git.bitcoin.ninja Git - rust-lightning/blob - lightning/src/routing/router.rs

   1 // This file is Copyright its original authors, visible in version control
   2 // history.
   3 //
   4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
   5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
   7 // You may not use this file except in accordance with one or both of these
   8 // licenses.
   9
  10 //! The top-level routing/network map tracking logic lives here.
  11 //!
  12 //! You probably want to create a NetGraphMsgHandler and use that as your RoutingMessageHandler and then
  13 //! interrogate it to get routes for your own payments.
  14
  15 use bitcoin::secp256k1::key::PublicKey;
  16
  17 use ln::channelmanager::ChannelDetails;
  18 use ln::features::{ChannelFeatures, InvoiceFeatures, NodeFeatures};
  19 use ln::msgs::{DecodeError, ErrorAction, LightningError, MAX_VALUE_MSAT};
  20 use routing::network_graph::{NetworkGraph, RoutingFees};
  21 use util::ser::{Writeable, Readable};
  22 use util::logger::Logger;
  23
  24 use std::cmp;
  25 use std::collections::{HashMap, BinaryHeap};
  26 use std::ops::Deref;
  27
  28 /// A hop in a route
  29 #[derive(Clone, PartialEq)]
  30 pub struct RouteHop {
  31         /// The node_id of the node at this hop.
  32         pub pubkey: PublicKey,
  33         /// The node_announcement features of the node at this hop. For the last hop, these may be
  34         /// amended to match the features present in the invoice this node generated.
  35         pub node_features: NodeFeatures,
  36         /// The channel that should be used from the previous hop to reach this node.
  37         pub short_channel_id: u64,
  38         /// The channel_announcement features of the channel that should be used from the previous hop
  39         /// to reach this node.
  40         pub channel_features: ChannelFeatures,
  41         /// The fee taken on this hop (for paying for the use of the *next* channel in the path).
  42         /// For the last hop, this should be the full value of the payment (might be more than
  43         /// requested if we had to match htlc_minimum_msat).
  44         pub fee_msat: u64,
  45         /// The CLTV delta added for this hop. For the last hop, this should be the full CLTV value
  46         /// expected at the destination, in excess of the current block height.
  47         pub cltv_expiry_delta: u32,
  48 }
  49
  50 /// (C-not exported)
  51 impl Writeable for Vec<RouteHop> {
  52         fn write<W: ::util::ser::Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
  53                 (self.len() as u8).write(writer)?;
  54                 for hop in self.iter() {
  55                         hop.pubkey.write(writer)?;
  56                         hop.node_features.write(writer)?;
  57                         hop.short_channel_id.write(writer)?;
  58                         hop.channel_features.write(writer)?;
  59                         hop.fee_msat.write(writer)?;
  60                         hop.cltv_expiry_delta.write(writer)?;
  61                 }
  62                 Ok(())
  63         }
  64 }
  65
  66 /// (C-not exported)
  67 impl Readable for Vec<RouteHop> {
  68         fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Vec<RouteHop>, DecodeError> {
  69                 let hops_count: u8 = Readable::read(reader)?;
  70                 let mut hops = Vec::with_capacity(hops_count as usize);
  71                 for _ in 0..hops_count {
  72                         hops.push(RouteHop {
  73                                 pubkey: Readable::read(reader)?,
  74                                 node_features: Readable::read(reader)?,
  75                                 short_channel_id: Readable::read(reader)?,
  76                                 channel_features: Readable::read(reader)?,
  77                                 fee_msat: Readable::read(reader)?,
  78                                 cltv_expiry_delta: Readable::read(reader)?,
  79                         });
  80                 }
  81                 Ok(hops)
  82         }
  83 }
  84
  85 /// A route directs a payment from the sender (us) to the recipient. If the recipient supports MPP,
  86 /// it can take multiple paths. Each path is composed of one or more hops through the network.
  87 #[derive(Clone, PartialEq)]
  88 pub struct Route {
  89         /// The list of routes taken for a single (potentially-)multi-part payment. The pubkey of the
  90         /// last RouteHop in each path must be the same.
  91         /// Each entry represents a list of hops, NOT INCLUDING our own, where the last hop is the
  92         /// destination. Thus, this must always be at least length one. While the maximum length of any
  93         /// given path is variable, keeping the length of any path to less than 20 should currently
  94         /// ensure it is viable.
  95         pub paths: Vec<Vec<RouteHop>>,
  96 }
  97
  98 impl Writeable for Route {
  99         fn write<W: ::util::ser::Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
 100                 (self.paths.len() as u64).write(writer)?;
 101                 for hops in self.paths.iter() {
 102                         hops.write(writer)?;
 103                 }
 104                 Ok(())
 105         }
 106 }
 107
 108 impl Readable for Route {
 109         fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Route, DecodeError> {
 110                 let path_count: u64 = Readable::read(reader)?;
 111                 let mut paths = Vec::with_capacity(cmp::min(path_count, 128) as usize);
 112                 for _ in 0..path_count {
 113                         paths.push(Readable::read(reader)?);
 114                 }
 115                 Ok(Route { paths })
 116         }
 117 }
 118
 119 /// A channel descriptor which provides a last-hop route to get_route
 120 #[derive(Clone)]
 121 pub struct RouteHint {
 122         /// The node_id of the non-target end of the route
 123         pub src_node_id: PublicKey,
 124         /// The short_channel_id of this channel
 125         pub short_channel_id: u64,
 126         /// The fees which must be paid to use this channel
 127         pub fees: RoutingFees,
 128         /// The difference in CLTV values between this node and the next node.
 129         pub cltv_expiry_delta: u16,
 130         /// The minimum value, in msat, which must be relayed to the next hop.
 131         pub htlc_minimum_msat: Option<u64>,
 132         /// The maximum value in msat available for routing with a single HTLC.
 133         pub htlc_maximum_msat: Option<u64>,
 134 }
 135
 136 #[derive(Eq, PartialEq)]
 137 struct RouteGraphNode {
 138         pubkey: PublicKey,
 139         lowest_fee_to_peer_through_node: u64,
 140         lowest_fee_to_node: u64,
 141         // The maximum value a yet-to-be-constructed payment path might flow through this node.
 142         // This value is upper-bounded by us by:
 143         // - how much is needed for a path being constructed
 144         // - how much value can channels following this node (up to the destination) can contribute,
 145         //   considering their capacity and fees
 146         value_contribution_msat: u64,
 147         /// The maximum htlc_minimum_msat along the path, taking into consideration the fees required
 148         /// to meet the minimum over the hops required to get there.
 149         path_htlc_minimum_msat: u64,
 150 }
 151
 152 impl cmp::Ord for RouteGraphNode {
 153         fn cmp(&self, other: &RouteGraphNode) -> cmp::Ordering {
 154                 cmp::max(other.lowest_fee_to_peer_through_node, other.path_htlc_minimum_msat)
 155                         .cmp(&cmp::max(self.lowest_fee_to_peer_through_node, self.path_htlc_minimum_msat))
 156                         .then_with(|| other.pubkey.serialize().cmp(&self.pubkey.serialize()))
 157         }
 158 }
 159
 160 impl cmp::PartialOrd for RouteGraphNode {
 161         fn partial_cmp(&self, other: &RouteGraphNode) -> Option<cmp::Ordering> {
 162                 Some(self.cmp(other))
 163         }
 164 }
 165
 166 struct DummyDirectionalChannelInfo {
 167         cltv_expiry_delta: u32,
 168         htlc_minimum_msat: u64,
 169         htlc_maximum_msat: Option<u64>,
 170         fees: RoutingFees,
 171 }
 172
 173 /// It's useful to keep track of the hops associated with the fees required to use them,
 174 /// so that we can choose cheaper paths (as per Dijkstra's algorithm).
 175 /// Fee values should be updated only in the context of the whole path, see update_value_and_recompute_fees.
 176 /// These fee values are useful to choose hops as we traverse the graph "payee-to-payer".
 177 #[derive(Clone)]
 178 struct PathBuildingHop {
 179         /// Hop-specific details unrelated to the path during the routing phase,
 180         /// but rather relevant to the LN graph.
 181         route_hop: RouteHop,
 182         /// Minimal fees required to route to the source node of the current hop via any of its inbound channels.
 183         src_lowest_inbound_fees: RoutingFees,
 184         /// Fees of the channel used in this hop.
 185         channel_fees: RoutingFees,
 186         /// All the fees paid *after* this channel on the way to the destination
 187         next_hops_fee_msat: u64,
 188         /// Fee paid for the use of the current channel (see channel_fees).
 189         /// The value will be actually deducted from the counterparty balance on the previous link.
 190         hop_use_fee_msat: u64,
 191         /// Used to compare channels when choosing the for routing.
 192         /// Includes paying for the use of a hop and the following hops, as well as
 193         /// an estimated cost of reaching this hop.
 194         /// Might get stale when fees are recomputed. Primarily for internal use.
 195         total_fee_msat: u64,
 196         /// This is useful for update_value_and_recompute_fees to make sure
 197         /// we don't fall below the minimum. Should not be updated manually and
 198         /// generally should not be accessed.
 199         htlc_minimum_msat: u64,
 200         /// A mirror of the same field in RouteGraphNode. Note that this is only used during the graph
 201         /// walk and may be invalid thereafter.
 202         path_htlc_minimum_msat: u64,
 203 }
 204
 205 // Instantiated with a list of hops with correct data in them collected during path finding,
 206 // an instance of this struct should be further modified only via given methods.
 207 #[derive(Clone)]
 208 struct PaymentPath {
 209         hops: Vec<PathBuildingHop>,
 210 }
 211
 212 impl PaymentPath {
 213
 214         // TODO: Add a value_msat field to PaymentPath and use it instead of this function.
 215         fn get_value_msat(&self) -> u64 {
 216                 self.hops.last().unwrap().route_hop.fee_msat
 217         }
 218
 219         fn get_total_fee_paid_msat(&self) -> u64 {
 220                 if self.hops.len() < 1 {
 221                         return 0;
 222                 }
 223                 let mut result = 0;
 224                 // Can't use next_hops_fee_msat because it gets outdated.
 225                 for (i, hop) in self.hops.iter().enumerate() {
 226                         if i != self.hops.len() - 1 {
 227                                 result += hop.route_hop.fee_msat;
 228                         }
 229                 }
 230                 return result;
 231         }
 232
 233         // If the amount transferred by the path is updated, the fees should be adjusted. Any other way
 234         // to change fees may result in an inconsistency.
 235         //
 236         // Sometimes we call this function right after constructing a path which has inconsistent
 237         // (in terms of reaching htlc_minimum_msat), so that this function puts the fees in order.
 238         // In that case we call it on the "same" amount we initially allocated for this path, and which
 239         // could have been reduced on the way. In that case, there is also a risk of exceeding
 240         // available_liquidity inside this function, because the function is unaware of this bound.
 241         // In our specific recomputation cases where we never increase the value the risk is pretty low.
 242         // This function, however, does not support arbitrarily increasing the value being transferred,
 243         // and the exception will be triggered.
 244         fn update_value_and_recompute_fees(&mut self, value_msat: u64) {
 245                 assert!(value_msat <= self.hops.last().unwrap().route_hop.fee_msat);
 246
 247                 let mut total_fee_paid_msat = 0 as u64;
 248                 for i in (0..self.hops.len()).rev() {
 249                         let last_hop = i == self.hops.len() - 1;
 250
 251                         // For non-last-hop, this value will represent the fees paid on the current hop. It
 252                         // will consist of the fees for the use of the next hop, and extra fees to match
 253                         // htlc_minimum_msat of the current channel. Last hop is handled separately.
 254                         let mut cur_hop_fees_msat = 0;
 255                         if !last_hop {
 256                                 cur_hop_fees_msat = self.hops.get(i + 1).unwrap().hop_use_fee_msat;
 257                         }
 258
 259                         let mut cur_hop = self.hops.get_mut(i).unwrap();
 260                         cur_hop.next_hops_fee_msat = total_fee_paid_msat;
 261                         // Overpay in fees if we can't save these funds due to htlc_minimum_msat.
 262                         // We try to account for htlc_minimum_msat in scoring (add_entry!), so that nodes don't
 263                         // set it too high just to maliciously take more fees by exploiting this
 264                         // match htlc_minimum_msat logic.
 265                         let mut cur_hop_transferred_amount_msat = total_fee_paid_msat + value_msat;
 266                         if let Some(extra_fees_msat) = cur_hop.htlc_minimum_msat.checked_sub(cur_hop_transferred_amount_msat) {
 267                                 // Note that there is a risk that *previous hops* (those closer to us, as we go
 268                                 // payee->our_node here) would exceed their htlc_maximum_msat or available balance.
 269                                 //
 270                                 // This might make us end up with a broken route, although this should be super-rare
 271                                 // in practice, both because of how healthy channels look like, and how we pick
 272                                 // channels in add_entry.
 273                                 // Also, this can't be exploited more heavily than *announce a free path and fail
 274                                 // all payments*.
 275                                 cur_hop_transferred_amount_msat += extra_fees_msat;
 276                                 total_fee_paid_msat += extra_fees_msat;
 277                                 cur_hop_fees_msat += extra_fees_msat;
 278                         }
 279
 280                         if last_hop {
 281                                 // Final hop is a special case: it usually has just value_msat (by design), but also
 282                                 // it still could overpay for the htlc_minimum_msat.
 283                                 cur_hop.route_hop.fee_msat = cur_hop_transferred_amount_msat;
 284                         } else {
 285                                 // Propagate updated fees for the use of the channels to one hop back, where they
 286                                 // will be actually paid (fee_msat). The last hop is handled above separately.
 287                                 cur_hop.route_hop.fee_msat = cur_hop_fees_msat;
 288                         }
 289
 290                         // Fee for the use of the current hop which will be deducted on the previous hop.
 291                         // Irrelevant for the first hop, as it doesn't have the previous hop, and the use of
 292                         // this channel is free for us.
 293                         if i != 0 {
 294                                 if let Some(new_fee) = compute_fees(cur_hop_transferred_amount_msat, cur_hop.channel_fees) {
 295                                         cur_hop.hop_use_fee_msat = new_fee;
 296                                         total_fee_paid_msat += new_fee;
 297                                 } else {
 298                                         // It should not be possible because this function is called only to reduce the
 299                                         // value. In that case, compute_fee was already called with the same fees for
 300                                         // larger amount and there was no overflow.
 301                                         unreachable!();
 302                                 }
 303                         }
 304                 }
 305         }
 306 }
 307
 308 fn compute_fees(amount_msat: u64, channel_fees: RoutingFees) -> Option<u64> {
 309         let proportional_fee_millions =
 310                 amount_msat.checked_mul(channel_fees.proportional_millionths as u64);
 311         if let Some(new_fee) = proportional_fee_millions.and_then(|part| {
 312                         (channel_fees.base_msat as u64).checked_add(part / 1_000_000) }) {
 313
 314                 Some(new_fee)
 315         } else {
 316                 // This function may be (indirectly) called without any verification,
 317                 // with channel_fees provided by a caller. We should handle it gracefully.
 318                 None
 319         }
 320 }
 321
 322 /// Gets a route from us (payer) to the given target node (payee).
 323 ///
 324 /// If the payee provided features in their invoice, they should be provided via payee_features.
 325 /// Without this, MPP will only be used if the payee's features are available in the network graph.
 326 ///
 327 /// Extra routing hops between known nodes and the target will be used if they are included in
 328 /// last_hops.
 329 ///
 330 /// If some channels aren't announced, it may be useful to fill in a first_hops with the
 331 /// results from a local ChannelManager::list_usable_channels() call. If it is filled in, our
 332 /// view of our local channels (from net_graph_msg_handler) will be ignored, and only those
 333 /// in first_hops will be used.
 334 ///
 335 /// Panics if first_hops contains channels without short_channel_ids
 336 /// (ChannelManager::list_usable_channels will never include such channels).
 337 ///
 338 /// The fees on channels from us to next-hops are ignored (as they are assumed to all be
 339 /// equal), however the enabled/disabled bit on such channels as well as the
 340 /// htlc_minimum_msat/htlc_maximum_msat *are* checked as they may change based on the receiving node.
 341 pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, payee: &PublicKey, payee_features: Option<InvoiceFeatures>, first_hops: Option<&[&ChannelDetails]>,
 342         last_hops: &[&RouteHint], final_value_msat: u64, final_cltv: u32, logger: L) -> Result<Route, LightningError> where L::Target: Logger {
 343         // TODO: Obviously *only* using total fee cost sucks. We should consider weighting by
 344         // uptime/success in using a node in the past.
 345         if *payee == *our_node_id {
 346                 return Err(LightningError{err: "Cannot generate a route to ourselves".to_owned(), action: ErrorAction::IgnoreError});
 347         }
 348
 349         if final_value_msat > MAX_VALUE_MSAT {
 350                 return Err(LightningError{err: "Cannot generate a route of more value than all existing satoshis".to_owned(), action: ErrorAction::IgnoreError});
 351         }
 352
 353         if final_value_msat == 0 {
 354                 return Err(LightningError{err: "Cannot send a payment of 0 msat".to_owned(), action: ErrorAction::IgnoreError});
 355         }
 356
 357         for last_hop in last_hops {
 358                 if last_hop.src_node_id == *payee {
 359                         return Err(LightningError{err: "Last hop cannot have a payee as a source.".to_owned(), action: ErrorAction::IgnoreError});
 360                 }
 361         }
 362
 363         // The general routing idea is the following:
 364         // 1. Fill first/last hops communicated by the caller.
 365         // 2. Attempt to construct a path from payer to payee for transferring
 366         //    any ~sufficient (described later) value.
 367         //    If succeed, remember which channels were used and how much liquidity they have available,
 368         //    so that future paths don't rely on the same liquidity.
 369         // 3. Prooceed to the next step if:
 370         //    - we hit the recommended target value;
 371         //    - OR if we could not construct a new path. Any next attempt will fail too.
 372         //    Otherwise, repeat step 2.
 373         // 4. See if we managed to collect paths which aggregately are able to transfer target value
 374         //    (not recommended value). If yes, proceed. If not, fail routing.
 375         // 5. Randomly combine paths into routes having enough to fulfill the payment. (TODO: knapsack)
 376         // 6. Of all the found paths, select only those with the lowest total fee.
 377         // 7. The last path in every selected route is likely to be more than we need.
 378         //    Reduce its value-to-transfer and recompute fees.
 379         // 8. Choose the best route by the lowest total fee.
 380
 381         // As for the actual search algorithm,
 382         // we do a payee-to-payer pseudo-Dijkstra's sorting by each node's distance from the payee
 383         // plus the minimum per-HTLC fee to get from it to another node (aka "shitty pseudo-A*").
 384         //
 385         // We are not a faithful Dijkstra's implementation because we can change values which impact
 386         // earlier nodes while processing later nodes. Specifically, if we reach a channel with a lower
 387         // liquidity limit (via htlc_maximum_msat, on-chain capacity or assumed liquidity limits) then
 388         // the value we are currently attempting to send over a path, we simply reduce the value being
 389         // sent along the path for any hops after that channel. This may imply that later fees (which
 390         // we've already tabulated) are lower because a smaller value is passing through the channels
 391         // (and the proportional fee is thus lower). There isn't a trivial way to recalculate the
 392         // channels which were selected earlier (and which may still be used for other paths without a
 393         // lower liquidity limit), so we simply accept that some liquidity-limited paths may be
 394         // de-preferenced.
