_ 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 }
 148
 149 impl cmp::Ord for RouteGraphNode {
 150         fn cmp(&self, other: &RouteGraphNode) -> cmp::Ordering {
 151                 other.lowest_fee_to_peer_through_node.cmp(&self.lowest_fee_to_peer_through_node)
 152                         .then_with(|| other.pubkey.serialize().cmp(&self.pubkey.serialize()))
 153         }
 154 }
 155
 156 impl cmp::PartialOrd for RouteGraphNode {
 157         fn partial_cmp(&self, other: &RouteGraphNode) -> Option<cmp::Ordering> {
 158                 Some(self.cmp(other))
 159         }
 160 }
 161
 162 struct DummyDirectionalChannelInfo {
 163         cltv_expiry_delta: u32,
 164         htlc_minimum_msat: u64,
 165         htlc_maximum_msat: Option<u64>,
 166         fees: RoutingFees,
 167 }
 168
 169 /// It's useful to keep track of the hops associated with the fees required to use them,
 170 /// so that we can choose cheaper paths (as per Dijkstra's algorithm).
 171 /// Fee values should be updated only in the context of the whole path, see update_value_and_recompute_fees.
 172 /// These fee values are useful to choose hops as we traverse the graph "payee-to-payer".
 173 #[derive(Clone)]
 174 struct PathBuildingHop {
 175         /// Hop-specific details unrelated to the path during the routing phase,
 176         /// but rather relevant to the LN graph.
 177         route_hop: RouteHop,
 178         /// Minimal fees required to route to the source node of the current hop via any of its inbound channels.
 179         src_lowest_inbound_fees: RoutingFees,
 180         /// Fees of the channel used in this hop.
 181         channel_fees: RoutingFees,
 182         /// All the fees paid *after* this channel on the way to the destination
 183         next_hops_fee_msat: u64,
 184         /// Fee paid for the use of the current channel (see channel_fees).
 185         /// The value will be actually deducted from the counterparty balance on the previous link.
 186         hop_use_fee_msat: u64,
 187         /// Used to compare channels when choosing the for routing.
 188         /// Includes paying for the use of a hop and the following hops, as well as
 189         /// an estimated cost of reaching this hop.
 190         /// Might get stale when fees are recomputed. Primarily for internal use.
 191         total_fee_msat: u64,
 192         /// This is useful for update_value_and_recompute_fees to make sure
 193         /// we don't fall below the minimum. Should not be updated manually and
 194         /// generally should not be accessed.
 195         htlc_minimum_msat: u64,
 196 }
 197
 198 // Instantiated with a list of hops with correct data in them collected during path finding,
 199 // an instance of this struct should be further modified only via given methods.
 200 #[derive(Clone)]
 201 struct PaymentPath {
 202         hops: Vec<PathBuildingHop>,
 203 }
 204
 205 impl PaymentPath {
 206
 207         // TODO: Add a value_msat field to PaymentPath and use it instead of this function.
 208         fn get_value_msat(&self) -> u64 {
 209                 self.hops.last().unwrap().route_hop.fee_msat
 210         }
 211
 212         fn get_total_fee_paid_msat(&self) -> u64 {
 213                 if self.hops.len() < 1 {
 214                         return 0;
 215                 }
 216                 let mut result = 0;
 217                 // Can't use next_hops_fee_msat because it gets outdated.
 218                 for (i, hop) in self.hops.iter().enumerate() {
 219                         if i != self.hops.len() - 1 {
 220                                 result += hop.route_hop.fee_msat;
 221                         }
 222                 }
 223                 return result;
 224         }
 225
 226         // If the amount transferred by the path is updated, the fees should be adjusted. Any other way
 227         // to change fees may result in an inconsistency.
 228         //
 229         // Sometimes we call this function right after constructing a path which has inconsistent
 230         // (in terms of reaching htlc_minimum_msat), so that this function puts the fees in order.
 231         // In that case we call it on the "same" amount we initially allocated for this path, and which
 232         // could have been reduced on the way. In that case, there is also a risk of exceeding
 233         // available_liquidity inside this function, because the function is unaware of this bound.
 234         // In our specific recomputation cases where we never increase the value the risk is pretty low.
 235         // This function, however, does not support arbitrarily increasing the value being transferred,
 236         // and the exception will be triggered.
 237         fn update_value_and_recompute_fees(&mut self, value_msat: u64) {
 238                 assert!(value_msat <= self.hops.last().unwrap().route_hop.fee_msat);
 239
 240                 let mut total_fee_paid_msat = 0 as u64;
 241                 for i in (0..self.hops.len()).rev() {
 242                         let last_hop = i == self.hops.len() - 1;
 243
 244                         // For non-last-hop, this value will represent the fees paid on the current hop. It
 245                         // will consist of the fees for the use of the next hop, and extra fees to match
 246                         // htlc_minimum_msat of the current channel. Last hop is handled separately.
 247                         let mut cur_hop_fees_msat = 0;
 248                         if !last_hop {
 249                                 cur_hop_fees_msat = self.hops.get(i + 1).unwrap().hop_use_fee_msat;
 250                         }
 251
 252                         let mut cur_hop = self.hops.get_mut(i).unwrap();
 253                         cur_hop.next_hops_fee_msat = total_fee_paid_msat;
 254                         // Overpay in fees if we can't save these funds due to htlc_minimum_msat.
 255                         // We try to account for htlc_minimum_msat in scoring (add_entry!), so that nodes don't
 256                         // set it too high just to maliciously take more fees by exploiting this
 257                         // match htlc_minimum_msat logic.
 258                         let mut cur_hop_transferred_amount_msat = total_fee_paid_msat + value_msat;
 259                         if let Some(extra_fees_msat) = cur_hop.htlc_minimum_msat.checked_sub(cur_hop_transferred_amount_msat) {
 260                                 // Note that there is a risk that *previous hops* (those closer to us, as we go
 261                                 // payee->our_node here) would exceed their htlc_maximum_msat or available balance.
 262                                 //
 263                                 // This might make us end up with a broken route, although this should be super-rare
 264                                 // in practice, both because of how healthy channels look like, and how we pick
 265                                 // channels in add_entry.
 266                                 // Also, this can't be exploited more heavily than *announce a free path and fail
 267                                 // all payments*.
 268                                 cur_hop_transferred_amount_msat += extra_fees_msat;
 269                                 total_fee_paid_msat += extra_fees_msat;
 270                                 cur_hop_fees_msat += extra_fees_msat;
 271                         }
 272
 273                         if last_hop {
 274                                 // Final hop is a special case: it usually has just value_msat (by design), but also
 275                                 // it still could overpay for the htlc_minimum_msat.
 276                                 cur_hop.route_hop.fee_msat = cur_hop_transferred_amount_msat;
 277                         } else {
 278                                 // Propagate updated fees for the use of the channels to one hop back, where they
 279                                 // will be actually paid (fee_msat). The last hop is handled above separately.
 280                                 cur_hop.route_hop.fee_msat = cur_hop_fees_msat;
 281                         }
 282
 283                         // Fee for the use of the current hop which will be deducted on the previous hop.
 284                         // Irrelevant for the first hop, as it doesn't have the previous hop, and the use of
 285                         // this channel is free for us.
 286                         if i != 0 {
 287                                 if let Some(new_fee) = compute_fees(cur_hop_transferred_amount_msat, cur_hop.channel_fees) {
 288                                         cur_hop.hop_use_fee_msat = new_fee;
 289                                         total_fee_paid_msat += new_fee;
 290                                 } else {
 291                                         // It should not be possible because this function is called only to reduce the
 292                                         // value. In that case, compute_fee was already called with the same fees for
 293                                         // larger amount and there was no overflow.
 294                                         unreachable!();
 295                                 }
 296                         }
 297                 }
 298         }
 299 }
 300
 301 fn compute_fees(amount_msat: u64, channel_fees: RoutingFees) -> Option<u64> {
 302         let proportional_fee_millions =
 303                 amount_msat.checked_mul(channel_fees.proportional_millionths as u64);
 304         if let Some(new_fee) = proportional_fee_millions.and_then(|part| {
 305                         (channel_fees.base_msat as u64).checked_add(part / 1_000_000) }) {
 306
 307                 Some(new_fee)
 308         } else {
 309                 // This function may be (indirectly) called without any verification,
 310                 // with channel_fees provided by a caller. We should handle it gracefully.
 311                 None
 312         }
 313 }
 314
 315 /// Gets a route from us (payer) to the given target node (payee).
 316 ///
 317 /// If the payee provided features in their invoice, they should be provided via payee_features.
 318 /// Without this, MPP will only be used if the payee's features are available in the network graph.
 319 ///
 320 /// Extra routing hops between known nodes and the target will be used if they are included in
 321 /// last_hops.
 322 ///
 323 /// If some channels aren't announced, it may be useful to fill in a first_hops with the
 324 /// results from a local ChannelManager::list_usable_channels() call. If it is filled in, our
 325 /// view of our local channels (from net_graph_msg_handler) will be ignored, and only those
 326 /// in first_hops will be used.
 327 ///
 328 /// Panics if first_hops contains channels without short_channel_ids
 329 /// (ChannelManager::list_usable_channels will never include such channels).
 330 ///
 331 /// The fees on channels from us to next-hops are ignored (as they are assumed to all be
 332 /// equal), however the enabled/disabled bit on such channels as well as the
 333 /// htlc_minimum_msat/htlc_maximum_msat *are* checked as they may change based on the receiving node.
 334 pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, payee: &PublicKey, payee_features: Option<InvoiceFeatures>, first_hops: Option<&[&ChannelDetails]>,
 335         last_hops: &[&RouteHint], final_value_msat: u64, final_cltv: u32, logger: L) -> Result<Route, LightningError> where L::Target: Logger {
 336         // TODO: Obviously *only* using total fee cost sucks. We should consider weighting by
 337         // uptime/success in using a node in the past.
 338         if *payee == *our_node_id {
 339                 return Err(LightningError{err: "Cannot generate a route to ourselves".to_owned(), action: ErrorAction::IgnoreError});
 340         }
 341
 342         if final_value_msat > MAX_VALUE_MSAT {
 343                 return Err(LightningError{err: "Cannot generate a route of more value than all existing satoshis".to_owned(), action: ErrorAction::IgnoreError});
 344         }
 345
 346         if final_value_msat == 0 {
 347                 return Err(LightningError{err: "Cannot send a payment of 0 msat".to_owned(), action: ErrorAction::IgnoreError});
 348         }
 349
 350         for last_hop in last_hops {
 351                 if last_hop.src_node_id == *payee {
 352                         return Err(LightningError{err: "Last hop cannot have a payee as a source.".to_owned(), action: ErrorAction::IgnoreError});
 353                 }
 354         }
 355
 356         // The general routing idea is the following:
 357         // 1. Fill first/last hops communicated by the caller.
 358         // 2. Attempt to construct a path from payer to payee for transferring
 359         //    any ~sufficient (described later) value.
 360         //    If succeed, remember which channels were used and how much liquidity they have available,
 361         //    so that future paths don't rely on the same liquidity.
 362         // 3. Prooceed to the next step if:
 363         //    - we hit the recommended target value;
 364         //    - OR if we could not construct a new path. Any next attempt will fail too.
 365         //    Otherwise, repeat step 2.
 366         // 4. See if we managed to collect paths which aggregately are able to transfer target value
 367         //    (not recommended value). If yes, proceed. If not, fail routing.
 368         // 5. Randomly combine paths into routes having enough to fulfill the payment. (TODO: knapsack)
 369         // 6. Of all the found paths, select only those with the lowest total fee.
 370         // 7. The last path in every selected route is likely to be more than we need.
 371         //    Reduce its value-to-transfer and recompute fees.
 372         // 8. Choose the best route by the lowest total fee.
 373
 374         // As for the actual search algorithm,
 375         // we do a payee-to-payer pseudo-Dijkstra's sorting by each node's distance from the payee
 376         // plus the minimum per-HTLC fee to get from it to another node (aka "shitty pseudo-A*").
 377         //
 378         // We are not a faithful Dijkstra's implementation because we can change values which impact
 379         // earlier nodes while processing later nodes. Specifically, if we reach a channel with a lower
 380         // liquidity limit (via htlc_maximum_msat, on-chain capacity or assumed liquidity limits) then
 381         // the value we are currently attempting to send over a path, we simply reduce the value being
 382         // sent along the path for any hops after that channel. This may imply that later fees (which
 383         // we've already tabulated) are lower because a smaller value is passing through the channels
 384         // (and the proportional fee is thus lower). There isn't a trivial way to recalculate the
 385         // channels which were selected earlier (and which may still be used for other paths without a
 386         // lower liquidity limit), so we simply accept that some liquidity-limited paths may be
 387         // de-preferenced.
 388         //
 389         // One potentially problematic case for this algorithm would be if there are many
 390         // liquidity-limited paths which are liquidity-limited near the destination (ie early in our
 391         // graph walking), we may never find a path which is not liquidity-limited and has lower
 392         // proportional fee (and only lower absolute fee when considering the ultimate value sent).
 393         // Because we only consider paths with at least 5% of the total value being sent, the damage
 394         // from such a case should be limited, however this could be further reduced in the future by
 395         // calculating fees on the amount we wish to route over a path, ie ignoring the liquidity
 396         // limits for the purposes of fee calculation.
 397         //
 398         // Alternatively, we could store more detailed path information in the heap (targets, below)
 399         // and index the best-path map (dist, below) by node *and* HTLC limits, however that would blow
 400         // up the runtime significantly both algorithmically (as we'd traverse nodes multiple times)
 401         // and practically (as we would need to store dynamically-allocated path information in heap
 402         // objects, increasing malloc traffic and indirect memory access significantly). Further, the
 403         // results of such an algorithm would likely be biased towards lower-value paths.
 404         //
 405         // Further, we could return to a faithful Dijkstra's algorithm by rejecting paths with limits
 406         // outside of our current search value, running a path search more times to gather candidate
 407         // paths at different values. While this may be acceptable, further path searches may increase
 408         // runtime for little gain. Specifically, the current algorithm rather efficiently explores the
 409         // graph for candidate paths, calculating the maximum value which can realistically be sent at
 410         // the same time, remaining generic across different payment values.
 411         //
 412         // TODO: There are a few tweaks we could do, including possibly pre-calculating more stuff
 413         // to use as the A* heuristic beyond just the cost to get one node further than the current
 414         // one.
 415
 416         let dummy_directional_info = DummyDirectionalChannelInfo { // used for first_hops routes
 417                 cltv_expiry_delta: 0,
 418                 htlc_minimum_msat: 0,
 419                 htlc_maximum_msat: None,
 420                 fees: RoutingFees {
 421                         base_msat: 0,
 422                         proportional_millionths: 0,
 423                 }
 424         };
 425
 426         let mut targets = BinaryHeap::new(); //TODO: Do we care about switching to eg Fibbonaci heap?
 427         let mut dist = HashMap::with_capacity(network.get_nodes().len());
 428
 429         // When arranging a route, we select multiple paths so that we can make a multi-path payment.
 430         // Don't stop searching for paths when we think they're
 431         // sufficient to transfer a given value aggregately.
 432         // Search for higher value, so that we collect many more paths,
 433         // and then select the best combination among them.
 434         const ROUTE_CAPACITY_PROVISION_FACTOR: u64 = 3;
 435         let recommended_value_msat = final_value_msat * ROUTE_CAPACITY_PROVISION_FACTOR as u64;
 436
 437         // Allow MPP only if we have a features set from somewhere that indicates the payee supports
 438         // it. If the payee supports it they're supposed to include it in the invoice, so that should
 439         // work reliably.
 440         let allow_mpp = if let Some(features) = &payee_features {
 441                 features.supports_basic_mpp()
 442         } else if let Some(node) = network.get_nodes().get(&payee) {
 443                 if let Some(node_info) = node.announcement_info.as_ref() {
 444                         node_info.features.supports_basic_mpp()
 445                 } else { false }
 446         } else { false };
 447
 448         // Step (1).
 449         // Prepare the data we'll use for payee-to-payer search by
 450         // inserting first hops suggested by the caller as targets.
 451         // Our search will then attempt to reach them while traversing from the payee node.
