_channel_id: 13,
1616                         timestamp: 2,
1617                         flags: 2, // to disable
1618                         cltv_expiry_delta: 0,
1619                         htlc_minimum_msat: 0,
1620                         htlc_maximum_msat: OptionalField::Absent,
1621                         fee_base_msat: 0,
1622                         fee_proportional_millionths: 0,
1623                         excess_data: Vec::new()
1624                 });
1625                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1626                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1627                         short_channel_id: 6,
1628                         timestamp: 2,
1629                         flags: 2, // to disable
1630                         cltv_expiry_delta: 0,
1631                         htlc_minimum_msat: 0,
1632                         htlc_maximum_msat: OptionalField::Absent,
1633                         fee_base_msat: 0,
1634                         fee_proportional_millionths: 0,
1635                         excess_data: Vec::new()
1636                 });
1637                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1638                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1639                         short_channel_id: 7,
1640                         timestamp: 2,
1641                         flags: 2, // to disable
1642                         cltv_expiry_delta: 0,
1643                         htlc_minimum_msat: 0,
1644                         htlc_maximum_msat: OptionalField::Absent,
1645                         fee_base_msat: 0,
1646                         fee_proportional_millionths: 0,
1647                         excess_data: Vec::new()
1648                 });
1649
1650                 // Check against amount_to_transfer_over_msat.
1651                 // Set minimal HTLC of 200_000_000 msat.
1652                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1653                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1654                         short_channel_id: 2,
1655                         timestamp: 3,
1656                         flags: 0,
1657                         cltv_expiry_delta: 0,
1658                         htlc_minimum_msat: 200_000_000,
1659                         htlc_maximum_msat: OptionalField::Absent,
1660                         fee_base_msat: 0,
1661                         fee_proportional_millionths: 0,
1662                         excess_data: Vec::new()
1663                 });
1664
1665                 // Second hop only allows to forward 199_999_999 at most, thus not allowing the first hop to
1666                 // be used.
1667                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1668                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1669                         short_channel_id: 4,
1670                         timestamp: 3,
1671                         flags: 0,
1672                         cltv_expiry_delta: 0,
1673                         htlc_minimum_msat: 0,
1674                         htlc_maximum_msat: OptionalField::Present(199_999_999),
1675                         fee_base_msat: 0,
1676                         fee_proportional_millionths: 0,
1677                         excess_data: Vec::new()
1678                 });
1679
1680                 // Not possible to send 199_999_999, because the minimum on channel=2 is 200_000_000.
1681                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 199_999_999, 42, Arc::clone(&logger)) {
1682                         assert_eq!(err, "Failed to find a path to the given destination");
1683                 } else { panic!(); }
1684
1685                 // Lift the restriction on the first hop.
1686                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1687                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1688                         short_channel_id: 2,
1689                         timestamp: 4,
1690                         flags: 0,
1691                         cltv_expiry_delta: 0,
1692                         htlc_minimum_msat: 0,
1693                         htlc_maximum_msat: OptionalField::Absent,
1694                         fee_base_msat: 0,
1695                         fee_proportional_millionths: 0,
1696                         excess_data: Vec::new()
1697                 });
1698
1699                 // A payment above the minimum should pass
1700                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 199_999_999, 42, Arc::clone(&logger)).unwrap();
1701                 assert_eq!(route.paths[0].len(), 2);
1702         }
1703
1704         #[test]
1705         fn htlc_minimum_overpay_test() {
1706                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1707                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1708
1709                 // A route to node#2 via two paths.
1710                 // One path allows transferring 35-40 sats, another one also allows 35-40 sats.
1711                 // Thus, they can't send 60 without overpaying.
1712                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1713                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1714                         short_channel_id: 2,
1715                         timestamp: 2,
1716                         flags: 0,
1717                         cltv_expiry_delta: 0,
1718                         htlc_minimum_msat: 35_000,
1719                         htlc_maximum_msat: OptionalField::Present(40_000),
1720                         fee_base_msat: 0,
1721                         fee_proportional_millionths: 0,
1722                         excess_data: Vec::new()
1723                 });
1724                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1725                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1726                         short_channel_id: 12,
1727                         timestamp: 3,
1728                         flags: 0,
1729                         cltv_expiry_delta: 0,
1730                         htlc_minimum_msat: 35_000,
1731                         htlc_maximum_msat: OptionalField::Present(40_000),
1732                         fee_base_msat: 0,
1733                         fee_proportional_millionths: 0,
1734                         excess_data: Vec::new()
1735                 });
1736
1737                 // Make 0 fee.
1738                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1739                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1740                         short_channel_id: 13,
1741                         timestamp: 2,
1742                         flags: 0,
1743                         cltv_expiry_delta: 0,
1744                         htlc_minimum_msat: 0,
1745                         htlc_maximum_msat: OptionalField::Absent,
1746                         fee_base_msat: 0,
1747                         fee_proportional_millionths: 0,
1748                         excess_data: Vec::new()
1749                 });
1750                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1751                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1752                         short_channel_id: 4,
1753                         timestamp: 2,
1754                         flags: 0,
1755                         cltv_expiry_delta: 0,
1756                         htlc_minimum_msat: 0,
1757                         htlc_maximum_msat: OptionalField::Absent,
1758                         fee_base_msat: 0,
1759                         fee_proportional_millionths: 0,
1760                         excess_data: Vec::new()
1761                 });
1762
1763                 // Disable other paths
1764                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1765                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1766                         short_channel_id: 1,
1767                         timestamp: 3,
1768                         flags: 2, // to disable
1769                         cltv_expiry_delta: 0,
1770                         htlc_minimum_msat: 0,
1771                         htlc_maximum_msat: OptionalField::Absent,
1772                         fee_base_msat: 0,
1773                         fee_proportional_millionths: 0,
1774                         excess_data: Vec::new()
1775                 });
1776
1777                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1778                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)).unwrap();
1779                 // Overpay fees to hit htlc_minimum_msat.
1780                 let overpaid_fees = route.paths[0][0].fee_msat + route.paths[1][0].fee_msat;
1781                 // TODO: this could be better balanced to overpay 10k and not 15k.
1782                 assert_eq!(overpaid_fees, 15_000);
1783
1784                 // Now, test that if there are 2 paths, a "cheaper" by fee path wouldn't be prioritized
1785                 // while taking even more fee to match htlc_minimum_msat.
1786                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1787                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1788                         short_channel_id: 12,
1789                         timestamp: 4,
1790                         flags: 0,
1791                         cltv_expiry_delta: 0,
1792                         htlc_minimum_msat: 65_000,
1793                         htlc_maximum_msat: OptionalField::Present(80_000),
1794                         fee_base_msat: 0,
1795                         fee_proportional_millionths: 0,
1796                         excess_data: Vec::new()
1797                 });
1798                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1799                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1800                         short_channel_id: 2,
1801                         timestamp: 3,
1802                         flags: 0,
1803                         cltv_expiry_delta: 0,
1804                         htlc_minimum_msat: 0,
1805                         htlc_maximum_msat: OptionalField::Absent,
1806                         fee_base_msat: 0,
1807                         fee_proportional_millionths: 0,
1808                         excess_data: Vec::new()
1809                 });
1810                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1811                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1812                         short_channel_id: 4,
1813                         timestamp: 4,
1814                         flags: 0,
1815                         cltv_expiry_delta: 0,
1816                         htlc_minimum_msat: 0,
1817                         htlc_maximum_msat: OptionalField::Absent,
1818                         fee_base_msat: 0,
1819                         fee_proportional_millionths: 100_000,
1820                         excess_data: Vec::new()
1821                 });
1822
1823                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1824                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)).unwrap();
1825                 // Fine to overpay for htlc_minimum_msat if it allows us to save fee.
1826                 assert_eq!(route.paths.len(), 1);
1827                 assert_eq!(route.paths[0][0].short_channel_id, 12);
1828                 let fees = route.paths[0][0].fee_msat;
1829                 assert_eq!(fees, 5_000);
1830
1831                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1832                         Some(InvoiceFeatures::known()), None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
1833                 // Not fine to overpay for htlc_minimum_msat if it requires paying more than fee on
1834                 // the other channel.