 395         //
 396         // One potentially problematic case for this algorithm would be if there are many
 397         // liquidity-limited paths which are liquidity-limited near the destination (ie early in our
 398         // graph walking), we may never find a liquidity-unlimited path which has lower proportional
 399         // fee (and only lower absolute fee when considering the ultimate value sent). Because we only
 400         // consider paths with at least 5% of the total value being sent, the damage from such a case
 401         // should be limited, however this could be further reduced in the future by calculating fees
 402         // on the amount we wish to route over a path, not the amount we are routing over a path.
 403         //
 404         // Alternatively, we could store more detailed path information in the heap (targets, below)
 405         // and index the best-path map (dist, below) by node *and* HTLC limits, however that would blow
 406         // up the runtime significantly both algorithmically (as we'd traverse nodes multiple times)
 407         // and practically (as we would need to store dynamically-allocated path information in heap
 408         // objects, increasing malloc traffic and indirect memory access significantly). Further, the
 409         // results of such an algorithm would likely be biased towards lower-value paths.
 410         //
 411         // Further, we could return to a faithful Dijkstra's algorithm by rejecting paths with limits
 412         // outside of our current search value, running a path search more times to gather candidate
 413         // paths at different values. While this may be acceptable, further path searches may increase
 414         // runtime for little gain. Specifically, the current algorithm rather efficiently explores the
 415         // graph for candidate paths, calculating the maximum value which can realistically be sent at
 416         // the same time, remaining generic across different payment values.
 417         //
 418         // TODO: There are a few tweaks we could do, including possibly pre-calculating more stuff
 419         // to use as the A* heuristic beyond just the cost to get one node further than the current
 420         // one.
 421
 422         let dummy_directional_info = DummyDirectionalChannelInfo { // used for first_hops routes
 423                 cltv_expiry_delta: 0,
 424                 htlc_minimum_msat: 0,
 425                 htlc_maximum_msat: None,
 426                 fees: RoutingFees {
 427                         base_msat: 0,
 428                         proportional_millionths: 0,
 429                 }
 430         };
 431
 432         let mut targets = BinaryHeap::new(); //TODO: Do we care about switching to eg Fibbonaci heap?
 433         let mut dist = HashMap::with_capacity(network.get_nodes().len());
 434
 435         // During routing, if we ignore a path due to an htlc_minimum_msat limit, we set this,
 436         // indicating that we may wish to try again with a higher value, potentially paying to meet an
 437         // htlc_minimum with extra fees while still finding a cheaper path.
 438         let mut hit_minimum_limit;
 439
 440         // When arranging a route, we select multiple paths so that we can make a multi-path payment.
 441         // We start with a path_value of the exact amount we want, and if that generates a route we may
 442         // return it immediately. Otherwise, we don't stop searching for paths until we have 3x the
 443         // amount we want in total across paths, selecting the best subset at the end.
 444         const ROUTE_CAPACITY_PROVISION_FACTOR: u64 = 3;
 445         let recommended_value_msat = final_value_msat * ROUTE_CAPACITY_PROVISION_FACTOR as u64;
 446         let mut path_value_msat = final_value_msat;
 447
 448         // Allow MPP only if we have a features set from somewhere that indicates the payee supports
 449         // it. If the payee supports it they're supposed to include it in the invoice, so that should
 450         // work reliably.
 451         let allow_mpp = if let Some(features) = &payee_features {
 452                 features.supports_basic_mpp()
 453         } else if let Some(node) = network.get_nodes().get(&payee) {
 454                 if let Some(node_info) = node.announcement_info.as_ref() {
 455                         node_info.features.supports_basic_mpp()
 456                 } else { false }
 457         } else { false };
 458
 459         // Step (1).
 460         // Prepare the data we'll use for payee-to-payer search by
 461         // inserting first hops suggested by the caller as targets.
 462         // Our search will then attempt to reach them while traversing from the payee node.
 463         let mut first_hop_targets = HashMap::with_capacity(if first_hops.is_some() { first_hops.as_ref().unwrap().len() } else { 0 });
 464         if let Some(hops) = first_hops {
 465                 for chan in hops {
 466                         let short_channel_id = chan.short_channel_id.expect("first_hops should be filled in with usable channels, not pending ones");
 467                         if chan.remote_network_id == *our_node_id {
 468                                 return Err(LightningError{err: "First hop cannot have our_node_id as a destination.".to_owned(), action: ErrorAction::IgnoreError});
 469                         }
 470                         first_hop_targets.insert(chan.remote_network_id, (short_channel_id, chan.counterparty_features.clone(), chan.outbound_capacity_msat));
 471                 }
 472                 if first_hop_targets.is_empty() {
 473                         return Err(LightningError{err: "Cannot route when there are no outbound routes away from us".to_owned(), action: ErrorAction::IgnoreError});
 474                 }
 475         }
 476
 477         // We don't want multiple paths (as per MPP) share liquidity of the same channels.
 478         // This map allows paths to be aware of the channel use by other paths in the same call.
 479         // This would help to make a better path finding decisions and not "overbook" channels.
 480         // It is unaware of the directions (except for `outbound_capacity_msat` in `first_hops`).
 481         let mut bookkeeped_channels_liquidity_available_msat = HashMap::new();
 482
 483         // Keeping track of how much value we already collected across other paths. Helps to decide:
 484         // - how much a new path should be transferring (upper bound);
 485         // - whether a channel should be disregarded because
 486         //   it's available liquidity is too small comparing to how much more we need to collect;
 487         // - when we want to stop looking for new paths.
 488         let mut already_collected_value_msat = 0;
 489
 490         macro_rules! add_entry {
 491                 // Adds entry which goes from $src_node_id to $dest_node_id
 492                 // over the channel with id $chan_id with fees described in
 493                 // $directional_info.
 494                 // $next_hops_fee_msat represents the fees paid for using all the channel *after* this one,
 495                 // since that value has to be transferred over this channel.
 496                 ( $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,
 497                    $next_hops_value_contribution: expr, $incl_fee_next_hops_htlc_minimum_msat: expr ) => {
 498                         // Channels to self should not be used. This is more of belt-and-suspenders, because in
 499                         // practice these cases should be caught earlier:
 500                         // - for regular channels at channel announcement (TODO)
 501                         // - for first and last hops early in get_route
 502                         if $src_node_id != $dest_node_id.clone() {
 503                                 let available_liquidity_msat = bookkeeped_channels_liquidity_available_msat.entry($chan_id.clone()).or_insert_with(|| {
 504                                         let mut initial_liquidity_available_msat = None;
 505                                         if let Some(capacity_sats) = $capacity_sats {
 506                                                 initial_liquidity_available_msat = Some(capacity_sats * 1000);
 507                                         }
 508
 509                                         if let Some(htlc_maximum_msat) = $directional_info.htlc_maximum_msat {
 510                                                 if let Some(available_msat) = initial_liquidity_available_msat {
 511                                                         initial_liquidity_available_msat = Some(cmp::min(available_msat, htlc_maximum_msat));
 512                                                 } else {
 513                                                         initial_liquidity_available_msat = Some(htlc_maximum_msat);
 514                                                 }
 515                                         }
 516
 517                                         match initial_liquidity_available_msat {
 518                                                 Some(available_msat) => available_msat,
 519                                                 // We assume channels with unknown balance have
 520                                                 // a capacity of 0.0025 BTC (or 250_000 sats).
 521                                                 None => 250_000 * 1000
 522                                         }
 523                                 });
 524
 525                                 // It is tricky to substract $next_hops_fee_msat from available liquidity here.
 526                                 // It may be misleading because we might later choose to reduce the value transferred
 527                                 // over these channels, and the channel which was insufficient might become sufficient.
 528                                 // Worst case: we drop a good channel here because it can't cover the high following
 529                                 // fees caused by one expensive channel, but then this channel could have been used
 530                                 // if the amount being transferred over this path is lower.
 531                                 // We do this for now, but this is a subject for removal.
 532                                 if let Some(available_value_contribution_msat) = available_liquidity_msat.checked_sub($next_hops_fee_msat) {
 533
 534                                         // Routing Fragmentation Mitigation heuristic:
 535                                         //
 536                                         // Routing fragmentation across many payment paths increases the overall routing
 537                                         // fees as you have irreducible routing fees per-link used (`fee_base_msat`).
 538                                         // Taking too many smaller paths also increases the chance of payment failure.
 539                                         // Thus to avoid this effect, we require from our collected links to provide
 540                                         // at least a minimal contribution to the recommended value yet-to-be-fulfilled.
 541                                         //
 542                                         // This requirement is currently 5% of the remaining-to-be-collected value.
 543                                         // This means as we successfully advance in our collection,
 544                                         // the absolute liquidity contribution is lowered,
 545                                         // thus increasing the number of potential channels to be selected.
 546
 547                                         // Derive the minimal liquidity contribution with a ratio of 20 (5%, rounded up)
 548                                         // or 100% if we're not allowed to do multipath payments.
 549                                         let minimal_value_contribution_msat: u64 = if allow_mpp {
 550                                                 (recommended_value_msat - already_collected_value_msat + 19) / 20
 551                                         } else {
 552                                                 final_value_msat
 553                                         };
 554                                         // Verify the liquidity offered by this channel complies to the minimal contribution.
 555                                         let contributes_sufficient_value = available_value_contribution_msat >= minimal_value_contribution_msat;
 556
 557                                         let value_contribution_msat = cmp::min(available_value_contribution_msat, $next_hops_value_contribution);
 558                                         // Includes paying fees for the use of the following channels.
 559                                         let amount_to_transfer_over_msat: u64 = match value_contribution_msat.checked_add($next_hops_fee_msat) {
 560                                                 Some(result) => result,
 561                                                 // Can't overflow due to how the values were computed right above.
 562                                                 None => unreachable!(),
 563                                         };
 564                                         #[allow(unused_comparisons)] // $incl_fee_next_hops_htlc_minimum_msat is 0 in some calls so rustc complains
 565                                         let over_path_minimum_msat = amount_to_transfer_over_msat >= $directional_info.htlc_minimum_msat &&
 566                                                 amount_to_transfer_over_msat >= $incl_fee_next_hops_htlc_minimum_msat;
 567
 568                                         // If HTLC minimum is larger than the amount we're going to transfer, we shouldn't
 569                                         // bother considering this channel.
 570                                         // Since we're choosing amount_to_transfer_over_msat as maximum possible, it can
 571                                         // be only reduced later (not increased), so this channel should just be skipped
 572                                         // as not sufficient.
 573                                         if !over_path_minimum_msat {
 574                                                 hit_minimum_limit = true;
 575                                         } else if contributes_sufficient_value {
 576                                                 // Note that low contribution here (limited by available_liquidity_msat)
 577                                                 // might violate htlc_minimum_msat on the hops which are next along the
 578                                                 // payment path (upstream to the payee). To avoid that, we recompute path
 579                                                 // path fees knowing the final path contribution after constructing it.
 580                                                 let path_htlc_minimum_msat = match compute_fees($incl_fee_next_hops_htlc_minimum_msat, $directional_info.fees)
 581                                                                 .map(|fee_msat| fee_msat.checked_add($incl_fee_next_hops_htlc_minimum_msat)) {
 582                                                         Some(Some(value_msat)) => cmp::max(value_msat, $directional_info.htlc_minimum_msat),
 583                                                         _ => u64::max_value()
 584                                                 };
 585                                                 let hm_entry = dist.entry(&$src_node_id);
 586                                                 let old_entry = hm_entry.or_insert_with(|| {
 587                                                         // If there was previously no known way to access
 588                                                         // the source node (recall it goes payee-to-payer) of $chan_id, first add
 589                                                         // a semi-dummy record just to compute the fees to reach the source node.
 590                                                         // This will affect our decision on selecting $chan_id
 591                                                         // as a way to reach the $dest_node_id.
 592                                                         let mut fee_base_msat = u32::max_value();
 593                                                         let mut fee_proportional_millionths = u32::max_value();
 594                                                         if let Some(Some(fees)) = network.get_nodes().get(&$src_node_id).map(|node| node.lowest_inbound_channel_fees) {
 595                                                                 fee_base_msat = fees.base_msat;
 596                                                                 fee_proportional_millionths = fees.proportional_millionths;
 597                                                         }
 598                                                         PathBuildingHop {
 599                                                                 route_hop: RouteHop {
 600                                                                         pubkey: $dest_node_id.clone(),
 601                                                                         node_features: NodeFeatures::empty(),
 602                                                                         short_channel_id: 0,
 603                                                                         channel_features: $chan_features.clone(),
 604                                                                         fee_msat: 0,
 605                                                                         cltv_expiry_delta: 0,
 606                                                                 },
 607                                                                 src_lowest_inbound_fees: RoutingFees {
 608                                                                         base_msat: fee_base_msat,
 609                                                                         proportional_millionths: fee_proportional_millionths,
 610                                                                 },
 611                                                                 channel_fees: $directional_info.fees,
 612                                                                 next_hops_fee_msat: u64::max_value(),
 613                                                                 hop_use_fee_msat: u64::max_value(),
 614                                                                 total_fee_msat: u64::max_value(),
 615                                                                 htlc_minimum_msat: $directional_info.htlc_minimum_msat,
 616                                                                 path_htlc_minimum_msat,
 617                                                         }
 618                                                 });
 619
 620                                                 let mut hop_use_fee_msat = 0;
 621                                                 let mut total_fee_msat = $next_hops_fee_msat;
 622
 623                                                 // Ignore hop_use_fee_msat for channel-from-us as we assume all channels-from-us
 624                                                 // will have the same effective-fee
 625                                                 if $src_node_id != *our_node_id {
 626                                                         match compute_fees(amount_to_transfer_over_msat, $directional_info.fees) {
 627                                                                 // max_value means we'll always fail
 628                                                                 // the old_entry.total_fee_msat > total_fee_msat check
 629                                                                 None => total_fee_msat = u64::max_value(),
 630                                                                 Some(fee_msat) => {
 631                                                                         hop_use_fee_msat = fee_msat;
 632                                                                         total_fee_msat += hop_use_fee_msat;
 633                                                                         if let Some(prev_hop_fee_msat) = compute_fees(total_fee_msat + amount_to_transfer_over_msat,
 634                                                                                                                                                                 old_entry.src_lowest_inbound_fees) {
 635                                                                                 if let Some(incremented_total_fee_msat) = total_fee_msat.checked_add(prev_hop_fee_msat) {
 636                                                                                         total_fee_msat = incremented_total_fee_msat;
 637                                                                                 }
 638                                                                                 else {
 639                                                                                         // max_value means we'll always fail
 640                                                                                         // the old_entry.total_fee_msat > total_fee_msat check
 641                                                                                         total_fee_msat = u64::max_value();
 642                                                                                 }
 643                                                                         } else {
 644                                                                                 // max_value means we'll always fail
 645                                                                                 // the old_entry.total_fee_msat > total_fee_msat check
 646                                                                                 total_fee_msat = u64::max_value();
 647                                                                         }
 648                                                                 }
 649                                                         }
 650                                                 }
 651
 652                                                 let new_graph_node = RouteGraphNode {
 653                                                         pubkey: $src_node_id,
 654                                                         lowest_fee_to_peer_through_node: total_fee_msat,
 655                                                         lowest_fee_to_node: $next_hops_fee_msat as u64 + hop_use_fee_msat,
 656                                                         value_contribution_msat: value_contribution_msat,
 657                                                         path_htlc_minimum_msat,
 658                                                 };
 659
 660                                                 // Update the way of reaching $src_node_id with the given $chan_id (from $dest_node_id),
 661                                                 // if this way is cheaper than the already known
 662                                                 // (considering the cost to "reach" this channel from the route destination,
 663                                                 // the cost of using this channel,
 664                                                 // and the cost of routing to the source node of this channel).
 665                                                 // Also, consider that htlc_minimum_msat_difference, because we might end up
 666                                                 // paying it. Consider the following exploit:
 667                                                 // we use 2 paths to transfer 1.5 BTC. One of them is 0-fee normal 1 BTC path,
 668                                                 // and for the other one we picked a 1sat-fee path with htlc_minimum_msat of
 669                                                 // 1 BTC. Now, since the latter is more expensive, we gonna try to cut it
 670                                                 // by 0.5 BTC, but then match htlc_minimum_msat by paying a fee of 0.5 BTC
 671                                                 // to this channel.
 672                                                 // Ideally the scoring could be smarter (e.g. 0.5*htlc_minimum_msat here),
 673                                                 // but it may require additional tracking - we don't want to double-count
 674                                                 // the fees included in $incl_fee_next_hops_htlc_minimum_msat, but also
 675                                                 // can't use something that may decrease on future hops.
 676                                                 let old_cost = cmp::max(old_entry.total_fee_msat, old_entry.path_htlc_minimum_msat);
 677                                                 let new_cost = cmp::max(total_fee_msat, path_htlc_minimum_msat);
 678
 679                                                 if new_cost < old_cost {
 680                                                         targets.push(new_graph_node);
 681                                                         old_entry.next_hops_fee_msat = $next_hops_fee_msat;
 682                                                         old_entry.hop_use_fee_msat = hop_use_fee_msat;
 683                                                         old_entry.total_fee_msat = total_fee_msat;
 684                                                         old_entry.route_hop = RouteHop {
 685                                                                 pubkey: $dest_node_id.clone(),
 686                                                                 node_features: NodeFeatures::empty(),
 687                                                                 short_channel_id: $chan_id.clone(),
 688                                                                 channel_features: $chan_features.clone(),
 689                                                                 fee_msat: 0, // This value will be later filled with hop_use_fee_msat of the following channel
 690                                                                 cltv_expiry_delta: $directional_info.cltv_expiry_delta as u32,
 691                                                         };
 692                                                         old_entry.channel_fees = $directional_info.fees;
 693                                                         old_entry.htlc_minimum_msat = $directional_info.htlc_minimum_msat;
 694                                                         old_entry.path_htlc_minimum_msat = path_htlc_minimum_msat;
 695                                                 }
 696                                         }
 697                                 }
 698                         }
 699                 };
 700         }
 701
 702         // Find ways (channels with destination) to reach a given node and store them
 703         // in the corresponding data structures (routing graph etc).
 704         // $fee_to_target_msat represents how much it costs to reach to this node from the payee,
 705         // meaning how much will be paid in fees after this node (to the best of our knowledge).
 706         // This data can later be helpful to optimize routing (pay lower fees).