 452         let mut first_hop_targets = HashMap::with_capacity(if first_hops.is_some() { first_hops.as_ref().unwrap().len() } else { 0 });
 453         if let Some(hops) = first_hops {
 454                 for chan in hops {
 455                         let short_channel_id = chan.short_channel_id.expect("first_hops should be filled in with usable channels, not pending ones");
 456                         if chan.remote_network_id == *our_node_id {
 457                                 return Err(LightningError{err: "First hop cannot have our_node_id as a destination.".to_owned(), action: ErrorAction::IgnoreError});
 458                         }
 459                         first_hop_targets.insert(chan.remote_network_id, (short_channel_id, chan.counterparty_features.clone(), chan.outbound_capacity_msat));
 460                 }
 461                 if first_hop_targets.is_empty() {
 462                         return Err(LightningError{err: "Cannot route when there are no outbound routes away from us".to_owned(), action: ErrorAction::IgnoreError});
 463                 }
 464         }
 465
 466         // We don't want multiple paths (as per MPP) share liquidity of the same channels.
 467         // This map allows paths to be aware of the channel use by other paths in the same call.
 468         // This would help to make a better path finding decisions and not "overbook" channels.
 469         // It is unaware of the directions (except for `outbound_capacity_msat` in `first_hops`).
 470         let mut bookkeeped_channels_liquidity_available_msat = HashMap::new();
 471
 472         // Keeping track of how much value we already collected across other paths. Helps to decide:
 473         // - how much a new path should be transferring (upper bound);
 474         // - whether a channel should be disregarded because
 475         //   it's available liquidity is too small comparing to how much more we need to collect;
 476         // - when we want to stop looking for new paths.
 477         let mut already_collected_value_msat = 0;
 478
 479         macro_rules! add_entry {
 480                 // Adds entry which goes from $src_node_id to $dest_node_id
 481                 // over the channel with id $chan_id with fees described in
 482                 // $directional_info.
 483                 // $next_hops_fee_msat represents the fees paid for using all the channel *after* this one,
 484                 // since that value has to be transferred over this channel.
 485                 ( $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,
 486                    $next_hops_value_contribution: expr ) => {
 487                         // Channels to self should not be used. This is more of belt-and-suspenders, because in
 488                         // practice these cases should be caught earlier:
 489                         // - for regular channels at channel announcement (TODO)
 490                         // - for first and last hops early in get_route
 491                         if $src_node_id != $dest_node_id.clone() {
 492                                 let available_liquidity_msat = bookkeeped_channels_liquidity_available_msat.entry($chan_id.clone()).or_insert_with(|| {
 493                                         let mut initial_liquidity_available_msat = None;
 494                                         if let Some(capacity_sats) = $capacity_sats {
 495                                                 initial_liquidity_available_msat = Some(capacity_sats * 1000);
 496                                         }
 497
 498                                         if let Some(htlc_maximum_msat) = $directional_info.htlc_maximum_msat {
 499                                                 if let Some(available_msat) = initial_liquidity_available_msat {
 500                                                         initial_liquidity_available_msat = Some(cmp::min(available_msat, htlc_maximum_msat));
 501                                                 } else {
 502                                                         initial_liquidity_available_msat = Some(htlc_maximum_msat);
 503                                                 }
 504                                         }
 505
 506                                         match initial_liquidity_available_msat {
 507                                                 Some(available_msat) => available_msat,
 508                                                 // We assume channels with unknown balance have
 509                                                 // a capacity of 0.0025 BTC (or 250_000 sats).
 510                                                 None => 250_000 * 1000
 511                                         }
 512                                 });
 513
 514                                 // It is tricky to substract $next_hops_fee_msat from available liquidity here.
 515                                 // It may be misleading because we might later choose to reduce the value transferred
 516                                 // over these channels, and the channel which was insufficient might become sufficient.
 517                                 // Worst case: we drop a good channel here because it can't cover the high following
 518                                 // fees caused by one expensive channel, but then this channel could have been used
 519                                 // if the amount being transferred over this path is lower.
 520                                 // We do this for now, but this is a subject for removal.
 521                                 if let Some(available_value_contribution_msat) = available_liquidity_msat.checked_sub($next_hops_fee_msat) {
 522
 523                                         // Routing Fragmentation Mitigation heuristic:
 524                                         //
 525                                         // Routing fragmentation across many payment paths increases the overall routing
 526                                         // fees as you have irreducible routing fees per-link used (`fee_base_msat`).
 527                                         // Taking too many smaller paths also increases the chance of payment failure.
 528                                         // Thus to avoid this effect, we require from our collected links to provide
 529                                         // at least a minimal contribution to the recommended value yet-to-be-fulfilled.
 530                                         //
 531                                         // This requirement is currently 5% of the remaining-to-be-collected value.
 532                                         // This means as we successfully advance in our collection,
 533                                         // the absolute liquidity contribution is lowered,
 534                                         // thus increasing the number of potential channels to be selected.
 535
 536                                         // Derive the minimal liquidity contribution with a ratio of 20 (5%, rounded up)
 537                                         // or 100% if we're not allowed to do multipath payments.
 538                                         let minimal_value_contribution_msat: u64 = if allow_mpp {
 539                                                 (recommended_value_msat - already_collected_value_msat + 19) / 20
 540                                         } else {
 541                                                 final_value_msat
 542                                         };
 543                                         // Verify the liquidity offered by this channel complies to the minimal contribution.
 544                                         let contributes_sufficient_value = available_value_contribution_msat >= minimal_value_contribution_msat;
 545
 546                                         let value_contribution_msat = cmp::min(available_value_contribution_msat, $next_hops_value_contribution);
 547                                         // Includes paying fees for the use of the following channels.
 548                                         let amount_to_transfer_over_msat: u64 = match value_contribution_msat.checked_add($next_hops_fee_msat) {
 549                                                 Some(result) => result,
 550                                                 // Can't overflow due to how the values were computed right above.
 551                                                 None => unreachable!(),
 552                                         };
 553
 554                                         // If HTLC minimum is larger than the amount we're going to transfer, we shouldn't
 555                                         // bother considering this channel.
 556                                         // Since we're choosing amount_to_transfer_over_msat as maximum possible, it can
 557                                         // be only reduced later (not increased), so this channel should just be skipped
 558                                         // as not sufficient.
 559                                         // TODO: Explore simply adding fee to hit htlc_minimum_msat
 560                                         if contributes_sufficient_value && amount_to_transfer_over_msat >= $directional_info.htlc_minimum_msat {
 561                                                 // Note that low contribution here (limited by available_liquidity_msat)
 562                                                 // might violate htlc_minimum_msat on the hops which are next along the
 563                                                 // payment path (upstream to the payee). To avoid that, we recompute path
 564                                                 // path fees knowing the final path contribution after constructing it.
 565                                                 let hm_entry = dist.entry(&$src_node_id);
 566                                                 let old_entry = hm_entry.or_insert_with(|| {
 567                                                         // If there was previously no known way to access
 568                                                         // the source node (recall it goes payee-to-payer) of $chan_id, first add
 569                                                         // a semi-dummy record just to compute the fees to reach the source node.
 570                                                         // This will affect our decision on selecting $chan_id
 571                                                         // as a way to reach the $dest_node_id.
 572                                                         let mut fee_base_msat = u32::max_value();
 573                                                         let mut fee_proportional_millionths = u32::max_value();
 574                                                         if let Some(Some(fees)) = network.get_nodes().get(&$src_node_id).map(|node| node.lowest_inbound_channel_fees) {
 575                                                                 fee_base_msat = fees.base_msat;
 576                                                                 fee_proportional_millionths = fees.proportional_millionths;
 577                                                         }
 578                                                         PathBuildingHop {
 579                                                                 route_hop: RouteHop {
 580                                                                         pubkey: $dest_node_id.clone(),
 581                                                                         node_features: NodeFeatures::empty(),
 582                                                                         short_channel_id: 0,
 583                                                                         channel_features: $chan_features.clone(),
 584                                                                         fee_msat: 0,
 585                                                                         cltv_expiry_delta: 0,
 586                                                                 },
 587                                                                 src_lowest_inbound_fees: RoutingFees {
 588                                                                         base_msat: fee_base_msat,
 589                                                                         proportional_millionths: fee_proportional_millionths,
 590                                                                 },
 591                                                                 channel_fees: $directional_info.fees,
 592                                                                 next_hops_fee_msat: u64::max_value(),
 593                                                                 hop_use_fee_msat: u64::max_value(),
 594                                                                 total_fee_msat: u64::max_value(),
 595                                                                 htlc_minimum_msat: $directional_info.htlc_minimum_msat,
 596                                                         }
 597                                                 });
 598
 599                                                 let mut hop_use_fee_msat = 0;
 600                                                 let mut total_fee_msat = $next_hops_fee_msat;
 601
 602                                                 // Ignore hop_use_fee_msat for channel-from-us as we assume all channels-from-us
 603                                                 // will have the same effective-fee
 604                                                 if $src_node_id != *our_node_id {
 605                                                         match compute_fees(amount_to_transfer_over_msat, $directional_info.fees) {
 606                                                                 // max_value means we'll always fail
 607                                                                 // the old_entry.total_fee_msat > total_fee_msat check
 608                                                                 None => total_fee_msat = u64::max_value(),
 609                                                                 Some(fee_msat) => {
 610                                                                         hop_use_fee_msat = fee_msat;
 611                                                                         total_fee_msat += hop_use_fee_msat;
 612                                                                         if let Some(prev_hop_fee_msat) = compute_fees(total_fee_msat + amount_to_transfer_over_msat,
 613                                                                                                                                                                 old_entry.src_lowest_inbound_fees) {
 614                                                                                 if let Some(incremented_total_fee_msat) = total_fee_msat.checked_add(prev_hop_fee_msat) {
 615                                                                                         total_fee_msat = incremented_total_fee_msat;
 616                                                                                 }
 617                                                                                 else {
 618                                                                                         // max_value means we'll always fail
 619                                                                                         // the old_entry.total_fee_msat > total_fee_msat check
 620                                                                                         total_fee_msat = u64::max_value();
 621                                                                                 }
 622                                                                         } else {
 623                                                                                 // max_value means we'll always fail
 624                                                                                 // the old_entry.total_fee_msat > total_fee_msat check
 625                                                                                 total_fee_msat = u64::max_value();
 626                                                                         }
 627                                                                 }
 628                                                         }
 629                                                 }
 630
 631                                                 let new_graph_node = RouteGraphNode {
 632                                                         pubkey: $src_node_id,
 633                                                         lowest_fee_to_peer_through_node: total_fee_msat,
 634                                                         lowest_fee_to_node: $next_hops_fee_msat as u64 + hop_use_fee_msat,
 635                                                         value_contribution_msat: value_contribution_msat,
 636                                                 };
 637
 638                                                 // Update the way of reaching $src_node_id with the given $chan_id (from $dest_node_id),
 639                                                 // if this way is cheaper than the already known
 640                                                 // (considering the cost to "reach" this channel from the route destination,
 641                                                 // the cost of using this channel,
 642                                                 // and the cost of routing to the source node of this channel).
 643                                                 // Also, consider that htlc_minimum_msat_difference, because we might end up
 644                                                 // paying it. Consider the following exploit:
 645                                                 // we use 2 paths to transfer 1.5 BTC. One of them is 0-fee normal 1 BTC path,
 646                                                 // and for the other one we picked a 1sat-fee path with htlc_minimum_msat of
 647                                                 // 1 BTC. Now, since the latter is more expensive, we gonna try to cut it
 648                                                 // by 0.5 BTC, but then match htlc_minimum_msat by paying a fee of 0.5 BTC
 649                                                 // to this channel.
 650                                                 // TODO: this scoring could be smarter (e.g. 0.5*htlc_minimum_msat here).
 651                                                 let mut old_cost = old_entry.total_fee_msat;
 652                                                 if let Some(increased_old_cost) = old_cost.checked_add(old_entry.htlc_minimum_msat) {
 653                                                         old_cost = increased_old_cost;
 654                                                 } else {
 655                                                         old_cost = u64::max_value();
 656                                                 }
 657
 658                                                 let mut new_cost = total_fee_msat;
 659                                                 if let Some(increased_new_cost) = new_cost.checked_add($directional_info.htlc_minimum_msat) {
 660                                                         new_cost = increased_new_cost;
 661                                                 } else {
 662                                                         new_cost = u64::max_value();
 663                                                 }
 664
 665                                                 if new_cost < old_cost {
 666                                                         targets.push(new_graph_node);
 667                                                         old_entry.next_hops_fee_msat = $next_hops_fee_msat;
 668                                                         old_entry.hop_use_fee_msat = hop_use_fee_msat;
 669                                                         old_entry.total_fee_msat = total_fee_msat;
 670                                                         old_entry.route_hop = RouteHop {
 671                                                                 pubkey: $dest_node_id.clone(),
 672                                                                 node_features: NodeFeatures::empty(),
 673                                                                 short_channel_id: $chan_id.clone(),
 674                                                                 channel_features: $chan_features.clone(),
 675                                                                 fee_msat: 0, // This value will be later filled with hop_use_fee_msat of the following channel
 676                                                                 cltv_expiry_delta: $directional_info.cltv_expiry_delta as u32,
 677                                                         };
 678                                                         old_entry.channel_fees = $directional_info.fees;
 679                                                         // It's probably fine to replace the old entry, because the new one
 680                                                         // passed the htlc_minimum-related checks above.
 681                                                         old_entry.htlc_minimum_msat = $directional_info.htlc_minimum_msat;
 682                                                 }
 683                                         }
 684                                 }
 685                         }
 686                 };
 687         }
 688
 689         // Find ways (channels with destination) to reach a given node and store them
 690         // in the corresponding data structures (routing graph etc).
 691         // $fee_to_target_msat represents how much it costs to reach to this node from the payee,
 692         // meaning how much will be paid in fees after this node (to the best of our knowledge).
 693         // This data can later be helpful to optimize routing (pay lower fees).
 694         macro_rules! add_entries_to_cheapest_to_target_node {
 695                 ( $node: expr, $node_id: expr, $fee_to_target_msat: expr, $next_hops_value_contribution: expr ) => {
 696                         if first_hops.is_some() {
 697                                 if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat)) = first_hop_targets.get(&$node_id) {
 698                                         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);
 699                                 }
 700                         }
 701
 702                         let features;
 703                         if let Some(node_info) = $node.announcement_info.as_ref() {
 704                                 features = node_info.features.clone();
 705                         } else {
 706                                 features = NodeFeatures::empty();
 707                         }
 708
 709                         if !features.requires_unknown_bits() {
 710                                 for chan_id in $node.channels.iter() {
 711                                         let chan = network.get_channels().get(chan_id).unwrap();
 712                                         if !chan.features.requires_unknown_bits() {
 713                                                 if chan.node_one == *$node_id {
 714                                                         // ie $node is one, ie next hop in A* is two, via the two_to_one channel
 715                                                         if first_hops.is_none() || chan.node_two != *our_node_id {
 716                                                                 if let Some(two_to_one) = chan.two_to_one.as_ref() {
 717                                                                         if two_to_one.enabled {
 718                                                                                 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);
 719                                                                         }
 720                                                                 }
 721                                                         }
 722                                                 } else {
 723                                                         if first_hops.is_none() || chan.node_one != *our_node_id {
 724                                                                 if let Some(one_to_two) = chan.one_to_two.as_ref() {
 725                                                                         if one_to_two.enabled {
 726                                                                                 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);
 727                                                                         }
 728                                                                 }
 729
 730                                                         }
 731                                                 }
 732                                         }
 733                                 }
 734                         }
 735                 };
 736         }
 737
 738         let mut payment_paths = Vec::<PaymentPath>::new();
 739
 740         // TODO: diversify by nodes (so that all paths aren't doomed if one node is offline).
 741         'paths_collection: loop {
 742                 // For every new path, start from scratch, except
 743                 // bookkeeped_channels_liquidity_available_msat, which will improve
 744                 // the further iterations of path finding. Also don't erase first_hop_targets.
 745                 targets.clear();
 746                 dist.clear();
 747
 748                 // If first hop is a private channel and the only way to reach the payee, this is the only
 749                 // place where it could be added.
 750                 if first_hops.is_some() {
 751                         if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat)) = first_hop_targets.get(&payee) {
 752                                 add_entry!(first_hop, *our_node_id, payee, dummy_directional_info, Some(outbound_capacity_msat / 1000), features.to_context(), 0, recommended_value_msat);
 753                         }
 754                 }
 755
 756                 // Add the payee as a target, so that the payee-to-payer
 757                 // search algorithm knows what to start with.
 758                 match network.get_nodes().get(payee) {
 759                         // The payee is not in our network graph, so nothing to add here.
 760                         // There is still a chance of reaching them via last_hops though,
 761                         // so don't yet fail the payment here.
 762                         // If not, targets.pop() will not even let us enter the loop in step 2.
 763                         None => {},
 764                         Some(node) => {
 765                                 add_entries_to_cheapest_to_target_node!(node, payee, 0, recommended_value_msat);
 766                         },
 767                 }
 768
 769                 // Step (1).