1835                 assert_eq!(route.paths.len(), 1);
1836                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1837                 let fees = route.paths[0][0].fee_msat;
1838                 assert_eq!(fees, 5_000);
1839         }
1840
1841         #[test]
1842         fn disable_channels_test() {
1843                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1844                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1845
1846                 // // Disable channels 4 and 12 by flags=2
1847                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1848                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1849                         short_channel_id: 4,
1850                         timestamp: 2,
1851                         flags: 2, // to disable
1852                         cltv_expiry_delta: 0,
1853                         htlc_minimum_msat: 0,
1854                         htlc_maximum_msat: OptionalField::Absent,
1855                         fee_base_msat: 0,
1856                         fee_proportional_millionths: 0,
1857                         excess_data: Vec::new()
1858                 });
1859                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1860                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1861                         short_channel_id: 12,
1862                         timestamp: 2,
1863                         flags: 2, // to disable
1864                         cltv_expiry_delta: 0,
1865                         htlc_minimum_msat: 0,
1866                         htlc_maximum_msat: OptionalField::Absent,
1867                         fee_base_msat: 0,
1868                         fee_proportional_millionths: 0,
1869                         excess_data: Vec::new()
1870                 });
1871
1872                 // If all the channels require some features we don't understand, route should fail
1873                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)) {
1874                         assert_eq!(err, "Failed to find a path to the given destination");
1875                 } else { panic!(); }
1876
1877                 // If we specify a channel to node7, that overrides our local channel view and that gets used
1878                 let our_chans = vec![channelmanager::ChannelDetails {
1879                         channel_id: [0; 32],
1880                         short_channel_id: Some(42),
1881                         remote_network_id: nodes[7].clone(),
1882                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1883                         channel_value_satoshis: 0,
1884                         user_id: 0,
1885                         outbound_capacity_msat: 250_000_000,
1886                         inbound_capacity_msat: 0,
1887                         is_live: true,
1888                         counterparty_forwarding_info: None,
1889                 }];
1890                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()),  &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
1891                 assert_eq!(route.paths[0].len(), 2);
1892
1893                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
1894                 assert_eq!(route.paths[0][0].short_channel_id, 42);
1895                 assert_eq!(route.paths[0][0].fee_msat, 200);
1896                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
1897                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
1898                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
1899
1900                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1901                 assert_eq!(route.paths[0][1].short_channel_id, 13);
1902                 assert_eq!(route.paths[0][1].fee_msat, 100);
1903                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1904                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1905                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
1906         }
1907
1908         #[test]
1909         fn disable_node_test() {
1910                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1911                 let (_, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1912
1913                 // Disable nodes 1, 2, and 8 by requiring unknown feature bits
1914                 let mut unknown_features = NodeFeatures::known();
1915                 unknown_features.set_required_unknown_bits();
1916                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], unknown_features.clone(), 1);
1917                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], unknown_features.clone(), 1);
1918                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], unknown_features.clone(), 1);
1919
1920                 // If all nodes require some features we don't understand, route should fail
1921                 if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)) {
1922                         assert_eq!(err, "Failed to find a path to the given destination");
1923                 } else { panic!(); }
1924
1925                 // If we specify a channel to node7, that overrides our local channel view and that gets used
1926                 let our_chans = vec![channelmanager::ChannelDetails {
1927                         channel_id: [0; 32],
1928                         short_channel_id: Some(42),
1929                         remote_network_id: nodes[7].clone(),
1930                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1931                         channel_value_satoshis: 0,
1932                         user_id: 0,
1933                         outbound_capacity_msat: 250_000_000,
1934                         inbound_capacity_msat: 0,
1935                         is_live: true,
1936                         counterparty_forwarding_info: None,
1937                 }];
1938                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
1939                 assert_eq!(route.paths[0].len(), 2);
1940
1941                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
1942                 assert_eq!(route.paths[0][0].short_channel_id, 42);
1943                 assert_eq!(route.paths[0][0].fee_msat, 200);
1944                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
1945                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
1946                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
1947
1948                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1949                 assert_eq!(route.paths[0][1].short_channel_id, 13);
1950                 assert_eq!(route.paths[0][1].fee_msat, 100);
1951                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1952                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1953                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
1954
1955                 // Note that we don't test disabling node 3 and failing to route to it, as we (somewhat
1956                 // naively) assume that the user checked the feature bits on the invoice, which override
1957                 // the node_announcement.
1958         }
1959
1960         #[test]
1961         fn our_chans_test() {
1962                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1963                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1964
1965                 // Route to 1 via 2 and 3 because our channel to 1 is disabled
1966                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[0], None, None, &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
1967                 assert_eq!(route.paths[0].len(), 3);
1968
1969                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
1970                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1971                 assert_eq!(route.paths[0][0].fee_msat, 200);
1972                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
1973                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
1974                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
1975
1976                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1977                 assert_eq!(route.paths[0][1].short_channel_id, 4);
1978                 assert_eq!(route.paths[0][1].fee_msat, 100);
1979                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (3 << 8) | 2);
1980                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1981                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
1982
1983                 assert_eq!(route.paths[0][2].pubkey, nodes[0]);
1984                 assert_eq!(route.paths[0][2].short_channel_id, 3);
1985                 assert_eq!(route.paths[0][2].fee_msat, 100);
1986                 assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
1987                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(1));
1988                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(3));
1989
1990                 // If we specify a channel to node7, that overrides our local channel view and that gets used
1991                 let our_chans = vec![channelmanager::ChannelDetails {
1992                         channel_id: [0; 32],
1993                         short_channel_id: Some(42),
1994                         remote_network_id: nodes[7].clone(),
1995                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1996                         channel_value_satoshis: 0,
1997                         user_id: 0,
1998                         outbound_capacity_msat: 250_000_000,
1999                         inbound_capacity_msat: 0,
2000                         is_live: true,
2001                         counterparty_forwarding_info: None,
2002                 }];
2003                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 100, 42, Arc::clone(&logger)).unwrap();
2004                 assert_eq!(route.paths[0].len(), 2);
2005
2006                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2007                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2008                 assert_eq!(route.paths[0][0].fee_msat, 200);
2009                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2010                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2011                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2012
2013                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2014                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2015                 assert_eq!(route.paths[0][1].fee_msat, 100);
2016                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2017                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2018                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2019         }
2020
2021         fn last_hops(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2022                 let zero_fees = RoutingFees {
2023                         base_msat: 0,
2024                         proportional_millionths: 0,
2025                 };
2026                 vec!(RouteHint {
2027                         src_node_id: nodes[3].clone(),
2028                         short_channel_id: 8,
2029                         fees: zero_fees,
2030                         cltv_expiry_delta: (8 << 8) | 1,
2031                         htlc_minimum_msat: None,
2032                         htlc_maximum_msat: None,
2033                 }, RouteHint {
2034                         src_node_id: nodes[4].clone(),
2035                         short_channel_id: 9,
2036                         fees: RoutingFees {
2037                                 base_msat: 1001,
2038                                 proportional_millionths: 0,
2039                         },
2040                         cltv_expiry_delta: (9 << 8) | 1,
2041                         htlc_minimum_msat: None,
2042                         htlc_maximum_msat: None,
2043                 }, RouteHint {
2044                         src_node_id: nodes[5].clone(),
2045                         short_channel_id: 10,
2046                         fees: zero_fees,
2047                         cltv_expiry_delta: (10 << 8) | 1,
2048                         htlc_minimum_msat: None,
2049                         htlc_maximum_msat: None,
2050                 })
2051         }
2052
2053         #[test]
2054         fn last_hops_test() {
2055                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2056                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2057
2058                 // Simple test across 2, 3, 5, and 4 via a last_hop channel
2059
2060                 // First check that lst hop can't have its source as the payee.
2061                 let invalid_last_hop = RouteHint {
2062                         src_node_id: nodes[6],
2063                         short_channel_id: 8,
2064                         fees: RoutingFees {
2065                                 base_msat: 1000,
2066                                 proportional_millionths: 0,
2067                         },
2068                         cltv_expiry_delta: (8 << 8) | 1,
2069                         htlc_minimum_msat: None,
2070                         htlc_maximum_msat: None,
2071                 };
2072
2073                 let mut invalid_last_hops = last_hops(&nodes);
2074                 invalid_last_hops.push(invalid_last_hop);
2075                 {
2076                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &invalid_last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)) {
2077                                 assert_eq!(err, "Last hop cannot have a payee as a source.");
2078                         } else { panic!(); }
2079                 }
2080
2081                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &last_hops(&nodes).iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2082                 assert_eq!(route.paths[0].len(), 5);
2083
2084                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2085                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2086                 assert_eq!(route.paths[0][0].fee_msat, 100);
2087                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2088                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2089                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2090
2091                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2092                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2093                 assert_eq!(route.paths[0][1].fee_msat, 0);
2094                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2095                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2096                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2097
2098                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2099                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2100                 assert_eq!(route.paths[0][2].fee_msat, 0);
2101                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2102                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2103                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2104
2105                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2106                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2107                 assert_eq!(route.paths[0][3].fee_msat, 0);
2108                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2109                 // If we have a peer in the node map, we'll use their features here since we don't have
2110                 // a way of figuring out their features from the invoice:
2111                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2112                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2113
2114                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2115                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2116                 assert_eq!(route.paths[0][4].fee_msat, 100);
2117                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2118                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2119                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2120         }
2121
2122         #[test]
2123         fn our_chans_last_hop_connect_test() {
2124                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2125                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2126
2127                 // Simple test with outbound channel to 4 to test that last_hops and first_hops connect
2128                 let our_chans = vec![channelmanager::ChannelDetails {
2129                         channel_id: [0; 32],
2130                         short_channel_id: Some(42),
2131                         remote_network_id: nodes[3].clone(),
2132                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2133                         channel_value_satoshis: 0,
2134                         user_id: 0,
2135                         outbound_capacity_msat: 250_000_000,
2136                         inbound_capacity_msat: 0,
2137                         is_live: true,
2138                         counterparty_forwarding_info: None,
2139                 }];
2140                 let mut last_hops = last_hops(&nodes);
2141                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, Some(&our_chans.iter().collect::<Vec<_>>()), &last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2142                 assert_eq!(route.paths[0].len(), 2);
2143
2144                 assert_eq!(route.paths[0][0].pubkey, nodes[3]);
2145                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2146                 assert_eq!(route.paths[0][0].fee_msat, 0);
2147                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2148                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2149                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2150
2151                 assert_eq!(route.paths[0][1].pubkey, nodes[6]);
2152                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2153                 assert_eq!(route.paths[0][1].fee_msat, 100);
2154                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2155                 assert_eq!(route.paths[0][1].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2156                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2157
2158                 last_hops[0].fees.base_msat = 1000;
2159
2160                 // Revert to via 6 as the fee on 8 goes up
2161                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::clone(&logger)).unwrap();
2162                 assert_eq!(route.paths[0].len(), 4);
2163
2164                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2165                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2166                 assert_eq!(route.paths[0][0].fee_msat, 200); // fee increased as its % of value transferred across node
2167                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2168                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2169                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2170
2171                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2172                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2173                 assert_eq!(route.paths[0][1].fee_msat, 100);
2174                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (7 << 8) | 1);
2175                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2176                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2177
2178                 assert_eq!(route.paths[0][2].pubkey, nodes[5]);
2179                 assert_eq!(route.paths[0][2].short_channel_id, 7);
2180                 assert_eq!(route.paths[0][2].fee_msat, 0);
2181                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (10 << 8) | 1);
2182                 // If we have a peer in the node map, we'll use their features here since we don't have
2183                 // a way of figuring out their features from the invoice:
2184                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
2185                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(7));
2186
2187                 assert_eq!(route.paths[0][3].pubkey, nodes[6]);
2188                 assert_eq!(route.paths[0][3].short_channel_id, 10);
2189                 assert_eq!(route.paths[0][3].fee_msat, 100);
2190                 assert_eq!(route.paths[0][3].cltv_expiry_delta, 42);
2191                 assert_eq!(route.paths[0][3].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2192                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2193
2194                 // ...but still use 8 for larger payments as 6 has a variable feerate
2195                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &last_hops.iter().collect::<Vec<_>>(), 2000, 42, Arc::clone(&logger)).unwrap();
2196                 assert_eq!(route.paths[0].len(), 5);
2197
2198                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2199                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2200                 assert_eq!(route.paths[0][0].fee_msat, 3000);
2201                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2202                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2203                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2204
2205                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2206                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2207                 assert_eq!(route.paths[0][1].fee_msat, 0);
2208                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2209                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2210                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2211
2212                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2213                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2214                 assert_eq!(route.paths[0][2].fee_msat, 0);
2215                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2216                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2217                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2218
2219                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2220                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2221                 assert_eq!(route.paths[0][3].fee_msat, 1000);
2222                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2223                 // If we have a peer in the node map, we'll use their features here since we don't have
2224                 // a way of figuring out their features from the invoice:
2225                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2226                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2227
2228                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2229                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2230                 assert_eq!(route.paths[0][4].fee_msat, 2000);
2231                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2232                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2233                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2234         }
2235
2236         #[test]
2237         fn unannounced_path_test() {
2238                 // We should be able to send a payment to a destination without any help of a routing graph
2239                 // if we have a channel with a common counterparty that appears in the first and last hop
2240                 // hints.
