_ 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 effective htlc_minimum_msat at this hop. If a later hop on the path had a higher HTLC
 148         /// minimum, we use it, plus the fees required at each earlier hop to meet it.
 149         path_htlc_minimum_msat: u64,
 150 }
 151
 152 impl cmp::Ord for RouteGraphNode {
 153         fn cmp(&self, other: &RouteGraphNode) -> cmp::Ordering {
 154                 let other_score = cmp::max(other.lowest_fee_to_peer_through_node, other.path_htlc_minimum_msat);
 155                 let self_score = cmp::max(self.lowest_fee_to_peer_through_node, self.path_htlc_minimum_msat);
 156                 other_score.cmp(&self_score).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<'a> {
 179         // The RouteHint fields which will eventually be used if this hop is used in a final Route.
 180         // Note that node_features is calculated separately after our initial graph walk.
 181         pubkey: PublicKey,
 182         short_channel_id: u64,
 183         channel_features: &'a ChannelFeatures,
 184         fee_msat: u64,
 185         cltv_expiry_delta: u32,
 186
 187         /// Minimal fees required to route to the source node of the current hop via any of its inbound channels.
 188         src_lowest_inbound_fees: RoutingFees,
 189         /// Fees of the channel used in this hop.
 190         channel_fees: RoutingFees,
 191         /// All the fees paid *after* this channel on the way to the destination
 192         next_hops_fee_msat: u64,
 193         /// Fee paid for the use of the current channel (see channel_fees).
 194         /// The value will be actually deducted from the counterparty balance on the previous link.
 195         hop_use_fee_msat: u64,
 196         /// Used to compare channels when choosing the for routing.
 197         /// Includes paying for the use of a hop and the following hops, as well as
 198         /// an estimated cost of reaching this hop.
 199         /// Might get stale when fees are recomputed. Primarily for internal use.
 200         total_fee_msat: u64,
 201         /// This is useful for update_value_and_recompute_fees to make sure
 202         /// we don't fall below the minimum. Should not be updated manually and
 203         /// generally should not be accessed.
 204         htlc_minimum_msat: u64,
 205         /// A mirror of the same field in RouteGraphNode. Note that this is only used during the graph
 206         /// walk and may be invalid thereafter.
 207         path_htlc_minimum_msat: u64,
 208         /// If we've already processed a node as the best node, we shouldn't process it again. Normally
 209         /// we'd just ignore it if we did as all channels would have a higher new fee, but because we
 210         /// may decrease the amounts in use as we walk the graph, the actual calculated fee may
 211         /// decrease as well. Thus, we have to explicitly track which nodes have been processed and
 212         /// avoid processing them again.
 213         was_processed: bool,
 214         #[cfg(any(test, feature = "fuzztarget"))]
 215         // In tests, we apply further sanity checks on cases where we skip nodes we already processed
 216         // to ensure it is specifically in cases where the fee has gone down because of a decrease in
 217         // value_contribution_msat, which requires tracking it here. See comments below where it is
 218         // used for more info.
 219         value_contribution_msat: u64,
 220 }
 221
 222 // Instantiated with a list of hops with correct data in them collected during path finding,
 223 // an instance of this struct should be further modified only via given methods.
 224 #[derive(Clone)]
 225 struct PaymentPath<'a> {
 226         hops: Vec<(PathBuildingHop<'a>, NodeFeatures)>,
 227 }
 228
 229 impl<'a> PaymentPath<'a> {
 230         // TODO: Add a value_msat field to PaymentPath and use it instead of this function.
 231         fn get_value_msat(&self) -> u64 {
 232                 self.hops.last().unwrap().0.fee_msat
 233         }
 234
 235         fn get_total_fee_paid_msat(&self) -> u64 {
 236                 if self.hops.len() < 1 {
 237                         return 0;
 238                 }
 239                 let mut result = 0;
 240                 // Can't use next_hops_fee_msat because it gets outdated.
 241                 for (i, (hop, _)) in self.hops.iter().enumerate() {
 242                         if i != self.hops.len() - 1 {
 243                                 result += hop.fee_msat;
 244                         }
 245                 }
 246                 return result;
 247         }
 248
 249         // If the amount transferred by the path is updated, the fees should be adjusted. Any other way
 250         // to change fees may result in an inconsistency.
 251         //
 252         // Sometimes we call this function right after constructing a path which is inconsistent in
 253         // that it the value being transferred has decreased while we were doing path finding, leading
 254         // to the fees being paid not lining up with the actual limits.
 255         //
 256         // Note that this function is not aware of the available_liquidity limit, and thus does not
 257         // support increasing the value being transferred.
 258         fn update_value_and_recompute_fees(&mut self, value_msat: u64) {
 259                 assert!(value_msat <= self.hops.last().unwrap().0.fee_msat);
 260
 261                 let mut total_fee_paid_msat = 0 as u64;
 262                 for i in (0..self.hops.len()).rev() {
 263                         let last_hop = i == self.hops.len() - 1;
 264
 265                         // For non-last-hop, this value will represent the fees paid on the current hop. It
 266                         // will consist of the fees for the use of the next hop, and extra fees to match
 267                         // htlc_minimum_msat of the current channel. Last hop is handled separately.
 268                         let mut cur_hop_fees_msat = 0;
 269                         if !last_hop {
 270                                 cur_hop_fees_msat = self.hops.get(i + 1).unwrap().0.hop_use_fee_msat;
 271                         }
 272
 273                         let mut cur_hop = &mut self.hops.get_mut(i).unwrap().0;
 274                         cur_hop.next_hops_fee_msat = total_fee_paid_msat;
 275                         // Overpay in fees if we can't save these funds due to htlc_minimum_msat.
 276                         // We try to account for htlc_minimum_msat in scoring (add_entry!), so that nodes don't
 277                         // set it too high just to maliciously take more fees by exploiting this
 278                         // match htlc_minimum_msat logic.
 279                         let mut cur_hop_transferred_amount_msat = total_fee_paid_msat + value_msat;
 280                         if let Some(extra_fees_msat) = cur_hop.htlc_minimum_msat.checked_sub(cur_hop_transferred_amount_msat) {
 281                                 // Note that there is a risk that *previous hops* (those closer to us, as we go
 282                                 // payee->our_node here) would exceed their htlc_maximum_msat or available balance.
 283                                 //
 284                                 // This might make us end up with a broken route, although this should be super-rare
 285                                 // in practice, both because of how healthy channels look like, and how we pick
 286                                 // channels in add_entry.
 287                                 // Also, this can't be exploited more heavily than *announce a free path and fail
 288                                 // all payments*.
 289                                 cur_hop_transferred_amount_msat += extra_fees_msat;
 290                                 total_fee_paid_msat += extra_fees_msat;
 291                                 cur_hop_fees_msat += extra_fees_msat;
 292                         }
 293
 294                         if last_hop {
 295                                 // Final hop is a special case: it usually has just value_msat (by design), but also
 296                                 // it still could overpay for the htlc_minimum_msat.
 297                                 cur_hop.fee_msat = cur_hop_transferred_amount_msat;
 298                         } else {
 299                                 // Propagate updated fees for the use of the channels to one hop back, where they
 300                                 // will be actually paid (fee_msat). The last hop is handled above separately.
 301                                 cur_hop.fee_msat = cur_hop_fees_msat;
 302                         }
 303
 304                         // Fee for the use of the current hop which will be deducted on the previous hop.
 305                         // Irrelevant for the first hop, as it doesn't have the previous hop, and the use of
 306                         // this channel is free for us.
 307                         if i != 0 {
 308                                 if let Some(new_fee) = compute_fees(cur_hop_transferred_amount_msat, cur_hop.channel_fees) {
 309                                         cur_hop.hop_use_fee_msat = new_fee;
 310                                         total_fee_paid_msat += new_fee;
 311                                 } else {
 312                                         // It should not be possible because this function is called only to reduce the
 313                                         // value. In that case, compute_fee was already called with the same fees for
 314                                         // larger amount and there was no overflow.
 315                                         unreachable!();
 316                                 }
 317                         }
 318                 }
 319         }
 320 }
 321
 322 fn compute_fees(amount_msat: u64, channel_fees: RoutingFees) -> Option<u64> {
 323         let proportional_fee_millions =
 324                 amount_msat.checked_mul(channel_fees.proportional_millionths as u64);
 325         if let Some(new_fee) = proportional_fee_millions.and_then(|part| {
 326                         (channel_fees.base_msat as u64).checked_add(part / 1_000_000) }) {
 327
 328                 Some(new_fee)
 329         } else {
 330                 // This function may be (indirectly) called without any verification,
 331                 // with channel_fees provided by a caller. We should handle it gracefully.
 332                 None
 333         }
 334 }
 335
 336 /// Gets a route from us (payer) to the given target node (payee).
 337 ///
 338 /// If the payee provided features in their invoice, they should be provided via payee_features.
 339 /// Without this, MPP will only be used if the payee's features are available in the network graph.
 340 ///
 341 /// Extra routing hops between known nodes and the target will be used if they are included in
 342 /// last_hops.
 343 ///
 344 /// If some channels aren't announced, it may be useful to fill in a first_hops with the
 345 /// results from a local ChannelManager::list_usable_channels() call. If it is filled in, our
 346 /// view of our local channels (from net_graph_msg_handler) will be ignored, and only those
 347 /// in first_hops will be used.
 348 ///
 349 /// Panics if first_hops contains channels without short_channel_ids
 350 /// (ChannelManager::list_usable_channels will never include such channels).
 351 ///
 352 /// The fees on channels from us to next-hops are ignored (as they are assumed to all be
 353 /// equal), however the enabled/disabled bit on such channels as well as the
 354 /// htlc_minimum_msat/htlc_maximum_msat *are* checked as they may change based on the receiving node.
 355 pub fn get_route<L: Deref>(our_node_id: &PublicKey, network: &NetworkGraph, payee: &PublicKey, payee_features: Option<InvoiceFeatures>, first_hops: Option<&[&ChannelDetails]>,
 356         last_hops: &[&RouteHint], final_value_msat: u64, final_cltv: u32, logger: L) -> Result<Route, LightningError> where L::Target: Logger {
 357         // TODO: Obviously *only* using total fee cost sucks. We should consider weighting by
 358         // uptime/success in using a node in the past.
 359         if *payee == *our_node_id {
 360                 return Err(LightningError{err: "Cannot generate a route to ourselves".to_owned(), action: ErrorAction::IgnoreError});
 361         }
 362
 363         if final_value_msat > MAX_VALUE_MSAT {
 364                 return Err(LightningError{err: "Cannot generate a route of more value than all existing satoshis".to_owned(), action: ErrorAction::IgnoreError});
 365         }
 366
 367         if final_value_msat == 0 {
 368                 return Err(LightningError{err: "Cannot send a payment of 0 msat".to_owned(), action: ErrorAction::IgnoreError});
 369         }
 370
 371         for last_hop in last_hops {
 372                 if last_hop.src_node_id == *payee {
 373                         return Err(LightningError{err: "Last hop cannot have a payee as a source.".to_owned(), action: ErrorAction::IgnoreError});
 374                 }
 375         }
 376
 377         // The general routing idea is the following:
 378         // 1. Fill first/last hops communicated by the caller.
 379         // 2. Attempt to construct a path from payer to payee for transferring
 380         //    any ~sufficient (described later) value.
 381         //    If succeed, remember which channels were used and how much liquidity they have available,
 382         //    so that future paths don't rely on the same liquidity.
 383         // 3. Prooceed to the next step if:
 384         //    - we hit the recommended target value;
 385         //    - OR if we could not construct a new path. Any next attempt will fail too.
 386         //    Otherwise, repeat step 2.
 387         // 4. See if we managed to collect paths which aggregately are able to transfer target value
 388         //    (not recommended value). If yes, proceed. If not, fail routing.
 389         // 5. Randomly combine paths into routes having enough to fulfill the payment. (TODO: knapsack)
 390         // 6. Of all the found paths, select only those with the lowest total fee.
 391         // 7. The last path in every selected route is likely to be more than we need.
 392         //    Reduce its value-to-transfer and recompute fees.
 393         // 8. Choose the best route by the lowest total fee.
 394
 395         // As for the actual search algorithm,
 396         // we do a payee-to-payer pseudo-Dijkstra's sorting by each node's distance from the payee
 397         // plus the minimum per-HTLC fee to get from it to another node (aka "shitty pseudo-A*").
 398         //
 399         // We are not a faithful Dijkstra's implementation because we can change values which impact
 400         // earlier nodes while processing later nodes. Specifically, if we reach a channel with a lower
 401         // liquidity limit (via htlc_maximum_msat, on-chain capacity or assumed liquidity limits) then
 402         // the value we are currently attempting to send over a path, we simply reduce the value being
 403         // sent along the path for any hops after that channel. This may imply that later fees (which
 404         // we've already tabulated) are lower because a smaller value is passing through the channels
 405         // (and the proportional fee is thus lower). There isn't a trivial way to recalculate the
 406         // channels which were selected earlier (and which may still be used for other paths without a
 407         // lower liquidity limit), so we simply accept that some liquidity-limited paths may be
 408         // de-preferenced.
 409         //
 410         // One potentially problematic case for this algorithm would be if there are many
 411         // liquidity-limited paths which are liquidity-limited near the destination (ie early in our
 412         // graph walking), we may never find a path which is not liquidity-limited and has lower
 413         // proportional fee (and only lower absolute fee when considering the ultimate value sent).
 414         // Because we only consider paths with at least 5% of the total value being sent, the damage
 415         // from such a case should be limited, however this could be further reduced in the future by
 416         // calculating fees on the amount we wish to route over a path, ie ignoring the liquidity
 417         // limits for the purposes of fee calculation.
 418         //
 419         // Alternatively, we could store more detailed path information in the heap (targets, below)
 420         // and index the best-path map (dist, below) by node *and* HTLC limits, however that would blow
 421         // up the runtime significantly both algorithmically (as we'd traverse nodes multiple times)
 422         // and practically (as we would need to store dynamically-allocated path information in heap
 423         // objects, increasing malloc traffic and indirect memory access significantly). Further, the
 424         // results of such an algorithm would likely be biased towards lower-value paths.
 425         //
 426         // Further, we could return to a faithful Dijkstra's algorithm by rejecting paths with limits
 427         // outside of our current search value, running a path search more times to gather candidate
 428         // paths at different values. While this may be acceptable, further path searches may increase
 429         // runtime for little gain. Specifically, the current algorithm rather efficiently explores the
 430         // graph for candidate paths, calculating the maximum value which can realistically be sent at
 431         // the same time, remaining generic across different payment values.
 432         //
 433         // TODO: There are a few tweaks we could do, including possibly pre-calculating more stuff
 434         // to use as the A* heuristic beyond just the cost to get one node further than the current
 435         // one.
 436
 437         let dummy_directional_info = DummyDirectionalChannelInfo { // used for first_hops routes
 438                 cltv_expiry_delta: 0,
 439                 htlc_minimum_msat: 0,
 440                 htlc_maximum_msat: None,
 441                 fees: RoutingFees {
 442                         base_msat: 0,
 443                         proportional_millionths: 0,
 444                 }
 445         };
 446
 447         // Allow MPP only if we have a features set from somewhere that indicates the payee supports
 448         // it. If the payee supports it they're supposed to include it in the invoice, so that should
 449         // work reliably.
 450         let allow_mpp = if let Some(features) = &payee_features {
 451                 features.supports_basic_mpp()
 452         } else if let Some(node) = network.get_nodes().get(&payee) {
 453                 if let Some(node_info) = node.announcement_info.as_ref() {
 454                         node_info.features.supports_basic_mpp()
 455                 } else { false }
 456         } else { false };
 457
 458         // Step (1).
 459         // Prepare the data we'll use for payee-to-payer search by
 460         // inserting first hops suggested by the caller as targets.
 461         // Our search will then attempt to reach them while traversing from the payee node.
 462         let mut first_hop_targets: HashMap<_, (_, ChannelFeatures, _, NodeFeatures)> =
 463                 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.to_context(), chan.outbound_capacity_msat, chan.counterparty_features.to_context()));
 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         let empty_channel_features = ChannelFeatures::empty();
 478
 479         // The main heap containing all candidate next-hops sorted by their score (max(A* fee,
 480         // htlc_minimum)). Ideally this would be a heap which allowed cheap score reduction instead of
 481         // adding duplicate entries when we find a better path to a given node.
 482         let mut targets = BinaryHeap::new();
 483
 484         // Map from node_id to information about the best current path to that node, including feerate
 485         // information.
 486         let mut dist = HashMap::with_capacity(network.get_nodes().len());
 487
 488         // During routing, if we ignore a path due to an htlc_minimum_msat limit, we set this,
 489         // indicating that we may wish to try again with a higher value, potentially paying to meet an
 490         // htlc_minimum with extra fees while still finding a cheaper path.
 491         let mut hit_minimum_limit;
 492
 493         // When arranging a route, we select multiple paths so that we can make a multi-path payment.
 494         // We start with a path_value of the exact amount we want, and if that generates a route we may
 495         // return it immediately. Otherwise, we don't stop searching for paths until we have 3x the
 496         // amount we want in total across paths, selecting the best subset at the end.
 497         const ROUTE_CAPACITY_PROVISION_FACTOR: u64 = 3;
 498         let recommended_value_msat = final_value_msat * ROUTE_CAPACITY_PROVISION_FACTOR as u64;
 499         let mut path_value_msat = final_value_msat;
 500
 501         // We don't want multiple paths (as per MPP) share liquidity of the same channels.
 502         // This map allows paths to be aware of the channel use by other paths in the same call.
 503         // This would help to make a better path finding decisions and not "overbook" channels.
 504         // It is unaware of the directions (except for `outbound_capacity_msat` in `first_hops`).
 505         let mut bookkeeped_channels_liquidity_available_msat = HashMap::with_capacity(network.get_nodes().len());
 506
 507         // Keeping track of how much value we already collected across other paths. Helps to decide:
 508         // - how much a new path should be transferring (upper bound);
 509         // - whether a channel should be disregarded because
 510         //   it's available liquidity is too small comparing to how much more we need to collect;
 511         // - when we want to stop looking for new paths.
 512         let mut already_collected_value_msat = 0;
 513
 514         macro_rules! add_entry {
 515                 // Adds entry which goes from $src_node_id to $dest_node_id
 516                 // over the channel with id $chan_id with fees described in
 517                 // $directional_info.
 518                 // $next_hops_fee_msat represents the fees paid for using all the channel *after* this one,
 519                 // since that value has to be transferred over this channel.
 520                 ( $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,
 521                    $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr ) => {
 522                         // Channels to self should not be used. This is more of belt-and-suspenders, because in
 523                         // practice these cases should be caught earlier:
 524                         // - for regular channels at channel announcement (TODO)
 525                         // - for first and last hops early in get_route
 526                         if $src_node_id != $dest_node_id.clone() {
 527                                 let available_liquidity_msat = bookkeeped_channels_liquidity_available_msat.entry($chan_id.clone()).or_insert_with(|| {
 528                                         let mut initial_liquidity_available_msat = None;
 529                                         if let Some(capacity_sats) = $capacity_sats {
 530                                                 initial_liquidity_available_msat = Some(capacity_sats * 1000);
 531                                         }
 532
 533                                         if let Some(htlc_maximum_msat) = $directional_info.htlc_maximum_msat {
 534                                                 if let Some(available_msat) = initial_liquidity_available_msat {
 535                                                         initial_liquidity_available_msat = Some(cmp::min(available_msat, htlc_maximum_msat));
 536                                                 } else {
 537                                                         initial_liquidity_available_msat = Some(htlc_maximum_msat);
 538                                                 }
 539                                         }
 540
 541                                         match initial_liquidity_available_msat {
 542                                                 Some(available_msat) => available_msat,
 543                                                 // We assume channels with unknown balance have
 544                                                 // a capacity of 0.0025 BTC (or 250_000 sats).