 770                 // If a caller provided us with last hops, add them to routing targets. Since this happens
 771                 // earlier than general path finding, they will be somewhat prioritized, although currently
 772                 // it matters only if the fees are exactly the same.
 773                 for hop in last_hops.iter() {
 774                         let have_hop_src_in_graph =
 775                                 if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat)) = first_hop_targets.get(&hop.src_node_id) {
 776                                         // If this hop connects to a node with which we have a direct channel, ignore
 777                                         // the network graph and add both the hop and our direct channel to
 778                                         // the candidate set.
 779                                         //
 780                                         // Currently there are no channel-context features defined, so we are a
 781                                         // bit lazy here. In the future, we should pull them out via our
 782                                         // ChannelManager, but there's no reason to waste the space until we
 783                                         // need them.
 784                                         add_entry!(first_hop, *our_node_id , hop.src_node_id, dummy_directional_info, Some(outbound_capacity_msat / 1000), features.to_context(), 0, recommended_value_msat);
 785                                         true
 786                                 } else {
 787                                         // In any other case, only add the hop if the source is in the regular network
 788                                         // graph:
 789                                         network.get_nodes().get(&hop.src_node_id).is_some()
 790                                 };
 791                         if have_hop_src_in_graph {
 792                                 // BOLT 11 doesn't allow inclusion of features for the last hop hints, which
 793                                 // really sucks, cause we're gonna need that eventually.
 794                                 let last_hop_htlc_minimum_msat: u64 = match hop.htlc_minimum_msat {
 795                                         Some(htlc_minimum_msat) => htlc_minimum_msat,
 796                                         None => 0
 797                                 };
 798                                 let directional_info = DummyDirectionalChannelInfo {
 799                                         cltv_expiry_delta: hop.cltv_expiry_delta as u32,
 800                                         htlc_minimum_msat: last_hop_htlc_minimum_msat,
 801                                         htlc_maximum_msat: hop.htlc_maximum_msat,
 802                                         fees: hop.fees,
 803                                 };
 804                                 add_entry!(hop.short_channel_id, hop.src_node_id, payee, directional_info, None::<u64>, ChannelFeatures::empty(), 0, recommended_value_msat);
 805                         }
 806                 }
 807
 808                 // At this point, targets are filled with the data from first and
 809                 // last hops communicated by the caller, and the payment receiver.
 810                 let mut found_new_path = false;
 811
 812                 // Step (2).
 813                 // If this loop terminates due the exhaustion of targets, two situations are possible:
 814                 // - not enough outgoing liquidity:
 815                 //   0 < already_collected_value_msat < final_value_msat
 816                 // - enough outgoing liquidity:
 817                 //   final_value_msat <= already_collected_value_msat < recommended_value_msat
 818                 // Both these cases (and other cases except reaching recommended_value_msat) mean that
 819                 // paths_collection will be stopped because found_new_path==false.
 820                 // This is not necessarily a routing failure.
 821                 'path_construction: while let Some(RouteGraphNode { pubkey, lowest_fee_to_node, value_contribution_msat, .. }) = targets.pop() {
 822
 823                         // Since we're going payee-to-payer, hitting our node as a target means we should stop
 824                         // traversing the graph and arrange the path out of what we found.
 825                         if pubkey == *our_node_id {
 826                                 let mut new_entry = dist.remove(&our_node_id).unwrap();
 827                                 let mut ordered_hops = vec!(new_entry.clone());
 828
 829                                 'path_walk: loop {
 830                                         if let Some(&(_, ref features, _)) = first_hop_targets.get(&ordered_hops.last().unwrap().route_hop.pubkey) {
 831                                                 ordered_hops.last_mut().unwrap().route_hop.node_features = features.to_context();
 832                                         } else if let Some(node) = network.get_nodes().get(&ordered_hops.last().unwrap().route_hop.pubkey) {
 833                                                 if let Some(node_info) = node.announcement_info.as_ref() {
 834                                                         ordered_hops.last_mut().unwrap().route_hop.node_features = node_info.features.clone();
 835                                                 } else {
 836                                                         ordered_hops.last_mut().unwrap().route_hop.node_features = NodeFeatures::empty();
 837                                                 }
 838                                         } else {
 839                                                 // We should be able to fill in features for everything except the last
 840                                                 // hop, if the last hop was provided via a BOLT 11 invoice (though we
 841                                                 // should be able to extend it further as BOLT 11 does have feature
 842                                                 // flags for the last hop node itself).
 843                                                 assert!(ordered_hops.last().unwrap().route_hop.pubkey == *payee);
 844                                         }
 845
 846                                         // Means we succesfully traversed from the payer to the payee, now
 847                                         // save this path for the payment route. Also, update the liquidity
 848                                         // remaining on the used hops, so that we take them into account
 849                                         // while looking for more paths.
 850                                         if ordered_hops.last().unwrap().route_hop.pubkey == *payee {
 851                                                 break 'path_walk;
 852                                         }
 853
 854                                         new_entry = match dist.remove(&ordered_hops.last().unwrap().route_hop.pubkey) {
 855                                                 Some(payment_hop) => payment_hop,
 856                                                 // We can't arrive at None because, if we ever add an entry to targets,
 857                                                 // we also fill in the entry in dist (see add_entry!).
 858                                                 None => unreachable!(),
 859                                         };
 860                                         // We "propagate" the fees one hop backward (topologically) here,
 861                                         // so that fees paid for a HTLC forwarding on the current channel are
 862                                         // associated with the previous channel (where they will be subtracted).
 863                                         ordered_hops.last_mut().unwrap().route_hop.fee_msat = new_entry.hop_use_fee_msat;
 864                                         ordered_hops.last_mut().unwrap().route_hop.cltv_expiry_delta = new_entry.route_hop.cltv_expiry_delta;
 865                                         ordered_hops.push(new_entry.clone());
 866                                 }
 867                                 ordered_hops.last_mut().unwrap().route_hop.fee_msat = value_contribution_msat;
 868                                 ordered_hops.last_mut().unwrap().hop_use_fee_msat = 0;
 869                                 ordered_hops.last_mut().unwrap().route_hop.cltv_expiry_delta = final_cltv;
 870
 871                                 let mut payment_path = PaymentPath {hops: ordered_hops};
 872
 873                                 // We could have possibly constructed a slightly inconsistent path: since we reduce
 874                                 // value being transferred along the way, we could have violated htlc_minimum_msat
 875                                 // on some channels we already passed (assuming dest->source direction). Here, we
 876                                 // recompute the fees again, so that if that's the case, we match the currently
 877                                 // underpaid htlc_minimum_msat with fees.
 878                                 payment_path.update_value_and_recompute_fees(value_contribution_msat);
 879
 880                                 // Since a path allows to transfer as much value as
 881                                 // the smallest channel it has ("bottleneck"), we should recompute
 882                                 // the fees so sender HTLC don't overpay fees when traversing
 883                                 // larger channels than the bottleneck. This may happen because
 884                                 // when we were selecting those channels we were not aware how much value
 885                                 // this path will transfer, and the relative fee for them
 886                                 // might have been computed considering a larger value.
 887                                 // Remember that we used these channels so that we don't rely
 888                                 // on the same liquidity in future paths.
 889                                 for payment_hop in payment_path.hops.iter() {
 890                                         let channel_liquidity_available_msat = bookkeeped_channels_liquidity_available_msat.get_mut(&payment_hop.route_hop.short_channel_id).unwrap();
 891                                         let mut spent_on_hop_msat = value_contribution_msat;
 892                                         let next_hops_fee_msat = payment_hop.next_hops_fee_msat;
 893                                         spent_on_hop_msat += next_hops_fee_msat;
 894                                         if *channel_liquidity_available_msat < spent_on_hop_msat {
 895                                                 // This should not happen because we do recompute fees right before,
 896                                                 // trying to avoid cases when a hop is not usable due to the fee situation.
 897                                                 break 'path_construction;
 898                                         }
 899                                         *channel_liquidity_available_msat -= spent_on_hop_msat;
 900                                 }
 901                                 // Track the total amount all our collected paths allow to send so that we:
 902                                 // - know when to stop looking for more paths
 903                                 // - know which of the hops are useless considering how much more sats we need
 904                                 //   (contributes_sufficient_value)
 905                                 already_collected_value_msat += value_contribution_msat;
 906
 907                                 payment_paths.push(payment_path);
 908                                 found_new_path = true;
 909                                 break 'path_construction;
 910                         }
 911
 912                         // Otherwise, since the current target node is not us,
 913                         // keep "unrolling" the payment graph from payee to payer by
 914                         // finding a way to reach the current target from the payer side.
 915                         match network.get_nodes().get(&pubkey) {
 916                                 None => {},
 917                                 Some(node) => {
 918                                         add_entries_to_cheapest_to_target_node!(node, &pubkey, lowest_fee_to_node, value_contribution_msat);
 919                                 },
 920                         }
 921                 }
 922
 923                 if !allow_mpp {
 924                         // If we don't support MPP, no use trying to gather more value ever.
 925                         break 'paths_collection;
 926                 }
 927
 928                 // Step (3).
 929                 // Stop either when recommended value is reached,
 930                 // or if during last iteration no new path was found.
 931                 // In the latter case, making another path finding attempt could not help,
 932                 // because we deterministically terminate the search due to low liquidity.
 933                 if already_collected_value_msat >= recommended_value_msat || !found_new_path {
 934                         break 'paths_collection;
 935                 }
 936         }
 937
 938         // Step (4).
 939         if payment_paths.len() == 0 {
 940                 return Err(LightningError{err: "Failed to find a path to the given destination".to_owned(), action: ErrorAction::IgnoreError});
 941         }
 942
 943         if already_collected_value_msat < final_value_msat {
 944                 return Err(LightningError{err: "Failed to find a sufficient route to the given destination".to_owned(), action: ErrorAction::IgnoreError});
 945         }
 946
 947         // Sort by total fees and take the best paths.
 948         payment_paths.sort_by_key(|path| path.get_total_fee_paid_msat());
 949         if payment_paths.len() > 50 {
 950                 payment_paths.truncate(50);
 951         }
 952
 953         // Draw multiple sufficient routes by randomly combining the selected paths.
 954         let mut drawn_routes = Vec::new();
 955         for i in 0..payment_paths.len() {
 956                 let mut cur_route = Vec::<PaymentPath>::new();
 957                 let mut aggregate_route_value_msat = 0;
 958
 959                 // Step (5).
 960                 // TODO: real random shuffle
 961                 // Currently just starts with i_th and goes up to i-1_th in a looped way.
 962                 let cur_payment_paths = [&payment_paths[i..], &payment_paths[..i]].concat();
 963
 964                 // Step (6).
 965                 for payment_path in cur_payment_paths {
 966                         cur_route.push(payment_path.clone());
 967                         aggregate_route_value_msat += payment_path.get_value_msat();
 968                         if aggregate_route_value_msat > final_value_msat {
 969                                 // Last path likely overpaid. Substract it from the most expensive
 970                                 // (in terms of proportional fee) path in this route and recompute fees.
 971                                 // This might be not the most economically efficient way, but fewer paths
 972                                 // also makes routing more reliable.
 973                                 let mut overpaid_value_msat = aggregate_route_value_msat - final_value_msat;
 974
 975                                 // First, drop some expensive low-value paths entirely if possible.
 976                                 // Sort by value so that we drop many really-low values first, since
 977                                 // fewer paths is better: the payment is less likely to fail.
 978                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
 979                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
 980                                 cur_route.sort_by_key(|path| path.get_value_msat());
 981                                 // We should make sure that at least 1 path left.
 982                                 let mut paths_left = cur_route.len();
 983                                 cur_route.retain(|path| {
 984                                         if paths_left == 1 {
 985                                                 return true
 986                                         }
 987                                         let mut keep = true;
 988                                         let path_value_msat = path.get_value_msat();
 989                                         if path_value_msat <= overpaid_value_msat {
 990                                                 keep = false;
 991                                                 overpaid_value_msat -= path_value_msat;
 992                                                 paths_left -= 1;
 993                                         }
 994                                         keep
 995                                 });
 996
 997                                 if overpaid_value_msat == 0 {
 998                                         break;
 999                                 }
1000
1001                                 assert!(cur_route.len() > 0);
1002
1003                                 // Step (7).
1004                                 // Now, substract the overpaid value from the most-expensive path.
1005                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1006                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1007                                 cur_route.sort_by_key(|path| { path.hops.iter().map(|hop| hop.channel_fees.proportional_millionths as u64).sum::<u64>() });
1008                                 let expensive_payment_path = cur_route.first_mut().unwrap();
1009                                 // We already dropped all the small channels above, meaning all the
1010                                 // remaining channels are larger than remaining overpaid_value_msat.
1011                                 // Thus, this can't be negative.
1012                                 let expensive_path_new_value_msat = expensive_payment_path.get_value_msat() - overpaid_value_msat;
1013                                 expensive_payment_path.update_value_and_recompute_fees(expensive_path_new_value_msat);
1014                                 break;
1015                         }
1016                 }
1017                 drawn_routes.push(cur_route);
1018         }
1019
1020         // Step (8).
1021         // Select the best route by lowest total fee.
1022         drawn_routes.sort_by_key(|paths| paths.iter().map(|path| path.get_total_fee_paid_msat()).sum::<u64>());
1023         let mut selected_paths = Vec::<Vec<RouteHop>>::new();
1024         for payment_path in drawn_routes.first().unwrap() {
1025                 selected_paths.push(payment_path.hops.iter().map(|payment_hop| payment_hop.route_hop.clone()).collect());
1026         }
1027
1028         if let Some(features) = &payee_features {
1029                 for path in selected_paths.iter_mut() {
1030                         path.last_mut().unwrap().node_features = features.to_context();
1031                 }
1032         }
1033
1034         let route = Route { paths: selected_paths };
1035         log_trace!(logger, "Got route: {}", log_route!(route));
1036         Ok(route)
1037 }
1038
1039 #[cfg(test)]
1040 mod tests {
1041         use routing::router::{get_route, RouteHint, RoutingFees};
1042         use routing::network_graph::{NetworkGraph, NetGraphMsgHandler};
1043         use ln::features::{ChannelFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
1044         use ln::msgs::{ErrorAction, LightningError, OptionalField, UnsignedChannelAnnouncement, ChannelAnnouncement, RoutingMessageHandler,
1045            NodeAnnouncement, UnsignedNodeAnnouncement, ChannelUpdate, UnsignedChannelUpdate};
1046         use ln::channelmanager;
1047         use util::test_utils;
1048         use util::ser::Writeable;
1049
1050         use bitcoin::hashes::sha256d::Hash as Sha256dHash;
1051         use bitcoin::hashes::Hash;
1052         use bitcoin::network::constants::Network;
1053         use bitcoin::blockdata::constants::genesis_block;
1054         use bitcoin::blockdata::script::Builder;
1055         use bitcoin::blockdata::opcodes;
1056         use bitcoin::blockdata::transaction::TxOut;
1057
1058         use hex;
1059
1060         use bitcoin::secp256k1::key::{PublicKey,SecretKey};
1061         use bitcoin::secp256k1::{Secp256k1, All};
1062
1063         use std::sync::Arc;
1064
1065         // Using the same keys for LN and BTC ids
1066         fn add_channel(net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>, secp_ctx: &Secp256k1<All>, node_1_privkey: &SecretKey,
1067            node_2_privkey: &SecretKey, features: ChannelFeatures, short_channel_id: u64) {
1068                 let node_id_1 = PublicKey::from_secret_key(&secp_ctx, node_1_privkey);
1069                 let node_id_2 = PublicKey::from_secret_key(&secp_ctx, node_2_privkey);
1070
1071                 let unsigned_announcement = UnsignedChannelAnnouncement {
1072                         features,
1073                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1074                         short_channel_id,
1075                         node_id_1,
1076                         node_id_2,
1077                         bitcoin_key_1: node_id_1,
1078                         bitcoin_key_2: node_id_2,
1079                         excess_data: Vec::new(),
1080                 };
1081
1082                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1083                 let valid_announcement = ChannelAnnouncement {
1084                         node_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1085                         node_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1086                         bitcoin_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1087                         bitcoin_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1088                         contents: unsigned_announcement.clone(),
1089                 };
1090                 match net_graph_msg_handler.handle_channel_announcement(&valid_announcement) {
1091                         Ok(res) => assert!(res),
1092                         _ => panic!()
1093                 };
1094         }
1095
1096         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) {
1097                 let msghash = hash_to_message!(&Sha256dHash::hash(&update.encode()[..])[..]);
1098                 let valid_channel_update = ChannelUpdate {
1099                         signature: secp_ctx.sign(&msghash, node_privkey),
1100                         contents: update.clone()
1101                 };
1102
1103                 match net_graph_msg_handler.handle_channel_update(&valid_channel_update) {
1104                         Ok(res) => assert!(res),
1105                         Err(_) => panic!()
1106                 };
1107         }
1108
1109         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,
1110            features: NodeFeatures, timestamp: u32) {
1111                 let node_id = PublicKey::from_secret_key(&secp_ctx, node_privkey);
1112                 let unsigned_announcement = UnsignedNodeAnnouncement {
1113                         features,
1114                         timestamp,
1115                         node_id,
1116                         rgb: [0; 3],
1117                         alias: [0; 32],
1118                         addresses: Vec::new(),
1119                         excess_address_data: Vec::new(),
1120                         excess_data: Vec::new(),
1121                 };
1122                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1123                 let valid_announcement = NodeAnnouncement {
1124                         signature: secp_ctx.sign(&msghash, node_privkey),
1125                         contents: unsigned_announcement.clone()
1126                 };
1127
1128                 match net_graph_msg_handler.handle_node_announcement(&valid_announcement) {
1129                         Ok(_) => (),
1130                         Err(_) => panic!()
1131                 };
1132         }
1133
1134         fn get_nodes(secp_ctx: &Secp256k1<All>) -> (SecretKey, PublicKey, Vec<SecretKey>, Vec<PublicKey>) {
1135                 let privkeys: Vec<SecretKey> = (2..10).map(|i| {
1136                         SecretKey::from_slice(&hex::decode(format!("{:02}", i).repeat(32)).unwrap()[..]).unwrap()
1137                 }).collect();
1138
1139                 let pubkeys = privkeys.iter().map(|secret| PublicKey::from_secret_key(&secp_ctx, secret)).collect();
1140
1141                 let our_privkey = SecretKey::from_slice(&hex::decode("01".repeat(32)).unwrap()[..]).unwrap();
1142                 let our_id = PublicKey::from_secret_key(&secp_ctx, &our_privkey);
1143
1144                 (our_privkey, our_id, privkeys, pubkeys)
1145         }
1146
1147         fn id_to_feature_flags(id: u8) -> Vec<u8> {
1148                 // Set the feature flags to the id'th odd (ie non-required) feature bit so that we can
1149                 // test for it later.