2241                 let source_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 41).repeat(32)).unwrap()[..]).unwrap());
2242                 let middle_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 42).repeat(32)).unwrap()[..]).unwrap());
2243                 let target_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 43).repeat(32)).unwrap()[..]).unwrap());
2244
2245                 // If we specify a channel to a middle hop, that overrides our local channel view and that gets used
2246                 let last_hops = vec![RouteHint {
2247                         src_node_id: middle_node_id,
2248                         short_channel_id: 8,
2249                         fees: RoutingFees {
2250                                 base_msat: 1000,
2251                                 proportional_millionths: 0,
2252                         },
2253                         cltv_expiry_delta: (8 << 8) | 1,
2254                         htlc_minimum_msat: None,
2255                         htlc_maximum_msat: None,
2256                 }];
2257                 let our_chans = vec![channelmanager::ChannelDetails {
2258                         channel_id: [0; 32],
2259                         short_channel_id: Some(42),
2260                         remote_network_id: middle_node_id,
2261                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2262                         channel_value_satoshis: 100000,
2263                         user_id: 0,
2264                         outbound_capacity_msat: 100000,
2265                         inbound_capacity_msat: 100000,
2266                         is_live: true,
2267                         counterparty_forwarding_info: None,
2268                 }];
2269                 let route = get_route(&source_node_id, &NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash()), &target_node_id, None, Some(&our_chans.iter().collect::<Vec<_>>()), &last_hops.iter().collect::<Vec<_>>(), 100, 42, Arc::new(test_utils::TestLogger::new())).unwrap();
2270
2271                 assert_eq!(route.paths[0].len(), 2);
2272
2273                 assert_eq!(route.paths[0][0].pubkey, middle_node_id);
2274                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2275                 assert_eq!(route.paths[0][0].fee_msat, 1000);
2276                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2277                 assert_eq!(route.paths[0][0].node_features.le_flags(), &[0b11]);
2278                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2279
2280                 assert_eq!(route.paths[0][1].pubkey, target_node_id);
2281                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2282                 assert_eq!(route.paths[0][1].fee_msat, 100);
2283                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2284                 assert_eq!(route.paths[0][1].node_features.le_flags(), &[0; 0]); // We dont pass flags in from invoices yet
2285                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2286         }
2287
2288         #[test]
2289         fn available_amount_while_routing_test() {
2290                 // Tests whether we choose the correct available channel amount while routing.
2291
2292                 let (secp_ctx, mut net_graph_msg_handler, chain_monitor, logger) = build_graph();
2293                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2294
2295                 // We will use a simple single-path route from
2296                 // our node to node2 via node0: channels {1, 3}.
2297
2298                 // First disable all other paths.
2299                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2300                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2301                         short_channel_id: 2,
2302                         timestamp: 2,
2303                         flags: 2,
2304                         cltv_expiry_delta: 0,
2305                         htlc_minimum_msat: 0,
2306                         htlc_maximum_msat: OptionalField::Present(100_000),
2307                         fee_base_msat: 0,
2308                         fee_proportional_millionths: 0,
2309                         excess_data: Vec::new()
2310                 });
2311                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2312                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2313                         short_channel_id: 12,
2314                         timestamp: 2,
2315                         flags: 2,
2316                         cltv_expiry_delta: 0,
2317                         htlc_minimum_msat: 0,
2318                         htlc_maximum_msat: OptionalField::Present(100_000),
2319                         fee_base_msat: 0,
2320                         fee_proportional_millionths: 0,
2321                         excess_data: Vec::new()
2322                 });
2323
2324                 // Make the first channel (#1) very permissive,
2325                 // and we will be testing all limits on the second channel.
2326                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2327                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2328                         short_channel_id: 1,
2329                         timestamp: 2,
2330                         flags: 0,
2331                         cltv_expiry_delta: 0,
2332                         htlc_minimum_msat: 0,
2333                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2334                         fee_base_msat: 0,
2335                         fee_proportional_millionths: 0,
2336                         excess_data: Vec::new()
2337                 });
2338
2339                 // First, let's see if routing works if we have absolutely no idea about the available amount.
2340                 // In this case, it should be set to 250_000 sats.
2341                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2342                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2343                         short_channel_id: 3,
2344                         timestamp: 2,
2345                         flags: 0,
2346                         cltv_expiry_delta: 0,
2347                         htlc_minimum_msat: 0,
2348                         htlc_maximum_msat: OptionalField::Absent,
2349                         fee_base_msat: 0,
2350                         fee_proportional_millionths: 0,
2351                         excess_data: Vec::new()
2352                 });
2353
2354                 {
2355                         // Attempt to route more than available results in a failure.
2356                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2357                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000_001, 42, Arc::clone(&logger)) {
2358                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2359                         } else { panic!(); }
2360                 }
2361
2362                 {
2363                         // Now, attempt to route an exact amount we have should be fine.
2364                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2365                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000_000, 42, Arc::clone(&logger)).unwrap();
2366                         assert_eq!(route.paths.len(), 1);
2367                         let path = route.paths.last().unwrap();
2368                         assert_eq!(path.len(), 2);
2369                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2370                         assert_eq!(path.last().unwrap().fee_msat, 250_000_000);
2371                 }
2372
2373                 // Check that setting outbound_capacity_msat in first_hops limits the channels.
2374                 // Disable channel #1 and use another first hop.
2375                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2376                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2377                         short_channel_id: 1,
2378                         timestamp: 3,
2379                         flags: 2,
2380                         cltv_expiry_delta: 0,
2381                         htlc_minimum_msat: 0,
2382                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2383                         fee_base_msat: 0,
2384                         fee_proportional_millionths: 0,
2385                         excess_data: Vec::new()
2386                 });
2387
2388                 // Now, limit the first_hop by the outbound_capacity_msat of 200_000 sats.
2389                 let our_chans = vec![channelmanager::ChannelDetails {
2390                         channel_id: [0; 32],
2391                         short_channel_id: Some(42),
2392                         remote_network_id: nodes[0].clone(),
2393                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2394                         channel_value_satoshis: 0,
2395                         user_id: 0,
2396                         outbound_capacity_msat: 200_000_000,
2397                         inbound_capacity_msat: 0,
2398                         is_live: true,
2399                         counterparty_forwarding_info: None,
2400                 }];
2401
2402                 {
2403                         // Attempt to route more than available results in a failure.
2404                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2405                                         Some(InvoiceFeatures::known()), Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_001, 42, Arc::clone(&logger)) {
2406                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2407                         } else { panic!(); }
2408                 }
2409
2410                 {
2411                         // Now, attempt to route an exact amount we have should be fine.
2412                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2413                                 Some(InvoiceFeatures::known()), Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_000, 42, Arc::clone(&logger)).unwrap();
2414                         assert_eq!(route.paths.len(), 1);
2415                         let path = route.paths.last().unwrap();
2416                         assert_eq!(path.len(), 2);
2417                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2418                         assert_eq!(path.last().unwrap().fee_msat, 200_000_000);
2419                 }
2420
2421                 // Enable channel #1 back.
2422                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2423                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2424                         short_channel_id: 1,
2425                         timestamp: 4,
2426                         flags: 0,
2427                         cltv_expiry_delta: 0,
2428                         htlc_minimum_msat: 0,
2429                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2430                         fee_base_msat: 0,
2431                         fee_proportional_millionths: 0,
2432                         excess_data: Vec::new()
2433                 });
2434
2435
2436                 // Now let's see if routing works if we know only htlc_maximum_msat.
2437                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2438                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2439                         short_channel_id: 3,
2440                         timestamp: 3,
2441                         flags: 0,
2442                         cltv_expiry_delta: 0,
2443                         htlc_minimum_msat: 0,
2444                         htlc_maximum_msat: OptionalField::Present(15_000),
2445                         fee_base_msat: 0,
2446                         fee_proportional_millionths: 0,
2447                         excess_data: Vec::new()
2448                 });
2449
2450                 {
2451                         // Attempt to route more than available results in a failure.
2452                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2453                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 15_001, 42, Arc::clone(&logger)) {
2454                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2455                         } else { panic!(); }
2456                 }
2457
2458                 {
2459                         // Now, attempt to route an exact amount we have should be fine.
2460                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2461                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 15_000, 42, Arc::clone(&logger)).unwrap();
2462                         assert_eq!(route.paths.len(), 1);
2463                         let path = route.paths.last().unwrap();
2464                         assert_eq!(path.len(), 2);
2465                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2466                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
2467                 }
2468
2469                 // Now let's see if routing works if we know only capacity from the UTXO.
2470
2471                 // We can't change UTXO capacity on the fly, so we'll disable
2472                 // the existing channel and add another one with the capacity we need.