 545                                                 None => 250_000 * 1000
 546                                         }
 547                                 });
 548
 549                                 // It is tricky to substract $next_hops_fee_msat from available liquidity here.
 550                                 // It may be misleading because we might later choose to reduce the value transferred
 551                                 // over these channels, and the channel which was insufficient might become sufficient.
 552                                 // Worst case: we drop a good channel here because it can't cover the high following
 553                                 // fees caused by one expensive channel, but then this channel could have been used
 554                                 // if the amount being transferred over this path is lower.
 555                                 // We do this for now, but this is a subject for removal.
 556                                 if let Some(available_value_contribution_msat) = available_liquidity_msat.checked_sub($next_hops_fee_msat) {
 557
 558                                         // Routing Fragmentation Mitigation heuristic:
 559                                         //
 560                                         // Routing fragmentation across many payment paths increases the overall routing
 561                                         // fees as you have irreducible routing fees per-link used (`fee_base_msat`).
 562                                         // Taking too many smaller paths also increases the chance of payment failure.
 563                                         // Thus to avoid this effect, we require from our collected links to provide
 564                                         // at least a minimal contribution to the recommended value yet-to-be-fulfilled.
 565                                         //
 566                                         // This requirement is currently 5% of the remaining-to-be-collected value.
 567                                         // This means as we successfully advance in our collection,
 568                                         // the absolute liquidity contribution is lowered,
 569                                         // thus increasing the number of potential channels to be selected.
 570
 571                                         // Derive the minimal liquidity contribution with a ratio of 20 (5%, rounded up)
 572                                         // or 100% if we're not allowed to do multipath payments.
 573                                         let minimal_value_contribution_msat: u64 = if allow_mpp {
 574                                                 (recommended_value_msat - already_collected_value_msat + 19) / 20
 575                                         } else {
 576                                                 final_value_msat
 577                                         };
 578                                         // Verify the liquidity offered by this channel complies to the minimal contribution.
 579                                         let contributes_sufficient_value = available_value_contribution_msat >= minimal_value_contribution_msat;
 580
 581                                         let value_contribution_msat = cmp::min(available_value_contribution_msat, $next_hops_value_contribution);
 582                                         // Includes paying fees for the use of the following channels.
 583                                         let amount_to_transfer_over_msat: u64 = match value_contribution_msat.checked_add($next_hops_fee_msat) {
 584                                                 Some(result) => result,
 585                                                 // Can't overflow due to how the values were computed right above.
 586                                                 None => unreachable!(),
 587                                         };
 588                                         #[allow(unused_comparisons)] // $next_hops_path_htlc_minimum_msat is 0 in some calls so rustc complains
 589                                         let over_path_minimum_msat = amount_to_transfer_over_msat >= $directional_info.htlc_minimum_msat &&
 590                                                 amount_to_transfer_over_msat >= $next_hops_path_htlc_minimum_msat;
 591
 592                                         // If HTLC minimum is larger than the amount we're going to transfer, we shouldn't
 593                                         // bother considering this channel.
 594                                         // Since we're choosing amount_to_transfer_over_msat as maximum possible, it can
 595                                         // be only reduced later (not increased), so this channel should just be skipped
 596                                         // as not sufficient.
 597                                         if !over_path_minimum_msat {
 598                                                 hit_minimum_limit = true;
 599                                         } else if contributes_sufficient_value {
 600                                                 // Note that low contribution here (limited by available_liquidity_msat)
 601                                                 // might violate htlc_minimum_msat on the hops which are next along the
 602                                                 // payment path (upstream to the payee). To avoid that, we recompute path
 603                                                 // path fees knowing the final path contribution after constructing it.
 604                                                 let path_htlc_minimum_msat = match compute_fees($next_hops_path_htlc_minimum_msat, $directional_info.fees)
 605                                                                 .map(|fee_msat| fee_msat.checked_add($next_hops_path_htlc_minimum_msat)) {
 606                                                         Some(Some(value_msat)) => cmp::max(value_msat, $directional_info.htlc_minimum_msat),
 607                                                         _ => u64::max_value()
 608                                                 };
 609                                                 let hm_entry = dist.entry(&$src_node_id);
 610                                                 let old_entry = hm_entry.or_insert_with(|| {
 611                                                         // If there was previously no known way to access
 612                                                         // the source node (recall it goes payee-to-payer) of $chan_id, first add
 613                                                         // a semi-dummy record just to compute the fees to reach the source node.
 614                                                         // This will affect our decision on selecting $chan_id
 615                                                         // as a way to reach the $dest_node_id.
 616                                                         let mut fee_base_msat = u32::max_value();
 617                                                         let mut fee_proportional_millionths = u32::max_value();
 618                                                         if let Some(Some(fees)) = network.get_nodes().get(&$src_node_id).map(|node| node.lowest_inbound_channel_fees) {
 619                                                                 fee_base_msat = fees.base_msat;
 620                                                                 fee_proportional_millionths = fees.proportional_millionths;
 621                                                         }
 622                                                         PathBuildingHop {
 623                                                                 pubkey: $dest_node_id.clone(),
 624                                                                 short_channel_id: 0,
 625                                                                 channel_features: $chan_features,
 626                                                                 fee_msat: 0,
 627                                                                 cltv_expiry_delta: 0,
 628                                                                 src_lowest_inbound_fees: RoutingFees {
 629                                                                         base_msat: fee_base_msat,
 630                                                                         proportional_millionths: fee_proportional_millionths,
 631                                                                 },
 632                                                                 channel_fees: $directional_info.fees,
 633                                                                 next_hops_fee_msat: u64::max_value(),
 634                                                                 hop_use_fee_msat: u64::max_value(),
 635                                                                 total_fee_msat: u64::max_value(),
 636                                                                 htlc_minimum_msat: $directional_info.htlc_minimum_msat,
 637                                                                 path_htlc_minimum_msat,
 638                                                                 was_processed: false,
 639                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 640                                                                 value_contribution_msat,
 641                                                         }
 642                                                 });
 643
 644                                                 #[allow(unused_mut)] // We only use the mut in cfg(test)
 645                                                 let mut should_process = !old_entry.was_processed;
 646                                                 #[cfg(any(test, feature = "fuzztarget"))]
 647                                                 {
 648                                                         // In test/fuzzing builds, we do extra checks to make sure the skipping
 649                                                         // of already-seen nodes only happens in cases we expect (see below).
 650                                                         if !should_process { should_process = true; }
 651                                                 }
 652
 653                                                 if should_process {
 654                                                         let mut hop_use_fee_msat = 0;
 655                                                         let mut total_fee_msat = $next_hops_fee_msat;
 656
 657                                                         // Ignore hop_use_fee_msat for channel-from-us as we assume all channels-from-us
 658                                                         // will have the same effective-fee
 659                                                         if $src_node_id != *our_node_id {
 660                                                                 match compute_fees(amount_to_transfer_over_msat, $directional_info.fees) {
 661                                                                         // max_value means we'll always fail
 662                                                                         // the old_entry.total_fee_msat > total_fee_msat check
 663                                                                         None => total_fee_msat = u64::max_value(),
 664                                                                         Some(fee_msat) => {
 665                                                                                 hop_use_fee_msat = fee_msat;
 666                                                                                 total_fee_msat += hop_use_fee_msat;
 667                                                                                 // When calculating the lowest inbound fees to a node, we
 668                                                                                 // calculate fees here not based on the actual value we think
 669                                                                                 // will flow over this channel, but on the minimum value that
 670                                                                                 // we'll accept flowing over it. The minimum accepted value
 671                                                                                 // is a constant through each path collection run, ensuring
 672                                                                                 // consistent basis. Otherwise we may later find a
 673                                                                                 // different path to the source node that is more expensive,
 674                                                                                 // but which we consider to be cheaper because we are capacity
 675                                                                                 // constrained and the relative fee becomes lower.
 676                                                                                 match compute_fees(minimal_value_contribution_msat, old_entry.src_lowest_inbound_fees)
 677                                                                                                 .map(|a| a.checked_add(total_fee_msat)) {
 678                                                                                         Some(Some(v)) => {
 679                                                                                                 total_fee_msat = v;
 680                                                                                         },
 681                                                                                         _ => {
 682                                                                                                 total_fee_msat = u64::max_value();
 683                                                                                         }
 684                                                                                 };
 685                                                                         }
 686                                                                 }
 687                                                         }
 688
 689                                                         let new_graph_node = RouteGraphNode {
 690                                                                 pubkey: $src_node_id,
 691                                                                 lowest_fee_to_peer_through_node: total_fee_msat,
 692                                                                 lowest_fee_to_node: $next_hops_fee_msat as u64 + hop_use_fee_msat,
 693                                                                 value_contribution_msat: value_contribution_msat,
 694                                                                 path_htlc_minimum_msat,
 695                                                         };
 696
 697                                                         // Update the way of reaching $src_node_id with the given $chan_id (from $dest_node_id),
 698                                                         // if this way is cheaper than the already known
 699                                                         // (considering the cost to "reach" this channel from the route destination,
 700                                                         // the cost of using this channel,
 701                                                         // and the cost of routing to the source node of this channel).
 702                                                         // Also, consider that htlc_minimum_msat_difference, because we might end up
 703                                                         // paying it. Consider the following exploit:
 704                                                         // we use 2 paths to transfer 1.5 BTC. One of them is 0-fee normal 1 BTC path,
 705                                                         // and for the other one we picked a 1sat-fee path with htlc_minimum_msat of
 706                                                         // 1 BTC. Now, since the latter is more expensive, we gonna try to cut it
 707                                                         // by 0.5 BTC, but then match htlc_minimum_msat by paying a fee of 0.5 BTC
 708                                                         // to this channel.
 709                                                         // Ideally the scoring could be smarter (e.g. 0.5*htlc_minimum_msat here),
 710                                                         // but it may require additional tracking - we don't want to double-count
 711                                                         // the fees included in $next_hops_path_htlc_minimum_msat, but also
 712                                                         // can't use something that may decrease on future hops.
 713                                                         let old_cost = cmp::max(old_entry.total_fee_msat, old_entry.path_htlc_minimum_msat);
 714                                                         let new_cost = cmp::max(total_fee_msat, path_htlc_minimum_msat);
 715
 716                                                         if !old_entry.was_processed && new_cost < old_cost {
 717                                                                 targets.push(new_graph_node);
 718                                                                 old_entry.next_hops_fee_msat = $next_hops_fee_msat;
 719                                                                 old_entry.hop_use_fee_msat = hop_use_fee_msat;
 720                                                                 old_entry.total_fee_msat = total_fee_msat;
 721                                                                 old_entry.pubkey = $dest_node_id.clone();
 722                                                                 old_entry.short_channel_id = $chan_id.clone();
 723                                                                 old_entry.channel_features = $chan_features;
 724                                                                 old_entry.fee_msat = 0; // This value will be later filled with hop_use_fee_msat of the following channel
 725                                                                 old_entry.cltv_expiry_delta = $directional_info.cltv_expiry_delta as u32;
 726                                                                 old_entry.channel_fees = $directional_info.fees;
 727                                                                 old_entry.htlc_minimum_msat = $directional_info.htlc_minimum_msat;
 728                                                                 old_entry.path_htlc_minimum_msat = path_htlc_minimum_msat;
 729                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 730                                                                 {
 731                                                                         old_entry.value_contribution_msat = value_contribution_msat;
 732                                                                 }
 733                                                         } else if old_entry.was_processed && new_cost < old_cost {
 734                                                                 #[cfg(any(test, feature = "fuzztarget"))]
 735                                                                 {
 736                                                                         // If we're skipping processing a node which was previously
 737                                                                         // processed even though we found another path to it with a
 738                                                                         // cheaper fee, check that it was because the second path we
 739                                                                         // found (which we are processing now) has a lower value
 740                                                                         // contribution due to an HTLC minimum limit.
 741                                                                         //
 742                                                                         // e.g. take a graph with two paths from node 1 to node 2, one
 743                                                                         // through channel A, and one through channel B. Channel A and
 744                                                                         // B are both in the to-process heap, with their scores set by
 745                                                                         // a higher htlc_minimum than fee.
 746                                                                         // Channel A is processed first, and the channels onwards from
 747                                                                         // node 1 are added to the to-process heap. Thereafter, we pop
 748                                                                         // Channel B off of the heap, note that it has a much more
 749                                                                         // restrictive htlc_maximum_msat, and recalculate the fees for
 750                                                                         // all of node 1's channels using the new, reduced, amount.
 751                                                                         //
 752                                                                         // This would be bogus - we'd be selecting a higher-fee path
 753                                                                         // with a lower htlc_maximum_msat instead of the one we'd
 754                                                                         // already decided to use.
 755                                                                         debug_assert!(path_htlc_minimum_msat < old_entry.path_htlc_minimum_msat);
 756                                                                         debug_assert!(value_contribution_msat < old_entry.value_contribution_msat);
 757                                                                 }
 758                                                         }
 759                                                 }
 760                                         }
 761                                 }
 762                         }
 763                 };
 764         }
 765
 766         let empty_node_features = NodeFeatures::empty();
 767         // Find ways (channels with destination) to reach a given node and store them
 768         // in the corresponding data structures (routing graph etc).
 769         // $fee_to_target_msat represents how much it costs to reach to this node from the payee,
 770         // meaning how much will be paid in fees after this node (to the best of our knowledge).
 771         // This data can later be helpful to optimize routing (pay lower fees).
 772         macro_rules! add_entries_to_cheapest_to_target_node {
 773                 ( $node: expr, $node_id: expr, $fee_to_target_msat: expr, $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr ) => {
 774                         let skip_node = if let Some(elem) = dist.get_mut($node_id) {
 775                                 let was_processed = elem.was_processed;
 776                                 elem.was_processed = true;
 777                                 was_processed
 778                         } else {
 779                                 // Entries are added to dist in add_entry!() when there is a channel from a node.
 780                                 // Because there are no channels from payee, it will not have a dist entry at this point.
 781                                 // If we're processing any other node, it is always be the result of a channel from it.
 782                                 assert_eq!($node_id, payee);
 783                                 false
 784                         };
 785
 786                         if !skip_node {
 787                                 if first_hops.is_some() {
 788                                         if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat, _)) = first_hop_targets.get(&$node_id) {
 789                                                 add_entry!(first_hop, *our_node_id, $node_id, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, $fee_to_target_msat, $next_hops_value_contribution, $next_hops_path_htlc_minimum_msat);
 790                                         }
 791                                 }
 792
 793                                 let features = if let Some(node_info) = $node.announcement_info.as_ref() {
 794                                         &node_info.features
 795                                 } else {
 796                                         &empty_node_features
 797                                 };
 798
 799                                 if !features.requires_unknown_bits() {
 800                                         for chan_id in $node.channels.iter() {
 801                                                 let chan = network.get_channels().get(chan_id).unwrap();
 802                                                 if !chan.features.requires_unknown_bits() {
 803                                                         if chan.node_one == *$node_id {
 804                                                                 // ie $node is one, ie next hop in A* is two, via the two_to_one channel
 805                                                                 if first_hops.is_none() || chan.node_two != *our_node_id {
 806                                                                         if let Some(two_to_one) = chan.two_to_one.as_ref() {
 807                                                                                 if two_to_one.enabled {
 808                                                                                         add_entry!(chan_id, chan.node_two, chan.node_one, two_to_one, chan.capacity_sats, &chan.features, $fee_to_target_msat, $next_hops_value_contribution, $next_hops_path_htlc_minimum_msat);
 809                                                                                 }
 810                                                                         }
 811                                                                 }
 812                                                         } else {
 813                                                                 if first_hops.is_none() || chan.node_one != *our_node_id {
 814                                                                         if let Some(one_to_two) = chan.one_to_two.as_ref() {
 815                                                                                 if one_to_two.enabled {
 816                                                                                         add_entry!(chan_id, chan.node_one, chan.node_two, one_to_two, chan.capacity_sats, &chan.features, $fee_to_target_msat, $next_hops_value_contribution, $next_hops_path_htlc_minimum_msat);
 817                                                                                 }
 818                                                                         }
 819                                                                 }
 820                                                         }
 821                                                 }
 822                                         }
 823                                 }
 824                         }
 825                 };
 826         }
 827
 828         let mut payment_paths = Vec::<PaymentPath>::new();
 829
 830         // TODO: diversify by nodes (so that all paths aren't doomed if one node is offline).
 831         'paths_collection: loop {
 832                 // For every new path, start from scratch, except
 833                 // bookkeeped_channels_liquidity_available_msat, which will improve
 834                 // the further iterations of path finding. Also don't erase first_hop_targets.
 835                 targets.clear();
 836                 dist.clear();
 837                 hit_minimum_limit = false;
 838
 839                 // If first hop is a private channel and the only way to reach the payee, this is the only
 840                 // place where it could be added.
 841                 if first_hops.is_some() {
 842                         if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat, _)) = first_hop_targets.get(&payee) {
 843                                 add_entry!(first_hop, *our_node_id, payee, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, 0, path_value_msat, 0);
 844                         }
 845                 }
 846
 847                 // Add the payee as a target, so that the payee-to-payer
 848                 // search algorithm knows what to start with.
 849                 match network.get_nodes().get(payee) {
 850                         // The payee is not in our network graph, so nothing to add here.
 851                         // There is still a chance of reaching them via last_hops though,
 852                         // so don't yet fail the payment here.
 853                         // If not, targets.pop() will not even let us enter the loop in step 2.
 854                         None => {},
 855                         Some(node) => {
 856                                 add_entries_to_cheapest_to_target_node!(node, payee, 0, path_value_msat, 0);
 857                         },
 858                 }
 859
 860                 // Step (1).
 861                 // If a caller provided us with last hops, add them to routing targets. Since this happens
 862                 // earlier than general path finding, they will be somewhat prioritized, although currently
 863                 // it matters only if the fees are exactly the same.
 864                 for hop in last_hops.iter() {
 865                         let have_hop_src_in_graph =
 866                                 if let Some(&(ref first_hop, ref features, ref outbound_capacity_msat, _)) = first_hop_targets.get(&hop.src_node_id) {
 867                                         // If this hop connects to a node with which we have a direct channel, ignore
 868                                         // the network graph and add both the hop and our direct channel to
 869                                         // the candidate set.
 870                                         //
 871                                         // Currently there are no channel-context features defined, so we are a
 872                                         // bit lazy here. In the future, we should pull them out via our
 873                                         // ChannelManager, but there's no reason to waste the space until we
 874                                         // need them.
 875                                         add_entry!(first_hop, *our_node_id , hop.src_node_id, dummy_directional_info, Some(outbound_capacity_msat / 1000), features, 0, path_value_msat, 0);
 876                                         true
 877                                 } else {
 878                                         // In any other case, only add the hop if the source is in the regular network
 879                                         // graph:
 880                                         network.get_nodes().get(&hop.src_node_id).is_some()
 881                                 };
 882                         if have_hop_src_in_graph {
 883                                 // BOLT 11 doesn't allow inclusion of features for the last hop hints, which
 884                                 // really sucks, cause we're gonna need that eventually.