 707         macro_rules! add_entries_to_cheapest_to_target_node {
 708                 ( $node: expr, $node_id: expr, $fee_to_target_msat: expr, $next_hops_value_contribution: expr, $incl_fee_next_hops_htlc_minimum_msat: expr ) => {
 709                         if first_hops.is_some() {
 710                                 if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat)) = first_hop_targets.get(&$node_id) {
 711                                         add_entry!(first_hop, *our_node_id, $node_id, dummy_directional_info, Some(outbound_capacity_msat / 1000), features.to_context(), $fee_to_target_msat, $next_hops_value_contribution, $incl_fee_next_hops_htlc_minimum_msat);
 712                                 }
 713                         }
 714
 715                         let features;
 716                         if let Some(node_info) = $node.announcement_info.as_ref() {
 717                                 features = node_info.features.clone();
 718                         } else {
 719                                 features = NodeFeatures::empty();
 720                         }
 721
 722                         if !features.requires_unknown_bits() {
 723                                 for chan_id in $node.channels.iter() {
 724                                         let chan = network.get_channels().get(chan_id).unwrap();
 725                                         if !chan.features.requires_unknown_bits() {
 726                                                 if chan.node_one == *$node_id {
 727                                                         // ie $node is one, ie next hop in A* is two, via the two_to_one channel
 728                                                         if first_hops.is_none() || chan.node_two != *our_node_id {
 729                                                                 if let Some(two_to_one) = chan.two_to_one.as_ref() {
 730                                                                         if two_to_one.enabled {
 731                                                                                 add_entry!(chan_id, chan.node_two, chan.node_one, two_to_one, chan.capacity_sats, chan.features, $fee_to_target_msat, $next_hops_value_contribution, $incl_fee_next_hops_htlc_minimum_msat);
 732                                                                         }
 733                                                                 }
 734                                                         }
 735                                                 } else {
 736                                                         if first_hops.is_none() || chan.node_one != *our_node_id {
 737                                                                 if let Some(one_to_two) = chan.one_to_two.as_ref() {
 738                                                                         if one_to_two.enabled {
 739                                                                                 add_entry!(chan_id, chan.node_one, chan.node_two, one_to_two, chan.capacity_sats, chan.features, $fee_to_target_msat, $next_hops_value_contribution, $incl_fee_next_hops_htlc_minimum_msat);
 740                                                                         }
 741                                                                 }
 742
 743                                                         }
 744                                                 }
 745                                         }
 746                                 }
 747                         }
 748                 };
 749         }
 750
 751         let mut payment_paths = Vec::<PaymentPath>::new();
 752
 753         // TODO: diversify by nodes (so that all paths aren't doomed if one node is offline).
 754         'paths_collection: loop {
 755                 // For every new path, start from scratch, except
 756                 // bookkeeped_channels_liquidity_available_msat, which will improve
 757                 // the further iterations of path finding. Also don't erase first_hop_targets.
 758                 targets.clear();
 759                 dist.clear();
 760                 hit_minimum_limit = false;
 761
 762                 // If first hop is a private channel and the only way to reach the payee, this is the only
 763                 // place where it could be added.
 764                 if first_hops.is_some() {
 765                         if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat)) = first_hop_targets.get(&payee) {
 766                                 add_entry!(first_hop, *our_node_id, payee, dummy_directional_info, Some(outbound_capacity_msat / 1000), features.to_context(), 0, path_value_msat, 0);
 767                         }
 768                 }
 769
 770                 // Add the payee as a target, so that the payee-to-payer
 771                 // search algorithm knows what to start with.
 772                 match network.get_nodes().get(payee) {
 773                         // The payee is not in our network graph, so nothing to add here.
 774                         // There is still a chance of reaching them via last_hops though,
 775                         // so don't yet fail the payment here.
 776                         // If not, targets.pop() will not even let us enter the loop in step 2.
 777                         None => {},
 778                         Some(node) => {
 779                                 add_entries_to_cheapest_to_target_node!(node, payee, 0, path_value_msat, 0);
 780                         },
 781                 }
 782
 783                 // Step (1).
 784                 // If a caller provided us with last hops, add them to routing targets. Since this happens
 785                 // earlier than general path finding, they will be somewhat prioritized, although currently
 786                 // it matters only if the fees are exactly the same.
 787                 for hop in last_hops.iter() {
 788                         let have_hop_src_in_graph =
 789                                 if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat)) = first_hop_targets.get(&hop.src_node_id) {
 790                                         // If this hop connects to a node with which we have a direct channel, ignore
 791                                         // the network graph and add both the hop and our direct channel to
 792                                         // the candidate set.
 793                                         //
 794                                         // Currently there are no channel-context features defined, so we are a
 795                                         // bit lazy here. In the future, we should pull them out via our
 796                                         // ChannelManager, but there's no reason to waste the space until we
 797                                         // need them.
 798                                         add_entry!(first_hop, *our_node_id , hop.src_node_id, dummy_directional_info, Some(outbound_capacity_msat / 1000), features.to_context(), 0, path_value_msat, 0);
 799                                         true
 800                                 } else {
 801                                         // In any other case, only add the hop if the source is in the regular network
 802                                         // graph:
 803                                         network.get_nodes().get(&hop.src_node_id).is_some()
 804                                 };
 805                         if have_hop_src_in_graph {
 806                                 // BOLT 11 doesn't allow inclusion of features for the last hop hints, which
 807                                 // really sucks, cause we're gonna need that eventually.
 808                                 let last_path_htlc_minimum_msat: u64 = match hop.htlc_minimum_msat {
 809                                         Some(htlc_minimum_msat) => htlc_minimum_msat,
 810                                         None => 0
 811                                 };
 812                                 let directional_info = DummyDirectionalChannelInfo {
 813                                         cltv_expiry_delta: hop.cltv_expiry_delta as u32,
 814                                         htlc_minimum_msat: last_path_htlc_minimum_msat,
 815                                         htlc_maximum_msat: hop.htlc_maximum_msat,
 816                                         fees: hop.fees,
 817                                 };
 818                                 add_entry!(hop.short_channel_id, hop.src_node_id, payee, directional_info, None::<u64>, ChannelFeatures::empty(), 0, path_value_msat, 0);
 819                         }
 820                 }
 821
 822                 // At this point, targets are filled with the data from first and
 823                 // last hops communicated by the caller, and the payment receiver.
 824                 let mut found_new_path = false;
 825
 826                 // Step (2).
 827                 // If this loop terminates due the exhaustion of targets, two situations are possible:
 828                 // - not enough outgoing liquidity:
 829                 //   0 < already_collected_value_msat < final_value_msat
 830                 // - enough outgoing liquidity:
 831                 //   final_value_msat <= already_collected_value_msat < recommended_value_msat
 832                 // Both these cases (and other cases except reaching recommended_value_msat) mean that
 833                 // paths_collection will be stopped because found_new_path==false.
 834                 // This is not necessarily a routing failure.
 835                 'path_construction: while let Some(RouteGraphNode { pubkey, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat, .. }) = targets.pop() {
 836
 837                         // Since we're going payee-to-payer, hitting our node as a target means we should stop
 838                         // traversing the graph and arrange the path out of what we found.
 839                         if pubkey == *our_node_id {
 840                                 let mut new_entry = dist.remove(&our_node_id).unwrap();
 841                                 let mut ordered_hops = vec!(new_entry.clone());
 842
 843                                 'path_walk: loop {
 844                                         if let Some(&(_, ref features, _)) = first_hop_targets.get(&ordered_hops.last().unwrap().route_hop.pubkey) {
 845                                                 ordered_hops.last_mut().unwrap().route_hop.node_features = features.to_context();
 846                                         } else if let Some(node) = network.get_nodes().get(&ordered_hops.last().unwrap().route_hop.pubkey) {
 847                                                 if let Some(node_info) = node.announcement_info.as_ref() {
 848                                                         ordered_hops.last_mut().unwrap().route_hop.node_features = node_info.features.clone();
 849                                                 } else {
 850                                                         ordered_hops.last_mut().unwrap().route_hop.node_features = NodeFeatures::empty();
 851                                                 }
 852                                         } else {
 853                                                 // We should be able to fill in features for everything except the last
 854                                                 // hop, if the last hop was provided via a BOLT 11 invoice (though we
 855                                                 // should be able to extend it further as BOLT 11 does have feature
 856                                                 // flags for the last hop node itself).
 857                                                 assert!(ordered_hops.last().unwrap().route_hop.pubkey == *payee);
 858                                         }
 859
 860                                         // Means we succesfully traversed from the payer to the payee, now
 861                                         // save this path for the payment route. Also, update the liquidity
 862                                         // remaining on the used hops, so that we take them into account
 863                                         // while looking for more paths.
 864                                         if ordered_hops.last().unwrap().route_hop.pubkey == *payee {
 865                                                 break 'path_walk;
 866                                         }
 867
 868                                         new_entry = match dist.remove(&ordered_hops.last().unwrap().route_hop.pubkey) {
 869                                                 Some(payment_hop) => payment_hop,
 870                                                 // We can't arrive at None because, if we ever add an entry to targets,
 871                                                 // we also fill in the entry in dist (see add_entry!).
 872                                                 None => unreachable!(),
 873                                         };
 874                                         // We "propagate" the fees one hop backward (topologically) here,
 875                                         // so that fees paid for a HTLC forwarding on the current channel are
 876                                         // associated with the previous channel (where they will be subtracted).
 877                                         ordered_hops.last_mut().unwrap().route_hop.fee_msat = new_entry.hop_use_fee_msat;
 878                                         ordered_hops.last_mut().unwrap().route_hop.cltv_expiry_delta = new_entry.route_hop.cltv_expiry_delta;
 879                                         ordered_hops.push(new_entry.clone());
 880                                 }
 881                                 ordered_hops.last_mut().unwrap().route_hop.fee_msat = value_contribution_msat;
 882                                 ordered_hops.last_mut().unwrap().hop_use_fee_msat = 0;
 883                                 ordered_hops.last_mut().unwrap().route_hop.cltv_expiry_delta = final_cltv;
 884
 885                                 let mut payment_path = PaymentPath {hops: ordered_hops};
 886
 887                                 // We could have possibly constructed a slightly inconsistent path: since we reduce
 888                                 // value being transferred along the way, we could have violated htlc_minimum_msat
 889                                 // on some channels we already passed (assuming dest->source direction). Here, we
 890                                 // recompute the fees again, so that if that's the case, we match the currently
 891                                 // underpaid htlc_minimum_msat with fees.
 892                                 payment_path.update_value_and_recompute_fees(value_contribution_msat);
 893
 894                                 // Since a path allows to transfer as much value as
 895                                 // the smallest channel it has ("bottleneck"), we should recompute
 896                                 // the fees so sender HTLC don't overpay fees when traversing
 897                                 // larger channels than the bottleneck. This may happen because
 898                                 // when we were selecting those channels we were not aware how much value
 899                                 // this path will transfer, and the relative fee for them
 900                                 // might have been computed considering a larger value.
 901                                 // Remember that we used these channels so that we don't rely
 902                                 // on the same liquidity in future paths.
 903                                 for payment_hop in payment_path.hops.iter() {
 904                                         let channel_liquidity_available_msat = bookkeeped_channels_liquidity_available_msat.get_mut(&payment_hop.route_hop.short_channel_id).unwrap();
 905                                         let mut spent_on_hop_msat = value_contribution_msat;
 906                                         let next_hops_fee_msat = payment_hop.next_hops_fee_msat;
 907                                         spent_on_hop_msat += next_hops_fee_msat;
 908                                         if *channel_liquidity_available_msat < spent_on_hop_msat {
 909                                                 // This should not happen because we do recompute fees right before,
 910                                                 // trying to avoid cases when a hop is not usable due to the fee situation.
 911                                                 break 'path_construction;
 912                                         }
 913                                         *channel_liquidity_available_msat -= spent_on_hop_msat;
 914                                 }
 915                                 // Track the total amount all our collected paths allow to send so that we:
 916                                 // - know when to stop looking for more paths
 917                                 // - know which of the hops are useless considering how much more sats we need
 918                                 //   (contributes_sufficient_value)
 919                                 already_collected_value_msat += value_contribution_msat;
 920
 921                                 payment_paths.push(payment_path);
 922                                 found_new_path = true;
 923                                 break 'path_construction;
 924                         }
 925
 926                         // Otherwise, since the current target node is not us,
 927                         // keep "unrolling" the payment graph from payee to payer by
 928                         // finding a way to reach the current target from the payer side.
 929                         match network.get_nodes().get(&pubkey) {
 930                                 None => {},
 931                                 Some(node) => {
 932                                         add_entries_to_cheapest_to_target_node!(node, &pubkey, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat);
 933                                 },
 934                         }
 935                 }
 936
 937                 if !allow_mpp {
 938                         // If we don't support MPP, no use trying to gather more value ever.
 939                         break 'paths_collection;
 940                 }
 941
 942                 // Step (3).
 943                 // Stop either when the recommended value is reached or if no new path was found in this
 944                 // iteration.
 945                 // In the latter case, making another path finding attempt won't help,
 946                 // because we deterministically terminated the search due to low liquidity.
 947                 if already_collected_value_msat >= recommended_value_msat || !found_new_path {
 948                         break 'paths_collection;
 949                 }
 950                 // Further, if this was our first walk of the graph, and we weren't limited by an
 951                 // htlc_minim_msat, return immediately because this path should suffice. If we were limited
 952                 // by an htlc_minimum_msat value, find another path with a higher value, potentially
 953                 // allowing us to pay fees to meet the htlc_minimum while still keeping a lower total fee.
 954                 if already_collected_value_msat == final_value_msat && payment_paths.len() == 1 {
 955                         if !hit_minimum_limit {
 956                                 break 'paths_collection;
 957                         }
 958                         path_value_msat = recommended_value_msat;
 959                 }
 960         }
 961
 962         // Step (4).
 963         if payment_paths.len() == 0 {
 964                 return Err(LightningError{err: "Failed to find a path to the given destination".to_owned(), action: ErrorAction::IgnoreError});
 965         }
 966
 967         if already_collected_value_msat < final_value_msat {
 968                 return Err(LightningError{err: "Failed to find a sufficient route to the given destination".to_owned(), action: ErrorAction::IgnoreError});
 969         }
 970
 971         // Sort by total fees and take the best paths.
 972         payment_paths.sort_by_key(|path| path.get_total_fee_paid_msat());
 973         if payment_paths.len() > 50 {
 974                 payment_paths.truncate(50);
 975         }
 976
 977         // Draw multiple sufficient routes by randomly combining the selected paths.
 978         let mut drawn_routes = Vec::new();
 979         for i in 0..payment_paths.len() {
 980                 let mut cur_route = Vec::<PaymentPath>::new();
 981                 let mut aggregate_route_value_msat = 0;
 982
 983                 // Step (5).
 984                 // TODO: real random shuffle
 985                 // Currently just starts with i_th and goes up to i-1_th in a looped way.
 986                 let cur_payment_paths = [&payment_paths[i..], &payment_paths[..i]].concat();
 987
 988                 // Step (6).
 989                 for payment_path in cur_payment_paths {
 990                         cur_route.push(payment_path.clone());
 991                         aggregate_route_value_msat += payment_path.get_value_msat();
 992                         if aggregate_route_value_msat > final_value_msat {
 993                                 // Last path likely overpaid. Substract it from the most expensive
 994                                 // (in terms of proportional fee) path in this route and recompute fees.
 995                                 // This might be not the most economically efficient way, but fewer paths
 996                                 // also makes routing more reliable.
 997                                 let mut overpaid_value_msat = aggregate_route_value_msat - final_value_msat;
 998
 999                                 // First, drop some expensive low-value paths entirely if possible.
1000                                 // Sort by value so that we drop many really-low values first, since
1001                                 // fewer paths is better: the payment is less likely to fail.
1002                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1003                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1004                                 cur_route.sort_by_key(|path| path.get_value_msat());
1005                                 // We should make sure that at least 1 path left.
1006                                 let mut paths_left = cur_route.len();
1007                                 cur_route.retain(|path| {
1008                                         if paths_left == 1 {
1009                                                 return true
1010                                         }
1011                                         let mut keep = true;
1012                                         let path_value_msat = path.get_value_msat();
1013                                         if path_value_msat <= overpaid_value_msat {
1014                                                 keep = false;
1015                                                 overpaid_value_msat -= path_value_msat;
1016                                                 paths_left -= 1;
1017                                         }
1018                                         keep
1019                                 });
1020
1021                                 if overpaid_value_msat == 0 {
1022                                         break;
1023                                 }
1024
1025                                 assert!(cur_route.len() > 0);
1026
1027                                 // Step (7).
1028                                 // Now, substract the overpaid value from the most-expensive path.
1029                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1030                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1031                                 cur_route.sort_by_key(|path| { path.hops.iter().map(|hop| hop.channel_fees.proportional_millionths as u64).sum::<u64>() });
1032                                 let expensive_payment_path = cur_route.first_mut().unwrap();
1033                                 // We already dropped all the small channels above, meaning all the
1034                                 // remaining channels are larger than remaining overpaid_value_msat.
1035                                 // Thus, this can't be negative.
1036                                 let expensive_path_new_value_msat = expensive_payment_path.get_value_msat() - overpaid_value_msat;
1037                                 expensive_payment_path.update_value_and_recompute_fees(expensive_path_new_value_msat);
1038                                 break;
1039                         }
1040                 }
1041                 drawn_routes.push(cur_route);
1042         }
1043
1044         // Step (8).
1045         // Select the best route by lowest total fee.