2473                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2474                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2475                         short_channel_id: 3,
2476                         timestamp: 4,
2477                         flags: 2,
2478                         cltv_expiry_delta: 0,
2479                         htlc_minimum_msat: 0,
2480                         htlc_maximum_msat: OptionalField::Absent,
2481                         fee_base_msat: 0,
2482                         fee_proportional_millionths: 0,
2483                         excess_data: Vec::new()
2484                 });
2485
2486                 let good_script = Builder::new().push_opcode(opcodes::all::OP_PUSHNUM_2)
2487                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[0]).serialize())
2488                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[2]).serialize())
2489                 .push_opcode(opcodes::all::OP_PUSHNUM_2)
2490                 .push_opcode(opcodes::all::OP_CHECKMULTISIG).into_script().to_v0_p2wsh();
2491
2492                 *chain_monitor.utxo_ret.lock().unwrap() = Ok(TxOut { value: 15, script_pubkey: good_script.clone() });
2493                 net_graph_msg_handler.add_chain_access(Some(chain_monitor));
2494
2495                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 333);
2496                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2497                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2498                         short_channel_id: 333,
2499                         timestamp: 1,
2500                         flags: 0,
2501                         cltv_expiry_delta: (3 << 8) | 1,
2502                         htlc_minimum_msat: 0,
2503                         htlc_maximum_msat: OptionalField::Absent,
2504                         fee_base_msat: 0,
2505                         fee_proportional_millionths: 0,
2506                         excess_data: Vec::new()
2507                 });
2508                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2509                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2510                         short_channel_id: 333,
2511                         timestamp: 1,
2512                         flags: 1,
2513                         cltv_expiry_delta: (3 << 8) | 2,
2514                         htlc_minimum_msat: 0,
2515                         htlc_maximum_msat: OptionalField::Absent,
2516                         fee_base_msat: 100,
2517                         fee_proportional_millionths: 0,
2518                         excess_data: Vec::new()
2519                 });
2520
2521                 {
2522                         // Attempt to route more than available results in a failure.
2523                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2524                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 15_001, 42, Arc::clone(&logger)) {
2525                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2526                         } else { panic!(); }
2527                 }
2528
2529                 {
2530                         // Now, attempt to route an exact amount we have should be fine.
2531                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2532                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 15_000, 42, Arc::clone(&logger)).unwrap();
2533                         assert_eq!(route.paths.len(), 1);
2534                         let path = route.paths.last().unwrap();
2535                         assert_eq!(path.len(), 2);
2536                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2537                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
2538                 }
2539
2540                 // Now let's see if routing chooses htlc_maximum_msat over UTXO capacity.
2541                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2542                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2543                         short_channel_id: 333,
2544                         timestamp: 6,
2545                         flags: 0,
2546                         cltv_expiry_delta: 0,
2547                         htlc_minimum_msat: 0,
2548                         htlc_maximum_msat: OptionalField::Present(10_000),
2549                         fee_base_msat: 0,
2550                         fee_proportional_millionths: 0,
2551                         excess_data: Vec::new()
2552                 });
2553
2554                 {
2555                         // Attempt to route more than available results in a failure.
2556                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2557                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 10_001, 42, Arc::clone(&logger)) {
2558                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2559                         } else { panic!(); }
2560                 }
2561
2562                 {
2563                         // Now, attempt to route an exact amount we have should be fine.
2564                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2565                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 10_000, 42, Arc::clone(&logger)).unwrap();
2566                         assert_eq!(route.paths.len(), 1);
2567                         let path = route.paths.last().unwrap();
2568                         assert_eq!(path.len(), 2);
2569                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2570                         assert_eq!(path.last().unwrap().fee_msat, 10_000);
2571                 }
2572         }
2573
2574         #[test]
2575         fn available_liquidity_last_hop_test() {
2576                 // Check that available liquidity properly limits the path even when only
2577                 // one of the latter hops is limited.
2578                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2579                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2580
2581                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
2582                 // {12, 13, 11} have the capacities of 100, {6} has a capacity of 50.
2583                 // Total capacity: 50 sats.
2584
2585                 // Disable other potential paths.
2586                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2587                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2588                         short_channel_id: 2,
2589                         timestamp: 2,
2590                         flags: 2,
2591                         cltv_expiry_delta: 0,
2592                         htlc_minimum_msat: 0,
2593                         htlc_maximum_msat: OptionalField::Present(100_000),
2594                         fee_base_msat: 0,
2595                         fee_proportional_millionths: 0,
2596                         excess_data: Vec::new()
2597                 });
2598                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2599                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2600                         short_channel_id: 7,
2601                         timestamp: 2,
2602                         flags: 2,
2603                         cltv_expiry_delta: 0,
2604                         htlc_minimum_msat: 0,
2605                         htlc_maximum_msat: OptionalField::Present(100_000),
2606                         fee_base_msat: 0,
2607                         fee_proportional_millionths: 0,
2608                         excess_data: Vec::new()
2609                 });
2610
2611                 // Limit capacities
2612
2613                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2614                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2615                         short_channel_id: 12,
2616                         timestamp: 2,
2617                         flags: 0,
2618                         cltv_expiry_delta: 0,
2619                         htlc_minimum_msat: 0,
2620                         htlc_maximum_msat: OptionalField::Present(100_000),
2621                         fee_base_msat: 0,
2622                         fee_proportional_millionths: 0,
2623                         excess_data: Vec::new()
2624                 });
2625                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2626                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2627                         short_channel_id: 13,
2628                         timestamp: 2,
2629                         flags: 0,
2630                         cltv_expiry_delta: 0,
2631                         htlc_minimum_msat: 0,
2632                         htlc_maximum_msat: OptionalField::Present(100_000),
2633                         fee_base_msat: 0,
2634                         fee_proportional_millionths: 0,
2635                         excess_data: Vec::new()
2636                 });
2637
2638                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2639                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2640                         short_channel_id: 6,
2641                         timestamp: 2,
2642                         flags: 0,
2643                         cltv_expiry_delta: 0,
2644                         htlc_minimum_msat: 0,
2645                         htlc_maximum_msat: OptionalField::Present(50_000),
2646                         fee_base_msat: 0,
2647                         fee_proportional_millionths: 0,
2648                         excess_data: Vec::new()
2649                 });
2650                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
2651                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2652                         short_channel_id: 11,
2653                         timestamp: 2,
2654                         flags: 0,
2655                         cltv_expiry_delta: 0,
2656                         htlc_minimum_msat: 0,
2657                         htlc_maximum_msat: OptionalField::Present(100_000),
2658                         fee_base_msat: 0,
2659                         fee_proportional_millionths: 0,
2660                         excess_data: Vec::new()
2661                 });
2662                 {
2663                         // Attempt to route more than available results in a failure.
2664                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2665                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)) {
2666                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2667                         } else { panic!(); }
2668                 }
2669
2670                 {
2671                         // Now, attempt to route 49 sats (just a bit below the capacity).
2672                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2673                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 49_000, 42, Arc::clone(&logger)).unwrap();
2674                         assert_eq!(route.paths.len(), 1);
2675                         let mut total_amount_paid_msat = 0;
2676                         for path in &route.paths {
2677                                 assert_eq!(path.len(), 4);
2678                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
2679                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2680                         }
2681                         assert_eq!(total_amount_paid_msat, 49_000);
2682                 }
2683
2684                 {
2685                         // Attempt to route an exact amount is also fine
2686                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2687                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
2688                         assert_eq!(route.paths.len(), 1);
2689                         let mut total_amount_paid_msat = 0;
2690                         for path in &route.paths {
2691                                 assert_eq!(path.len(), 4);
2692                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
2693                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2694                         }
2695                         assert_eq!(total_amount_paid_msat, 50_000);
2696                 }
2697         }
2698
2699         #[test]
2700         fn ignore_fee_first_hop_test() {
2701                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2702                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2703
2704                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
2705                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2706                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2707                         short_channel_id: 1,
2708                         timestamp: 2,
2709                         flags: 0,
2710                         cltv_expiry_delta: 0,
2711                         htlc_minimum_msat: 0,
2712                         htlc_maximum_msat: OptionalField::Present(100_000),
2713                         fee_base_msat: 1_000_000,
2714                         fee_proportional_millionths: 0,
2715                         excess_data: Vec::new()
2716                 });
2717                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2718                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2719                         short_channel_id: 3,
2720                         timestamp: 2,
2721                         flags: 0,
2722                         cltv_expiry_delta: 0,
2723                         htlc_minimum_msat: 0,
2724                         htlc_maximum_msat: OptionalField::Present(50_000),
2725                         fee_base_msat: 0,
2726                         fee_proportional_millionths: 0,
2727                         excess_data: Vec::new()
2728                 });
2729
2730                 {
2731                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
2732                         assert_eq!(route.paths.len(), 1);
2733                         let mut total_amount_paid_msat = 0;
2734                         for path in &route.paths {
2735                                 assert_eq!(path.len(), 2);
2736                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2737                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2738                         }
2739                         assert_eq!(total_amount_paid_msat, 50_000);
2740                 }
2741         }
2742
2743         #[test]
2744         fn simple_mpp_route_test() {
2745                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2746                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2747
2748                 // We need a route consisting of 3 paths:
2749                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
2750                 // To achieve this, the amount being transferred should be around
2751                 // the total capacity of these 3 paths.
2752
2753                 // First, we set limits on these (previously unlimited) channels.
2754                 // Their aggregate capacity will be 50 + 60 + 180 = 290 sats.
2755
2756                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
2757                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2758                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2759                         short_channel_id: 1,
2760                         timestamp: 2,
2761                         flags: 0,
2762                         cltv_expiry_delta: 0,
2763                         htlc_minimum_msat: 0,
2764                         htlc_maximum_msat: OptionalField::Present(100_000),
2765                         fee_base_msat: 0,
2766                         fee_proportional_millionths: 0,
2767                         excess_data: Vec::new()
2768                 });
2769                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2770                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2771                         short_channel_id: 3,
2772                         timestamp: 2,
2773                         flags: 0,
2774                         cltv_expiry_delta: 0,
2775                         htlc_minimum_msat: 0,
2776                         htlc_maximum_msat: OptionalField::Present(50_000),
2777                         fee_base_msat: 0,
2778                         fee_proportional_millionths: 0,
2779                         excess_data: Vec::new()
2780                 });
2781
2782                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats
2783                 // (total limit 60).