 885                                 let last_hop_htlc_minimum_msat: u64 = match hop.htlc_minimum_msat {
 886                                         Some(htlc_minimum_msat) => htlc_minimum_msat,
 887                                         None => 0
 888                                 };
 889                                 let directional_info = DummyDirectionalChannelInfo {
 890                                         cltv_expiry_delta: hop.cltv_expiry_delta as u32,
 891                                         htlc_minimum_msat: last_hop_htlc_minimum_msat,
 892                                         htlc_maximum_msat: hop.htlc_maximum_msat,
 893                                         fees: hop.fees,
 894                                 };
 895                                 add_entry!(hop.short_channel_id, hop.src_node_id, payee, directional_info, None::<u64>, &empty_channel_features, 0, path_value_msat, 0);
 896                         }
 897                 }
 898
 899                 // At this point, targets are filled with the data from first and
 900                 // last hops communicated by the caller, and the payment receiver.
 901                 let mut found_new_path = false;
 902
 903                 // Step (2).
 904                 // If this loop terminates due the exhaustion of targets, two situations are possible:
 905                 // - not enough outgoing liquidity:
 906                 //   0 < already_collected_value_msat < final_value_msat
 907                 // - enough outgoing liquidity:
 908                 //   final_value_msat <= already_collected_value_msat < recommended_value_msat
 909                 // Both these cases (and other cases except reaching recommended_value_msat) mean that
 910                 // paths_collection will be stopped because found_new_path==false.
 911                 // This is not necessarily a routing failure.
 912                 'path_construction: while let Some(RouteGraphNode { pubkey, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat, .. }) = targets.pop() {
 913
 914                         // Since we're going payee-to-payer, hitting our node as a target means we should stop
 915                         // traversing the graph and arrange the path out of what we found.
 916                         if pubkey == *our_node_id {
 917                                 let mut new_entry = dist.remove(&our_node_id).unwrap();
 918                                 let mut ordered_hops = vec!((new_entry.clone(), NodeFeatures::empty()));
 919
 920                                 'path_walk: loop {
 921                                         if let Some(&(_, _, _, ref features)) = first_hop_targets.get(&ordered_hops.last().unwrap().0.pubkey) {
 922                                                 ordered_hops.last_mut().unwrap().1 = features.clone();
 923                                         } else if let Some(node) = network.get_nodes().get(&ordered_hops.last().unwrap().0.pubkey) {
 924                                                 if let Some(node_info) = node.announcement_info.as_ref() {
 925                                                         ordered_hops.last_mut().unwrap().1 = node_info.features.clone();
 926                                                 } else {
 927                                                         ordered_hops.last_mut().unwrap().1 = NodeFeatures::empty();
 928                                                 }
 929                                         } else {
 930                                                 // We should be able to fill in features for everything except the last
 931                                                 // hop, if the last hop was provided via a BOLT 11 invoice (though we
 932                                                 // should be able to extend it further as BOLT 11 does have feature
 933                                                 // flags for the last hop node itself).
 934                                                 assert!(ordered_hops.last().unwrap().0.pubkey == *payee);
 935                                         }
 936
 937                                         // Means we succesfully traversed from the payer to the payee, now
 938                                         // save this path for the payment route. Also, update the liquidity
 939                                         // remaining on the used hops, so that we take them into account
 940                                         // while looking for more paths.
 941                                         if ordered_hops.last().unwrap().0.pubkey == *payee {
 942                                                 break 'path_walk;
 943                                         }
 944
 945                                         new_entry = match dist.remove(&ordered_hops.last().unwrap().0.pubkey) {
 946                                                 Some(payment_hop) => payment_hop,
 947                                                 // We can't arrive at None because, if we ever add an entry to targets,
 948                                                 // we also fill in the entry in dist (see add_entry!).
 949                                                 None => unreachable!(),
 950                                         };
 951                                         // We "propagate" the fees one hop backward (topologically) here,
 952                                         // so that fees paid for a HTLC forwarding on the current channel are
 953                                         // associated with the previous channel (where they will be subtracted).
 954                                         ordered_hops.last_mut().unwrap().0.fee_msat = new_entry.hop_use_fee_msat;
 955                                         ordered_hops.last_mut().unwrap().0.cltv_expiry_delta = new_entry.cltv_expiry_delta;
 956                                         ordered_hops.push((new_entry.clone(), NodeFeatures::empty()));
 957                                 }
 958                                 ordered_hops.last_mut().unwrap().0.fee_msat = value_contribution_msat;
 959                                 ordered_hops.last_mut().unwrap().0.hop_use_fee_msat = 0;
 960                                 ordered_hops.last_mut().unwrap().0.cltv_expiry_delta = final_cltv;
 961
 962                                 let mut payment_path = PaymentPath {hops: ordered_hops};
 963
 964                                 // We could have possibly constructed a slightly inconsistent path: since we reduce
 965                                 // value being transferred along the way, we could have violated htlc_minimum_msat
 966                                 // on some channels we already passed (assuming dest->source direction). Here, we
 967                                 // recompute the fees again, so that if that's the case, we match the currently
 968                                 // underpaid htlc_minimum_msat with fees.
 969                                 payment_path.update_value_and_recompute_fees(cmp::min(value_contribution_msat, final_value_msat));
 970
 971                                 // Since a path allows to transfer as much value as
 972                                 // the smallest channel it has ("bottleneck"), we should recompute
 973                                 // the fees so sender HTLC don't overpay fees when traversing
 974                                 // larger channels than the bottleneck. This may happen because
 975                                 // when we were selecting those channels we were not aware how much value
 976                                 // this path will transfer, and the relative fee for them
 977                                 // might have been computed considering a larger value.
 978                                 // Remember that we used these channels so that we don't rely
 979                                 // on the same liquidity in future paths.
 980                                 let mut prevented_redundant_path_selection = false;
 981                                 for (payment_hop, _) in payment_path.hops.iter() {
 982                                         let channel_liquidity_available_msat = bookkeeped_channels_liquidity_available_msat.get_mut(&payment_hop.short_channel_id).unwrap();
 983                                         let mut spent_on_hop_msat = value_contribution_msat;
 984                                         let next_hops_fee_msat = payment_hop.next_hops_fee_msat;
 985                                         spent_on_hop_msat += next_hops_fee_msat;
 986                                         if spent_on_hop_msat == *channel_liquidity_available_msat {
 987                                                 // If this path used all of this channel's available liquidity, we know
 988                                                 // this path will not be selected again in the next loop iteration.
 989                                                 prevented_redundant_path_selection = true;
 990                                         }
 991                                         *channel_liquidity_available_msat -= spent_on_hop_msat;
 992                                 }
 993                                 if !prevented_redundant_path_selection {
 994                                         // If we weren't capped by hitting a liquidity limit on a channel in the path,
 995                                         // we'll probably end up picking the same path again on the next iteration.
 996                                         // Decrease the available liquidity of a hop in the middle of the path.
 997                                         let victim_liquidity = bookkeeped_channels_liquidity_available_msat.get_mut(
 998                                                 &payment_path.hops[(payment_path.hops.len() - 1) / 2].0.short_channel_id).unwrap();
 999                                         *victim_liquidity = 0;
1000                                 }
1001
1002                                 // Track the total amount all our collected paths allow to send so that we:
1003                                 // - know when to stop looking for more paths
1004                                 // - know which of the hops are useless considering how much more sats we need
1005                                 //   (contributes_sufficient_value)
1006                                 already_collected_value_msat += value_contribution_msat;
1007
1008                                 payment_paths.push(payment_path);
1009                                 found_new_path = true;
1010                                 break 'path_construction;
1011                         }
1012
1013                         // If we found a path back to the payee, we shouldn't try to process it again. This is
1014                         // the equivalent of the `elem.was_processed` check in
1015                         // add_entries_to_cheapest_to_target_node!() (see comment there for more info).
1016                         if pubkey == *payee { continue 'path_construction; }
1017
1018                         // Otherwise, since the current target node is not us,
1019                         // keep "unrolling" the payment graph from payee to payer by
1020                         // finding a way to reach the current target from the payer side.
1021                         match network.get_nodes().get(&pubkey) {
1022                                 None => {},
1023                                 Some(node) => {
1024                                         add_entries_to_cheapest_to_target_node!(node, &pubkey, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat);
1025                                 },
1026                         }
1027                 }
1028
1029                 if !allow_mpp {
1030                         // If we don't support MPP, no use trying to gather more value ever.
1031                         break 'paths_collection;
1032                 }
1033
1034                 // Step (3).
1035                 // Stop either when the recommended value is reached or if no new path was found in this
1036                 // iteration.
1037                 // In the latter case, making another path finding attempt won't help,
1038                 // because we deterministically terminated the search due to low liquidity.
1039                 if already_collected_value_msat >= recommended_value_msat || !found_new_path {
1040                         break 'paths_collection;
1041                 } else if found_new_path && already_collected_value_msat == final_value_msat && payment_paths.len() == 1 {
1042                         // Further, if this was our first walk of the graph, and we weren't limited by an
1043                         // htlc_minimum_msat, return immediately because this path should suffice. If we were
1044                         // limited by an htlc_minimum_msat value, find another path with a higher value,
1045                         // potentially allowing us to pay fees to meet the htlc_minimum on the new path while
1046                         // still keeping a lower total fee than this path.
1047                         if !hit_minimum_limit {
1048                                 break 'paths_collection;
1049                         }
1050                         path_value_msat = recommended_value_msat;
1051                 }
1052         }
1053
1054         // Step (4).
1055         if payment_paths.len() == 0 {
1056                 return Err(LightningError{err: "Failed to find a path to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1057         }
1058
1059         if already_collected_value_msat < final_value_msat {
1060                 return Err(LightningError{err: "Failed to find a sufficient route to the given destination".to_owned(), action: ErrorAction::IgnoreError});
1061         }
1062
1063         // Sort by total fees and take the best paths.
1064         payment_paths.sort_by_key(|path| path.get_total_fee_paid_msat());
1065         if payment_paths.len() > 50 {
1066                 payment_paths.truncate(50);
1067         }
1068
1069         // Draw multiple sufficient routes by randomly combining the selected paths.
1070         let mut drawn_routes = Vec::new();
1071         for i in 0..payment_paths.len() {
1072                 let mut cur_route = Vec::<PaymentPath>::new();
1073                 let mut aggregate_route_value_msat = 0;
1074
1075                 // Step (5).
1076                 // TODO: real random shuffle
1077                 // Currently just starts with i_th and goes up to i-1_th in a looped way.
1078                 let cur_payment_paths = [&payment_paths[i..], &payment_paths[..i]].concat();
1079
1080                 // Step (6).
1081                 for payment_path in cur_payment_paths {
1082                         cur_route.push(payment_path.clone());
1083                         aggregate_route_value_msat += payment_path.get_value_msat();
1084                         if aggregate_route_value_msat > final_value_msat {
1085                                 // Last path likely overpaid. Substract it from the most expensive
1086                                 // (in terms of proportional fee) path in this route and recompute fees.
1087                                 // This might be not the most economically efficient way, but fewer paths
1088                                 // also makes routing more reliable.
1089                                 let mut overpaid_value_msat = aggregate_route_value_msat - final_value_msat;
1090
1091                                 // First, drop some expensive low-value paths entirely if possible.
1092                                 // Sort by value so that we drop many really-low values first, since
1093                                 // fewer paths is better: the payment is less likely to fail.
1094                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1095                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1096                                 cur_route.sort_by_key(|path| path.get_value_msat());
1097                                 // We should make sure that at least 1 path left.
1098                                 let mut paths_left = cur_route.len();
1099                                 cur_route.retain(|path| {
1100                                         if paths_left == 1 {
1101                                                 return true
1102                                         }
1103                                         let mut keep = true;
1104                                         let path_value_msat = path.get_value_msat();
1105                                         if path_value_msat <= overpaid_value_msat {
1106                                                 keep = false;
1107                                                 overpaid_value_msat -= path_value_msat;
1108                                                 paths_left -= 1;
1109                                         }
1110                                         keep
1111                                 });
1112
1113                                 if overpaid_value_msat == 0 {
1114                                         break;
1115                                 }
1116
1117                                 assert!(cur_route.len() > 0);
1118
1119                                 // Step (7).
1120                                 // Now, substract the overpaid value from the most-expensive path.
1121                                 // TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
1122                                 // so that the sender pays less fees overall. And also htlc_minimum_msat.
1123                                 cur_route.sort_by_key(|path| { path.hops.iter().map(|hop| hop.0.channel_fees.proportional_millionths as u64).sum::<u64>() });
1124                                 let expensive_payment_path = cur_route.first_mut().unwrap();
1125                                 // We already dropped all the small channels above, meaning all the
1126                                 // remaining channels are larger than remaining overpaid_value_msat.
1127                                 // Thus, this can't be negative.
1128                                 let expensive_path_new_value_msat = expensive_payment_path.get_value_msat() - overpaid_value_msat;
1129                                 expensive_payment_path.update_value_and_recompute_fees(expensive_path_new_value_msat);
1130                                 break;
1131                         }
1132                 }
1133                 drawn_routes.push(cur_route);
1134         }
1135
1136         // Step (8).
1137         // Select the best route by lowest total fee.
1138         drawn_routes.sort_by_key(|paths| paths.iter().map(|path| path.get_total_fee_paid_msat()).sum::<u64>());
1139         let mut selected_paths = Vec::<Vec<RouteHop>>::new();
1140         for payment_path in drawn_routes.first().unwrap() {
1141                 selected_paths.push(payment_path.hops.iter().map(|(payment_hop, node_features)| {
1142                         RouteHop {
1143                                 pubkey: payment_hop.pubkey,
1144                                 node_features: node_features.clone(),
1145                                 short_channel_id: payment_hop.short_channel_id,
1146                                 channel_features: payment_hop.channel_features.clone(),
1147                                 fee_msat: payment_hop.fee_msat,
1148                                 cltv_expiry_delta: payment_hop.cltv_expiry_delta,
1149                         }
1150                 }).collect());
1151         }
1152
1153         if let Some(features) = &payee_features {
1154                 for path in selected_paths.iter_mut() {
1155                         path.last_mut().unwrap().node_features = features.to_context();
1156                 }
1157         }
1158
1159         let route = Route { paths: selected_paths };
1160         log_trace!(logger, "Got route: {}", log_route!(route));
1161         Ok(route)
1162 }
1163
1164 #[cfg(test)]
1165 mod tests {
1166         use routing::router::{get_route, RouteHint, RoutingFees};
1167         use routing::network_graph::{NetworkGraph, NetGraphMsgHandler};
1168         use ln::features::{ChannelFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
1169         use ln::msgs::{ErrorAction, LightningError, OptionalField, UnsignedChannelAnnouncement, ChannelAnnouncement, RoutingMessageHandler,
1170            NodeAnnouncement, UnsignedNodeAnnouncement, ChannelUpdate, UnsignedChannelUpdate};
1171         use ln::channelmanager;
1172         use util::test_utils;
1173         use util::ser::Writeable;
1174
1175         use bitcoin::hashes::sha256d::Hash as Sha256dHash;
1176         use bitcoin::hashes::Hash;
1177         use bitcoin::network::constants::Network;
1178         use bitcoin::blockdata::constants::genesis_block;
1179         use bitcoin::blockdata::script::Builder;
1180         use bitcoin::blockdata::opcodes;
1181         use bitcoin::blockdata::transaction::TxOut;
1182
1183         use hex;
1184
1185         use bitcoin::secp256k1::key::{PublicKey,SecretKey};
1186         use bitcoin::secp256k1::{Secp256k1, All};
1187
1188         use std::sync::Arc;
1189
1190         // Using the same keys for LN and BTC ids
1191         fn add_channel(net_graph_msg_handler: &NetGraphMsgHandler<Arc<test_utils::TestChainSource>, Arc<test_utils::TestLogger>>, secp_ctx: &Secp256k1<All>, node_1_privkey: &SecretKey,
1192            node_2_privkey: &SecretKey, features: ChannelFeatures, short_channel_id: u64) {
1193                 let node_id_1 = PublicKey::from_secret_key(&secp_ctx, node_1_privkey);
1194                 let node_id_2 = PublicKey::from_secret_key(&secp_ctx, node_2_privkey);
1195
1196                 let unsigned_announcement = UnsignedChannelAnnouncement {
1197                         features,
1198                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1199                         short_channel_id,
1200                         node_id_1,
1201                         node_id_2,
1202                         bitcoin_key_1: node_id_1,
1203                         bitcoin_key_2: node_id_2,
1204                         excess_data: Vec::new(),
1205                 };
1206
1207                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1208                 let valid_announcement = ChannelAnnouncement {
1209                         node_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1210                         node_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1211                         bitcoin_signature_1: secp_ctx.sign(&msghash, node_1_privkey),
1212                         bitcoin_signature_2: secp_ctx.sign(&msghash, node_2_privkey),
1213                         contents: unsigned_announcement.clone(),
1214                 };
1215                 match net_graph_msg_handler.handle_channel_announcement(&valid_announcement) {
1216                         Ok(res) => assert!(res),
1217                         _ => panic!()
1218                 };
1219         }
1220
1221         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) {
1222                 let msghash = hash_to_message!(&Sha256dHash::hash(&update.encode()[..])[..]);
1223                 let valid_channel_update = ChannelUpdate {
1224                         signature: secp_ctx.sign(&msghash, node_privkey),
1225                         contents: update.clone()
1226                 };
1227
1228                 match net_graph_msg_handler.handle_channel_update(&valid_channel_update) {
1229                         Ok(res) => assert!(res),
1230                         Err(_) => panic!()
1231                 };
1232         }
1233
1234         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,
1235            features: NodeFeatures, timestamp: u32) {
1236                 let node_id = PublicKey::from_secret_key(&secp_ctx, node_privkey);
1237                 let unsigned_announcement = UnsignedNodeAnnouncement {
1238                         features,
1239                         timestamp,
1240                         node_id,
1241                         rgb: [0; 3],
1242                         alias: [0; 32],
1243                         addresses: Vec::new(),
1244                         excess_address_data: Vec::new(),
1245                         excess_data: Vec::new(),
1246                 };
1247                 let msghash = hash_to_message!(&Sha256dHash::hash(&unsigned_announcement.encode()[..])[..]);
1248                 let valid_announcement = NodeAnnouncement {
1249                         signature: secp_ctx.sign(&msghash, node_privkey),
1250                         contents: unsigned_announcement.clone()
1251                 };
1252
1253                 match net_graph_msg_handler.handle_node_announcement(&valid_announcement) {
1254                         Ok(_) => (),
1255                         Err(_) => panic!()
1256                 };
1257         }
1258
1259         fn get_nodes(secp_ctx: &Secp256k1<All>) -> (SecretKey, PublicKey, Vec<SecretKey>, Vec<PublicKey>) {
1260                 let privkeys: Vec<SecretKey> = (2..10).map(|i| {
1261                         SecretKey::from_slice(&hex::decode(format!("{:02}", i).repeat(32)).unwrap()[..]).unwrap()
1262                 }).collect();
1263
1264                 let pubkeys = privkeys.iter().map(|secret| PublicKey::from_secret_key(&secp_ctx, secret)).collect();
1265
1266                 let our_privkey = SecretKey::from_slice(&hex::decode("01".repeat(32)).unwrap()[..]).unwrap();
1267                 let our_id = PublicKey::from_secret_key(&secp_ctx, &our_privkey);
1268
1269                 (our_privkey, our_id, privkeys, pubkeys)
1270         }
1271
1272         fn id_to_feature_flags(id: u8) -> Vec<u8> {
1273                 // Set the feature flags to the id'th odd (ie non-required) feature bit so that we can
1274                 // test for it later.