1046         drawn_routes.sort_by_key(|paths| paths.iter().map(|path| path.get_total_fee_paid_msat()).sum::<u64>());
1047         let mut selected_paths = Vec::<Vec<RouteHop>>::new();
1048         for payment_path in drawn_routes.first().unwrap() {
1049                 selected_paths.push(payment_path.hops.iter().map(|payment_hop| payment_hop.route_hop.clone()).collect());
1050         }
1051
1052         if let Some(features) = &payee_features {
1053                 for path in selected_paths.iter_mut() {
1054                         path.last_mut().unwrap().node_features = features.to_context();
1055                 }
1056         }
1057
1058         let route = Route { paths: selected_paths };
1059         log_trace!(logger, "Got route: {}", log_route!(route));
1060         Ok(route)
1061 }
1062
1063 #[cfg(test)]
1064 mod tests {
1065         use routing::router::{get_route, RouteHint, RoutingFees};
1066         use routing::network_graph::{NetworkGraph, NetGraphMsgHandler};
1067         use ln::features::{ChannelFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
1068         use ln::msgs::{ErrorAction, LightningError, OptionalField, UnsignedChannelAnnouncement, ChannelAnnouncement, RoutingMessageHandler,
1069            NodeAnnouncement, UnsignedNodeAnnouncement, ChannelUpdate, UnsignedChannelUpdate};
1070         use ln::channelmanager;
1071         use util::test_utils;
1072         use util::ser::Writeable;
1073
1074         use bitcoin::hashes::sha256d::Hash as Sha256dHash;
1075         use bitcoin::hashes::Hash;
1076         use bitcoin::network::constants::Network;
1077         use bitcoin::blockdata::constants::genesis_block;
1078         use bitcoin::blockdata::script::Builder;
1079         use bitcoin::blockdata::opcodes;
1080         use bitcoin::blockdata::transaction::TxOut;
1081
1082         use hex;
1083
1084         use bitcoin::secp256k1::key::{PublicKey,SecretKey};
1085         use bitcoin::secp256k1::{Secp256k1, All};
1086
1087         use std::sync::Arc;
1088
1089         // Using the same keys for LN and BTC ids
1090         fn add_channel(net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>, secp_ctx: &Secp256k1<All>, node_1_privkey: &SecretKey,
1091            node_2_privkey: &SecretKey, features: ChannelFeatures, short_channel_id: u64) {
1092                 let node_id_1 = PublicKey::from_secret_key(&secp_ctx, node_1_privkey);
1093                 let node_id_2 = PublicKey::from_secret_key(&secp_ctx, node_2_privkey);
1094
1095                 let unsigned_announcement = UnsignedChannelAnnouncement {
1096                         features,
1097                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1098                         short_channel_id,
1099                         node_id_1,
1100                         node_id_2,
1101                         bitcoin_key_1: node_id_1,
1102                         bitcoin_key_2: node_id_2,
1103                         excess_data: Vec::new(),
1104                 };
1105
1106                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1107                 let valid_announcement = ChannelAnnouncement {
1108                         node_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1109                         node_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1110                         bitcoin_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1111                         bitcoin_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1112                         contents: unsigned_announcement.clone(),
1113                 };
1114                 match net_graph_msg_handler.handle_channel_announcement(&valid_announcement) {
1115                         Ok(res) => assert!(res),
1116                         _ => panic!()
1117                 };
1118         }
1119
1120         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) {
1121                 let msghash = hash_to_message!(&Sha256dHash::hash(&update.encode()[..])[..]);
1122                 let valid_channel_update = ChannelUpdate {
1123                         signature: secp_ctx.sign(&msghash, node_privkey),
1124                         contents: update.clone()
1125                 };
1126
1127                 match net_graph_msg_handler.handle_channel_update(&valid_channel_update) {
1128                         Ok(res) => assert!(res),
1129                         Err(_) => panic!()
1130                 };
1131         }
1132
1133         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,
1134            features: NodeFeatures, timestamp: u32) {
1135                 let node_id = PublicKey::from_secret_key(&secp_ctx, node_privkey);
1136                 let unsigned_announcement = UnsignedNodeAnnouncement {
1137                         features,
1138                         timestamp,
1139                         node_id,
1140                         rgb: [0; 3],
1141                         alias: [0; 32],
1142                         addresses: Vec::new(),
1143                         excess_address_data: Vec::new(),
1144                         excess_data: Vec::new(),
1145                 };
1146                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1147                 let valid_announcement = NodeAnnouncement {
1148                         signature: secp_ctx.sign(&msghash, node_privkey),
1149                         contents: unsigned_announcement.clone()
1150                 };
1151
1152                 match net_graph_msg_handler.handle_node_announcement(&valid_announcement) {
1153                         Ok(_) => (),
1154                         Err(_) => panic!()
1155                 };
1156         }
1157
1158         fn get_nodes(secp_ctx: &Secp256k1<All>) -> (SecretKey, PublicKey, Vec<SecretKey>, Vec<PublicKey>) {
1159                 let privkeys: Vec<SecretKey> = (2..10).map(|i| {
1160                         SecretKey::from_slice(&hex::decode(format!("{:02}", i).repeat(32)).unwrap()[..]).unwrap()
1161                 }).collect();
1162
1163                 let pubkeys = privkeys.iter().map(|secret| PublicKey::from_secret_key(&secp_ctx, secret)).collect();
1164
1165                 let our_privkey = SecretKey::from_slice(&hex::decode("01".repeat(32)).unwrap()[..]).unwrap();
1166                 let our_id = PublicKey::from_secret_key(&secp_ctx, &our_privkey);
1167
1168                 (our_privkey, our_id, privkeys, pubkeys)
1169         }
1170
1171         fn id_to_feature_flags(id: u8) -> Vec<u8> {
1172                 // Set the feature flags to the id'th odd (ie non-required) feature bit so that we can
1173                 // test for it later.
1174                 let idx = (id - 1) * 2 + 1;
1175                 if idx > 8*3 {
1176                         vec![1 << (idx - 8*3), 0, 0, 0]
1177                 } else if idx > 8*2 {
1178                         vec![1 << (idx - 8*2), 0, 0]
1179                 } else if idx > 8*1 {
1180                         vec![1 << (idx - 8*1), 0]
1181                 } else {
1182                         vec![1 << idx]
1183                 }
1184         }
1185
1186         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>) {
1187                 let secp_ctx = Secp256k1::new();
1188                 let logger = Arc::new(test_utils::TestLogger::new());
1189                 let chain_monitor = Arc::new(test_utils::TestChainSource::new(Network::Testnet));
1190                 let net_graph_msg_handler = NetGraphMsgHandler::new(genesis_block(Network::Testnet).header.block_hash(), None, Arc::clone(&logger));
1191                 // Build network from our_id to node7:
1192                 //
1193                 //        -1(1)2-  node0  -1(3)2-
1194                 //       /                       \
1195                 // our_id -1(12)2- node7 -1(13)2--- node2
1196                 //       \                       /
1197                 //        -1(2)2-  node1  -1(4)2-
1198                 //
1199                 //
1200                 // chan1  1-to-2: disabled
1201                 // chan1  2-to-1: enabled, 0 fee
1202                 //
1203                 // chan2  1-to-2: enabled, ignored fee
1204                 // chan2  2-to-1: enabled, 0 fee
1205                 //
1206                 // chan3  1-to-2: enabled, 0 fee
1207                 // chan3  2-to-1: enabled, 100 msat fee
1208                 //
1209                 // chan4  1-to-2: enabled, 100% fee
1210                 // chan4  2-to-1: enabled, 0 fee
1211                 //
1212                 // chan12 1-to-2: enabled, ignored fee
1213                 // chan12 2-to-1: enabled, 0 fee
1214                 //
1215                 // chan13 1-to-2: enabled, 200% fee
1216                 // chan13 2-to-1: enabled, 0 fee
1217                 //
1218                 //
1219                 //       -1(5)2- node3 -1(8)2--
1220                 //       |         2          |
1221                 //       |       (11)         |
1222                 //      /          1           \
1223                 // node2--1(6)2- node4 -1(9)2--- node6 (not in global route map)
1224                 //      \                      /
1225                 //       -1(7)2- node5 -1(10)2-
1226                 //
1227                 // chan5  1-to-2: enabled, 100 msat fee
1228                 // chan5  2-to-1: enabled, 0 fee
1229                 //
1230                 // chan6  1-to-2: enabled, 0 fee
1231                 // chan6  2-to-1: enabled, 0 fee
1232                 //
1233                 // chan7  1-to-2: enabled, 100% fee
1234                 // chan7  2-to-1: enabled, 0 fee
1235                 //
1236                 // chan8  1-to-2: enabled, variable fee (0 then 1000 msat)
1237                 // chan8  2-to-1: enabled, 0 fee
1238                 //
1239                 // chan9  1-to-2: enabled, 1001 msat fee
1240                 // chan9  2-to-1: enabled, 0 fee
1241                 //
1242                 // chan10 1-to-2: enabled, 0 fee
1243                 // chan10 2-to-1: enabled, 0 fee
1244                 //
1245                 // chan11 1-to-2: enabled, 0 fee
1246                 // chan11 2-to-1: enabled, 0 fee
1247
1248                 let (our_privkey, _, privkeys, _) = get_nodes(&secp_ctx);
1249
1250                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[0], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
1251                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1252                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1253                         short_channel_id: 1,
1254                         timestamp: 1,
1255                         flags: 1,
1256                         cltv_expiry_delta: 0,
1257                         htlc_minimum_msat: 0,
1258                         htlc_maximum_msat: OptionalField::Absent,
1259                         fee_base_msat: 0,
1260                         fee_proportional_millionths: 0,
1261                         excess_data: Vec::new()
1262                 });
1263
1264                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
1265
1266                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
1267                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1268                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1269                         short_channel_id: 2,
1270                         timestamp: 1,
1271                         flags: 0,
1272                         cltv_expiry_delta: u16::max_value(),
1273                         htlc_minimum_msat: 0,
1274                         htlc_maximum_msat: OptionalField::Absent,
1275                         fee_base_msat: u32::max_value(),
1276                         fee_proportional_millionths: u32::max_value(),
1277                         excess_data: Vec::new()
1278                 });
1279                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1280                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1281                         short_channel_id: 2,
1282                         timestamp: 1,
1283                         flags: 1,
1284                         cltv_expiry_delta: 0,
1285                         htlc_minimum_msat: 0,
1286                         htlc_maximum_msat: OptionalField::Absent,
1287                         fee_base_msat: 0,
1288                         fee_proportional_millionths: 0,
1289                         excess_data: Vec::new()
1290                 });
1291
1292                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
1293
1294                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[7], ChannelFeatures::from_le_bytes(id_to_feature_flags(12)), 12);
1295                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1296                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1297                         short_channel_id: 12,
1298                         timestamp: 1,
1299                         flags: 0,
1300                         cltv_expiry_delta: u16::max_value(),
1301                         htlc_minimum_msat: 0,
1302                         htlc_maximum_msat: OptionalField::Absent,
1303                         fee_base_msat: u32::max_value(),
1304                         fee_proportional_millionths: u32::max_value(),
1305                         excess_data: Vec::new()
1306                 });
1307                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1308                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1309                         short_channel_id: 12,
1310                         timestamp: 1,
1311                         flags: 1,
1312                         cltv_expiry_delta: 0,
1313                         htlc_minimum_msat: 0,
1314                         htlc_maximum_msat: OptionalField::Absent,
1315                         fee_base_msat: 0,
1316                         fee_proportional_millionths: 0,
1317                         excess_data: Vec::new()
1318                 });
1319
1320                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], NodeFeatures::from_le_bytes(id_to_feature_flags(8)), 0);
1321
1322                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
1323                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1324                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1325                         short_channel_id: 3,
1326                         timestamp: 1,
1327                         flags: 0,
1328                         cltv_expiry_delta: (3 << 8) | 1,
1329                         htlc_minimum_msat: 0,
1330                         htlc_maximum_msat: OptionalField::Absent,
1331                         fee_base_msat: 0,
1332                         fee_proportional_millionths: 0,
1333                         excess_data: Vec::new()
1334                 });
1335                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1336                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1337                         short_channel_id: 3,
1338                         timestamp: 1,
1339                         flags: 1,
1340                         cltv_expiry_delta: (3 << 8) | 2,
1341                         htlc_minimum_msat: 0,
1342                         htlc_maximum_msat: OptionalField::Absent,
1343                         fee_base_msat: 100,
1344                         fee_proportional_millionths: 0,
1345                         excess_data: Vec::new()
1346                 });
1347
1348                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
1349                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1350                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1351                         short_channel_id: 4,
1352                         timestamp: 1,
1353                         flags: 0,
1354                         cltv_expiry_delta: (4 << 8) | 1,
1355                         htlc_minimum_msat: 0,
1356                         htlc_maximum_msat: OptionalField::Absent,
1357                         fee_base_msat: 0,
1358                         fee_proportional_millionths: 1000000,
1359                         excess_data: Vec::new()
1360                 });
1361                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1362                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1363                         short_channel_id: 4,
1364                         timestamp: 1,
1365                         flags: 1,
1366                         cltv_expiry_delta: (4 << 8) | 2,
1367                         htlc_minimum_msat: 0,
1368                         htlc_maximum_msat: OptionalField::Absent,
1369                         fee_base_msat: 0,
1370                         fee_proportional_millionths: 0,
1371                         excess_data: Vec::new()
1372                 });
1373
1374                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(13)), 13);
1375                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1376                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1377                         short_channel_id: 13,
1378                         timestamp: 1,
1379                         flags: 0,
1380                         cltv_expiry_delta: (13 << 8) | 1,
1381                         htlc_minimum_msat: 0,
1382                         htlc_maximum_msat: OptionalField::Absent,
1383                         fee_base_msat: 0,
1384                         fee_proportional_millionths: 2000000,
1385                         excess_data: Vec::new()
1386                 });
1387                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1388                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1389                         short_channel_id: 13,
1390                         timestamp: 1,
1391                         flags: 1,
1392                         cltv_expiry_delta: (13 << 8) | 2,
1393                         htlc_minimum_msat: 0,
1394                         htlc_maximum_msat: OptionalField::Absent,
1395                         fee_base_msat: 0,
1396                         fee_proportional_millionths: 0,
1397                         excess_data: Vec::new()
1398                 });
1399
1400                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
1401
1402                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
1403                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1404                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1405                         short_channel_id: 6,
1406                         timestamp: 1,
1407                         flags: 0,
1408                         cltv_expiry_delta: (6 << 8) | 1,
1409                         htlc_minimum_msat: 0,
1410                         htlc_maximum_msat: OptionalField::Absent,
1411                         fee_base_msat: 0,
1412                         fee_proportional_millionths: 0,
1413                         excess_data: Vec::new()
1414                 });
1415                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1416                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1417                         short_channel_id: 6,
1418                         timestamp: 1,
1419                         flags: 1,
1420                         cltv_expiry_delta: (6 << 8) | 2,
1421                         htlc_minimum_msat: 0,
1422                         htlc_maximum_msat: OptionalField::Absent,
1423                         fee_base_msat: 0,
1424                         fee_proportional_millionths: 0,
1425                         excess_data: Vec::new(),
1426                 });
1427
1428                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(11)), 11);
1429                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1430                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1431                         short_channel_id: 11,
1432                         timestamp: 1,
1433                         flags: 0,
1434                         cltv_expiry_delta: (11 << 8) | 1,
1435                         htlc_minimum_msat: 0,
1436                         htlc_maximum_msat: OptionalField::Absent,
1437                         fee_base_msat: 0,
1438                         fee_proportional_millionths: 0,
1439                         excess_data: Vec::new()
1440                 });
1441                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
1442                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1443                         short_channel_id: 11,
1444                         timestamp: 1,
1445                         flags: 1,
1446                         cltv_expiry_delta: (11 << 8) | 2,
1447                         htlc_minimum_msat: 0,
1448                         htlc_maximum_msat: OptionalField::Absent,
1449                         fee_base_msat: 0,
1450                         fee_proportional_millionths: 0,
1451                         excess_data: Vec::new()
1452                 });
1453
1454                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(5)), 0);
1455
1456                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
1457
1458                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[5], ChannelFeatures::from_le_bytes(id_to_feature_flags(7)), 7);
1459                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1460                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1461                         short_channel_id: 7,
1462                         timestamp: 1,
1463                         flags: 0,
1464                         cltv_expiry_delta: (7 << 8) | 1,
1465                         htlc_minimum_msat: 0,
1466                         htlc_maximum_msat: OptionalField::Absent,
1467                         fee_base_msat: 0,
1468                         fee_proportional_millionths: 1000000,
1469                         excess_data: Vec::new()
1470                 });
1471                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[5], UnsignedChannelUpdate {
1472                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1473                         short_channel_id: 7,
1474                         timestamp: 1,
1475                         flags: 1,
1476                         cltv_expiry_delta: (7 << 8) | 2,
1477                         htlc_minimum_msat: 0,
1478                         htlc_maximum_msat: OptionalField::Absent,
1479                         fee_base_msat: 0,
1480                         fee_proportional_millionths: 0,
1481                         excess_data: Vec::new()
1482                 });
1483
1484                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[5], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
1485
1486                 (secp_ctx, net_graph_msg_handler, chain_monitor, logger)
1487         }
1488
1489         #[test]
1490         fn simple_route_test() {
1491                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1492                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1493
1494                 // Simple route to 2 via 1
1495
1496                 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)) {
1497                         assert_eq!(err, "Cannot send a payment of 0 msat");
1498                 } else { panic!(); }
1499
1500                 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();
1501                 assert_eq!(route.paths[0].len(), 2);
1502
1503                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
1504                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1505                 assert_eq!(route.paths[0][0].fee_msat, 100);
1506                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
1507                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
1508                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
1509
1510                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1511                 assert_eq!(route.paths[0][1].short_channel_id, 4);
1512                 assert_eq!(route.paths[0][1].fee_msat, 100);
1513                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1514                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1515                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
1516         }
1517
1518         #[test]
1519         fn invalid_first_hop_test() {
1520                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1521                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1522
1523                 // Simple route to 2 via 1
1524
1525                 let our_chans = vec![channelmanager::ChannelDetails {
1526                         channel_id: [0; 32],
1527                         short_channel_id: Some(2),
1528                         remote_network_id: our_id,
1529                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1530                         channel_value_satoshis: 100000,
1531                         user_id: 0,
1532                         outbound_capacity_msat: 100000,
1533                         inbound_capacity_msat: 100000,
1534                         is_live: true,
1535                         counterparty_forwarding_info: None,
1536                 }];
1537
1538                 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)) {
1539                         assert_eq!(err, "First hop cannot have our_node_id as a destination.");
1540                 } else { panic!(); }
1541
1542                 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();
1543                 assert_eq!(route.paths[0].len(), 2);
1544         }
1545
1546         #[test]
1547         fn htlc_minimum_test() {
1548                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1549                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1550
1551                 // Simple route to 2 via 1
1552
1553                 // Disable other paths
1554                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1555                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1556                         short_channel_id: 12,
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[0], UnsignedChannelUpdate {
1567                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1568                         short_channel_id: 3,
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[7], UnsignedChannelUpdate {
1579                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1580                         short_channel_id: 13,
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                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1591                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1592                         short_channel_id: 6,
1593                         timestamp: 2,
1594                         flags: 2, // to disable
1595                         cltv_expiry_delta: 0,
1596                         htlc_minimum_msat: 0,
1597                         htlc_maximum_msat: OptionalField::Absent,
1598                         fee_base_msat: 0,
1599                         fee_proportional_millionths: 0,
1600                         excess_data: Vec::new()
1601                 });
1602                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1603                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1604                         short_channel_id: 7,
1605                         timestamp: 2,
1606                         flags: 2, // to disable
1607                         cltv_expiry_delta: 0,
1608                         htlc_minimum_msat: 0,
1609                         htlc_maximum_msat: OptionalField::Absent,
1610                         fee_base_msat: 0,
1611                         fee_proportional_millionths: 0,
1612                         excess_data: Vec::new()
1613                 });
1614
1615                 // Check against amount_to_transfer_over_msat.
1616                 // Set minimal HTLC of 200_000_000 msat.
1617                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1618                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1619                         short_channel_id: 2,
1620                         timestamp: 3,
1621                         flags: 0,
1622                         cltv_expiry_delta: 0,
1623                         htlc_minimum_msat: 200_000_000,
1624                         htlc_maximum_msat: OptionalField::Absent,
1625                         fee_base_msat: 0,
1626                         fee_proportional_millionths: 0,
1627                         excess_data: Vec::new()
1628                 });
1629
1630                 // Second hop only allows to forward 199_999_999 at most, thus not allowing the first hop to
1631                 // be used.
1632                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1633                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1634                         short_channel_id: 4,
1635                         timestamp: 3,
1636                         flags: 0,
1637                         cltv_expiry_delta: 0,
1638                         htlc_minimum_msat: 0,
1639                         htlc_maximum_msat: OptionalField::Present(199_999_999),
1640                         fee_base_msat: 0,
1641                         fee_proportional_millionths: 0,
1642                         excess_data: Vec::new()
1643                 });
1644
1645                 // Not possible to send 199_999_999, because the minimum on channel=2 is 200_000_000.
1646                 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)) {
1647                         assert_eq!(err, "Failed to find a path to the given destination");
1648                 } else { panic!(); }
1649
1650                 // Lift the restriction on the first hop.