2784                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2785                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2786                         short_channel_id: 12,
2787                         timestamp: 2,
2788                         flags: 0,
2789                         cltv_expiry_delta: 0,
2790                         htlc_minimum_msat: 0,
2791                         htlc_maximum_msat: OptionalField::Present(60_000),
2792                         fee_base_msat: 0,
2793                         fee_proportional_millionths: 0,
2794                         excess_data: Vec::new()
2795                 });
2796                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2797                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2798                         short_channel_id: 13,
2799                         timestamp: 2,
2800                         flags: 0,
2801                         cltv_expiry_delta: 0,
2802                         htlc_minimum_msat: 0,
2803                         htlc_maximum_msat: OptionalField::Present(60_000),
2804                         fee_base_msat: 0,
2805                         fee_proportional_millionths: 0,
2806                         excess_data: Vec::new()
2807                 });
2808
2809                 // Path via node1 is channels {2, 4}. Limit them to 200 and 180 sats
2810                 // (total capacity 180 sats).
2811                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2812                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2813                         short_channel_id: 2,
2814                         timestamp: 2,
2815                         flags: 0,
2816                         cltv_expiry_delta: 0,
2817                         htlc_minimum_msat: 0,
2818                         htlc_maximum_msat: OptionalField::Present(200_000),
2819                         fee_base_msat: 0,
2820                         fee_proportional_millionths: 0,
2821                         excess_data: Vec::new()
2822                 });
2823                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2824                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2825                         short_channel_id: 4,
2826                         timestamp: 2,
2827                         flags: 0,
2828                         cltv_expiry_delta: 0,
2829                         htlc_minimum_msat: 0,
2830                         htlc_maximum_msat: OptionalField::Present(180_000),
2831                         fee_base_msat: 0,
2832                         fee_proportional_millionths: 0,
2833                         excess_data: Vec::new()
2834                 });
2835
2836                 {
2837                         // Attempt to route more than available results in a failure.
2838                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(),
2839                                         &nodes[2], Some(InvoiceFeatures::known()), None, &Vec::new(), 300_000, 42, Arc::clone(&logger)) {
2840                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2841                         } else { panic!(); }
2842                 }
2843
2844                 {
2845                         // Now, attempt to route 250 sats (just a bit below the capacity).
2846                         // Our algorithm should provide us with these 3 paths.
2847                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2848                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000, 42, Arc::clone(&logger)).unwrap();
2849                         assert_eq!(route.paths.len(), 3);
2850                         let mut total_amount_paid_msat = 0;
2851                         for path in &route.paths {
2852                                 assert_eq!(path.len(), 2);
2853                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2854                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2855                         }
2856                         assert_eq!(total_amount_paid_msat, 250_000);
2857                 }
2858
2859                 {
2860                         // Attempt to route an exact amount is also fine
2861                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2862                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 290_000, 42, Arc::clone(&logger)).unwrap();
2863                         assert_eq!(route.paths.len(), 3);
2864                         let mut total_amount_paid_msat = 0;
2865                         for path in &route.paths {
2866                                 assert_eq!(path.len(), 2);
2867                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2868                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2869                         }
2870                         assert_eq!(total_amount_paid_msat, 290_000);
2871                 }
2872         }
2873
2874         #[test]
2875         fn long_mpp_route_test() {
2876                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2877                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2878
2879                 // We need a route consisting of 3 paths:
2880                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
2881                 // Note that these paths overlap (channels 5, 12, 13).
2882                 // We will route 300 sats.
2883                 // Each path will have 100 sats capacity, those channels which
2884                 // are used twice will have 200 sats capacity.
2885
2886                 // Disable other potential paths.
2887                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2888                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2889                         short_channel_id: 2,
2890                         timestamp: 2,
2891                         flags: 2,
2892                         cltv_expiry_delta: 0,
2893                         htlc_minimum_msat: 0,
2894                         htlc_maximum_msat: OptionalField::Present(100_000),
2895                         fee_base_msat: 0,
2896                         fee_proportional_millionths: 0,
2897                         excess_data: Vec::new()
2898                 });
2899                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2900                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2901                         short_channel_id: 7,
2902                         timestamp: 2,
2903                         flags: 2,
2904                         cltv_expiry_delta: 0,
2905                         htlc_minimum_msat: 0,
2906                         htlc_maximum_msat: OptionalField::Present(100_000),
2907                         fee_base_msat: 0,
2908                         fee_proportional_millionths: 0,
2909                         excess_data: Vec::new()
2910                 });
2911
2912                 // Path via {node0, node2} is channels {1, 3, 5}.
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: 2,
2917                         flags: 0,
2918                         cltv_expiry_delta: 0,
2919                         htlc_minimum_msat: 0,
2920                         htlc_maximum_msat: OptionalField::Present(100_000),
2921                         fee_base_msat: 0,
2922                         fee_proportional_millionths: 0,
2923                         excess_data: Vec::new()
2924                 });
2925                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2926                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2927                         short_channel_id: 3,
2928                         timestamp: 2,
2929                         flags: 0,
2930                         cltv_expiry_delta: 0,
2931                         htlc_minimum_msat: 0,
2932                         htlc_maximum_msat: OptionalField::Present(100_000),
2933                         fee_base_msat: 0,
2934                         fee_proportional_millionths: 0,
2935                         excess_data: Vec::new()
2936                 });
2937
2938                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
2939                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
2940                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2941                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2942                         short_channel_id: 5,
2943                         timestamp: 2,
2944                         flags: 0,
2945                         cltv_expiry_delta: 0,
2946                         htlc_minimum_msat: 0,
2947                         htlc_maximum_msat: OptionalField::Present(200_000),
2948                         fee_base_msat: 0,
2949                         fee_proportional_millionths: 0,
2950                         excess_data: Vec::new()
2951                 });
2952
2953                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
2954                 // Add 100 sats to the capacities of {12, 13}, because these channels
2955                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
2956                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2957                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2958                         short_channel_id: 12,
2959                         timestamp: 2,
2960                         flags: 0,
2961                         cltv_expiry_delta: 0,
2962                         htlc_minimum_msat: 0,
2963                         htlc_maximum_msat: OptionalField::Present(200_000),
2964                         fee_base_msat: 0,
2965                         fee_proportional_millionths: 0,
2966                         excess_data: Vec::new()
2967                 });
2968                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2969                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2970                         short_channel_id: 13,
2971                         timestamp: 2,
2972                         flags: 0,
2973                         cltv_expiry_delta: 0,
2974                         htlc_minimum_msat: 0,
2975                         htlc_maximum_msat: OptionalField::Present(200_000),
2976                         fee_base_msat: 0,
2977                         fee_proportional_millionths: 0,
2978                         excess_data: Vec::new()
2979                 });
2980
2981                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2982                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2983                         short_channel_id: 6,
2984                         timestamp: 2,
2985                         flags: 0,
2986                         cltv_expiry_delta: 0,
2987                         htlc_minimum_msat: 0,
2988                         htlc_maximum_msat: OptionalField::Present(100_000),
2989                         fee_base_msat: 0,
2990                         fee_proportional_millionths: 0,
2991                         excess_data: Vec::new()
2992                 });
2993                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
2994                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2995                         short_channel_id: 11,
2996                         timestamp: 2,
2997                         flags: 0,
2998                         cltv_expiry_delta: 0,
2999                         htlc_minimum_msat: 0,
3000                         htlc_maximum_msat: OptionalField::Present(100_000),
3001                         fee_base_msat: 0,
3002                         fee_proportional_millionths: 0,
3003                         excess_data: Vec::new()
3004                 });
3005
3006                 // Path via {node7, node2} is channels {12, 13, 5}.
3007                 // We already limited them to 200 sats (they are used twice for 100 sats).
3008                 // Nothing to do here.
3009
3010                 {
3011                         // Attempt to route more than available results in a failure.
3012                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3013                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 350_000, 42, Arc::clone(&logger)) {
3014                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3015                         } else { panic!(); }
3016                 }
3017
3018                 {
3019                         // Now, attempt to route 300 sats (exact amount we can route).
3020                         // Our algorithm should provide us with these 3 paths, 100 sats each.
3021                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3022                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 300_000, 42, Arc::clone(&logger)).unwrap();
3023                         assert_eq!(route.paths.len(), 3);
3024
3025                         let mut total_amount_paid_msat = 0;
3026                         for path in &route.paths {
3027                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3028                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3029                         }
3030                         assert_eq!(total_amount_paid_msat, 300_000);
3031                 }
3032
3033         }
3034
3035         #[test]
3036         fn mpp_cheaper_route_test() {
3037                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3038                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3039
3040                 // This test checks that if we have two cheaper paths and one more expensive path,
3041                 // so that liquidity-wise any 2 of 3 combination is sufficient,
3042                 // two cheaper paths will be taken.
3043                 // These paths have equal available liquidity.
3044
3045                 // We need a combination of 3 paths:
3046                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
3047                 // Note that these paths overlap (channels 5, 12, 13).
3048                 // Each path will have 100 sats capacity, those channels which
3049                 // are used twice will have 200 sats capacity.
3050
3051                 // Disable other potential paths.
3052                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3053                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3054                         short_channel_id: 2,
3055                         timestamp: 2,
3056                         flags: 2,
3057                         cltv_expiry_delta: 0,
3058                         htlc_minimum_msat: 0,
3059                         htlc_maximum_msat: OptionalField::Present(100_000),
3060                         fee_base_msat: 0,
3061                         fee_proportional_millionths: 0,
3062                         excess_data: Vec::new()
3063                 });
3064                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3065                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3066                         short_channel_id: 7,
3067                         timestamp: 2,
3068                         flags: 2,
3069                         cltv_expiry_delta: 0,
3070                         htlc_minimum_msat: 0,
3071                         htlc_maximum_msat: OptionalField::Present(100_000),
3072                         fee_base_msat: 0,
3073                         fee_proportional_millionths: 0,
3074                         excess_data: Vec::new()
3075                 });
3076
3077                 // Path via {node0, node2} is channels {1, 3, 5}.