1275                 let idx = (id - 1) * 2 + 1;
1276                 if idx > 8*3 {
1277                         vec![1 << (idx - 8*3), 0, 0, 0]
1278                 } else if idx > 8*2 {
1279                         vec![1 << (idx - 8*2), 0, 0]
1280                 } else if idx > 8*1 {
1281                         vec![1 << (idx - 8*1), 0]
1282                 } else {
1283                         vec![1 << idx]
1284                 }
1285         }
1286
1287         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>) {
1288                 let secp_ctx = Secp256k1::new();
1289                 let logger = Arc::new(test_utils::TestLogger::new());
1290                 let chain_monitor = Arc::new(test_utils::TestChainSource::new(Network::Testnet));
1291                 let net_graph_msg_handler = NetGraphMsgHandler::new(genesis_block(Network::Testnet).header.block_hash(), None, Arc::clone(&logger));
1292                 // Build network from our_id to node7:
1293                 //
1294                 //        -1(1)2-  node0  -1(3)2-
1295                 //       /                       \
1296                 // our_id -1(12)2- node7 -1(13)2--- node2
1297                 //       \                       /
1298                 //        -1(2)2-  node1  -1(4)2-
1299                 //
1300                 //
1301                 // chan1  1-to-2: disabled
1302                 // chan1  2-to-1: enabled, 0 fee
1303                 //
1304                 // chan2  1-to-2: enabled, ignored fee
1305                 // chan2  2-to-1: enabled, 0 fee
1306                 //
1307                 // chan3  1-to-2: enabled, 0 fee
1308                 // chan3  2-to-1: enabled, 100 msat fee
1309                 //
1310                 // chan4  1-to-2: enabled, 100% fee
1311                 // chan4  2-to-1: enabled, 0 fee
1312                 //
1313                 // chan12 1-to-2: enabled, ignored fee
1314                 // chan12 2-to-1: enabled, 0 fee
1315                 //
1316                 // chan13 1-to-2: enabled, 200% fee
1317                 // chan13 2-to-1: enabled, 0 fee
1318                 //
1319                 //
1320                 //       -1(5)2- node3 -1(8)2--
1321                 //       |         2          |
1322                 //       |       (11)         |
1323                 //      /          1           \
1324                 // node2--1(6)2- node4 -1(9)2--- node6 (not in global route map)
1325                 //      \                      /
1326                 //       -1(7)2- node5 -1(10)2-
1327                 //
1328                 // chan5  1-to-2: enabled, 100 msat fee
1329                 // chan5  2-to-1: enabled, 0 fee
1330                 //
1331                 // chan6  1-to-2: enabled, 0 fee
1332                 // chan6  2-to-1: enabled, 0 fee
1333                 //
1334                 // chan7  1-to-2: enabled, 100% fee
1335                 // chan7  2-to-1: enabled, 0 fee
1336                 //
1337                 // chan8  1-to-2: enabled, variable fee (0 then 1000 msat)
1338                 // chan8  2-to-1: enabled, 0 fee
1339                 //
1340                 // chan9  1-to-2: enabled, 1001 msat fee
1341                 // chan9  2-to-1: enabled, 0 fee
1342                 //
1343                 // chan10 1-to-2: enabled, 0 fee
1344                 // chan10 2-to-1: enabled, 0 fee
1345                 //
1346                 // chan11 1-to-2: enabled, 0 fee
1347                 // chan11 2-to-1: enabled, 0 fee
1348
1349                 let (our_privkey, _, privkeys, _) = get_nodes(&secp_ctx);
1350
1351                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[0], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
1352                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1353                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1354                         short_channel_id: 1,
1355                         timestamp: 1,
1356                         flags: 1,
1357                         cltv_expiry_delta: 0,
1358                         htlc_minimum_msat: 0,
1359                         htlc_maximum_msat: OptionalField::Absent,
1360                         fee_base_msat: 0,
1361                         fee_proportional_millionths: 0,
1362                         excess_data: Vec::new()
1363                 });
1364
1365                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
1366
1367                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
1368                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1369                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1370                         short_channel_id: 2,
1371                         timestamp: 1,
1372                         flags: 0,
1373                         cltv_expiry_delta: u16::max_value(),
1374                         htlc_minimum_msat: 0,
1375                         htlc_maximum_msat: OptionalField::Absent,
1376                         fee_base_msat: u32::max_value(),
1377                         fee_proportional_millionths: u32::max_value(),
1378                         excess_data: Vec::new()
1379                 });
1380                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1381                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1382                         short_channel_id: 2,
1383                         timestamp: 1,
1384                         flags: 1,
1385                         cltv_expiry_delta: 0,
1386                         htlc_minimum_msat: 0,
1387                         htlc_maximum_msat: OptionalField::Absent,
1388                         fee_base_msat: 0,
1389                         fee_proportional_millionths: 0,
1390                         excess_data: Vec::new()
1391                 });
1392
1393                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
1394
1395                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[7], ChannelFeatures::from_le_bytes(id_to_feature_flags(12)), 12);
1396                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1397                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1398                         short_channel_id: 12,
1399                         timestamp: 1,
1400                         flags: 0,
1401                         cltv_expiry_delta: u16::max_value(),
1402                         htlc_minimum_msat: 0,
1403                         htlc_maximum_msat: OptionalField::Absent,
1404                         fee_base_msat: u32::max_value(),
1405                         fee_proportional_millionths: u32::max_value(),
1406                         excess_data: Vec::new()
1407                 });
1408                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1409                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1410                         short_channel_id: 12,
1411                         timestamp: 1,
1412                         flags: 1,
1413                         cltv_expiry_delta: 0,
1414                         htlc_minimum_msat: 0,
1415                         htlc_maximum_msat: OptionalField::Absent,
1416                         fee_base_msat: 0,
1417                         fee_proportional_millionths: 0,
1418                         excess_data: Vec::new()
1419                 });
1420
1421                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], NodeFeatures::from_le_bytes(id_to_feature_flags(8)), 0);
1422
1423                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
1424                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1425                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1426                         short_channel_id: 3,
1427                         timestamp: 1,
1428                         flags: 0,
1429                         cltv_expiry_delta: (3 << 8) | 1,
1430                         htlc_minimum_msat: 0,
1431                         htlc_maximum_msat: OptionalField::Absent,
1432                         fee_base_msat: 0,
1433                         fee_proportional_millionths: 0,
1434                         excess_data: Vec::new()
1435                 });
1436                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1437                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1438                         short_channel_id: 3,
1439                         timestamp: 1,
1440                         flags: 1,
1441                         cltv_expiry_delta: (3 << 8) | 2,
1442                         htlc_minimum_msat: 0,
1443                         htlc_maximum_msat: OptionalField::Absent,
1444                         fee_base_msat: 100,
1445                         fee_proportional_millionths: 0,
1446                         excess_data: Vec::new()
1447                 });
1448
1449                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
1450                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1451                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1452                         short_channel_id: 4,
1453                         timestamp: 1,
1454                         flags: 0,
1455                         cltv_expiry_delta: (4 << 8) | 1,
1456                         htlc_minimum_msat: 0,
1457                         htlc_maximum_msat: OptionalField::Absent,
1458                         fee_base_msat: 0,
1459                         fee_proportional_millionths: 1000000,
1460                         excess_data: Vec::new()
1461                 });
1462                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1463                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1464                         short_channel_id: 4,
1465                         timestamp: 1,
1466                         flags: 1,
1467                         cltv_expiry_delta: (4 << 8) | 2,
1468                         htlc_minimum_msat: 0,
1469                         htlc_maximum_msat: OptionalField::Absent,
1470                         fee_base_msat: 0,
1471                         fee_proportional_millionths: 0,
1472                         excess_data: Vec::new()
1473                 });
1474
1475                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(13)), 13);
1476                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1477                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1478                         short_channel_id: 13,
1479                         timestamp: 1,
1480                         flags: 0,
1481                         cltv_expiry_delta: (13 << 8) | 1,
1482                         htlc_minimum_msat: 0,
1483                         htlc_maximum_msat: OptionalField::Absent,
1484                         fee_base_msat: 0,
1485                         fee_proportional_millionths: 2000000,
1486                         excess_data: Vec::new()
1487                 });
1488                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1489                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1490                         short_channel_id: 13,
1491                         timestamp: 1,
1492                         flags: 1,
1493                         cltv_expiry_delta: (13 << 8) | 2,
1494                         htlc_minimum_msat: 0,
1495                         htlc_maximum_msat: OptionalField::Absent,
1496                         fee_base_msat: 0,
1497                         fee_proportional_millionths: 0,
1498                         excess_data: Vec::new()
1499                 });
1500
1501                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
1502
1503                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
1504                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1505                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1506                         short_channel_id: 6,
1507                         timestamp: 1,
1508                         flags: 0,
1509                         cltv_expiry_delta: (6 << 8) | 1,
1510                         htlc_minimum_msat: 0,
1511                         htlc_maximum_msat: OptionalField::Absent,
1512                         fee_base_msat: 0,
1513                         fee_proportional_millionths: 0,
1514                         excess_data: Vec::new()
1515                 });
1516                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1517                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1518                         short_channel_id: 6,
1519                         timestamp: 1,
1520                         flags: 1,
1521                         cltv_expiry_delta: (6 << 8) | 2,
1522                         htlc_minimum_msat: 0,
1523                         htlc_maximum_msat: OptionalField::Absent,
1524                         fee_base_msat: 0,
1525                         fee_proportional_millionths: 0,
1526                         excess_data: Vec::new(),
1527                 });
1528
1529                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(11)), 11);
1530                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
1531                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1532                         short_channel_id: 11,
1533                         timestamp: 1,
1534                         flags: 0,
1535                         cltv_expiry_delta: (11 << 8) | 1,
1536                         htlc_minimum_msat: 0,
1537                         htlc_maximum_msat: OptionalField::Absent,
1538                         fee_base_msat: 0,
1539                         fee_proportional_millionths: 0,
1540                         excess_data: Vec::new()
1541                 });
1542                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
1543                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1544                         short_channel_id: 11,
1545                         timestamp: 1,
1546                         flags: 1,
1547                         cltv_expiry_delta: (11 << 8) | 2,
1548                         htlc_minimum_msat: 0,
1549                         htlc_maximum_msat: OptionalField::Absent,
1550                         fee_base_msat: 0,
1551                         fee_proportional_millionths: 0,
1552                         excess_data: Vec::new()
1553                 });
1554
1555                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(5)), 0);
1556
1557                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
1558
1559                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[5], ChannelFeatures::from_le_bytes(id_to_feature_flags(7)), 7);
1560                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1561                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1562                         short_channel_id: 7,
1563                         timestamp: 1,
1564                         flags: 0,
1565                         cltv_expiry_delta: (7 << 8) | 1,
1566                         htlc_minimum_msat: 0,
1567                         htlc_maximum_msat: OptionalField::Absent,
1568                         fee_base_msat: 0,
1569                         fee_proportional_millionths: 1000000,
1570                         excess_data: Vec::new()
1571                 });
1572                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[5], UnsignedChannelUpdate {
1573                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1574                         short_channel_id: 7,
1575                         timestamp: 1,
1576                         flags: 1,
1577                         cltv_expiry_delta: (7 << 8) | 2,
1578                         htlc_minimum_msat: 0,
1579                         htlc_maximum_msat: OptionalField::Absent,
1580                         fee_base_msat: 0,
1581                         fee_proportional_millionths: 0,
1582                         excess_data: Vec::new()
1583                 });
1584
1585                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[5], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
1586
1587                 (secp_ctx, net_graph_msg_handler, chain_monitor, logger)
1588         }
1589
1590         #[test]
1591         fn simple_route_test() {
1592                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1593                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1594
1595                 // Simple route to 2 via 1
1596
1597                 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)) {
1598                         assert_eq!(err, "Cannot send a payment of 0 msat");
1599                 } else { panic!(); }
1600
1601                 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();
1602                 assert_eq!(route.paths[0].len(), 2);
1603
1604                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
1605                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1606                 assert_eq!(route.paths[0][0].fee_msat, 100);
1607                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
1608                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
1609                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
1610
1611                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1612                 assert_eq!(route.paths[0][1].short_channel_id, 4);
1613                 assert_eq!(route.paths[0][1].fee_msat, 100);
1614                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1615                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1616                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
1617         }
1618
1619         #[test]
1620         fn invalid_first_hop_test() {
1621                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1622                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
1623
1624                 // Simple route to 2 via 1
1625
1626                 let our_chans = vec![channelmanager::ChannelDetails {
1627                         channel_id: [0; 32],
1628                         short_channel_id: Some(2),
1629                         remote_network_id: our_id,
1630                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1631                         channel_value_satoshis: 100000,
1632                         user_id: 0,
1633                         outbound_capacity_msat: 100000,
1634                         inbound_capacity_msat: 100000,
1635                         is_live: true,
1636                         counterparty_forwarding_info: None,
1637                 }];
1638
1639                 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)) {
1640                         assert_eq!(err, "First hop cannot have our_node_id as a destination.");
1641                 } else { panic!(); }
1642
1643                 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();
1644                 assert_eq!(route.paths[0].len(), 2);
1645         }
1646
1647         #[test]
1648         fn htlc_minimum_test() {
1649                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1650                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1651
1652                 // Simple route to 2 via 1
1653
1654                 // Disable other paths
1655                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1656                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1657                         short_channel_id: 12,
1658                         timestamp: 2,
1659                         flags: 2, // to disable
1660                         cltv_expiry_delta: 0,
1661                         htlc_minimum_msat: 0,
1662                         htlc_maximum_msat: OptionalField::Absent,
1663                         fee_base_msat: 0,
1664                         fee_proportional_millionths: 0,
1665                         excess_data: Vec::new()
1666                 });
1667                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
1668                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1669                         short_channel_id: 3,
1670                         timestamp: 2,
1671                         flags: 2, // to disable
1672                         cltv_expiry_delta: 0,
1673                         htlc_minimum_msat: 0,
1674                         htlc_maximum_msat: OptionalField::Absent,
1675                         fee_base_msat: 0,
1676                         fee_proportional_millionths: 0,
1677                         excess_data: Vec::new()
1678                 });
1679                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1680                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1681                         short_channel_id: 13,
1682                         timestamp: 2,
1683                         flags: 2, // to disable
1684                         cltv_expiry_delta: 0,
1685                         htlc_minimum_msat: 0,
1686                         htlc_maximum_msat: OptionalField::Absent,
1687                         fee_base_msat: 0,
1688                         fee_proportional_millionths: 0,
1689                         excess_data: Vec::new()
1690                 });
1691                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1692                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1693                         short_channel_id: 6,
1694                         timestamp: 2,
1695                         flags: 2, // to disable
1696                         cltv_expiry_delta: 0,
1697                         htlc_minimum_msat: 0,
1698                         htlc_maximum_msat: OptionalField::Absent,
1699                         fee_base_msat: 0,
1700                         fee_proportional_millionths: 0,
1701                         excess_data: Vec::new()
1702                 });
1703                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
1704                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1705                         short_channel_id: 7,
1706                         timestamp: 2,
1707                         flags: 2, // to disable
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
1716                 // Check against amount_to_transfer_over_msat.
1717                 // Set minimal HTLC of 200_000_000 msat.
1718                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1719                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1720                         short_channel_id: 2,
1721                         timestamp: 3,
1722                         flags: 0,
1723                         cltv_expiry_delta: 0,
1724                         htlc_minimum_msat: 200_000_000,
1725                         htlc_maximum_msat: OptionalField::Absent,
1726                         fee_base_msat: 0,
1727                         fee_proportional_millionths: 0,
1728                         excess_data: Vec::new()
1729                 });
1730
1731                 // Second hop only allows to forward 199_999_999 at most, thus not allowing the first hop to
1732                 // be used.
1733                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1734                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1735                         short_channel_id: 4,
1736                         timestamp: 3,
1737                         flags: 0,
1738                         cltv_expiry_delta: 0,
1739                         htlc_minimum_msat: 0,
1740                         htlc_maximum_msat: OptionalField::Present(199_999_999),
1741                         fee_base_msat: 0,
1742                         fee_proportional_millionths: 0,
1743                         excess_data: Vec::new()
1744                 });
1745
1746                 // Not possible to send 199_999_999, because the minimum on channel=2 is 200_000_000.
1747                 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)) {
1748                         assert_eq!(err, "Failed to find a path to the given destination");
1749                 } else { panic!(); }
1750
1751                 // Lift the restriction on the first hop.
1752                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1753                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1754                         short_channel_id: 2,
1755                         timestamp: 4,
1756                         flags: 0,
1757                         cltv_expiry_delta: 0,
1758                         htlc_minimum_msat: 0,
1759                         htlc_maximum_msat: OptionalField::Absent,
1760                         fee_base_msat: 0,
1761                         fee_proportional_millionths: 0,
1762                         excess_data: Vec::new()
1763                 });
1764
1765                 // A payment above the minimum should pass
1766                 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();
1767                 assert_eq!(route.paths[0].len(), 2);
1768         }
1769
1770         #[test]
1771         fn htlc_minimum_overpay_test() {
1772                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1773                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1774
1775                 // A route to node#2 via two paths.
1776                 // One path allows transferring 35-40 sats, another one also allows 35-40 sats.
1777                 // Thus, they can't send 60 without overpaying.
1778                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1779                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1780                         short_channel_id: 2,
1781                         timestamp: 2,
1782                         flags: 0,
1783                         cltv_expiry_delta: 0,
1784                         htlc_minimum_msat: 35_000,
1785                         htlc_maximum_msat: OptionalField::Present(40_000),
1786                         fee_base_msat: 0,
1787                         fee_proportional_millionths: 0,
1788                         excess_data: Vec::new()
1789                 });
1790                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1791                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1792                         short_channel_id: 12,
1793                         timestamp: 3,
1794                         flags: 0,
1795                         cltv_expiry_delta: 0,
1796                         htlc_minimum_msat: 35_000,
1797                         htlc_maximum_msat: OptionalField::Present(40_000),
1798                         fee_base_msat: 0,
1799                         fee_proportional_millionths: 0,
1800                         excess_data: Vec::new()
1801                 });
1802
1803                 // Make 0 fee.
1804                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
1805                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1806                         short_channel_id: 13,
1807                         timestamp: 2,
1808                         flags: 0,
1809                         cltv_expiry_delta: 0,
1810                         htlc_minimum_msat: 0,
1811                         htlc_maximum_msat: OptionalField::Absent,
1812                         fee_base_msat: 0,
1813                         fee_proportional_millionths: 0,
1814                         excess_data: Vec::new()
1815                 });
1816                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1817                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1818                         short_channel_id: 4,
1819                         timestamp: 2,
1820                         flags: 0,
1821                         cltv_expiry_delta: 0,
1822                         htlc_minimum_msat: 0,
1823                         htlc_maximum_msat: OptionalField::Absent,
1824                         fee_base_msat: 0,
1825                         fee_proportional_millionths: 0,
1826                         excess_data: Vec::new()
1827                 });
1828
1829                 // Disable other paths
1830                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1831                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1832                         short_channel_id: 1,
1833                         timestamp: 3,
1834                         flags: 2, // to disable
1835                         cltv_expiry_delta: 0,
1836                         htlc_minimum_msat: 0,
1837                         htlc_maximum_msat: OptionalField::Absent,
1838                         fee_base_msat: 0,
1839                         fee_proportional_millionths: 0,
1840                         excess_data: Vec::new()
1841                 });
1842
1843                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1844                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)).unwrap();
1845                 // Overpay fees to hit htlc_minimum_msat.
1846                 let overpaid_fees = route.paths[0][0].fee_msat + route.paths[1][0].fee_msat;
1847                 // TODO: this could be better balanced to overpay 10k and not 15k.
1848                 assert_eq!(overpaid_fees, 15_000);
1849
1850                 // Now, test that if there are 2 paths, a "cheaper" by fee path wouldn't be prioritized
1851                 // while taking even more fee to match htlc_minimum_msat.