1651                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1652                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1653                         short_channel_id: 2,
1654                         timestamp: 4,
1655                         flags: 0,
1656                         cltv_expiry_delta: 0,
1657                         htlc_minimum_msat: 0,
1658                         htlc_maximum_msat: OptionalField::Absent,
1659                         fee_base_msat: 0,
1660                         fee_proportional_millionths: 0,
1661                         excess_data: Vec::new()
1662                 });
1663
1664                 // A payment above the minimum should pass
1665                 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();
1666                 assert_eq!(route.paths[0].len(), 2);
1667         }
1668
1669         #[test]
1670         fn htlc_minimum_overpay_test() {
1671                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1672                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1673
1674                 // A route to node#2 via two paths.
1675                 // One path allows transferring 35-40 sats, another one also allows 35-40 sats.
1676                 // Thus, they can't send 60 without overpaying.
1677                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1678                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1679                         short_channel_id: 2,
1680                         timestamp: 2,
1681                         flags: 0,
1682                         cltv_expiry_delta: 0,
1683                         htlc_minimum_msat: 35_000,
1684                         htlc_maximum_msat: OptionalField::Present(40_000),
1685                         fee_base_msat: 0,
1686                         fee_proportional_millionths: 0,
1687                         excess_data: Vec::new()
1688                 });
1689                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1690                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1691                         short_channel_id: 12,
1692                         timestamp: 3,
1693                         flags: 0,
1694                         cltv_expiry_delta: 0,
1695                         htlc_minimum_msat: 35_000,
1696                         htlc_maximum_msat: OptionalField::Present(40_000),
1697                         fee_base_msat: 0,
1698                         fee_proportional_millionths: 0,
1699                         excess_data: Vec::new()
1700                 });
1701
1702                 // Make 0 fee.
1703                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1704                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1705                         short_channel_id: 13,
1706                         timestamp: 2,
1707                         flags: 0,
1708                         cltv_expiry_delta: 0,
1709                         htlc_minimum_msat: 0,
1710                         htlc_maximum_msat: OptionalField::Absent,
1711                         fee_base_msat: 0,
1712                         fee_proportional_millionths: 0,
1713                         excess_data: Vec::new()
1714                 });
1715                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1716                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1717                         short_channel_id: 4,
1718                         timestamp: 2,
1719                         flags: 0,
1720                         cltv_expiry_delta: 0,
1721                         htlc_minimum_msat: 0,
1722                         htlc_maximum_msat: OptionalField::Absent,
1723                         fee_base_msat: 0,
1724                         fee_proportional_millionths: 0,
1725                         excess_data: Vec::new()
1726                 });
1727
1728                 // Disable other paths
1729                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1730                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1731                         short_channel_id: 1,
1732                         timestamp: 3,
1733                         flags: 2, // to disable
1734                         cltv_expiry_delta: 0,
1735                         htlc_minimum_msat: 0,
1736                         htlc_maximum_msat: OptionalField::Absent,
1737                         fee_base_msat: 0,
1738                         fee_proportional_millionths: 0,
1739                         excess_data: Vec::new()
1740                 });
1741
1742                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1743                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)).unwrap();
1744                 // Overpay fees to hit htlc_minimum_msat.
1745                 let overpaid_fees = route.paths[0][0].fee_msat + route.paths[1][0].fee_msat;
1746                 // TODO: this could be better balanced to overpay 10k and not 15k.
1747                 assert_eq!(overpaid_fees, 15_000);
1748
1749                 // Now, test that if there are 2 paths, a "cheaper" by fee path wouldn't be prioritized
1750                 // while taking even more fee to match htlc_minimum_msat.
1751                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1752                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1753                         short_channel_id: 12,
1754                         timestamp: 4,
1755                         flags: 0,
1756                         cltv_expiry_delta: 0,
1757                         htlc_minimum_msat: 65_000,
1758                         htlc_maximum_msat: OptionalField::Present(80_000),
1759                         fee_base_msat: 0,
1760                         fee_proportional_millionths: 0,
1761                         excess_data: Vec::new()
1762                 });
1763                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1764                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1765                         short_channel_id: 2,
1766                         timestamp: 3,
1767                         flags: 0,
1768                         cltv_expiry_delta: 0,
1769                         htlc_minimum_msat: 0,
1770                         htlc_maximum_msat: OptionalField::Absent,
1771                         fee_base_msat: 0,
1772                         fee_proportional_millionths: 0,
1773                         excess_data: Vec::new()
1774                 });
1775                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1776                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1777                         short_channel_id: 4,
1778                         timestamp: 4,
1779                         flags: 0,
1780                         cltv_expiry_delta: 0,
1781                         htlc_minimum_msat: 0,
1782                         htlc_maximum_msat: OptionalField::Absent,
1783                         fee_base_msat: 0,
1784                         fee_proportional_millionths: 100_000,
1785                         excess_data: Vec::new()
1786                 });
1787
1788                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1789                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)).unwrap();
1790                 // Fine to overpay for htlc_minimum_msat if it allows us to save fee.
1791                 assert_eq!(route.paths.len(), 1);
1792                 assert_eq!(route.paths[0][0].short_channel_id, 12);
1793                 let fees = route.paths[0][0].fee_msat;
1794                 assert_eq!(fees, 5_000);
1795
1796                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1797                         Some(InvoiceFeatures::known()), None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
1798                 // Not fine to overpay for htlc_minimum_msat if it requires paying more than fee on
1799                 // the other channel.
1800                 assert_eq!(route.paths.len(), 1);
1801                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1802                 let fees = route.paths[0][0].fee_msat;
1803                 assert_eq!(fees, 5_000);
1804         }
1805
1806         #[test]
1807         fn disable_channels_test() {
1808                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1809                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1810
1811                 // // Disable channels 4 and 12 by flags=2
1812                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1813                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1814                         short_channel_id: 4,
1815                         timestamp: 2,
1816                         flags: 2, // to disable
1817                         cltv_expiry_delta: 0,
1818                         htlc_minimum_msat: 0,
1819                         htlc_maximum_msat: OptionalField::Absent,
1820                         fee_base_msat: 0,
1821                         fee_proportional_millionths: 0,
1822                         excess_data: Vec::new()
1823                 });
1824                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1825                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1826                         short_channel_id: 12,
1827                         timestamp: 2,
1828                         flags: 2, // to disable
1829                         cltv_expiry_delta: 0,
1830                         htlc_minimum_msat: 0,
1831                         htlc_maximum_msat: OptionalField::Absent,
1832                         fee_base_msat: 0,
1833                         fee_proportional_millionths: 0,
1834                         excess_data: Vec::new()
1835                 });
1836
1837                 // If all the channels require some features we don't understand, route should fail
1838                 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)) {
1839                         assert_eq!(err, "Failed to find a path to the given destination");
1840                 } else { panic!(); }
1841
1842                 // If we specify a channel to node7, that overrides our local channel view and that gets used
1843                 let our_chans = vec![channelmanager::ChannelDetails {
1844                         channel_id: [0; 32],
1845                         short_channel_id: Some(42),
1846                         remote_network_id: nodes[7].clone(),
1847                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1848                         channel_value_satoshis: 0,
1849                         user_id: 0,
1850                         outbound_capacity_msat: 250_000_000,
1851                         inbound_capacity_msat: 0,
1852                         is_live: true,
1853                         counterparty_forwarding_info: None,
1854                 }];
1855                 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();
1856                 assert_eq!(route.paths[0].len(), 2);
1857
1858                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
1859                 assert_eq!(route.paths[0][0].short_channel_id, 42);
1860                 assert_eq!(route.paths[0][0].fee_msat, 200);
1861                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
1862                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
1863                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
1864
1865                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1866                 assert_eq!(route.paths[0][1].short_channel_id, 13);
1867                 assert_eq!(route.paths[0][1].fee_msat, 100);
1868                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1869                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1870                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
1871         }
1872
1873         #[test]
1874         fn disable_node_test() {
1875                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1876                 let (_, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1877
1878                 // Disable nodes 1, 2, and 8 by requiring unknown feature bits
1879                 let mut unknown_features = NodeFeatures::known();
1880                 unknown_features.set_required_unknown_bits();
1881                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], unknown_features.clone(), 1);
1882                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], unknown_features.clone(), 1);
1883                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], unknown_features.clone(), 1);
1884
1885                 // If all nodes require some features we don't understand, route should fail
1886                 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)) {
1887                         assert_eq!(err, "Failed to find a path to the given destination");
1888                 } else { panic!(); }
1889
1890                 // If we specify a channel to node7, that overrides our local channel view and that gets used
1891                 let our_chans = vec![channelmanager::ChannelDetails {
1892                         channel_id: [0; 32],
1893                         short_channel_id: Some(42),
1894                         remote_network_id: nodes[7].clone(),
1895                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1896                         channel_value_satoshis: 0,
1897                         user_id: 0,
1898                         outbound_capacity_msat: 250_000_000,
1899                         inbound_capacity_msat: 0,
1900                         is_live: true,
1901                         counterparty_forwarding_info: None,
1902                 }];
1903                 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();
1904                 assert_eq!(route.paths[0].len(), 2);
1905
1906                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
1907                 assert_eq!(route.paths[0][0].short_channel_id, 42);
1908                 assert_eq!(route.paths[0][0].fee_msat, 200);
1909                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
1910                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
1911                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
1912
1913                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1914                 assert_eq!(route.paths[0][1].short_channel_id, 13);
1915                 assert_eq!(route.paths[0][1].fee_msat, 100);
1916                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1917                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1918                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
1919
1920                 // Note that we don't test disabling node 3 and failing to route to it, as we (somewhat
1921                 // naively) assume that the user checked the feature bits on the invoice, which override
1922                 // the node_announcement.
1923         }
1924
1925         #[test]
1926         fn our_chans_test() {
1927                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1928                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1929
1930                 // Route to 1 via 2 and 3 because our channel to 1 is disabled
1931                 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();
1932                 assert_eq!(route.paths[0].len(), 3);
1933
1934                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
1935                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1936                 assert_eq!(route.paths[0][0].fee_msat, 200);
1937                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
1938                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
1939                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
1940
1941                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1942                 assert_eq!(route.paths[0][1].short_channel_id, 4);
1943                 assert_eq!(route.paths[0][1].fee_msat, 100);
1944                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (3 << 8) | 2);
1945                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1946                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
1947
1948                 assert_eq!(route.paths[0][2].pubkey, nodes[0]);
1949                 assert_eq!(route.paths[0][2].short_channel_id, 3);
1950                 assert_eq!(route.paths[0][2].fee_msat, 100);
1951                 assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
1952                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(1));
1953                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(3));
1954
1955                 // If we specify a channel to node7, that overrides our local channel view and that gets used
1956                 let our_chans = vec![channelmanager::ChannelDetails {
1957                         channel_id: [0; 32],
1958                         short_channel_id: Some(42),
1959                         remote_network_id: nodes[7].clone(),
1960                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1961                         channel_value_satoshis: 0,
1962                         user_id: 0,
1963                         outbound_capacity_msat: 250_000_000,
1964                         inbound_capacity_msat: 0,
1965                         is_live: true,
1966                         counterparty_forwarding_info: None,
1967                 }];
1968                 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();
1969                 assert_eq!(route.paths[0].len(), 2);
1970
1971                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
1972                 assert_eq!(route.paths[0][0].short_channel_id, 42);
1973                 assert_eq!(route.paths[0][0].fee_msat, 200);
1974                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
1975                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
1976                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
1977
1978                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1979                 assert_eq!(route.paths[0][1].short_channel_id, 13);
1980                 assert_eq!(route.paths[0][1].fee_msat, 100);
1981                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1982                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1983                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
1984         }
1985
1986         fn last_hops(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
1987                 let zero_fees = RoutingFees {
1988                         base_msat: 0,
1989                         proportional_millionths: 0,
1990                 };
1991                 vec!(RouteHint {
1992                         src_node_id: nodes[3].clone(),
1993                         short_channel_id: 8,
1994                         fees: zero_fees,
1995                         cltv_expiry_delta: (8 << 8) | 1,
1996                         htlc_minimum_msat: None,
1997                         htlc_maximum_msat: None,
1998                 }, RouteHint {
1999                         src_node_id: nodes[4].clone(),
2000                         short_channel_id: 9,
2001                         fees: RoutingFees {
2002                                 base_msat: 1001,
2003                                 proportional_millionths: 0,
2004                         },
2005                         cltv_expiry_delta: (9 << 8) | 1,
2006                         htlc_minimum_msat: None,
2007                         htlc_maximum_msat: None,
2008                 }, RouteHint {
2009                         src_node_id: nodes[5].clone(),
2010                         short_channel_id: 10,
2011                         fees: zero_fees,
2012                         cltv_expiry_delta: (10 << 8) | 1,
2013                         htlc_minimum_msat: None,
2014                         htlc_maximum_msat: None,
2015                 })
2016         }
2017
2018         #[test]
2019         fn last_hops_test() {
2020                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2021                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2022
2023                 // Simple test across 2, 3, 5, and 4 via a last_hop channel
2024
2025                 // First check that lst hop can't have its source as the payee.
2026                 let invalid_last_hop = RouteHint {
2027                         src_node_id: nodes[6],
2028                         short_channel_id: 8,
2029                         fees: RoutingFees {
2030                                 base_msat: 1000,
2031                                 proportional_millionths: 0,
2032                         },
2033                         cltv_expiry_delta: (8 << 8) | 1,
2034                         htlc_minimum_msat: None,
2035                         htlc_maximum_msat: None,
2036                 };
2037
2038                 let mut invalid_last_hops = last_hops(&nodes);
2039                 invalid_last_hops.push(invalid_last_hop);
2040                 {
2041                         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)) {
2042                                 assert_eq!(err, "Last hop cannot have a payee as a source.");
2043                         } else { panic!(); }
2044                 }
2045
2046                 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();
2047                 assert_eq!(route.paths[0].len(), 5);
2048
2049                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2050                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2051                 assert_eq!(route.paths[0][0].fee_msat, 100);
2052                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2053                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2054                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2055
2056                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2057                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2058                 assert_eq!(route.paths[0][1].fee_msat, 0);
2059                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2060                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2061                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2062
2063                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2064                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2065                 assert_eq!(route.paths[0][2].fee_msat, 0);
2066                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2067                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2068                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2069
2070                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2071                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2072                 assert_eq!(route.paths[0][3].fee_msat, 0);
2073                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2074                 // If we have a peer in the node map, we'll use their features here since we don't have
2075                 // a way of figuring out their features from the invoice:
2076                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2077                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2078
2079                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2080                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2081                 assert_eq!(route.paths[0][4].fee_msat, 100);
2082                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2083                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2084                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2085         }
2086
2087         #[test]
2088         fn our_chans_last_hop_connect_test() {
2089                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2090                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2091
2092                 // Simple test with outbound channel to 4 to test that last_hops and first_hops connect
2093                 let our_chans = vec![channelmanager::ChannelDetails {
2094                         channel_id: [0; 32],
2095                         short_channel_id: Some(42),
2096                         remote_network_id: nodes[3].clone(),
2097                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2098                         channel_value_satoshis: 0,
2099                         user_id: 0,
2100                         outbound_capacity_msat: 250_000_000,
2101                         inbound_capacity_msat: 0,
2102                         is_live: true,
2103                         counterparty_forwarding_info: None,
2104                 }];
2105                 let mut last_hops = last_hops(&nodes);
2106                 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();
2107                 assert_eq!(route.paths[0].len(), 2);
2108
2109                 assert_eq!(route.paths[0][0].pubkey, nodes[3]);
2110                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2111                 assert_eq!(route.paths[0][0].fee_msat, 0);
2112                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2113                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2114                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2115
2116                 assert_eq!(route.paths[0][1].pubkey, nodes[6]);
2117                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2118                 assert_eq!(route.paths[0][1].fee_msat, 100);
2119                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2120                 assert_eq!(route.paths[0][1].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2121                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2122
2123                 last_hops[0].fees.base_msat = 1000;
2124
2125                 // Revert to via 6 as the fee on 8 goes up
2126                 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();
2127                 assert_eq!(route.paths[0].len(), 4);
2128
2129                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2130                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2131                 assert_eq!(route.paths[0][0].fee_msat, 200); // fee increased as its % of value transferred across node
2132                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2133                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2134                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2135
2136                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2137                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2138                 assert_eq!(route.paths[0][1].fee_msat, 100);
2139                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (7 << 8) | 1);
2140                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2141                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2142
2143                 assert_eq!(route.paths[0][2].pubkey, nodes[5]);
2144                 assert_eq!(route.paths[0][2].short_channel_id, 7);
2145                 assert_eq!(route.paths[0][2].fee_msat, 0);
2146                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (10 << 8) | 1);
2147                 // If we have a peer in the node map, we'll use their features here since we don't have
2148                 // a way of figuring out their features from the invoice:
2149                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
2150                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(7));
2151
2152                 assert_eq!(route.paths[0][3].pubkey, nodes[6]);
2153                 assert_eq!(route.paths[0][3].short_channel_id, 10);
2154                 assert_eq!(route.paths[0][3].fee_msat, 100);
2155                 assert_eq!(route.paths[0][3].cltv_expiry_delta, 42);
2156                 assert_eq!(route.paths[0][3].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2157                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2158
2159                 // ...but still use 8 for larger payments as 6 has a variable feerate
2160                 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();
2161                 assert_eq!(route.paths[0].len(), 5);
2162
2163                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2164                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2165                 assert_eq!(route.paths[0][0].fee_msat, 3000);
2166                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2167                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2168                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2169
2170                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2171                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2172                 assert_eq!(route.paths[0][1].fee_msat, 0);
2173                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2174                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2175                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2176
2177                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2178                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2179                 assert_eq!(route.paths[0][2].fee_msat, 0);
2180                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2181                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2182                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2183
2184                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2185                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2186                 assert_eq!(route.paths[0][3].fee_msat, 1000);
2187                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2188                 // If we have a peer in the node map, we'll use their features here since we don't have
2189                 // a way of figuring out their features from the invoice:
2190                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2191                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2192
2193                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2194                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2195                 assert_eq!(route.paths[0][4].fee_msat, 2000);
2196                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2197                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2198                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2199         }
2200
2201         #[test]
2202         fn unannounced_path_test() {
2203                 // We should be able to send a payment to a destination without any help of a routing graph
2204                 // if we have a channel with a common counterparty that appears in the first and last hop
2205                 // hints.
2206                 let source_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 41).repeat(32)).unwrap()[..]).unwrap());
2207                 let middle_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 42).repeat(32)).unwrap()[..]).unwrap());
2208                 let target_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 43).repeat(32)).unwrap()[..]).unwrap());
2209
2210                 // If we specify a channel to a middle hop, that overrides our local channel view and that gets used
2211                 let last_hops = vec![RouteHint {
2212                         src_node_id: middle_node_id,
2213                         short_channel_id: 8,
2214                         fees: RoutingFees {
2215                                 base_msat: 1000,
2216                                 proportional_millionths: 0,
2217                         },
2218                         cltv_expiry_delta: (8 << 8) | 1,
2219                         htlc_minimum_msat: None,
2220                         htlc_maximum_msat: None,
2221                 }];
2222                 let our_chans = vec![channelmanager::ChannelDetails {
2223                         channel_id: [0; 32],
2224                         short_channel_id: Some(42),
2225                         remote_network_id: middle_node_id,
2226                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2227                         channel_value_satoshis: 100000,
2228                         user_id: 0,
2229                         outbound_capacity_msat: 100000,
2230                         inbound_capacity_msat: 100000,
2231                         is_live: true,
2232                         counterparty_forwarding_info: None,
2233                 }];
2234                 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();
2235
2236                 assert_eq!(route.paths[0].len(), 2);
2237
2238                 assert_eq!(route.paths[0][0].pubkey, middle_node_id);
2239                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2240                 assert_eq!(route.paths[0][0].fee_msat, 1000);
2241                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2242                 assert_eq!(route.paths[0][0].node_features.le_flags(), &[0b11]);
2243                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2244
2245                 assert_eq!(route.paths[0][1].pubkey, target_node_id);
2246                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2247                 assert_eq!(route.paths[0][1].fee_msat, 100);
2248                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2249                 assert_eq!(route.paths[0][1].node_features.le_flags(), &[0; 0]); // We dont pass flags in from invoices yet
2250                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2251         }
2252
2253         #[test]
2254         fn available_amount_while_routing_test() {
2255                 // Tests whether we choose the correct available channel amount while routing.