3078                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3079                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3080                         short_channel_id: 1,
3081                         timestamp: 2,
3082                         flags: 0,
3083                         cltv_expiry_delta: 0,
3084                         htlc_minimum_msat: 0,
3085                         htlc_maximum_msat: OptionalField::Present(100_000),
3086                         fee_base_msat: 0,
3087                         fee_proportional_millionths: 0,
3088                         excess_data: Vec::new()
3089                 });
3090                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3091                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3092                         short_channel_id: 3,
3093                         timestamp: 2,
3094                         flags: 0,
3095                         cltv_expiry_delta: 0,
3096                         htlc_minimum_msat: 0,
3097                         htlc_maximum_msat: OptionalField::Present(100_000),
3098                         fee_base_msat: 0,
3099                         fee_proportional_millionths: 0,
3100                         excess_data: Vec::new()
3101                 });
3102
3103                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3104                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3105                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3106                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3107                         short_channel_id: 5,
3108                         timestamp: 2,
3109                         flags: 0,
3110                         cltv_expiry_delta: 0,
3111                         htlc_minimum_msat: 0,
3112                         htlc_maximum_msat: OptionalField::Present(200_000),
3113                         fee_base_msat: 0,
3114                         fee_proportional_millionths: 0,
3115                         excess_data: Vec::new()
3116                 });
3117
3118                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3119                 // Add 100 sats to the capacities of {12, 13}, because these channels
3120                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3121                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3122                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3123                         short_channel_id: 12,
3124                         timestamp: 2,
3125                         flags: 0,
3126                         cltv_expiry_delta: 0,
3127                         htlc_minimum_msat: 0,
3128                         htlc_maximum_msat: OptionalField::Present(200_000),
3129                         fee_base_msat: 0,
3130                         fee_proportional_millionths: 0,
3131                         excess_data: Vec::new()
3132                 });
3133                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3134                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3135                         short_channel_id: 13,
3136                         timestamp: 2,
3137                         flags: 0,
3138                         cltv_expiry_delta: 0,
3139                         htlc_minimum_msat: 0,
3140                         htlc_maximum_msat: OptionalField::Present(200_000),
3141                         fee_base_msat: 0,
3142                         fee_proportional_millionths: 0,
3143                         excess_data: Vec::new()
3144                 });
3145
3146                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3147                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3148                         short_channel_id: 6,
3149                         timestamp: 2,
3150                         flags: 0,
3151                         cltv_expiry_delta: 0,
3152                         htlc_minimum_msat: 0,
3153                         htlc_maximum_msat: OptionalField::Present(100_000),
3154                         fee_base_msat: 1_000,
3155                         fee_proportional_millionths: 0,
3156                         excess_data: Vec::new()
3157                 });
3158                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3159                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3160                         short_channel_id: 11,
3161                         timestamp: 2,
3162                         flags: 0,
3163                         cltv_expiry_delta: 0,
3164                         htlc_minimum_msat: 0,
3165                         htlc_maximum_msat: OptionalField::Present(100_000),
3166                         fee_base_msat: 0,
3167                         fee_proportional_millionths: 0,
3168                         excess_data: Vec::new()
3169                 });
3170
3171                 // Path via {node7, node2} is channels {12, 13, 5}.
3172                 // We already limited them to 200 sats (they are used twice for 100 sats).
3173                 // Nothing to do here.
3174
3175                 {
3176                         // Now, attempt to route 180 sats.
3177                         // Our algorithm should provide us with these 2 paths.
3178                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3179                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 180_000, 42, Arc::clone(&logger)).unwrap();
3180                         assert_eq!(route.paths.len(), 2);
3181
3182                         let mut total_value_transferred_msat = 0;
3183                         let mut total_paid_msat = 0;
3184                         for path in &route.paths {
3185                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3186                                 total_value_transferred_msat += path.last().unwrap().fee_msat;
3187                                 for hop in path {
3188                                         total_paid_msat += hop.fee_msat;
3189                                 }
3190                         }
3191                         // If we paid fee, this would be higher.
3192                         assert_eq!(total_value_transferred_msat, 180_000);
3193                         let total_fees_paid = total_paid_msat - total_value_transferred_msat;
3194                         assert_eq!(total_fees_paid, 0);
3195                 }
3196         }
3197
3198         #[test]
3199         fn fees_on_mpp_route_test() {
3200                 // This test makes sure that MPP algorithm properly takes into account
3201                 // fees charged on the channels, by making the fees impactful:
3202                 // if the fee is not properly accounted for, the behavior is different.
3203                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3204                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3205
3206                 // We need a route consisting of 2 paths:
3207                 // From our node to node3 via {node0, node2} and {node7, node2, node4}.
3208                 // We will route 200 sats, Each path will have 100 sats capacity.
3209
3210                 // This test is not particularly stable: e.g.,
3211                 // there's a way to route via {node0, node2, node4}.
3212                 // It works while pathfinding is deterministic, but can be broken otherwise.
3213                 // It's fine to ignore this concern for now.
3214
3215                 // Disable other potential paths.
3216                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3217                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3218                         short_channel_id: 2,
3219                         timestamp: 2,
3220                         flags: 2,
3221                         cltv_expiry_delta: 0,
3222                         htlc_minimum_msat: 0,
3223                         htlc_maximum_msat: OptionalField::Present(100_000),
3224                         fee_base_msat: 0,
3225                         fee_proportional_millionths: 0,
3226                         excess_data: Vec::new()
3227                 });
3228
3229                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3230                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3231                         short_channel_id: 7,
3232                         timestamp: 2,
3233                         flags: 2,
3234                         cltv_expiry_delta: 0,
3235                         htlc_minimum_msat: 0,
3236                         htlc_maximum_msat: OptionalField::Present(100_000),
3237                         fee_base_msat: 0,
3238                         fee_proportional_millionths: 0,
3239                         excess_data: Vec::new()
3240                 });
3241
3242                 // Path via {node0, node2} is channels {1, 3, 5}.
3243                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3244                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3245                         short_channel_id: 1,
3246                         timestamp: 2,
3247                         flags: 0,
3248                         cltv_expiry_delta: 0,
3249                         htlc_minimum_msat: 0,
3250                         htlc_maximum_msat: OptionalField::Present(100_000),
3251                         fee_base_msat: 0,
3252                         fee_proportional_millionths: 0,
3253                         excess_data: Vec::new()
3254                 });
3255                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3256                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3257                         short_channel_id: 3,
3258                         timestamp: 2,
3259                         flags: 0,
3260                         cltv_expiry_delta: 0,
3261                         htlc_minimum_msat: 0,
3262                         htlc_maximum_msat: OptionalField::Present(100_000),
3263                         fee_base_msat: 0,
3264                         fee_proportional_millionths: 0,
3265                         excess_data: Vec::new()
3266                 });
3267
3268                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3269                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3270                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3271                         short_channel_id: 5,
3272                         timestamp: 2,
3273                         flags: 0,
3274                         cltv_expiry_delta: 0,
3275                         htlc_minimum_msat: 0,
3276                         htlc_maximum_msat: OptionalField::Present(100_000),
3277                         fee_base_msat: 0,
3278                         fee_proportional_millionths: 0,
3279                         excess_data: Vec::new()
3280                 });
3281
3282                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3283                 // All channels should be 100 sats capacity. But for the fee experiment,
3284                 // we'll add absolute fee of 150 sats paid for the use channel 6 (paid to node2 on channel 13).
3285                 // Since channel 12 allows to deliver only 250 sats to channel 13, channel 13 can transfer only
3286                 // 100 sats (and pay 150 sats in fees for the use of channel 6),
3287                 // so no matter how large are other channels,
3288                 // the whole path will be limited by 100 sats with just these 2 conditions:
3289                 // - channel 12 capacity is 250 sats
3290                 // - fee for channel 6 is 150 sats
3291                 // Let's test this by enforcing these 2 conditions and removing other limits.
3292                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3293                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3294                         short_channel_id: 12,
3295                         timestamp: 2,
3296                         flags: 0,
3297                         cltv_expiry_delta: 0,
3298                         htlc_minimum_msat: 0,
3299                         htlc_maximum_msat: OptionalField::Present(250_000),
3300                         fee_base_msat: 0,
3301                         fee_proportional_millionths: 0,
3302                         excess_data: Vec::new()
3303                 });
3304                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3305                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3306                         short_channel_id: 13,
3307                         timestamp: 2,
3308                         flags: 0,
3309                         cltv_expiry_delta: 0,
3310                         htlc_minimum_msat: 0,
3311                         htlc_maximum_msat: OptionalField::Absent,
3312                         fee_base_msat: 0,
3313                         fee_proportional_millionths: 0,
3314                         excess_data: Vec::new()
3315                 });
3316
3317                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3318                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3319                         short_channel_id: 6,
3320                         timestamp: 2,
3321                         flags: 0,
3322                         cltv_expiry_delta: 0,
3323                         htlc_minimum_msat: 0,
3324                         htlc_maximum_msat: OptionalField::Absent,
3325                         fee_base_msat: 150_000,
3326                         fee_proportional_millionths: 0,
3327                         excess_data: Vec::new()
3328                 });
3329                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3330                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3331                         short_channel_id: 11,
3332                         timestamp: 2,
3333                         flags: 0,
3334                         cltv_expiry_delta: 0,
3335                         htlc_minimum_msat: 0,
3336                         htlc_maximum_msat: OptionalField::Absent,
3337                         fee_base_msat: 0,
3338                         fee_proportional_millionths: 0,
3339                         excess_data: Vec::new()
3340                 });
3341
3342                 {
3343                         // Attempt to route more than available results in a failure.
3344                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3345                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 210_000, 42, Arc::clone(&logger)) {
3346                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3347                         } else { panic!(); }
3348                 }
3349
3350                 {
3351                         // Now, attempt to route 200 sats (exact amount we can route).
3352                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3353                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 200_000, 42, Arc::clone(&logger)).unwrap();
3354                         assert_eq!(route.paths.len(), 2);
3355
3356                         let mut total_amount_paid_msat = 0;
3357                         for path in &route.paths {
3358                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3359                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3360                         }
3361                         assert_eq!(total_amount_paid_msat, 200_000);
3362                 }
3363
3364         }
3365
3366         #[test]
3367         fn drop_lowest_channel_mpp_route_test() {
3368                 // This test checks that low-capacity channel is dropped when after
3369                 // path finding we realize that we found more capacity than we need.