1852                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1853                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1854                         short_channel_id: 12,
1855                         timestamp: 4,
1856                         flags: 0,
1857                         cltv_expiry_delta: 0,
1858                         htlc_minimum_msat: 65_000,
1859                         htlc_maximum_msat: OptionalField::Present(80_000),
1860                         fee_base_msat: 0,
1861                         fee_proportional_millionths: 0,
1862                         excess_data: Vec::new()
1863                 });
1864                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1865                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1866                         short_channel_id: 2,
1867                         timestamp: 3,
1868                         flags: 0,
1869                         cltv_expiry_delta: 0,
1870                         htlc_minimum_msat: 0,
1871                         htlc_maximum_msat: OptionalField::Absent,
1872                         fee_base_msat: 0,
1873                         fee_proportional_millionths: 0,
1874                         excess_data: Vec::new()
1875                 });
1876                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1877                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1878                         short_channel_id: 4,
1879                         timestamp: 4,
1880                         flags: 0,
1881                         cltv_expiry_delta: 0,
1882                         htlc_minimum_msat: 0,
1883                         htlc_maximum_msat: OptionalField::Absent,
1884                         fee_base_msat: 0,
1885                         fee_proportional_millionths: 100_000,
1886                         excess_data: Vec::new()
1887                 });
1888
1889                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1890                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)).unwrap();
1891                 // Fine to overpay for htlc_minimum_msat if it allows us to save fee.
1892                 assert_eq!(route.paths.len(), 1);
1893                 assert_eq!(route.paths[0][0].short_channel_id, 12);
1894                 let fees = route.paths[0][0].fee_msat;
1895                 assert_eq!(fees, 5_000);
1896
1897                 let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
1898                         Some(InvoiceFeatures::known()), None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
1899                 // Not fine to overpay for htlc_minimum_msat if it requires paying more than fee on
1900                 // the other channel.
1901                 assert_eq!(route.paths.len(), 1);
1902                 assert_eq!(route.paths[0][0].short_channel_id, 2);
1903                 let fees = route.paths[0][0].fee_msat;
1904                 assert_eq!(fees, 5_000);
1905         }
1906
1907         #[test]
1908         fn disable_channels_test() {
1909                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1910                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1911
1912                 // // Disable channels 4 and 12 by flags=2
1913                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
1914                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1915                         short_channel_id: 4,
1916                         timestamp: 2,
1917                         flags: 2, // to disable
1918                         cltv_expiry_delta: 0,
1919                         htlc_minimum_msat: 0,
1920                         htlc_maximum_msat: OptionalField::Absent,
1921                         fee_base_msat: 0,
1922                         fee_proportional_millionths: 0,
1923                         excess_data: Vec::new()
1924                 });
1925                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
1926                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
1927                         short_channel_id: 12,
1928                         timestamp: 2,
1929                         flags: 2, // to disable
1930                         cltv_expiry_delta: 0,
1931                         htlc_minimum_msat: 0,
1932                         htlc_maximum_msat: OptionalField::Absent,
1933                         fee_base_msat: 0,
1934                         fee_proportional_millionths: 0,
1935                         excess_data: Vec::new()
1936                 });
1937
1938                 // If all the channels require some features we don't understand, route should fail
1939                 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)) {
1940                         assert_eq!(err, "Failed to find a path to the given destination");
1941                 } else { panic!(); }
1942
1943                 // If we specify a channel to node7, that overrides our local channel view and that gets used
1944                 let our_chans = vec![channelmanager::ChannelDetails {
1945                         channel_id: [0; 32],
1946                         short_channel_id: Some(42),
1947                         remote_network_id: nodes[7].clone(),
1948                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1949                         channel_value_satoshis: 0,
1950                         user_id: 0,
1951                         outbound_capacity_msat: 250_000_000,
1952                         inbound_capacity_msat: 0,
1953                         is_live: true,
1954                         counterparty_forwarding_info: None,
1955                 }];
1956                 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();
1957                 assert_eq!(route.paths[0].len(), 2);
1958
1959                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
1960                 assert_eq!(route.paths[0][0].short_channel_id, 42);
1961                 assert_eq!(route.paths[0][0].fee_msat, 200);
1962                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
1963                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
1964                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
1965
1966                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
1967                 assert_eq!(route.paths[0][1].short_channel_id, 13);
1968                 assert_eq!(route.paths[0][1].fee_msat, 100);
1969                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
1970                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
1971                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
1972         }
1973
1974         #[test]
1975         fn disable_node_test() {
1976                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
1977                 let (_, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
1978
1979                 // Disable nodes 1, 2, and 8 by requiring unknown feature bits
1980                 let mut unknown_features = NodeFeatures::known();
1981                 unknown_features.set_required_unknown_bits();
1982                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[0], unknown_features.clone(), 1);
1983                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], unknown_features.clone(), 1);
1984                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[7], unknown_features.clone(), 1);
1985
1986                 // If all nodes require some features we don't understand, route should fail
1987                 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)) {
1988                         assert_eq!(err, "Failed to find a path to the given destination");
1989                 } else { panic!(); }
1990
1991                 // If we specify a channel to node7, that overrides our local channel view and that gets used
1992                 let our_chans = vec![channelmanager::ChannelDetails {
1993                         channel_id: [0; 32],
1994                         short_channel_id: Some(42),
1995                         remote_network_id: nodes[7].clone(),
1996                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
1997                         channel_value_satoshis: 0,
1998                         user_id: 0,
1999                         outbound_capacity_msat: 250_000_000,
2000                         inbound_capacity_msat: 0,
2001                         is_live: true,
2002                         counterparty_forwarding_info: None,
2003                 }];
2004                 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();
2005                 assert_eq!(route.paths[0].len(), 2);
2006
2007                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2008                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2009                 assert_eq!(route.paths[0][0].fee_msat, 200);
2010                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2011                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]); // it should also override our view of their features
2012                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2013
2014                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2015                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2016                 assert_eq!(route.paths[0][1].fee_msat, 100);
2017                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2018                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2019                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2020
2021                 // Note that we don't test disabling node 3 and failing to route to it, as we (somewhat
2022                 // naively) assume that the user checked the feature bits on the invoice, which override
2023                 // the node_announcement.
2024         }
2025
2026         #[test]
2027         fn our_chans_test() {
2028                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2029                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2030
2031                 // Route to 1 via 2 and 3 because our channel to 1 is disabled
2032                 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();
2033                 assert_eq!(route.paths[0].len(), 3);
2034
2035                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2036                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2037                 assert_eq!(route.paths[0][0].fee_msat, 200);
2038                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2039                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2040                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2041
2042                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2043                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2044                 assert_eq!(route.paths[0][1].fee_msat, 100);
2045                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (3 << 8) | 2);
2046                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2047                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2048
2049                 assert_eq!(route.paths[0][2].pubkey, nodes[0]);
2050                 assert_eq!(route.paths[0][2].short_channel_id, 3);
2051                 assert_eq!(route.paths[0][2].fee_msat, 100);
2052                 assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
2053                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(1));
2054                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(3));
2055
2056                 // If we specify a channel to node7, that overrides our local channel view and that gets used
2057                 let our_chans = vec![channelmanager::ChannelDetails {
2058                         channel_id: [0; 32],
2059                         short_channel_id: Some(42),
2060                         remote_network_id: nodes[7].clone(),
2061                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2062                         channel_value_satoshis: 0,
2063                         user_id: 0,
2064                         outbound_capacity_msat: 250_000_000,
2065                         inbound_capacity_msat: 0,
2066                         is_live: true,
2067                         counterparty_forwarding_info: None,
2068                 }];
2069                 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();
2070                 assert_eq!(route.paths[0].len(), 2);
2071
2072                 assert_eq!(route.paths[0][0].pubkey, nodes[7]);
2073                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2074                 assert_eq!(route.paths[0][0].fee_msat, 200);
2075                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
2076                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2077                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2078
2079                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2080                 assert_eq!(route.paths[0][1].short_channel_id, 13);
2081                 assert_eq!(route.paths[0][1].fee_msat, 100);
2082                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2083                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2084                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
2085         }
2086
2087         fn last_hops(nodes: &Vec<PublicKey>) -> Vec<RouteHint> {
2088                 let zero_fees = RoutingFees {
2089                         base_msat: 0,
2090                         proportional_millionths: 0,
2091                 };
2092                 vec!(RouteHint {
2093                         src_node_id: nodes[3].clone(),
2094                         short_channel_id: 8,
2095                         fees: zero_fees,
2096                         cltv_expiry_delta: (8 << 8) | 1,
2097                         htlc_minimum_msat: None,
2098                         htlc_maximum_msat: None,
2099                 }, RouteHint {
2100                         src_node_id: nodes[4].clone(),
2101                         short_channel_id: 9,
2102                         fees: RoutingFees {
2103                                 base_msat: 1001,
2104                                 proportional_millionths: 0,
2105                         },
2106                         cltv_expiry_delta: (9 << 8) | 1,
2107                         htlc_minimum_msat: None,
2108                         htlc_maximum_msat: None,
2109                 }, RouteHint {
2110                         src_node_id: nodes[5].clone(),
2111                         short_channel_id: 10,
2112                         fees: zero_fees,
2113                         cltv_expiry_delta: (10 << 8) | 1,
2114                         htlc_minimum_msat: None,
2115                         htlc_maximum_msat: None,
2116                 })
2117         }
2118
2119         #[test]
2120         fn last_hops_test() {
2121                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2122                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2123
2124                 // Simple test across 2, 3, 5, and 4 via a last_hop channel
2125
2126                 // First check that lst hop can't have its source as the payee.
2127                 let invalid_last_hop = RouteHint {
2128                         src_node_id: nodes[6],
2129                         short_channel_id: 8,
2130                         fees: RoutingFees {
2131                                 base_msat: 1000,
2132                                 proportional_millionths: 0,
2133                         },
2134                         cltv_expiry_delta: (8 << 8) | 1,
2135                         htlc_minimum_msat: None,
2136                         htlc_maximum_msat: None,
2137                 };
2138
2139                 let mut invalid_last_hops = last_hops(&nodes);
2140                 invalid_last_hops.push(invalid_last_hop);
2141                 {
2142                         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)) {
2143                                 assert_eq!(err, "Last hop cannot have a payee as a source.");
2144                         } else { panic!(); }
2145                 }
2146
2147                 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();
2148                 assert_eq!(route.paths[0].len(), 5);
2149
2150                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2151                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2152                 assert_eq!(route.paths[0][0].fee_msat, 100);
2153                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2154                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2155                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2156
2157                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2158                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2159                 assert_eq!(route.paths[0][1].fee_msat, 0);
2160                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2161                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2162                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2163
2164                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2165                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2166                 assert_eq!(route.paths[0][2].fee_msat, 0);
2167                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2168                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2169                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2170
2171                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2172                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2173                 assert_eq!(route.paths[0][3].fee_msat, 0);
2174                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2175                 // If we have a peer in the node map, we'll use their features here since we don't have
2176                 // a way of figuring out their features from the invoice:
2177                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2178                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2179
2180                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2181                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2182                 assert_eq!(route.paths[0][4].fee_msat, 100);
2183                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2184                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2185                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2186         }
2187
2188         #[test]
2189         fn our_chans_last_hop_connect_test() {
2190                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2191                 let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
2192
2193                 // Simple test with outbound channel to 4 to test that last_hops and first_hops connect
2194                 let our_chans = vec![channelmanager::ChannelDetails {
2195                         channel_id: [0; 32],
2196                         short_channel_id: Some(42),
2197                         remote_network_id: nodes[3].clone(),
2198                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2199                         channel_value_satoshis: 0,
2200                         user_id: 0,
2201                         outbound_capacity_msat: 250_000_000,
2202                         inbound_capacity_msat: 0,
2203                         is_live: true,
2204                         counterparty_forwarding_info: None,
2205                 }];
2206                 let mut last_hops = last_hops(&nodes);
2207                 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();
2208                 assert_eq!(route.paths[0].len(), 2);
2209
2210                 assert_eq!(route.paths[0][0].pubkey, nodes[3]);
2211                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2212                 assert_eq!(route.paths[0][0].fee_msat, 0);
2213                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2214                 assert_eq!(route.paths[0][0].node_features.le_flags(), &vec![0b11]);
2215                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &Vec::<u8>::new()); // No feature flags will meet the relevant-to-channel conversion
2216
2217                 assert_eq!(route.paths[0][1].pubkey, nodes[6]);
2218                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2219                 assert_eq!(route.paths[0][1].fee_msat, 100);
2220                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2221                 assert_eq!(route.paths[0][1].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2222                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2223
2224                 last_hops[0].fees.base_msat = 1000;
2225
2226                 // Revert to via 6 as the fee on 8 goes up
2227                 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();
2228                 assert_eq!(route.paths[0].len(), 4);
2229
2230                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2231                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2232                 assert_eq!(route.paths[0][0].fee_msat, 200); // fee increased as its % of value transferred across node
2233                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2234                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2235                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2236
2237                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2238                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2239                 assert_eq!(route.paths[0][1].fee_msat, 100);
2240                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (7 << 8) | 1);
2241                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2242                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2243
2244                 assert_eq!(route.paths[0][2].pubkey, nodes[5]);
2245                 assert_eq!(route.paths[0][2].short_channel_id, 7);
2246                 assert_eq!(route.paths[0][2].fee_msat, 0);
2247                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (10 << 8) | 1);
2248                 // If we have a peer in the node map, we'll use their features here since we don't have
2249                 // a way of figuring out their features from the invoice:
2250                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
2251                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(7));
2252
2253                 assert_eq!(route.paths[0][3].pubkey, nodes[6]);
2254                 assert_eq!(route.paths[0][3].short_channel_id, 10);
2255                 assert_eq!(route.paths[0][3].fee_msat, 100);
2256                 assert_eq!(route.paths[0][3].cltv_expiry_delta, 42);
2257                 assert_eq!(route.paths[0][3].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2258                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2259
2260                 // ...but still use 8 for larger payments as 6 has a variable feerate
2261                 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();
2262                 assert_eq!(route.paths[0].len(), 5);
2263
2264                 assert_eq!(route.paths[0][0].pubkey, nodes[1]);
2265                 assert_eq!(route.paths[0][0].short_channel_id, 2);
2266                 assert_eq!(route.paths[0][0].fee_msat, 3000);
2267                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (4 << 8) | 1);
2268                 assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(2));
2269                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(2));
2270
2271                 assert_eq!(route.paths[0][1].pubkey, nodes[2]);
2272                 assert_eq!(route.paths[0][1].short_channel_id, 4);
2273                 assert_eq!(route.paths[0][1].fee_msat, 0);
2274                 assert_eq!(route.paths[0][1].cltv_expiry_delta, (6 << 8) | 1);
2275                 assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
2276                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(4));
2277
2278                 assert_eq!(route.paths[0][2].pubkey, nodes[4]);
2279                 assert_eq!(route.paths[0][2].short_channel_id, 6);
2280                 assert_eq!(route.paths[0][2].fee_msat, 0);
2281                 assert_eq!(route.paths[0][2].cltv_expiry_delta, (11 << 8) | 1);
2282                 assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(5));
2283                 assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(6));
2284
2285                 assert_eq!(route.paths[0][3].pubkey, nodes[3]);
2286                 assert_eq!(route.paths[0][3].short_channel_id, 11);
2287                 assert_eq!(route.paths[0][3].fee_msat, 1000);
2288                 assert_eq!(route.paths[0][3].cltv_expiry_delta, (8 << 8) | 1);
2289                 // If we have a peer in the node map, we'll use their features here since we don't have
2290                 // a way of figuring out their features from the invoice:
2291                 assert_eq!(route.paths[0][3].node_features.le_flags(), &id_to_feature_flags(4));
2292                 assert_eq!(route.paths[0][3].channel_features.le_flags(), &id_to_feature_flags(11));
2293
2294                 assert_eq!(route.paths[0][4].pubkey, nodes[6]);
2295                 assert_eq!(route.paths[0][4].short_channel_id, 8);
2296                 assert_eq!(route.paths[0][4].fee_msat, 2000);
2297                 assert_eq!(route.paths[0][4].cltv_expiry_delta, 42);
2298                 assert_eq!(route.paths[0][4].node_features.le_flags(), &Vec::<u8>::new()); // We dont pass flags in from invoices yet
2299                 assert_eq!(route.paths[0][4].channel_features.le_flags(), &Vec::<u8>::new()); // We can't learn any flags from invoices, sadly
2300         }
2301
2302         #[test]
2303         fn unannounced_path_test() {
2304                 // We should be able to send a payment to a destination without any help of a routing graph
2305                 // if we have a channel with a common counterparty that appears in the first and last hop
2306                 // hints.
2307                 let source_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 41).repeat(32)).unwrap()[..]).unwrap());
2308                 let middle_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 42).repeat(32)).unwrap()[..]).unwrap());
2309                 let target_node_id = PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&hex::decode(format!("{:02}", 43).repeat(32)).unwrap()[..]).unwrap());
2310
2311                 // If we specify a channel to a middle hop, that overrides our local channel view and that gets used
2312                 let last_hops = vec![RouteHint {
2313                         src_node_id: middle_node_id,
2314                         short_channel_id: 8,
2315                         fees: RoutingFees {
2316                                 base_msat: 1000,
2317                                 proportional_millionths: 0,
2318                         },
2319                         cltv_expiry_delta: (8 << 8) | 1,
2320                         htlc_minimum_msat: None,
2321                         htlc_maximum_msat: None,
2322                 }];
2323                 let our_chans = vec![channelmanager::ChannelDetails {
2324                         channel_id: [0; 32],
2325                         short_channel_id: Some(42),
2326                         remote_network_id: middle_node_id,
2327                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2328                         channel_value_satoshis: 100000,
2329                         user_id: 0,
2330                         outbound_capacity_msat: 100000,
2331                         inbound_capacity_msat: 100000,
2332                         is_live: true,
2333                         counterparty_forwarding_info: None,
2334                 }];
2335                 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();
2336
2337                 assert_eq!(route.paths[0].len(), 2);
2338
2339                 assert_eq!(route.paths[0][0].pubkey, middle_node_id);
2340                 assert_eq!(route.paths[0][0].short_channel_id, 42);
2341                 assert_eq!(route.paths[0][0].fee_msat, 1000);
2342                 assert_eq!(route.paths[0][0].cltv_expiry_delta, (8 << 8) | 1);
2343                 assert_eq!(route.paths[0][0].node_features.le_flags(), &[0b11]);
2344                 assert_eq!(route.paths[0][0].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2345
2346                 assert_eq!(route.paths[0][1].pubkey, target_node_id);
2347                 assert_eq!(route.paths[0][1].short_channel_id, 8);
2348                 assert_eq!(route.paths[0][1].fee_msat, 100);
2349                 assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
2350                 assert_eq!(route.paths[0][1].node_features.le_flags(), &[0; 0]); // We dont pass flags in from invoices yet
2351                 assert_eq!(route.paths[0][1].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
2352         }
2353
2354         #[test]
2355         fn available_amount_while_routing_test() {
2356                 // Tests whether we choose the correct available channel amount while routing.
2357
2358                 let (secp_ctx, mut net_graph_msg_handler, chain_monitor, logger) = build_graph();
2359                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2360
2361                 // We will use a simple single-path route from
2362                 // our node to node2 via node0: channels {1, 3}.
2363
2364                 // First disable all other paths.