2256
2257                 let (secp_ctx, mut net_graph_msg_handler, chain_monitor, logger) = build_graph();
2258                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2259
2260                 // We will use a simple single-path route from
2261                 // our node to node2 via node0: channels {1, 3}.
2262
2263                 // First disable all other paths.
2264                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2265                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2266                         short_channel_id: 2,
2267                         timestamp: 2,
2268                         flags: 2,
2269                         cltv_expiry_delta: 0,
2270                         htlc_minimum_msat: 0,
2271                         htlc_maximum_msat: OptionalField::Present(100_000),
2272                         fee_base_msat: 0,
2273                         fee_proportional_millionths: 0,
2274                         excess_data: Vec::new()
2275                 });
2276                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2277                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2278                         short_channel_id: 12,
2279                         timestamp: 2,
2280                         flags: 2,
2281                         cltv_expiry_delta: 0,
2282                         htlc_minimum_msat: 0,
2283                         htlc_maximum_msat: OptionalField::Present(100_000),
2284                         fee_base_msat: 0,
2285                         fee_proportional_millionths: 0,
2286                         excess_data: Vec::new()
2287                 });
2288
2289                 // Make the first channel (#1) very permissive,
2290                 // and we will be testing all limits on the second channel.
2291                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2292                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2293                         short_channel_id: 1,
2294                         timestamp: 2,
2295                         flags: 0,
2296                         cltv_expiry_delta: 0,
2297                         htlc_minimum_msat: 0,
2298                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2299                         fee_base_msat: 0,
2300                         fee_proportional_millionths: 0,
2301                         excess_data: Vec::new()
2302                 });
2303
2304                 // First, let's see if routing works if we have absolutely no idea about the available amount.
2305                 // In this case, it should be set to 250_000 sats.
2306                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2307                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2308                         short_channel_id: 3,
2309                         timestamp: 2,
2310                         flags: 0,
2311                         cltv_expiry_delta: 0,
2312                         htlc_minimum_msat: 0,
2313                         htlc_maximum_msat: OptionalField::Absent,
2314                         fee_base_msat: 0,
2315                         fee_proportional_millionths: 0,
2316                         excess_data: Vec::new()
2317                 });
2318
2319                 {
2320                         // Attempt to route more than available results in a failure.
2321                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2322                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000_001, 42, Arc::clone(&logger)) {
2323                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2324                         } else { panic!(); }
2325                 }
2326
2327                 {
2328                         // Now, attempt to route an exact amount we have should be fine.
2329                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2330                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000_000, 42, Arc::clone(&logger)).unwrap();
2331                         assert_eq!(route.paths.len(), 1);
2332                         let path = route.paths.last().unwrap();
2333                         assert_eq!(path.len(), 2);
2334                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2335                         assert_eq!(path.last().unwrap().fee_msat, 250_000_000);
2336                 }
2337
2338                 // Check that setting outbound_capacity_msat in first_hops limits the channels.
2339                 // Disable channel #1 and use another first hop.
2340                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2341                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2342                         short_channel_id: 1,
2343                         timestamp: 3,
2344                         flags: 2,
2345                         cltv_expiry_delta: 0,
2346                         htlc_minimum_msat: 0,
2347                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2348                         fee_base_msat: 0,
2349                         fee_proportional_millionths: 0,
2350                         excess_data: Vec::new()
2351                 });
2352
2353                 // Now, limit the first_hop by the outbound_capacity_msat of 200_000 sats.
2354                 let our_chans = vec![channelmanager::ChannelDetails {
2355                         channel_id: [0; 32],
2356                         short_channel_id: Some(42),
2357                         remote_network_id: nodes[0].clone(),
2358                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2359                         channel_value_satoshis: 0,
2360                         user_id: 0,
2361                         outbound_capacity_msat: 200_000_000,
2362                         inbound_capacity_msat: 0,
2363                         is_live: true,
2364                         counterparty_forwarding_info: None,
2365                 }];
2366
2367                 {
2368                         // Attempt to route more than available results in a failure.
2369                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2370                                         Some(InvoiceFeatures::known()), Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_001, 42, Arc::clone(&logger)) {
2371                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2372                         } else { panic!(); }
2373                 }
2374
2375                 {
2376                         // Now, attempt to route an exact amount we have should be fine.
2377                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2378                                 Some(InvoiceFeatures::known()), Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_000, 42, Arc::clone(&logger)).unwrap();
2379                         assert_eq!(route.paths.len(), 1);
2380                         let path = route.paths.last().unwrap();
2381                         assert_eq!(path.len(), 2);
2382                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2383                         assert_eq!(path.last().unwrap().fee_msat, 200_000_000);
2384                 }
2385
2386                 // Enable channel #1 back.
2387                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2388                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2389                         short_channel_id: 1,
2390                         timestamp: 4,
2391                         flags: 0,
2392                         cltv_expiry_delta: 0,
2393                         htlc_minimum_msat: 0,
2394                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2395                         fee_base_msat: 0,
2396                         fee_proportional_millionths: 0,
2397                         excess_data: Vec::new()
2398                 });
2399
2400
2401                 // Now let's see if routing works if we know only htlc_maximum_msat.
2402                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2403                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2404                         short_channel_id: 3,
2405                         timestamp: 3,
2406                         flags: 0,
2407                         cltv_expiry_delta: 0,
2408                         htlc_minimum_msat: 0,
2409                         htlc_maximum_msat: OptionalField::Present(15_000),
2410                         fee_base_msat: 0,
2411                         fee_proportional_millionths: 0,
2412                         excess_data: Vec::new()
2413                 });
2414
2415                 {
2416                         // Attempt to route more than available results in a failure.
2417                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2418                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 15_001, 42, Arc::clone(&logger)) {
2419                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2420                         } else { panic!(); }
2421                 }
2422
2423                 {
2424                         // Now, attempt to route an exact amount we have should be fine.
2425                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2426                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 15_000, 42, Arc::clone(&logger)).unwrap();
2427                         assert_eq!(route.paths.len(), 1);
2428                         let path = route.paths.last().unwrap();
2429                         assert_eq!(path.len(), 2);
2430                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2431                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
2432                 }
2433
2434                 // Now let's see if routing works if we know only capacity from the UTXO.
2435
2436                 // We can't change UTXO capacity on the fly, so we'll disable
2437                 // the existing channel and add another one with the capacity we need.
2438                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2439                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2440                         short_channel_id: 3,
2441                         timestamp: 4,
2442                         flags: 2,
2443                         cltv_expiry_delta: 0,
2444                         htlc_minimum_msat: 0,
2445                         htlc_maximum_msat: OptionalField::Absent,
2446                         fee_base_msat: 0,
2447                         fee_proportional_millionths: 0,
2448                         excess_data: Vec::new()
2449                 });
2450
2451                 let good_script = Builder::new().push_opcode(opcodes::all::OP_PUSHNUM_2)
2452                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[0]).serialize())
2453                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[2]).serialize())
2454                 .push_opcode(opcodes::all::OP_PUSHNUM_2)
2455                 .push_opcode(opcodes::all::OP_CHECKMULTISIG).into_script().to_v0_p2wsh();
2456
2457                 *chain_monitor.utxo_ret.lock().unwrap() = Ok(TxOut { value: 15, script_pubkey: good_script.clone() });
2458                 net_graph_msg_handler.add_chain_access(Some(chain_monitor));
2459
2460                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 333);
2461                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2462                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2463                         short_channel_id: 333,
2464                         timestamp: 1,
2465                         flags: 0,
2466                         cltv_expiry_delta: (3 << 8) | 1,
2467                         htlc_minimum_msat: 0,
2468                         htlc_maximum_msat: OptionalField::Absent,
2469                         fee_base_msat: 0,
2470                         fee_proportional_millionths: 0,
2471                         excess_data: Vec::new()
2472                 });
2473                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2474                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2475                         short_channel_id: 333,
2476                         timestamp: 1,
2477                         flags: 1,
2478                         cltv_expiry_delta: (3 << 8) | 2,
2479                         htlc_minimum_msat: 0,
2480                         htlc_maximum_msat: OptionalField::Absent,
2481                         fee_base_msat: 100,
2482                         fee_proportional_millionths: 0,
2483                         excess_data: Vec::new()
2484                 });
2485
2486                 {
2487                         // Attempt to route more than available results in a failure.
2488                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2489                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 15_001, 42, Arc::clone(&logger)) {
2490                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2491                         } else { panic!(); }
2492                 }
2493
2494                 {
2495                         // Now, attempt to route an exact amount we have should be fine.
2496                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2497                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 15_000, 42, Arc::clone(&logger)).unwrap();
2498                         assert_eq!(route.paths.len(), 1);
2499                         let path = route.paths.last().unwrap();
2500                         assert_eq!(path.len(), 2);
2501                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2502                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
2503                 }
2504
2505                 // Now let's see if routing chooses htlc_maximum_msat over UTXO capacity.
2506                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2507                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2508                         short_channel_id: 333,
2509                         timestamp: 6,
2510                         flags: 0,
2511                         cltv_expiry_delta: 0,
2512                         htlc_minimum_msat: 0,
2513                         htlc_maximum_msat: OptionalField::Present(10_000),
2514                         fee_base_msat: 0,
2515                         fee_proportional_millionths: 0,
2516                         excess_data: Vec::new()
2517                 });
2518
2519                 {
2520                         // Attempt to route more than available results in a failure.
2521                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2522                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 10_001, 42, Arc::clone(&logger)) {
2523                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2524                         } else { panic!(); }
2525                 }
2526
2527                 {
2528                         // Now, attempt to route an exact amount we have should be fine.
2529                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2530                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 10_000, 42, Arc::clone(&logger)).unwrap();
2531                         assert_eq!(route.paths.len(), 1);
2532                         let path = route.paths.last().unwrap();
2533                         assert_eq!(path.len(), 2);
2534                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2535                         assert_eq!(path.last().unwrap().fee_msat, 10_000);
2536                 }
2537         }
2538
2539         #[test]
2540         fn available_liquidity_last_hop_test() {
2541                 // Check that available liquidity properly limits the path even when only
2542                 // one of the latter hops is limited.
2543                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2544                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2545
2546                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
2547                 // {12, 13, 11} have the capacities of 100, {6} has a capacity of 50.
2548                 // Total capacity: 50 sats.
2549
2550                 // Disable other potential paths.
2551                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2552                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2553                         short_channel_id: 2,
2554                         timestamp: 2,
2555                         flags: 2,
2556                         cltv_expiry_delta: 0,
2557                         htlc_minimum_msat: 0,
2558                         htlc_maximum_msat: OptionalField::Present(100_000),
2559                         fee_base_msat: 0,
2560                         fee_proportional_millionths: 0,
2561                         excess_data: Vec::new()
2562                 });
2563                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2564                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2565                         short_channel_id: 7,
2566                         timestamp: 2,
2567                         flags: 2,
2568                         cltv_expiry_delta: 0,
2569                         htlc_minimum_msat: 0,
2570                         htlc_maximum_msat: OptionalField::Present(100_000),
2571                         fee_base_msat: 0,
2572                         fee_proportional_millionths: 0,
2573                         excess_data: Vec::new()
2574                 });
2575
2576                 // Limit capacities
2577
2578                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2579                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2580                         short_channel_id: 12,
2581                         timestamp: 2,
2582                         flags: 0,
2583                         cltv_expiry_delta: 0,
2584                         htlc_minimum_msat: 0,
2585                         htlc_maximum_msat: OptionalField::Present(100_000),
2586                         fee_base_msat: 0,
2587                         fee_proportional_millionths: 0,
2588                         excess_data: Vec::new()
2589                 });
2590                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2591                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2592                         short_channel_id: 13,
2593                         timestamp: 2,
2594                         flags: 0,
2595                         cltv_expiry_delta: 0,
2596                         htlc_minimum_msat: 0,
2597                         htlc_maximum_msat: OptionalField::Present(100_000),
2598                         fee_base_msat: 0,
2599                         fee_proportional_millionths: 0,
2600                         excess_data: Vec::new()
2601                 });
2602
2603                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2604                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2605                         short_channel_id: 6,
2606                         timestamp: 2,
2607                         flags: 0,
2608                         cltv_expiry_delta: 0,
2609                         htlc_minimum_msat: 0,
2610                         htlc_maximum_msat: OptionalField::Present(50_000),
2611                         fee_base_msat: 0,
2612                         fee_proportional_millionths: 0,
2613                         excess_data: Vec::new()
2614                 });
2615                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
2616                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2617                         short_channel_id: 11,
2618                         timestamp: 2,
2619                         flags: 0,
2620                         cltv_expiry_delta: 0,
2621                         htlc_minimum_msat: 0,
2622                         htlc_maximum_msat: OptionalField::Present(100_000),
2623                         fee_base_msat: 0,
2624                         fee_proportional_millionths: 0,
2625                         excess_data: Vec::new()
2626                 });
2627                 {
2628                         // Attempt to route more than available results in a failure.
2629                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2630                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)) {
2631                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2632                         } else { panic!(); }
2633                 }
2634
2635                 {
2636                         // Now, attempt to route 49 sats (just a bit below the capacity).
2637                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2638                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 49_000, 42, Arc::clone(&logger)).unwrap();
2639                         assert_eq!(route.paths.len(), 1);
2640                         let mut total_amount_paid_msat = 0;
2641                         for path in &route.paths {
2642                                 assert_eq!(path.len(), 4);
2643                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
2644                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2645                         }
2646                         assert_eq!(total_amount_paid_msat, 49_000);
2647                 }
2648
2649                 {
2650                         // Attempt to route an exact amount is also fine
2651                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2652                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
2653                         assert_eq!(route.paths.len(), 1);
2654                         let mut total_amount_paid_msat = 0;
2655                         for path in &route.paths {
2656                                 assert_eq!(path.len(), 4);
2657                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
2658                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2659                         }
2660                         assert_eq!(total_amount_paid_msat, 50_000);
2661                 }
2662         }
2663
2664         #[test]
2665         fn ignore_fee_first_hop_test() {
2666                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2667                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2668
2669                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
2670                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2671                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2672                         short_channel_id: 1,
2673                         timestamp: 2,
2674                         flags: 0,
2675                         cltv_expiry_delta: 0,
2676                         htlc_minimum_msat: 0,
2677                         htlc_maximum_msat: OptionalField::Present(100_000),
2678                         fee_base_msat: 1_000_000,
2679                         fee_proportional_millionths: 0,
2680                         excess_data: Vec::new()
2681                 });
2682                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2683                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2684                         short_channel_id: 3,
2685                         timestamp: 2,
2686                         flags: 0,
2687                         cltv_expiry_delta: 0,
2688                         htlc_minimum_msat: 0,
2689                         htlc_maximum_msat: OptionalField::Present(50_000),
2690                         fee_base_msat: 0,
2691                         fee_proportional_millionths: 0,
2692                         excess_data: Vec::new()
2693                 });
2694
2695                 {
2696                         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();
2697                         assert_eq!(route.paths.len(), 1);
2698                         let mut total_amount_paid_msat = 0;
2699                         for path in &route.paths {
2700                                 assert_eq!(path.len(), 2);
2701                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2702                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2703                         }
2704                         assert_eq!(total_amount_paid_msat, 50_000);
2705                 }
2706         }
2707
2708         #[test]
2709         fn simple_mpp_route_test() {
2710                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2711                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2712
2713                 // We need a route consisting of 3 paths:
2714                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
2715                 // To achieve this, the amount being transferred should be around
2716                 // the total capacity of these 3 paths.
2717
2718                 // First, we set limits on these (previously unlimited) channels.
2719                 // Their aggregate capacity will be 50 + 60 + 180 = 290 sats.
2720
2721                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
2722                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2723                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2724                         short_channel_id: 1,
2725                         timestamp: 2,
2726                         flags: 0,
2727                         cltv_expiry_delta: 0,
2728                         htlc_minimum_msat: 0,
2729                         htlc_maximum_msat: OptionalField::Present(100_000),
2730                         fee_base_msat: 0,
2731                         fee_proportional_millionths: 0,
2732                         excess_data: Vec::new()
2733                 });
2734                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2735                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2736                         short_channel_id: 3,
2737                         timestamp: 2,
2738                         flags: 0,
2739                         cltv_expiry_delta: 0,
2740                         htlc_minimum_msat: 0,
2741                         htlc_maximum_msat: OptionalField::Present(50_000),
2742                         fee_base_msat: 0,
2743                         fee_proportional_millionths: 0,
2744                         excess_data: Vec::new()
2745                 });
2746
2747                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats
2748                 // (total limit 60).
2749                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2750                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2751                         short_channel_id: 12,
2752                         timestamp: 2,
2753                         flags: 0,
2754                         cltv_expiry_delta: 0,
2755                         htlc_minimum_msat: 0,
2756                         htlc_maximum_msat: OptionalField::Present(60_000),
2757                         fee_base_msat: 0,
2758                         fee_proportional_millionths: 0,
2759                         excess_data: Vec::new()
2760                 });
2761                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2762                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2763                         short_channel_id: 13,
2764                         timestamp: 2,
2765                         flags: 0,
2766                         cltv_expiry_delta: 0,
2767                         htlc_minimum_msat: 0,
2768                         htlc_maximum_msat: OptionalField::Present(60_000),
2769                         fee_base_msat: 0,
2770                         fee_proportional_millionths: 0,
2771                         excess_data: Vec::new()
2772                 });
2773
2774                 // Path via node1 is channels {2, 4}. Limit them to 200 and 180 sats
2775                 // (total capacity 180 sats).
2776                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2777                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2778                         short_channel_id: 2,
2779                         timestamp: 2,
2780                         flags: 0,
2781                         cltv_expiry_delta: 0,
2782                         htlc_minimum_msat: 0,
2783                         htlc_maximum_msat: OptionalField::Present(200_000),
2784                         fee_base_msat: 0,
2785                         fee_proportional_millionths: 0,
2786                         excess_data: Vec::new()
2787                 });
2788                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2789                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2790                         short_channel_id: 4,
2791                         timestamp: 2,
2792                         flags: 0,
2793                         cltv_expiry_delta: 0,
2794                         htlc_minimum_msat: 0,
2795                         htlc_maximum_msat: OptionalField::Present(180_000),
2796                         fee_base_msat: 0,
2797                         fee_proportional_millionths: 0,
2798                         excess_data: Vec::new()
2799                 });
2800
2801                 {
2802                         // Attempt to route more than available results in a failure.