3370                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3371                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3372
3373                 // We need a route consisting of 3 paths:
3374                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
3375
3376                 // The first and the second paths should be sufficient, but the third should be
3377                 // cheaper, so that we select it but drop later.
3378
3379                 // First, we set limits on these (previously unlimited) channels.
3380                 // Their aggregate capacity will be 50 + 60 + 20 = 130 sats.
3381
3382                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50);
3383                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3384                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3385                         short_channel_id: 1,
3386                         timestamp: 2,
3387                         flags: 0,
3388                         cltv_expiry_delta: 0,
3389                         htlc_minimum_msat: 0,
3390                         htlc_maximum_msat: OptionalField::Present(100_000),
3391                         fee_base_msat: 0,
3392                         fee_proportional_millionths: 0,
3393                         excess_data: Vec::new()
3394                 });
3395                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3396                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3397                         short_channel_id: 3,
3398                         timestamp: 2,
3399                         flags: 0,
3400                         cltv_expiry_delta: 0,
3401                         htlc_minimum_msat: 0,
3402                         htlc_maximum_msat: OptionalField::Present(50_000),
3403                         fee_base_msat: 100,
3404                         fee_proportional_millionths: 0,
3405                         excess_data: Vec::new()
3406                 });
3407
3408                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats (total limit 60);
3409                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3410                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3411                         short_channel_id: 12,
3412                         timestamp: 2,
3413                         flags: 0,
3414                         cltv_expiry_delta: 0,
3415                         htlc_minimum_msat: 0,
3416                         htlc_maximum_msat: OptionalField::Present(60_000),
3417                         fee_base_msat: 100,
3418                         fee_proportional_millionths: 0,
3419                         excess_data: Vec::new()
3420                 });
3421                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3422                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3423                         short_channel_id: 13,
3424                         timestamp: 2,
3425                         flags: 0,
3426                         cltv_expiry_delta: 0,
3427                         htlc_minimum_msat: 0,
3428                         htlc_maximum_msat: OptionalField::Present(60_000),
3429                         fee_base_msat: 0,
3430                         fee_proportional_millionths: 0,
3431                         excess_data: Vec::new()
3432                 });
3433
3434                 // Path via node1 is channels {2, 4}. Limit them to 20 and 20 sats (total capacity 20 sats).
3435                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3436                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3437                         short_channel_id: 2,
3438                         timestamp: 2,
3439                         flags: 0,
3440                         cltv_expiry_delta: 0,
3441                         htlc_minimum_msat: 0,
3442                         htlc_maximum_msat: OptionalField::Present(20_000),
3443                         fee_base_msat: 0,
3444                         fee_proportional_millionths: 0,
3445                         excess_data: Vec::new()
3446                 });
3447                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3448                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3449                         short_channel_id: 4,
3450                         timestamp: 2,
3451                         flags: 0,
3452                         cltv_expiry_delta: 0,
3453                         htlc_minimum_msat: 0,
3454                         htlc_maximum_msat: OptionalField::Present(20_000),
3455                         fee_base_msat: 0,
3456                         fee_proportional_millionths: 0,
3457                         excess_data: Vec::new()
3458                 });
3459
3460                 {
3461                         // Attempt to route more than available results in a failure.
3462                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3463                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 150_000, 42, Arc::clone(&logger)) {
3464                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3465                         } else { panic!(); }
3466                 }
3467
3468                 {
3469                         // Now, attempt to route 125 sats (just a bit below the capacity of 3 channels).
3470                         // Our algorithm should provide us with these 3 paths.
3471                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3472                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 125_000, 42, Arc::clone(&logger)).unwrap();
3473                         assert_eq!(route.paths.len(), 3);
3474                         let mut total_amount_paid_msat = 0;
3475                         for path in &route.paths {
3476                                 assert_eq!(path.len(), 2);
3477                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3478                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3479                         }
3480                         assert_eq!(total_amount_paid_msat, 125_000);
3481                 }
3482
3483                 {
3484                         // Attempt to route without the last small cheap channel
3485                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3486                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
3487                         assert_eq!(route.paths.len(), 2);
3488                         let mut total_amount_paid_msat = 0;
3489                         for path in &route.paths {
3490                                 assert_eq!(path.len(), 2);
3491                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3492                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3493                         }
3494                         assert_eq!(total_amount_paid_msat, 90_000);
3495                 }
3496         }
3497
3498         #[test]
3499         fn min_criteria_consistency() {
3500                 // Test that we don't use an inconsistent metric between updating and walking nodes during
3501                 // our Dijkstra's pass. In the initial version of MPP, the "best source" for a given node
3502                 // was updated with a different critera from the heap sorting, resulting in loops in
3503                 // calculated paths. We test for that specific case here.
3504
3505                 // We construct a network that looks like this:
3506                 //
3507                 //            node2 -1(3)2- node3
3508                 //              2          2
3509                 //               (2)     (4)
3510                 //                  1   1
3511                 //    node1 -1(5)2- node4 -1(1)2- node6
3512                 //    2
3513                 //   (6)
3514                 //        1
3515                 // our_node
3516                 //
3517                 // We create a loop on the side of our real path - our destination is node 6, with a
3518                 // previous hop of node 4. From 4, the cheapest previous path is channel 2 from node 2,
3519                 // followed by node 3 over channel 3. Thereafter, the cheapest next-hop is back to node 4
3520                 // (this time over channel 4). Channel 4 has 0 htlc_minimum_msat whereas channel 1 (the
3521                 // other channel with a previous-hop of node 4) has a high (but irrelevant to the overall
3522                 // payment) htlc_minimum_msat. In the original algorithm, this resulted in node4's
3523                 // "previous hop" being set to node 3, creating a loop in the path.
3524                 let secp_ctx = Secp256k1::new();
3525                 let logger = Arc::new(test_utils::TestLogger::new());
3526                 let net_graph_msg_handler = NetGraphMsgHandler::new(genesis_block(Network::Testnet).header.block_hash(), None, Arc::clone(&logger));
3527                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3528
3529                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
3530                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3531                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3532                         short_channel_id: 6,
3533                         timestamp: 1,
3534                         flags: 0,
3535                         cltv_expiry_delta: (6 << 8) | 0,
3536                         htlc_minimum_msat: 0,
3537                         htlc_maximum_msat: OptionalField::Absent,
3538                         fee_base_msat: 0,
3539                         fee_proportional_millionths: 0,
3540                         excess_data: Vec::new()
3541                 });
3542                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
3543
3544                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3545                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3546                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3547                         short_channel_id: 5,
3548                         timestamp: 1,
3549                         flags: 0,
3550                         cltv_expiry_delta: (5 << 8) | 0,
3551                         htlc_minimum_msat: 0,
3552                         htlc_maximum_msat: OptionalField::Absent,
3553                         fee_base_msat: 100,
3554                         fee_proportional_millionths: 0,
3555                         excess_data: Vec::new()
3556                 });
3557                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
3558
3559                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
3560                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3561                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3562                         short_channel_id: 4,
3563                         timestamp: 1,
3564                         flags: 0,
3565                         cltv_expiry_delta: (4 << 8) | 0,
3566                         htlc_minimum_msat: 0,
3567                         htlc_maximum_msat: OptionalField::Absent,
3568                         fee_base_msat: 0,
3569                         fee_proportional_millionths: 0,
3570                         excess_data: Vec::new()
3571                 });
3572                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
3573
3574                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
3575                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
3576                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3577                         short_channel_id: 3,
3578                         timestamp: 1,
3579                         flags: 0,
3580                         cltv_expiry_delta: (3 << 8) | 0,
3581                         htlc_minimum_msat: 0,
3582                         htlc_maximum_msat: OptionalField::Absent,
3583                         fee_base_msat: 0,
3584                         fee_proportional_millionths: 0,
3585                         excess_data: Vec::new()
3586                 });
3587                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
3588
3589                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
3590                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3591                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3592                         short_channel_id: 2,
3593                         timestamp: 1,
3594                         flags: 0,
3595                         cltv_expiry_delta: (2 << 8) | 0,
3596                         htlc_minimum_msat: 0,
3597                         htlc_maximum_msat: OptionalField::Absent,
3598                         fee_base_msat: 0,
3599                         fee_proportional_millionths: 0,
3600                         excess_data: Vec::new()
3601                 });
3602
3603                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[6], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
3604                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3605                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3606                         short_channel_id: 1,
3607                         timestamp: 1,
3608                         flags: 0,
3609                         cltv_expiry_delta: (1 << 8) | 0,
3610                         htlc_minimum_msat: 100,
3611                         htlc_maximum_msat: OptionalField::Absent,
3612                         fee_base_msat: 0,
3613                         fee_proportional_millionths: 0,
3614                         excess_data: Vec::new()
3615                 });
3616                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[6], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
3617
3618                 {
3619                         // Now ensure the route flows simply over nodes 1 and 4 to 6.
3620                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &Vec::new(), 10_000, 42, Arc::clone(&logger)).unwrap();
3621                         assert_eq!(route.paths.len(), 1);
3622                         assert_eq!(route.paths[0].len(), 3);
3623
3624                         assert_eq!(route.paths[0][0].pubkey, nodes[1]);
3625                         assert_eq!(route.paths[0][0].short_channel_id, 6);
3626                         assert_eq!(route.paths[0][0].fee_msat, 100);
3627                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (5 << 8) | 0);
3628                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(1));
3629                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(6));
3630
3631                         assert_eq!(route.paths[0][1].pubkey, nodes[4]);
3632                         assert_eq!(route.paths[0][1].short_channel_id, 5);
3633                         assert_eq!(route.paths[0][1].fee_msat, 0);
3634                         assert_eq!(route.paths[0][1].cltv_expiry_delta, (1 << 8) | 0);
3635                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(4));
3636                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(5));
3637
3638                         assert_eq!(route.paths[0][2].pubkey, nodes[6]);
3639                         assert_eq!(route.paths[0][2].short_channel_id, 1);
3640                         assert_eq!(route.paths[0][2].fee_msat, 10_000);
3641                         assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
3642                         assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
3643                         assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(1));
3644                 }
3645         }
3646
3647
3648         #[test]
3649         fn exact_fee_liquidity_limit() {
3650                 // Test that if, while walking the graph, we find a hop that has exactly enough liquidity
3651                 // for us, including later hop fees, we take it. In the first version of our MPP algorithm
3652                 // we calculated fees on a higher value, resulting in us ignoring such paths.