1150                 let idx = (id - 1) * 2 + 1;
1151                 if idx > 8*3 {
1152                         vec![1 << (idx - 8*3), 0, 0, 0]
1153                 } else if idx > 8*2 {
1154                         vec![1 << (idx - 8*2), 0, 0]
1155                 } else if idx > 8*1 {
1156                         vec![1 << (idx - 8*1), 0]
1157                 } else {
1158                         vec![1 << idx]
1159                 }
1160         }
1161
1162         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>) {
1163                 let secp_ctx = Secp256k1::new();
1164                 let logger = Arc::new(test_utils::TestLogger::new());
1165                 let chain_monitor = Arc::new(test_utils::TestChainSource::new(Network::Testnet));
1166                 let net_graph_msg_handler = NetGraphMsgHandler::new(genesis_block(Network::Testnet).header.block_hash(), None, Arc::clone(&logger));
1167                 // Build network from our_id to node7:
1168                 //
1169                 //        -1(1)2-  node0  -1(3)2-
1170                 //       /                       \
1171                 // our_id -1(12)2- node7 -1(13)2--- node2
1172                 //       \                       /
1173                 //        -1(2)2-  node1  -1(4)2-
1174                 //
1175                 //
1176                 // chan1  1-to-2: disabled
1177                 // chan1  2-to-1: enabled, 0 fee
1178                 //
1179                 // chan2  1-to-2: enabled, ignored fee
1180                 // chan2  2-to-1: enabled, 0 fee
1181                 //
1182                 // chan3  1-to-2: enabled, 0 fee
1183                 // chan3  2-to-1: enabled, 100 msat fee
1184                 //
1185                 // chan4  1-to-2: enabled, 100% fee
1186                 // chan4  2-to-1: enabled, 0 fee
1187                 //
1188                 // chan12 1-to-2: enabled, ignored fee
1189                 // chan12 2-to-1: enabled, 0 fee
1190                 //
1191                 // chan13 1-to-2: enabled, 200% fee
1192                 // chan13 2-to-1: enabled, 0 fee
1193                 //
1194                 //
1195                 //       -1(5)2- node3 -1(8)2--
1196                 //       |         2          |
1197                 //       |       (11)         |
1198                 //      /          1           \
1199                 // node2--1(6)2- node4 -1(9)2--- node6 (not in global route map)
1200                 //      \                      /
1201                 //       -1(7)2- node5 -1(10)2-
1202                 //
1203                 // chan5  1-to-2: enabled, 100 msat fee
1204                 // chan5  2-to-1: enabled, 0 fee
1205                 //
1206                 // chan6  1-to-2: enabled, 0 fee
1207                 // chan6  2-to-1: enabled, 0 fee
1208                 //
1209                 // chan7  1-to-2: enabled, 100% fee
1210                 // chan7  2-to-1: enabled, 0 fee
1211                 //
1212                 // chan8  1-to-2: enabled, variable fee (0 then 1000 msat)
1213                 // chan8  2-to-1: enabled, 0 fee
1214                 //
1215                 // chan9  1-to-2: enabled, 1001 msat fee
1216                 // chan9  2-to-1: enabled, 0 fee
1217                 //
1218                 // chan10 1-to-2: enabled, 0 fee
1219                 // chan10 2-to-1: enabled, 0 fee
1220                 //
1221                 // chan11 1-to-2: enabled, 0 fee
1222                 // chan11 2-to-1: enabled, 0 fee
1223
1224                 let (our_privkey, _, privkeys, _) = get_nodes(&secp_ctx);
1225
1226                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[0], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
1227                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1228                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1229                         short_channel_id: 1,
1230                         timestamp: 1,
1231                         flags: 1,
1232                         cltv_expiry_delta: 0,
1233                         htlc_minimum_msat: 0,
1234                         htlc_maximum_msat: OptionalField::Absent,
1235                         fee_base_msat: 0,
1236                         fee_proportional_millionths: 0,
1237                         excess_data: Vec::new()
1238                 });
1239
1240                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
1241
1242                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
1243                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1244                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1245                         short_channel_id: 2,
1246                         timestamp: 1,
1247                         flags: 0,
1248                         cltv_expiry_delta: u16::max_value(),
1249                         htlc_minimum_msat: 0,
1250                         htlc_maximum_msat: OptionalField::Absent,
1251                         fee_base_msat: u32::max_value(),
1252                         fee_proportional_millionths: u32::max_value(),
1253                         excess_data: Vec::new()
1254                 });
1255                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1256                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1257                         short_channel_id: 2,
1258                         timestamp: 1,
1259                         flags: 1,
1260                         cltv_expiry_delta: 0,
1261                         htlc_minimum_msat: 0,
1262                         htlc_maximum_msat: OptionalField::Absent,
1263                         fee_base_msat: 0,
1264                         fee_proportional_millionths: 0,
1265                         excess_data: Vec::new()
1266                 });
1267
1268                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
1269
1270                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[7], ChannelFeatures::from_le_bytes(id_to_feature_flags(12)), 12);
1271                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1272                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1273                         short_channel_id: 12,
1274                         timestamp: 1,
1275                         flags: 0,
1276                         cltv_expiry_delta: u16::max_value(),
1277                         htlc_minimum_msat: 0,
1278                         htlc_maximum_msat: OptionalField::Absent,
1279                         fee_base_msat: u32::max_value(),
1280                         fee_proportional_millionths: u32::max_value(),
1281                         excess_data: Vec::new()
1282                 });
1283                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1284                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1285                         short_channel_id: 12,
1286                         timestamp: 1,
1287                         flags: 1,
1288                         cltv_expiry_delta: 0,
1289                         htlc_minimum_msat: 0,
1290                         htlc_maximum_msat: OptionalField::Absent,
1291                         fee_base_msat: 0,
1292                         fee_proportional_millionths: 0,
1293                         excess_data: Vec::new()
1294                 });
1295
1296                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], NodeFeatures::from_le_bytes(id_to_feature_flags(8)), 0);
1297
1298                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
1299                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1300                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1301                         short_channel_id: 3,
1302                         timestamp: 1,
1303                         flags: 0,
1304                         cltv_expiry_delta: (3 << 8) | 1,
1305                         htlc_minimum_msat: 0,
1306                         htlc_maximum_msat: OptionalField::Absent,
1307                         fee_base_msat: 0,
1308                         fee_proportional_millionths: 0,
1309                         excess_data: Vec::new()
1310                 });
1311                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1312                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1313                         short_channel_id: 3,
1314                         timestamp: 1,
1315                         flags: 1,
1316                         cltv_expiry_delta: (3 << 8) | 2,
1317                         htlc_minimum_msat: 0,
1318                         htlc_maximum_msat: OptionalField::Absent,
1319                         fee_base_msat: 100,
1320                         fee_proportional_millionths: 0,
1321                         excess_data: Vec::new()
1322                 });
1323
1324                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
1325                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1326                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1327                         short_channel_id: 4,
1328                         timestamp: 1,
1329                         flags: 0,
1330                         cltv_expiry_delta: (4 << 8) | 1,
1331                         htlc_minimum_msat: 0,
1332                         htlc_maximum_msat: OptionalField::Absent,
1333                         fee_base_msat: 0,
1334                         fee_proportional_millionths: 1000000,
1335                         excess_data: Vec::new()
1336                 });
1337                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1338                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1339                         short_channel_id: 4,
1340                         timestamp: 1,
1341                         flags: 1,
1342                         cltv_expiry_delta: (4 << 8) | 2,
1343                         htlc_minimum_msat: 0,
1344                         htlc_maximum_msat: OptionalField::Absent,
1345                         fee_base_msat: 0,
1346                         fee_proportional_millionths: 0,
1347                         excess_data: Vec::new()
1348                 });
1349
1350                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(13)), 13);
1351                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1352                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1353                         short_channel_id: 13,
1354                         timestamp: 1,
1355                         flags: 0,
1356                         cltv_expiry_delta: (13 << 8) | 1,
1357                         htlc_minimum_msat: 0,
1358                         htlc_maximum_msat: OptionalField::Absent,
1359                         fee_base_msat: 0,
1360                         fee_proportional_millionths: 2000000,
1361                         excess_data: Vec::new()
1362                 });
1363                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1364                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1365                         short_channel_id: 13,
1366                         timestamp: 1,
1367                         flags: 1,
1368                         cltv_expiry_delta: (13 << 8) | 2,
1369                         htlc_minimum_msat: 0,
1370                         htlc_maximum_msat: OptionalField::Absent,
1371                         fee_base_msat: 0,
1372                         fee_proportional_millionths: 0,
1373                         excess_data: Vec::new()
1374                 });
1375
1376                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
1377
1378                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
1379                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1380                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1381                         short_channel_id: 6,
1382                         timestamp: 1,
1383                         flags: 0,
1384                         cltv_expiry_delta: (6 << 8) | 1,
1385                         htlc_minimum_msat: 0,
1386                         htlc_maximum_msat: OptionalField::Absent,
1387                         fee_base_msat: 0,
1388                         fee_proportional_millionths: 0,
1389                         excess_data: Vec::new()
1390                 });
1391                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1392                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1393                         short_channel_id: 6,
1394                         timestamp: 1,
1395                         flags: 1,
1396                         cltv_expiry_delta: (6 << 8) | 2,
1397                         htlc_minimum_msat: 0,
1398                         htlc_maximum_msat: OptionalField::Absent,
1399                         fee_base_msat: 0,
1400                         fee_proportional_millionths: 0,
1401                         excess_data: Vec::new(),
1402                 });
1403
1404                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(11)), 11);
1405                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1406                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1407                         short_channel_id: 11,
1408                         timestamp: 1,
1409                         flags: 0,
1410                         cltv_expiry_delta: (11 << 8) | 1,
1411                         htlc_minimum_msat: 0,
1412                         htlc_maximum_msat: OptionalField::Absent,
1413                         fee_base_msat: 0,
1414                         fee_proportional_millionths: 0,
1415                         excess_data: Vec::new()
1416                 });
1417                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
1418                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1419                         short_channel_id: 11,
1420                         timestamp: 1,
1421                         flags: 1,
1422                         cltv_expiry_delta: (11 << 8) | 2,
1423                         htlc_minimum_msat: 0,
1424                         htlc_maximum_msat: OptionalField::Absent,
1425                         fee_base_msat: 0,
1426                         fee_proportional_millionths: 0,
1427                         excess_data: Vec::new()
1428                 });
1429
1430                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(5)), 0);
1431
1432                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
1433
1434                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[5], ChannelFeatures::from_le_bytes(id_to_feature_flags(7)), 7);
1435                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1436                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1437                         short_channel_id: 7,
1438                         timestamp: 1,
1439                         flags: 0,
1440                         cltv_expiry_delta: (7 << 8) | 1,
1441                         htlc_minimum_msat: 0,
1442                         htlc_maximum_msat: OptionalField::Absent,
1443                         fee_base_msat: 0,
1444                         fee_proportional_millionths: 1000000,
1445                         excess_data: Vec::new()
1446                 });
1447                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[5], UnsignedChannelUpdate {
1448                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1449                         short_channel_id: 7,
1450                         timestamp: 1,
1451                         flags: 1,
1452                         cltv_expiry_delta: (7 << 8) | 2,
1453                         htlc_minimum_msat: 0,
1454                         htlc_maximum_msat: OptionalField::Absent,
1455                         fee_base_msat: 0,
1456                         fee_proportional_millionths: 0,
1457                         excess_data: Vec::new()
1458                 });
1459
1460                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[5], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
1461
1462                 (secp_ctx, net_graph_msg_handler, chain_monitor, logger)
1463         }
1464
1465         #[test]
1466         fn simple_route_test() {
1467                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1468                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1469
1470                 // Simple route to 2 via 1
1471
1472                 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)) {
1473                         assert_eq!(err, "Cannot send a payment of 0 msat");
1474                 } else { panic!(); }
1475
1476                 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();
1477                 assert_eq!(route.paths[0].len(), 2);
1478
1479                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
1480                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1481                 assert_eq!(route.paths[0][0].fee_msat, 100);
1482                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
1483                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
1484                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
1485
1486                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1487                 assert_eq!(route.paths[0][1].short_channel_id, 4);
1488                 assert_eq!(route.paths[0][1].fee_msat, 100);
1489                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1490                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1491                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
1492         }
1493
1494         #[test]
1495         fn invalid_first_hop_test() {
1496                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1497                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1498
1499                 // Simple route to 2 via 1
1500
1501                 let our_chans = vec![channelmanager::ChannelDetails {
1502                         channel_id: [0; 32],
1503                         short_channel_id: Some(2),
1504                         remote_network_id: our_id,
1505                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1506                         channel_value_satoshis: 100000,
1507                         user_id: 0,
1508                         outbound_capacity_msat: 100000,
1509                         inbound_capacity_msat: 100000,
1510                         is_live: true,
1511                         counterparty_forwarding_info: None,
1512                 }];
1513
1514                 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)) {
1515                         assert_eq!(err, "First hop cannot have our_node_id as a destination.");
1516                 } else { panic!(); }
1517
1518                 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();
1519                 assert_eq!(route.paths[0].len(), 2);
1520         }
1521
1522         #[test]
1523         fn htlc_minimum_test() {
1524                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1525                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1526
1527                 // Simple route to 2 via 1
1528
1529                 // Disable other paths
1530                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1531                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1532                         short_channel_id: 12,
1533                         timestamp: 2,
1534                         flags: 2, // to disable
1535                         cltv_expiry_delta: 0,
1536                         htlc_minimum_msat: 0,
1537                         htlc_maximum_msat: OptionalField::Absent,
1538                         fee_base_msat: 0,
1539                         fee_proportional_millionths: 0,
1540                         excess_data: Vec::new()
1541                 });
1542                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1543                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1544                         short_channel_id: 3,
1545                         timestamp: 2,
1546                         flags: 2, // to disable
1547                         cltv_expiry_delta: 0,
1548                         htlc_minimum_msat: 0,
1549                         htlc_maximum_msat: OptionalField::Absent,
1550                         fee_base_msat: 0,
1551                         fee_proportional_millionths: 0,
1552                         excess_data: Vec::new()
1553                 });
1554                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1555                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1556                         short_channel_id: 13,
1557                         timestamp: 2,
1558                         flags: 2, // to disable
1559                         cltv_expiry_delta: 0,
1560                         htlc_minimum_msat: 0,
1561                         htlc_maximum_msat: OptionalField::Absent,
1562                         fee_base_msat: 0,
1563                         fee_proportional_millionths: 0,
1564                         excess_data: Vec::new()
1565                 });
1566                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1567                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1568                         short_channel_id: 6,
1569                         timestamp: 2,
1570                         flags: 2, // to disable
1571                         cltv_expiry_delta: 0,
1572                         htlc_minimum_msat: 0,
1573                         htlc_maximum_msat: OptionalField::Absent,
1574                         fee_base_msat: 0,
1575                         fee_proportional_millionths: 0,
1576                         excess_data: Vec::new()
1577                 });
1578                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1579                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1580                         short_channel_id: 7,
1581                         timestamp: 2,
1582                         flags: 2, // to disable
1583                         cltv_expiry_delta: 0,
1584                         htlc_minimum_msat: 0,
1585                         htlc_maximum_msat: OptionalField::Absent,
1586                         fee_base_msat: 0,
1587                         fee_proportional_millionths: 0,
1588                         excess_data: Vec::new()
1589                 });
1590
1591                 // Check against amount_to_transfer_over_msat.