2803                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(),
2804                                         &nodes[2], Some(InvoiceFeatures::known()), None, &Vec::new(), 300_000, 42, Arc::clone(&logger)) {
2805                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2806                         } else { panic!(); }
2807                 }
2808
2809                 {
2810                         // Now, attempt to route 250 sats (just a bit below the capacity).
2811                         // Our algorithm should provide us with these 3 paths.
2812                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2813                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000, 42, Arc::clone(&logger)).unwrap();
2814                         assert_eq!(route.paths.len(), 3);
2815                         let mut total_amount_paid_msat = 0;
2816                         for path in &route.paths {
2817                                 assert_eq!(path.len(), 2);
2818                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2819                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2820                         }
2821                         assert_eq!(total_amount_paid_msat, 250_000);
2822                 }
2823
2824                 {
2825                         // Attempt to route an exact amount is also fine
2826                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2827                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 290_000, 42, Arc::clone(&logger)).unwrap();
2828                         assert_eq!(route.paths.len(), 3);
2829                         let mut total_amount_paid_msat = 0;
2830                         for path in &route.paths {
2831                                 assert_eq!(path.len(), 2);
2832                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2833                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2834                         }
2835                         assert_eq!(total_amount_paid_msat, 290_000);
2836                 }
2837         }
2838
2839         #[test]
2840         fn long_mpp_route_test() {
2841                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2842                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2843
2844                 // We need a route consisting of 3 paths:
2845                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
2846                 // Note that these paths overlap (channels 5, 12, 13).
2847                 // We will route 300 sats.
2848                 // Each path will have 100 sats capacity, those channels which
2849                 // are used twice will have 200 sats capacity.
2850
2851                 // Disable other potential paths.
2852                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2853                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2854                         short_channel_id: 2,
2855                         timestamp: 2,
2856                         flags: 2,
2857                         cltv_expiry_delta: 0,
2858                         htlc_minimum_msat: 0,
2859                         htlc_maximum_msat: OptionalField::Present(100_000),
2860                         fee_base_msat: 0,
2861                         fee_proportional_millionths: 0,
2862                         excess_data: Vec::new()
2863                 });
2864                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2865                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2866                         short_channel_id: 7,
2867                         timestamp: 2,
2868                         flags: 2,
2869                         cltv_expiry_delta: 0,
2870                         htlc_minimum_msat: 0,
2871                         htlc_maximum_msat: OptionalField::Present(100_000),
2872                         fee_base_msat: 0,
2873                         fee_proportional_millionths: 0,
2874                         excess_data: Vec::new()
2875                 });
2876
2877                 // Path via {node0, node2} is channels {1, 3, 5}.
2878                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2879                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2880                         short_channel_id: 1,
2881                         timestamp: 2,
2882                         flags: 0,
2883                         cltv_expiry_delta: 0,
2884                         htlc_minimum_msat: 0,
2885                         htlc_maximum_msat: OptionalField::Present(100_000),
2886                         fee_base_msat: 0,
2887                         fee_proportional_millionths: 0,
2888                         excess_data: Vec::new()
2889                 });
2890                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2891                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2892                         short_channel_id: 3,
2893                         timestamp: 2,
2894                         flags: 0,
2895                         cltv_expiry_delta: 0,
2896                         htlc_minimum_msat: 0,
2897                         htlc_maximum_msat: OptionalField::Present(100_000),
2898                         fee_base_msat: 0,
2899                         fee_proportional_millionths: 0,
2900                         excess_data: Vec::new()
2901                 });
2902
2903                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
2904                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
2905                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2906                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2907                         short_channel_id: 5,
2908                         timestamp: 2,
2909                         flags: 0,
2910                         cltv_expiry_delta: 0,
2911                         htlc_minimum_msat: 0,
2912                         htlc_maximum_msat: OptionalField::Present(200_000),
2913                         fee_base_msat: 0,
2914                         fee_proportional_millionths: 0,
2915                         excess_data: Vec::new()
2916                 });
2917
2918                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
2919                 // Add 100 sats to the capacities of {12, 13}, because these channels
2920                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
2921                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2922                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2923                         short_channel_id: 12,
2924                         timestamp: 2,
2925                         flags: 0,
2926                         cltv_expiry_delta: 0,
2927                         htlc_minimum_msat: 0,
2928                         htlc_maximum_msat: OptionalField::Present(200_000),
2929                         fee_base_msat: 0,
2930                         fee_proportional_millionths: 0,
2931                         excess_data: Vec::new()
2932                 });
2933                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2934                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2935                         short_channel_id: 13,
2936                         timestamp: 2,
2937                         flags: 0,
2938                         cltv_expiry_delta: 0,
2939                         htlc_minimum_msat: 0,
2940                         htlc_maximum_msat: OptionalField::Present(200_000),
2941                         fee_base_msat: 0,
2942                         fee_proportional_millionths: 0,
2943                         excess_data: Vec::new()
2944                 });
2945
2946                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2947                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2948                         short_channel_id: 6,
2949                         timestamp: 2,
2950                         flags: 0,
2951                         cltv_expiry_delta: 0,
2952                         htlc_minimum_msat: 0,
2953                         htlc_maximum_msat: OptionalField::Present(100_000),
2954                         fee_base_msat: 0,
2955                         fee_proportional_millionths: 0,
2956                         excess_data: Vec::new()
2957                 });
2958                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
2959                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2960                         short_channel_id: 11,
2961                         timestamp: 2,
2962                         flags: 0,
2963                         cltv_expiry_delta: 0,
2964                         htlc_minimum_msat: 0,
2965                         htlc_maximum_msat: OptionalField::Present(100_000),
2966                         fee_base_msat: 0,
2967                         fee_proportional_millionths: 0,
2968                         excess_data: Vec::new()
2969                 });
2970
2971                 // Path via {node7, node2} is channels {12, 13, 5}.
2972                 // We already limited them to 200 sats (they are used twice for 100 sats).
2973                 // Nothing to do here.
2974
2975                 {
2976                         // Attempt to route more than available results in a failure.
2977                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2978                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 350_000, 42, Arc::clone(&logger)) {
2979                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2980                         } else { panic!(); }
2981                 }
2982
2983                 {
2984                         // Now, attempt to route 300 sats (exact amount we can route).
2985                         // Our algorithm should provide us with these 3 paths, 100 sats each.
2986                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2987                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 300_000, 42, Arc::clone(&logger)).unwrap();
2988                         assert_eq!(route.paths.len(), 3);
2989
2990                         let mut total_amount_paid_msat = 0;
2991                         for path in &route.paths {
2992                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
2993                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2994                         }
2995                         assert_eq!(total_amount_paid_msat, 300_000);
2996                 }
2997
2998         }
2999
3000         #[test]
3001         fn mpp_cheaper_route_test() {
3002                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3003                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3004
3005                 // This test checks that if we have two cheaper paths and one more expensive path,
3006                 // so that liquidity-wise any 2 of 3 combination is sufficient,
3007                 // two cheaper paths will be taken.
3008                 // These paths have equal available liquidity.
3009
3010                 // We need a combination of 3 paths:
3011                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
3012                 // Note that these paths overlap (channels 5, 12, 13).
3013                 // Each path will have 100 sats capacity, those channels which
3014                 // are used twice will have 200 sats capacity.
3015
3016                 // Disable other potential paths.
3017                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3018                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3019                         short_channel_id: 2,
3020                         timestamp: 2,
3021                         flags: 2,
3022                         cltv_expiry_delta: 0,
3023                         htlc_minimum_msat: 0,
3024                         htlc_maximum_msat: OptionalField::Present(100_000),
3025                         fee_base_msat: 0,
3026                         fee_proportional_millionths: 0,
3027                         excess_data: Vec::new()
3028                 });
3029                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3030                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3031                         short_channel_id: 7,
3032                         timestamp: 2,
3033                         flags: 2,
3034                         cltv_expiry_delta: 0,
3035                         htlc_minimum_msat: 0,
3036                         htlc_maximum_msat: OptionalField::Present(100_000),
3037                         fee_base_msat: 0,
3038                         fee_proportional_millionths: 0,
3039                         excess_data: Vec::new()
3040                 });
3041
3042                 // Path via {node0, node2} is channels {1, 3, 5}.
3043                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3044                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3045                         short_channel_id: 1,
3046                         timestamp: 2,
3047                         flags: 0,
3048                         cltv_expiry_delta: 0,
3049                         htlc_minimum_msat: 0,
3050                         htlc_maximum_msat: OptionalField::Present(100_000),
3051                         fee_base_msat: 0,
3052                         fee_proportional_millionths: 0,
3053                         excess_data: Vec::new()
3054                 });
3055                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3056                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3057                         short_channel_id: 3,
3058                         timestamp: 2,
3059                         flags: 0,
3060                         cltv_expiry_delta: 0,
3061                         htlc_minimum_msat: 0,
3062                         htlc_maximum_msat: OptionalField::Present(100_000),
3063                         fee_base_msat: 0,
3064                         fee_proportional_millionths: 0,
3065                         excess_data: Vec::new()
3066                 });
3067
3068                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3069                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3070                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3071                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3072                         short_channel_id: 5,
3073                         timestamp: 2,
3074                         flags: 0,
3075                         cltv_expiry_delta: 0,
3076                         htlc_minimum_msat: 0,
3077                         htlc_maximum_msat: OptionalField::Present(200_000),
3078                         fee_base_msat: 0,
3079                         fee_proportional_millionths: 0,
3080                         excess_data: Vec::new()
3081                 });
3082
3083                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3084                 // Add 100 sats to the capacities of {12, 13}, because these channels
3085                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3086                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3087                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3088                         short_channel_id: 12,
3089                         timestamp: 2,
3090                         flags: 0,
3091                         cltv_expiry_delta: 0,
3092                         htlc_minimum_msat: 0,
3093                         htlc_maximum_msat: OptionalField::Present(200_000),
3094                         fee_base_msat: 0,
3095                         fee_proportional_millionths: 0,
3096                         excess_data: Vec::new()
3097                 });
3098                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3099                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3100                         short_channel_id: 13,
3101                         timestamp: 2,
3102                         flags: 0,
3103                         cltv_expiry_delta: 0,
3104                         htlc_minimum_msat: 0,
3105                         htlc_maximum_msat: OptionalField::Present(200_000),
3106                         fee_base_msat: 0,
3107                         fee_proportional_millionths: 0,
3108                         excess_data: Vec::new()
3109                 });
3110
3111                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3112                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3113                         short_channel_id: 6,
3114                         timestamp: 2,
3115                         flags: 0,
3116                         cltv_expiry_delta: 0,
3117                         htlc_minimum_msat: 0,
3118                         htlc_maximum_msat: OptionalField::Present(100_000),
3119                         fee_base_msat: 1_000,
3120                         fee_proportional_millionths: 0,
3121                         excess_data: Vec::new()
3122                 });
3123                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3124                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3125                         short_channel_id: 11,
3126                         timestamp: 2,
3127                         flags: 0,
3128                         cltv_expiry_delta: 0,
3129                         htlc_minimum_msat: 0,
3130                         htlc_maximum_msat: OptionalField::Present(100_000),
3131                         fee_base_msat: 0,
3132                         fee_proportional_millionths: 0,
3133                         excess_data: Vec::new()
3134                 });
3135
3136                 // Path via {node7, node2} is channels {12, 13, 5}.
3137                 // We already limited them to 200 sats (they are used twice for 100 sats).
3138                 // Nothing to do here.
3139
3140                 {
3141                         // Now, attempt to route 180 sats.
3142                         // Our algorithm should provide us with these 2 paths.
3143                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3144                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 180_000, 42, Arc::clone(&logger)).unwrap();
3145                         assert_eq!(route.paths.len(), 2);
3146
3147                         let mut total_value_transferred_msat = 0;
3148                         let mut total_paid_msat = 0;
3149                         for path in &route.paths {
3150                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3151                                 total_value_transferred_msat += path.last().unwrap().fee_msat;
3152                                 for hop in path {
3153                                         total_paid_msat += hop.fee_msat;
3154                                 }
3155                         }
3156                         // If we paid fee, this would be higher.
3157                         assert_eq!(total_value_transferred_msat, 180_000);
3158                         let total_fees_paid = total_paid_msat - total_value_transferred_msat;
3159                         assert_eq!(total_fees_paid, 0);
3160                 }
3161         }
3162
3163         #[test]
3164         fn fees_on_mpp_route_test() {
3165                 // This test makes sure that MPP algorithm properly takes into account
3166                 // fees charged on the channels, by making the fees impactful:
3167                 // if the fee is not properly accounted for, the behavior is different.
3168                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3169                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3170
3171                 // We need a route consisting of 2 paths:
3172                 // From our node to node3 via {node0, node2} and {node7, node2, node4}.
3173                 // We will route 200 sats, Each path will have 100 sats capacity.
3174
3175                 // This test is not particularly stable: e.g.,
3176                 // there's a way to route via {node0, node2, node4}.
3177                 // It works while pathfinding is deterministic, but can be broken otherwise.
3178                 // It's fine to ignore this concern for now.
3179
3180                 // Disable other potential paths.
3181                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3182                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3183                         short_channel_id: 2,
3184                         timestamp: 2,
3185                         flags: 2,
3186                         cltv_expiry_delta: 0,
3187                         htlc_minimum_msat: 0,
3188                         htlc_maximum_msat: OptionalField::Present(100_000),
3189                         fee_base_msat: 0,
3190                         fee_proportional_millionths: 0,
3191                         excess_data: Vec::new()
3192                 });
3193
3194                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3195                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3196                         short_channel_id: 7,
3197                         timestamp: 2,
3198                         flags: 2,
3199                         cltv_expiry_delta: 0,
3200                         htlc_minimum_msat: 0,
3201                         htlc_maximum_msat: OptionalField::Present(100_000),
3202                         fee_base_msat: 0,
3203                         fee_proportional_millionths: 0,
3204                         excess_data: Vec::new()
3205                 });
3206
3207                 // Path via {node0, node2} is channels {1, 3, 5}.
3208                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3209                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3210                         short_channel_id: 1,
3211                         timestamp: 2,
3212                         flags: 0,
3213                         cltv_expiry_delta: 0,
3214                         htlc_minimum_msat: 0,
3215                         htlc_maximum_msat: OptionalField::Present(100_000),
3216                         fee_base_msat: 0,
3217                         fee_proportional_millionths: 0,
3218                         excess_data: Vec::new()
3219                 });
3220                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3221                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3222                         short_channel_id: 3,
3223                         timestamp: 2,
3224                         flags: 0,
3225                         cltv_expiry_delta: 0,
3226                         htlc_minimum_msat: 0,
3227                         htlc_maximum_msat: OptionalField::Present(100_000),
3228                         fee_base_msat: 0,
3229                         fee_proportional_millionths: 0,
3230                         excess_data: Vec::new()
3231                 });
3232
3233                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3234                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3235                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3236                         short_channel_id: 5,
3237                         timestamp: 2,
3238                         flags: 0,
3239                         cltv_expiry_delta: 0,
3240                         htlc_minimum_msat: 0,
3241                         htlc_maximum_msat: OptionalField::Present(100_000),
3242                         fee_base_msat: 0,
3243                         fee_proportional_millionths: 0,
3244                         excess_data: Vec::new()
3245                 });
3246
3247                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3248                 // All channels should be 100 sats capacity. But for the fee experiment,
3249                 // we'll add absolute fee of 150 sats paid for the use channel 6 (paid to node2 on channel 13).
3250                 // Since channel 12 allows to deliver only 250 sats to channel 13, channel 13 can transfer only
3251                 // 100 sats (and pay 150 sats in fees for the use of channel 6),
3252                 // so no matter how large are other channels,
3253                 // the whole path will be limited by 100 sats with just these 2 conditions:
3254                 // - channel 12 capacity is 250 sats
3255                 // - fee for channel 6 is 150 sats
3256                 // Let's test this by enforcing these 2 conditions and removing other limits.
3257                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3258                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3259                         short_channel_id: 12,
3260                         timestamp: 2,
3261                         flags: 0,
3262                         cltv_expiry_delta: 0,
3263                         htlc_minimum_msat: 0,
3264                         htlc_maximum_msat: OptionalField::Present(250_000),
3265                         fee_base_msat: 0,
3266                         fee_proportional_millionths: 0,
3267                         excess_data: Vec::new()
3268                 });
3269                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3270                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3271                         short_channel_id: 13,
3272                         timestamp: 2,
3273                         flags: 0,
3274                         cltv_expiry_delta: 0,
3275                         htlc_minimum_msat: 0,
3276                         htlc_maximum_msat: OptionalField::Absent,
3277                         fee_base_msat: 0,
3278                         fee_proportional_millionths: 0,
3279                         excess_data: Vec::new()
3280                 });
3281
3282                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3283                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3284                         short_channel_id: 6,
3285                         timestamp: 2,
3286                         flags: 0,
3287                         cltv_expiry_delta: 0,
3288                         htlc_minimum_msat: 0,
3289                         htlc_maximum_msat: OptionalField::Absent,
3290                         fee_base_msat: 150_000,
3291                         fee_proportional_millionths: 0,
3292                         excess_data: Vec::new()
3293                 });
3294                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3295                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3296                         short_channel_id: 11,
3297                         timestamp: 2,
3298                         flags: 0,
3299                         cltv_expiry_delta: 0,
3300                         htlc_minimum_msat: 0,
3301                         htlc_maximum_msat: OptionalField::Absent,
3302                         fee_base_msat: 0,
3303                         fee_proportional_millionths: 0,
3304                         excess_data: Vec::new()
3305                 });
3306
3307                 {
3308                         // Attempt to route more than available results in a failure.
3309                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3310                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 210_000, 42, Arc::clone(&logger)) {
3311                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3312                         } else { panic!(); }
3313                 }
3314
3315                 {
3316                         // Now, attempt to route 200 sats (exact amount we can route).
3317                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3318                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 200_000, 42, Arc::clone(&logger)).unwrap();
3319                         assert_eq!(route.paths.len(), 2);
3320
3321                         let mut total_amount_paid_msat = 0;
3322                         for path in &route.paths {
3323                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3324                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3325                         }
3326                         assert_eq!(total_amount_paid_msat, 200_000);
3327                 }
3328
3329         }
3330
3331         #[test]
3332         fn drop_lowest_channel_mpp_route_test() {
3333                 // This test checks that low-capacity channel is dropped when after
3334                 // path finding we realize that we found more capacity than we need.
3335                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3336                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3337
3338                 // We need a route consisting of 3 paths:
3339                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
3340
3341                 // The first and the second paths should be sufficient, but the third should be
3342                 // cheaper, so that we select it but drop later.
3343
3344                 // First, we set limits on these (previously unlimited) channels.
3345                 // Their aggregate capacity will be 50 + 60 + 20 = 130 sats.