3653                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3654                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3655
3656                 // We modify the graph to set the htlc_maximum of channel 2 to below the value we wish to
3657                 // send.
3658                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3659                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3660                         short_channel_id: 2,
3661                         timestamp: 2,
3662                         flags: 0,
3663                         cltv_expiry_delta: 0,
3664                         htlc_minimum_msat: 0,
3665                         htlc_maximum_msat: OptionalField::Present(85_000),
3666                         fee_base_msat: 0,
3667                         fee_proportional_millionths: 0,
3668                         excess_data: Vec::new()
3669                 });
3670
3671                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3672                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3673                         short_channel_id: 12,
3674                         timestamp: 2,
3675                         flags: 0,
3676                         cltv_expiry_delta: (4 << 8) | 1,
3677                         htlc_minimum_msat: 0,
3678                         htlc_maximum_msat: OptionalField::Present(270_000),
3679                         fee_base_msat: 0,
3680                         fee_proportional_millionths: 1000000,
3681                         excess_data: Vec::new()
3682                 });
3683
3684                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3685                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3686                         short_channel_id: 13,
3687                         timestamp: 2,
3688                         flags: 1 | 2,
3689                         cltv_expiry_delta: (13 << 8) | 2,
3690                         htlc_minimum_msat: 0,
3691                         htlc_maximum_msat: OptionalField::Absent,
3692                         fee_base_msat: 0,
3693                         fee_proportional_millionths: 0,
3694                         excess_data: Vec::new()
3695                 });
3696
3697                 {
3698                         // Now, attempt to route 125 sats (just a bit below the capacity of 3 channels).
3699                         // Our algorithm should provide us with these 3 paths.
3700                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
3701                         assert_eq!(route.paths.len(), 1);
3702                         assert_eq!(route.paths[0].len(), 2);
3703
3704                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
3705                         assert_eq!(route.paths[0][0].short_channel_id, 12);
3706                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
3707                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
3708                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
3709                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
3710
3711                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
3712                         assert_eq!(route.paths[0][1].short_channel_id, 13);
3713                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
3714                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
3715                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
3716                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
3717                 }
3718         }
3719
3720         #[test]
3721         fn htlc_max_reduction_below_min() {
3722                 // Test that if, while walking the graph, we reduce the value being sent to meet an
3723                 // htlc_maximum_msat, we don't end up undershooting a later htlc_minimum_msat. In the
3724                 // initial version of MPP we'd accept such routes but reject them while recalculating fees,
3725                 // resulting in us thinking there is no possible path, even if other paths exist.
3726                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3727                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3728
3729                 // We modify the graph to set the htlc_minimum of channel 2 and 4 as needed - channel 2
3730                 // gets an htlc_minimum_msat of 80_000 and channel 4 an htlc_maximum_msat of 90_000. We
3731                 // then try to send 90_000.
3732                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3733                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3734                         short_channel_id: 2,
3735                         timestamp: 2,
3736                         flags: 0,
3737                         cltv_expiry_delta: 0,
3738                         htlc_minimum_msat: 0,
3739                         htlc_maximum_msat: OptionalField::Present(80_000),
3740                         fee_base_msat: 0,
3741                         fee_proportional_millionths: 0,
3742                         excess_data: Vec::new()
3743                 });
3744                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3745                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3746                         short_channel_id: 4,
3747                         timestamp: 2,
3748                         flags: 0,
3749                         cltv_expiry_delta: (4 << 8) | 1,
3750                         htlc_minimum_msat: 90_000,
3751                         htlc_maximum_msat: OptionalField::Absent,
3752                         fee_base_msat: 0,
3753                         fee_proportional_millionths: 0,
3754                         excess_data: Vec::new()
3755                 });
3756
3757                 {
3758                         // Now, attempt to route 125 sats (just a bit below the capacity of 3 channels).
3759                         // Our algorithm should provide us with these 3 paths.
3760                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], Some(InvoiceFeatures::known()), None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
3761                         assert_eq!(route.paths.len(), 1);
3762                         assert_eq!(route.paths[0].len(), 2);
3763
3764                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
3765                         assert_eq!(route.paths[0][0].short_channel_id, 12);
3766                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
3767                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
3768                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
3769                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
3770
3771                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
3772                         assert_eq!(route.paths[0][1].short_channel_id, 13);
3773                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
3774                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
3775                         assert_eq!(route.paths[0][1].node_features.le_flags(), InvoiceFeatures::known().le_flags());
3776                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
3777                 }
3778         }
3779
3780         /// Tries to open a network graph file, or panics with a URL to fetch it.
3781         pub(super) fn get_route_file() -> std::fs::File {
3782                 File::open("net_graph-2021-02-12.bin") // By default we're run in RL/lightning
3783                         .or_else(|_| File::open("lightning/net_graph-2021-02-12.bin")) // We may be run manually in RL/
3784                         .or_else(|_| { // Fall back to guessing based on the binary location
3785                                 // path is likely something like .../rust-lightning/target/debug/deps/lightning-...
3786                                 let mut path = std::env::current_exe().unwrap();
3787                                 path.pop(); // lightning-...
3788                                 path.pop(); // deps
3789                                 path.pop(); // debug
3790                                 path.pop(); // target
3791                                 path.push("lightning");
3792                                 path.push("net_graph-2021-02-12.bin");
3793                                 eprintln!("{}", path.to_str().unwrap());
3794                                 File::open(path)
3795                         })
3796                         .expect("Please fetch https://bitcoin.ninja/ldk-net_graph-879e309c128-2020-02-12.bin and place it at lightning/net_graph-2021-02-12.bin")
3797         }
3798
3799         pub(super) fn random_init_seed() -> u64 {
3800                 // Because the default HashMap in std pulls OS randomness, we can use it as a (bad) RNG.
3801                 use std::hash::{BuildHasher, Hasher};
3802                 let seed = std::collections::hash_map::RandomState::new().build_hasher().finish();
3803                 println!("Using seed of {}", seed);
3804                 seed
3805         }
3806
3807         use std::fs::File;
3808         use util::ser::Readable;
3809         #[test]
3810         fn generate_routes() {
3811                 let mut d = get_route_file();
3812                 let graph = NetworkGraph::read(&mut d).unwrap();
3813
3814                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3815                 let mut seed = random_init_seed() as usize;
3816                 'load_endpoints: for _ in 0..10 {
3817                         loop {
3818                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3819                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3820                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3821                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3822                                 let amt = seed as u64 % 200_000_000;
3823                                 if get_route(src, &graph, dst, None, None, &[], amt, 42, &test_utils::TestLogger::new()).is_ok() {
3824                                         continue 'load_endpoints;
3825                                 }
3826                         }
3827                 }
3828         }
3829
3830         #[test]
3831         fn generate_routes_mpp() {
3832                 let mut d = get_route_file();
3833                 let graph = NetworkGraph::read(&mut d).unwrap();
3834
3835                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3836                 let mut seed = random_init_seed() as usize;
3837                 'load_endpoints: for _ in 0..10 {
3838                         loop {
3839                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3840                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3841                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3842                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3843                                 let amt = seed as u64 % 200_000_000;
3844                                 if get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &test_utils::TestLogger::new()).is_ok() {
3845                                         continue 'load_endpoints;
3846                                 }
3847                         }
3848                 }
3849         }
3850 }
3851
3852 #[cfg(all(test, feature = "unstable"))]
3853 mod benches {
3854         use super::*;
3855         use util::logger::{Logger, Record};
3856
3857         use std::fs::File;
3858         use test::Bencher;
3859
3860         struct DummyLogger {}
3861         impl Logger for DummyLogger {
3862                 fn log(&self, _record: &Record) {}
3863         }
3864
3865         #[bench]
3866         fn generate_routes(bench: &mut Bencher) {
3867                 let mut d = tests::get_route_file();
3868                 let graph = NetworkGraph::read(&mut d).unwrap();
3869
3870                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3871                 let mut path_endpoints = Vec::new();
3872                 let mut seed: usize = 0xdeadbeef;
3873                 'load_endpoints: for _ in 0..100 {
3874                         loop {
3875                                 seed *= 0xdeadbeef;
3876                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3877                                 seed *= 0xdeadbeef;
3878                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3879                                 let amt = seed as u64 % 1_000_000;
3880                                 if get_route(src, &graph, dst, None, None, &[], amt, 42, &DummyLogger{}).is_ok() {
3881                                         path_endpoints.push((src, dst, amt));
3882                                         continue 'load_endpoints;
3883                                 }
3884                         }
3885                 }
3886
3887                 // ...then benchmark finding paths between the nodes we learned.
3888                 let mut idx = 0;
3889                 bench.iter(|| {
3890                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
3891                         assert!(get_route(src, &graph, dst, None, None, &[], amt, 42, &DummyLogger{}).is_ok());
3892                         idx += 1;
3893                 });
3894         }
3895
3896         #[bench]
3897         fn generate_mpp_routes(bench: &mut Bencher) {
3898                 let mut d = tests::get_route_file();
3899                 let graph = NetworkGraph::read(&mut d).unwrap();
3900
3901                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3902                 let mut path_endpoints = Vec::new();
3903                 let mut seed: usize = 0xdeadbeef;
3904                 'load_endpoints: for _ in 0..100 {
3905                         loop {
3906                                 seed *= 0xdeadbeef;
3907                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3908                                 seed *= 0xdeadbeef;
3909                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3910                                 let amt = seed as u64 % 1_000_000;
3911                                 if get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &DummyLogger{}).is_ok() {
3912                                         path_endpoints.push((src, dst, amt));
3913                                         continue 'load_endpoints;
3914                                 }
3915                         }
3916                 }
3917
3918                 // ...then benchmark finding paths between the nodes we learned.
3919                 let mut idx = 0;
3920                 bench.iter(|| {
3921                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
3922                         assert!(get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &DummyLogger{}).is_ok());
3923                         idx += 1;
3924                 });
3925         }
3926 }