1592                 // Set minimal HTLC of 200_000_000 msat.
1593                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1594                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1595                         short_channel_id: 2,
1596                         timestamp: 3,
1597                         flags: 0,
1598                         cltv_expiry_delta: 0,
1599                         htlc_minimum_msat: 200_000_000,
1600                         htlc_maximum_msat: OptionalField::Absent,
1601                         fee_base_msat: 0,
1602                         fee_proportional_millionths: 0,
1603                         excess_data: Vec::new()
1604                 });
1605
1606                 // Second hop only allows to forward 199_999_999 at most, thus not allowing the first hop to
1607                 // be used.
1608                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1609                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1610                         short_channel_id: 4,
1611                         timestamp: 3,
1612                         flags: 0,
1613                         cltv_expiry_delta: 0,
1614                         htlc_minimum_msat: 0,
1615                         htlc_maximum_msat: OptionalField::Present(199_999_999),
1616                         fee_base_msat: 0,
1617                         fee_proportional_millionths: 0,
1618                         excess_data: Vec::new()
1619                 });
1620
1621                 // Not possible to send 199_999_999, because the minimum on channel=2 is 200_000_000.
1622                 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)) {
1623                         assert_eq!(err, "Failed to find a path to the given destination");
1624                 } else { panic!(); }
1625
1626                 // Lift the restriction on the first hop.
1627                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1628                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1629                         short_channel_id: 2,
1630                         timestamp: 4,
1631                         flags: 0,
1632                         cltv_expiry_delta: 0,
1633                         htlc_minimum_msat: 0,
1634                         htlc_maximum_msat: OptionalField::Absent,
1635                         fee_base_msat: 0,
1636                         fee_proportional_millionths: 0,
1637                         excess_data: Vec::new()
1638                 });
1639
1640                 // A payment above the minimum should pass
1641                 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();
1642                 assert_eq!(route.paths[0].len(), 2);
1643         }
1644
1645         #[test]
1646         fn htlc_minimum_overpay_test() {
1647                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1648                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1649
1650                 // A route to node#2 via two paths.
1651                 // One path allows transferring 35-40 sats, another one also allows 35-40 sats.
1652                 // Thus, they can't send 60 without overpaying.
1653                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1654                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1655                         short_channel_id: 2,
1656                         timestamp: 2,
1657                         flags: 0,
1658                         cltv_expiry_delta: 0,
1659                         htlc_minimum_msat: 35_000,
1660                         htlc_maximum_msat: OptionalField::Present(40_000),
1661                         fee_base_msat: 0,
1662                         fee_proportional_millionths: 0,
1663                         excess_data: Vec::new()
1664                 });
1665                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1666                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1667                         short_channel_id: 12,
1668                         timestamp: 3,
1669                         flags: 0,
1670                         cltv_expiry_delta: 0,
1671                         htlc_minimum_msat: 35_000,
1672                         htlc_maximum_msat: OptionalField::Present(40_000),
1673                         fee_base_msat: 0,
1674                         fee_proportional_millionths: 0,
1675                         excess_data: Vec::new()
1676                 });
1677
1678                 // Make 0 fee.
1679                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1680                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1681                         short_channel_id: 13,
1682                         timestamp: 2,
1683                         flags: 0,
1684                         cltv_expiry_delta: 0,
1685                         htlc_minimum_msat: 0,
1686                         htlc_maximum_msat: OptionalField::Absent,
1687                         fee_base_msat: 0,
1688                         fee_proportional_millionths: 0,
1689                         excess_data: Vec::new()
1690                 });
1691                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1692                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1693                         short_channel_id: 4,
1694                         timestamp: 2,
1695                         flags: 0,
1696                         cltv_expiry_delta: 0,
1697                         htlc_minimum_msat: 0,
1698                         htlc_maximum_msat: OptionalField::Absent,
1699                         fee_base_msat: 0,
1700                         fee_proportional_millionths: 0,
1701                         excess_data: Vec::new()
1702                 });
1703
1704                 // Disable other paths
1705                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1706                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1707                         short_channel_id: 1,
1708                         timestamp: 3,
1709                         flags: 2, // to disable
1710                         cltv_expiry_delta: 0,
1711                         htlc_minimum_msat: 0,
1712                         htlc_maximum_msat: OptionalField::Absent,
1713                         fee_base_msat: 0,
1714                         fee_proportional_millionths: 0,
1715                         excess_data: Vec::new()
1716                 });
1717
1718                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1719                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)).unwrap();
1720                 // Overpay fees to hit htlc_minimum_msat.
1721                 let overpaid_fees = route.paths[0][0].fee_msat + route.paths[1][0].fee_msat;
1722                 // TODO: this could be better balanced to overpay 10k and not 15k.
1723                 assert_eq!(overpaid_fees, 15_000);
1724
1725                 // Now, test that if there are 2 paths, a "cheaper" by fee path wouldn't be prioritized
1726                 // while taking even more fee to match htlc_minimum_msat.
1727                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1728                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1729                         short_channel_id: 12,
1730                         timestamp: 4,
1731                         flags: 0,
1732                         cltv_expiry_delta: 0,
1733                         htlc_minimum_msat: 65_000,
1734                         htlc_maximum_msat: OptionalField::Present(80_000),
1735                         fee_base_msat: 0,
1736                         fee_proportional_millionths: 0,
1737                         excess_data: Vec::new()
1738                 });
1739                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1740                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1741                         short_channel_id: 2,
1742                         timestamp: 3,
1743                         flags: 0,
1744                         cltv_expiry_delta: 0,
1745                         htlc_minimum_msat: 0,
1746                         htlc_maximum_msat: OptionalField::Absent,
1747                         fee_base_msat: 0,
1748                         fee_proportional_millionths: 0,
1749                         excess_data: Vec::new()
1750                 });
1751                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1752                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1753                         short_channel_id: 4,
1754                         timestamp: 4,
1755                         flags: 0,
1756                         cltv_expiry_delta: 0,
1757                         htlc_minimum_msat: 0,
1758                         htlc_maximum_msat: OptionalField::Absent,
1759                         fee_base_msat: 0,
1760                         fee_proportional_millionths: 100_000,
1761                         excess_data: Vec::new()
1762                 });
1763
1764                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1765                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)).unwrap();
1766                 // Fine to overpay for htlc_minimum_msat if it allows us to save fee.
1767                 assert_eq!(route.paths.len(), 1);
1768                 assert_eq!(route.paths[0][0].short_channel_id, 12);
1769                 let fees = route.paths[0][0].fee_msat;
1770                 assert_eq!(fees, 5_000);
1771
1772                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1773                         Some(InvoiceFeatures::known()), None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
1774                 // Not fine to overpay for htlc_minimum_msat if it requires paying more than fee on
1775                 // the other channel.
1776                 assert_eq!(route.paths.len(), 1);
1777                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1778                 let fees = route.paths[0][0].fee_msat;
1779                 assert_eq!(fees, 5_000);
1780         }
1781
1782         #[test]
1783         fn disable_channels_test() {
1784                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1785                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1786
1787                 // // Disable channels 4 and 12 by flags=2
1788                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1789                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1790                         short_channel_id: 4,
1791                         timestamp: 2,
1792                         flags: 2, // to disable
1793                         cltv_expiry_delta: 0,
1794                         htlc_minimum_msat: 0,
1795                         htlc_maximum_msat: OptionalField::Absent,
1796                         fee_base_msat: 0,
1797                         fee_proportional_millionths: 0,
1798                         excess_data: Vec::new()
1799                 });
1800                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1801                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1802                         short_channel_id: 12,
1803                         timestamp: 2,
1804                         flags: 2, // to disable
1805                         cltv_expiry_delta: 0,
1806                         htlc_minimum_msat: 0,
1807                         htlc_maximum_msat: OptionalField::Absent,
1808                         fee_base_msat: 0,
1809                         fee_proportional_millionths: 0,
1810                         excess_data: Vec::new()
1811                 });
1812
1813                 // If all the channels require some features we don't understand, route should fail
1814                 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)) {
1815                         assert_eq!(err, "Failed to find a path to the given destination");
1816                 } else { panic!(); }
1817
1818                 // If we specify a channel to node7, that overrides our local channel view and that gets used
1819                 let our_chans = vec![channelmanager::ChannelDetails {
1820                         channel_id: [0; 32],
1821                         short_channel_id: Some(42),
1822                         remote_network_id: nodes[7].clone(),
1823                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1824                         channel_value_satoshis: 0,
1825                         user_id: 0,
1826                         outbound_capacity_msat: 250_000_000,
1827                         inbound_capacity_msat: 0,
1828                         is_live: true,
1829                         counterparty_forwarding_info: None,
1830                 }];
1831                 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();
1832                 assert_eq!(route.paths[0].len(), 2);
1833
1834                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
1835                 assert_eq!(route.paths[0][0].short_channel_id, 42);
1836                 assert_eq!(route.paths[0][0].fee_msat, 200);
1837                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
1838                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
1839                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
1840
1841                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1842                 assert_eq!(route.paths[0][1].short_channel_id, 13);
1843                 assert_eq!(route.paths[0][1].fee_msat, 100);
1844                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1845                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1846                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
1847         }
1848
1849         #[test]
1850         fn disable_node_test() {
1851                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1852                 let (_, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1853
1854                 // Disable nodes 1, 2, and 8 by requiring unknown feature bits
1855                 let mut unknown_features = NodeFeatures::known();
1856                 unknown_features.set_required_unknown_bits();
1857                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], unknown_features.clone(), 1);
1858                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], unknown_features.clone(), 1);
1859                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], unknown_features.clone(), 1);
1860
1861                 // If all nodes require some features we don't understand, route should fail
1862                 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)) {
1863                         assert_eq!(err, "Failed to find a path to the given destination");
1864                 } else { panic!(); }
1865
1866                 // If we specify a channel to node7, that overrides our local channel view and that gets used
1867                 let our_chans = vec![channelmanager::ChannelDetails {
1868                         channel_id: [0; 32],
1869                         short_channel_id: Some(42),
1870                         remote_network_id: nodes[7].clone(),
1871                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1872                         channel_value_satoshis: 0,
1873                         user_id: 0,
1874                         outbound_capacity_msat: 250_000_000,
1875                         inbound_capacity_msat: 0,
1876                         is_live: true,
1877                         counterparty_forwarding_info: None,
1878                 }];
1879                 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();
1880                 assert_eq!(route.paths[0].len(), 2);
1881
1882                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
1883                 assert_eq!(route.paths[0][0].short_channel_id, 42);
1884                 assert_eq!(route.paths[0][0].fee_msat, 200);
1885                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
1886                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
1887                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
1888
1889                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1890                 assert_eq!(route.paths[0][1].short_channel_id, 13);
1891                 assert_eq!(route.paths[0][1].fee_msat, 100);
1892                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1893                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1894                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
1895
1896                 // Note that we don't test disabling node 3 and failing to route to it, as we (somewhat
1897                 // naively) assume that the user checked the feature bits on the invoice, which override
1898                 // the node_announcement.
1899         }
1900
1901         #[test]
1902         fn our_chans_test() {
1903                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1904                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1905
1906                 // Route to 1 via 2 and 3 because our channel to 1 is disabled
1907                 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();
1908                 assert_eq!(route.paths[0].len(), 3);
1909
1910                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
1911                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1912                 assert_eq!(route.paths[0][0].fee_msat, 200);
1913                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
1914                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
1915                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
1916
1917                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1918                 assert_eq!(route.paths[0][1].short_channel_id, 4);
1919                 assert_eq!(route.paths[0][1].fee_msat, 100);
1920                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (3 << 8) | 2);
1921                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1922                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
1923
1924                 assert_eq!(route.paths[0][2].pubkey, nodes[0]);
1925                 assert_eq!(route.paths[0][2].short_channel_id, 3);
1926                 assert_eq!(route.paths[0][2].fee_msat, 100);
1927                 assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
1928                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(1));
1929                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(3));
1930
1931                 // If we specify a channel to node7, that overrides our local channel view and that gets used
1932                 let our_chans = vec![channelmanager::ChannelDetails {
1933                         channel_id: [0; 32],
1934                         short_channel_id: Some(42),
1935                         remote_network_id: nodes[7].clone(),
1936                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1937                         channel_value_satoshis: 0,
1938                         user_id: 0,
1939                         outbound_capacity_msat: 250_000_000,
1940                         inbound_capacity_msat: 0,
1941                         is_live: true,
1942                         counterparty_forwarding_info: None,
1943                 }];
1944                 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();
1945                 assert_eq!(route.paths[0].len(), 2);
1946
1947                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
1948                 assert_eq!(route.paths[0][0].short_channel_id, 42);
1949                 assert_eq!(route.paths[0][0].fee_msat, 200);
1950                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
1951                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
1952                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
1953
1954                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1955                 assert_eq!(route.paths[0][1].short_channel_id, 13);
1956                 assert_eq!(route.paths[0][1].fee_msat, 100);
1957                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1958                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1959                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
1960         }
1961
1962         fn last_hops(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
1963                 let zero_fees = RoutingFees {
1964                         base_msat: 0,
1965                         proportional_millionths: 0,
1966                 };
1967                 vec!(RouteHint {
1968                         src_node_id: nodes[3].clone(),
1969                         short_channel_id: 8,
1970                         fees: zero_fees,
1971                         cltv_expiry_delta: (8 << 8) | 1,
1972                         htlc_minimum_msat: None,
1973                         htlc_maximum_msat: None,
1974                 }, RouteHint {
1975                         src_node_id: nodes[4].clone(),
1976                         short_channel_id: 9,
1977                         fees: RoutingFees {
1978                                 base_msat: 1001,
1979                                 proportional_millionths: 0,
1980                         },
1981                         cltv_expiry_delta: (9 << 8) | 1,
1982                         htlc_minimum_msat: None,
1983                         htlc_maximum_msat: None,
1984                 }, RouteHint {
1985                         src_node_id: nodes[5].clone(),
1986                         short_channel_id: 10,
1987                         fees: zero_fees,
1988                         cltv_expiry_delta: (10 << 8) | 1,
1989                         htlc_minimum_msat: None,
1990                         htlc_maximum_msat: None,
1991                 })
1992         }
1993
1994         #[test]
1995         fn last_hops_test() {
1996                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1997                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1998
1999                 // Simple test across 2, 3, 5, and 4 via a last_hop channel
2000
2001                 // First check that lst hop can't have its source as the payee.