3346
3347                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50);
3348                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3349                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3350                         short_channel_id: 1,
3351                         timestamp: 2,
3352                         flags: 0,
3353                         cltv_expiry_delta: 0,
3354                         htlc_minimum_msat: 0,
3355                         htlc_maximum_msat: OptionalField::Present(100_000),
3356                         fee_base_msat: 0,
3357                         fee_proportional_millionths: 0,
3358                         excess_data: Vec::new()
3359                 });
3360                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3361                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3362                         short_channel_id: 3,
3363                         timestamp: 2,
3364                         flags: 0,
3365                         cltv_expiry_delta: 0,
3366                         htlc_minimum_msat: 0,
3367                         htlc_maximum_msat: OptionalField::Present(50_000),
3368                         fee_base_msat: 100,
3369                         fee_proportional_millionths: 0,
3370                         excess_data: Vec::new()
3371                 });
3372
3373                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats (total limit 60);
3374                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3375                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3376                         short_channel_id: 12,
3377                         timestamp: 2,
3378                         flags: 0,
3379                         cltv_expiry_delta: 0,
3380                         htlc_minimum_msat: 0,
3381                         htlc_maximum_msat: OptionalField::Present(60_000),
3382                         fee_base_msat: 100,
3383                         fee_proportional_millionths: 0,
3384                         excess_data: Vec::new()
3385                 });
3386                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3387                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3388                         short_channel_id: 13,
3389                         timestamp: 2,
3390                         flags: 0,
3391                         cltv_expiry_delta: 0,
3392                         htlc_minimum_msat: 0,
3393                         htlc_maximum_msat: OptionalField::Present(60_000),
3394                         fee_base_msat: 0,
3395                         fee_proportional_millionths: 0,
3396                         excess_data: Vec::new()
3397                 });
3398
3399                 // Path via node1 is channels {2, 4}. Limit them to 20 and 20 sats (total capacity 20 sats).
3400                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3401                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3402                         short_channel_id: 2,
3403                         timestamp: 2,
3404                         flags: 0,
3405                         cltv_expiry_delta: 0,
3406                         htlc_minimum_msat: 0,
3407                         htlc_maximum_msat: OptionalField::Present(20_000),
3408                         fee_base_msat: 0,
3409                         fee_proportional_millionths: 0,
3410                         excess_data: Vec::new()
3411                 });
3412                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3413                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3414                         short_channel_id: 4,
3415                         timestamp: 2,
3416                         flags: 0,
3417                         cltv_expiry_delta: 0,
3418                         htlc_minimum_msat: 0,
3419                         htlc_maximum_msat: OptionalField::Present(20_000),
3420                         fee_base_msat: 0,
3421                         fee_proportional_millionths: 0,
3422                         excess_data: Vec::new()
3423                 });
3424
3425                 {
3426                         // Attempt to route more than available results in a failure.
3427                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3428                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 150_000, 42, Arc::clone(&logger)) {
3429                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3430                         } else { panic!(); }
3431                 }
3432
3433                 {
3434                         // Now, attempt to route 125 sats (just a bit below the capacity of 3 channels).
3435                         // Our algorithm should provide us with these 3 paths.
3436                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3437                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 125_000, 42, Arc::clone(&logger)).unwrap();
3438                         assert_eq!(route.paths.len(), 3);
3439                         let mut total_amount_paid_msat = 0;
3440                         for path in &route.paths {
3441                                 assert_eq!(path.len(), 2);
3442                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3443                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3444                         }
3445                         assert_eq!(total_amount_paid_msat, 125_000);
3446                 }
3447
3448                 {
3449                         // Attempt to route without the last small cheap channel
3450                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3451                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
3452                         assert_eq!(route.paths.len(), 2);
3453                         let mut total_amount_paid_msat = 0;
3454                         for path in &route.paths {
3455                                 assert_eq!(path.len(), 2);
3456                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3457                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3458                         }
3459                         assert_eq!(total_amount_paid_msat, 90_000);
3460                 }
3461         }
3462
3463         #[test]
3464         fn min_criteria_consistency() {
3465                 // Test that we don't use an inconsistent metric between updating and walking nodes during
3466                 // our Dijkstra's pass. In the initial version of MPP, the "best source" for a given node
3467                 // was updated with a different critera from the heap sorting, resulting in loops in
3468                 // calculated paths. We test for that specific case here.
3469
3470                 // We construct a network that looks like this:
3471                 //
3472                 //            node2 -1(3)2- node3
3473                 //              2          2
3474                 //               (2)     (4)
3475                 //                  1   1
3476                 //    node1 -1(5)2- node4 -1(1)2- node6
3477                 //    2
3478                 //   (6)
3479                 //        1
3480                 // our_node
3481                 //
3482                 // We create a loop on the side of our real path - our destination is node 6, with a
3483                 // previous hop of node 4. From 4, the cheapest previous path is channel 2 from node 2,
3484                 // followed by node 3 over channel 3. Thereafter, the cheapest next-hop is back to node 4
3485                 // (this time over channel 4). Channel 4 has 0 htlc_minimum_msat whereas channel 1 (the
3486                 // other channel with a previous-hop of node 4) has a high (but irrelevant to the overall
3487                 // payment) htlc_minimum_msat. In the original algorithm, this resulted in node4's
3488                 // "previous hop" being set to node 3, creating a loop in the path.
3489                 let secp_ctx = Secp256k1::new();
3490                 let logger = Arc::new(test_utils::TestLogger::new());
3491                 let net_graph_msg_handler = NetGraphMsgHandler::new(genesis_block(Network::Testnet).header.block_hash(), None, Arc::clone(&logger));
3492                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3493
3494                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
3495                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3496                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3497                         short_channel_id: 6,
3498                         timestamp: 1,
3499                         flags: 0,
3500                         cltv_expiry_delta: (6 << 8) | 0,
3501                         htlc_minimum_msat: 0,
3502                         htlc_maximum_msat: OptionalField::Absent,
3503                         fee_base_msat: 0,
3504                         fee_proportional_millionths: 0,
3505                         excess_data: Vec::new()
3506                 });
3507                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
3508
3509                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3510                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3511                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3512                         short_channel_id: 5,
3513                         timestamp: 1,
3514                         flags: 0,
3515                         cltv_expiry_delta: (5 << 8) | 0,
3516                         htlc_minimum_msat: 0,
3517                         htlc_maximum_msat: OptionalField::Absent,
3518                         fee_base_msat: 100,
3519                         fee_proportional_millionths: 0,
3520                         excess_data: Vec::new()
3521                 });
3522                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
3523
3524                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
3525                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3526                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3527                         short_channel_id: 4,
3528                         timestamp: 1,
3529                         flags: 0,
3530                         cltv_expiry_delta: (4 << 8) | 0,
3531                         htlc_minimum_msat: 0,
3532                         htlc_maximum_msat: OptionalField::Absent,
3533                         fee_base_msat: 0,
3534                         fee_proportional_millionths: 0,
3535                         excess_data: Vec::new()
3536                 });
3537                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
3538
3539                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
3540                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
3541                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3542                         short_channel_id: 3,
3543                         timestamp: 1,
3544                         flags: 0,
3545                         cltv_expiry_delta: (3 << 8) | 0,
3546                         htlc_minimum_msat: 0,
3547                         htlc_maximum_msat: OptionalField::Absent,
3548                         fee_base_msat: 0,
3549                         fee_proportional_millionths: 0,
3550                         excess_data: Vec::new()
3551                 });
3552                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
3553
3554                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
3555                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3556                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3557                         short_channel_id: 2,
3558                         timestamp: 1,
3559                         flags: 0,
3560                         cltv_expiry_delta: (2 << 8) | 0,
3561                         htlc_minimum_msat: 0,
3562                         htlc_maximum_msat: OptionalField::Absent,
3563                         fee_base_msat: 0,
3564                         fee_proportional_millionths: 0,
3565                         excess_data: Vec::new()
3566                 });
3567
3568                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[6], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
3569                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3570                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3571                         short_channel_id: 1,
3572                         timestamp: 1,
3573                         flags: 0,
3574                         cltv_expiry_delta: (1 << 8) | 0,
3575                         htlc_minimum_msat: 100,
3576                         htlc_maximum_msat: OptionalField::Absent,
3577                         fee_base_msat: 0,
3578                         fee_proportional_millionths: 0,
3579                         excess_data: Vec::new()
3580                 });
3581                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[6], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
3582
3583                 {
3584                         // Now ensure the route flows simply over nodes 1 and 4 to 6.
3585                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[6], None, None, &Vec::new(), 10_000, 42, Arc::clone(&logger)).unwrap();
3586                         assert_eq!(route.paths.len(), 1);
3587                         assert_eq!(route.paths[0].len(), 3);
3588
3589                         assert_eq!(route.paths[0][0].pubkey, nodes[1]);
3590                         assert_eq!(route.paths[0][0].short_channel_id, 6);
3591                         assert_eq!(route.paths[0][0].fee_msat, 100);
3592                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (5 << 8) | 0);
3593                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(1));
3594                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(6));
3595
3596                         assert_eq!(route.paths[0][1].pubkey, nodes[4]);
3597                         assert_eq!(route.paths[0][1].short_channel_id, 5);
3598                         assert_eq!(route.paths[0][1].fee_msat, 0);
3599                         assert_eq!(route.paths[0][1].cltv_expiry_delta, (1 << 8) | 0);
3600                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(4));
3601                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(5));
3602
3603                         assert_eq!(route.paths[0][2].pubkey, nodes[6]);
3604                         assert_eq!(route.paths[0][2].short_channel_id, 1);
3605                         assert_eq!(route.paths[0][2].fee_msat, 10_000);
3606                         assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
3607                         assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
3608                         assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(1));
3609                 }
3610         }
3611
3612
3613         #[test]
3614         fn exact_fee_liquidity_limit() {
3615                 // Test that if, while walking the graph, we find a hop that has exactly enough liquidity
3616                 // for us, including later hop fees, we take it. In the first version of our MPP algorithm
3617                 // we calculated fees on a higher value, resulting in us ignoring such paths.
3618                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3619                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3620
3621                 // We modify the graph to set the htlc_maximum of channel 2 to below the value we wish to
3622                 // send.
3623                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3624                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3625                         short_channel_id: 2,
3626                         timestamp: 2,
3627                         flags: 0,
3628                         cltv_expiry_delta: 0,
3629                         htlc_minimum_msat: 0,
3630                         htlc_maximum_msat: OptionalField::Present(85_000),
3631                         fee_base_msat: 0,
3632                         fee_proportional_millionths: 0,
3633                         excess_data: Vec::new()
3634                 });
3635
3636                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3637                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3638                         short_channel_id: 12,
3639                         timestamp: 2,
3640                         flags: 0,
3641                         cltv_expiry_delta: (4 << 8) | 1,
3642                         htlc_minimum_msat: 0,
3643                         htlc_maximum_msat: OptionalField::Present(270_000),
3644                         fee_base_msat: 0,
3645                         fee_proportional_millionths: 1000000,
3646                         excess_data: Vec::new()
3647                 });
3648
3649                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3650                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3651                         short_channel_id: 13,
3652                         timestamp: 2,
3653                         flags: 1 | 2,
3654                         cltv_expiry_delta: (13 << 8) | 2,
3655                         htlc_minimum_msat: 0,
3656                         htlc_maximum_msat: OptionalField::Absent,
3657                         fee_base_msat: 0,
3658                         fee_proportional_millionths: 0,
3659                         excess_data: Vec::new()
3660                 });
3661
3662                 {
3663                         // Now, attempt to route 125 sats (just a bit below the capacity of 3 channels).
3664                         // Our algorithm should provide us with these 3 paths.
3665                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
3666                         assert_eq!(route.paths.len(), 1);
3667                         assert_eq!(route.paths[0].len(), 2);
3668
3669                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
3670                         assert_eq!(route.paths[0][0].short_channel_id, 12);
3671                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
3672                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
3673                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
3674                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
3675
3676                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
3677                         assert_eq!(route.paths[0][1].short_channel_id, 13);
3678                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
3679                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
3680                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
3681                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
3682                 }
3683         }
3684
3685         #[test]
3686         fn htlc_max_reduction_below_min() {
3687                 // Test that if, while walking the graph, we reduce the value being sent to meet an
3688                 // htlc_maximum_msat, we don't end up undershooting a later htlc_minimum_msat. In the
3689                 // initial version of MPP we'd accept such routes but reject them while recalculating fees,
3690                 // resulting in us thinking there is no possible path, even if other paths exist.
3691                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3692                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3693
3694                 // We modify the graph to set the htlc_minimum of channel 2 and 4 as needed - channel 2
3695                 // gets an htlc_minimum_msat of 80_000 and channel 4 an htlc_maximum_msat of 90_000. We
3696                 // then try to send 90_000.
3697                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3698                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3699                         short_channel_id: 2,
3700                         timestamp: 2,
3701                         flags: 0,
3702                         cltv_expiry_delta: 0,
3703                         htlc_minimum_msat: 0,
3704                         htlc_maximum_msat: OptionalField::Present(80_000),
3705                         fee_base_msat: 0,
3706                         fee_proportional_millionths: 0,
3707                         excess_data: Vec::new()
3708                 });
3709                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3710                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3711                         short_channel_id: 4,
3712                         timestamp: 2,
3713                         flags: 0,
3714                         cltv_expiry_delta: (4 << 8) | 1,
3715                         htlc_minimum_msat: 90_000,
3716                         htlc_maximum_msat: OptionalField::Absent,
3717                         fee_base_msat: 0,
3718                         fee_proportional_millionths: 0,
3719                         excess_data: Vec::new()
3720                 });
3721
3722                 {
3723                         // Now, attempt to route 125 sats (just a bit below the capacity of 3 channels).
3724                         // Our algorithm should provide us with these 3 paths.
3725                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], Some(InvoiceFeatures::known()), None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
3726                         assert_eq!(route.paths.len(), 1);
3727                         assert_eq!(route.paths[0].len(), 2);
3728
3729                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
3730                         assert_eq!(route.paths[0][0].short_channel_id, 12);
3731                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
3732                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
3733                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
3734                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
3735
3736                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
3737                         assert_eq!(route.paths[0][1].short_channel_id, 13);
3738                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
3739                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
3740                         assert_eq!(route.paths[0][1].node_features.le_flags(), InvoiceFeatures::known().le_flags());
3741                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
3742                 }
3743         }
3744
3745         /// Tries to open a network graph file, or panics with a URL to fetch it.
3746         pub(super) fn get_route_file() -> std::fs::File {
3747                 File::open("net_graph-2021-02-12.bin") // By default we're run in RL/lightning
3748                         .or_else(|_| File::open("lightning/net_graph-2021-02-12.bin")) // We may be run manually in RL/
3749                         .or_else(|_| { // Fall back to guessing based on the binary location
3750                                 // path is likely something like .../rust-lightning/target/debug/deps/lightning-...
3751                                 let mut path = std::env::current_exe().unwrap();
3752                                 path.pop(); // lightning-...
3753                                 path.pop(); // deps
3754                                 path.pop(); // debug
3755                                 path.pop(); // target
3756                                 path.push("lightning");
3757                                 path.push("net_graph-2021-02-12.bin");
3758                                 eprintln!("{}", path.to_str().unwrap());
3759                                 File::open(path)
3760                         })
3761                         .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")
3762         }
3763
3764         pub(super) fn random_init_seed() -> u64 {
3765                 // Because the default HashMap in std pulls OS randomness, we can use it as a (bad) RNG.
3766                 use std::hash::{BuildHasher, Hasher};
3767                 let seed = std::collections::hash_map::RandomState::new().build_hasher().finish();
3768                 println!("Using seed of {}", seed);
3769                 seed
3770         }
3771
3772         use std::fs::File;
3773         use util::ser::Readable;
3774         #[test]
3775         fn generate_routes() {
3776                 let mut d = get_route_file();
3777                 let graph = NetworkGraph::read(&mut d).unwrap();
3778
3779                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3780                 let mut seed = random_init_seed() as usize;
3781                 'load_endpoints: for _ in 0..10 {
3782                         loop {
3783                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3784                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3785                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3786                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3787                                 let amt = seed as u64 % 200_000_000;
3788                                 if get_route(src, &graph, dst, None, None, &[], amt, 42, &test_utils::TestLogger::new()).is_ok() {
3789                                         continue 'load_endpoints;
3790                                 }
3791                         }
3792                 }
3793         }
3794
3795         #[test]
3796         fn generate_routes_mpp() {
3797                 let mut d = get_route_file();
3798                 let graph = NetworkGraph::read(&mut d).unwrap();
3799
3800                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3801                 let mut seed = random_init_seed() as usize;
3802                 'load_endpoints: for _ in 0..10 {
3803                         loop {
3804                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3805                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3806                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3807                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3808                                 let amt = seed as u64 % 200_000_000;
3809                                 if get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &test_utils::TestLogger::new()).is_ok() {
3810                                         continue 'load_endpoints;
3811                                 }
3812                         }
3813                 }
3814         }
3815 }
3816
3817 #[cfg(all(test, feature = "unstable"))]
3818 mod benches {
3819         use super::*;
3820         use util::logger::{Logger, Record};
3821
3822         use std::fs::File;
3823         use test::Bencher;
3824
3825         struct DummyLogger {}
3826         impl Logger for DummyLogger {
3827                 fn log(&self, _record: &Record) {}
3828         }
3829
3830         #[bench]
3831         fn generate_routes(bench: &mut Bencher) {
3832                 let mut d = tests::get_route_file();
3833                 let graph = NetworkGraph::read(&mut d).unwrap();
3834
3835                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3836                 let mut path_endpoints = Vec::new();
3837                 let mut seed: usize = 0xdeadbeef;
3838                 'load_endpoints: for _ in 0..100 {
3839                         loop {
3840                                 seed *= 0xdeadbeef;
3841                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3842                                 seed *= 0xdeadbeef;
3843                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3844                                 let amt = seed as u64 % 1_000_000;
3845                                 if get_route(src, &graph, dst, None, None, &[], amt, 42, &DummyLogger{}).is_ok() {
3846                                         path_endpoints.push((src, dst, amt));
3847                                         continue 'load_endpoints;
3848                                 }
3849                         }
3850                 }
3851
3852                 // ...then benchmark finding paths between the nodes we learned.
3853                 let mut idx = 0;
3854                 bench.iter(|| {
3855                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
3856                         assert!(get_route(src, &graph, dst, None, None, &[], amt, 42, &DummyLogger{}).is_ok());
3857                         idx += 1;
3858                 });
3859         }
3860
3861         #[bench]
3862         fn generate_mpp_routes(bench: &mut Bencher) {
3863                 let mut d = tests::get_route_file();
3864                 let graph = NetworkGraph::read(&mut d).unwrap();
3865
3866                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3867                 let mut path_endpoints = Vec::new();
3868                 let mut seed: usize = 0xdeadbeef;
3869                 'load_endpoints: for _ in 0..100 {
3870                         loop {
3871                                 seed *= 0xdeadbeef;
3872                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3873                                 seed *= 0xdeadbeef;
3874                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3875                                 let amt = seed as u64 % 1_000_000;
3876                                 if get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &DummyLogger{}).is_ok() {
3877                                         path_endpoints.push((src, dst, amt));
3878                                         continue 'load_endpoints;
3879                                 }
3880                         }
3881                 }
3882
3883                 // ...then benchmark finding paths between the nodes we learned.
3884                 let mut idx = 0;
3885                 bench.iter(|| {
3886                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
3887                         assert!(get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &DummyLogger{}).is_ok());
3888                         idx += 1;
3889                 });
3890         }
3891 }