2365                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2366                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2367                         short_channel_id: 2,
2368                         timestamp: 2,
2369                         flags: 2,
2370                         cltv_expiry_delta: 0,
2371                         htlc_minimum_msat: 0,
2372                         htlc_maximum_msat: OptionalField::Present(100_000),
2373                         fee_base_msat: 0,
2374                         fee_proportional_millionths: 0,
2375                         excess_data: Vec::new()
2376                 });
2377                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2378                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2379                         short_channel_id: 12,
2380                         timestamp: 2,
2381                         flags: 2,
2382                         cltv_expiry_delta: 0,
2383                         htlc_minimum_msat: 0,
2384                         htlc_maximum_msat: OptionalField::Present(100_000),
2385                         fee_base_msat: 0,
2386                         fee_proportional_millionths: 0,
2387                         excess_data: Vec::new()
2388                 });
2389
2390                 // Make the first channel (#1) very permissive,
2391                 // and we will be testing all limits on the second channel.
2392                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2393                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2394                         short_channel_id: 1,
2395                         timestamp: 2,
2396                         flags: 0,
2397                         cltv_expiry_delta: 0,
2398                         htlc_minimum_msat: 0,
2399                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2400                         fee_base_msat: 0,
2401                         fee_proportional_millionths: 0,
2402                         excess_data: Vec::new()
2403                 });
2404
2405                 // First, let's see if routing works if we have absolutely no idea about the available amount.
2406                 // In this case, it should be set to 250_000 sats.
2407                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2408                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2409                         short_channel_id: 3,
2410                         timestamp: 2,
2411                         flags: 0,
2412                         cltv_expiry_delta: 0,
2413                         htlc_minimum_msat: 0,
2414                         htlc_maximum_msat: OptionalField::Absent,
2415                         fee_base_msat: 0,
2416                         fee_proportional_millionths: 0,
2417                         excess_data: Vec::new()
2418                 });
2419
2420                 {
2421                         // Attempt to route more than available results in a failure.
2422                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2423                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000_001, 42, Arc::clone(&logger)) {
2424                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2425                         } else { panic!(); }
2426                 }
2427
2428                 {
2429                         // Now, attempt to route an exact amount we have should be fine.
2430                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2431                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000_000, 42, Arc::clone(&logger)).unwrap();
2432                         assert_eq!(route.paths.len(), 1);
2433                         let path = route.paths.last().unwrap();
2434                         assert_eq!(path.len(), 2);
2435                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2436                         assert_eq!(path.last().unwrap().fee_msat, 250_000_000);
2437                 }
2438
2439                 // Check that setting outbound_capacity_msat in first_hops limits the channels.
2440                 // Disable channel #1 and use another first hop.
2441                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2442                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2443                         short_channel_id: 1,
2444                         timestamp: 3,
2445                         flags: 2,
2446                         cltv_expiry_delta: 0,
2447                         htlc_minimum_msat: 0,
2448                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2449                         fee_base_msat: 0,
2450                         fee_proportional_millionths: 0,
2451                         excess_data: Vec::new()
2452                 });
2453
2454                 // Now, limit the first_hop by the outbound_capacity_msat of 200_000 sats.
2455                 let our_chans = vec![channelmanager::ChannelDetails {
2456                         channel_id: [0; 32],
2457                         short_channel_id: Some(42),
2458                         remote_network_id: nodes[0].clone(),
2459                         counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
2460                         channel_value_satoshis: 0,
2461                         user_id: 0,
2462                         outbound_capacity_msat: 200_000_000,
2463                         inbound_capacity_msat: 0,
2464                         is_live: true,
2465                         counterparty_forwarding_info: None,
2466                 }];
2467
2468                 {
2469                         // Attempt to route more than available results in a failure.
2470                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2471                                         Some(InvoiceFeatures::known()), Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_001, 42, Arc::clone(&logger)) {
2472                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2473                         } else { panic!(); }
2474                 }
2475
2476                 {
2477                         // Now, attempt to route an exact amount we have should be fine.
2478                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2479                                 Some(InvoiceFeatures::known()), Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_000, 42, Arc::clone(&logger)).unwrap();
2480                         assert_eq!(route.paths.len(), 1);
2481                         let path = route.paths.last().unwrap();
2482                         assert_eq!(path.len(), 2);
2483                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2484                         assert_eq!(path.last().unwrap().fee_msat, 200_000_000);
2485                 }
2486
2487                 // Enable channel #1 back.
2488                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2489                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2490                         short_channel_id: 1,
2491                         timestamp: 4,
2492                         flags: 0,
2493                         cltv_expiry_delta: 0,
2494                         htlc_minimum_msat: 0,
2495                         htlc_maximum_msat: OptionalField::Present(1_000_000_000),
2496                         fee_base_msat: 0,
2497                         fee_proportional_millionths: 0,
2498                         excess_data: Vec::new()
2499                 });
2500
2501
2502                 // Now let's see if routing works if we know only htlc_maximum_msat.
2503                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2504                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2505                         short_channel_id: 3,
2506                         timestamp: 3,
2507                         flags: 0,
2508                         cltv_expiry_delta: 0,
2509                         htlc_minimum_msat: 0,
2510                         htlc_maximum_msat: OptionalField::Present(15_000),
2511                         fee_base_msat: 0,
2512                         fee_proportional_millionths: 0,
2513                         excess_data: Vec::new()
2514                 });
2515
2516                 {
2517                         // Attempt to route more than available results in a failure.
2518                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2519                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 15_001, 42, Arc::clone(&logger)) {
2520                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2521                         } else { panic!(); }
2522                 }
2523
2524                 {
2525                         // Now, attempt to route an exact amount we have should be fine.
2526                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2527                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 15_000, 42, Arc::clone(&logger)).unwrap();
2528                         assert_eq!(route.paths.len(), 1);
2529                         let path = route.paths.last().unwrap();
2530                         assert_eq!(path.len(), 2);
2531                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2532                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
2533                 }
2534
2535                 // Now let's see if routing works if we know only capacity from the UTXO.
2536
2537                 // We can't change UTXO capacity on the fly, so we'll disable
2538                 // the existing channel and add another one with the capacity we need.
2539                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2540                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2541                         short_channel_id: 3,
2542                         timestamp: 4,
2543                         flags: 2,
2544                         cltv_expiry_delta: 0,
2545                         htlc_minimum_msat: 0,
2546                         htlc_maximum_msat: OptionalField::Absent,
2547                         fee_base_msat: 0,
2548                         fee_proportional_millionths: 0,
2549                         excess_data: Vec::new()
2550                 });
2551
2552                 let good_script = Builder::new().push_opcode(opcodes::all::OP_PUSHNUM_2)
2553                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[0]).serialize())
2554                 .push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[2]).serialize())
2555                 .push_opcode(opcodes::all::OP_PUSHNUM_2)
2556                 .push_opcode(opcodes::all::OP_CHECKMULTISIG).into_script().to_v0_p2wsh();
2557
2558                 *chain_monitor.utxo_ret.lock().unwrap() = Ok(TxOut { value: 15, script_pubkey: good_script.clone() });
2559                 net_graph_msg_handler.add_chain_access(Some(chain_monitor));
2560
2561                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 333);
2562                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2563                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2564                         short_channel_id: 333,
2565                         timestamp: 1,
2566                         flags: 0,
2567                         cltv_expiry_delta: (3 << 8) | 1,
2568                         htlc_minimum_msat: 0,
2569                         htlc_maximum_msat: OptionalField::Absent,
2570                         fee_base_msat: 0,
2571                         fee_proportional_millionths: 0,
2572                         excess_data: Vec::new()
2573                 });
2574                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2575                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2576                         short_channel_id: 333,
2577                         timestamp: 1,
2578                         flags: 1,
2579                         cltv_expiry_delta: (3 << 8) | 2,
2580                         htlc_minimum_msat: 0,
2581                         htlc_maximum_msat: OptionalField::Absent,
2582                         fee_base_msat: 100,
2583                         fee_proportional_millionths: 0,
2584                         excess_data: Vec::new()
2585                 });
2586
2587                 {
2588                         // Attempt to route more than available results in a failure.
2589                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2590                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 15_001, 42, Arc::clone(&logger)) {
2591                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2592                         } else { panic!(); }
2593                 }
2594
2595                 {
2596                         // Now, attempt to route an exact amount we have should be fine.
2597                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2598                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 15_000, 42, Arc::clone(&logger)).unwrap();
2599                         assert_eq!(route.paths.len(), 1);
2600                         let path = route.paths.last().unwrap();
2601                         assert_eq!(path.len(), 2);
2602                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2603                         assert_eq!(path.last().unwrap().fee_msat, 15_000);
2604                 }
2605
2606                 // Now let's see if routing chooses htlc_maximum_msat over UTXO capacity.
2607                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2608                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2609                         short_channel_id: 333,
2610                         timestamp: 6,
2611                         flags: 0,
2612                         cltv_expiry_delta: 0,
2613                         htlc_minimum_msat: 0,
2614                         htlc_maximum_msat: OptionalField::Present(10_000),
2615                         fee_base_msat: 0,
2616                         fee_proportional_millionths: 0,
2617                         excess_data: Vec::new()
2618                 });
2619
2620                 {
2621                         // Attempt to route more than available results in a failure.
2622                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2623                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 10_001, 42, Arc::clone(&logger)) {
2624                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2625                         } else { panic!(); }
2626                 }
2627
2628                 {
2629                         // Now, attempt to route an exact amount we have should be fine.
2630                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2631                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 10_000, 42, Arc::clone(&logger)).unwrap();
2632                         assert_eq!(route.paths.len(), 1);
2633                         let path = route.paths.last().unwrap();
2634                         assert_eq!(path.len(), 2);
2635                         assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2636                         assert_eq!(path.last().unwrap().fee_msat, 10_000);
2637                 }
2638         }
2639
2640         #[test]
2641         fn available_liquidity_last_hop_test() {
2642                 // Check that available liquidity properly limits the path even when only
2643                 // one of the latter hops is limited.
2644                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2645                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2646
2647                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
2648                 // {12, 13, 11} have the capacities of 100, {6} has a capacity of 50.
2649                 // Total capacity: 50 sats.
2650
2651                 // Disable other potential paths.
2652                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2653                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2654                         short_channel_id: 2,
2655                         timestamp: 2,
2656                         flags: 2,
2657                         cltv_expiry_delta: 0,
2658                         htlc_minimum_msat: 0,
2659                         htlc_maximum_msat: OptionalField::Present(100_000),
2660                         fee_base_msat: 0,
2661                         fee_proportional_millionths: 0,
2662                         excess_data: Vec::new()
2663                 });
2664                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2665                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2666                         short_channel_id: 7,
2667                         timestamp: 2,
2668                         flags: 2,
2669                         cltv_expiry_delta: 0,
2670                         htlc_minimum_msat: 0,
2671                         htlc_maximum_msat: OptionalField::Present(100_000),
2672                         fee_base_msat: 0,
2673                         fee_proportional_millionths: 0,
2674                         excess_data: Vec::new()
2675                 });
2676
2677                 // Limit capacities
2678
2679                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2680                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2681                         short_channel_id: 12,
2682                         timestamp: 2,
2683                         flags: 0,
2684                         cltv_expiry_delta: 0,
2685                         htlc_minimum_msat: 0,
2686                         htlc_maximum_msat: OptionalField::Present(100_000),
2687                         fee_base_msat: 0,
2688                         fee_proportional_millionths: 0,
2689                         excess_data: Vec::new()
2690                 });
2691                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2692                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2693                         short_channel_id: 13,
2694                         timestamp: 2,
2695                         flags: 0,
2696                         cltv_expiry_delta: 0,
2697                         htlc_minimum_msat: 0,
2698                         htlc_maximum_msat: OptionalField::Present(100_000),
2699                         fee_base_msat: 0,
2700                         fee_proportional_millionths: 0,
2701                         excess_data: Vec::new()
2702                 });
2703
2704                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2705                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2706                         short_channel_id: 6,
2707                         timestamp: 2,
2708                         flags: 0,
2709                         cltv_expiry_delta: 0,
2710                         htlc_minimum_msat: 0,
2711                         htlc_maximum_msat: OptionalField::Present(50_000),
2712                         fee_base_msat: 0,
2713                         fee_proportional_millionths: 0,
2714                         excess_data: Vec::new()
2715                 });
2716                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
2717                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2718                         short_channel_id: 11,
2719                         timestamp: 2,
2720                         flags: 0,
2721                         cltv_expiry_delta: 0,
2722                         htlc_minimum_msat: 0,
2723                         htlc_maximum_msat: OptionalField::Present(100_000),
2724                         fee_base_msat: 0,
2725                         fee_proportional_millionths: 0,
2726                         excess_data: Vec::new()
2727                 });
2728                 {
2729                         // Attempt to route more than available results in a failure.
2730                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2731                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 60_000, 42, Arc::clone(&logger)) {
2732                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2733                         } else { panic!(); }
2734                 }
2735
2736                 {
2737                         // Now, attempt to route 49 sats (just a bit below the capacity).
2738                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2739                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 49_000, 42, Arc::clone(&logger)).unwrap();
2740                         assert_eq!(route.paths.len(), 1);
2741                         let mut total_amount_paid_msat = 0;
2742                         for path in &route.paths {
2743                                 assert_eq!(path.len(), 4);
2744                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
2745                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2746                         }
2747                         assert_eq!(total_amount_paid_msat, 49_000);
2748                 }
2749
2750                 {
2751                         // Attempt to route an exact amount is also fine
2752                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
2753                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
2754                         assert_eq!(route.paths.len(), 1);
2755                         let mut total_amount_paid_msat = 0;
2756                         for path in &route.paths {
2757                                 assert_eq!(path.len(), 4);
2758                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
2759                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2760                         }
2761                         assert_eq!(total_amount_paid_msat, 50_000);
2762                 }
2763         }
2764
2765         #[test]
2766         fn ignore_fee_first_hop_test() {
2767                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2768                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2769
2770                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
2771                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2772                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2773                         short_channel_id: 1,
2774                         timestamp: 2,
2775                         flags: 0,
2776                         cltv_expiry_delta: 0,
2777                         htlc_minimum_msat: 0,
2778                         htlc_maximum_msat: OptionalField::Present(100_000),
2779                         fee_base_msat: 1_000_000,
2780                         fee_proportional_millionths: 0,
2781                         excess_data: Vec::new()
2782                 });
2783                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2784                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2785                         short_channel_id: 3,
2786                         timestamp: 2,
2787                         flags: 0,
2788                         cltv_expiry_delta: 0,
2789                         htlc_minimum_msat: 0,
2790                         htlc_maximum_msat: OptionalField::Present(50_000),
2791                         fee_base_msat: 0,
2792                         fee_proportional_millionths: 0,
2793                         excess_data: Vec::new()
2794                 });
2795
2796                 {
2797                         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();
2798                         assert_eq!(route.paths.len(), 1);
2799                         let mut total_amount_paid_msat = 0;
2800                         for path in &route.paths {
2801                                 assert_eq!(path.len(), 2);
2802                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2803                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2804                         }
2805                         assert_eq!(total_amount_paid_msat, 50_000);
2806                 }
2807         }
2808
2809         #[test]
2810         fn simple_mpp_route_test() {
2811                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2812                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2813
2814                 // We need a route consisting of 3 paths:
2815                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
2816                 // To achieve this, the amount being transferred should be around
2817                 // the total capacity of these 3 paths.
2818
2819                 // First, we set limits on these (previously unlimited) channels.
2820                 // Their aggregate capacity will be 50 + 60 + 180 = 290 sats.
2821
2822                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
2823                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2824                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2825                         short_channel_id: 1,
2826                         timestamp: 2,
2827                         flags: 0,
2828                         cltv_expiry_delta: 0,
2829                         htlc_minimum_msat: 0,
2830                         htlc_maximum_msat: OptionalField::Present(100_000),
2831                         fee_base_msat: 0,
2832                         fee_proportional_millionths: 0,
2833                         excess_data: Vec::new()
2834                 });
2835                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2836                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2837                         short_channel_id: 3,
2838                         timestamp: 2,
2839                         flags: 0,
2840                         cltv_expiry_delta: 0,
2841                         htlc_minimum_msat: 0,
2842                         htlc_maximum_msat: OptionalField::Present(50_000),
2843                         fee_base_msat: 0,
2844                         fee_proportional_millionths: 0,
2845                         excess_data: Vec::new()
2846                 });
2847
2848                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats
2849                 // (total limit 60).
2850                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2851                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2852                         short_channel_id: 12,
2853                         timestamp: 2,
2854                         flags: 0,
2855                         cltv_expiry_delta: 0,
2856                         htlc_minimum_msat: 0,
2857                         htlc_maximum_msat: OptionalField::Present(60_000),
2858                         fee_base_msat: 0,
2859                         fee_proportional_millionths: 0,
2860                         excess_data: Vec::new()
2861                 });
2862                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
2863                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2864                         short_channel_id: 13,
2865                         timestamp: 2,
2866                         flags: 0,
2867                         cltv_expiry_delta: 0,
2868                         htlc_minimum_msat: 0,
2869                         htlc_maximum_msat: OptionalField::Present(60_000),
2870                         fee_base_msat: 0,
2871                         fee_proportional_millionths: 0,
2872                         excess_data: Vec::new()
2873                 });
2874
2875                 // Path via node1 is channels {2, 4}. Limit them to 200 and 180 sats
2876                 // (total capacity 180 sats).
2877                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2878                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2879                         short_channel_id: 2,
2880                         timestamp: 2,
2881                         flags: 0,
2882                         cltv_expiry_delta: 0,
2883                         htlc_minimum_msat: 0,
2884                         htlc_maximum_msat: OptionalField::Present(200_000),
2885                         fee_base_msat: 0,
2886                         fee_proportional_millionths: 0,
2887                         excess_data: Vec::new()
2888                 });
2889                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
2890                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2891                         short_channel_id: 4,
2892                         timestamp: 2,
2893                         flags: 0,
2894                         cltv_expiry_delta: 0,
2895                         htlc_minimum_msat: 0,
2896                         htlc_maximum_msat: OptionalField::Present(180_000),
2897                         fee_base_msat: 0,
2898                         fee_proportional_millionths: 0,
2899                         excess_data: Vec::new()
2900                 });
2901
2902                 {
2903                         // Attempt to route more than available results in a failure.
2904                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(),
2905                                         &nodes[2], Some(InvoiceFeatures::known()), None, &Vec::new(), 300_000, 42, Arc::clone(&logger)) {
2906                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
2907                         } else { panic!(); }
2908                 }
2909
2910                 {
2911                         // Now, attempt to route 250 sats (just a bit below the capacity).
2912                         // Our algorithm should provide us with these 3 paths.
2913                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2914                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 250_000, 42, Arc::clone(&logger)).unwrap();
2915                         assert_eq!(route.paths.len(), 3);
2916                         let mut total_amount_paid_msat = 0;
2917                         for path in &route.paths {
2918                                 assert_eq!(path.len(), 2);
2919                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2920                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2921                         }
2922                         assert_eq!(total_amount_paid_msat, 250_000);
2923                 }
2924
2925                 {
2926                         // Attempt to route an exact amount is also fine
2927                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
2928                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 290_000, 42, Arc::clone(&logger)).unwrap();
2929                         assert_eq!(route.paths.len(), 3);
2930                         let mut total_amount_paid_msat = 0;
2931                         for path in &route.paths {
2932                                 assert_eq!(path.len(), 2);
2933                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
2934                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
2935                         }
2936                         assert_eq!(total_amount_paid_msat, 290_000);
2937                 }
2938         }
2939
2940         #[test]
2941         fn long_mpp_route_test() {
2942                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
2943                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
2944
2945                 // We need a route consisting of 3 paths:
2946                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
2947                 // Note that these paths overlap (channels 5, 12, 13).
2948                 // We will route 300 sats.
2949                 // Each path will have 100 sats capacity, those channels which
2950                 // are used twice will have 200 sats capacity.