2002                 let invalid_last_hop = RouteHint {
2003                         src_node_id: nodes[6],
2004                         short_channel_id: 8,
2005                         fees: RoutingFees {
2006                                 base_msat: 1000,
2007                                 proportional_millionths: 0,
2008                         },
2009                         cltv_expiry_delta: (8 << 8) | 1,
2010                         htlc_minimum_msat: None,
2011                         htlc_maximum_msat: None,
2012                 };
2013
2014                 let mut invalid_last_hops = last_hops(&nodes);
2015                 invalid_last_hops.push(invalid_last_hop);
2016                 {
2017                         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)) {
2018                                 assert_eq!(err, "Last hop cannot have a payee as a source.");
2019                         } else { panic!(); }
2020                 }
2021
2022                 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();
2023                 assert_eq!(route.paths[0].len(), 5);
2024
2025                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2026                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2027                 assert_eq!(route.paths[0][0].fee_msat, 100);
2028                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2029                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2030                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2031
2032                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2033                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2034                 assert_eq!(route.paths[0][1].fee_msat, 0);
2035                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2036                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2037                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2038
2039                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2040                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2041                 assert_eq!(route.paths[0][2].fee_msat, 0);
2042                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2043                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2044                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2045
2046                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2047                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2048                 assert_eq!(route.paths[0][3].fee_msat, 0);
2049                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2050                 // If we have a peer in the node map, we'll use their features here since we don't have
2051                 // a way of figuring out their features from the invoice:
2052                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2053                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2054
2055                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2056                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2057                 assert_eq!(route.paths[0][4].fee_msat, 100);
2058                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2059                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2060                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2061         }
2062
2063         #[test]
2064         fn our_chans_last_hop_connect_test() {
2065                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2066                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2067
2068                 // Simple test with outbound channel to 4 to test that last_hops and first_hops connect
2069                 let our_chans = vec![channelmanager::ChannelDetails {
2070                         channel_id: [0; 32],
2071                         short_channel_id: Some(42),
2072                         remote_network_id: nodes[3].clone(),
2073                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2074                         channel_value_satoshis: 0,
2075                         user_id: 0,
2076                         outbound_capacity_msat: 250_000_000,
2077                         inbound_capacity_msat: 0,
2078                         is_live: true,
2079                         counterparty_forwarding_info: None,
2080                 }];
2081                 let mut last_hops = last_hops(&nodes);
2082                 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();
2083                 assert_eq!(route.paths[0].len(), 2);
2084
2085                 assert_eq!(route.paths[0][0].pubkey, nodes[3]);
2086                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2087                 assert_eq!(route.paths[0][0].fee_msat, 0);
2088                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2089                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2090                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2091
2092                 assert_eq!(route.paths[0][1].pubkey, nodes[6]);
2093                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2094                 assert_eq!(route.paths[0][1].fee_msat, 100);
2095                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2096                 assert_eq!(route.paths[0][1].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2097                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2098
2099                 last_hops[0].fees.base_msat = 1000;
2100
2101                 // Revert to via 6 as the fee on 8 goes up
2102                 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();
2103                 assert_eq!(route.paths[0].len(), 4);
2104
2105                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2106                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2107                 assert_eq!(route.paths[0][0].fee_msat, 200); // fee increased as its % of value transferred across node
2108                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2109                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2110                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2111
2112                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2113                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2114                 assert_eq!(route.paths[0][1].fee_msat, 100);
2115                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (7 << 8) | 1);
2116                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2117                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2118
2119                 assert_eq!(route.paths[0][2].pubkey, nodes[5]);
2120                 assert_eq!(route.paths[0][2].short_channel_id, 7);
2121                 assert_eq!(route.paths[0][2].fee_msat, 0);
2122                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (10 << 8) | 1);
2123                 // If we have a peer in the node map, we'll use their features here since we don't have
2124                 // a way of figuring out their features from the invoice:
2125                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
2126                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(7));
2127
2128                 assert_eq!(route.paths[0][3].pubkey, nodes[6]);
2129                 assert_eq!(route.paths[0][3].short_channel_id, 10);
2130                 assert_eq!(route.paths[0][3].fee_msat, 100);
2131                 assert_eq!(route.paths[0][3].cltv_expiry_delta, 42);
2132                 assert_eq!(route.paths[0][3].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2133                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2134
2135                 // ...but still use 8 for larger payments as 6 has a variable feerate
2136                 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();
2137                 assert_eq!(route.paths[0].len(), 5);
2138
2139                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2140                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2141                 assert_eq!(route.paths[0][0].fee_msat, 3000);
2142                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2143                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2144                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2145
2146                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2147                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2148                 assert_eq!(route.paths[0][1].fee_msat, 0);
2149                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2150                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2151                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2152
2153                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2154                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2155                 assert_eq!(route.paths[0][2].fee_msat, 0);
2156                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2157                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2158                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2159
2160                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2161                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2162                 assert_eq!(route.paths[0][3].fee_msat, 1000);
2163                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2164                 // If we have a peer in the node map, we'll use their features here since we don't have
2165                 // a way of figuring out their features from the invoice:
2166                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2167                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2168
2169                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2170                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2171                 assert_eq!(route.paths[0][4].fee_msat, 2000);
2172                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2173                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2174                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2175         }
2176
2177         #[test]
2178         fn unannounced_path_test() {
2179                 // We should be able to send a payment to a destination without any help of a routing graph
2180                 // if we have a channel with a common counterparty that appears in the first and last hop
2181                 // hints.
2182                 let source_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 41).repeat(32)).unwrap()[..]).unwrap());
2183                 let middle_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 42).repeat(32)).unwrap()[..]).unwrap());
2184                 let target_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 43).repeat(32)).unwrap()[..]).unwrap());
2185
2186                 // If we specify a channel to a middle hop, that overrides our local channel view and that gets used
2187                 let last_hops = vec![RouteHint {
2188                         src_node_id: middle_node_id,
2189                         short_channel_id: 8,
2190                         fees: RoutingFees {
2191                                 base_msat: 1000,
2192                                 proportional_millionths: 0,
2193                         },
2194                         cltv_expiry_delta: (8 << 8) | 1,
2195                         htlc_minimum_msat: None,
2196                         htlc_maximum_msat: None,
2197                 }];
2198                 let our_chans = vec![channelmanager::ChannelDetails {
2199                         channel_id: [0; 32],
2200                         short_channel_id: Some(42),
2201                         remote_network_id: middle_node_id,
2202                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2203                         channel_value_satoshis: 100000,
2204                         user_id: 0,
2205                         outbound_capacity_msat: 100000,
2206                         inbound_capacity_msat: 100000,
2207                         is_live: true,
2208                         counterparty_forwarding_info: None,
2209                 }];
2210                 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();
2211
2212                 assert_eq!(route.paths[0].len(), 2);
2213
2214                 assert_eq!(route.paths[0][0].pubkey, middle_node_id);
2215                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2216                 assert_eq!(route.paths[0][0].fee_msat, 1000);
2217                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2218                 assert_eq!(route.paths[0][0].node_features.le_flags(), &[0b11]);
2219                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2220
2221                 assert_eq!(route.paths[0][1].pubkey, target_node_id);
2222                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2223                 assert_eq!(route.paths[0][1].fee_msat, 100);
2224                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2225                 assert_eq!(route.paths[0][1].node_features.le_flags(), &[0; 0]); // We dont pass flags in from invoices yet
2226                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2227         }
2228
2229         #[test]
2230         fn available_amount_while_routing_test() {
2231                 // Tests whether we choose the correct available channel amount while routing.
2232
2233                 let (secp_ctx, mut net_graph_msg_handler, chain_monitor, logger) = build_graph();
2234                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2235
2236                 // We will use a simple single-path route from
2237                 // our node to node2 via node0: channels {1, 3}.
2238
2239                 // First disable all other paths.
2240                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2241                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2242                         short_channel_id: 2,
2243                         timestamp: 2,
2244                         flags: 2,
2245                         cltv_expiry_delta: 0,
2246                         htlc_minimum_msat: 0,
2247                         htlc_maximum_msat: OptionalField::Present(100_000),
2248                         fee_base_msat: 0,
2249                         fee_proportional_millionths: 0,
2250                         excess_data: Vec::new()
2251                 });
2252                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2253                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2254                         short_channel_id: 12,
2255                         timestamp: 2,
2256                         flags: 2,
2257                         cltv_expiry_delta: 0,
2258                         htlc_minimum_msat: 0,
2259                         htlc_maximum_msat: OptionalField::Present(100_000),
2260                         fee_base_msat: 0,
2261                         fee_proportional_millionths: 0,
2262                         excess_data: Vec::new()
2263                 });
2264
2265                 // Make the first channel (#1) very permissive,
2266                 // and we will be testing all limits on the second channel.
2267                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2268                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2269                         short_channel_id: 1,
2270                         timestamp: 2,
2271                         flags: 0,
2272                         cltv_expiry_delta: 0,
2273                         htlc_minimum_msat: 0,
2274                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2275                         fee_base_msat: 0,
2276                         fee_proportional_millionths: 0,
2277                         excess_data: Vec::new()
2278                 });
2279
2280                 // First, let's see if routing works if we have absolutely no idea about the available amount.
2281                 // In this case, it should be set to 250_000 sats.
2282                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2283                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2284                         short_channel_id: 3,
2285                         timestamp: 2,
2286                         flags: 0,
2287                         cltv_expiry_delta: 0,
2288                         htlc_minimum_msat: 0,
2289                         htlc_maximum_msat: OptionalField::Absent,
2290                         fee_base_msat: 0,
2291                         fee_proportional_millionths: 0,
2292                         excess_data: Vec::new()
2293                 });
2294
2295                 {
2296                         // Attempt to route more than available results in a failure.
2297                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2298                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000_001, 42, Arc::clone(&logger)) {
2299                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2300                         } else { panic!(); }
2301                 }
2302
2303                 {
2304                         // Now, attempt to route an exact amount we have should be fine.
2305                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2306                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000_000, 42, Arc::clone(&logger)).unwrap();
2307                         assert_eq!(route.paths.len(), 1);
2308                         let path = route.paths.last().unwrap();
2309                         assert_eq!(path.len(), 2);
2310                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2311                         assert_eq!(path.last().unwrap().fee_msat, 250_000_000);
2312                 }
2313
2314                 // Check that setting outbound_capacity_msat in first_hops limits the channels.
2315                 // Disable channel #1 and use another first hop.
2316                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2317                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2318                         short_channel_id: 1,
2319                         timestamp: 3,
2320                         flags: 2,
2321                         cltv_expiry_delta: 0,
2322                         htlc_minimum_msat: 0,
2323                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2324                         fee_base_msat: 0,
2325                         fee_proportional_millionths: 0,
2326                         excess_data: Vec::new()
2327                 });
2328
2329                 // Now, limit the first_hop by the outbound_capacity_msat of 200_000 sats.
2330                 let our_chans = vec![channelmanager::ChannelDetails {
2331                         channel_id: [0; 32],
2332                         short_channel_id: Some(42),
2333                         remote_network_id: nodes[0].clone(),
2334                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2335                         channel_value_satoshis: 0,
2336                         user_id: 0,
2337                         outbound_capacity_msat: 200_000_000,
2338                         inbound_capacity_msat: 0,
2339                         is_live: true,
2340                         counterparty_forwarding_info: None,
2341                 }];
2342
2343                 {
2344                         // Attempt to route more than available results in a failure.
2345                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2346                                         Some(InvoiceFeatures::known()), Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_001, 42, Arc::clone(&logger)) {
2347                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2348                         } else { panic!(); }
2349                 }
2350
2351                 {
2352                         // Now, attempt to route an exact amount we have should be fine.
2353                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2354                                 Some(InvoiceFeatures::known()), Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_000, 42, Arc::clone(&logger)).unwrap();
2355                         assert_eq!(route.paths.len(), 1);
2356                         let path = route.paths.last().unwrap();
2357                         assert_eq!(path.len(), 2);
2358                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2359                         assert_eq!(path.last().unwrap().fee_msat, 200_000_000);
2360                 }
2361
2362                 // Enable channel #1 back.
2363                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2364                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2365                         short_channel_id: 1,
2366                         timestamp: 4,
2367                         flags: 0,
2368                         cltv_expiry_delta: 0,
2369                         htlc_minimum_msat: 0,
2370                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2371                         fee_base_msat: 0,
2372                         fee_proportional_millionths: 0,
2373                         excess_data: Vec::new()
2374                 });
2375
2376
2377                 // Now let's see if routing works if we know only htlc_maximum_msat.
2378                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2379                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2380                         short_channel_id: 3,
2381                         timestamp: 3,
2382                         flags: 0,
2383                         cltv_expiry_delta: 0,
2384                         htlc_minimum_msat: 0,
2385                         htlc_maximum_msat: OptionalField::Present(15_000),
2386                         fee_base_msat: 0,
2387                         fee_proportional_millionths: 0,
2388                         excess_data: Vec::new()
2389                 });
2390
2391                 {
2392                         // Attempt to route more than available results in a failure.
2393                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2394                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 15_001, 42, Arc::clone(&logger)) {
2395                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2396                         } else { panic!(); }
2397                 }
2398
2399                 {
2400                         // Now, attempt to route an exact amount we have should be fine.
2401                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2402                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 15_000, 42, Arc::clone(&logger)).unwrap();
2403                         assert_eq!(route.paths.len(), 1);
2404                         let path = route.paths.last().unwrap();
2405                         assert_eq!(path.len(), 2);
2406                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2407                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
2408                 }
2409
2410                 // Now let's see if routing works if we know only capacity from the UTXO.
2411
2412                 // We can't change UTXO capacity on the fly, so we'll disable
2413                 // the existing channel and add another one with the capacity we need.
2414                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2415                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2416                         short_channel_id: 3,
2417                         timestamp: 4,
2418                         flags: 2,
2419                         cltv_expiry_delta: 0,
2420                         htlc_minimum_msat: 0,
2421                         htlc_maximum_msat: OptionalField::Absent,
2422                         fee_base_msat: 0,
2423                         fee_proportional_millionths: 0,
2424                         excess_data: Vec::new()
2425                 });
2426
2427                 let good_script = Builder::new().push_opcode(opcodes::all::OP_PUSHNUM_2)
2428                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[0]).serialize())
2429                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[2]).serialize())
2430                 .push_opcode(opcodes::all::OP_PUSHNUM_2)
2431                 .push_opcode(opcodes::all::OP_CHECKMULTISIG).into_script().to_v0_p2wsh();
2432
2433                 *chain_monitor.utxo_ret.lock().unwrap() = Ok(TxOut { value: 15, script_pubkey: good_script.clone() });
2434                 net_graph_msg_handler.add_chain_access(Some(chain_monitor));
2435
2436                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 333);
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: 333,
2440                         timestamp: 1,
2441                         flags: 0,
2442                         cltv_expiry_delta: (3 << 8) | 1,
2443                         htlc_minimum_msat: 0,
2444                         htlc_maximum_msat: OptionalField::Absent,
2445                         fee_base_msat: 0,
2446                         fee_proportional_millionths: 0,
2447                         excess_data: Vec::new()
2448                 });
2449                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2450                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2451                         short_channel_id: 333,
2452                         timestamp: 1,
2453                         flags: 1,
2454                         cltv_expiry_delta: (3 << 8) | 2,
2455                         htlc_minimum_msat: 0,
2456                         htlc_maximum_msat: OptionalField::Absent,
2457                         fee_base_msat: 100,
2458                         fee_proportional_millionths: 0,
2459                         excess_data: Vec::new()
2460                 });
2461
2462                 {
2463                         // Attempt to route more than available results in a failure.
2464                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2465                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 15_001, 42, Arc::clone(&logger)) {
2466                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2467                         } else { panic!(); }
2468                 }
2469
2470                 {
2471                         // Now, attempt to route an exact amount we have should be fine.
2472                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2473                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 15_000, 42, Arc::clone(&logger)).unwrap();
2474                         assert_eq!(route.paths.len(), 1);
2475                         let path = route.paths.last().unwrap();
2476                         assert_eq!(path.len(), 2);
2477                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2478                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
2479                 }
2480
2481                 // Now let's see if routing chooses htlc_maximum_msat over UTXO capacity.
2482                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2483                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2484                         short_channel_id: 333,
2485                         timestamp: 6,
2486                         flags: 0,
2487                         cltv_expiry_delta: 0,
2488                         htlc_minimum_msat: 0,
2489                         htlc_maximum_msat: OptionalField::Present(10_000),
2490                         fee_base_msat: 0,
2491                         fee_proportional_millionths: 0,
2492                         excess_data: Vec::new()
2493                 });
2494
2495                 {
2496                         // Attempt to route more than available results in a failure.
2497                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2498                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 10_001, 42, Arc::clone(&logger)) {
2499                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2500                         } else { panic!(); }
2501                 }
2502
2503                 {
2504                         // Now, attempt to route an exact amount we have should be fine.
2505                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2506                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 10_000, 42, Arc::clone(&logger)).unwrap();
2507                         assert_eq!(route.paths.len(), 1);
2508                         let path = route.paths.last().unwrap();
2509                         assert_eq!(path.len(), 2);
2510                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2511                         assert_eq!(path.last().unwrap().fee_msat, 10_000);
2512                 }
2513         }
2514
2515         #[test]
2516         fn available_liquidity_last_hop_test() {
2517                 // Check that available liquidity properly limits the path even when only
2518                 // one of the latter hops is limited.
2519                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2520                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2521
2522                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
2523                 // {12, 13, 11} have the capacities of 100, {6} has a capacity of 50.
2524                 // Total capacity: 50 sats.
2525
2526                 // Disable other potential paths.
2527                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2528                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2529                         short_channel_id: 2,
2530                         timestamp: 2,
2531                         flags: 2,
2532                         cltv_expiry_delta: 0,
2533                         htlc_minimum_msat: 0,
2534                         htlc_maximum_msat: OptionalField::Present(100_000),
2535                         fee_base_msat: 0,
2536                         fee_proportional_millionths: 0,
2537                         excess_data: Vec::new()
2538                 });
2539                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2540                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2541                         short_channel_id: 7,
2542                         timestamp: 2,
2543                         flags: 2,
2544                         cltv_expiry_delta: 0,
2545                         htlc_minimum_msat: 0,
2546                         htlc_maximum_msat: OptionalField::Present(100_000),
2547                         fee_base_msat: 0,
2548                         fee_proportional_millionths: 0,
2549                         excess_data: Vec::new()
2550                 });
2551
2552                 // Limit capacities
2553
2554                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2555                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2556                         short_channel_id: 12,
2557                         timestamp: 2,
2558                         flags: 0,
2559                         cltv_expiry_delta: 0,
2560                         htlc_minimum_msat: 0,
2561                         htlc_maximum_msat: OptionalField::Present(100_000),
2562                         fee_base_msat: 0,
2563                         fee_proportional_millionths: 0,
2564                         excess_data: Vec::new()
2565                 });
2566                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2567                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2568                         short_channel_id: 13,
2569                         timestamp: 2,
2570                         flags: 0,
2571                         cltv_expiry_delta: 0,
2572                         htlc_minimum_msat: 0,
2573                         htlc_maximum_msat: OptionalField::Present(100_000),
2574                         fee_base_msat: 0,
2575                         fee_proportional_millionths: 0,
2576                         excess_data: Vec::new()
2577                 });
2578
2579                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2580                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2581                         short_channel_id: 6,
2582                         timestamp: 2,
2583                         flags: 0,
2584                         cltv_expiry_delta: 0,
2585                         htlc_minimum_msat: 0,
2586                         htlc_maximum_msat: OptionalField::Present(50_000),
2587                         fee_base_msat: 0,
2588                         fee_proportional_millionths: 0,
2589                         excess_data: Vec::new()
2590                 });
2591                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
2592                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2593                         short_channel_id: 11,
2594                         timestamp: 2,
2595                         flags: 0,
2596                         cltv_expiry_delta: 0,
2597                         htlc_minimum_msat: 0,
2598                         htlc_maximum_msat: OptionalField::Present(100_000),
2599                         fee_base_msat: 0,
2600                         fee_proportional_millionths: 0,
2601                         excess_data: Vec::new()
2602                 });
2603                 {
2604                         // Attempt to route more than available results in a failure.
2605                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2606                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)) {
2607                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2608                         } else { panic!(); }
2609                 }
2610
2611                 {
2612                         // Now, attempt to route 49 sats (just a bit below the capacity).
2613                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2614                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 49_000, 42, Arc::clone(&logger)).unwrap();
2615                         assert_eq!(route.paths.len(), 1);
2616                         let mut total_amount_paid_msat = 0;
2617                         for path in &route.paths {
2618                                 assert_eq!(path.len(), 4);
2619                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
2620                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2621                         }
2622                         assert_eq!(total_amount_paid_msat, 49_000);
2623                 }
2624
2625                 {
2626                         // Attempt to route an exact amount is also fine
2627                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2628                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
2629                         assert_eq!(route.paths.len(), 1);
2630                         let mut total_amount_paid_msat = 0;
2631                         for path in &route.paths {
2632                                 assert_eq!(path.len(), 4);
2633                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
2634                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2635                         }
2636                         assert_eq!(total_amount_paid_msat, 50_000);
2637                 }
2638         }
2639
2640         #[test]
2641         fn ignore_fee_first_hop_test() {
2642                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2643                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2644
2645                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
2646                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2647                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2648                         short_channel_id: 1,
2649                         timestamp: 2,
2650                         flags: 0,
2651                         cltv_expiry_delta: 0,
2652                         htlc_minimum_msat: 0,
2653                         htlc_maximum_msat: OptionalField::Present(100_000),
2654                         fee_base_msat: 1_000_000,
2655                         fee_proportional_millionths: 0,
2656                         excess_data: Vec::new()
2657                 });
2658                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2659                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2660                         short_channel_id: 3,
2661                         timestamp: 2,
2662                         flags: 0,
2663                         cltv_expiry_delta: 0,
2664                         htlc_minimum_msat: 0,
2665                         htlc_maximum_msat: OptionalField::Present(50_000),
2666                         fee_base_msat: 0,
2667                         fee_proportional_millionths: 0,
2668                         excess_data: Vec::new()
2669                 });
2670
2671                 {
2672                         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();
2673                         assert_eq!(route.paths.len(), 1);
2674                         let mut total_amount_paid_msat = 0;
2675                         for path in &route.paths {
2676                                 assert_eq!(path.len(), 2);
2677                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2678                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2679                         }
2680                         assert_eq!(total_amount_paid_msat, 50_000);
2681                 }
2682         }
2683
2684         #[test]
2685         fn simple_mpp_route_test() {
2686                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2687                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2688
2689                 // We need a route consisting of 3 paths:
2690                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
2691                 // To achieve this, the amount being transferred should be around
2692                 // the total capacity of these 3 paths.
2693
2694                 // First, we set limits on these (previously unlimited) channels.
2695                 // Their aggregate capacity will be 50 + 60 + 180 = 290 sats.
2696
2697                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
2698                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2699                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2700                         short_channel_id: 1,
2701                         timestamp: 2,
2702                         flags: 0,
2703                         cltv_expiry_delta: 0,
2704                         htlc_minimum_msat: 0,
2705                         htlc_maximum_msat: OptionalField::Present(100_000),
2706                         fee_base_msat: 0,
2707                         fee_proportional_millionths: 0,
2708                         excess_data: Vec::new()
2709                 });
2710                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2711                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2712                         short_channel_id: 3,
2713                         timestamp: 2,
2714                         flags: 0,
2715                         cltv_expiry_delta: 0,
2716                         htlc_minimum_msat: 0,
2717                         htlc_maximum_msat: OptionalField::Present(50_000),
2718                         fee_base_msat: 0,
2719                         fee_proportional_millionths: 0,
2720                         excess_data: Vec::new()
2721                 });
2722
2723                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats
2724                 // (total limit 60).
2725                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2726                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2727                         short_channel_id: 12,
2728                         timestamp: 2,
2729                         flags: 0,
2730                         cltv_expiry_delta: 0,
2731                         htlc_minimum_msat: 0,
2732                         htlc_maximum_msat: OptionalField::Present(60_000),
2733                         fee_base_msat: 0,
2734                         fee_proportional_millionths: 0,
2735                         excess_data: Vec::new()
2736                 });
2737                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2738                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2739                         short_channel_id: 13,
2740                         timestamp: 2,
2741                         flags: 0,
2742                         cltv_expiry_delta: 0,
2743                         htlc_minimum_msat: 0,
2744                         htlc_maximum_msat: OptionalField::Present(60_000),
2745                         fee_base_msat: 0,
2746                         fee_proportional_millionths: 0,
2747                         excess_data: Vec::new()
2748                 });
2749
2750                 // Path via node1 is channels {2, 4}. Limit them to 200 and 180 sats
2751                 // (total capacity 180 sats).
2752                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2753                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2754                         short_channel_id: 2,
2755                         timestamp: 2,
2756                         flags: 0,
2757                         cltv_expiry_delta: 0,
2758                         htlc_minimum_msat: 0,
2759                         htlc_maximum_msat: OptionalField::Present(200_000),
2760                         fee_base_msat: 0,
2761                         fee_proportional_millionths: 0,
2762                         excess_data: Vec::new()
2763                 });
2764                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2765                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2766                         short_channel_id: 4,
2767                         timestamp: 2,
2768                         flags: 0,
2769                         cltv_expiry_delta: 0,
2770                         htlc_minimum_msat: 0,
2771                         htlc_maximum_msat: OptionalField::Present(180_000),
2772                         fee_base_msat: 0,
2773                         fee_proportional_millionths: 0,
2774                         excess_data: Vec::new()
2775                 });
2776
2777                 {
2778                         // Attempt to route more than available results in a failure.
2779                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(),
2780                                         &nodes[2], Some(InvoiceFeatures::known()), None, &Vec::new(), 300_000, 42, Arc::clone(&logger)) {
2781                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2782                         } else { panic!(); }
2783                 }
2784
2785                 {
2786                         // Now, attempt to route 250 sats (just a bit below the capacity).
2787                         // Our algorithm should provide us with these 3 paths.
2788                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2789                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000, 42, Arc::clone(&logger)).unwrap();
2790                         assert_eq!(route.paths.len(), 3);
2791                         let mut total_amount_paid_msat = 0;
2792                         for path in &route.paths {
2793                                 assert_eq!(path.len(), 2);
2794                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2795                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2796                         }
2797                         assert_eq!(total_amount_paid_msat, 250_000);
2798                 }
2799
2800                 {
2801                         // Attempt to route an exact amount is also fine
2802                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2803                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 290_000, 42, Arc::clone(&logger)).unwrap();
2804                         assert_eq!(route.paths.len(), 3);
2805                         let mut total_amount_paid_msat = 0;
2806                         for path in &route.paths {
2807                                 assert_eq!(path.len(), 2);
2808                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2809                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2810                         }
2811                         assert_eq!(total_amount_paid_msat, 290_000);
2812                 }
2813         }
2814
2815         #[test]
2816         fn long_mpp_route_test() {
2817                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2818                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2819
2820                 // We need a route consisting of 3 paths:
2821                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
2822                 // Note that these paths overlap (channels 5, 12, 13).
2823                 // We will route 300 sats.
2824                 // Each path will have 100 sats capacity, those channels which
2825                 // are used twice will have 200 sats capacity.
2826
2827                 // Disable other potential paths.
2828                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2829                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2830                         short_channel_id: 2,
2831                         timestamp: 2,
2832                         flags: 2,
2833                         cltv_expiry_delta: 0,
2834                         htlc_minimum_msat: 0,
2835                         htlc_maximum_msat: OptionalField::Present(100_000),
2836                         fee_base_msat: 0,
2837                         fee_proportional_millionths: 0,
2838                         excess_data: Vec::new()
2839                 });
2840                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2841                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2842                         short_channel_id: 7,
2843                         timestamp: 2,
2844                         flags: 2,
2845                         cltv_expiry_delta: 0,
2846                         htlc_minimum_msat: 0,
2847                         htlc_maximum_msat: OptionalField::Present(100_000),
2848                         fee_base_msat: 0,
2849                         fee_proportional_millionths: 0,
2850                         excess_data: Vec::new()
2851                 });
2852
2853                 // Path via {node0, node2} is channels {1, 3, 5}.
2854                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2855                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2856                         short_channel_id: 1,
2857                         timestamp: 2,
2858                         flags: 0,
2859                         cltv_expiry_delta: 0,
2860                         htlc_minimum_msat: 0,
2861                         htlc_maximum_msat: OptionalField::Present(100_000),
2862                         fee_base_msat: 0,
2863                         fee_proportional_millionths: 0,
2864                         excess_data: Vec::new()
2865                 });
2866                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2867                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2868                         short_channel_id: 3,
2869                         timestamp: 2,
2870                         flags: 0,
2871                         cltv_expiry_delta: 0,
2872                         htlc_minimum_msat: 0,
2873                         htlc_maximum_msat: OptionalField::Present(100_000),
2874                         fee_base_msat: 0,
2875                         fee_proportional_millionths: 0,
2876                         excess_data: Vec::new()
2877                 });
2878
2879                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
2880                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
2881                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2882                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2883                         short_channel_id: 5,
2884                         timestamp: 2,
2885                         flags: 0,
2886                         cltv_expiry_delta: 0,
2887                         htlc_minimum_msat: 0,
2888                         htlc_maximum_msat: OptionalField::Present(200_000),
2889                         fee_base_msat: 0,
2890                         fee_proportional_millionths: 0,
2891                         excess_data: Vec::new()
2892                 });
2893
2894                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
2895                 // Add 100 sats to the capacities of {12, 13}, because these channels
2896                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
2897                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2898                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2899                         short_channel_id: 12,
2900                         timestamp: 2,
2901                         flags: 0,
2902                         cltv_expiry_delta: 0,
2903                         htlc_minimum_msat: 0,
2904                         htlc_maximum_msat: OptionalField::Present(200_000),
2905                         fee_base_msat: 0,
2906                         fee_proportional_millionths: 0,
2907                         excess_data: Vec::new()
2908                 });
2909                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2910                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2911                         short_channel_id: 13,
2912                         timestamp: 2,
2913                         flags: 0,
2914                         cltv_expiry_delta: 0,
2915                         htlc_minimum_msat: 0,
2916                         htlc_maximum_msat: OptionalField::Present(200_000),
2917                         fee_base_msat: 0,
2918                         fee_proportional_millionths: 0,
2919                         excess_data: Vec::new()
2920                 });
2921
2922                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2923                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2924                         short_channel_id: 6,
2925                         timestamp: 2,
2926                         flags: 0,
2927                         cltv_expiry_delta: 0,
2928                         htlc_minimum_msat: 0,
2929                         htlc_maximum_msat: OptionalField::Present(100_000),
2930                         fee_base_msat: 0,
2931                         fee_proportional_millionths: 0,
2932                         excess_data: Vec::new()
2933                 });
2934                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
2935                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2936                         short_channel_id: 11,
2937                         timestamp: 2,
2938                         flags: 0,
2939                         cltv_expiry_delta: 0,
2940                         htlc_minimum_msat: 0,
2941                         htlc_maximum_msat: OptionalField::Present(100_000),
2942                         fee_base_msat: 0,
2943                         fee_proportional_millionths: 0,
2944                         excess_data: Vec::new()
2945                 });
2946
2947                 // Path via {node7, node2} is channels {12, 13, 5}.
2948                 // We already limited them to 200 sats (they are used twice for 100 sats).
2949                 // Nothing to do here.
2950
2951                 {
2952                         // Attempt to route more than available results in a failure.
2953                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2954                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 350_000, 42, Arc::clone(&logger)) {
2955                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2956                         } else { panic!(); }
2957                 }
2958
2959                 {
2960                         // Now, attempt to route 300 sats (exact amount we can route).
2961                         // Our algorithm should provide us with these 3 paths, 100 sats each.
2962                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2963                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 300_000, 42, Arc::clone(&logger)).unwrap();
2964                         assert_eq!(route.paths.len(), 3);
2965
2966                         let mut total_amount_paid_msat = 0;
2967                         for path in &route.paths {
2968                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
2969                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2970                         }
2971                         assert_eq!(total_amount_paid_msat, 300_000);
2972                 }
2973
2974         }
2975
2976         #[test]
2977         fn mpp_cheaper_route_test() {
2978                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2979                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2980
2981                 // This test checks that if we have two cheaper paths and one more expensive path,
2982                 // so that liquidity-wise any 2 of 3 combination is sufficient,
2983                 // two cheaper paths will be taken.
2984                 // These paths have equal available liquidity.
2985
2986                 // We need a combination of 3 paths:
2987                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
2988                 // Note that these paths overlap (channels 5, 12, 13).
2989                 // Each path will have 100 sats capacity, those channels which
2990                 // are used twice will have 200 sats capacity.
2991
2992                 // Disable other potential paths.
2993                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2994                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2995                         short_channel_id: 2,
2996                         timestamp: 2,
2997                         flags: 2,
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                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3006                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3007                         short_channel_id: 7,
3008                         timestamp: 2,
3009                         flags: 2,
3010                         cltv_expiry_delta: 0,
3011                         htlc_minimum_msat: 0,
3012                         htlc_maximum_msat: OptionalField::Present(100_000),
3013                         fee_base_msat: 0,
3014                         fee_proportional_millionths: 0,
3015                         excess_data: Vec::new()
3016                 });
3017
3018                 // Path via {node0, node2} is channels {1, 3, 5}.