2951
2952                 // Disable other potential paths.
2953                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2954                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2955                         short_channel_id: 2,
2956                         timestamp: 2,
2957                         flags: 2,
2958                         cltv_expiry_delta: 0,
2959                         htlc_minimum_msat: 0,
2960                         htlc_maximum_msat: OptionalField::Present(100_000),
2961                         fee_base_msat: 0,
2962                         fee_proportional_millionths: 0,
2963                         excess_data: Vec::new()
2964                 });
2965                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
2966                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2967                         short_channel_id: 7,
2968                         timestamp: 2,
2969                         flags: 2,
2970                         cltv_expiry_delta: 0,
2971                         htlc_minimum_msat: 0,
2972                         htlc_maximum_msat: OptionalField::Present(100_000),
2973                         fee_base_msat: 0,
2974                         fee_proportional_millionths: 0,
2975                         excess_data: Vec::new()
2976                 });
2977
2978                 // Path via {node0, node2} is channels {1, 3, 5}.
2979                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
2980                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2981                         short_channel_id: 1,
2982                         timestamp: 2,
2983                         flags: 0,
2984                         cltv_expiry_delta: 0,
2985                         htlc_minimum_msat: 0,
2986                         htlc_maximum_msat: OptionalField::Present(100_000),
2987                         fee_base_msat: 0,
2988                         fee_proportional_millionths: 0,
2989                         excess_data: Vec::new()
2990                 });
2991                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
2992                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
2993                         short_channel_id: 3,
2994                         timestamp: 2,
2995                         flags: 0,
2996                         cltv_expiry_delta: 0,
2997                         htlc_minimum_msat: 0,
2998                         htlc_maximum_msat: OptionalField::Present(100_000),
2999                         fee_base_msat: 0,
3000                         fee_proportional_millionths: 0,
3001                         excess_data: Vec::new()
3002                 });
3003
3004                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3005                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3006                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3007                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3008                         short_channel_id: 5,
3009                         timestamp: 2,
3010                         flags: 0,
3011                         cltv_expiry_delta: 0,
3012                         htlc_minimum_msat: 0,
3013                         htlc_maximum_msat: OptionalField::Present(200_000),
3014                         fee_base_msat: 0,
3015                         fee_proportional_millionths: 0,
3016                         excess_data: Vec::new()
3017                 });
3018
3019                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3020                 // Add 100 sats to the capacities of {12, 13}, because these channels
3021                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3022                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3023                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3024                         short_channel_id: 12,
3025                         timestamp: 2,
3026                         flags: 0,
3027                         cltv_expiry_delta: 0,
3028                         htlc_minimum_msat: 0,
3029                         htlc_maximum_msat: OptionalField::Present(200_000),
3030                         fee_base_msat: 0,
3031                         fee_proportional_millionths: 0,
3032                         excess_data: Vec::new()
3033                 });
3034                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3035                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3036                         short_channel_id: 13,
3037                         timestamp: 2,
3038                         flags: 0,
3039                         cltv_expiry_delta: 0,
3040                         htlc_minimum_msat: 0,
3041                         htlc_maximum_msat: OptionalField::Present(200_000),
3042                         fee_base_msat: 0,
3043                         fee_proportional_millionths: 0,
3044                         excess_data: Vec::new()
3045                 });
3046
3047                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3048                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3049                         short_channel_id: 6,
3050                         timestamp: 2,
3051                         flags: 0,
3052                         cltv_expiry_delta: 0,
3053                         htlc_minimum_msat: 0,
3054                         htlc_maximum_msat: OptionalField::Present(100_000),
3055                         fee_base_msat: 0,
3056                         fee_proportional_millionths: 0,
3057                         excess_data: Vec::new()
3058                 });
3059                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3060                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3061                         short_channel_id: 11,
3062                         timestamp: 2,
3063                         flags: 0,
3064                         cltv_expiry_delta: 0,
3065                         htlc_minimum_msat: 0,
3066                         htlc_maximum_msat: OptionalField::Present(100_000),
3067                         fee_base_msat: 0,
3068                         fee_proportional_millionths: 0,
3069                         excess_data: Vec::new()
3070                 });
3071
3072                 // Path via {node7, node2} is channels {12, 13, 5}.
3073                 // We already limited them to 200 sats (they are used twice for 100 sats).
3074                 // Nothing to do here.
3075
3076                 {
3077                         // Attempt to route more than available results in a failure.
3078                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3079                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 350_000, 42, Arc::clone(&logger)) {
3080                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3081                         } else { panic!(); }
3082                 }
3083
3084                 {
3085                         // Now, attempt to route 300 sats (exact amount we can route).
3086                         // Our algorithm should provide us with these 3 paths, 100 sats each.
3087                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3088                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 300_000, 42, Arc::clone(&logger)).unwrap();
3089                         assert_eq!(route.paths.len(), 3);
3090
3091                         let mut total_amount_paid_msat = 0;
3092                         for path in &route.paths {
3093                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3094                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3095                         }
3096                         assert_eq!(total_amount_paid_msat, 300_000);
3097                 }
3098
3099         }
3100
3101         #[test]
3102         fn mpp_cheaper_route_test() {
3103                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3104                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3105
3106                 // This test checks that if we have two cheaper paths and one more expensive path,
3107                 // so that liquidity-wise any 2 of 3 combination is sufficient,
3108                 // two cheaper paths will be taken.
3109                 // These paths have equal available liquidity.
3110
3111                 // We need a combination of 3 paths:
3112                 // From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
3113                 // Note that these paths overlap (channels 5, 12, 13).
3114                 // Each path will have 100 sats capacity, those channels which
3115                 // are used twice will have 200 sats capacity.
3116
3117                 // Disable other potential paths.
3118                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3119                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3120                         short_channel_id: 2,
3121                         timestamp: 2,
3122                         flags: 2,
3123                         cltv_expiry_delta: 0,
3124                         htlc_minimum_msat: 0,
3125                         htlc_maximum_msat: OptionalField::Present(100_000),
3126                         fee_base_msat: 0,
3127                         fee_proportional_millionths: 0,
3128                         excess_data: Vec::new()
3129                 });
3130                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3131                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3132                         short_channel_id: 7,
3133                         timestamp: 2,
3134                         flags: 2,
3135                         cltv_expiry_delta: 0,
3136                         htlc_minimum_msat: 0,
3137                         htlc_maximum_msat: OptionalField::Present(100_000),
3138                         fee_base_msat: 0,
3139                         fee_proportional_millionths: 0,
3140                         excess_data: Vec::new()
3141                 });
3142
3143                 // Path via {node0, node2} is channels {1, 3, 5}.
3144                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3145                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3146                         short_channel_id: 1,
3147                         timestamp: 2,
3148                         flags: 0,
3149                         cltv_expiry_delta: 0,
3150                         htlc_minimum_msat: 0,
3151                         htlc_maximum_msat: OptionalField::Present(100_000),
3152                         fee_base_msat: 0,
3153                         fee_proportional_millionths: 0,
3154                         excess_data: Vec::new()
3155                 });
3156                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3157                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3158                         short_channel_id: 3,
3159                         timestamp: 2,
3160                         flags: 0,
3161                         cltv_expiry_delta: 0,
3162                         htlc_minimum_msat: 0,
3163                         htlc_maximum_msat: OptionalField::Present(100_000),
3164                         fee_base_msat: 0,
3165                         fee_proportional_millionths: 0,
3166                         excess_data: Vec::new()
3167                 });
3168
3169                 // Capacity of 200 sats because this channel will be used by 3rd path as well.
3170                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3171                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3172                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3173                         short_channel_id: 5,
3174                         timestamp: 2,
3175                         flags: 0,
3176                         cltv_expiry_delta: 0,
3177                         htlc_minimum_msat: 0,
3178                         htlc_maximum_msat: OptionalField::Present(200_000),
3179                         fee_base_msat: 0,
3180                         fee_proportional_millionths: 0,
3181                         excess_data: Vec::new()
3182                 });
3183
3184                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3185                 // Add 100 sats to the capacities of {12, 13}, because these channels
3186                 // are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
3187                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3188                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3189                         short_channel_id: 12,
3190                         timestamp: 2,
3191                         flags: 0,
3192                         cltv_expiry_delta: 0,
3193                         htlc_minimum_msat: 0,
3194                         htlc_maximum_msat: OptionalField::Present(200_000),
3195                         fee_base_msat: 0,
3196                         fee_proportional_millionths: 0,
3197                         excess_data: Vec::new()
3198                 });
3199                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3200                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3201                         short_channel_id: 13,
3202                         timestamp: 2,
3203                         flags: 0,
3204                         cltv_expiry_delta: 0,
3205                         htlc_minimum_msat: 0,
3206                         htlc_maximum_msat: OptionalField::Present(200_000),
3207                         fee_base_msat: 0,
3208                         fee_proportional_millionths: 0,
3209                         excess_data: Vec::new()
3210                 });
3211
3212                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3213                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3214                         short_channel_id: 6,
3215                         timestamp: 2,
3216                         flags: 0,
3217                         cltv_expiry_delta: 0,
3218                         htlc_minimum_msat: 0,
3219                         htlc_maximum_msat: OptionalField::Present(100_000),
3220                         fee_base_msat: 1_000,
3221                         fee_proportional_millionths: 0,
3222                         excess_data: Vec::new()
3223                 });
3224                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3225                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3226                         short_channel_id: 11,
3227                         timestamp: 2,
3228                         flags: 0,
3229                         cltv_expiry_delta: 0,
3230                         htlc_minimum_msat: 0,
3231                         htlc_maximum_msat: OptionalField::Present(100_000),
3232                         fee_base_msat: 0,
3233                         fee_proportional_millionths: 0,
3234                         excess_data: Vec::new()
3235                 });
3236
3237                 // Path via {node7, node2} is channels {12, 13, 5}.
3238                 // We already limited them to 200 sats (they are used twice for 100 sats).
3239                 // Nothing to do here.
3240
3241                 {
3242                         // Now, attempt to route 180 sats.
3243                         // Our algorithm should provide us with these 2 paths.
3244                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3245                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 180_000, 42, Arc::clone(&logger)).unwrap();
3246                         assert_eq!(route.paths.len(), 2);
3247
3248                         let mut total_value_transferred_msat = 0;
3249                         let mut total_paid_msat = 0;
3250                         for path in &route.paths {
3251                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3252                                 total_value_transferred_msat += path.last().unwrap().fee_msat;
3253                                 for hop in path {
3254                                         total_paid_msat += hop.fee_msat;
3255                                 }
3256                         }
3257                         // If we paid fee, this would be higher.
3258                         assert_eq!(total_value_transferred_msat, 180_000);
3259                         let total_fees_paid = total_paid_msat - total_value_transferred_msat;
3260                         assert_eq!(total_fees_paid, 0);
3261                 }
3262         }
3263
3264         #[test]
3265         fn fees_on_mpp_route_test() {
3266                 // This test makes sure that MPP algorithm properly takes into account
3267                 // fees charged on the channels, by making the fees impactful:
3268                 // if the fee is not properly accounted for, the behavior is different.
3269                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3270                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3271
3272                 // We need a route consisting of 2 paths:
3273                 // From our node to node3 via {node0, node2} and {node7, node2, node4}.
3274                 // We will route 200 sats, Each path will have 100 sats capacity.
3275
3276                 // This test is not particularly stable: e.g.,
3277                 // there's a way to route via {node0, node2, node4}.
3278                 // It works while pathfinding is deterministic, but can be broken otherwise.
3279                 // It's fine to ignore this concern for now.
3280
3281                 // Disable other potential paths.
3282                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3283                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3284                         short_channel_id: 2,
3285                         timestamp: 2,
3286                         flags: 2,
3287                         cltv_expiry_delta: 0,
3288                         htlc_minimum_msat: 0,
3289                         htlc_maximum_msat: OptionalField::Present(100_000),
3290                         fee_base_msat: 0,
3291                         fee_proportional_millionths: 0,
3292                         excess_data: Vec::new()
3293                 });
3294
3295                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3296                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3297                         short_channel_id: 7,
3298                         timestamp: 2,
3299                         flags: 2,
3300                         cltv_expiry_delta: 0,
3301                         htlc_minimum_msat: 0,
3302                         htlc_maximum_msat: OptionalField::Present(100_000),
3303                         fee_base_msat: 0,
3304                         fee_proportional_millionths: 0,
3305                         excess_data: Vec::new()
3306                 });
3307
3308                 // Path via {node0, node2} is channels {1, 3, 5}.
3309                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3310                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3311                         short_channel_id: 1,
3312                         timestamp: 2,
3313                         flags: 0,
3314                         cltv_expiry_delta: 0,
3315                         htlc_minimum_msat: 0,
3316                         htlc_maximum_msat: OptionalField::Present(100_000),
3317                         fee_base_msat: 0,
3318                         fee_proportional_millionths: 0,
3319                         excess_data: Vec::new()
3320                 });
3321                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3322                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3323                         short_channel_id: 3,
3324                         timestamp: 2,
3325                         flags: 0,
3326                         cltv_expiry_delta: 0,
3327                         htlc_minimum_msat: 0,
3328                         htlc_maximum_msat: OptionalField::Present(100_000),
3329                         fee_base_msat: 0,
3330                         fee_proportional_millionths: 0,
3331                         excess_data: Vec::new()
3332                 });
3333
3334                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3335                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3336                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3337                         short_channel_id: 5,
3338                         timestamp: 2,
3339                         flags: 0,
3340                         cltv_expiry_delta: 0,
3341                         htlc_minimum_msat: 0,
3342                         htlc_maximum_msat: OptionalField::Present(100_000),
3343                         fee_base_msat: 0,
3344                         fee_proportional_millionths: 0,
3345                         excess_data: Vec::new()
3346                 });
3347
3348                 // Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
3349                 // All channels should be 100 sats capacity. But for the fee experiment,
3350                 // we'll add absolute fee of 150 sats paid for the use channel 6 (paid to node2 on channel 13).
3351                 // Since channel 12 allows to deliver only 250 sats to channel 13, channel 13 can transfer only
3352                 // 100 sats (and pay 150 sats in fees for the use of channel 6),
3353                 // so no matter how large are other channels,
3354                 // the whole path will be limited by 100 sats with just these 2 conditions:
3355                 // - channel 12 capacity is 250 sats
3356                 // - fee for channel 6 is 150 sats
3357                 // Let's test this by enforcing these 2 conditions and removing other limits.
3358                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3359                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3360                         short_channel_id: 12,
3361                         timestamp: 2,
3362                         flags: 0,
3363                         cltv_expiry_delta: 0,
3364                         htlc_minimum_msat: 0,
3365                         htlc_maximum_msat: OptionalField::Present(250_000),
3366                         fee_base_msat: 0,
3367                         fee_proportional_millionths: 0,
3368                         excess_data: Vec::new()
3369                 });
3370                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3371                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3372                         short_channel_id: 13,
3373                         timestamp: 2,
3374                         flags: 0,
3375                         cltv_expiry_delta: 0,
3376                         htlc_minimum_msat: 0,
3377                         htlc_maximum_msat: OptionalField::Absent,
3378                         fee_base_msat: 0,
3379                         fee_proportional_millionths: 0,
3380                         excess_data: Vec::new()
3381                 });
3382
3383                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3384                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3385                         short_channel_id: 6,
3386                         timestamp: 2,
3387                         flags: 0,
3388                         cltv_expiry_delta: 0,
3389                         htlc_minimum_msat: 0,
3390                         htlc_maximum_msat: OptionalField::Absent,
3391                         fee_base_msat: 150_000,
3392                         fee_proportional_millionths: 0,
3393                         excess_data: Vec::new()
3394                 });
3395                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3396                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3397                         short_channel_id: 11,
3398                         timestamp: 2,
3399                         flags: 0,
3400                         cltv_expiry_delta: 0,
3401                         htlc_minimum_msat: 0,
3402                         htlc_maximum_msat: OptionalField::Absent,
3403                         fee_base_msat: 0,
3404                         fee_proportional_millionths: 0,
3405                         excess_data: Vec::new()
3406                 });
3407
3408                 {
3409                         // Attempt to route more than available results in a failure.
3410                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3411                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 210_000, 42, Arc::clone(&logger)) {
3412                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3413                         } else { panic!(); }
3414                 }
3415
3416                 {
3417                         // Now, attempt to route 200 sats (exact amount we can route).
3418                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3],
3419                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 200_000, 42, Arc::clone(&logger)).unwrap();
3420                         assert_eq!(route.paths.len(), 2);
3421
3422                         let mut total_amount_paid_msat = 0;
3423                         for path in &route.paths {
3424                                 assert_eq!(path.last().unwrap().pubkey, nodes[3]);
3425                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3426                         }
3427                         assert_eq!(total_amount_paid_msat, 200_000);
3428                 }
3429
3430         }
3431
3432         #[test]
3433         fn drop_lowest_channel_mpp_route_test() {
3434                 // This test checks that low-capacity channel is dropped when after
3435                 // path finding we realize that we found more capacity than we need.
3436                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3437                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3438
3439                 // We need a route consisting of 3 paths:
3440                 // From our node to node2 via node0, node7, node1 (three paths one hop each).
3441
3442                 // The first and the second paths should be sufficient, but the third should be
3443                 // cheaper, so that we select it but drop later.
3444
3445                 // First, we set limits on these (previously unlimited) channels.
3446                 // Their aggregate capacity will be 50 + 60 + 20 = 130 sats.
3447
3448                 // Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50);
3449                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3450                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3451                         short_channel_id: 1,
3452                         timestamp: 2,
3453                         flags: 0,
3454                         cltv_expiry_delta: 0,
3455                         htlc_minimum_msat: 0,
3456                         htlc_maximum_msat: OptionalField::Present(100_000),
3457                         fee_base_msat: 0,
3458                         fee_proportional_millionths: 0,
3459                         excess_data: Vec::new()
3460                 });
3461                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
3462                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3463                         short_channel_id: 3,
3464                         timestamp: 2,
3465                         flags: 0,
3466                         cltv_expiry_delta: 0,
3467                         htlc_minimum_msat: 0,
3468                         htlc_maximum_msat: OptionalField::Present(50_000),
3469                         fee_base_msat: 100,
3470                         fee_proportional_millionths: 0,
3471                         excess_data: Vec::new()
3472                 });
3473
3474                 // Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats (total limit 60);
3475                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3476                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3477                         short_channel_id: 12,
3478                         timestamp: 2,
3479                         flags: 0,
3480                         cltv_expiry_delta: 0,
3481                         htlc_minimum_msat: 0,
3482                         htlc_maximum_msat: OptionalField::Present(60_000),
3483                         fee_base_msat: 100,
3484                         fee_proportional_millionths: 0,
3485                         excess_data: Vec::new()
3486                 });
3487                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
3488                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3489                         short_channel_id: 13,
3490                         timestamp: 2,
3491                         flags: 0,
3492                         cltv_expiry_delta: 0,
3493                         htlc_minimum_msat: 0,
3494                         htlc_maximum_msat: OptionalField::Present(60_000),
3495                         fee_base_msat: 0,
3496                         fee_proportional_millionths: 0,
3497                         excess_data: Vec::new()
3498                 });
3499
3500                 // Path via node1 is channels {2, 4}. Limit them to 20 and 20 sats (total capacity 20 sats).