3019                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3020                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3021                         short_channel_id: 1,
3022                         timestamp: 2,
3023                         flags: 0,
3024                         cltv_expiry_delta: 0,
3025                         htlc_minimum_msat: 0,
3026                         htlc_maximum_msat: OptionalField::Present(100_000),
3027                         fee_base_msat: 0,
3028                         fee_proportional_millionths: 0,
3029                         excess_data: Vec::new()
3030                 });
3031                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3032                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3033                         short_channel_id: 3,
3034                         timestamp: 2,
3035                         flags: 0,
3036                         cltv_expiry_delta: 0,
3037                         htlc_minimum_msat: 0,
3038                         htlc_maximum_msat: OptionalField::Present(100_000),
3039                         fee_base_msat: 0,
3040                         fee_proportional_millionths: 0,
3041                         excess_data: Vec::new()
3042                 });
3043
3044                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3045                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3046                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3047                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3048                         short_channel_id: 5,
3049                         timestamp: 2,
3050                         flags: 0,
3051                         cltv_expiry_delta: 0,
3052                         htlc_minimum_msat: 0,
3053                         htlc_maximum_msat: OptionalField::Present(200_000),
3054                         fee_base_msat: 0,
3055                         fee_proportional_millionths: 0,
3056                         excess_data: Vec::new()
3057                 });
3058
3059                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3060                 // Add 100 sats to the capacities of {12, 13}, because these channels
3061                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3062                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3063                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3064                         short_channel_id: 12,
3065                         timestamp: 2,
3066                         flags: 0,
3067                         cltv_expiry_delta: 0,
3068                         htlc_minimum_msat: 0,
3069                         htlc_maximum_msat: OptionalField::Present(200_000),
3070                         fee_base_msat: 0,
3071                         fee_proportional_millionths: 0,
3072                         excess_data: Vec::new()
3073                 });
3074                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3075                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3076                         short_channel_id: 13,
3077                         timestamp: 2,
3078                         flags: 0,
3079                         cltv_expiry_delta: 0,
3080                         htlc_minimum_msat: 0,
3081                         htlc_maximum_msat: OptionalField::Present(200_000),
3082                         fee_base_msat: 0,
3083                         fee_proportional_millionths: 0,
3084                         excess_data: Vec::new()
3085                 });
3086
3087                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3088                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3089                         short_channel_id: 6,
3090                         timestamp: 2,
3091                         flags: 0,
3092                         cltv_expiry_delta: 0,
3093                         htlc_minimum_msat: 0,
3094                         htlc_maximum_msat: OptionalField::Present(100_000),
3095                         fee_base_msat: 1_000,
3096                         fee_proportional_millionths: 0,
3097                         excess_data: Vec::new()
3098                 });
3099                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3100                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3101                         short_channel_id: 11,
3102                         timestamp: 2,
3103                         flags: 0,
3104                         cltv_expiry_delta: 0,
3105                         htlc_minimum_msat: 0,
3106                         htlc_maximum_msat: OptionalField::Present(100_000),
3107                         fee_base_msat: 0,
3108                         fee_proportional_millionths: 0,
3109                         excess_data: Vec::new()
3110                 });
3111
3112                 // Path via {node7, node2} is channels {12, 13, 5}.
3113                 // We already limited them to 200 sats (they are used twice for 100 sats).
3114                 // Nothing to do here.
3115
3116                 {
3117                         // Now, attempt to route 180 sats.
3118                         // Our algorithm should provide us with these 2 paths.
3119                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3120                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 180_000, 42, Arc::clone(&logger)).unwrap();
3121                         assert_eq!(route.paths.len(), 2);
3122
3123                         let mut total_value_transferred_msat = 0;
3124                         let mut total_paid_msat = 0;
3125                         for path in &route.paths {
3126                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3127                                 total_value_transferred_msat += path.last().unwrap().fee_msat;
3128                                 for hop in path {
3129                                         total_paid_msat += hop.fee_msat;
3130                                 }
3131                         }
3132                         // If we paid fee, this would be higher.
3133                         assert_eq!(total_value_transferred_msat, 180_000);
3134                         let total_fees_paid = total_paid_msat - total_value_transferred_msat;
3135                         assert_eq!(total_fees_paid, 0);
3136                 }
3137         }
3138
3139         #[test]
3140         fn fees_on_mpp_route_test() {
3141                 // This test makes sure that MPP algorithm properly takes into account
3142                 // fees charged on the channels, by making the fees impactful:
3143                 // if the fee is not properly accounted for, the behavior is different.
3144                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3145                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3146
3147                 // We need a route consisting of 2 paths:
3148                 // From our node to node3 via {node0, node2} and {node7, node2, node4}.
3149                 // We will route 200 sats, Each path will have 100 sats capacity.
3150
3151                 // This test is not particularly stable: e.g.,
3152                 // there's a way to route via {node0, node2, node4}.
3153                 // It works while pathfinding is deterministic, but can be broken otherwise.
3154                 // It's fine to ignore this concern for now.
3155
3156                 // Disable other potential paths.
3157                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3158                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3159                         short_channel_id: 2,
3160                         timestamp: 2,
3161                         flags: 2,
3162                         cltv_expiry_delta: 0,
3163                         htlc_minimum_msat: 0,
3164                         htlc_maximum_msat: OptionalField::Present(100_000),
3165                         fee_base_msat: 0,
3166                         fee_proportional_millionths: 0,
3167                         excess_data: Vec::new()
3168                 });
3169
3170                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3171                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3172                         short_channel_id: 7,
3173                         timestamp: 2,
3174                         flags: 2,
3175                         cltv_expiry_delta: 0,
3176                         htlc_minimum_msat: 0,
3177                         htlc_maximum_msat: OptionalField::Present(100_000),
3178                         fee_base_msat: 0,
3179                         fee_proportional_millionths: 0,
3180                         excess_data: Vec::new()
3181                 });
3182
3183                 // Path via {node0, node2} is channels {1, 3, 5}.
3184                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3185                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3186                         short_channel_id: 1,
3187                         timestamp: 2,
3188                         flags: 0,
3189                         cltv_expiry_delta: 0,
3190                         htlc_minimum_msat: 0,
3191                         htlc_maximum_msat: OptionalField::Present(100_000),
3192                         fee_base_msat: 0,
3193                         fee_proportional_millionths: 0,
3194                         excess_data: Vec::new()
3195                 });
3196                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3197                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3198                         short_channel_id: 3,
3199                         timestamp: 2,
3200                         flags: 0,
3201                         cltv_expiry_delta: 0,
3202                         htlc_minimum_msat: 0,
3203                         htlc_maximum_msat: OptionalField::Present(100_000),
3204                         fee_base_msat: 0,
3205                         fee_proportional_millionths: 0,
3206                         excess_data: Vec::new()
3207                 });
3208
3209                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3210                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3211                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3212                         short_channel_id: 5,
3213                         timestamp: 2,
3214                         flags: 0,
3215                         cltv_expiry_delta: 0,
3216                         htlc_minimum_msat: 0,
3217                         htlc_maximum_msat: OptionalField::Present(100_000),
3218                         fee_base_msat: 0,
3219                         fee_proportional_millionths: 0,
3220                         excess_data: Vec::new()
3221                 });
3222
3223                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3224                 // All channels should be 100 sats capacity. But for the fee experiment,
3225                 // we'll add absolute fee of 150 sats paid for the use channel 6 (paid to node2 on channel 13).
3226                 // Since channel 12 allows to deliver only 250 sats to channel 13, channel 13 can transfer only
3227                 // 100 sats (and pay 150 sats in fees for the use of channel 6),
3228                 // so no matter how large are other channels,
3229                 // the whole path will be limited by 100 sats with just these 2 conditions:
3230                 // - channel 12 capacity is 250 sats
3231                 // - fee for channel 6 is 150 sats
3232                 // Let's test this by enforcing these 2 conditions and removing other limits.
3233                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3234                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3235                         short_channel_id: 12,
3236                         timestamp: 2,
3237                         flags: 0,
3238                         cltv_expiry_delta: 0,
3239                         htlc_minimum_msat: 0,
3240                         htlc_maximum_msat: OptionalField::Present(250_000),
3241                         fee_base_msat: 0,
3242                         fee_proportional_millionths: 0,
3243                         excess_data: Vec::new()
3244                 });
3245                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3246                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3247                         short_channel_id: 13,
3248                         timestamp: 2,
3249                         flags: 0,
3250                         cltv_expiry_delta: 0,
3251                         htlc_minimum_msat: 0,
3252                         htlc_maximum_msat: OptionalField::Absent,
3253                         fee_base_msat: 0,
3254                         fee_proportional_millionths: 0,
3255                         excess_data: Vec::new()
3256                 });
3257
3258                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3259                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3260                         short_channel_id: 6,
3261                         timestamp: 2,
3262                         flags: 0,
3263                         cltv_expiry_delta: 0,
3264                         htlc_minimum_msat: 0,
3265                         htlc_maximum_msat: OptionalField::Absent,
3266                         fee_base_msat: 150_000,
3267                         fee_proportional_millionths: 0,
3268                         excess_data: Vec::new()
3269                 });
3270                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3271                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3272                         short_channel_id: 11,
3273                         timestamp: 2,
3274                         flags: 0,
3275                         cltv_expiry_delta: 0,
3276                         htlc_minimum_msat: 0,
3277                         htlc_maximum_msat: OptionalField::Absent,
3278                         fee_base_msat: 0,
3279                         fee_proportional_millionths: 0,
3280                         excess_data: Vec::new()
3281                 });
3282
3283                 {
3284                         // Attempt to route more than available results in a failure.
3285                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3286                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 210_000, 42, Arc::clone(&logger)) {
3287                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3288                         } else { panic!(); }
3289                 }
3290
3291                 {
3292                         // Now, attempt to route 200 sats (exact amount we can route).
3293                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3294                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 200_000, 42, Arc::clone(&logger)).unwrap();
3295                         assert_eq!(route.paths.len(), 2);
3296
3297                         let mut total_amount_paid_msat = 0;
3298                         for path in &route.paths {
3299                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3300                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3301                         }
3302                         assert_eq!(total_amount_paid_msat, 200_000);
3303                 }
3304
3305         }
3306
3307         #[test]
3308         fn drop_lowest_channel_mpp_route_test() {
3309                 // This test checks that low-capacity channel is dropped when after
3310                 // path finding we realize that we found more capacity than we need.
3311                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3312                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3313
3314                 // We need a route consisting of 3 paths:
3315                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
3316
3317                 // The first and the second paths should be sufficient, but the third should be
3318                 // cheaper, so that we select it but drop later.
3319
3320                 // First, we set limits on these (previously unlimited) channels.
3321                 // Their aggregate capacity will be 50 + 60 + 20 = 130 sats.
3322
3323                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50);
3324                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3325                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3326                         short_channel_id: 1,
3327                         timestamp: 2,
3328                         flags: 0,
3329                         cltv_expiry_delta: 0,
3330                         htlc_minimum_msat: 0,
3331                         htlc_maximum_msat: OptionalField::Present(100_000),
3332                         fee_base_msat: 0,
3333                         fee_proportional_millionths: 0,
3334                         excess_data: Vec::new()
3335                 });
3336                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3337                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3338                         short_channel_id: 3,
3339                         timestamp: 2,
3340                         flags: 0,
3341                         cltv_expiry_delta: 0,
3342                         htlc_minimum_msat: 0,
3343                         htlc_maximum_msat: OptionalField::Present(50_000),
3344                         fee_base_msat: 100,
3345                         fee_proportional_millionths: 0,
3346                         excess_data: Vec::new()
3347                 });
3348
3349                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats (total limit 60);
3350                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3351                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3352                         short_channel_id: 12,
3353                         timestamp: 2,
3354                         flags: 0,
3355                         cltv_expiry_delta: 0,
3356                         htlc_minimum_msat: 0,
3357                         htlc_maximum_msat: OptionalField::Present(60_000),
3358                         fee_base_msat: 100,
3359                         fee_proportional_millionths: 0,
3360                         excess_data: Vec::new()
3361                 });
3362                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3363                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3364                         short_channel_id: 13,
3365                         timestamp: 2,
3366                         flags: 0,
3367                         cltv_expiry_delta: 0,
3368                         htlc_minimum_msat: 0,
3369                         htlc_maximum_msat: OptionalField::Present(60_000),
3370                         fee_base_msat: 0,
3371                         fee_proportional_millionths: 0,
3372                         excess_data: Vec::new()
3373                 });
3374
3375                 // Path via node1 is channels {2, 4}. Limit them to 20 and 20 sats (total capacity 20 sats).
3376                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3377                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3378                         short_channel_id: 2,
3379                         timestamp: 2,
3380                         flags: 0,
3381                         cltv_expiry_delta: 0,
3382                         htlc_minimum_msat: 0,
3383                         htlc_maximum_msat: OptionalField::Present(20_000),
3384                         fee_base_msat: 0,
3385                         fee_proportional_millionths: 0,
3386                         excess_data: Vec::new()
3387                 });
3388                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3389                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3390                         short_channel_id: 4,
3391                         timestamp: 2,
3392                         flags: 0,
3393                         cltv_expiry_delta: 0,
3394                         htlc_minimum_msat: 0,
3395                         htlc_maximum_msat: OptionalField::Present(20_000),
3396                         fee_base_msat: 0,
3397                         fee_proportional_millionths: 0,
3398                         excess_data: Vec::new()
3399                 });
3400
3401                 {
3402                         // Attempt to route more than available results in a failure.
3403                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3404                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 150_000, 42, Arc::clone(&logger)) {
3405                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3406                         } else { panic!(); }
3407                 }
3408
3409                 {
3410                         // Now, attempt to route 125 sats (just a bit below the capacity of 3 channels).
3411                         // Our algorithm should provide us with these 3 paths.
3412                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3413                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 125_000, 42, Arc::clone(&logger)).unwrap();
3414                         assert_eq!(route.paths.len(), 3);
3415                         let mut total_amount_paid_msat = 0;
3416                         for path in &route.paths {
3417                                 assert_eq!(path.len(), 2);
3418                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3419                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3420                         }
3421                         assert_eq!(total_amount_paid_msat, 125_000);
3422                 }
3423
3424                 {
3425                         // Attempt to route without the last small cheap channel
3426                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3427                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
3428                         assert_eq!(route.paths.len(), 2);
3429                         let mut total_amount_paid_msat = 0;
3430                         for path in &route.paths {
3431                                 assert_eq!(path.len(), 2);
3432                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3433                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3434                         }
3435                         assert_eq!(total_amount_paid_msat, 90_000);
3436                 }
3437         }
3438 }
3439
3440 #[cfg(all(test, feature = "unstable"))]
3441 mod benches {
3442         use super::*;
3443         use util::logger::{Logger, Record};
3444
3445         use std::fs::File;
3446         use test::Bencher;
3447
3448         struct DummyLogger {}
3449         impl Logger for DummyLogger {
3450                 fn log(&self, _record: &Record) {}
3451         }
3452
3453         #[bench]
3454         fn generate_routes(bench: &mut Bencher) {
3455                 let mut d = File::open("net_graph-2021-02-12.bin").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");
3456                 let graph = NetworkGraph::read(&mut d).unwrap();
3457
3458                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3459                 let mut path_endpoints = Vec::new();
3460                 let mut seed: usize = 0xdeadbeef;
3461                 'load_endpoints: for _ in 0..100 {
3462                         loop {
3463                                 seed *= 0xdeadbeef;
3464                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3465                                 seed *= 0xdeadbeef;
3466                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3467                                 let amt = seed as u64 % 1_000_000;
3468                                 if get_route(src, &graph, dst, None, None, &[], amt, 42, &DummyLogger{}).is_ok() {
3469                                         path_endpoints.push((src, dst, amt));
3470                                         continue 'load_endpoints;
3471                                 }
3472                         }
3473                 }
3474
3475                 // ...then benchmark finding paths between the nodes we learned.
3476                 let mut idx = 0;
3477                 bench.iter(|| {
3478                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
3479                         assert!(get_route(src, &graph, dst, None, None, &[], amt, 42, &DummyLogger{}).is_ok());
3480                         idx += 1;
3481                 });
3482         }
3483
3484         #[bench]
3485         fn generate_mpp_routes(bench: &mut Bencher) {
3486                 let mut d = File::open("net_graph-2021-02-12.bin").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");
3487                 let graph = NetworkGraph::read(&mut d).unwrap();
3488
3489                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3490                 let mut path_endpoints = Vec::new();
3491                 let mut seed: usize = 0xdeadbeef;
3492                 'load_endpoints: for _ in 0..100 {
3493                         loop {
3494                                 seed *= 0xdeadbeef;
3495                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3496                                 seed *= 0xdeadbeef;
3497                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3498                                 let amt = seed as u64 % 1_000_000;
3499                                 if get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &DummyLogger{}).is_ok() {
3500                                         path_endpoints.push((src, dst, amt));
3501                                         continue 'load_endpoints;
3502                                 }
3503                         }
3504                 }
3505
3506                 // ...then benchmark finding paths between the nodes we learned.
3507                 let mut idx = 0;
3508                 bench.iter(|| {
3509                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
3510                         assert!(get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &DummyLogger{}).is_ok());
3511                         idx += 1;
3512                 });
3513         }
3514 }