3501                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3502                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3503                         short_channel_id: 2,
3504                         timestamp: 2,
3505                         flags: 0,
3506                         cltv_expiry_delta: 0,
3507                         htlc_minimum_msat: 0,
3508                         htlc_maximum_msat: OptionalField::Present(20_000),
3509                         fee_base_msat: 0,
3510                         fee_proportional_millionths: 0,
3511                         excess_data: Vec::new()
3512                 });
3513                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3514                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3515                         short_channel_id: 4,
3516                         timestamp: 2,
3517                         flags: 0,
3518                         cltv_expiry_delta: 0,
3519                         htlc_minimum_msat: 0,
3520                         htlc_maximum_msat: OptionalField::Present(20_000),
3521                         fee_base_msat: 0,
3522                         fee_proportional_millionths: 0,
3523                         excess_data: Vec::new()
3524                 });
3525
3526                 {
3527                         // Attempt to route more than available results in a failure.
3528                         if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3529                                         Some(InvoiceFeatures::known()), None, &Vec::new(), 150_000, 42, Arc::clone(&logger)) {
3530                                 assert_eq!(err, "Failed to find a sufficient route to the given destination");
3531                         } else { panic!(); }
3532                 }
3533
3534                 {
3535                         // Now, attempt to route 125 sats (just a bit below the capacity of 3 channels).
3536                         // Our algorithm should provide us with these 3 paths.
3537                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3538                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 125_000, 42, Arc::clone(&logger)).unwrap();
3539                         assert_eq!(route.paths.len(), 3);
3540                         let mut total_amount_paid_msat = 0;
3541                         for path in &route.paths {
3542                                 assert_eq!(path.len(), 2);
3543                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3544                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3545                         }
3546                         assert_eq!(total_amount_paid_msat, 125_000);
3547                 }
3548
3549                 {
3550                         // Attempt to route without the last small cheap channel
3551                         let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2],
3552                                 Some(InvoiceFeatures::known()), None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
3553                         assert_eq!(route.paths.len(), 2);
3554                         let mut total_amount_paid_msat = 0;
3555                         for path in &route.paths {
3556                                 assert_eq!(path.len(), 2);
3557                                 assert_eq!(path.last().unwrap().pubkey, nodes[2]);
3558                                 total_amount_paid_msat += path.last().unwrap().fee_msat;
3559                         }
3560                         assert_eq!(total_amount_paid_msat, 90_000);
3561                 }
3562         }
3563
3564         #[test]
3565         fn min_criteria_consistency() {
3566                 // Test that we don't use an inconsistent metric between updating and walking nodes during
3567                 // our Dijkstra's pass. In the initial version of MPP, the "best source" for a given node
3568                 // was updated with a different criterion from the heap sorting, resulting in loops in
3569                 // calculated paths. We test for that specific case here.
3570
3571                 // We construct a network that looks like this:
3572                 //
3573                 //            node2 -1(3)2- node3
3574                 //              2          2
3575                 //               (2)     (4)
3576                 //                  1   1
3577                 //    node1 -1(5)2- node4 -1(1)2- node6
3578                 //    2
3579                 //   (6)
3580                 //        1
3581                 // our_node
3582                 //
3583                 // We create a loop on the side of our real path - our destination is node 6, with a
3584                 // previous hop of node 4. From 4, the cheapest previous path is channel 2 from node 2,
3585                 // followed by node 3 over channel 3. Thereafter, the cheapest next-hop is back to node 4
3586                 // (this time over channel 4). Channel 4 has 0 htlc_minimum_msat whereas channel 1 (the
3587                 // other channel with a previous-hop of node 4) has a high (but irrelevant to the overall
3588                 // payment) htlc_minimum_msat. In the original algorithm, this resulted in node4's
3589                 // "previous hop" being set to node 3, creating a loop in the path.
3590                 let secp_ctx = Secp256k1::new();
3591                 let logger = Arc::new(test_utils::TestLogger::new());
3592                 let net_graph_msg_handler = NetGraphMsgHandler::new(genesis_block(Network::Testnet).header.block_hash(), None, Arc::clone(&logger));
3593                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3594
3595                 add_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
3596                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3597                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3598                         short_channel_id: 6,
3599                         timestamp: 1,
3600                         flags: 0,
3601                         cltv_expiry_delta: (6 << 8) | 0,
3602                         htlc_minimum_msat: 0,
3603                         htlc_maximum_msat: OptionalField::Absent,
3604                         fee_base_msat: 0,
3605                         fee_proportional_millionths: 0,
3606                         excess_data: Vec::new()
3607                 });
3608                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
3609
3610                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
3611                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3612                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3613                         short_channel_id: 5,
3614                         timestamp: 1,
3615                         flags: 0,
3616                         cltv_expiry_delta: (5 << 8) | 0,
3617                         htlc_minimum_msat: 0,
3618                         htlc_maximum_msat: OptionalField::Absent,
3619                         fee_base_msat: 100,
3620                         fee_proportional_millionths: 0,
3621                         excess_data: Vec::new()
3622                 });
3623                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
3624
3625                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
3626                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3627                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3628                         short_channel_id: 4,
3629                         timestamp: 1,
3630                         flags: 0,
3631                         cltv_expiry_delta: (4 << 8) | 0,
3632                         htlc_minimum_msat: 0,
3633                         htlc_maximum_msat: OptionalField::Absent,
3634                         fee_base_msat: 0,
3635                         fee_proportional_millionths: 0,
3636                         excess_data: Vec::new()
3637                 });
3638                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
3639
3640                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
3641                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
3642                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3643                         short_channel_id: 3,
3644                         timestamp: 1,
3645                         flags: 0,
3646                         cltv_expiry_delta: (3 << 8) | 0,
3647                         htlc_minimum_msat: 0,
3648                         htlc_maximum_msat: OptionalField::Absent,
3649                         fee_base_msat: 0,
3650                         fee_proportional_millionths: 0,
3651                         excess_data: Vec::new()
3652                 });
3653                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
3654
3655                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
3656                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
3657                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3658                         short_channel_id: 2,
3659                         timestamp: 1,
3660                         flags: 0,
3661                         cltv_expiry_delta: (2 << 8) | 0,
3662                         htlc_minimum_msat: 0,
3663                         htlc_maximum_msat: OptionalField::Absent,
3664                         fee_base_msat: 0,
3665                         fee_proportional_millionths: 0,
3666                         excess_data: Vec::new()
3667                 });
3668
3669                 add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], &privkeys[6], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
3670                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
3671                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3672                         short_channel_id: 1,
3673                         timestamp: 1,
3674                         flags: 0,
3675                         cltv_expiry_delta: (1 << 8) | 0,
3676                         htlc_minimum_msat: 100,
3677                         htlc_maximum_msat: OptionalField::Absent,
3678                         fee_base_msat: 0,
3679                         fee_proportional_millionths: 0,
3680                         excess_data: Vec::new()
3681                 });
3682                 add_or_update_node(&net_graph_msg_handler, &secp_ctx, &privkeys[6], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
3683
3684                 {
3685                         // Now ensure the route flows simply over nodes 1 and 4 to 6.
3686                         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();
3687                         assert_eq!(route.paths.len(), 1);
3688                         assert_eq!(route.paths[0].len(), 3);
3689
3690                         assert_eq!(route.paths[0][0].pubkey, nodes[1]);
3691                         assert_eq!(route.paths[0][0].short_channel_id, 6);
3692                         assert_eq!(route.paths[0][0].fee_msat, 100);
3693                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (5 << 8) | 0);
3694                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(1));
3695                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(6));
3696
3697                         assert_eq!(route.paths[0][1].pubkey, nodes[4]);
3698                         assert_eq!(route.paths[0][1].short_channel_id, 5);
3699                         assert_eq!(route.paths[0][1].fee_msat, 0);
3700                         assert_eq!(route.paths[0][1].cltv_expiry_delta, (1 << 8) | 0);
3701                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(4));
3702                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(5));
3703
3704                         assert_eq!(route.paths[0][2].pubkey, nodes[6]);
3705                         assert_eq!(route.paths[0][2].short_channel_id, 1);
3706                         assert_eq!(route.paths[0][2].fee_msat, 10_000);
3707                         assert_eq!(route.paths[0][2].cltv_expiry_delta, 42);
3708                         assert_eq!(route.paths[0][2].node_features.le_flags(), &id_to_feature_flags(6));
3709                         assert_eq!(route.paths[0][2].channel_features.le_flags(), &id_to_feature_flags(1));
3710                 }
3711         }
3712
3713
3714         #[test]
3715         fn exact_fee_liquidity_limit() {
3716                 // Test that if, while walking the graph, we find a hop that has exactly enough liquidity
3717                 // for us, including later hop fees, we take it. In the first version of our MPP algorithm
3718                 // we calculated fees on a higher value, resulting in us ignoring such paths.
3719                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3720                 let (our_privkey, our_id, _, nodes) = get_nodes(&secp_ctx);
3721
3722                 // We modify the graph to set the htlc_maximum of channel 2 to below the value we wish to
3723                 // send.
3724                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3725                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3726                         short_channel_id: 2,
3727                         timestamp: 2,
3728                         flags: 0,
3729                         cltv_expiry_delta: 0,
3730                         htlc_minimum_msat: 0,
3731                         htlc_maximum_msat: OptionalField::Present(85_000),
3732                         fee_base_msat: 0,
3733                         fee_proportional_millionths: 0,
3734                         excess_data: Vec::new()
3735                 });
3736
3737                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3738                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3739                         short_channel_id: 12,
3740                         timestamp: 2,
3741                         flags: 0,
3742                         cltv_expiry_delta: (4 << 8) | 1,
3743                         htlc_minimum_msat: 0,
3744                         htlc_maximum_msat: OptionalField::Present(270_000),
3745                         fee_base_msat: 0,
3746                         fee_proportional_millionths: 1000000,
3747                         excess_data: Vec::new()
3748                 });
3749
3750                 {
3751                         // Now, attempt to route 90 sats, which is exactly 90 sats at the last hop, plus the
3752                         // 200% fee charged channel 13 in the 1-to-2 direction.
3753                         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();
3754                         assert_eq!(route.paths.len(), 1);
3755                         assert_eq!(route.paths[0].len(), 2);
3756
3757                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
3758                         assert_eq!(route.paths[0][0].short_channel_id, 12);
3759                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
3760                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
3761                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
3762                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
3763
3764                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
3765                         assert_eq!(route.paths[0][1].short_channel_id, 13);
3766                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
3767                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
3768                         assert_eq!(route.paths[0][1].node_features.le_flags(), &id_to_feature_flags(3));
3769                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
3770                 }
3771         }
3772
3773         #[test]
3774         fn htlc_max_reduction_below_min() {
3775                 // Test that if, while walking the graph, we reduce the value being sent to meet an
3776                 // htlc_maximum_msat, we don't end up undershooting a later htlc_minimum_msat. In the
3777                 // initial version of MPP we'd accept such routes but reject them while recalculating fees,
3778                 // resulting in us thinking there is no possible path, even if other paths exist.
3779                 let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
3780                 let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
3781
3782                 // We modify the graph to set the htlc_minimum of channel 2 and 4 as needed - channel 2
3783                 // gets an htlc_maximum_msat of 80_000 and channel 4 an htlc_minimum_msat of 90_000. We
3784                 // then try to send 90_000.
3785                 update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
3786                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3787                         short_channel_id: 2,
3788                         timestamp: 2,
3789                         flags: 0,
3790                         cltv_expiry_delta: 0,
3791                         htlc_minimum_msat: 0,
3792                         htlc_maximum_msat: OptionalField::Present(80_000),
3793                         fee_base_msat: 0,
3794                         fee_proportional_millionths: 0,
3795                         excess_data: Vec::new()
3796                 });
3797                 update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
3798                         chain_hash: genesis_block(Network::Testnet).header.block_hash(),
3799                         short_channel_id: 4,
3800                         timestamp: 2,
3801                         flags: 0,
3802                         cltv_expiry_delta: (4 << 8) | 1,
3803                         htlc_minimum_msat: 90_000,
3804                         htlc_maximum_msat: OptionalField::Absent,
3805                         fee_base_msat: 0,
3806                         fee_proportional_millionths: 0,
3807                         excess_data: Vec::new()
3808                 });
3809
3810                 {
3811                         // Now, attempt to route 90 sats, hitting the htlc_minimum on channel 4, but
3812                         // overshooting the htlc_maximum on channel 2. Thus, we should pick the (absurdly
3813                         // expensive) channels 12-13 path.
3814                         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();
3815                         assert_eq!(route.paths.len(), 1);
3816                         assert_eq!(route.paths[0].len(), 2);
3817
3818                         assert_eq!(route.paths[0][0].pubkey, nodes[7]);
3819                         assert_eq!(route.paths[0][0].short_channel_id, 12);
3820                         assert_eq!(route.paths[0][0].fee_msat, 90_000*2);
3821                         assert_eq!(route.paths[0][0].cltv_expiry_delta, (13 << 8) | 1);
3822                         assert_eq!(route.paths[0][0].node_features.le_flags(), &id_to_feature_flags(8));
3823                         assert_eq!(route.paths[0][0].channel_features.le_flags(), &id_to_feature_flags(12));
3824
3825                         assert_eq!(route.paths[0][1].pubkey, nodes[2]);
3826                         assert_eq!(route.paths[0][1].short_channel_id, 13);
3827                         assert_eq!(route.paths[0][1].fee_msat, 90_000);
3828                         assert_eq!(route.paths[0][1].cltv_expiry_delta, 42);
3829                         assert_eq!(route.paths[0][1].node_features.le_flags(), InvoiceFeatures::known().le_flags());
3830                         assert_eq!(route.paths[0][1].channel_features.le_flags(), &id_to_feature_flags(13));
3831                 }
3832         }
3833
3834         use std::fs::File;
3835         use util::ser::Readable;
3836         /// Tries to open a network graph file, or panics with a URL to fetch it.
3837         pub(super) fn get_route_file() -> Result<std::fs::File, std::io::Error> {
3838                 let res = File::open("net_graph-2021-02-12.bin") // By default we're run in RL/lightning
3839                         .or_else(|_| File::open("lightning/net_graph-2021-02-12.bin")) // We may be run manually in RL/
3840                         .or_else(|_| { // Fall back to guessing based on the binary location
3841                                 // path is likely something like .../rust-lightning/target/debug/deps/lightning-...
3842                                 let mut path = std::env::current_exe().unwrap();
3843                                 path.pop(); // lightning-...
3844                                 path.pop(); // deps
3845                                 path.pop(); // debug
3846                                 path.pop(); // target
3847                                 path.push("lightning");
3848                                 path.push("net_graph-2021-02-12.bin");
3849                                 eprintln!("{}", path.to_str().unwrap());
3850                                 File::open(path)
3851                         });
3852                 #[cfg(require_route_graph_test)]
3853                 return Ok(res.expect("Didn't have route graph and was configured to require it"));
3854                 res
3855         }
3856
3857         pub(super) fn random_init_seed() -> u64 {
3858                 // Because the default HashMap in std pulls OS randomness, we can use it as a (bad) RNG.
3859                 use std::hash::{BuildHasher, Hasher};
3860                 let seed = std::collections::hash_map::RandomState::new().build_hasher().finish();
3861                 println!("Using seed of {}", seed);
3862                 seed
3863         }
3864
3865         #[test]
3866         fn generate_routes() {
3867                 let mut d = match get_route_file() {
3868                         Ok(f) => f,
3869                         Err(_) => {
3870                                 eprintln!("Please fetch https://bitcoin.ninja/ldk-net_graph-879e309c128-2020-02-12.bin and place it at lightning/net_graph-2021-02-12.bin");
3871                                 return;
3872                         },
3873                 };
3874                 let graph = NetworkGraph::read(&mut d).unwrap();
3875
3876                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3877                 let mut seed = random_init_seed() as usize;
3878                 'load_endpoints: for _ in 0..10 {
3879                         loop {
3880                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3881                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3882                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3883                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3884                                 let amt = seed as u64 % 200_000_000;
3885                                 if get_route(src, &graph, dst, None, None, &[], amt, 42, &test_utils::TestLogger::new()).is_ok() {
3886                                         continue 'load_endpoints;
3887                                 }
3888                         }
3889                 }
3890         }
3891
3892         #[test]
3893         fn generate_routes_mpp() {
3894                 let mut d = match get_route_file() {
3895                         Ok(f) => f,
3896                         Err(_) => {
3897                                 eprintln!("Please fetch https://bitcoin.ninja/ldk-net_graph-879e309c128-2020-02-12.bin and place it at lightning/net_graph-2021-02-12.bin");
3898                                 return;
3899                         },
3900                 };
3901                 let graph = NetworkGraph::read(&mut d).unwrap();
3902
3903                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3904                 let mut seed = random_init_seed() as usize;
3905                 'load_endpoints: for _ in 0..10 {
3906                         loop {
3907                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3908                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3909                                 seed = seed.overflowing_mul(0xdeadbeef).0;
3910                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3911                                 let amt = seed as u64 % 200_000_000;
3912                                 if get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &test_utils::TestLogger::new()).is_ok() {
3913                                         continue 'load_endpoints;
3914                                 }
3915                         }
3916                 }
3917         }
3918 }
3919
3920 #[cfg(all(test, feature = "unstable"))]
3921 mod benches {
3922         use super::*;
3923         use util::logger::{Logger, Record};
3924
3925         use std::fs::File;
3926         use test::Bencher;
3927
3928         struct DummyLogger {}
3929         impl Logger for DummyLogger {
3930                 fn log(&self, _record: &Record) {}
3931         }
3932
3933         #[bench]
3934         fn generate_routes(bench: &mut Bencher) {
3935                 let mut d = tests::get_route_file()
3936                         .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");
3937                 let graph = NetworkGraph::read(&mut d).unwrap();
3938
3939                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3940                 let mut path_endpoints = Vec::new();
3941                 let mut seed: usize = 0xdeadbeef;
3942                 'load_endpoints: for _ in 0..100 {
3943                         loop {
3944                                 seed *= 0xdeadbeef;
3945                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3946                                 seed *= 0xdeadbeef;
3947                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3948                                 let amt = seed as u64 % 1_000_000;
3949                                 if get_route(src, &graph, dst, None, None, &[], amt, 42, &DummyLogger{}).is_ok() {
3950                                         path_endpoints.push((src, dst, amt));
3951                                         continue 'load_endpoints;
3952                                 }
3953                         }
3954                 }
3955
3956                 // ...then benchmark finding paths between the nodes we learned.
3957                 let mut idx = 0;
3958                 bench.iter(|| {
3959                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
3960                         assert!(get_route(src, &graph, dst, None, None, &[], amt, 42, &DummyLogger{}).is_ok());
3961                         idx += 1;
3962                 });
3963         }
3964
3965         #[bench]
3966         fn generate_mpp_routes(bench: &mut Bencher) {
3967                 let mut d = tests::get_route_file()
3968                         .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");
3969                 let graph = NetworkGraph::read(&mut d).unwrap();
3970
3971                 // First, get 100 (source, destination) pairs for which route-getting actually succeeds...
3972                 let mut path_endpoints = Vec::new();
3973                 let mut seed: usize = 0xdeadbeef;
3974                 'load_endpoints: for _ in 0..100 {
3975                         loop {
3976                                 seed *= 0xdeadbeef;
3977                                 let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3978                                 seed *= 0xdeadbeef;
3979                                 let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
3980                                 let amt = seed as u64 % 1_000_000;
3981                                 if get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &DummyLogger{}).is_ok() {
3982                                         path_endpoints.push((src, dst, amt));
3983                                         continue 'load_endpoints;
3984                                 }
3985                         }
3986                 }
3987
3988                 // ...then benchmark finding paths between the nodes we learned.
3989                 let mut idx = 0;
3990                 bench.iter(|| {
3991                         let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
3992                         assert!(get_route(src, &graph, dst, Some(InvoiceFeatures::known()), None, &[], amt, 42, &DummyLogger{}).is_ok());
3993                         idx += 1;
3994                 });
3995         }
3996 }